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Overview
Comment:Restructure the OS interface yet again. This time make the OsFile object a virtual base class which is subclassed for unix, windows, and the crash test simulator. Add the new file "os.c" for common os layer code. Move all OS-specific routines into the sqlite3Os structure. (CVS 2795)
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1:bd8740d1aecba69e1b5d64d43db07e8ad8841f07
User & Date: drh 2005-11-30 03:20:31
Context
2005-12-02
01:57
Documentation updates. (CVS 2796) check-in: 2ffb90c3 user: drh tags: trunk
2005-11-30
03:20
Restructure the OS interface yet again. This time make the OsFile object a virtual base class which is subclassed for unix, windows, and the crash test simulator. Add the new file "os.c" for common os layer code. Move all OS-specific routines into the sqlite3Os structure. (CVS 2795) check-in: bd8740d1 user: drh tags: trunk
2005-11-29
19:56
The crash test works now, at least on unix. Untested on windows. But it never worked on windows before so if it still does not there is no big loss. I am still troubled by the current design of the OS overloading mechanism. Expect to see more changes. (CVS 2794) check-in: fa1d7ecf user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to Makefile.in.

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TCC += -DSQLITE_OMIT_CURSOR

# Object files for the SQLite library.
#
LIBOBJ = alter.lo analyze.lo attach.lo auth.lo btree.lo build.lo \
         callback.lo complete.lo date.lo \
         delete.lo expr.lo func.lo hash.lo insert.lo \
         main.lo opcodes.lo os_unix.lo os_win.lo \
         pager.lo parse.lo pragma.lo prepare.lo printf.lo random.lo \
         select.lo table.lo tokenize.lo trigger.lo update.lo \
         util.lo vacuum.lo \
         vdbe.lo vdbeapi.lo vdbeaux.lo vdbefifo.lo vdbemem.lo \
         where.lo utf.lo legacy.lo

# All of the source code files.
................................................................................
  $(TOP)/src/expr.c \
  $(TOP)/src/func.c \
  $(TOP)/src/hash.c \
  $(TOP)/src/hash.h \
  $(TOP)/src/insert.c \
  $(TOP)/src/legacy.c \
  $(TOP)/src/main.c \

  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pager.h \
  $(TOP)/src/parse.y \
  $(TOP)/src/pragma.c \
  $(TOP)/src/prepare.c \
................................................................................

opcodes.c:	opcodes.h $(TOP)/mkopcodec.awk
	sort -n -b +2 opcodes.h | awk -f $(TOP)/mkopcodec.awk >opcodes.c

opcodes.h:	parse.h $(TOP)/src/vdbe.c $(TOP)/mkopcodeh.awk
	cat parse.h $(TOP)/src/vdbe.c | awk -f $(TOP)/mkopcodeh.awk >opcodes.h




os_unix.lo:	$(TOP)/src/os_unix.c $(HDR)
	$(LTCOMPILE) -c $(TOP)/src/os_unix.c

os_win.lo:	$(TOP)/src/os_win.c $(HDR)
	$(LTCOMPILE) -c $(TOP)/src/os_win.c

parse.lo:	parse.c $(HDR)







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TCC += -DSQLITE_OMIT_CURSOR

# Object files for the SQLite library.
#
LIBOBJ = alter.lo analyze.lo attach.lo auth.lo btree.lo build.lo \
         callback.lo complete.lo date.lo \
         delete.lo expr.lo func.lo hash.lo insert.lo \
         main.lo opcodes.lo os.lo os_unix.lo os_win.lo \
         pager.lo parse.lo pragma.lo prepare.lo printf.lo random.lo \
         select.lo table.lo tokenize.lo trigger.lo update.lo \
         util.lo vacuum.lo \
         vdbe.lo vdbeapi.lo vdbeaux.lo vdbefifo.lo vdbemem.lo \
         where.lo utf.lo legacy.lo

# All of the source code files.
................................................................................
  $(TOP)/src/expr.c \
  $(TOP)/src/func.c \
  $(TOP)/src/hash.c \
  $(TOP)/src/hash.h \
  $(TOP)/src/insert.c \
  $(TOP)/src/legacy.c \
  $(TOP)/src/main.c \
  $(TOP)/src/os.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pager.h \
  $(TOP)/src/parse.y \
  $(TOP)/src/pragma.c \
  $(TOP)/src/prepare.c \
................................................................................

opcodes.c:	opcodes.h $(TOP)/mkopcodec.awk
	sort -n -b +2 opcodes.h | awk -f $(TOP)/mkopcodec.awk >opcodes.c

opcodes.h:	parse.h $(TOP)/src/vdbe.c $(TOP)/mkopcodeh.awk
	cat parse.h $(TOP)/src/vdbe.c | awk -f $(TOP)/mkopcodeh.awk >opcodes.h

os.lo:	$(TOP)/src/os.c $(HDR)
	$(LTCOMPILE) -c $(TOP)/src/os.c

os_unix.lo:	$(TOP)/src/os_unix.c $(HDR)
	$(LTCOMPILE) -c $(TOP)/src/os_unix.c

os_win.lo:	$(TOP)/src/os_win.c $(HDR)
	$(LTCOMPILE) -c $(TOP)/src/os_win.c

parse.lo:	parse.c $(HDR)

Changes to main.mk.

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TCCX = $(TCC) $(OPTS) $(THREADSAFE) $(USLEEP) -I. -I$(TOP)/src

# Object files for the SQLite library.
#
LIBOBJ+= alter.o analyze.o attach.o auth.o btree.o build.o \
         callback.o complete.o date.o delete.o \
         expr.o func.o hash.o insert.o \
         main.o opcodes.o os_unix.o os_win.o \
         pager.o parse.o pragma.o prepare.o printf.o random.o \
         select.o table.o tclsqlite.o tokenize.o trigger.o \
         update.o util.o vacuum.o \
         vdbe.o vdbeapi.o vdbeaux.o vdbefifo.o vdbemem.o \
         where.o utf.o legacy.o

# All of the source code files.
................................................................................
  $(TOP)/src/expr.c \
  $(TOP)/src/func.c \
  $(TOP)/src/hash.c \
  $(TOP)/src/hash.h \
  $(TOP)/src/insert.c \
  $(TOP)/src/legacy.c \
  $(TOP)/src/main.c \

  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pager.h \
  $(TOP)/src/parse.y \
  $(TOP)/src/pragma.c \
  $(TOP)/src/prepare.c \
................................................................................
	$(TCCX) -c opcodes.c

opcodes.c:	opcodes.h $(TOP)/mkopcodec.awk
	sort -n -b +2 opcodes.h | awk -f $(TOP)/mkopcodec.awk >opcodes.c

opcodes.h:	parse.h $(TOP)/src/vdbe.c $(TOP)/mkopcodeh.awk
	cat parse.h $(TOP)/src/vdbe.c | awk -f $(TOP)/mkopcodeh.awk >opcodes.h




os_unix.o:	$(TOP)/src/os_unix.c $(HDR)
	$(TCCX) -c $(TOP)/src/os_unix.c

os_win.o:	$(TOP)/src/os_win.c $(HDR)
	$(TCCX) -c $(TOP)/src/os_win.c








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TCCX = $(TCC) $(OPTS) $(THREADSAFE) $(USLEEP) -I. -I$(TOP)/src

# Object files for the SQLite library.
#
LIBOBJ+= alter.o analyze.o attach.o auth.o btree.o build.o \
         callback.o complete.o date.o delete.o \
         expr.o func.o hash.o insert.o \
         main.o opcodes.o os.o os_unix.o os_win.o \
         pager.o parse.o pragma.o prepare.o printf.o random.o \
         select.o table.o tclsqlite.o tokenize.o trigger.o \
         update.o util.o vacuum.o \
         vdbe.o vdbeapi.o vdbeaux.o vdbefifo.o vdbemem.o \
         where.o utf.o legacy.o

# All of the source code files.
................................................................................
  $(TOP)/src/expr.c \
  $(TOP)/src/func.c \
  $(TOP)/src/hash.c \
  $(TOP)/src/hash.h \
  $(TOP)/src/insert.c \
  $(TOP)/src/legacy.c \
  $(TOP)/src/main.c \
  $(TOP)/src/os.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pager.h \
  $(TOP)/src/parse.y \
  $(TOP)/src/pragma.c \
  $(TOP)/src/prepare.c \
................................................................................
	$(TCCX) -c opcodes.c

opcodes.c:	opcodes.h $(TOP)/mkopcodec.awk
	sort -n -b +2 opcodes.h | awk -f $(TOP)/mkopcodec.awk >opcodes.c

opcodes.h:	parse.h $(TOP)/src/vdbe.c $(TOP)/mkopcodeh.awk
	cat parse.h $(TOP)/src/vdbe.c | awk -f $(TOP)/mkopcodeh.awk >opcodes.h

os.o:	$(TOP)/src/os.c $(HDR)
	$(TCCX) -c $(TOP)/src/os.c

os_unix.o:	$(TOP)/src/os_unix.c $(HDR)
	$(TCCX) -c $(TOP)/src/os_unix.c

os_win.o:	$(TOP)/src/os_win.c $(HDR)
	$(TCCX) -c $(TOP)/src/os_win.c

Changes to src/date.c.

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** This file contains the C functions that implement date and time
** functions for SQLite.  
**
** There is only one exported symbol in this file - the function
** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: date.c,v 1.45 2005/06/25 18:42:14 drh Exp $
**
** NOTES:
**
** SQLite processes all times and dates as Julian Day numbers.  The
** dates and times are stored as the number of days since noon
** in Greenwich on November 24, 4714 B.C. according to the Gregorian
** calendar system.
................................................................................
  memset(p, 0, sizeof(*p));
  if( parseYyyyMmDd(zDate,p)==0 ){
    return 0;
  }else if( parseHhMmSs(zDate, p)==0 ){
    return 0;
  }else if( sqlite3StrICmp(zDate,"now")==0){
    double r;
    sqlite3OsCurrentTime(&r);
    p->rJD = r;
    p->validJD = 1;
    return 0;
  }else if( sqlite3IsNumber(zDate, 0, SQLITE_UTF8) ){
    getValue(zDate, &p->rJD);
    p->validJD = 1;
    return 0;
................................................................................
    int s = x.s + 0.5;
    x.s = s;
  }
  x.tz = 0;
  x.validJD = 0;
  computeJD(&x);
  t = (x.rJD-2440587.5)*86400.0 + 0.5;
  sqlite3OsEnterMutex();
  pTm = localtime(&t);
  y.Y = pTm->tm_year + 1900;
  y.M = pTm->tm_mon + 1;
  y.D = pTm->tm_mday;
  y.h = pTm->tm_hour;
  y.m = pTm->tm_min;
  y.s = pTm->tm_sec;
  sqlite3OsLeaveMutex();
  y.validYMD = 1;
  y.validHMS = 1;
  y.validJD = 0;
  y.validTZ = 0;
  computeJD(&y);
  return y.rJD - x.rJD;
}
................................................................................
    extern int sqlite3_current_time;  /* See os_XXX.c */
    if( sqlite3_current_time ){
      t = sqlite3_current_time;
    }
  }
#endif

  sqlite3OsEnterMutex();
  strftime(zBuf, 20, zFormat, gmtime(&t));
  sqlite3OsLeaveMutex();

  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
}
#endif

/*
** This function registered all of the above C functions as SQL







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** This file contains the C functions that implement date and time
** functions for SQLite.  
**
** There is only one exported symbol in this file - the function
** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: date.c,v 1.46 2005/11/30 03:20:31 drh Exp $
**
** NOTES:
**
** SQLite processes all times and dates as Julian Day numbers.  The
** dates and times are stored as the number of days since noon
** in Greenwich on November 24, 4714 B.C. according to the Gregorian
** calendar system.
................................................................................
  memset(p, 0, sizeof(*p));
  if( parseYyyyMmDd(zDate,p)==0 ){
    return 0;
  }else if( parseHhMmSs(zDate, p)==0 ){
    return 0;
  }else if( sqlite3StrICmp(zDate,"now")==0){
    double r;
    sqlite3Os.xCurrentTime(&r);
    p->rJD = r;
    p->validJD = 1;
    return 0;
  }else if( sqlite3IsNumber(zDate, 0, SQLITE_UTF8) ){
    getValue(zDate, &p->rJD);
    p->validJD = 1;
    return 0;
................................................................................
    int s = x.s + 0.5;
    x.s = s;
  }
  x.tz = 0;
  x.validJD = 0;
  computeJD(&x);
  t = (x.rJD-2440587.5)*86400.0 + 0.5;
  sqlite3Os.xEnterMutex();
  pTm = localtime(&t);
  y.Y = pTm->tm_year + 1900;
  y.M = pTm->tm_mon + 1;
  y.D = pTm->tm_mday;
  y.h = pTm->tm_hour;
  y.m = pTm->tm_min;
  y.s = pTm->tm_sec;
  sqlite3Os.xLeaveMutex();
  y.validYMD = 1;
  y.validHMS = 1;
  y.validJD = 0;
  y.validTZ = 0;
  computeJD(&y);
  return y.rJD - x.rJD;
}
................................................................................
    extern int sqlite3_current_time;  /* See os_XXX.c */
    if( sqlite3_current_time ){
      t = sqlite3_current_time;
    }
  }
#endif

  sqlite3Os.xEnterMutex();
  strftime(zBuf, 20, zFormat, gmtime(&t));
  sqlite3Os.xLeaveMutex();

  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
}
#endif

/*
** This function registered all of the above C functions as SQL

Changes to src/main.c.

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**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.303 2005/10/20 07:28:18 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** The following constant value is used by the SQLITE_BIGENDIAN and
................................................................................
  if( db->pErr ){
    sqlite3ValueFree(db->pErr);
  }

#ifndef SQLITE_OMIT_GLOBALRECOVER
  {
    sqlite3 *pPrev;
    sqlite3OsEnterMutex();
    pPrev = pDbList;
    while( pPrev && pPrev->pNext!=db ){
      pPrev = pPrev->pNext;
    }
    if( pPrev ){
      pPrev->pNext = db->pNext;
    }else{
      assert( pDbList==db );
      pDbList = db->pNext;
    }
    sqlite3OsLeaveMutex();
  }
#endif

  db->magic = SQLITE_MAGIC_ERROR;
  sqliteFree(db);
  return SQLITE_OK;
}
................................................................................
    delay = delays[NDELAY-1];
    prior = totals[NDELAY-1] + delay*(count-(NDELAY-1));
  }
  if( prior + delay > timeout ){
    delay = timeout - prior;
    if( delay<=0 ) return 0;
  }
  sqlite3OsSleep(delay);
  return 1;
#else
  int timeout = ((sqlite3 *)ptr)->busyTimeout;
  if( (count+1)*1000 > timeout ){
    return 0;
  }
  sqlite3OsSleep(1000);
  return 1;
#endif
}

/*
** Invoke the given busy handler.
**
................................................................................
opendb_out:
  if( sqlite3_errcode(db)==SQLITE_OK && sqlite3_malloc_failed ){
    sqlite3Error(db, SQLITE_NOMEM, 0);
  }
  *ppDb = db;
#ifndef SQLITE_OMIT_GLOBALRECOVER
  if( db ){
    sqlite3OsEnterMutex();
    db->pNext = pDbList;
    pDbList = db;
    sqlite3OsLeaveMutex();
  }
#endif
  return sqlite3_errcode(db);
}

/*
** Open a new database handle.







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**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.304 2005/11/30 03:20:31 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** The following constant value is used by the SQLITE_BIGENDIAN and
................................................................................
  if( db->pErr ){
    sqlite3ValueFree(db->pErr);
  }

#ifndef SQLITE_OMIT_GLOBALRECOVER
  {
    sqlite3 *pPrev;
    sqlite3Os.xEnterMutex();
    pPrev = pDbList;
    while( pPrev && pPrev->pNext!=db ){
      pPrev = pPrev->pNext;
    }
    if( pPrev ){
      pPrev->pNext = db->pNext;
    }else{
      assert( pDbList==db );
      pDbList = db->pNext;
    }
    sqlite3Os.xLeaveMutex();
  }
#endif

  db->magic = SQLITE_MAGIC_ERROR;
  sqliteFree(db);
  return SQLITE_OK;
}
................................................................................
    delay = delays[NDELAY-1];
    prior = totals[NDELAY-1] + delay*(count-(NDELAY-1));
  }
  if( prior + delay > timeout ){
    delay = timeout - prior;
    if( delay<=0 ) return 0;
  }
  sqlite3Os.xSleep(delay);
  return 1;
#else
  int timeout = ((sqlite3 *)ptr)->busyTimeout;
  if( (count+1)*1000 > timeout ){
    return 0;
  }
  sqlite3Os.xSleep(1000);
  return 1;
#endif
}

/*
** Invoke the given busy handler.
**
................................................................................
opendb_out:
  if( sqlite3_errcode(db)==SQLITE_OK && sqlite3_malloc_failed ){
    sqlite3Error(db, SQLITE_NOMEM, 0);
  }
  *ppDb = db;
#ifndef SQLITE_OMIT_GLOBALRECOVER
  if( db ){
    sqlite3Os.xEnterMutex();
    db->pNext = pDbList;
    pDbList = db;
    sqlite3Os.xLeaveMutex();
  }
#endif
  return sqlite3_errcode(db);
}

/*
** Open a new database handle.

Added src/os.c.















































































































































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/*
** 2005 November 29
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains OS interface code that is common to all
** architectures.
*/
#include "sqliteInt.h"
#include "os.h"

/*
** The following routines are convenience wrappers around methods
** of the OsFile object.  This is mostly just syntactic sugar.  All
** of this would be completely automatic if SQLite were coded using
** C++ instead of plain old C.
*/
int sqlite3OsClose(OsFile **pId){
  OsFile *id;
  if( pId!=0 && (id = *pId)!=0 ){
    return id->pMethod->xClose(pId);
  }else{
    return SQLITE_OK;
  }
}
int sqlite3OsOpenDirectory(OsFile *id, const char *zName){
  return id->pMethod->xOpenDirectory(id, zName);
}
int sqlite3OsRead(OsFile *id, void *pBuf, int amt){
  return id->pMethod->xRead(id, pBuf, amt);
}
int sqlite3OsWrite(OsFile *id, const void *pBuf, int amt){
  return id->pMethod->xWrite(id, pBuf, amt);
}
int sqlite3OsSeek(OsFile *id, i64 offset){
  return id->pMethod->xSeek(id, offset);
}
int sqlite3OsTruncate(OsFile *id, i64 size){
  return id->pMethod->xTruncate(id, size);
}
int sqlite3OsSync(OsFile *id, int fullsync){
  return id->pMethod->xSync(id, fullsync);
}
void sqlite3OsSetFullSync(OsFile *id, int value){
  id->pMethod->xSetFullSync(id, value);
}
int sqlite3OsFileHandle(OsFile *id){
  return id->pMethod->xFileHandle(id);
}
int sqlite3OsFileSize(OsFile *id, i64 *pSize){
  return id->pMethod->xFileSize(id, pSize);
}
int sqlite3OsLock(OsFile *id, int lockType){
  return id->pMethod->xLock(id, lockType);
}
int sqlite3OsUnlock(OsFile *id, int lockType){
  return id->pMethod->xUnlock(id, lockType);
}
int sqlite3OsLockState(OsFile *id){
  return id->pMethod->xLockState(id);
}
int sqlite3OsCheckReservedLock(OsFile *id){
  return id->pMethod->xCheckReservedLock(id);
}

Changes to src/os.h.

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#  define OS_UNIX 0
# endif
#else
# ifndef OS_WIN
#  define OS_WIN 0
# endif
#endif


/*



























** The OsFile object describes an open disk file in an OS-dependent way.



*/
typedef struct OsFile OsFile;



/*
** Define the maximum size of a temporary filename
*/
#if OS_WIN
# include <windows.h>
# define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
................................................................................

#define RESERVED_BYTE     (PENDING_BYTE+1)
#define SHARED_FIRST      (PENDING_BYTE+2)
#define SHARED_SIZE       510

/*
** A single global instance of the following structure holds pointers to the
** various disk I/O routines.
*/
extern struct sqlite3IoVtbl {
  int (*xDelete)(const char*);
  int (*xFileExists)(const char*);
  int (*xOpenReadWrite)(const char*, OsFile**, int*);
  int (*xOpenExclusive)(const char*, OsFile**, int);
  int (*xOpenReadOnly)(const char*, OsFile**);
  int (*xOpenDirectory)(const char*, OsFile*);
  int (*xSyncDirectory)(const char*);
  int (*xTempFileName)(char*);
  int (*xIsDirWritable)(char*);
  int (*xClose)(OsFile**);
  int (*xRead)(OsFile*, void*, int amt);
  int (*xWrite)(OsFile*, const void*, int amt);
  int (*xSeek)(OsFile*, i64 offset);
  int (*xSync)(OsFile*, int);
  int (*xTruncate)(OsFile*, i64 size);
  int (*xFileSize)(OsFile*, i64 *pSize);
  char *(*xFullPathname)(const char*);
  int (*xLock)(OsFile*, int);
  int (*xUnlock)(OsFile*, int);
  int (*xCheckReservedLock)(OsFile *id);
  void (*xSetFullSync)(OsFile *id, int setting);
  int (*xFileHandle)(OsFile *id);
  int (*xLockState)(OsFile *id);
} sqlite3Io;

/* The interface for file I/O is above.  Other miscellaneous functions
** are below */

int sqlite3OsRandomSeed(char*);
int sqlite3OsSleep(int ms);
int sqlite3OsCurrentTime(double*);
void sqlite3OsEnterMutex(void);
void sqlite3OsLeaveMutex(void);


#endif /* _SQLITE_OS_H_ */












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#  define OS_UNIX 0
# endif
#else
# ifndef OS_WIN
#  define OS_WIN 0
# endif
#endif


/*
** Forward declarations
*/
typedef struct OsFile OsFile;
typedef struct IoMethod IoMethod;

/*
** An instance of the following structure contains pointers to all
** methods on an OsFile object.
*/
struct IoMethod {
  int (*xClose)(OsFile**);
  int (*xOpenDirectory)(OsFile*, const char*);
  int (*xRead)(OsFile*, void*, int amt);
  int (*xWrite)(OsFile*, const void*, int amt);
  int (*xSeek)(OsFile*, i64 offset);
  int (*xTruncate)(OsFile*, i64 size);
  int (*xSync)(OsFile*, int);
  void (*xSetFullSync)(OsFile *id, int setting);
  int (*xFileHandle)(OsFile *id);
  int (*xFileSize)(OsFile*, i64 *pSize);
  int (*xLock)(OsFile*, int);
  int (*xUnlock)(OsFile*, int);
  int (*xLockState)(OsFile *id);
  int (*xCheckReservedLock)(OsFile *id);
};

/*
** The OsFile object describes an open disk file in an OS-dependent way.
** The version of OsFile defined here is a generic versions.  Each Os
** implementation defines its own subclass of this structure that contains
** additional information needed to handle file I/O.
*/
struct OsFile {
  IoMethod const *pMethod;
};

/*
** Define the maximum size of a temporary filename
*/
#if OS_WIN
# include <windows.h>
# define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
................................................................................

#define RESERVED_BYTE     (PENDING_BYTE+1)
#define SHARED_FIRST      (PENDING_BYTE+2)
#define SHARED_SIZE       510

/*
** A single global instance of the following structure holds pointers to the
** various system-specific interface routines.
*/
extern struct sqlite3OsVtbl {


  int (*xOpenReadWrite)(const char*, OsFile**, int*);
  int (*xOpenExclusive)(const char*, OsFile**, int);
  int (*xOpenReadOnly)(const char*, OsFile**);

  int (*xDelete)(const char*);
  int (*xFileExists)(const char*);
  char *(*xFullPathname)(const char*);
  int (*xIsDirWritable)(char*);
  int (*xSyncDirectory)(const char*);
  int (*xTempFileName)(char*);

  int  (*xRandomSeed)(char*);
  int  (*xSleep)(int ms);
  int  (*xCurrentTime)(double*);
  void (*xEnterMutex)(void);
  void (*xLeaveMutex)(void);
} sqlite3Os;

/*
** Prototypes for routines found in os.c
*/
int sqlite3OsClose(OsFile**);
int sqlite3OsOpenDirectory(OsFile*, const char*);
int sqlite3OsRead(OsFile*, void*, int amt);
int sqlite3OsWrite(OsFile*, const void*, int amt);
int sqlite3OsSeek(OsFile*, i64 offset);
int sqlite3OsTruncate(OsFile*, i64 size);
int sqlite3OsSync(OsFile*, int);
void sqlite3OsSetFullSync(OsFile *id, int setting);
int sqlite3OsFileHandle(OsFile *id);
int sqlite3OsFileSize(OsFile*, i64 *pSize);
int sqlite3OsLock(OsFile*, int);
int sqlite3OsUnlock(OsFile*, int);
int sqlite3OsLockState(OsFile *id);
int sqlite3OsCheckReservedLock(OsFile *id);


#endif /* _SQLITE_OS_H_ */

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1631
#ifndef SQLITE_DEFAULT_FILE_PERMISSIONS
# define SQLITE_DEFAULT_FILE_PERMISSIONS 0644
#endif



/*
** The OsFile structure is a operating-system dependent representation
** of an open file handle.  It is defined differently for each architecture.
**
** This is the definition for Unix.
**
** OsFile.locktype takes one of the values SHARED_LOCK, RESERVED_LOCK,
** PENDING_LOCK or EXCLUSIVE_LOCK.
*/

struct OsFile {

  struct openCnt *pOpen;    /* Info about all open fd's on this inode */
  struct lockInfo *pLock;   /* Info about locks on this inode */
  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
  unsigned char isOpen;     /* True if needs to be closed */
  unsigned char fullSync;   /* Use F_FULLSYNC if available */
  int dirfd;                /* File descriptor for the directory */
................................................................................
/*
** Return TRUE if the named file exists.
*/
static int unixFileExists(const char *zFilename){
  return access(zFilename, 0)==0;
}

/*
** Allocate memory for an OsFile.  Initialize the new OsFile
** to the value given in pInit and return a pointer to the new
** OsFile.  If we run out of memory, close the file and return NULL.
*/
static OsFile *allocateOsFile(OsFile *pInit){
  OsFile *pNew;
  pNew = sqliteMalloc( sizeof(OsFile) );
  if( pNew==0 ){
    close(pInit->h);
  }else{
    *pNew = *pInit;
  }
  return pNew;
}

/*
** Attempt to open a file for both reading and writing.  If that
** fails, try opening it read-only.  If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id
................................................................................
*/
static int unixOpenReadWrite(
  const char *zFilename,
  OsFile **pId,
  int *pReadonly
){
  int rc;
  OsFile f;

  assert( 0==*pId );
  f.dirfd = -1;
  SET_THREADID(&f);
  f.h = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE|O_BINARY,
                          SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( f.h<0 ){
................................................................................
    if( f.h<0 ){
      return SQLITE_CANTOPEN; 
    }
    *pReadonly = 1;
  }else{
    *pReadonly = 0;
  }
  sqlite3OsEnterMutex();
  rc = findLockInfo(f.h, &f.pLock, &f.pOpen);
  sqlite3OsLeaveMutex();
  if( rc ){
    close(f.h);
    return SQLITE_NOMEM;
  }
  f.locktype = 0;
  TRACE3("OPEN    %-3d %s\n", f.h, zFilename);
  *pId = allocateOsFile(&f);
  if( *pId==0 ){
    return SQLITE_NOMEM;
  }else{
    OpenCounter(+1);
    return SQLITE_OK;
  }
}


/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing.  To avoid
** a potential security problem, we do not allow the file to have
................................................................................
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
static int unixOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  int rc;
  OsFile f;

  assert( 0==*pId );
  if( access(zFilename, 0)==0 ){
    return SQLITE_CANTOPEN;
  }
  SET_THREADID(&f);
  f.dirfd = -1;
  f.h = open(zFilename,
                O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE|O_BINARY,
                SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( f.h<0 ){
    return SQLITE_CANTOPEN;
  }
  sqlite3OsEnterMutex();
  rc = findLockInfo(f.h, &f.pLock, &f.pOpen);
  sqlite3OsLeaveMutex();
  if( rc ){
    close(f.h);
    unlink(zFilename);
    return SQLITE_NOMEM;
  }
  f.locktype = 0;
  if( delFlag ){
    unlink(zFilename);
  }
  TRACE3("OPEN-EX %-3d %s\n", f.h, zFilename);
  *pId = allocateOsFile(&f);
  if( *pId==0 ){
    return SQLITE_NOMEM;
  }else{
    OpenCounter(+1);
    return SQLITE_OK;
  }
}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
static int unixOpenReadOnly(const char *zFilename, OsFile **pId){
  int rc;
  OsFile f;

  assert( 0==*pId );
  SET_THREADID(&f);
  f.dirfd = -1;
  f.h = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
  if( f.h<0 ){
    return SQLITE_CANTOPEN;
  }
  sqlite3OsEnterMutex();
  rc = findLockInfo(f.h, &f.pLock, &f.pOpen);
  sqlite3OsLeaveMutex();
  if( rc ){
    close(f.h);
    return SQLITE_NOMEM;
  }
  f.locktype = 0;
  TRACE3("OPEN-RO %-3d %s\n", f.h, zFilename);
  *pId = allocateOsFile(&f);
  if( *pId==0 ){
    return SQLITE_NOMEM;
  }else{
    OpenCounter(+1);
    return SQLITE_OK;
  }
}

/*
** Attempt to open a file descriptor for the directory that contains a
** file.  This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
................................................................................
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
static int unixOpenDirectory(
  const char *zDirname,
  OsFile *id

){

  if( id==0 ){
    /* Do not open the directory if the corresponding file is not already
    ** open. */
    return SQLITE_CANTOPEN;
  }
  SET_THREADID(id);
  assert( id->dirfd<0 );
  id->dirfd = open(zDirname, O_RDONLY|O_BINARY, 0);
  if( id->dirfd<0 ){
    return SQLITE_CANTOPEN; 
  }
  TRACE3("OPENDIR %-3d %s\n", id->dirfd, zDirname);
  return SQLITE_OK;
}

/*
** If the following global variable points to a string which is the
** name of a directory, then that directory will be used to store
** temporary files.
................................................................................
** wrong.
*/
static int unixRead(OsFile *id, void *pBuf, int amt){
  int got;
  assert( id );
  SimulateIOError(SQLITE_IOERR);
  TIMER_START;
  got = read(id->h, pBuf, amt);
  TIMER_END;
  TRACE5("READ    %-3d %5d %7d %d\n", id->h, got, last_page, TIMER_ELAPSED);

  SEEK(0);
  /* if( got<0 ) got = 0; */
  if( got==amt ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
................................................................................
static int unixWrite(OsFile *id, const void *pBuf, int amt){
  int wrote = 0;
  assert( id );
  assert( amt>0 );
  SimulateIOError(SQLITE_IOERR);
  SimulateDiskfullError;
  TIMER_START;
  while( amt>0 && (wrote = write(id->h, pBuf, amt))>0 ){
    amt -= wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  TIMER_END;
  TRACE5("WRITE   %-3d %5d %7d %d\n", id->h, wrote, last_page, TIMER_ELAPSED);

  SEEK(0);
  if( amt>0 ){
    return SQLITE_FULL;
  }
  return SQLITE_OK;
}

................................................................................
*/
static int unixSeek(OsFile *id, i64 offset){
  assert( id );
  SEEK(offset/1024 + 1);
#ifdef SQLITE_TEST
  if( offset ) SimulateDiskfullError
#endif
  lseek(id->h, offset, SEEK_SET);
  return SQLITE_OK;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
** that syncs and fullsyncs are occuring at the right times.
................................................................................
** If we do not do this and we encounter a power failure, the directory
** entry for the journal might not exist after we reboot.  The next
** SQLite to access the file will not know that the journal exists (because
** the directory entry for the journal was never created) and the transaction
** will not roll back - possibly leading to database corruption.
*/
static int unixSync(OsFile *id, int dataOnly){

  assert( id );
  SimulateIOError(SQLITE_IOERR);
  TRACE2("SYNC    %-3d\n", id->h);
  if( full_fsync(id->h, id->fullSync, dataOnly) ){

    return SQLITE_IOERR;
  }
  if( id->dirfd>=0 ){
    TRACE2("DIRSYNC %-3d\n", id->dirfd);
#ifndef SQLITE_DISABLE_DIRSYNC
    if( full_fsync(id->dirfd, id->fullSync, 0) ){

        return SQLITE_IOERR;
    }
#endif
    close(id->dirfd);  /* Only need to sync once, so close the directory */
    id->dirfd = -1;    /* when we are done. */
  }
  return SQLITE_OK;
}

/*
** Sync the directory zDirname. This is a no-op on operating systems other
** than UNIX.
................................................................................

/*
** Truncate an open file to a specified size
*/
static int unixTruncate(OsFile *id, i64 nByte){
  assert( id );
  SimulateIOError(SQLITE_IOERR);
  return ftruncate(id->h, nByte)==0 ? SQLITE_OK : SQLITE_IOERR;
}

/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(OsFile *id, i64 *pSize){
  struct stat buf;
  assert( id );
  SimulateIOError(SQLITE_IOERR);
  if( fstat(id->h, &buf)!=0 ){
    return SQLITE_IOERR;
  }
  *pSize = buf.st_size;
  return SQLITE_OK;
}

/*
................................................................................
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero.  If the file is unlocked or holds only SHARED locks, then
** return zero.
*/
static int unixCheckReservedLock(OsFile *id){
  int r = 0;


  assert( id );
  if( CHECK_THREADID(id) ) return SQLITE_MISUSE;
  sqlite3OsEnterMutex(); /* Needed because id->pLock is shared across threads */

  /* Check if a thread in this process holds such a lock */
  if( id->pLock->locktype>SHARED_LOCK ){
    r = 1;
  }

  /* Otherwise see if some other process holds it.
  */
  if( !r ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    fcntl(id->h, F_GETLK, &lock);
    if( lock.l_type!=F_UNLCK ){
      r = 1;
    }
  }
  
  sqlite3OsLeaveMutex();
  TRACE3("TEST WR-LOCK %d %d\n", id->h, r);

  return r;
}

#ifdef SQLITE_DEBUG
/*
** Helper function for printing out trace information from debugging
** binaries. This returns the string represetation of the supplied
** integer lock-type.
*/
static const char * locktypeName(int locktype){
  switch( locktype ){
  case NO_LOCK: return "NONE";
  case SHARED_LOCK: return "SHARED";
  case RESERVED_LOCK: return "RESERVED";
  case PENDING_LOCK: return "PENDING";
  case EXCLUSIVE_LOCK: return "EXCLUSIVE";
  }
................................................................................
  **
  ** The reason a single byte cannot be used instead of the 'shared byte
  ** range' is that some versions of windows do not support read-locks. By
  ** locking a random byte from a range, concurrent SHARED locks may exist
  ** even if the locking primitive used is always a write-lock.
  */
  int rc = SQLITE_OK;

  struct lockInfo *pLock = id->pLock;
  struct flock lock;
  int s;

  assert( id );
  TRACE7("LOCK    %d %s was %s(%s,%d) pid=%d\n", id->h, locktypeName(locktype), 

      locktypeName(id->locktype), locktypeName(pLock->locktype), pLock->cnt
      ,getpid() );
  if( CHECK_THREADID(id) ) return SQLITE_MISUSE;

  /* If there is already a lock of this type or more restrictive on the
  ** OsFile, do nothing. Don't use the end_lock: exit path, as
  ** sqlite3OsEnterMutex() hasn't been called yet.
  */
  if( id->locktype>=locktype ){
    TRACE3("LOCK    %d %s ok (already held)\n", id->h, locktypeName(locktype));

    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct
  */
  assert( id->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );
  assert( locktype!=RESERVED_LOCK || id->locktype==SHARED_LOCK );

  /* This mutex is needed because id->pLock is shared across threads
  */
  sqlite3OsEnterMutex();

  /* If some thread using this PID has a lock via a different OsFile*
  ** handle that precludes the requested lock, return BUSY.
  */
  if( (id->locktype!=pLock->locktype && 
          (pLock->locktype>=PENDING_LOCK || locktype>SHARED_LOCK))
  ){
    rc = SQLITE_BUSY;
    goto end_lock;
  }

  /* If a SHARED lock is requested, and some thread using this PID already
  ** has a SHARED or RESERVED lock, then increment reference counts and
  ** return SQLITE_OK.
  */
  if( locktype==SHARED_LOCK && 
      (pLock->locktype==SHARED_LOCK || pLock->locktype==RESERVED_LOCK) ){
    assert( locktype==SHARED_LOCK );
    assert( id->locktype==0 );
    assert( pLock->cnt>0 );
    id->locktype = SHARED_LOCK;
    pLock->cnt++;
    id->pOpen->nLock++;
    goto end_lock;
  }

  lock.l_len = 1L;

  lock.l_whence = SEEK_SET;

  /* A PENDING lock is needed before acquiring a SHARED lock and before
  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
  ** be released.
  */
  if( locktype==SHARED_LOCK 
      || (locktype==EXCLUSIVE_LOCK && id->locktype<PENDING_LOCK)
  ){
    lock.l_type = (locktype==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    s = fcntl(id->h, F_SETLK, &lock);
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
      goto end_lock;
    }
  }


................................................................................
  if( locktype==SHARED_LOCK ){
    assert( pLock->cnt==0 );
    assert( pLock->locktype==0 );

    /* Now get the read-lock */
    lock.l_start = SHARED_FIRST;
    lock.l_len = SHARED_SIZE;
    s = fcntl(id->h, F_SETLK, &lock);

    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( fcntl(id->h, F_SETLK, &lock)!=0 ){
      rc = SQLITE_IOERR;  /* This should never happen */
      goto end_lock;
    }
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
    }else{
      id->locktype = SHARED_LOCK;
      id->pOpen->nLock++;
      pLock->cnt = 1;
    }
  }else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){
    /* We are trying for an exclusive lock but another thread in this
    ** same process is still holding a shared lock. */
    rc = SQLITE_BUSY;
  }else{
    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    assert( 0!=id->locktype );
    lock.l_type = F_WRLCK;
    switch( locktype ){
      case RESERVED_LOCK:
        lock.l_start = RESERVED_BYTE;
        break;
      case EXCLUSIVE_LOCK:
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        break;
      default:
        assert(0);
    }
    s = fcntl(id->h, F_SETLK, &lock);
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
    }
  }
  
  if( rc==SQLITE_OK ){
    id->locktype = locktype;
    pLock->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    id->locktype = PENDING_LOCK;
    pLock->locktype = PENDING_LOCK;
  }

end_lock:
  sqlite3OsLeaveMutex();
  TRACE4("LOCK    %d %s %s\n", id->h, locktypeName(locktype), 
      rc==SQLITE_OK ? "ok" : "failed");
  return rc;
}

/*
** Lower the locking level on file descriptor id to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** It is not possible for this routine to fail if the second argument
** is NO_LOCK.  If the second argument is SHARED_LOCK, this routine
** might return SQLITE_IOERR instead of SQLITE_OK.
*/
static int unixUnlock(OsFile *id, int locktype){
  struct lockInfo *pLock;
  struct flock lock;
  int rc = SQLITE_OK;


  assert( id );
  TRACE7("UNLOCK  %d %d was %d(%d,%d) pid=%d\n", id->h, locktype, id->locktype, 
      id->pLock->locktype, id->pLock->cnt, getpid());

  if( CHECK_THREADID(id) ) return SQLITE_MISUSE;

  assert( locktype<=SHARED_LOCK );
  if( id->locktype<=locktype ){
    return SQLITE_OK;
  }
  sqlite3OsEnterMutex();
  pLock = id->pLock;
  assert( pLock->cnt!=0 );
  if( id->locktype>SHARED_LOCK ){
    assert( pLock->locktype==id->locktype );
    if( locktype==SHARED_LOCK ){
      lock.l_type = F_RDLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = SHARED_FIRST;
      lock.l_len = SHARED_SIZE;
      if( fcntl(id->h, F_SETLK, &lock)!=0 ){
        /* This should never happen */
        rc = SQLITE_IOERR;
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( fcntl(id->h, F_SETLK, &lock)==0 ){
      pLock->locktype = SHARED_LOCK;
    }else{
      rc = SQLITE_IOERR;  /* This should never happen */
    }
  }
  if( locktype==NO_LOCK ){
    struct openCnt *pOpen;
................................................................................
    ** the lock.
    */
    pLock->cnt--;
    if( pLock->cnt==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      if( fcntl(id->h, F_SETLK, &lock)==0 ){
        pLock->locktype = NO_LOCK;
      }else{
        rc = SQLITE_IOERR;  /* This should never happen */
      }
    }

    /* Decrement the count of locks against this same file.  When the
    ** count reaches zero, close any other file descriptors whose close
    ** was deferred because of outstanding locks.
    */
    pOpen = id->pOpen;
    pOpen->nLock--;
    assert( pOpen->nLock>=0 );
    if( pOpen->nLock==0 && pOpen->nPending>0 ){
      int i;
      for(i=0; i<pOpen->nPending; i++){
        close(pOpen->aPending[i]);
      }
      sqliteFree(pOpen->aPending);
      pOpen->nPending = 0;
      pOpen->aPending = 0;
    }
  }
  sqlite3OsLeaveMutex();
  id->locktype = locktype;
  return rc;
}

/*
** Close a file.
*/
static int unixClose(OsFile **pId){
  OsFile *id = *pId;
  if( !id ) return SQLITE_OK;
  if( CHECK_THREADID(id) ) return SQLITE_MISUSE;
  unixUnlock(id, NO_LOCK);
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  sqlite3OsEnterMutex();
  if( id->pOpen->nLock ){
    /* If there are outstanding locks, do not actually close the file just
    ** yet because that would clear those locks.  Instead, add the file
    ** descriptor to pOpen->aPending.  It will be automatically closed when
    ** the last lock is cleared.
    */
    int *aNew;
................................................................................
    }
  }else{
    /* There are no outstanding locks so we can close the file immediately */
    close(id->h);
  }
  releaseLockInfo(id->pLock);
  releaseOpenCnt(id->pOpen);
  sqlite3OsLeaveMutex();
  id->isOpen = 0;
  TRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  sqliteFree(id);
  *pId = 0;
  return SQLITE_OK;
}
................................................................................
  return zFull;
}

/*
** Change the value of the fullsync flag in the given file descriptor.
*/
static void unixSetFullSync(OsFile *id, int v){
  id->fullSync = v;
}

/*
** Return the underlying file handle for an OsFile
*/
static int unixFileHandle(OsFile *id){
  return id->h;
}

/*
** Return an integer that indices the type of lock currently held
** by this handle.  (Used for testing and analysis only.)
*/
static int unixLockState(OsFile *id){
  return id->locktype;
}

/*
** This is the structure that defines all of the I/O routines.

*/
struct sqlite3IoVtbl sqlite3Io = {
  unixDelete,
  unixFileExists,
  unixOpenReadWrite,
  unixOpenExclusive,
  unixOpenReadOnly,
  unixOpenDirectory,
  unixSyncDirectory,
  unixTempFileName,
  unixIsDirWritable,
  unixClose,
  unixRead,
  unixWrite,
  unixSeek,
  unixSync,
  unixTruncate,



  unixFileSize,
  unixFullPathname,
  unixLock,
  unixUnlock,
  unixCheckReservedLock,
  unixSetFullSync,
  unixFileHandle,
  unixLockState,

};























#endif /* SQLITE_OMIT_DISKIO */
/***************************************************************************
** Everything above deals with file I/O.  Everything that follows deals
** with other miscellanous aspects of the operating system interface
****************************************************************************/
................................................................................


/*
** Get information to seed the random number generator.  The seed
** is written into the buffer zBuf[256].  The calling function must
** supply a sufficiently large buffer.
*/
int sqlite3OsRandomSeed(char *zBuf){
  /* We have to initialize zBuf to prevent valgrind from reporting
  ** errors.  The reports issued by valgrind are incorrect - we would
  ** prefer that the randomness be increased by making use of the
  ** uninitialized space in zBuf - but valgrind errors tend to worry
  ** some users.  Rather than argue, it seems easier just to initialize
  ** the whole array and silence valgrind, even if that means less randomness
  ** in the random seed.
................................................................................
#endif
  return SQLITE_OK;
}

/*
** Sleep for a little while.  Return the amount of time slept.
*/
int sqlite3OsSleep(int ms){
#if defined(HAVE_USLEEP) && HAVE_USLEEP
  usleep(ms*1000);
  return ms;
#else
  sleep((ms+999)/1000);
  return 1000*((ms+999)/1000);
#endif
................................................................................
** The following pair of routine implement mutual exclusion for
** multi-threaded processes.  Only a single thread is allowed to
** executed code that is surrounded by EnterMutex() and LeaveMutex().
**
** SQLite uses only a single Mutex.  There is not much critical
** code and what little there is executes quickly and without blocking.
*/
void sqlite3OsEnterMutex(){
#ifdef SQLITE_UNIX_THREADS
  pthread_mutex_lock(&mutex);
#endif
  assert( !inMutex );
  inMutex = 1;
}
void sqlite3OsLeaveMutex(){
  assert( inMutex );
  inMutex = 0;
#ifdef SQLITE_UNIX_THREADS
  pthread_mutex_unlock(&mutex);
#endif
}

/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3OsCurrentTime().  This is used for testing.
*/
#ifdef SQLITE_TEST
int sqlite3_current_time = 0;
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
int sqlite3OsCurrentTime(double *prNow){
#ifdef NO_GETTOD
  time_t t;
  time(&t);
  *prNow = t/86400.0 + 2440587.5;
#else
  struct timeval sNow;
  struct timezone sTz;  /* Not used */
................................................................................
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  return 0;
}































#endif /* OS_UNIX */







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#ifndef SQLITE_DEFAULT_FILE_PERMISSIONS
# define SQLITE_DEFAULT_FILE_PERMISSIONS 0644
#endif



/*
** The unixFile structure is subclass of OsFile specific for the unix
** protability layer.





*/
typedef struct unixFile unixFile;
struct unixFile {
  IoMethod const *pMethod;  /* Always the first entry */
  struct openCnt *pOpen;    /* Info about all open fd's on this inode */
  struct lockInfo *pLock;   /* Info about locks on this inode */
  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
  unsigned char isOpen;     /* True if needs to be closed */
  unsigned char fullSync;   /* Use F_FULLSYNC if available */
  int dirfd;                /* File descriptor for the directory */
................................................................................
/*
** Return TRUE if the named file exists.
*/
static int unixFileExists(const char *zFilename){
  return access(zFilename, 0)==0;
}

/* Forward declaration */
static int allocateUnixFile(unixFile *pInit, OsFile **pId);














/*
** Attempt to open a file for both reading and writing.  If that
** fails, try opening it read-only.  If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id
................................................................................
*/
static int unixOpenReadWrite(
  const char *zFilename,
  OsFile **pId,
  int *pReadonly
){
  int rc;
  unixFile f;

  assert( 0==*pId );
  f.dirfd = -1;
  SET_THREADID(&f);
  f.h = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE|O_BINARY,
                          SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( f.h<0 ){
................................................................................
    if( f.h<0 ){
      return SQLITE_CANTOPEN; 
    }
    *pReadonly = 1;
  }else{
    *pReadonly = 0;
  }
  sqlite3Os.xEnterMutex();
  rc = findLockInfo(f.h, &f.pLock, &f.pOpen);
  sqlite3Os.xLeaveMutex();
  if( rc ){
    close(f.h);
    return SQLITE_NOMEM;
  }
  f.locktype = 0;
  TRACE3("OPEN    %-3d %s\n", f.h, zFilename);
  return allocateUnixFile(&f, pId);






}


/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing.  To avoid
** a potential security problem, we do not allow the file to have
................................................................................
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
static int unixOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  int rc;
  unixFile f;

  assert( 0==*pId );
  if( access(zFilename, 0)==0 ){
    return SQLITE_CANTOPEN;
  }
  SET_THREADID(&f);
  f.dirfd = -1;
  f.h = open(zFilename,
                O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE|O_BINARY,
                SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( f.h<0 ){
    return SQLITE_CANTOPEN;
  }
  sqlite3Os.xEnterMutex();
  rc = findLockInfo(f.h, &f.pLock, &f.pOpen);
  sqlite3Os.xLeaveMutex();
  if( rc ){
    close(f.h);
    unlink(zFilename);
    return SQLITE_NOMEM;
  }
  f.locktype = 0;
  if( delFlag ){
    unlink(zFilename);
  }
  TRACE3("OPEN-EX %-3d %s\n", f.h, zFilename);
  return allocateUnixFile(&f, pId);






}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
static int unixOpenReadOnly(const char *zFilename, OsFile **pId){
  int rc;
  unixFile f;

  assert( 0==*pId );
  SET_THREADID(&f);
  f.dirfd = -1;
  f.h = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
  if( f.h<0 ){
    return SQLITE_CANTOPEN;
  }
  sqlite3Os.xEnterMutex();
  rc = findLockInfo(f.h, &f.pLock, &f.pOpen);
  sqlite3Os.xLeaveMutex();
  if( rc ){
    close(f.h);
    return SQLITE_NOMEM;
  }
  f.locktype = 0;
  TRACE3("OPEN-RO %-3d %s\n", f.h, zFilename);
  return allocateUnixFile(&f, pId);






}

/*
** Attempt to open a file descriptor for the directory that contains a
** file.  This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
................................................................................
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
static int unixOpenDirectory(

  OsFile *id,
  const char *zDirname
){
  unixFile *pFile = (unixFile*)id;
  if( pFile==0 ){
    /* Do not open the directory if the corresponding file is not already
    ** open. */
    return SQLITE_CANTOPEN;
  }
  SET_THREADID(pFile);
  assert( pFile->dirfd<0 );
  pFile->dirfd = open(zDirname, O_RDONLY|O_BINARY, 0);
  if( pFile->dirfd<0 ){
    return SQLITE_CANTOPEN; 
  }
  TRACE3("OPENDIR %-3d %s\n", pFile->dirfd, zDirname);
  return SQLITE_OK;
}

/*
** If the following global variable points to a string which is the
** name of a directory, then that directory will be used to store
** temporary files.
................................................................................
** wrong.
*/
static int unixRead(OsFile *id, void *pBuf, int amt){
  int got;
  assert( id );
  SimulateIOError(SQLITE_IOERR);
  TIMER_START;
  got = read(((unixFile*)id)->h, pBuf, amt);
  TIMER_END;
  TRACE5("READ    %-3d %5d %7d %d\n", ((unixFile*)id)->h, got,
          last_page, TIMER_ELAPSED);
  SEEK(0);
  /* if( got<0 ) got = 0; */
  if( got==amt ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
................................................................................
static int unixWrite(OsFile *id, const void *pBuf, int amt){
  int wrote = 0;
  assert( id );
  assert( amt>0 );
  SimulateIOError(SQLITE_IOERR);
  SimulateDiskfullError;
  TIMER_START;
  while( amt>0 && (wrote = write(((unixFile*)id)->h, pBuf, amt))>0 ){
    amt -= wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  TIMER_END;
  TRACE5("WRITE   %-3d %5d %7d %d\n", ((unixFile*)id)->h, wrote,
          last_page, TIMER_ELAPSED);
  SEEK(0);
  if( amt>0 ){
    return SQLITE_FULL;
  }
  return SQLITE_OK;
}

................................................................................
*/
static int unixSeek(OsFile *id, i64 offset){
  assert( id );
  SEEK(offset/1024 + 1);
#ifdef SQLITE_TEST
  if( offset ) SimulateDiskfullError
#endif
  lseek(((unixFile*)id)->h, offset, SEEK_SET);
  return SQLITE_OK;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
** that syncs and fullsyncs are occuring at the right times.
................................................................................
** If we do not do this and we encounter a power failure, the directory
** entry for the journal might not exist after we reboot.  The next
** SQLite to access the file will not know that the journal exists (because
** the directory entry for the journal was never created) and the transaction
** will not roll back - possibly leading to database corruption.
*/
static int unixSync(OsFile *id, int dataOnly){
  unixFile *pFile = (unixFile*)id;
  assert( pFile );
  SimulateIOError(SQLITE_IOERR);
  TRACE2("SYNC    %-3d\n", pFile->h);

  if( full_fsync(pFile->h, pFile->fullSync, dataOnly) ){
    return SQLITE_IOERR;
  }
  if( pFile->dirfd>=0 ){
    TRACE2("DIRSYNC %-3d\n", pFile->dirfd);
#ifndef SQLITE_DISABLE_DIRSYNC

    if( full_fsync(pFile->dirfd, pFile->fullSync, 0) ){
        return SQLITE_IOERR;
    }
#endif
    close(pFile->dirfd);  /* Only need to sync once, so close the directory */
    pFile->dirfd = -1;    /* when we are done. */
  }
  return SQLITE_OK;
}

/*
** Sync the directory zDirname. This is a no-op on operating systems other
** than UNIX.
................................................................................

/*
** Truncate an open file to a specified size
*/
static int unixTruncate(OsFile *id, i64 nByte){
  assert( id );
  SimulateIOError(SQLITE_IOERR);
  return ftruncate(((unixFile*)id)->h, nByte)==0 ? SQLITE_OK : SQLITE_IOERR;
}

/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(OsFile *id, i64 *pSize){
  struct stat buf;
  assert( id );
  SimulateIOError(SQLITE_IOERR);
  if( fstat(((unixFile*)id)->h, &buf)!=0 ){
    return SQLITE_IOERR;
  }
  *pSize = buf.st_size;
  return SQLITE_OK;
}

/*
................................................................................
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero.  If the file is unlocked or holds only SHARED locks, then
** return zero.
*/
static int unixCheckReservedLock(OsFile *id){
  int r = 0;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  if( CHECK_THREADID(pFile) ) return SQLITE_MISUSE;
  sqlite3Os.xEnterMutex(); /* Because pFile->pLock is shared across threads */

  /* Check if a thread in this process holds such a lock */
  if( pFile->pLock->locktype>SHARED_LOCK ){
    r = 1;
  }

  /* Otherwise see if some other process holds it.
  */
  if( !r ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    fcntl(pFile->h, F_GETLK, &lock);
    if( lock.l_type!=F_UNLCK ){
      r = 1;
    }
  }
  
  sqlite3Os.xLeaveMutex();
  TRACE3("TEST WR-LOCK %d %d\n", pFile->h, r);

  return r;
}

#ifdef SQLITE_DEBUG
/*
** Helper function for printing out trace information from debugging
** binaries. This returns the string represetation of the supplied
** integer lock-type.
*/
static const char *locktypeName(int locktype){
  switch( locktype ){
  case NO_LOCK: return "NONE";
  case SHARED_LOCK: return "SHARED";
  case RESERVED_LOCK: return "RESERVED";
  case PENDING_LOCK: return "PENDING";
  case EXCLUSIVE_LOCK: return "EXCLUSIVE";
  }
................................................................................
  **
  ** The reason a single byte cannot be used instead of the 'shared byte
  ** range' is that some versions of windows do not support read-locks. By
  ** locking a random byte from a range, concurrent SHARED locks may exist
  ** even if the locking primitive used is always a write-lock.
  */
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  struct lockInfo *pLock = pFile->pLock;
  struct flock lock;
  int s;

  assert( pFile );
  TRACE7("LOCK    %d %s was %s(%s,%d) pid=%d\n", pFile->h,
      locktypeName(locktype), locktypeName(pFile->locktype),
      locktypeName(pLock->locktype), pLock->cnt , getpid());

  if( CHECK_THREADID(pFile) ) return SQLITE_MISUSE;

  /* If there is already a lock of this type or more restrictive on the
  ** OsFile, do nothing. Don't use the end_lock: exit path, as
  ** sqlite3Os.xEnterMutex() hasn't been called yet.
  */
  if( pFile->locktype>=locktype ){
    TRACE3("LOCK    %d %s ok (already held)\n", pFile->h,
            locktypeName(locktype));
    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct
  */
  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );
  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );

  /* This mutex is needed because pFile->pLock is shared across threads
  */
  sqlite3Os.xEnterMutex();

  /* If some thread using this PID has a lock via a different OsFile*
  ** handle that precludes the requested lock, return BUSY.
  */
  if( (pFile->locktype!=pLock->locktype && 
          (pLock->locktype>=PENDING_LOCK || locktype>SHARED_LOCK))
  ){
    rc = SQLITE_BUSY;
    goto end_lock;
  }

  /* If a SHARED lock is requested, and some thread using this PID already
  ** has a SHARED or RESERVED lock, then increment reference counts and
  ** return SQLITE_OK.
  */
  if( locktype==SHARED_LOCK && 
      (pLock->locktype==SHARED_LOCK || pLock->locktype==RESERVED_LOCK) ){
    assert( locktype==SHARED_LOCK );
    assert( pFile->locktype==0 );
    assert( pLock->cnt>0 );
    pFile->locktype = SHARED_LOCK;
    pLock->cnt++;
    pFile->pOpen->nLock++;
    goto end_lock;
  }

  lock.l_len = 1L;

  lock.l_whence = SEEK_SET;

  /* A PENDING lock is needed before acquiring a SHARED lock and before
  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
  ** be released.
  */
  if( locktype==SHARED_LOCK 
      || (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
  ){
    lock.l_type = (locktype==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
      goto end_lock;
    }
  }


................................................................................
  if( locktype==SHARED_LOCK ){
    assert( pLock->cnt==0 );
    assert( pLock->locktype==0 );

    /* Now get the read-lock */
    lock.l_start = SHARED_FIRST;
    lock.l_len = SHARED_SIZE;
    s = fcntl(pFile->h, F_SETLK, &lock);

    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( fcntl(pFile->h, F_SETLK, &lock)!=0 ){
      rc = SQLITE_IOERR;  /* This should never happen */
      goto end_lock;
    }
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
    }else{
      pFile->locktype = SHARED_LOCK;
      pFile->pOpen->nLock++;
      pLock->cnt = 1;
    }
  }else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){
    /* We are trying for an exclusive lock but another thread in this
    ** same process is still holding a shared lock. */
    rc = SQLITE_BUSY;
  }else{
    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    assert( 0!=pFile->locktype );
    lock.l_type = F_WRLCK;
    switch( locktype ){
      case RESERVED_LOCK:
        lock.l_start = RESERVED_BYTE;
        break;
      case EXCLUSIVE_LOCK:
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        break;
      default:
        assert(0);
    }
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
    }
  }
  
  if( rc==SQLITE_OK ){
    pFile->locktype = locktype;
    pLock->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;
    pLock->locktype = PENDING_LOCK;
  }

end_lock:
  sqlite3Os.xLeaveMutex();
  TRACE4("LOCK    %d %s %s\n", pFile->h, locktypeName(locktype), 
      rc==SQLITE_OK ? "ok" : "failed");
  return rc;
}

/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** It is not possible for this routine to fail if the second argument
** is NO_LOCK.  If the second argument is SHARED_LOCK, this routine
** might return SQLITE_IOERR instead of SQLITE_OK.
*/
static int unixUnlock(OsFile *id, int locktype){
  struct lockInfo *pLock;
  struct flock lock;
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  TRACE7("UNLOCK  %d %d was %d(%d,%d) pid=%d\n", pFile->h, locktype,

      pFile->locktype, pFile->pLock->locktype, pFile->pLock->cnt, getpid());
  if( CHECK_THREADID(pFile) ) return SQLITE_MISUSE;

  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  sqlite3Os.xEnterMutex();
  pLock = pFile->pLock;
  assert( pLock->cnt!=0 );
  if( pFile->locktype>SHARED_LOCK ){
    assert( pLock->locktype==pFile->locktype );
    if( locktype==SHARED_LOCK ){
      lock.l_type = F_RDLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = SHARED_FIRST;
      lock.l_len = SHARED_SIZE;
      if( fcntl(pFile->h, F_SETLK, &lock)!=0 ){
        /* This should never happen */
        rc = SQLITE_IOERR;
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( fcntl(pFile->h, F_SETLK, &lock)==0 ){
      pLock->locktype = SHARED_LOCK;
    }else{
      rc = SQLITE_IOERR;  /* This should never happen */
    }
  }
  if( locktype==NO_LOCK ){
    struct openCnt *pOpen;
................................................................................
    ** the lock.
    */
    pLock->cnt--;
    if( pLock->cnt==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      if( fcntl(pFile->h, F_SETLK, &lock)==0 ){
        pLock->locktype = NO_LOCK;
      }else{
        rc = SQLITE_IOERR;  /* This should never happen */
      }
    }

    /* Decrement the count of locks against this same file.  When the
    ** count reaches zero, close any other file descriptors whose close
    ** was deferred because of outstanding locks.
    */
    pOpen = pFile->pOpen;
    pOpen->nLock--;
    assert( pOpen->nLock>=0 );
    if( pOpen->nLock==0 && pOpen->nPending>0 ){
      int i;
      for(i=0; i<pOpen->nPending; i++){
        close(pOpen->aPending[i]);
      }
      sqliteFree(pOpen->aPending);
      pOpen->nPending = 0;
      pOpen->aPending = 0;
    }
  }
  sqlite3Os.xLeaveMutex();
  pFile->locktype = locktype;
  return rc;
}

/*
** Close a file.
*/
static int unixClose(OsFile **pId){
  unixFile *id = (unixFile*)*pId;
  if( !id ) return SQLITE_OK;
  if( CHECK_THREADID(id) ) return SQLITE_MISUSE;
  unixUnlock(*pId, NO_LOCK);
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  sqlite3Os.xEnterMutex();
  if( id->pOpen->nLock ){
    /* If there are outstanding locks, do not actually close the file just
    ** yet because that would clear those locks.  Instead, add the file
    ** descriptor to pOpen->aPending.  It will be automatically closed when
    ** the last lock is cleared.
    */
    int *aNew;
................................................................................
    }
  }else{
    /* There are no outstanding locks so we can close the file immediately */
    close(id->h);
  }
  releaseLockInfo(id->pLock);
  releaseOpenCnt(id->pOpen);
  sqlite3Os.xLeaveMutex();
  id->isOpen = 0;
  TRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  sqliteFree(id);
  *pId = 0;
  return SQLITE_OK;
}
................................................................................
  return zFull;
}

/*
** Change the value of the fullsync flag in the given file descriptor.
*/
static void unixSetFullSync(OsFile *id, int v){
  ((unixFile*)id)->fullSync = v;
}

/*
** Return the underlying file handle for an OsFile
*/
static int unixFileHandle(OsFile *id){
  return ((unixFile*)id)->h;
}

/*
** Return an integer that indices the type of lock currently held
** by this handle.  (Used for testing and analysis only.)
*/
static int unixLockState(OsFile *id){
  return ((unixFile*)id)->locktype;
}

/*
** This vector defines all the methods that can operate on an OsFile
** for unix.
*/

static const IoMethod sqlite3UnixIoMethod = {
  unixClose,



  unixOpenDirectory,




  unixRead,
  unixWrite,
  unixSeek,

  unixTruncate,
  unixSync,
  unixSetFullSync,
  unixFileHandle,
  unixFileSize,

  unixLock,
  unixUnlock,



  unixLockState,
  unixCheckReservedLock,
};

/*
** Allocate memory for a unixFile.  Initialize the new unixFile
** to the value given in pInit and return a pointer to the new
** OsFile.  If we run out of memory, close the file and return NULL.
*/
static int allocateUnixFile(unixFile *pInit, OsFile **pId){
  unixFile *pNew;
  pNew = sqliteMalloc( sizeof(unixFile) );
  if( pNew==0 ){
    close(pInit->h);
    *pId = 0;
    return SQLITE_NOMEM;
  }else{
    *pNew = *pInit;
    pNew->pMethod = &sqlite3UnixIoMethod;
    *pId = (OsFile*)pNew;
    OpenCounter(+1);
    return SQLITE_OK;
  }
}


#endif /* SQLITE_OMIT_DISKIO */
/***************************************************************************
** Everything above deals with file I/O.  Everything that follows deals
** with other miscellanous aspects of the operating system interface
****************************************************************************/
................................................................................


/*
** Get information to seed the random number generator.  The seed
** is written into the buffer zBuf[256].  The calling function must
** supply a sufficiently large buffer.
*/
static int unixRandomSeed(char *zBuf){
  /* We have to initialize zBuf to prevent valgrind from reporting
  ** errors.  The reports issued by valgrind are incorrect - we would
  ** prefer that the randomness be increased by making use of the
  ** uninitialized space in zBuf - but valgrind errors tend to worry
  ** some users.  Rather than argue, it seems easier just to initialize
  ** the whole array and silence valgrind, even if that means less randomness
  ** in the random seed.
................................................................................
#endif
  return SQLITE_OK;
}

/*
** Sleep for a little while.  Return the amount of time slept.
*/
static int unixSleep(int ms){
#if defined(HAVE_USLEEP) && HAVE_USLEEP
  usleep(ms*1000);
  return ms;
#else
  sleep((ms+999)/1000);
  return 1000*((ms+999)/1000);
#endif
................................................................................
** The following pair of routine implement mutual exclusion for
** multi-threaded processes.  Only a single thread is allowed to
** executed code that is surrounded by EnterMutex() and LeaveMutex().
**
** SQLite uses only a single Mutex.  There is not much critical
** code and what little there is executes quickly and without blocking.
*/
static void unixEnterMutex(){
#ifdef SQLITE_UNIX_THREADS
  pthread_mutex_lock(&mutex);
#endif
  assert( !inMutex );
  inMutex = 1;
}
static void unixLeaveMutex(){
  assert( inMutex );
  inMutex = 0;
#ifdef SQLITE_UNIX_THREADS
  pthread_mutex_unlock(&mutex);
#endif
}

/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3Os.xCurrentTime().  This is used for testing.
*/
#ifdef SQLITE_TEST
int sqlite3_current_time = 0;
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
static int unixCurrentTime(double *prNow){
#ifdef NO_GETTOD
  time_t t;
  time(&t);
  *prNow = t/86400.0 + 2440587.5;
#else
  struct timeval sNow;
  struct timezone sTz;  /* Not used */
................................................................................
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  return 0;
}

/* Macro used to comment out routines that do not exists when there is
** no disk I/O */
#ifdef SQLITE_OMIT_DISKIO
# define IF_DISKIO(X)  0
#else
# define IF_DISKIO(X)  X
#endif

/*
** This is the structure that defines all of the I/O routines.
*/
struct sqlite3OsVtbl sqlite3Os = {
  IF_DISKIO( unixOpenReadWrite ),
  IF_DISKIO( unixOpenExclusive ),
  IF_DISKIO( unixOpenReadOnly ),
  IF_DISKIO( unixDelete ),
  IF_DISKIO( unixFileExists ),
  IF_DISKIO( unixFullPathname ),
  IF_DISKIO( unixIsDirWritable ),
  IF_DISKIO( unixSyncDirectory ),
  IF_DISKIO( unixTempFileName ),
  unixRandomSeed,
  unixSleep,
  unixCurrentTime,
  unixEnterMutex,
  unixLeaveMutex,
};



#endif /* OS_UNIX */

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/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"

/*
** The OsFile structure is a operating-system independing representation
** of an open file handle.  It is defined differently for each architecture.
**
** This is the definition for Win32.
*/
struct OsFile {
  HANDLE h;               /* Handle for accessing the file */
  unsigned char locktype; /* Type of lock currently held on this file */
  short sharedLockByte;   /* Randomly chosen byte used as a shared lock */
};



/*
** Do not include any of the File I/O interface procedures if the
** SQLITE_OMIT_DISKIO macro is defined (indicating that there database
** will be in-memory only)
*/
................................................................................
    sqliteFree(zWide);
  }else{
    exists = GetFileAttributesA(zFilename) != 0xffffffff;
  }
  return exists;
}



/*
** Allocate memory for an OsFile.  Initialize the new OsFile
** to the value given in pInit and return a pointer to the new
** OsFile.  If we run out of memory, close the file and return NULL.
*/
static OsFile *allocateOsFile(OsFile *pInit){
  OsFile *pNew;
  pNew = sqliteMalloc( sizeof(OsFile) );
  if( pNew==0 ){
    CloseHandle(pInit->h);
  }else{
    *pNew = *pInit;
  }
  return pNew;
}

/*
** Attempt to open a file for both reading and writing.  If that
** fails, try opening it read-only.  If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id
................................................................................
** *id and *pReadonly unchanged.
*/
static int winOpenReadWrite(
  const char *zFilename,
  OsFile **pId,
  int *pReadonly
){
  OsFile f;
  HANDLE h;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId==0 );
  if( zWide ){
    h = CreateFileW(zWide,
       GENERIC_READ | GENERIC_WRITE,
       FILE_SHARE_READ | FILE_SHARE_WRITE,
................................................................................
      *pReadonly = 0;
    }
  }
  f.h = h;
  f.locktype = NO_LOCK;
  f.sharedLockByte = 0;
  TRACE3("OPEN R/W %d \"%s\"\n", h, zFilename);
  *pId = allocateOsFile(&f);
  if( *pId==0 ){
    return SQLITE_NOMEM;
  }else{
    OpenCounter(+1);
    return SQLITE_OK;
  }
}


/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing.  To avoid
** a potential security problem, we do not allow the file to have
................................................................................
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
static int winOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  OsFile f;
  HANDLE h;
  int fileflags;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId == 0 );
  if( delFlag ){
    fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS 
                     | FILE_FLAG_DELETE_ON_CLOSE;
................................................................................
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  f.h = h;
  f.locktype = NO_LOCK;
  f.sharedLockByte = 0;
  TRACE3("OPEN EX %d \"%s\"\n", h, zFilename);
  *pId = allocateOsFile(&f);
  if( *pId==0 ){
    return SQLITE_NOMEM;
  }else{
    OpenCounter(+1);
    return SQLITE_OK;
  }
}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
static int winOpenReadOnly(const char *zFilename, OsFile **pId){
  OsFile f;
  HANDLE h;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId==0 );
  if( zWide ){
    h = CreateFileW(zWide,
       GENERIC_READ,
       0,
................................................................................
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  f.h = h;
  f.locktype = NO_LOCK;
  f.sharedLockByte = 0;
  TRACE3("OPEN RO %d \"%s\"\n", h, zFilename);
  *pId = allocateOsFile(&f);
  if( *pId==0 ){
    return SQLITE_NOMEM;
  }else{
    OpenCounter(+1);
    return SQLITE_OK;
  }
}

/*
** Attempt to open a file descriptor for the directory that contains a
** file.  This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
................................................................................
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
static int winOpenDirectory(
  const char *zDirname,
  OsFile *id

){
  return SQLITE_OK;
}

/*
** If the following global variable points to a string which is the
** name of a directory, then that directory will be used to store
................................................................................
    sprintf(zBuf, "%s\\"TEMP_FILE_PREFIX, zTempPath);
    j = strlen(zBuf);
    sqlite3Randomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
    if( !sqlite3Io.xFileExists(zBuf) ) break;
  }
  TRACE2("TEMP FILENAME: %s\n", zBuf);
  return SQLITE_OK; 
}

/*
** Close a file.
*/
static int winClose(OsFile **pId){
  if( *pId ){

    TRACE2("CLOSE %d\n", (*pId)->h);
    CloseHandle((*pId)->h);
    OpenCounter(-1);
    sqliteFree(*pId);
    *pId = 0;
  }
  return SQLITE_OK;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
................................................................................
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int winRead(OsFile *id, void *pBuf, int amt){
  DWORD got;
  assert( id!=0 );
  SimulateIOError(SQLITE_IOERR);
  TRACE3("READ %d lock=%d\n", id->h, id->locktype);
  if( !ReadFile(id->h, pBuf, amt, &got, 0) ){
    got = 0;
  }
  if( got==(DWORD)amt ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
................................................................................
*/
static int winWrite(OsFile *id, const void *pBuf, int amt){
  int rc = 0;
  DWORD wrote;
  assert( id!=0 );
  SimulateIOError(SQLITE_IOERR);
  SimulateDiskfullError;
  TRACE3("WRITE %d lock=%d\n", id->h, id->locktype);
  assert( amt>0 );
  while( amt>0 && (rc = WriteFile(id->h, pBuf, amt, &wrote, 0))!=0 && wrote>0 ){

    amt -= wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  if( !rc || amt>(int)wrote ){
    return SQLITE_FULL;
  }
  return SQLITE_OK;
................................................................................
  LONG lowerBits = offset & 0xffffffff;
  DWORD rc;
  assert( id!=0 );
#ifdef SQLITE_TEST
  if( offset ) SimulateDiskfullError
#endif
  SEEK(offset/1024 + 1);
  rc = SetFilePointer(id->h, lowerBits, &upperBits, FILE_BEGIN);
  TRACE3("SEEK %d %lld\n", id->h, offset);
  if( rc==INVALID_SET_FILE_POINTER && GetLastError()!=NO_ERROR ){
    return SQLITE_FULL;
  }
  return SQLITE_OK;
}

/*
** Make sure all writes to a particular file are committed to disk.
*/
static int winSync(OsFile *id, int dataOnly){
  assert( id!=0 );
  TRACE3("SYNC %d lock=%d\n", id->h, id->locktype);
  if( FlushFileBuffers(id->h) ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
}

/*
................................................................................

/*
** Truncate an open file to a specified size
*/
static int winTruncate(OsFile *id, i64 nByte){
  LONG upperBits = nByte>>32;
  assert( id!=0 );
  TRACE3("TRUNCATE %d %lld\n", id->h, nByte);
  SimulateIOError(SQLITE_IOERR);
  SetFilePointer(id->h, nByte, &upperBits, FILE_BEGIN);
  SetEndOfFile(id->h);
  return SQLITE_OK;
}

/*
** Determine the current size of a file in bytes
*/
static int winFileSize(OsFile *id, i64 *pSize){
  DWORD upperBits, lowerBits;
  assert( id!=0 );
  SimulateIOError(SQLITE_IOERR);
  lowerBits = GetFileSize(id->h, &upperBits);
  *pSize = (((i64)upperBits)<<32) + lowerBits;
  return SQLITE_OK;
}

/*
** Acquire a reader lock.
** Different API routines are called depending on whether or not this
** is Win95 or WinNT.
*/
static int getReadLock(OsFile *id){
  int res;
  if( isNT() ){
    OVERLAPPED ovlp;
    ovlp.Offset = SHARED_FIRST;
    ovlp.OffsetHigh = 0;
    ovlp.hEvent = 0;
    res = LockFileEx(id->h, LOCKFILE_FAIL_IMMEDIATELY, 0, SHARED_SIZE,0,&ovlp);
................................................................................
  }
  return res;
}

/*
** Undo a readlock
*/
static int unlockReadLock(OsFile *id){
  int res;
  if( isNT() ){
    res = UnlockFile(id->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
  }else{
    res = UnlockFile(id->h, SHARED_FIRST + id->sharedLockByte, 0, 1, 0);
  }
  return res;
}

#ifndef SQLITE_OMIT_PAGER_PRAGMAS
/*
** Check that a given pathname is a directory and is writable 
................................................................................
** must go straight to locking level 0.
*/
static int winLock(OsFile *id, int locktype){
  int rc = SQLITE_OK;    /* Return code from subroutines */
  int res = 1;           /* Result of a windows lock call */
  int newLocktype;       /* Set id->locktype to this value before exiting */
  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */


  assert( id!=0 );
  TRACE5("LOCK %d %d was %d(%d)\n",
          id->h, locktype, id->locktype, id->sharedLockByte);


  /* If there is already a lock of this type or more restrictive on the
  ** OsFile, do nothing. Don't use the end_lock: exit path, as
  ** sqlite3OsEnterMutex() hasn't been called yet.
  */
  if( id->locktype>=locktype ){
    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct
  */
  assert( id->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );
  assert( locktype!=RESERVED_LOCK || id->locktype==SHARED_LOCK );

  /* Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or
  ** a SHARED lock.  If we are acquiring a SHARED lock, the acquisition of
  ** the PENDING_LOCK byte is temporary.
  */
  newLocktype = id->locktype;
  if( id->locktype==NO_LOCK
   || (locktype==EXCLUSIVE_LOCK && id->locktype==RESERVED_LOCK)
  ){
    int cnt = 3;
    while( cnt-->0 && (res = LockFile(id->h, PENDING_BYTE, 0, 1, 0))==0 ){
      /* Try 3 times to get the pending lock.  The pending lock might be
      ** held by another reader process who will release it momentarily.
      */
      TRACE2("could not get a PENDING lock. cnt=%d\n", cnt);
      Sleep(1);
    }
    gotPendingLock = res;
  }

  /* Acquire a shared lock
  */
  if( locktype==SHARED_LOCK && res ){
    assert( id->locktype==NO_LOCK );
    res = getReadLock(id);
    if( res ){
      newLocktype = SHARED_LOCK;
    }
  }

  /* Acquire a RESERVED lock
  */
  if( locktype==RESERVED_LOCK && res ){
    assert( id->locktype==SHARED_LOCK );
    res = LockFile(id->h, RESERVED_BYTE, 0, 1, 0);
    if( res ){
      newLocktype = RESERVED_LOCK;
    }
  }

  /* Acquire a PENDING lock
  */
................................................................................
    newLocktype = PENDING_LOCK;
    gotPendingLock = 0;
  }

  /* Acquire an EXCLUSIVE lock
  */
  if( locktype==EXCLUSIVE_LOCK && res ){
    assert( id->locktype>=SHARED_LOCK );
    res = unlockReadLock(id);
    TRACE2("unreadlock = %d\n", res);
    res = LockFile(id->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
    if( res ){
      newLocktype = EXCLUSIVE_LOCK;
    }else{
      TRACE2("error-code = %d\n", GetLastError());
    }
  }

  /* If we are holding a PENDING lock that ought to be released, then
  ** release it now.
  */
  if( gotPendingLock && locktype==SHARED_LOCK ){
    UnlockFile(id->h, PENDING_BYTE, 0, 1, 0);
  }

  /* Update the state of the lock has held in the file descriptor then
  ** return the appropriate result code.
  */
  if( res ){
    rc = SQLITE_OK;
  }else{
    TRACE4("LOCK FAILED %d trying for %d but got %d\n", id->h,
           locktype, newLocktype);
    rc = SQLITE_BUSY;
  }
  id->locktype = newLocktype;
  return rc;
}

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero, otherwise zero.
*/
static int winCheckReservedLock(OsFile *id){
  int rc;

  assert( id!=0 );
  if( id->locktype>=RESERVED_LOCK ){
    rc = 1;
    TRACE3("TEST WR-LOCK %d %d (local)\n", id->h, rc);
  }else{
    rc = LockFile(id->h, RESERVED_BYTE, 0, 1, 0);
    if( rc ){
      UnlockFile(id->h, RESERVED_BYTE, 0, 1, 0);
    }
    rc = !rc;
    TRACE3("TEST WR-LOCK %d %d (remote)\n", id->h, rc);
  }
  return rc;
}

/*
** Lower the locking level on file descriptor id to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
................................................................................
** It is not possible for this routine to fail if the second argument
** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
** might return SQLITE_IOERR;
*/
static int winUnlock(OsFile *id, int locktype){
  int type;
  int rc = SQLITE_OK;

  assert( id!=0 );
  assert( locktype<=SHARED_LOCK );
  TRACE5("UNLOCK %d to %d was %d(%d)\n", id->h, locktype,
          id->locktype, id->sharedLockByte);
  type = id->locktype;
  if( type>=EXCLUSIVE_LOCK ){
    UnlockFile(id->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
    if( locktype==SHARED_LOCK && !getReadLock(id) ){
      /* This should never happen.  We should always be able to
      ** reacquire the read lock */
      rc = SQLITE_IOERR;
    }
  }
  if( type>=RESERVED_LOCK ){
    UnlockFile(id->h, RESERVED_BYTE, 0, 1, 0);
  }
  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
    unlockReadLock(id);
  }
  if( type>=PENDING_LOCK ){
    UnlockFile(id->h, PENDING_BYTE, 0, 1, 0);
  }
  id->locktype = locktype;
  return rc;
}

/*
** Turn a relative pathname into a full pathname.  Return a pointer
** to the full pathname stored in space obtained from sqliteMalloc().
** The calling function is responsible for freeing this space once it
................................................................................
  return;
}

/*
** Return the underlying file handle for an OsFile
*/
static int winFileHandle(OsFile *id){
  return (int)id->h;
}

/*
** Return an integer that indices the type of lock currently held
** by this handle.  (Used for testing and analysis only.)
*/
static int winLockState(OsFile *id){
  return id->locktype;
}


/*

** This is the structure that defines all of the I/O routines.
*/
struct sqlite3IoVtbl sqlite3Io = {
  winDelete,
  winFileExists,
  winOpenReadWrite,
  winOpenExclusive,
  winOpenReadOnly,
  winOpenDirectory,
  winSyncDirectory,
  winTempFileName,
  winIsDirWritable,
  winClose,
  winRead,
  winWrite,
  winSeek,
  winSync,
  winTruncate,



  winFileSize,
  winFullPathname,
  winLock,
  winUnlock,
  winCheckReservedLock,
  winSetFullSync,
  winFileHandle,
  winLockState,

};






















#endif /* SQLITE_OMIT_DISKIO */
/***************************************************************************
** Everything above deals with file I/O.  Everything that follows deals
** with other miscellanous aspects of the operating system interface
****************************************************************************/

/*
** Get information to seed the random number generator.  The seed
** is written into the buffer zBuf[256].  The calling function must
** supply a sufficiently large buffer.
*/
int sqlite3OsRandomSeed(char *zBuf){
  /* We have to initialize zBuf to prevent valgrind from reporting
  ** errors.  The reports issued by valgrind are incorrect - we would
  ** prefer that the randomness be increased by making use of the
  ** uninitialized space in zBuf - but valgrind errors tend to worry
  ** some users.  Rather than argue, it seems easier just to initialize
  ** the whole array and silence valgrind, even if that means less randomness
  ** in the random seed.
................................................................................
  GetSystemTime((LPSYSTEMTIME)zBuf);
  return SQLITE_OK;
}

/*
** Sleep for a little while.  Return the amount of time slept.
*/
int sqlite3OsSleep(int ms){
  Sleep(ms);
  return ms;
}

/*
** Static variables used for thread synchronization
*/
................................................................................
** The following pair of routine implement mutual exclusion for
** multi-threaded processes.  Only a single thread is allowed to
** executed code that is surrounded by EnterMutex() and LeaveMutex().
**
** SQLite uses only a single Mutex.  There is not much critical
** code and what little there is executes quickly and without blocking.
*/
void sqlite3OsEnterMutex(){
#ifdef SQLITE_W32_THREADS
  static int isInit = 0;
  while( !isInit ){
    static long lock = 0;
    if( InterlockedIncrement(&lock)==1 ){
      InitializeCriticalSection(&cs);
      isInit = 1;
................................................................................
    }
  }
  EnterCriticalSection(&cs);
#endif
  assert( !inMutex );
  inMutex = 1;
}
void sqlite3OsLeaveMutex(){
  assert( inMutex );
  inMutex = 0;
#ifdef SQLITE_W32_THREADS
  LeaveCriticalSection(&cs);
#endif
}

................................................................................
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
int sqlite3OsCurrentTime(double *prNow){
  FILETIME ft;
  /* FILETIME structure is a 64-bit value representing the number of 
     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5). 
  */
  double now;
  GetSystemTimeAsFileTime( &ft );
  now = ((double)ft.dwHighDateTime) * 4294967296.0; 
................................................................................
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  return 0;
}






























#endif /* OS_WIN */







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/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"

/*
** The winFile structure is a subclass of OsFile specific to the win32
** portability layer.
*/
typedef struct winFile winFile;
struct winFile {
  IoMethod const *pMethod;/* Must be first */
  HANDLE h;               /* Handle for accessing the file */
  unsigned char locktype; /* Type of lock currently held on this file */
  short sharedLockByte;   /* Randomly chosen byte used as a shared lock */
};



/*
** Do not include any of the File I/O interface procedures if the
** SQLITE_OMIT_DISKIO macro is defined (indicating that there database
** will be in-memory only)
*/
................................................................................
    sqliteFree(zWide);
  }else{
    exists = GetFileAttributesA(zFilename) != 0xffffffff;
  }
  return exists;
}


/* Forward declaration */
int allocateWinFile(winFile *pInit, OsFile **pId);















/*
** Attempt to open a file for both reading and writing.  If that
** fails, try opening it read-only.  If the file does not exist,
** try to create it.
**
** On success, a handle for the open file is written to *id
................................................................................
** *id and *pReadonly unchanged.
*/
static int winOpenReadWrite(
  const char *zFilename,
  OsFile **pId,
  int *pReadonly
){
  winFile f;
  HANDLE h;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId==0 );
  if( zWide ){
    h = CreateFileW(zWide,
       GENERIC_READ | GENERIC_WRITE,
       FILE_SHARE_READ | FILE_SHARE_WRITE,
................................................................................
      *pReadonly = 0;
    }
  }
  f.h = h;
  f.locktype = NO_LOCK;
  f.sharedLockByte = 0;
  TRACE3("OPEN R/W %d \"%s\"\n", h, zFilename);
  return allocateWinFile(&f, pId);






}


/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing.  To avoid
** a potential security problem, we do not allow the file to have
................................................................................
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
static int winOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  winFile f;
  HANDLE h;
  int fileflags;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId == 0 );
  if( delFlag ){
    fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS 
                     | FILE_FLAG_DELETE_ON_CLOSE;
................................................................................
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  f.h = h;
  f.locktype = NO_LOCK;
  f.sharedLockByte = 0;
  TRACE3("OPEN EX %d \"%s\"\n", h, zFilename);
  return allocateWinFile(&f, pId);






}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
static int winOpenReadOnly(const char *zFilename, OsFile **pId){
  winFile f;
  HANDLE h;
  WCHAR *zWide = utf8ToUnicode(zFilename);
  assert( *pId==0 );
  if( zWide ){
    h = CreateFileW(zWide,
       GENERIC_READ,
       0,
................................................................................
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  f.h = h;
  f.locktype = NO_LOCK;
  f.sharedLockByte = 0;
  TRACE3("OPEN RO %d \"%s\"\n", h, zFilename);
  return allocateWinFile(&f, pId);






}

/*
** Attempt to open a file descriptor for the directory that contains a
** file.  This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
................................................................................
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
static int winOpenDirectory(

  OsFile *id,
  const char *zDirname
){
  return SQLITE_OK;
}

/*
** If the following global variable points to a string which is the
** name of a directory, then that directory will be used to store
................................................................................
    sprintf(zBuf, "%s\\"TEMP_FILE_PREFIX, zTempPath);
    j = strlen(zBuf);
    sqlite3Randomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
    if( !sqlite3Os.xFileExists(zBuf) ) break;
  }
  TRACE2("TEMP FILENAME: %s\n", zBuf);
  return SQLITE_OK; 
}

/*
** Close a file.
*/
static int winClose(OsFile **pId){
  winFile *pFile;
  if( pId && (pFile = (winFile*)*pId)!=0 ){
    TRACE2("CLOSE %d\n", pFile->h);
    CloseHandle(pFile->h);
    OpenCounter(-1);
    sqliteFree(pFile);
    *pId = 0;
  }
  return SQLITE_OK;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
................................................................................
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int winRead(OsFile *id, void *pBuf, int amt){
  DWORD got;
  assert( id!=0 );
  SimulateIOError(SQLITE_IOERR);
  TRACE3("READ %d lock=%d\n", ((winFile*)id)->h, ((winFile*)id)->locktype);
  if( !ReadFile(((winFile*)id)->h, pBuf, amt, &got, 0) ){
    got = 0;
  }
  if( got==(DWORD)amt ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
................................................................................
*/
static int winWrite(OsFile *id, const void *pBuf, int amt){
  int rc = 0;
  DWORD wrote;
  assert( id!=0 );
  SimulateIOError(SQLITE_IOERR);
  SimulateDiskfullError;
  TRACE3("WRITE %d lock=%d\n", ((winFile*)id)->h, ((winFile*)id)->locktype);
  assert( amt>0 );
  while( amt>0 && (rc = WriteFile(((winFile*)id)->h, pBuf, amt, &wrote, 0))!=0
         && wrote>0 ){
    amt -= wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  if( !rc || amt>(int)wrote ){
    return SQLITE_FULL;
  }
  return SQLITE_OK;
................................................................................
  LONG lowerBits = offset & 0xffffffff;
  DWORD rc;
  assert( id!=0 );
#ifdef SQLITE_TEST
  if( offset ) SimulateDiskfullError
#endif
  SEEK(offset/1024 + 1);
  rc = SetFilePointer(((winFile*)id)->h, lowerBits, &upperBits, FILE_BEGIN);
  TRACE3("SEEK %d %lld\n", ((winFile*)id)->h, offset);
  if( rc==INVALID_SET_FILE_POINTER && GetLastError()!=NO_ERROR ){
    return SQLITE_FULL;
  }
  return SQLITE_OK;
}

/*
** Make sure all writes to a particular file are committed to disk.
*/
static int winSync(OsFile *id, int dataOnly){
  assert( id!=0 );
  TRACE3("SYNC %d lock=%d\n", ((winFile*)id)->h, ((winFile*)id)->locktype);
  if( FlushFileBuffers(((winFile*)id)->h) ){
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR;
  }
}

/*
................................................................................

/*
** Truncate an open file to a specified size
*/
static int winTruncate(OsFile *id, i64 nByte){
  LONG upperBits = nByte>>32;
  assert( id!=0 );
  TRACE3("TRUNCATE %d %lld\n", ((winFile*)id)->h, nByte);
  SimulateIOError(SQLITE_IOERR);
  SetFilePointer(((winFile*)id)->h, nByte, &upperBits, FILE_BEGIN);
  SetEndOfFile(((winFile*)id)->h);
  return SQLITE_OK;
}

/*
** Determine the current size of a file in bytes
*/
static int winFileSize(OsFile *id, i64 *pSize){
  DWORD upperBits, lowerBits;
  assert( id!=0 );
  SimulateIOError(SQLITE_IOERR);
  lowerBits = GetFileSize(((winFile*)id)->h, &upperBits);
  *pSize = (((i64)upperBits)<<32) + lowerBits;
  return SQLITE_OK;
}

/*
** Acquire a reader lock.
** Different API routines are called depending on whether or not this
** is Win95 or WinNT.
*/
static int getReadLock(winFile *id){
  int res;
  if( isNT() ){
    OVERLAPPED ovlp;
    ovlp.Offset = SHARED_FIRST;
    ovlp.OffsetHigh = 0;
    ovlp.hEvent = 0;
    res = LockFileEx(id->h, LOCKFILE_FAIL_IMMEDIATELY, 0, SHARED_SIZE,0,&ovlp);
................................................................................
  }
  return res;
}

/*
** Undo a readlock
*/
static int unlockReadLock(winFile *pFile){
  int res;
  if( isNT() ){
    res = UnlockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
  }else{
    res = UnlockFile(pFile->h, SHARED_FIRST + pFile->sharedLockByte, 0, 1, 0);
  }
  return res;
}

#ifndef SQLITE_OMIT_PAGER_PRAGMAS
/*
** Check that a given pathname is a directory and is writable 
................................................................................
** must go straight to locking level 0.
*/
static int winLock(OsFile *id, int locktype){
  int rc = SQLITE_OK;    /* Return code from subroutines */
  int res = 1;           /* Result of a windows lock call */
  int newLocktype;       /* Set id->locktype to this value before exiting */
  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
  winFile *pFile = (winFile*)id;

  assert( pFile!=0 );
  TRACE5("LOCK %d %d was %d(%d)\n",

          pFile->h, locktype, pFile->locktype, pFile->sharedLockByte);

  /* If there is already a lock of this type or more restrictive on the
  ** OsFile, do nothing. Don't use the end_lock: exit path, as
  ** sqlite3OsEnterMutex() hasn't been called yet.
  */
  if( pFile->locktype>=locktype ){
    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct
  */
  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );
  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );

  /* Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or
  ** a SHARED lock.  If we are acquiring a SHARED lock, the acquisition of
  ** the PENDING_LOCK byte is temporary.
  */
  newLocktype = pFile->locktype;
  if( pFile->locktype==NO_LOCK
   || (locktype==EXCLUSIVE_LOCK && pFile->locktype==RESERVED_LOCK)
  ){
    int cnt = 3;
    while( cnt-->0 && (res = LockFile(pFile->h, PENDING_BYTE, 0, 1, 0))==0 ){
      /* Try 3 times to get the pending lock.  The pending lock might be
      ** held by another reader process who will release it momentarily.
      */
      TRACE2("could not get a PENDING lock. cnt=%d\n", cnt);
      Sleep(1);
    }
    gotPendingLock = res;
  }

  /* Acquire a shared lock
  */
  if( locktype==SHARED_LOCK && res ){
    assert( pFile->locktype==NO_LOCK );
    res = getReadLock(pFile);
    if( res ){
      newLocktype = SHARED_LOCK;
    }
  }

  /* Acquire a RESERVED lock
  */
  if( locktype==RESERVED_LOCK && res ){
    assert( pFile->locktype==SHARED_LOCK );
    res = LockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
    if( res ){
      newLocktype = RESERVED_LOCK;
    }
  }

  /* Acquire a PENDING lock
  */
................................................................................
    newLocktype = PENDING_LOCK;
    gotPendingLock = 0;
  }

  /* Acquire an EXCLUSIVE lock
  */
  if( locktype==EXCLUSIVE_LOCK && res ){
    assert( pFile->locktype>=SHARED_LOCK );
    res = unlockReadLock(pFile);
    TRACE2("unreadlock = %d\n", res);
    res = LockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
    if( res ){
      newLocktype = EXCLUSIVE_LOCK;
    }else{
      TRACE2("error-code = %d\n", GetLastError());
    }
  }

  /* If we are holding a PENDING lock that ought to be released, then
  ** release it now.
  */
  if( gotPendingLock && locktype==SHARED_LOCK ){
    UnlockFile(pFile->h, PENDING_BYTE, 0, 1, 0);
  }

  /* Update the state of the lock has held in the file descriptor then
  ** return the appropriate result code.
  */
  if( res ){
    rc = SQLITE_OK;
  }else{
    TRACE4("LOCK FAILED %d trying for %d but got %d\n", pFile->h,
           locktype, newLocktype);
    rc = SQLITE_BUSY;
  }
  pFile->locktype = newLocktype;
  return rc;
}

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero, otherwise zero.
*/
static int winCheckReservedLock(OsFile *id){
  int rc;
  winFile *pFile = (winFile*)id;
  assert( pFile!=0 );
  if( pFile->locktype>=RESERVED_LOCK ){
    rc = 1;
    TRACE3("TEST WR-LOCK %d %d (local)\n", pFile->h, rc);
  }else{
    rc = LockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
    if( rc ){
      UnlockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
    }
    rc = !rc;
    TRACE3("TEST WR-LOCK %d %d (remote)\n", pFile->h, rc);
  }
  return rc;
}

/*
** Lower the locking level on file descriptor id to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
................................................................................
** It is not possible for this routine to fail if the second argument
** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
** might return SQLITE_IOERR;
*/
static int winUnlock(OsFile *id, int locktype){
  int type;
  int rc = SQLITE_OK;
  winFile *pFile = (winFile*)id;
  assert( pFile!=0 );
  assert( locktype<=SHARED_LOCK );
  TRACE5("UNLOCK %d to %d was %d(%d)\n", pFile->h, locktype,
          pFile->locktype, pFile->sharedLockByte);
  type = pFile->locktype;
  if( type>=EXCLUSIVE_LOCK ){
    UnlockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
    if( locktype==SHARED_LOCK && !getReadLock(pFile) ){
      /* This should never happen.  We should always be able to
      ** reacquire the read lock */
      rc = SQLITE_IOERR;
    }
  }
  if( type>=RESERVED_LOCK ){
    UnlockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
  }
  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
    unlockReadLock(pFile);
  }
  if( type>=PENDING_LOCK ){
    UnlockFile(pFile->h, PENDING_BYTE, 0, 1, 0);
  }
  pFile->locktype = locktype;
  return rc;
}

/*
** Turn a relative pathname into a full pathname.  Return a pointer
** to the full pathname stored in space obtained from sqliteMalloc().
** The calling function is responsible for freeing this space once it
................................................................................
  return;
}

/*
** Return the underlying file handle for an OsFile
*/
static int winFileHandle(OsFile *id){
  return (int)((winFile*)id)->h;
}

/*
** Return an integer that indices the type of lock currently held
** by this handle.  (Used for testing and analysis only.)
*/
static int winLockState(OsFile *id){
  return ((winFile*)id)->locktype;
}


/*
** This vector defines all the methods that can operate on an OsFile
** for win32.
*/
static const IoMethod sqlite3WinIoMethod = {
  winClose,




  winOpenDirectory,




  winRead,
  winWrite,
  winSeek,

  winTruncate,
  winSync,
  winSetFullSync,
  winFileHandle,
  winFileSize,

  winLock,
  winUnlock,



  winLockState,
  winCheckReservedLock,
};

/*
** Allocate memory for an OsFile.  Initialize the new OsFile
** to the value given in pInit and return a pointer to the new
** OsFile.  If we run out of memory, close the file and return NULL.
*/
int allocateWinFile(winFile *pInit, OsFile **pId){
  winFile *pNew;
  pNew = sqliteMalloc( sizeof(*pNew) );
  if( pNew==0 ){
    CloseHandle(pInit->h);
    *pId = 0;
    return SQLITE_NOMEM;
  }else{
    *pNew = *pInit;
    pNew->pMethod = &sqlite3WinIoMethod;
    *pId = pNew;
    return SQLITE_OK;
  }
}


#endif /* SQLITE_OMIT_DISKIO */
/***************************************************************************
** Everything above deals with file I/O.  Everything that follows deals
** with other miscellanous aspects of the operating system interface
****************************************************************************/

/*
** Get information to seed the random number generator.  The seed
** is written into the buffer zBuf[256].  The calling function must
** supply a sufficiently large buffer.
*/
static int winRandomSeed(char *zBuf){
  /* We have to initialize zBuf to prevent valgrind from reporting
  ** errors.  The reports issued by valgrind are incorrect - we would
  ** prefer that the randomness be increased by making use of the
  ** uninitialized space in zBuf - but valgrind errors tend to worry
  ** some users.  Rather than argue, it seems easier just to initialize
  ** the whole array and silence valgrind, even if that means less randomness
  ** in the random seed.
................................................................................
  GetSystemTime((LPSYSTEMTIME)zBuf);
  return SQLITE_OK;
}

/*
** Sleep for a little while.  Return the amount of time slept.
*/
static int winSleep(int ms){
  Sleep(ms);
  return ms;
}

/*
** Static variables used for thread synchronization
*/
................................................................................
** The following pair of routine implement mutual exclusion for
** multi-threaded processes.  Only a single thread is allowed to
** executed code that is surrounded by EnterMutex() and LeaveMutex().
**
** SQLite uses only a single Mutex.  There is not much critical
** code and what little there is executes quickly and without blocking.
*/
static void winEnterMutex(){
#ifdef SQLITE_W32_THREADS
  static int isInit = 0;
  while( !isInit ){
    static long lock = 0;
    if( InterlockedIncrement(&lock)==1 ){
      InitializeCriticalSection(&cs);
      isInit = 1;
................................................................................
    }
  }
  EnterCriticalSection(&cs);
#endif
  assert( !inMutex );
  inMutex = 1;
}
static void winLeaveMutex(){
  assert( inMutex );
  inMutex = 0;
#ifdef SQLITE_W32_THREADS
  LeaveCriticalSection(&cs);
#endif
}

................................................................................
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
static int winCurrentTime(double *prNow){
  FILETIME ft;
  /* FILETIME structure is a 64-bit value representing the number of 
     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5). 
  */
  double now;
  GetSystemTimeAsFileTime( &ft );
  now = ((double)ft.dwHighDateTime) * 4294967296.0; 
................................................................................
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  return 0;
}

/* Macro used to comment out routines that do not exists when there is
** no disk I/O
*/
#ifdef SQLITE_OMIT_DISKIO
# define IF_DISKIO(X)  0
#else
# define IF_DISKIO(X)  X
#endif

/*
** This is the structure that defines all of the I/O routines.
*/
struct sqlite3OsVtbl sqlite3Os = {
  IF_DISKIO( winOpenReadWrite ),
  IF_DISKIO( winOpenExclusive ),
  IF_DISKIO( winOpenReadOnly ),
  IF_DISKIO( winDelete ),
  IF_DISKIO( winFileExists ),
  IF_DISKIO( winFullPathname ),
  IF_DISKIO( winIsDirWritable ),
  IF_DISKIO( winSyncDirectory ),
  IF_DISKIO( winTempFileName ),
  winRandomSeed,
  winSleep,
  winCurrentTime,
  winEnterMutex,
  winLeaveMutex,
};

#endif /* OS_WIN */

Changes to src/pager.c.

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** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.221 2005/11/29 03:13:22 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
** to print out file-descriptors. 
**
** PAGERID() takes a pointer to a Pager struct as it's argument. The
** associated file-descriptor is returned. FILEHANDLEID() takes an OsFile
** struct as it's argument.
*/
#define PAGERID(p) FILEHANDLEID(&(p)->fd)
#define FILEHANDLEID(fd) (sqlite3Io.xFileHandle(&fd))

/*
** The page cache as a whole is always in one of the following
** states:
**
**   PAGER_UNLOCK        The page cache is not currently reading or 
**                       writing the database file.  There is no
................................................................................
** error code is something goes wrong.
**
** All values are stored on disk as big-endian.
*/
static int read32bits(OsFile *fd, u32 *pRes){
  u32 res;
  int rc;
  rc = sqlite3Io.xRead(fd, &res, sizeof(res));
  if( rc==SQLITE_OK ){
    unsigned char ac[4];
    memcpy(ac, &res, 4);
    res = (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3];
  }
  *pRes = res;
  return rc;
................................................................................
*/
static int write32bits(OsFile *fd, u32 val){
  unsigned char ac[4];
  ac[0] = (val>>24) & 0xff;
  ac[1] = (val>>16) & 0xff;
  ac[2] = (val>>8) & 0xff;
  ac[3] = val & 0xff;
  return sqlite3Io.xWrite(fd, ac, 4);
}

/*
** Write the 32-bit integer 'val' into the page identified by page header
** 'p' at offset 'offset'.
*/
static void store32bits(u32 val, PgHdr *p, int offset){
................................................................................
  i64 szJ;
  u32 cksum;
  int i;
  unsigned char aMagic[8]; /* A buffer to hold the magic header */

  *pzMaster = 0;

  rc = sqlite3Io.xFileSize(pJrnl, &szJ);
  if( rc!=SQLITE_OK || szJ<16 ) return rc;

  rc = sqlite3Io.xSeek(pJrnl, szJ-16);
  if( rc!=SQLITE_OK ) return rc;
 
  rc = read32bits(pJrnl, &len);
  if( rc!=SQLITE_OK ) return rc;

  rc = read32bits(pJrnl, &cksum);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3Io.xRead(pJrnl, aMagic, 8);
  if( rc!=SQLITE_OK || memcmp(aMagic, aJournalMagic, 8) ) return rc;

  rc = sqlite3Io.xSeek(pJrnl, szJ-16-len);
  if( rc!=SQLITE_OK ) return rc;

  *pzMaster = (char *)sqliteMalloc(len+1);
  if( !*pzMaster ){
    return SQLITE_NOMEM;
  }
  rc = sqlite3Io.xRead(pJrnl, *pzMaster, len);
  if( rc!=SQLITE_OK ){
    sqliteFree(*pzMaster);
    *pzMaster = 0;
    return rc;
  }

  /* See if the checksum matches the master journal name */
................................................................................
  if( c ){
    offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
  }
  assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
  assert( offset>=c );
  assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
  pPager->journalOff = offset;
  return sqlite3Io.xSeek(pPager->jfd, pPager->journalOff);
}

/*
** The journal file must be open when this routine is called. A journal
** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
** current location.
**
................................................................................
  **
  ** Possibly for a pager not in no-sync mode, the journal magic should not
  ** be written until nRec is filled in as part of next syncJournal(). 
  **
  ** Actually maybe the whole journal header should be delayed until that
  ** point. Think about this.
  */
  rc = sqlite3Io.xWrite(pPager->jfd, aJournalMagic, sizeof(aJournalMagic));

  if( rc==SQLITE_OK ){
    /* The nRec Field. 0xFFFFFFFF for no-sync journals. */
    rc = write32bits(pPager->jfd, pPager->noSync ? 0xffffffff : 0);
  }
  if( rc==SQLITE_OK ){
    /* The random check-hash initialiser */ 
................................................................................
    rc = write32bits(pPager->jfd, pPager->sectorSize);
  }

  /* The journal header has been written successfully. Seek the journal
  ** file descriptor to the end of the journal header sector.
  */
  if( rc==SQLITE_OK ){
    rc = sqlite3Io.xSeek(pPager->jfd, pPager->journalOff-1);
    if( rc==SQLITE_OK ){
      rc = sqlite3Io.xWrite(pPager->jfd, "\000", 1);
    }
  }
  return rc;
}

/*
** The journal file must be open when this is called. A journal header file
................................................................................
  rc = seekJournalHdr(pPager);
  if( rc ) return rc;

  if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
    return SQLITE_DONE;
  }

  rc = sqlite3Io.xRead(pPager->jfd, aMagic, sizeof(aMagic));
  if( rc ) return rc;

  if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
    return SQLITE_DONE;
  }

  rc = read32bits(pPager->jfd, pNRec);
................................................................................
  ** is being called from within pager_playback(). The local value
  ** of Pager.sectorSize is restored at the end of that routine.
  */
  rc = read32bits(pPager->jfd, (u32 *)&pPager->sectorSize);
  if( rc ) return rc;

  pPager->journalOff += JOURNAL_HDR_SZ(pPager);
  rc = sqlite3Io.xSeek(pPager->jfd, pPager->journalOff);
  return rc;
}


/*
** Write the supplied master journal name into the journal file for pager
** pPager at the current location. The master journal name must be the last
................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }
  pPager->journalOff += (len+20);

  rc = write32bits(pPager->jfd, PAGER_MJ_PGNO(pPager));
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3Io.xWrite(pPager->jfd, zMaster, len);
  if( rc!=SQLITE_OK ) return rc;

  rc = write32bits(pPager->jfd, len);
  if( rc!=SQLITE_OK ) return rc;

  rc = write32bits(pPager->jfd, cksum);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3Io.xWrite(pPager->jfd, aJournalMagic, sizeof(aJournalMagic));
  pPager->needSync = !pPager->noSync;
  return rc;
}

/*
** Add or remove a page from the list of all pages that are in the
** statement journal.
................................................................................
  pPager->pLast = 0;
  pPager->pAll = 0;
  memset(pPager->aHash, 0, sizeof(pPager->aHash));
  pPager->nPage = 0;
  if( pPager->state>=PAGER_RESERVED ){
    sqlite3pager_rollback(pPager);
  }
  sqlite3Io.xUnlock(pPager->fd, NO_LOCK);
  pPager->state = PAGER_UNLOCK;
  pPager->dbSize = -1;
  pPager->nRef = 0;
  assert( pPager->journalOpen==0 );
}

/*
................................................................................
  int rc;
  assert( !MEMDB );
  if( pPager->state<PAGER_RESERVED ){
    return SQLITE_OK;
  }
  sqlite3pager_stmt_commit(pPager);
  if( pPager->stmtOpen ){
    sqlite3Io.xClose(&pPager->stfd);
    pPager->stmtOpen = 0;
  }
  if( pPager->journalOpen ){
    sqlite3Io.xClose(&pPager->jfd);
    pPager->journalOpen = 0;
    sqlite3Io.xDelete(pPager->zJournal);
    sqliteFree( pPager->aInJournal );
    pPager->aInJournal = 0;
    for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
      pPg->inJournal = 0;
      pPg->dirty = 0;
      pPg->needSync = 0;
#ifdef SQLITE_CHECK_PAGES
................................................................................
    }
    pPager->dirtyCache = 0;
    pPager->nRec = 0;
  }else{
    assert( pPager->aInJournal==0 );
    assert( pPager->dirtyCache==0 || pPager->useJournal==0 );
  }
  rc = sqlite3Io.xUnlock(pPager->fd, SHARED_LOCK);
  pPager->state = PAGER_SHARED;
  pPager->origDbSize = 0;
  pPager->setMaster = 0;
  return rc;
}

/*
................................................................................
  ** statement journals.  Verify that this is always the case
  */
  assert( jfd == (useCksum ? pPager->jfd : pPager->stfd) );


  rc = read32bits(jfd, &pgno);
  if( rc!=SQLITE_OK ) return rc;
  rc = sqlite3Io.xRead(jfd, &aData, pPager->pageSize);
  if( rc!=SQLITE_OK ) return rc;
  pPager->journalOff += pPager->pageSize + 4;

  /* Sanity checking on the page.  This is more important that I originally
  ** thought.  If a power failure occurs while the journal is being written,
  ** it could cause invalid data to be written into the journal.  We need to
  ** detect this invalid data (with high probability) and ignore it.
................................................................................
  ** page content is in the main journal either because the page is not in
  ** cache or else it is marked as needSync==0.
  */
  pPg = pager_lookup(pPager, pgno);
  assert( pPager->state>=PAGER_EXCLUSIVE || pPg!=0 );
  TRACE3("PLAYBACK %d page %d\n", PAGERID(pPager), pgno);
  if( pPager->state>=PAGER_EXCLUSIVE && (pPg==0 || pPg->needSync==0) ){
    rc = sqlite3Io.xSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
    if( rc==SQLITE_OK ){
      rc = sqlite3Io.xWrite(pPager->fd, aData, pPager->pageSize);
    }
    if( pPg ) pPg->dirty = 0;
  }
  if( pPg ){
    /* No page should ever be explicitly rolled back that is in use, except
    ** for page 1 which is held in use in order to keep the lock on the
    ** database active. However such a page may be rolled back as a result
................................................................................
  OsFile *master = 0;
  char *zMasterJournal = 0; /* Contents of master journal file */
  i64 nMasterJournal;       /* Size of master journal file */

  /* Open the master journal file exclusively in case some other process
  ** is running this routine also. Not that it makes too much difference.
  */
  rc = sqlite3Io.xOpenReadOnly(zMaster, &master);
  if( rc!=SQLITE_OK ) goto delmaster_out;
  master_open = 1;
  rc = sqlite3Io.xFileSize(master, &nMasterJournal);
  if( rc!=SQLITE_OK ) goto delmaster_out;

  if( nMasterJournal>0 ){
    char *zJournal;
    char *zMasterPtr = 0;

    /* Load the entire master journal file into space obtained from
................................................................................
    ** sqliteMalloc() and pointed to by zMasterJournal. 
    */
    zMasterJournal = (char *)sqliteMalloc(nMasterJournal);
    if( !zMasterJournal ){
      rc = SQLITE_NOMEM;
      goto delmaster_out;
    }
    rc = sqlite3Io.xRead(master, zMasterJournal, nMasterJournal);
    if( rc!=SQLITE_OK ) goto delmaster_out;

    zJournal = zMasterJournal;
    while( (zJournal-zMasterJournal)<nMasterJournal ){
      if( sqlite3Io.xFileExists(zJournal) ){
        /* One of the journals pointed to by the master journal exists.
        ** Open it and check if it points at the master journal. If
        ** so, return without deleting the master journal file.
        */
        OsFile *journal = 0;
        int c;

        rc = sqlite3Io.xOpenReadOnly(zJournal, &journal);
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }

        rc = readMasterJournal(journal, &zMasterPtr);
        sqlite3Io.xClose(&journal);
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }

        c = zMasterPtr!=0 && strcmp(zMasterPtr, zMaster)==0;
        sqliteFree(zMasterPtr);
        if( c ){
................................................................................
          goto delmaster_out;
        }
      }
      zJournal += (strlen(zJournal)+1);
    }
  }
  
  sqlite3Io.xDelete(zMaster);

delmaster_out:
  if( zMasterJournal ){
    sqliteFree(zMasterJournal);
  }  
  if( master_open ){
    sqlite3Io.xClose(&master);
  }
  return rc;
}

/*
** Make every page in the cache agree with what is on disk.  In other words,
** reread the disk to reset the state of the cache.
................................................................................
static int pager_reload_cache(Pager *pPager){
  PgHdr *pPg;
  int rc = SQLITE_OK;
  for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
    char zBuf[SQLITE_MAX_PAGE_SIZE];
    if( !pPg->dirty ) continue;
    if( (int)pPg->pgno <= pPager->origDbSize ){
      rc = sqlite3Io.xSeek(pPager->fd, pPager->pageSize*(i64)(pPg->pgno-1));
      if( rc==SQLITE_OK ){
        rc = sqlite3Io.xRead(pPager->fd, zBuf, pPager->pageSize);
      }
      TRACE3("REFETCH %d page %d\n", PAGERID(pPager), pPg->pgno);
      if( rc ) break;
      CODEC(pPager, zBuf, pPg->pgno, 2);
    }else{
      memset(zBuf, 0, pPager->pageSize);
    }
................................................................................

/*
** Truncate the main file of the given pager to the number of pages
** indicated.
*/
static int pager_truncate(Pager *pPager, int nPage){
  assert( pPager->state>=PAGER_EXCLUSIVE );
  return sqlite3Io.xTruncate(pPager->fd, pPager->pageSize*(i64)nPage);
}

/*
** Playback the journal and thus restore the database file to
** the state it was in before we started making changes.  
**
** The journal file format is as follows: 
................................................................................
  int rc;                  /* Result code of a subroutine */
  char *zMaster = 0;       /* Name of master journal file if any */

  /* Figure out how many records are in the journal.  Abort early if
  ** the journal is empty.
  */
  assert( pPager->journalOpen );
  rc = sqlite3Io.xFileSize(pPager->jfd, &szJ);
  if( rc!=SQLITE_OK ){
    goto end_playback;
  }

  /* Read the master journal name from the journal, if it is present.
  ** If a master journal file name is specified, but the file is not
  ** present on disk, then the journal is not hot and does not need to be
  ** played back.
  */
  rc = readMasterJournal(pPager->jfd, &zMaster);
  assert( rc!=SQLITE_DONE );
  if( rc!=SQLITE_OK || (zMaster && !sqlite3Io.xFileExists(zMaster)) ){
    sqliteFree(zMaster);
    zMaster = 0;
    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
    goto end_playback;
  }
  sqlite3Io.xSeek(pPager->jfd, 0);
  pPager->journalOff = 0;

  /* This loop terminates either when the readJournalHdr() call returns
  ** SQLITE_DONE or an IO error occurs. */
  while( 1 ){

    /* Read the next journal header from the journal file.  If there are
................................................................................
      rc = pager_truncate(pPager, mxPg);
      if( rc!=SQLITE_OK ){
        goto end_playback;
      }
      pPager->dbSize = mxPg;
    }

    /* rc = sqlite3Io.xSeek(pPager->jfd, JOURNAL_HDR_SZ(pPager)); */
    if( rc!=SQLITE_OK ) goto end_playback;
  
    /* Copy original pages out of the journal and back into the database file.
    */
    for(i=0; i<nRec; i++){
      rc = pager_playback_one_page(pPager, pPager->jfd, 1);
      if( rc!=SQLITE_OK ){
................................................................................
  int i;                   /* Loop counter */
  int rc;

  szJ = pPager->journalOff;
#ifndef NDEBUG 
  {
    i64 os_szJ;
    rc = sqlite3Io.xFileSize(pPager->jfd, &os_szJ);
    if( rc!=SQLITE_OK ) return rc;
    assert( szJ==os_szJ );
  }
#endif

  /* Set hdrOff to be the offset to the first journal header written
  ** this statement transaction, or the end of the file if no journal
................................................................................
    rc = pager_truncate(pPager, pPager->stmtSize);
  }
  pPager->dbSize = pPager->stmtSize;

  /* Figure out how many records are in the statement journal.
  */
  assert( pPager->stmtInUse && pPager->journalOpen );
  sqlite3Io.xSeek(pPager->stfd, 0);
  nRec = pPager->stmtNRec;
  
  /* Copy original pages out of the statement journal and back into the
  ** database file.  Note that the statement journal omits checksums from
  ** each record since power-failure recovery is not important to statement
  ** journals.
  */
................................................................................
  ** was the size of the journal file when this statement was started, so
  ** everything after that needs to be rolled back, either into the
  ** database, the memory cache, or both.
  **
  ** If it is not zero, then Pager.stmtHdrOff is the offset to the start
  ** of the first journal header written during this statement transaction.
  */
  rc = sqlite3Io.xSeek(pPager->jfd, pPager->stmtJSize);
  if( rc!=SQLITE_OK ){
    goto end_stmt_playback;
  }
  pPager->journalOff = pPager->stmtJSize;
  pPager->cksumInit = pPager->stmtCksum;
  assert( JOURNAL_HDR_SZ(pPager)<(pPager->pageSize+8) );
  while( pPager->journalOff <= (hdrOff-(pPager->pageSize+8)) ){
................................................................................
}

/*
** Adjust the robustness of the database to damage due to OS crashes
** or power failures by changing the number of syncs()s when writing
** the rollback journal.  There are three levels:
**
**    OFF       sqlite3Io.xSync() is never called.  This is the default
**              for temporary and transient files.
**
**    NORMAL    The journal is synced once before writes begin on the
**              database.  This is normally adequate protection, but
**              it is theoretically possible, though very unlikely,
**              that an inopertune power failure could leave the journal
**              in a state which would cause damage to the database
................................................................................
*/
static int sqlite3pager_opentemp(char *zFile, OsFile **pFd){
  int cnt = 8;
  int rc;
  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
  do{
    cnt--;
    sqlite3Io.xTempFileName(zFile);
    rc = sqlite3Io.xOpenExclusive(zFile, pFd, 1);
  }while( cnt>0 && rc!=SQLITE_OK && rc!=SQLITE_NOMEM );
  return rc;
}

/*
** Create a new page cache and put a pointer to the page cache in *ppPager.
** The file to be cached need not exist.  The file is not locked until
................................................................................
    if( strcmp(zFilename,":memory:")==0 ){
      memDb = 1;
      zFullPathname = sqliteStrDup("");
      rc = SQLITE_OK;
    }else
#endif
    {
      zFullPathname = sqlite3Io.xFullPathname(zFilename);
      if( zFullPathname ){
        rc = sqlite3Io.xOpenReadWrite(zFullPathname, &fd, &readOnly);
      }
    }
  }else{
    rc = sqlite3pager_opentemp(zTemp, &fd);
    zFilename = zTemp;
    zFullPathname = sqlite3Io.xFullPathname(zFilename);
    if( rc==SQLITE_OK ){
      tempFile = 1;
    }
  }
  if( !zFullPathname ){
    sqlite3Io.xClose(&fd);
    return SQLITE_NOMEM;
  }
  if( rc!=SQLITE_OK ){
    sqlite3Io.xClose(&fd);
    sqliteFree(zFullPathname);
    return rc;
  }
  nameLen = strlen(zFullPathname);
  pPager = sqliteMalloc( sizeof(*pPager) + nameLen*3 + 30 );
  if( pPager==0 ){
    sqlite3Io.xClose(&fd);
    sqliteFree(zFullPathname);
    return SQLITE_NOMEM;
  }
  TRACE3("OPEN %d %s\n", FILEHANDLEID(fd), zFullPathname);
  pPager->zFilename = (char*)&pPager[1];
  pPager->zDirectory = &pPager->zFilename[nameLen+1];
  pPager->zJournal = &pPager->zDirectory[nameLen+1];
................................................................................
/*
** Read the first N bytes from the beginning of the file into memory
** that pDest points to.  No error checking is done.
*/
void sqlite3pager_read_fileheader(Pager *pPager, int N, unsigned char *pDest){
  memset(pDest, 0, N);
  if( MEMDB==0 ){
    sqlite3Io.xSeek(pPager->fd, 0);
    sqlite3Io.xRead(pPager->fd, pDest, N);
    clear_simulated_io_error();
  }
}

/*
** Return the total number of pages in the disk file associated with
** pPager. 
................................................................................
*/
int sqlite3pager_pagecount(Pager *pPager){
  i64 n;
  assert( pPager!=0 );
  if( pPager->dbSize>=0 ){
    n = pPager->dbSize;
  } else {
    if( sqlite3Io.xFileSize(pPager->fd, &n)!=SQLITE_OK ){
      pPager->errMask |= PAGER_ERR_DISK;
      return 0;
    }
    if( n>0 && n<pPager->pageSize ){
      n = 1;
    }else{
      n /= pPager->pageSize;
................................................................................
  assert( PAGER_SHARED==SHARED_LOCK );
  assert( PAGER_RESERVED==RESERVED_LOCK );
  assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );
  if( pPager->state>=locktype ){
    rc = SQLITE_OK;
  }else{
    do {
      rc = sqlite3Io.xLock(pPager->fd, locktype);
    }while( rc==SQLITE_BUSY && sqlite3InvokeBusyHandler(pPager->pBusyHandler) );
    if( rc==SQLITE_OK ){
      pPager->state = locktype;
    }
  }
  return rc;
}
................................................................................
      ** operation. So disable IO error simulation so that testing
      ** works more easily.
      */
      disable_simulated_io_errors();
      sqlite3pager_rollback(pPager);
      enable_simulated_io_errors();
      if( !MEMDB ){
        sqlite3Io.xUnlock(pPager->fd, NO_LOCK);
      }
      assert( pPager->errMask || pPager->journalOpen==0 );
      break;
    }
    case PAGER_SHARED: {
      if( !MEMDB ){
        sqlite3Io.xUnlock(pPager->fd, NO_LOCK);
      }
      break;
    }
    default: {
      /* Do nothing */
      break;
    }
................................................................................
#endif
    pNext = pPg->pNextAll;
    sqliteFree(pPg);
  }
  TRACE2("CLOSE %d\n", PAGERID(pPager));
  assert( pPager->errMask || (pPager->journalOpen==0 && pPager->stmtOpen==0) );
  if( pPager->journalOpen ){
    sqlite3Io.xClose(&pPager->jfd);
  }
  sqliteFree(pPager->aInJournal);
  if( pPager->stmtOpen ){
    sqlite3Io.xClose(&pPager->stfd);
  }
  sqlite3Io.xClose(&pPager->fd);
  /* Temp files are automatically deleted by the OS
  ** if( pPager->tempFile ){
  **   sqlite3Io.xDelete(pPager->zFilename);
  ** }
  */

  sqliteFree(pPager);
  return SQLITE_OK;
}

................................................................................
      ** was turned off after the transaction was started.  Ticket #615 */
#ifndef NDEBUG
      {
        /* Make sure the pPager->nRec counter we are keeping agrees
        ** with the nRec computed from the size of the journal file.
        */
        i64 jSz;
        rc = sqlite3Io.xFileSize(pPager->jfd, &jSz);
        if( rc!=0 ) return rc;
        assert( pPager->journalOff==jSz );
      }
#endif
      {
        /* Write the nRec value into the journal file header. If in
        ** full-synchronous mode, sync the journal first. This ensures that
        ** all data has really hit the disk before nRec is updated to mark
        ** it as a candidate for rollback. 
        */
        if( pPager->fullSync ){
          TRACE2("SYNC journal of %d\n", PAGERID(pPager));
          rc = sqlite3Io.xSync(pPager->jfd, 0);
          if( rc!=0 ) return rc;
        }
        rc = sqlite3Io.xSeek(pPager->jfd,
                           pPager->journalHdr + sizeof(aJournalMagic));
        if( rc ) return rc;
        rc = write32bits(pPager->jfd, pPager->nRec);
        if( rc ) return rc;

        rc = sqlite3Io.xSeek(pPager->jfd, pPager->journalOff);
        if( rc ) return rc;
      }
      TRACE2("SYNC journal of %d\n", PAGERID(pPager));
      rc = sqlite3Io.xSync(pPager->jfd, pPager->fullSync);
      if( rc!=0 ) return rc;
      pPager->journalStarted = 1;
    }
    pPager->needSync = 0;

    /* Erase the needSync flag from every page.
    */
................................................................................
  int rc;

  if( pList==0 ) return SQLITE_OK;
  pPager = pList->pPager;

  /* At this point there may be either a RESERVED or EXCLUSIVE lock on the
  ** database file. If there is already an EXCLUSIVE lock, the following
  ** calls to sqlite3Io.xLock() are no-ops.
  **
  ** Moving the lock from RESERVED to EXCLUSIVE actually involves going
  ** through an intermediate state PENDING.   A PENDING lock prevents new
  ** readers from attaching to the database but is unsufficient for us to
  ** write.  The idea of a PENDING lock is to prevent new readers from
  ** coming in while we wait for existing readers to clear.
  **
................................................................................
  rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
  if( rc!=SQLITE_OK ){
    return rc;
  }

  while( pList ){
    assert( pList->dirty );
    rc = sqlite3Io.xSeek(pPager->fd, (pList->pgno-1)*(i64)pPager->pageSize);
    if( rc ) return rc;
    /* If there are dirty pages in the page cache with page numbers greater
    ** than Pager.dbSize, this means sqlite3pager_truncate() was called to
    ** make the file smaller (presumably by auto-vacuum code). Do not write
    ** any such pages to the file.
    */
    if( pList->pgno<=pPager->dbSize ){
      CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6);
      TRACE3("STORE %d page %d\n", PAGERID(pPager), pList->pgno);
      rc = sqlite3Io.xWrite(pPager->fd, PGHDR_TO_DATA(pList),
                             pPager->pageSize);
      CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 0);
      TEST_INCR(pPager->nWrite);
    }
#ifndef NDEBUG
    else{
      TRACE3("NOSTORE %d page %d\n", PAGERID(pPager), pList->pgno);
................................................................................
**
** If the current size of the database file is 0 but a journal file
** exists, that is probably an old journal left over from a prior
** database with the same name.  Just delete the journal.
*/
static int hasHotJournal(Pager *pPager){
  if( !pPager->useJournal ) return 0;
  if( !sqlite3Io.xFileExists(pPager->zJournal) ) return 0;
  if( sqlite3Io.xCheckReservedLock(pPager->fd) ) return 0;
  if( sqlite3pager_pagecount(pPager)==0 ){
    sqlite3Io.xDelete(pPager->zJournal);
    return 0;
  }else{
    return 1;
  }
}

/*
................................................................................
       ** database is safe to read while this process is still rolling it 
       ** back.
       ** 
       ** Because the intermediate RESERVED lock is not requested, the
       ** second process will get to this point in the code and fail to
       ** obtain it's own EXCLUSIVE lock on the database file.
       */
       rc = sqlite3Io.xLock(pPager->fd, EXCLUSIVE_LOCK);
       if( rc!=SQLITE_OK ){
         sqlite3Io.xUnlock(pPager->fd, NO_LOCK);
         pPager->state = PAGER_UNLOCK;
         return rc;
       }
       pPager->state = PAGER_EXCLUSIVE;

       /* Open the journal for reading only.  Return SQLITE_BUSY if
       ** we are unable to open the journal file. 
       **
       ** The journal file does not need to be locked itself.  The
       ** journal file is never open unless the main database file holds
       ** a write lock, so there is never any chance of two or more
       ** processes opening the journal at the same time.
       */
       rc = sqlite3Io.xOpenReadOnly(pPager->zJournal, &pPager->jfd);
       if( rc!=SQLITE_OK ){
         sqlite3Io.xUnlock(pPager->fd, NO_LOCK);
         pPager->state = PAGER_UNLOCK;
         return SQLITE_BUSY;
       }
       pPager->journalOpen = 1;
       pPager->journalStarted = 0;
       pPager->journalOff = 0;
       pPager->setMaster = 0;
................................................................................
      return rc;
    }
    if( sqlite3pager_pagecount(pPager)<(int)pgno ){
      memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
    }else{
      int rc;
      assert( MEMDB==0 );
      rc = sqlite3Io.xSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
      if( rc==SQLITE_OK ){
        rc = sqlite3Io.xRead(pPager->fd, PGHDR_TO_DATA(pPg),
                              pPager->pageSize);
      }
      TRACE3("FETCH %d page %d\n", PAGERID(pPager), pPg->pgno);
      CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3);
      if( rc!=SQLITE_OK ){
        i64 fileSize;
        if( sqlite3Io.xFileSize(pPager->fd,&fileSize)!=SQLITE_OK
               || fileSize>=pgno*pPager->pageSize ){
          sqlite3pager_unref(PGHDR_TO_DATA(pPg));
          return rc;
        }else{
          clear_simulated_io_error();
          memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
        }
................................................................................
  assert( pPager->aInJournal==0 );
  sqlite3pager_pagecount(pPager);
  pPager->aInJournal = sqliteMalloc( pPager->dbSize/8 + 1 );
  if( pPager->aInJournal==0 ){
    rc = SQLITE_NOMEM;
    goto failed_to_open_journal;
  }
  rc = sqlite3Io.xOpenExclusive(pPager->zJournal, &pPager->jfd,
                                 pPager->tempFile);
  pPager->journalOff = 0;
  pPager->setMaster = 0;
  pPager->journalHdr = 0;
  if( rc!=SQLITE_OK ){
    goto failed_to_open_journal;
  }
  sqlite3Io.xSetFullSync(pPager->jfd, pPager->fullSync);
  sqlite3Io.xSetFullSync(pPager->fd, pPager->fullSync);
  sqlite3Io.xOpenDirectory(pPager->zDirectory, pPager->jfd);
  pPager->journalOpen = 1;
  pPager->journalStarted = 0;
  pPager->needSync = 0;
  pPager->alwaysRollback = 0;
  pPager->nRec = 0;
  if( pPager->errMask!=0 ){
    rc = pager_errcode(pPager);
................................................................................
    }
  }
  return rc;

failed_to_open_journal:
  sqliteFree(pPager->aInJournal);
  pPager->aInJournal = 0;
  sqlite3Io.xUnlock(pPager->fd, NO_LOCK);
  pPager->state = PAGER_UNLOCK;
  return rc;
}

/*
** Acquire a write-lock on the database.  The lock is removed when
** the any of the following happen:
................................................................................
  assert( pPager->state!=PAGER_UNLOCK );
  if( pPager->state==PAGER_SHARED ){
    assert( pPager->aInJournal==0 );
    if( MEMDB ){
      pPager->state = PAGER_EXCLUSIVE;
      pPager->origDbSize = pPager->dbSize;
    }else{
      rc = sqlite3Io.xLock(pPager->fd, RESERVED_LOCK);
      if( rc==SQLITE_OK ){
        pPager->state = PAGER_RESERVED;
        if( exFlag ){
          rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
        }
      }
      if( rc!=SQLITE_OK ){
................................................................................
          assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
          CODEC(pPager, pData, pPg->pgno, 7);
          cksum = pager_cksum(pPager, pPg->pgno, pData);
          saved = *(u32*)PGHDR_TO_EXTRA(pPg, pPager);
          store32bits(cksum, pPg, pPager->pageSize);
          szPg = pPager->pageSize+8;
          store32bits(pPg->pgno, pPg, -4);
          rc = sqlite3Io.xWrite(pPager->jfd, &((char*)pData)[-4], szPg);
          pPager->journalOff += szPg;
          TRACE4("JOURNAL %d page %d needSync=%d\n",
                  PAGERID(pPager), pPg->pgno, pPg->needSync);
          CODEC(pPager, pData, pPg->pgno, 0);
          *(u32*)PGHDR_TO_EXTRA(pPg, pPager) = saved;
          if( rc!=SQLITE_OK ){
            sqlite3pager_rollback(pPager);
................................................................................
        if( pHist->pStmt ){
          memcpy(pHist->pStmt, PGHDR_TO_DATA(pPg), pPager->pageSize);
        }
        TRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
      }else{
        store32bits(pPg->pgno, pPg, -4);
        CODEC(pPager, pData, pPg->pgno, 7);
        rc = sqlite3Io.xWrite(pPager->stfd,((char*)pData)-4,
                               pPager->pageSize+4);
        TRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
        CODEC(pPager, pData, pPg->pgno, 0);
        if( rc!=SQLITE_OK ){
          sqlite3pager_rollback(pPager);
          pPager->errMask |= PAGER_ERR_FULL;
          return rc;
................................................................................
    }
#endif
    pPager->pStmt = 0;
    pPager->state = PAGER_SHARED;
    return SQLITE_OK;
  }
  if( pPager->dirtyCache==0 ){
    /* Exit early (without doing the time-consuming sqlite3Io.xSync() calls)
    ** if there have been no changes to the database file. */
    assert( pPager->needSync==0 );
    rc = pager_unwritelock(pPager);
    pPager->dbSize = -1;
    return rc;
  }
  assert( pPager->journalOpen );
................................................................................
  if( !pPager->journalOpen ){
    pPager->stmtAutoopen = 1;
    return SQLITE_OK;
  }
  assert( pPager->journalOpen );
  pPager->aInStmt = sqliteMalloc( pPager->dbSize/8 + 1 );
  if( pPager->aInStmt==0 ){
    sqlite3Io.xLock(pPager->fd, SHARED_LOCK);
    return SQLITE_NOMEM;
  }
#ifndef NDEBUG
  rc = sqlite3Io.xFileSize(pPager->jfd, &pPager->stmtJSize);
  if( rc ) goto stmt_begin_failed;
  assert( pPager->stmtJSize == pPager->journalOff );
#endif
  pPager->stmtJSize = pPager->journalOff;
  pPager->stmtSize = pPager->dbSize;
  pPager->stmtHdrOff = 0;
  pPager->stmtCksum = pPager->cksumInit;
................................................................................
** Commit a statement.
*/
int sqlite3pager_stmt_commit(Pager *pPager){
  if( pPager->stmtInUse ){
    PgHdr *pPg, *pNext;
    TRACE2("STMT-COMMIT %d\n", PAGERID(pPager));
    if( !MEMDB ){
      sqlite3Io.xSeek(pPager->stfd, 0);
      /* sqlite3Io.xTruncate(pPager->stfd, 0); */
      sqliteFree( pPager->aInStmt );
      pPager->aInStmt = 0;
    }
    for(pPg=pPager->pStmt; pPg; pPg=pNext){
      pNext = pPg->pNextStmt;
      assert( pPg->inStmt );
      pPg->inStmt = 0;
................................................................................
    /* Write all dirty pages to the database file */
    pPg = pager_get_all_dirty_pages(pPager);
    rc = pager_write_pagelist(pPg);
    if( rc!=SQLITE_OK ) goto sync_exit;

    /* Sync the database file. */
    if( !pPager->noSync ){
      rc = sqlite3Io.xSync(pPager->fd, 0);
    }

    pPager->state = PAGER_SYNCED;
  }

sync_exit:
  return rc;
................................................................................
#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
/*
** Return the current state of the file lock for the given pager.
** The return value is one of NO_LOCK, SHARED_LOCK, RESERVED_LOCK,
** PENDING_LOCK, or EXCLUSIVE_LOCK.
*/
int sqlite3pager_lockstate(Pager *pPager){
  return sqlite3Io.xLockState(pPager->fd);
}
#endif

#ifdef SQLITE_DEBUG
/*
** Print a listing of all referenced pages and their ref count.
*/







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14
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..
49
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...
402
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404
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416
...
422
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436
...
513
514
515
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531
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549
...
586
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599
600
...
622
623
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631
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635
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...
646
647
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662
...
686
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...
712
713
714
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...
760
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768
769
770
771
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776
777
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783
...
847
848
849
850
851
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855
856
857
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860
861
...
896
897
898
899
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904
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913
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...
919
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933
...
979
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981
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986
987
988
989
990
991
992
993
....
1029
1030
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1036
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1038
1039
1040
1041
1042
1043
1044
1045
....
1078
1079
1080
1081
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....
1096
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1103
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1120
1121
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1123
1124
1125
1126
1127
1128
1129
....
1131
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1138
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1146
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1152
....
1159
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1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
....
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
....
1260
1261
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1265
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1269
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1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
....
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
....
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
....
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
....
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
....
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
....
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
....
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
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1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
....
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
....
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
....
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
....
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
....
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
....
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
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2153
2154
2155
2156
2157
2158
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2160
2161
2162
2163
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2165
2166
2167
....
2197
2198
2199
2200
2201
2202
2203
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2205
2206
2207
2208
2209
2210
2211
....
2218
2219
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2221
2222
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2227
2228
2229
2230
2231
2232
2233
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2235
2236
2237
2238
2239
2240
2241
2242
....
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
....
2355
2356
2357
2358
2359
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2363
2364
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2369
2370
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2373
2374
2375
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2377
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2383
2384
2385
2386
2387
....
2530
2531
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2539
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2541
2542
2543
2544
2545
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2548
2549
2550
2551
2552
2553
....
2661
2662
2663
2664
2665
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2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
....
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
....
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
....
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
....
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
....
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
....
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
....
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
....
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
....
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.222 2005/11/30 03:20:31 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
** to print out file-descriptors. 
**
** PAGERID() takes a pointer to a Pager struct as it's argument. The
** associated file-descriptor is returned. FILEHANDLEID() takes an OsFile
** struct as it's argument.
*/
#define PAGERID(p) FILEHANDLEID(&(p)->fd)
#define FILEHANDLEID(fd) (sqlite3OsFileHandle(&fd))

/*
** The page cache as a whole is always in one of the following
** states:
**
**   PAGER_UNLOCK        The page cache is not currently reading or 
**                       writing the database file.  There is no
................................................................................
** error code is something goes wrong.
**
** All values are stored on disk as big-endian.
*/
static int read32bits(OsFile *fd, u32 *pRes){
  u32 res;
  int rc;
  rc = sqlite3OsRead(fd, &res, sizeof(res));
  if( rc==SQLITE_OK ){
    unsigned char ac[4];
    memcpy(ac, &res, 4);
    res = (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3];
  }
  *pRes = res;
  return rc;
................................................................................
*/
static int write32bits(OsFile *fd, u32 val){
  unsigned char ac[4];
  ac[0] = (val>>24) & 0xff;
  ac[1] = (val>>16) & 0xff;
  ac[2] = (val>>8) & 0xff;
  ac[3] = val & 0xff;
  return sqlite3OsWrite(fd, ac, 4);
}

/*
** Write the 32-bit integer 'val' into the page identified by page header
** 'p' at offset 'offset'.
*/
static void store32bits(u32 val, PgHdr *p, int offset){
................................................................................
  i64 szJ;
  u32 cksum;
  int i;
  unsigned char aMagic[8]; /* A buffer to hold the magic header */

  *pzMaster = 0;

  rc = sqlite3OsFileSize(pJrnl, &szJ);
  if( rc!=SQLITE_OK || szJ<16 ) return rc;

  rc = sqlite3OsSeek(pJrnl, szJ-16);
  if( rc!=SQLITE_OK ) return rc;
 
  rc = read32bits(pJrnl, &len);
  if( rc!=SQLITE_OK ) return rc;

  rc = read32bits(pJrnl, &cksum);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3OsRead(pJrnl, aMagic, 8);
  if( rc!=SQLITE_OK || memcmp(aMagic, aJournalMagic, 8) ) return rc;

  rc = sqlite3OsSeek(pJrnl, szJ-16-len);
  if( rc!=SQLITE_OK ) return rc;

  *pzMaster = (char *)sqliteMalloc(len+1);
  if( !*pzMaster ){
    return SQLITE_NOMEM;
  }
  rc = sqlite3OsRead(pJrnl, *pzMaster, len);
  if( rc!=SQLITE_OK ){
    sqliteFree(*pzMaster);
    *pzMaster = 0;
    return rc;
  }

  /* See if the checksum matches the master journal name */
................................................................................
  if( c ){
    offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
  }
  assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
  assert( offset>=c );
  assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
  pPager->journalOff = offset;
  return sqlite3OsSeek(pPager->jfd, pPager->journalOff);
}

/*
** The journal file must be open when this routine is called. A journal
** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
** current location.
**
................................................................................
  **
  ** Possibly for a pager not in no-sync mode, the journal magic should not
  ** be written until nRec is filled in as part of next syncJournal(). 
  **
  ** Actually maybe the whole journal header should be delayed until that
  ** point. Think about this.
  */
  rc = sqlite3OsWrite(pPager->jfd, aJournalMagic, sizeof(aJournalMagic));

  if( rc==SQLITE_OK ){
    /* The nRec Field. 0xFFFFFFFF for no-sync journals. */
    rc = write32bits(pPager->jfd, pPager->noSync ? 0xffffffff : 0);
  }
  if( rc==SQLITE_OK ){
    /* The random check-hash initialiser */ 
................................................................................
    rc = write32bits(pPager->jfd, pPager->sectorSize);
  }

  /* The journal header has been written successfully. Seek the journal
  ** file descriptor to the end of the journal header sector.
  */
  if( rc==SQLITE_OK ){
    rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff-1);
    if( rc==SQLITE_OK ){
      rc = sqlite3OsWrite(pPager->jfd, "\000", 1);
    }
  }
  return rc;
}

/*
** The journal file must be open when this is called. A journal header file
................................................................................
  rc = seekJournalHdr(pPager);
  if( rc ) return rc;

  if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
    return SQLITE_DONE;
  }

  rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic));
  if( rc ) return rc;

  if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
    return SQLITE_DONE;
  }

  rc = read32bits(pPager->jfd, pNRec);
................................................................................
  ** is being called from within pager_playback(). The local value
  ** of Pager.sectorSize is restored at the end of that routine.
  */
  rc = read32bits(pPager->jfd, (u32 *)&pPager->sectorSize);
  if( rc ) return rc;

  pPager->journalOff += JOURNAL_HDR_SZ(pPager);
  rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff);
  return rc;
}


/*
** Write the supplied master journal name into the journal file for pager
** pPager at the current location. The master journal name must be the last
................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }
  pPager->journalOff += (len+20);

  rc = write32bits(pPager->jfd, PAGER_MJ_PGNO(pPager));
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3OsWrite(pPager->jfd, zMaster, len);
  if( rc!=SQLITE_OK ) return rc;

  rc = write32bits(pPager->jfd, len);
  if( rc!=SQLITE_OK ) return rc;

  rc = write32bits(pPager->jfd, cksum);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3OsWrite(pPager->jfd, aJournalMagic, sizeof(aJournalMagic));
  pPager->needSync = !pPager->noSync;
  return rc;
}

/*
** Add or remove a page from the list of all pages that are in the
** statement journal.
................................................................................
  pPager->pLast = 0;
  pPager->pAll = 0;
  memset(pPager->aHash, 0, sizeof(pPager->aHash));
  pPager->nPage = 0;
  if( pPager->state>=PAGER_RESERVED ){
    sqlite3pager_rollback(pPager);
  }
  sqlite3OsUnlock(pPager->fd, NO_LOCK);
  pPager->state = PAGER_UNLOCK;
  pPager->dbSize = -1;
  pPager->nRef = 0;
  assert( pPager->journalOpen==0 );
}

/*
................................................................................
  int rc;
  assert( !MEMDB );
  if( pPager->state<PAGER_RESERVED ){
    return SQLITE_OK;
  }
  sqlite3pager_stmt_commit(pPager);
  if( pPager->stmtOpen ){
    sqlite3OsClose(&pPager->stfd);
    pPager->stmtOpen = 0;
  }
  if( pPager->journalOpen ){
    sqlite3OsClose(&pPager->jfd);
    pPager->journalOpen = 0;
    sqlite3Os.xDelete(pPager->zJournal);
    sqliteFree( pPager->aInJournal );
    pPager->aInJournal = 0;
    for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
      pPg->inJournal = 0;
      pPg->dirty = 0;
      pPg->needSync = 0;
#ifdef SQLITE_CHECK_PAGES
................................................................................
    }
    pPager->dirtyCache = 0;
    pPager->nRec = 0;
  }else{
    assert( pPager->aInJournal==0 );
    assert( pPager->dirtyCache==0 || pPager->useJournal==0 );
  }
  rc = sqlite3OsUnlock(pPager->fd, SHARED_LOCK);
  pPager->state = PAGER_SHARED;
  pPager->origDbSize = 0;
  pPager->setMaster = 0;
  return rc;
}

/*
................................................................................
  ** statement journals.  Verify that this is always the case
  */
  assert( jfd == (useCksum ? pPager->jfd : pPager->stfd) );


  rc = read32bits(jfd, &pgno);
  if( rc!=SQLITE_OK ) return rc;
  rc = sqlite3OsRead(jfd, &aData, pPager->pageSize);
  if( rc!=SQLITE_OK ) return rc;
  pPager->journalOff += pPager->pageSize + 4;

  /* Sanity checking on the page.  This is more important that I originally
  ** thought.  If a power failure occurs while the journal is being written,
  ** it could cause invalid data to be written into the journal.  We need to
  ** detect this invalid data (with high probability) and ignore it.
................................................................................
  ** page content is in the main journal either because the page is not in
  ** cache or else it is marked as needSync==0.
  */
  pPg = pager_lookup(pPager, pgno);
  assert( pPager->state>=PAGER_EXCLUSIVE || pPg!=0 );
  TRACE3("PLAYBACK %d page %d\n", PAGERID(pPager), pgno);
  if( pPager->state>=PAGER_EXCLUSIVE && (pPg==0 || pPg->needSync==0) ){
    rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
    if( rc==SQLITE_OK ){
      rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize);
    }
    if( pPg ) pPg->dirty = 0;
  }
  if( pPg ){
    /* No page should ever be explicitly rolled back that is in use, except
    ** for page 1 which is held in use in order to keep the lock on the
    ** database active. However such a page may be rolled back as a result
................................................................................
  OsFile *master = 0;
  char *zMasterJournal = 0; /* Contents of master journal file */
  i64 nMasterJournal;       /* Size of master journal file */

  /* Open the master journal file exclusively in case some other process
  ** is running this routine also. Not that it makes too much difference.
  */
  rc = sqlite3Os.xOpenReadOnly(zMaster, &master);
  if( rc!=SQLITE_OK ) goto delmaster_out;
  master_open = 1;
  rc = sqlite3OsFileSize(master, &nMasterJournal);
  if( rc!=SQLITE_OK ) goto delmaster_out;

  if( nMasterJournal>0 ){
    char *zJournal;
    char *zMasterPtr = 0;

    /* Load the entire master journal file into space obtained from
................................................................................
    ** sqliteMalloc() and pointed to by zMasterJournal. 
    */
    zMasterJournal = (char *)sqliteMalloc(nMasterJournal);
    if( !zMasterJournal ){
      rc = SQLITE_NOMEM;
      goto delmaster_out;
    }
    rc = sqlite3OsRead(master, zMasterJournal, nMasterJournal);
    if( rc!=SQLITE_OK ) goto delmaster_out;

    zJournal = zMasterJournal;
    while( (zJournal-zMasterJournal)<nMasterJournal ){
      if( sqlite3Os.xFileExists(zJournal) ){
        /* One of the journals pointed to by the master journal exists.
        ** Open it and check if it points at the master journal. If
        ** so, return without deleting the master journal file.
        */
        OsFile *journal = 0;
        int c;

        rc = sqlite3Os.xOpenReadOnly(zJournal, &journal);
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }

        rc = readMasterJournal(journal, &zMasterPtr);
        sqlite3OsClose(&journal);
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }

        c = zMasterPtr!=0 && strcmp(zMasterPtr, zMaster)==0;
        sqliteFree(zMasterPtr);
        if( c ){
................................................................................
          goto delmaster_out;
        }
      }
      zJournal += (strlen(zJournal)+1);
    }
  }
  
  sqlite3Os.xDelete(zMaster);

delmaster_out:
  if( zMasterJournal ){
    sqliteFree(zMasterJournal);
  }  
  if( master_open ){
    sqlite3OsClose(&master);
  }
  return rc;
}

/*
** Make every page in the cache agree with what is on disk.  In other words,
** reread the disk to reset the state of the cache.
................................................................................
static int pager_reload_cache(Pager *pPager){
  PgHdr *pPg;
  int rc = SQLITE_OK;
  for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
    char zBuf[SQLITE_MAX_PAGE_SIZE];
    if( !pPg->dirty ) continue;
    if( (int)pPg->pgno <= pPager->origDbSize ){
      rc = sqlite3OsSeek(pPager->fd, pPager->pageSize*(i64)(pPg->pgno-1));
      if( rc==SQLITE_OK ){
        rc = sqlite3OsRead(pPager->fd, zBuf, pPager->pageSize);
      }
      TRACE3("REFETCH %d page %d\n", PAGERID(pPager), pPg->pgno);
      if( rc ) break;
      CODEC(pPager, zBuf, pPg->pgno, 2);
    }else{
      memset(zBuf, 0, pPager->pageSize);
    }
................................................................................

/*
** Truncate the main file of the given pager to the number of pages
** indicated.
*/
static int pager_truncate(Pager *pPager, int nPage){
  assert( pPager->state>=PAGER_EXCLUSIVE );
  return sqlite3OsTruncate(pPager->fd, pPager->pageSize*(i64)nPage);
}

/*
** Playback the journal and thus restore the database file to
** the state it was in before we started making changes.  
**
** The journal file format is as follows: 
................................................................................
  int rc;                  /* Result code of a subroutine */
  char *zMaster = 0;       /* Name of master journal file if any */

  /* Figure out how many records are in the journal.  Abort early if
  ** the journal is empty.
  */
  assert( pPager->journalOpen );
  rc = sqlite3OsFileSize(pPager->jfd, &szJ);
  if( rc!=SQLITE_OK ){
    goto end_playback;
  }

  /* Read the master journal name from the journal, if it is present.
  ** If a master journal file name is specified, but the file is not
  ** present on disk, then the journal is not hot and does not need to be
  ** played back.
  */
  rc = readMasterJournal(pPager->jfd, &zMaster);
  assert( rc!=SQLITE_DONE );
  if( rc!=SQLITE_OK || (zMaster && !sqlite3Os.xFileExists(zMaster)) ){
    sqliteFree(zMaster);
    zMaster = 0;
    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
    goto end_playback;
  }
  sqlite3OsSeek(pPager->jfd, 0);
  pPager->journalOff = 0;

  /* This loop terminates either when the readJournalHdr() call returns
  ** SQLITE_DONE or an IO error occurs. */
  while( 1 ){

    /* Read the next journal header from the journal file.  If there are
................................................................................
      rc = pager_truncate(pPager, mxPg);
      if( rc!=SQLITE_OK ){
        goto end_playback;
      }
      pPager->dbSize = mxPg;
    }

    /* rc = sqlite3OsSeek(pPager->jfd, JOURNAL_HDR_SZ(pPager)); */
    if( rc!=SQLITE_OK ) goto end_playback;
  
    /* Copy original pages out of the journal and back into the database file.
    */
    for(i=0; i<nRec; i++){
      rc = pager_playback_one_page(pPager, pPager->jfd, 1);
      if( rc!=SQLITE_OK ){
................................................................................
  int i;                   /* Loop counter */
  int rc;

  szJ = pPager->journalOff;
#ifndef NDEBUG 
  {
    i64 os_szJ;
    rc = sqlite3OsFileSize(pPager->jfd, &os_szJ);
    if( rc!=SQLITE_OK ) return rc;
    assert( szJ==os_szJ );
  }
#endif

  /* Set hdrOff to be the offset to the first journal header written
  ** this statement transaction, or the end of the file if no journal
................................................................................
    rc = pager_truncate(pPager, pPager->stmtSize);
  }
  pPager->dbSize = pPager->stmtSize;

  /* Figure out how many records are in the statement journal.
  */
  assert( pPager->stmtInUse && pPager->journalOpen );
  sqlite3OsSeek(pPager->stfd, 0);
  nRec = pPager->stmtNRec;
  
  /* Copy original pages out of the statement journal and back into the
  ** database file.  Note that the statement journal omits checksums from
  ** each record since power-failure recovery is not important to statement
  ** journals.
  */
................................................................................
  ** was the size of the journal file when this statement was started, so
  ** everything after that needs to be rolled back, either into the
  ** database, the memory cache, or both.
  **
  ** If it is not zero, then Pager.stmtHdrOff is the offset to the start
  ** of the first journal header written during this statement transaction.
  */
  rc = sqlite3OsSeek(pPager->jfd, pPager->stmtJSize);
  if( rc!=SQLITE_OK ){
    goto end_stmt_playback;
  }
  pPager->journalOff = pPager->stmtJSize;
  pPager->cksumInit = pPager->stmtCksum;
  assert( JOURNAL_HDR_SZ(pPager)<(pPager->pageSize+8) );
  while( pPager->journalOff <= (hdrOff-(pPager->pageSize+8)) ){
................................................................................
}

/*
** Adjust the robustness of the database to damage due to OS crashes
** or power failures by changing the number of syncs()s when writing
** the rollback journal.  There are three levels:
**
**    OFF       sqlite3OsSync() is never called.  This is the default
**              for temporary and transient files.
**
**    NORMAL    The journal is synced once before writes begin on the
**              database.  This is normally adequate protection, but
**              it is theoretically possible, though very unlikely,
**              that an inopertune power failure could leave the journal
**              in a state which would cause damage to the database
................................................................................
*/
static int sqlite3pager_opentemp(char *zFile, OsFile **pFd){
  int cnt = 8;
  int rc;
  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
  do{
    cnt--;
    sqlite3Os.xTempFileName(zFile);
    rc = sqlite3Os.xOpenExclusive(zFile, pFd, 1);
  }while( cnt>0 && rc!=SQLITE_OK && rc!=SQLITE_NOMEM );
  return rc;
}

/*
** Create a new page cache and put a pointer to the page cache in *ppPager.
** The file to be cached need not exist.  The file is not locked until
................................................................................
    if( strcmp(zFilename,":memory:")==0 ){
      memDb = 1;
      zFullPathname = sqliteStrDup("");
      rc = SQLITE_OK;
    }else
#endif
    {
      zFullPathname = sqlite3Os.xFullPathname(zFilename);
      if( zFullPathname ){
        rc = sqlite3Os.xOpenReadWrite(zFullPathname, &fd, &readOnly);
      }
    }
  }else{
    rc = sqlite3pager_opentemp(zTemp, &fd);
    zFilename = zTemp;
    zFullPathname = sqlite3Os.xFullPathname(zFilename);
    if( rc==SQLITE_OK ){
      tempFile = 1;
    }
  }
  if( !zFullPathname ){
    sqlite3OsClose(&fd);
    return SQLITE_NOMEM;
  }
  if( rc!=SQLITE_OK ){
    sqlite3OsClose(&fd);
    sqliteFree(zFullPathname);
    return rc;
  }
  nameLen = strlen(zFullPathname);
  pPager = sqliteMalloc( sizeof(*pPager) + nameLen*3 + 30 );
  if( pPager==0 ){
    sqlite3OsClose(&fd);
    sqliteFree(zFullPathname);
    return SQLITE_NOMEM;
  }
  TRACE3("OPEN %d %s\n", FILEHANDLEID(fd), zFullPathname);
  pPager->zFilename = (char*)&pPager[1];
  pPager->zDirectory = &pPager->zFilename[nameLen+1];
  pPager->zJournal = &pPager->zDirectory[nameLen+1];
................................................................................
/*
** Read the first N bytes from the beginning of the file into memory
** that pDest points to.  No error checking is done.
*/
void sqlite3pager_read_fileheader(Pager *pPager, int N, unsigned char *pDest){
  memset(pDest, 0, N);
  if( MEMDB==0 ){
    sqlite3OsSeek(pPager->fd, 0);
    sqlite3OsRead(pPager->fd, pDest, N);
    clear_simulated_io_error();
  }
}

/*
** Return the total number of pages in the disk file associated with
** pPager. 
................................................................................
*/
int sqlite3pager_pagecount(Pager *pPager){
  i64 n;
  assert( pPager!=0 );
  if( pPager->dbSize>=0 ){
    n = pPager->dbSize;
  } else {
    if( sqlite3OsFileSize(pPager->fd, &n)!=SQLITE_OK ){
      pPager->errMask |= PAGER_ERR_DISK;
      return 0;
    }
    if( n>0 && n<pPager->pageSize ){
      n = 1;
    }else{
      n /= pPager->pageSize;
................................................................................
  assert( PAGER_SHARED==SHARED_LOCK );
  assert( PAGER_RESERVED==RESERVED_LOCK );
  assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );
  if( pPager->state>=locktype ){
    rc = SQLITE_OK;
  }else{
    do {
      rc = sqlite3OsLock(pPager->fd, locktype);
    }while( rc==SQLITE_BUSY && sqlite3InvokeBusyHandler(pPager->pBusyHandler) );
    if( rc==SQLITE_OK ){
      pPager->state = locktype;
    }
  }
  return rc;
}
................................................................................
      ** operation. So disable IO error simulation so that testing
      ** works more easily.
      */
      disable_simulated_io_errors();
      sqlite3pager_rollback(pPager);
      enable_simulated_io_errors();
      if( !MEMDB ){
        sqlite3OsUnlock(pPager->fd, NO_LOCK);
      }
      assert( pPager->errMask || pPager->journalOpen==0 );
      break;
    }
    case PAGER_SHARED: {
      if( !MEMDB ){
        sqlite3OsUnlock(pPager->fd, NO_LOCK);
      }
      break;
    }
    default: {
      /* Do nothing */
      break;
    }
................................................................................
#endif
    pNext = pPg->pNextAll;
    sqliteFree(pPg);
  }
  TRACE2("CLOSE %d\n", PAGERID(pPager));
  assert( pPager->errMask || (pPager->journalOpen==0 && pPager->stmtOpen==0) );
  if( pPager->journalOpen ){
    sqlite3OsClose(&pPager->jfd);
  }
  sqliteFree(pPager->aInJournal);
  if( pPager->stmtOpen ){
    sqlite3OsClose(&pPager->stfd);
  }
  sqlite3OsClose(&pPager->fd);
  /* Temp files are automatically deleted by the OS
  ** if( pPager->tempFile ){
  **   sqlite3Os.xDelete(pPager->zFilename);
  ** }
  */

  sqliteFree(pPager);
  return SQLITE_OK;
}

................................................................................
      ** was turned off after the transaction was started.  Ticket #615 */
#ifndef NDEBUG
      {
        /* Make sure the pPager->nRec counter we are keeping agrees
        ** with the nRec computed from the size of the journal file.
        */
        i64 jSz;
        rc = sqlite3OsFileSize(pPager->jfd, &jSz);
        if( rc!=0 ) return rc;
        assert( pPager->journalOff==jSz );
      }
#endif
      {
        /* Write the nRec value into the journal file header. If in
        ** full-synchronous mode, sync the journal first. This ensures that
        ** all data has really hit the disk before nRec is updated to mark
        ** it as a candidate for rollback. 
        */
        if( pPager->fullSync ){
          TRACE2("SYNC journal of %d\n", PAGERID(pPager));
          rc = sqlite3OsSync(pPager->jfd, 0);
          if( rc!=0 ) return rc;
        }
        rc = sqlite3OsSeek(pPager->jfd,
                           pPager->journalHdr + sizeof(aJournalMagic));
        if( rc ) return rc;
        rc = write32bits(pPager->jfd, pPager->nRec);
        if( rc ) return rc;

        rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff);
        if( rc ) return rc;
      }
      TRACE2("SYNC journal of %d\n", PAGERID(pPager));
      rc = sqlite3OsSync(pPager->jfd, pPager->fullSync);
      if( rc!=0 ) return rc;
      pPager->journalStarted = 1;
    }
    pPager->needSync = 0;

    /* Erase the needSync flag from every page.
    */
................................................................................
  int rc;

  if( pList==0 ) return SQLITE_OK;
  pPager = pList->pPager;

  /* At this point there may be either a RESERVED or EXCLUSIVE lock on the
  ** database file. If there is already an EXCLUSIVE lock, the following
  ** calls to sqlite3OsLock() are no-ops.
  **
  ** Moving the lock from RESERVED to EXCLUSIVE actually involves going
  ** through an intermediate state PENDING.   A PENDING lock prevents new
  ** readers from attaching to the database but is unsufficient for us to
  ** write.  The idea of a PENDING lock is to prevent new readers from
  ** coming in while we wait for existing readers to clear.
  **
................................................................................
  rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
  if( rc!=SQLITE_OK ){
    return rc;
  }

  while( pList ){
    assert( pList->dirty );
    rc = sqlite3OsSeek(pPager->fd, (pList->pgno-1)*(i64)pPager->pageSize);
    if( rc ) return rc;
    /* If there are dirty pages in the page cache with page numbers greater
    ** than Pager.dbSize, this means sqlite3pager_truncate() was called to
    ** make the file smaller (presumably by auto-vacuum code). Do not write
    ** any such pages to the file.
    */
    if( pList->pgno<=pPager->dbSize ){
      CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6);
      TRACE3("STORE %d page %d\n", PAGERID(pPager), pList->pgno);
      rc = sqlite3OsWrite(pPager->fd, PGHDR_TO_DATA(pList),
                             pPager->pageSize);
      CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 0);
      TEST_INCR(pPager->nWrite);
    }
#ifndef NDEBUG
    else{
      TRACE3("NOSTORE %d page %d\n", PAGERID(pPager), pList->pgno);
................................................................................
**
** If the current size of the database file is 0 but a journal file
** exists, that is probably an old journal left over from a prior
** database with the same name.  Just delete the journal.
*/
static int hasHotJournal(Pager *pPager){
  if( !pPager->useJournal ) return 0;
  if( !sqlite3Os.xFileExists(pPager->zJournal) ) return 0;
  if( sqlite3OsCheckReservedLock(pPager->fd) ) return 0;
  if( sqlite3pager_pagecount(pPager)==0 ){
    sqlite3Os.xDelete(pPager->zJournal);
    return 0;
  }else{
    return 1;
  }
}

/*
................................................................................
       ** database is safe to read while this process is still rolling it 
       ** back.
       ** 
       ** Because the intermediate RESERVED lock is not requested, the
       ** second process will get to this point in the code and fail to
       ** obtain it's own EXCLUSIVE lock on the database file.
       */
       rc = sqlite3OsLock(pPager->fd, EXCLUSIVE_LOCK);
       if( rc!=SQLITE_OK ){
         sqlite3OsUnlock(pPager->fd, NO_LOCK);
         pPager->state = PAGER_UNLOCK;
         return rc;
       }
       pPager->state = PAGER_EXCLUSIVE;

       /* Open the journal for reading only.  Return SQLITE_BUSY if
       ** we are unable to open the journal file. 
       **
       ** The journal file does not need to be locked itself.  The
       ** journal file is never open unless the main database file holds
       ** a write lock, so there is never any chance of two or more
       ** processes opening the journal at the same time.
       */
       rc = sqlite3Os.xOpenReadOnly(pPager->zJournal, &pPager->jfd);
       if( rc!=SQLITE_OK ){
         sqlite3OsUnlock(pPager->fd, NO_LOCK);
         pPager->state = PAGER_UNLOCK;
         return SQLITE_BUSY;
       }
       pPager->journalOpen = 1;
       pPager->journalStarted = 0;
       pPager->journalOff = 0;
       pPager->setMaster = 0;
................................................................................
      return rc;
    }
    if( sqlite3pager_pagecount(pPager)<(int)pgno ){
      memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
    }else{
      int rc;
      assert( MEMDB==0 );
      rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
      if( rc==SQLITE_OK ){
        rc = sqlite3OsRead(pPager->fd, PGHDR_TO_DATA(pPg),
                              pPager->pageSize);
      }
      TRACE3("FETCH %d page %d\n", PAGERID(pPager), pPg->pgno);
      CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3);
      if( rc!=SQLITE_OK ){
        i64 fileSize;
        if( sqlite3OsFileSize(pPager->fd,&fileSize)!=SQLITE_OK
               || fileSize>=pgno*pPager->pageSize ){
          sqlite3pager_unref(PGHDR_TO_DATA(pPg));
          return rc;
        }else{
          clear_simulated_io_error();
          memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
        }
................................................................................
  assert( pPager->aInJournal==0 );
  sqlite3pager_pagecount(pPager);
  pPager->aInJournal = sqliteMalloc( pPager->dbSize/8 + 1 );
  if( pPager->aInJournal==0 ){
    rc = SQLITE_NOMEM;
    goto failed_to_open_journal;
  }
  rc = sqlite3Os.xOpenExclusive(pPager->zJournal, &pPager->jfd,
                                 pPager->tempFile);
  pPager->journalOff = 0;
  pPager->setMaster = 0;
  pPager->journalHdr = 0;
  if( rc!=SQLITE_OK ){
    goto failed_to_open_journal;
  }
  sqlite3OsSetFullSync(pPager->jfd, pPager->fullSync);
  sqlite3OsSetFullSync(pPager->fd, pPager->fullSync);
  sqlite3OsOpenDirectory(pPager->jfd, pPager->zDirectory);
  pPager->journalOpen = 1;
  pPager->journalStarted = 0;
  pPager->needSync = 0;
  pPager->alwaysRollback = 0;
  pPager->nRec = 0;
  if( pPager->errMask!=0 ){
    rc = pager_errcode(pPager);
................................................................................
    }
  }
  return rc;

failed_to_open_journal:
  sqliteFree(pPager->aInJournal);
  pPager->aInJournal = 0;
  sqlite3OsUnlock(pPager->fd, NO_LOCK);
  pPager->state = PAGER_UNLOCK;
  return rc;
}

/*
** Acquire a write-lock on the database.  The lock is removed when
** the any of the following happen:
................................................................................
  assert( pPager->state!=PAGER_UNLOCK );
  if( pPager->state==PAGER_SHARED ){
    assert( pPager->aInJournal==0 );
    if( MEMDB ){
      pPager->state = PAGER_EXCLUSIVE;
      pPager->origDbSize = pPager->dbSize;
    }else{
      rc = sqlite3OsLock(pPager->fd, RESERVED_LOCK);
      if( rc==SQLITE_OK ){
        pPager->state = PAGER_RESERVED;
        if( exFlag ){
          rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
        }
      }
      if( rc!=SQLITE_OK ){
................................................................................
          assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
          CODEC(pPager, pData, pPg->pgno, 7);
          cksum = pager_cksum(pPager, pPg->pgno, pData);
          saved = *(u32*)PGHDR_TO_EXTRA(pPg, pPager);
          store32bits(cksum, pPg, pPager->pageSize);
          szPg = pPager->pageSize+8;
          store32bits(pPg->pgno, pPg, -4);
          rc = sqlite3OsWrite(pPager->jfd, &((char*)pData)[-4], szPg);
          pPager->journalOff += szPg;
          TRACE4("JOURNAL %d page %d needSync=%d\n",
                  PAGERID(pPager), pPg->pgno, pPg->needSync);
          CODEC(pPager, pData, pPg->pgno, 0);
          *(u32*)PGHDR_TO_EXTRA(pPg, pPager) = saved;
          if( rc!=SQLITE_OK ){
            sqlite3pager_rollback(pPager);
................................................................................
        if( pHist->pStmt ){
          memcpy(pHist->pStmt, PGHDR_TO_DATA(pPg), pPager->pageSize);
        }
        TRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
      }else{
        store32bits(pPg->pgno, pPg, -4);
        CODEC(pPager, pData, pPg->pgno, 7);
        rc = sqlite3OsWrite(pPager->stfd,((char*)pData)-4,
                               pPager->pageSize+4);
        TRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
        CODEC(pPager, pData, pPg->pgno, 0);
        if( rc!=SQLITE_OK ){
          sqlite3pager_rollback(pPager);
          pPager->errMask |= PAGER_ERR_FULL;
          return rc;
................................................................................
    }
#endif
    pPager->pStmt = 0;
    pPager->state = PAGER_SHARED;
    return SQLITE_OK;
  }
  if( pPager->dirtyCache==0 ){
    /* Exit early (without doing the time-consuming sqlite3OsSync() calls)
    ** if there have been no changes to the database file. */
    assert( pPager->needSync==0 );
    rc = pager_unwritelock(pPager);
    pPager->dbSize = -1;
    return rc;
  }
  assert( pPager->journalOpen );
................................................................................
  if( !pPager->journalOpen ){
    pPager->stmtAutoopen = 1;
    return SQLITE_OK;
  }
  assert( pPager->journalOpen );
  pPager->aInStmt = sqliteMalloc( pPager->dbSize/8 + 1 );
  if( pPager->aInStmt==0 ){
    sqlite3OsLock(pPager->fd, SHARED_LOCK);
    return SQLITE_NOMEM;
  }
#ifndef NDEBUG
  rc = sqlite3OsFileSize(pPager->jfd, &pPager->stmtJSize);
  if( rc ) goto stmt_begin_failed;
  assert( pPager->stmtJSize == pPager->journalOff );
#endif
  pPager->stmtJSize = pPager->journalOff;
  pPager->stmtSize = pPager->dbSize;
  pPager->stmtHdrOff = 0;
  pPager->stmtCksum = pPager->cksumInit;
................................................................................
** Commit a statement.
*/
int sqlite3pager_stmt_commit(Pager *pPager){
  if( pPager->stmtInUse ){
    PgHdr *pPg, *pNext;
    TRACE2("STMT-COMMIT %d\n", PAGERID(pPager));
    if( !MEMDB ){
      sqlite3OsSeek(pPager->stfd, 0);
      /* sqlite3OsTruncate(pPager->stfd, 0); */
      sqliteFree( pPager->aInStmt );
      pPager->aInStmt = 0;
    }
    for(pPg=pPager->pStmt; pPg; pPg=pNext){
      pNext = pPg->pNextStmt;
      assert( pPg->inStmt );
      pPg->inStmt = 0;
................................................................................
    /* Write all dirty pages to the database file */
    pPg = pager_get_all_dirty_pages(pPager);
    rc = pager_write_pagelist(pPg);
    if( rc!=SQLITE_OK ) goto sync_exit;

    /* Sync the database file. */
    if( !pPager->noSync ){
      rc = sqlite3OsSync(pPager->fd, 0);
    }

    pPager->state = PAGER_SYNCED;
  }

sync_exit:
  return rc;
................................................................................
#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
/*
** Return the current state of the file lock for the given pager.
** The return value is one of NO_LOCK, SHARED_LOCK, RESERVED_LOCK,
** PENDING_LOCK, or EXCLUSIVE_LOCK.
*/
int sqlite3pager_lockstate(Pager *pPager){
  return sqlite3OsLockState(pPager->fd);
}
#endif

#ifdef SQLITE_DEBUG
/*
** Print a listing of all referenced pages and their ref count.
*/

Changes to src/pragma.c.

7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
...
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.104 2005/11/26 00:25:03 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/
................................................................................
      if( sqlite3_temp_directory ){
        sqlite3VdbeSetNumCols(v, 1);
        sqlite3VdbeSetColName(v, 0, "temp_store_directory", P3_STATIC);
        sqlite3VdbeOp3(v, OP_String8, 0, 0, sqlite3_temp_directory, 0);
        sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
      }
    }else{
      if( zRight[0] && !sqlite3Io.xIsDirWritable(zRight) ){
        sqlite3ErrorMsg(pParse, "not a writable directory");
        goto pragma_out;
      }
      if( TEMP_STORE==0
       || (TEMP_STORE==1 && db->temp_store<=1)
       || (TEMP_STORE==2 && db->temp_store==1)
      ){







|







 







|







7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
...
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.105 2005/11/30 03:20:31 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/
................................................................................
      if( sqlite3_temp_directory ){
        sqlite3VdbeSetNumCols(v, 1);
        sqlite3VdbeSetColName(v, 0, "temp_store_directory", P3_STATIC);
        sqlite3VdbeOp3(v, OP_String8, 0, 0, sqlite3_temp_directory, 0);
        sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
      }
    }else{
      if( zRight[0] && !sqlite3Os.xIsDirWritable(zRight) ){
        sqlite3ErrorMsg(pParse, "not a writable directory");
        goto pragma_out;
      }
      if( TEMP_STORE==0
       || (TEMP_STORE==1 && db->temp_store<=1)
       || (TEMP_STORE==2 && db->temp_store==1)
      ){

Changes to src/random.c.

11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
..
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
..
88
89
90
91
92
93
94
95
96
97
98
99
100
*************************************************************************
** This file contains code to implement a pseudo-random number
** generator (PRNG) for SQLite.
**
** Random numbers are used by some of the database backends in order
** to generate random integer keys for tables or random filenames.
**
** $Id: random.c,v 1.13 2005/06/12 21:35:52 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"


/*
** Get a single 8-bit random value from the RC4 PRNG.  The Mutex
................................................................................
  ** number generator) not as an encryption device.
  */
  if( !prng.isInit ){
    int i;
    char k[256];
    prng.j = 0;
    prng.i = 0;
    sqlite3OsRandomSeed(k);
    for(i=0; i<256; i++){
      prng.s[i] = i;
    }
    for(i=0; i<256; i++){
      prng.j += prng.s[i] + k[i];
      t = prng.s[prng.j];
      prng.s[prng.j] = prng.s[i];
................................................................................
}

/*
** Return N random bytes.
*/
void sqlite3Randomness(int N, void *pBuf){
  unsigned char *zBuf = pBuf;
  sqlite3OsEnterMutex();
  while( N-- ){
    *(zBuf++) = randomByte();
  }
  sqlite3OsLeaveMutex();
}







|







 







|







 







|



|

11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
..
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
..
88
89
90
91
92
93
94
95
96
97
98
99
100
*************************************************************************
** This file contains code to implement a pseudo-random number
** generator (PRNG) for SQLite.
**
** Random numbers are used by some of the database backends in order
** to generate random integer keys for tables or random filenames.
**
** $Id: random.c,v 1.14 2005/11/30 03:20:32 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"


/*
** Get a single 8-bit random value from the RC4 PRNG.  The Mutex
................................................................................
  ** number generator) not as an encryption device.
  */
  if( !prng.isInit ){
    int i;
    char k[256];
    prng.j = 0;
    prng.i = 0;
    sqlite3Os.xRandomSeed(k);
    for(i=0; i<256; i++){
      prng.s[i] = i;
    }
    for(i=0; i<256; i++){
      prng.j += prng.s[i] + k[i];
      t = prng.s[prng.j];
      prng.s[prng.j] = prng.s[i];
................................................................................
}

/*
** Return N random bytes.
*/
void sqlite3Randomness(int N, void *pBuf){
  unsigned char *zBuf = pBuf;
  sqlite3Os.xEnterMutex();
  while( N-- ){
    *(zBuf++) = randomByte();
  }
  sqlite3Os.xLeaveMutex();
}

Changes to src/test1.c.

9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
....
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
....
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
....
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
....
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
....
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the printf() interface to SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.167 2005/11/29 03:13:22 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................

  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
       Tcl_GetString(objv[0]), " filename", 0);
    return TCL_ERROR;
  }

  rc = sqlite3Io.xOpenReadWrite(Tcl_GetString(objv[1]), &pFile, &dummy);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  makePointerStr(interp, zBuf, pFile);
  Tcl_SetResult(interp, zBuf, 0);
  return TCL_ERROR;
................................................................................
       Tcl_GetString(objv[0]), " filehandle", 0);
    return TCL_ERROR;
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }
  rc = sqlite3Io.xClose(&pFile);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  return TCL_OK;
}

................................................................................
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }

  if( 0==strcmp("SHARED", Tcl_GetString(objv[2])) ){
    rc = sqlite3Io.xLock(pFile, SHARED_LOCK);
  }
  else if( 0==strcmp("RESERVED", Tcl_GetString(objv[2])) ){
    rc = sqlite3Io.xLock(pFile, RESERVED_LOCK);
  }
  else if( 0==strcmp("PENDING", Tcl_GetString(objv[2])) ){
    rc = sqlite3Io.xLock(pFile, PENDING_LOCK);
  }
  else if( 0==strcmp("EXCLUSIVE", Tcl_GetString(objv[2])) ){
    rc = sqlite3Io.xLock(pFile, EXCLUSIVE_LOCK);
  }else{
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
        Tcl_GetString(objv[0]), 
        " filehandle (SHARED|RESERVED|PENDING|EXCLUSIVE)", 0);
    return TCL_ERROR;
  }

................................................................................
       Tcl_GetString(objv[0]), " filehandle", 0);
    return TCL_ERROR;
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }
  rc = sqlite3Io.xUnlock(pFile, NO_LOCK);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  return TCL_OK;
}

................................................................................
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  char zFile[SQLITE_TEMPNAME_SIZE];
  int rc;

  rc = sqlite3Io.xTempFileName(zFile);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  Tcl_AppendResult(interp, zFile, 0);
  return TCL_OK;
}







|







 







|







 







|







 







|


|


|


|







 







|







 







|







9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
....
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
....
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
....
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
....
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
....
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the printf() interface to SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.168 2005/11/30 03:20:32 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................

  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
       Tcl_GetString(objv[0]), " filename", 0);
    return TCL_ERROR;
  }

  rc = sqlite3Os.xOpenReadWrite(Tcl_GetString(objv[1]), &pFile, &dummy);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  makePointerStr(interp, zBuf, pFile);
  Tcl_SetResult(interp, zBuf, 0);
  return TCL_ERROR;
................................................................................
       Tcl_GetString(objv[0]), " filehandle", 0);
    return TCL_ERROR;
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }
  rc = sqlite3OsClose(&pFile);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  return TCL_OK;
}

................................................................................
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }

  if( 0==strcmp("SHARED", Tcl_GetString(objv[2])) ){
    rc = sqlite3OsLock(pFile, SHARED_LOCK);
  }
  else if( 0==strcmp("RESERVED", Tcl_GetString(objv[2])) ){
    rc = sqlite3OsLock(pFile, RESERVED_LOCK);
  }
  else if( 0==strcmp("PENDING", Tcl_GetString(objv[2])) ){
    rc = sqlite3OsLock(pFile, PENDING_LOCK);
  }
  else if( 0==strcmp("EXCLUSIVE", Tcl_GetString(objv[2])) ){
    rc = sqlite3OsLock(pFile, EXCLUSIVE_LOCK);
  }else{
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
        Tcl_GetString(objv[0]), 
        " filehandle (SHARED|RESERVED|PENDING|EXCLUSIVE)", 0);
    return TCL_ERROR;
  }

................................................................................
       Tcl_GetString(objv[0]), " filehandle", 0);
    return TCL_ERROR;
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }
  rc = sqlite3OsUnlock(pFile, NO_LOCK);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  return TCL_OK;
}

................................................................................
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  char zFile[SQLITE_TEMPNAME_SIZE];
  int rc;

  rc = sqlite3Os.xTempFileName(zFile);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  Tcl_AppendResult(interp, zFile, 0);
  return TCL_OK;
}

Changes to src/test2.c.

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**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the pager.c module in SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test2.c,v 1.37 2005/11/29 03:13:22 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
  int readOnly = 0;
  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " N-MEGABYTES FILE\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[1], &n) ) return TCL_ERROR;
  rc = sqlite3Io.xOpenReadWrite(argv[2], &fd, &readOnly);
  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  offset = n;
  offset *= 1024*1024;
  rc = sqlite3Io.xSeek(fd, offset);
  if( rc ){
    Tcl_AppendResult(interp, "seek failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  rc = sqlite3Io.xWrite(fd, "Hello, World!", 14);
  sqlite3Io.xClose(&fd);
  if( rc ){
    Tcl_AppendResult(interp, "write failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}
#endif







|







 







|






|




|
|







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**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the pager.c module in SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test2.c,v 1.38 2005/11/30 03:20:32 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
  int readOnly = 0;
  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " N-MEGABYTES FILE\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[1], &n) ) return TCL_ERROR;
  rc = sqlite3Os.xOpenReadWrite(argv[2], &fd, &readOnly);
  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  offset = n;
  offset *= 1024*1024;
  rc = sqlite3OsSeek(fd, offset);
  if( rc ){
    Tcl_AppendResult(interp, "seek failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  rc = sqlite3OsWrite(fd, "Hello, World!", 14);
  sqlite3OsClose(&fd);
  if( rc ){
    Tcl_AppendResult(interp, "write failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}
#endif

Changes to src/test6.c.

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*/
#if SQLITE_TEST          /* This file is used for the testing only */
#include "sqliteInt.h"
#include "os.h"
#include "tcl.h"

/*
** A copy of the original sqlite3Io structure
*/
static struct sqlite3IoVtbl origIo;

/*
** The OsFile structure for the crash-test backend.  The pBase field
** points to an OsFile structure for the native backend.
*/

struct OsFile {

  u8 **apBlk;         /* Array of blocks that have been written to. */
  int nBlk;           /* Size of apBlock. */
  i64 offset;         /* Next character to be read from the file */
  int nMaxWrite;      /* Largest offset written to. */
  char *zName;        /* File name */
  OsFile *pBase;      /* Base class */
  OsFile *pNext;      /* Next in a list of them all */
};

/*
** Size of a simulated disk block
*/
#define BLOCKSIZE 512
#define BLOCK_OFFSET(x) ((x) * BLOCKSIZE)
................................................................................
static int iCrashDelay = 0;
static char zCrashFile[500];

/*
** Set the value of the two crash parameters.
*/
static void setCrashParams(int iDelay, char const *zFile){
  sqlite3OsEnterMutex();
  assert( strlen(zFile)<sizeof(zCrashFile) );
  strcpy(zCrashFile, zFile);
  iCrashDelay = iDelay;
  sqlite3OsLeaveMutex();
}

/*
** File zPath is being sync()ed. Return non-zero if this should
** cause a crash.
*/
static int crashRequired(char const *zPath){
  int r;
  int n;
  sqlite3OsEnterMutex();
  n = strlen(zCrashFile);
  if( zCrashFile[n-1]=='*' ){
    n--;
  }else if( strlen(zPath)>n ){
    n = strlen(zPath);
  }
  r = 0;
  if( iCrashDelay>0 && strncmp(zPath, zCrashFile, n)==0 ){
    iCrashDelay--;
    if( iCrashDelay<=0 ){
      r = 1;
    }
  }
  sqlite3OsLeaveMutex();
  return r;
}

/*
** A list of all open files.
*/
static OsFile *pAllFiles = 0;

/*
** Initialise the os_test.c specific fields of pFile.
*/
static void initFile(OsFile **pId, char const *zName, OsFile *pBase){
  OsFile *pFile = *pId = sqliteMalloc(sizeof(OsFile) + strlen(zName)+1);
  pFile->nMaxWrite = 0; 
  pFile->offset = 0;
  pFile->nBlk = 0; 
  pFile->apBlk = 0; 
  pFile->zName = (char *)(&pFile[1]);
  strcpy(pFile->zName, zName);
  pFile->pBase = pBase;
  pFile->pNext = pAllFiles;
  pAllFiles = pFile;
}

/*
** Undo the work done by initFile. Delete the OsFile structure
** and unlink the structure from the pAllFiles list.
*/
static void closeFile(OsFile **pId){
  OsFile *pFile = *pId;
  if( pFile==pAllFiles ){
    pAllFiles = pFile->pNext;
  }else{
    OsFile *p;
    for(p=pAllFiles; p->pNext!=pFile; p=p->pNext ){
      assert( p );
    }
    p->pNext = pFile->pNext;
  }
  sqliteFree(*pId);
  *pId = 0;
}

/*
** Read block 'blk' off of the real disk file and into the cache of pFile.
*/
static int readBlockIntoCache(OsFile *pFile, int blk){
  if( blk>=pFile->nBlk ){
    int n = ((pFile->nBlk * 2) + 100 + blk);
    /* if( pFile->nBlk==0 ){ printf("DIRTY %s\n", pFile->zName); } */
    pFile->apBlk = (u8 **)sqliteRealloc(pFile->apBlk, n * sizeof(u8*));
    if( !pFile->apBlk ) return SQLITE_NOMEM;
    memset(&pFile->apBlk[pFile->nBlk], 0, (n - pFile->nBlk)*sizeof(u8*));
    pFile->nBlk = n;
................................................................................
    i64 filesize;
    int rc;

    u8 *p = sqliteMalloc(BLOCKSIZE);
    if( !p ) return SQLITE_NOMEM;
    pFile->apBlk[blk] = p;

    rc = origIo.xFileSize(pFile->pBase, &filesize);
    if( rc!=SQLITE_OK ) return rc;

    if( BLOCK_OFFSET(blk)<filesize ){
      int len = BLOCKSIZE;
      rc = origIo.xSeek(pFile->pBase, blk*BLOCKSIZE);
      if( BLOCK_OFFSET(blk+1)>filesize ){
        len = filesize - BLOCK_OFFSET(blk);
      }
      if( rc!=SQLITE_OK ) return rc;
      rc = origIo.xRead(pFile->pBase, p, len);
      if( rc!=SQLITE_OK ) return rc;
    }
  }

  return SQLITE_OK;
}

/*
** Write the cache of pFile to disk. If crash is non-zero, randomly
** skip blocks when writing. The cache is deleted before returning.
*/
static int writeCache2(OsFile *pFile, int crash){
  int i;
  int nMax = pFile->nMaxWrite;
  int rc = SQLITE_OK;

  for(i=0; i<pFile->nBlk; i++){
    u8 *p = pFile->apBlk[i];
    if( p ){
................................................................................
        }else{
#ifdef TRACE_WRITECACHE
printf("Writing block %d of %s\n", i, pFile->zName); 
#endif
        }
      }
      if( rc==SQLITE_OK ){
        rc = origIo.xSeek(pFile->pBase, BLOCK_OFFSET(i));
      }
      if( rc==SQLITE_OK && !skip ){
        int len = BLOCKSIZE;
        if( BLOCK_OFFSET(i+1)>nMax ){
          len = nMax-BLOCK_OFFSET(i);
        }
        if( len>0 ){
          if( trash ){
            sqlite3Randomness(len, p);
          }
          rc = origIo.xWrite(pFile->pBase, p, len);
        }
      }
      sqliteFree(p);
    }
  }
  sqliteFree(pFile->apBlk);
  pFile->nBlk = 0;
................................................................................
  pFile->nMaxWrite = 0;
  return rc;
}

/*
** Write the cache to disk.
*/
static int writeCache(OsFile *pFile){
  if( pFile->apBlk ){
    int c = crashRequired(pFile->zName);
    if( c ){
      OsFile *p;
#ifdef TRACE_WRITECACHE
      printf("\nCrash during sync of %s\n", pFile->zName);
#endif
      for(p=pAllFiles; p; p=p->pNext){
        writeCache2(p, 1);
      }
      exit(-1);
................................................................................
  return SQLITE_OK;
}

/*
** Close the file.
*/
static int crashClose(OsFile **pId){
  OsFile *pFile = *pId;
  if( pFile ){
    /* printf("CLOSE %s (%d blocks)\n", pFile->zName, pFile->nBlk); */
    writeCache(pFile);
    origIo.xClose(&pFile->pBase);
  }
  closeFile(pId);

  return SQLITE_OK;
}

static int crashSeek(OsFile *id, i64 offset){
  id->offset = offset;
  return SQLITE_OK;
}

static int crashRead(OsFile *id, void *pBuf, int amt){
  i64 offset;       /* The current offset from the start of the file */
  i64 end;          /* The byte just past the last byte read */
  int blk;            /* Block number the read starts on */
  int i;
  u8 *zCsr;
  int rc = SQLITE_OK;
  OsFile *pFile = id;

  offset = pFile->offset;
  end = offset+amt;
  blk = (offset/BLOCKSIZE);

  zCsr = (u8 *)pBuf;
  for(i=blk; i*BLOCKSIZE<end; i++){
................................................................................
      len = len - (BLOCK_OFFSET(i+1)-end);
    }

    if( i<pFile->nBlk && pFile->apBlk[i]){
      u8 *pBlk = pFile->apBlk[i];
      memcpy(zCsr, &pBlk[off], len);
    }else{
      rc = origIo.xSeek(id->pBase, BLOCK_OFFSET(i) + off);
      if( rc!=SQLITE_OK ) return rc;
      rc = origIo.xRead(id->pBase, zCsr, len);
      if( rc!=SQLITE_OK ) return rc;
    }

    zCsr += len;
  }
  assert( zCsr==&((u8 *)pBuf)[amt] );

  id->offset = end;
  return rc;
}

static int crashWrite(OsFile *id, const void *pBuf, int amt){
  i64 offset;       /* The current offset from the start of the file */
  i64 end;          /* The byte just past the last byte written */
  int blk;            /* Block number the write starts on */
  int i;
  const u8 *zCsr;
  int rc = SQLITE_OK;


  offset = id->offset;
  end = offset+amt;
  blk = (offset/BLOCKSIZE);

  zCsr = (u8 *)pBuf;
  for(i=blk; i*BLOCKSIZE<end; i++){
    u8 *pBlk;
    int off = 0;
    int len = 0;

    /* Make sure the block is in the cache */
    rc = readBlockIntoCache(id, i);
    if( rc!=SQLITE_OK ) return rc;

    /* Write into the cache */
    pBlk = id->apBlk[i];
    assert( pBlk );

    if( BLOCK_OFFSET(i) < offset ){
      off = offset-BLOCK_OFFSET(i);
    }
    len = BLOCKSIZE - off;
    if( BLOCK_OFFSET(i+1) > end ){
      len = len - (BLOCK_OFFSET(i+1)-end);
    }
    memcpy(&pBlk[off], zCsr, len);
    zCsr += len;
  }
  if( id->nMaxWrite<end ){
    id->nMaxWrite = end;
  }
  assert( zCsr==&((u8 *)pBuf)[amt] );
  id->offset = end;
  return rc;
}

/*
** Sync the file. First flush the write-cache to disk, then call the
** real sync() function.
*/
static int crashSync(OsFile *id, int dataOnly){
  int rc;
  /* printf("SYNC %s (%d blocks)\n", (*id)->zName, (*id)->nBlk); */
  rc = writeCache(id);
  /* if( rc!=SQLITE_OK ) return rc; rc = origIo.xSync(id->pBase, dataOnly); */
  return rc;
}

/*
** Truncate the file. Set the internal OsFile.nMaxWrite variable to the new
** file size to ensure that nothing in the write-cache past this point
** is written to disk.
*/
static int crashTruncate(OsFile *id, i64 nByte){

  id->nMaxWrite = nByte;
  return origIo.xTruncate(id->pBase, nByte);
}

/*
** Return the size of the file. If the cache contains a write that extended
** the file, then return this size instead of the on-disk size.
*/
static int crashFileSize(OsFile *id, i64 *pSize){
  int rc = origIo.xFileSize(id->pBase, pSize);

  if( rc==SQLITE_OK && pSize && *pSize<id->nMaxWrite ){
    *pSize = id->nMaxWrite;
  }
  return rc;
}

/*
** The three functions used to open files. All that is required is to
** initialise the os_test.c specific fields and then call the corresponding
** os_unix.c function to really open the file.
*/
static int crashOpenReadWrite(const char *zFilename, OsFile **pId,int *pRdonly){
  OsFile *pBase = 0;
  int rc = origIo.xOpenReadWrite(zFilename, &pBase, pRdonly);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}
static int crashOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  OsFile *pBase = 0;
  int rc = origIo.xOpenExclusive(zFilename, &pBase, delFlag);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}
static int crashOpenReadOnly(const char *zFilename, OsFile **pId){
  OsFile *pBase = 0;
  int rc = origIo.xOpenReadOnly(zFilename, &pBase);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}

/*
** OpenDirectory and SyncDirectory are no-ops
*/
static int crashOpenDir(const char *zName, OsFile *id){
  return SQLITE_OK;
}
static int crashSyncDir(const char *zName){
  return SQLITE_OK;
}

/*
** Locking primitives are passed through into the underlying
** file descriptor.
*/
int crashLock(OsFile *id, int lockType){
  return origIo.xLock(id->pBase, lockType);
}
int crashUnlock(OsFile *id, int lockType){
  return origIo.xUnlock(id->pBase, lockType);
}
int crashCheckReservedLock(OsFile *id){
  return origIo.xCheckReservedLock(id->pBase);
}
void crashSetFullSync(OsFile *id, int setting){
  return;  /* This is a no-op */
}
int crashLockState(OsFile *id){
  return origIo.xLockState(id->pBase);
}

/*
** Return the underlying file handle.
*/
int crashFileHandle(OsFile *id){
















  return origIo.xFileHandle(id->pBase);





}





















/*
** tclcmd:   sqlite_crashparams DELAY CRASHFILE
**
** This procedure implements a TCL command that enables crash testing
** in testfixture.  Once enabled, crash testing cannot be disabled.
*/
................................................................................
  if( Tcl_GetIntFromObj(interp, objv[1], &delay) ) return TCL_ERROR;
  zFile = Tcl_GetStringFromObj(objv[2], &nFile);
  if( nFile>=sizeof(zCrashFile)-1 ){
    Tcl_AppendResult(interp, "crash file name too big", 0);
    return TCL_ERROR;
  }
  setCrashParams(delay, zFile);

  origIo = sqlite3Io;
  /* xDelete unchanged */
  /* xFileExists unchanged */
  sqlite3Io.xOpenReadWrite = crashOpenReadWrite;
  sqlite3Io.xOpenExclusive = crashOpenExclusive;
  sqlite3Io.xOpenReadOnly = crashOpenReadOnly;
  sqlite3Io.xOpenDirectory = crashOpenDir;
  sqlite3Io.xSyncDirectory = crashSyncDir;
  /* xTempFileName unchanged */
  /* xIsDirWritable unchanged */
  sqlite3Io.xClose = crashClose;
  sqlite3Io.xRead = crashRead;
  sqlite3Io.xWrite = crashWrite;
  sqlite3Io.xSeek = crashSeek;
  sqlite3Io.xSync = crashSync;
  sqlite3Io.xTruncate = crashTruncate;
  sqlite3Io.xFileSize = crashFileSize;
  /* xFullPathname unchanged */
  sqlite3Io.xLock = crashLock;
  sqlite3Io.xUnlock = crashUnlock;
  sqlite3Io.xCheckReservedLock = crashCheckReservedLock;
  sqlite3Io.xSetFullSync = crashSetFullSync;
  sqlite3Io.xFileHandle = crashFileHandle;
  sqlite3Io.xLockState = crashLockState;

  return TCL_OK;
}

/*
** This procedure registers the TCL procedures defined in this file.
*/
int Sqlitetest6_Init(Tcl_Interp *interp){
  Tcl_CreateObjCommand(interp, "sqlite3_crashparams", crashParamsObjCmd, 0, 0);
  return TCL_OK;
}

#endif /* SQLITE_TEST */







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*/
#if SQLITE_TEST          /* This file is used for the testing only */
#include "sqliteInt.h"
#include "os.h"
#include "tcl.h"

/*
** A copy of the original sqlite3Os structure
*/
static struct sqlite3OsVtbl origOs;

/*
** crashFile is a subclass of OsFile that is taylored for the
** crash test module.
*/
typedef struct crashFile crashFile;
struct crashFile {
  IoMethod const *pMethod; /* Must be first */
  u8 **apBlk;              /* Array of blocks that have been written to. */
  int nBlk;                /* Size of apBlock. */
  i64 offset;              /* Next character to be read from the file */
  int nMaxWrite;           /* Largest offset written to. */
  char *zName;             /* File name */
  OsFile *pBase;           /* The real file */
  crashFile *pNext;        /* Next in a list of them all */
};

/*
** Size of a simulated disk block
*/
#define BLOCKSIZE 512
#define BLOCK_OFFSET(x) ((x) * BLOCKSIZE)
................................................................................
static int iCrashDelay = 0;
static char zCrashFile[500];

/*
** Set the value of the two crash parameters.
*/
static void setCrashParams(int iDelay, char const *zFile){
  sqlite3Os.xEnterMutex();
  assert( strlen(zFile)<sizeof(zCrashFile) );
  strcpy(zCrashFile, zFile);
  iCrashDelay = iDelay;
  sqlite3Os.xLeaveMutex();
}

/*
** File zPath is being sync()ed. Return non-zero if this should
** cause a crash.
*/
static int crashRequired(char const *zPath){
  int r;
  int n;
  sqlite3Os.xEnterMutex();
  n = strlen(zCrashFile);
  if( zCrashFile[n-1]=='*' ){
    n--;
  }else if( strlen(zPath)>n ){
    n = strlen(zPath);
  }
  r = 0;
  if( iCrashDelay>0 && strncmp(zPath, zCrashFile, n)==0 ){
    iCrashDelay--;
    if( iCrashDelay<=0 ){
      r = 1;
    }
  }
  sqlite3Os.xLeaveMutex();
  return r;
}

/*
** A list of all open files.
*/
static crashFile *pAllFiles = 0;

/* Forward reference */


static void initFile(OsFile **pId, char const *zName, OsFile *pBase);












/*
** Undo the work done by initFile. Delete the OsFile structure
** and unlink the structure from the pAllFiles list.
*/
static void closeFile(crashFile **pId){
  crashFile *pFile = *pId;
  if( pFile==pAllFiles ){
    pAllFiles = pFile->pNext;
  }else{
    crashFile *p;
    for(p=pAllFiles; p->pNext!=pFile; p=p->pNext ){
      assert( p );
    }
    p->pNext = pFile->pNext;
  }
  sqliteFree(*pId);
  *pId = 0;
}

/*
** Read block 'blk' off of the real disk file and into the cache of pFile.
*/
static int readBlockIntoCache(crashFile *pFile, int blk){
  if( blk>=pFile->nBlk ){
    int n = ((pFile->nBlk * 2) + 100 + blk);
    /* if( pFile->nBlk==0 ){ printf("DIRTY %s\n", pFile->zName); } */
    pFile->apBlk = (u8 **)sqliteRealloc(pFile->apBlk, n * sizeof(u8*));
    if( !pFile->apBlk ) return SQLITE_NOMEM;
    memset(&pFile->apBlk[pFile->nBlk], 0, (n - pFile->nBlk)*sizeof(u8*));
    pFile->nBlk = n;
................................................................................
    i64 filesize;
    int rc;

    u8 *p = sqliteMalloc(BLOCKSIZE);
    if( !p ) return SQLITE_NOMEM;
    pFile->apBlk[blk] = p;

    rc = sqlite3OsFileSize(pFile->pBase, &filesize);
    if( rc!=SQLITE_OK ) return rc;

    if( BLOCK_OFFSET(blk)<filesize ){
      int len = BLOCKSIZE;
      rc = sqlite3OsSeek(pFile->pBase, blk*BLOCKSIZE);
      if( BLOCK_OFFSET(blk+1)>filesize ){
        len = filesize - BLOCK_OFFSET(blk);
      }
      if( rc!=SQLITE_OK ) return rc;
      rc = sqlite3OsRead(pFile->pBase, p, len);
      if( rc!=SQLITE_OK ) return rc;
    }
  }

  return SQLITE_OK;
}

/*
** Write the cache of pFile to disk. If crash is non-zero, randomly
** skip blocks when writing. The cache is deleted before returning.
*/
static int writeCache2(crashFile *pFile, int crash){
  int i;
  int nMax = pFile->nMaxWrite;
  int rc = SQLITE_OK;

  for(i=0; i<pFile->nBlk; i++){
    u8 *p = pFile->apBlk[i];
    if( p ){
................................................................................
        }else{
#ifdef TRACE_WRITECACHE
printf("Writing block %d of %s\n", i, pFile->zName); 
#endif
        }
      }
      if( rc==SQLITE_OK ){
        rc = sqlite3OsSeek(pFile->pBase, BLOCK_OFFSET(i));
      }
      if( rc==SQLITE_OK && !skip ){
        int len = BLOCKSIZE;
        if( BLOCK_OFFSET(i+1)>nMax ){
          len = nMax-BLOCK_OFFSET(i);
        }
        if( len>0 ){
          if( trash ){
            sqlite3Randomness(len, p);
          }
          rc = sqlite3OsWrite(pFile->pBase, p, len);
        }
      }
      sqliteFree(p);
    }
  }
  sqliteFree(pFile->apBlk);
  pFile->nBlk = 0;
................................................................................
  pFile->nMaxWrite = 0;
  return rc;
}

/*
** Write the cache to disk.
*/
static int writeCache(crashFile *pFile){
  if( pFile->apBlk ){
    int c = crashRequired(pFile->zName);
    if( c ){
      crashFile *p;
#ifdef TRACE_WRITECACHE
      printf("\nCrash during sync of %s\n", pFile->zName);
#endif
      for(p=pAllFiles; p; p=p->pNext){
        writeCache2(p, 1);
      }
      exit(-1);
................................................................................
  return SQLITE_OK;
}

/*
** Close the file.
*/
static int crashClose(OsFile **pId){
  crashFile *pFile = (crashFile*)*pId;
  if( pFile ){
    /* printf("CLOSE %s (%d blocks)\n", pFile->zName, pFile->nBlk); */
    writeCache(pFile);
    sqlite3OsClose(&pFile->pBase);
  }
  closeFile(&pFile);
  *pId = 0;
  return SQLITE_OK;
}

static int crashSeek(OsFile *id, i64 offset){
  ((crashFile*)id)->offset = offset;
  return SQLITE_OK;
}

static int crashRead(OsFile *id, void *pBuf, int amt){
  i64 offset;       /* The current offset from the start of the file */
  i64 end;          /* The byte just past the last byte read */
  int blk;            /* Block number the read starts on */
  int i;
  u8 *zCsr;
  int rc = SQLITE_OK;
  crashFile *pFile = (crashFile*)id;

  offset = pFile->offset;
  end = offset+amt;
  blk = (offset/BLOCKSIZE);

  zCsr = (u8 *)pBuf;
  for(i=blk; i*BLOCKSIZE<end; i++){
................................................................................
      len = len - (BLOCK_OFFSET(i+1)-end);
    }

    if( i<pFile->nBlk && pFile->apBlk[i]){
      u8 *pBlk = pFile->apBlk[i];
      memcpy(zCsr, &pBlk[off], len);
    }else{
      rc = sqlite3OsSeek(pFile->pBase, BLOCK_OFFSET(i) + off);
      if( rc!=SQLITE_OK ) return rc;
      rc = sqlite3OsRead(pFile->pBase, zCsr, len);
      if( rc!=SQLITE_OK ) return rc;
    }

    zCsr += len;
  }
  assert( zCsr==&((u8 *)pBuf)[amt] );

  pFile->offset = end;
  return rc;
}

static int crashWrite(OsFile *id, const void *pBuf, int amt){
  i64 offset;       /* The current offset from the start of the file */
  i64 end;          /* The byte just past the last byte written */
  int blk;            /* Block number the write starts on */
  int i;
  const u8 *zCsr;
  int rc = SQLITE_OK;
  crashFile *pFile = (crashFile*)id;

  offset = pFile->offset;
  end = offset+amt;
  blk = (offset/BLOCKSIZE);

  zCsr = (u8 *)pBuf;
  for(i=blk; i*BLOCKSIZE<end; i++){
    u8 *pBlk;
    int off = 0;
    int len = 0;

    /* Make sure the block is in the cache */
    rc = readBlockIntoCache(pFile, i);
    if( rc!=SQLITE_OK ) return rc;

    /* Write into the cache */
    pBlk = pFile->apBlk[i];
    assert( pBlk );

    if( BLOCK_OFFSET(i) < offset ){
      off = offset-BLOCK_OFFSET(i);
    }
    len = BLOCKSIZE - off;
    if( BLOCK_OFFSET(i+1) > end ){
      len = len - (BLOCK_OFFSET(i+1)-end);
    }
    memcpy(&pBlk[off], zCsr, len);
    zCsr += len;
  }
  if( pFile->nMaxWrite<end ){
    pFile->nMaxWrite = end;
  }
  assert( zCsr==&((u8 *)pBuf)[amt] );
  pFile->offset = end;
  return rc;
}

/*
** Sync the file. First flush the write-cache to disk, then call the
** real sync() function.
*/
static int crashSync(OsFile *id, int dataOnly){


  return writeCache((crashFile*)id);


}

/*
** Truncate the file. Set the internal OsFile.nMaxWrite variable to the new
** file size to ensure that nothing in the write-cache past this point
** is written to disk.
*/
static int crashTruncate(OsFile *id, i64 nByte){
  crashFile *pFile = (crashFile*)id;
  pFile->nMaxWrite = nByte;
  return sqlite3OsTruncate(pFile->pBase, nByte);
}

/*
** Return the size of the file. If the cache contains a write that extended
** the file, then return this size instead of the on-disk size.
*/
static int crashFileSize(OsFile *id, i64 *pSize){
  crashFile *pFile = (crashFile*)id;
  int rc = sqlite3OsFileSize(pFile->pBase, pSize);
  if( rc==SQLITE_OK && pSize && *pSize<pFile->nMaxWrite ){
    *pSize = pFile->nMaxWrite;
  }
  return rc;
}

/*
** The three functions used to open files. All that is required is to
** initialise the os_test.c specific fields and then call the corresponding
** os_unix.c function to really open the file.
*/
static int crashOpenReadWrite(const char *zFilename, OsFile **pId,int *pRdonly){
  OsFile *pBase = 0;
  int rc = origOs.xOpenReadWrite(zFilename, &pBase, pRdonly);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}
static int crashOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
  OsFile *pBase = 0;
  int rc = origOs.xOpenExclusive(zFilename, &pBase, delFlag);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}
static int crashOpenReadOnly(const char *zFilename, OsFile **pId){
  OsFile *pBase = 0;
  int rc = origOs.xOpenReadOnly(zFilename, &pBase);
  if( !rc ){
    initFile(pId, zFilename, pBase);
  }
  return rc;
}

/*
** OpenDirectory is a no-op
*/
static int crashOpenDir(OsFile *id, const char *zName){



  return SQLITE_OK;
}

/*
** Locking primitives are passed through into the underlying
** file descriptor.
*/
int crashLock(OsFile *id, int lockType){
  return sqlite3OsLock(((crashFile*)id)->pBase, lockType);
}
int crashUnlock(OsFile *id, int lockType){
  return sqlite3OsUnlock(((crashFile*)id)->pBase, lockType);
}
int crashCheckReservedLock(OsFile *id){
  return sqlite3OsCheckReservedLock(((crashFile*)id)->pBase);
}
void crashSetFullSync(OsFile *id, int setting){
  return;  /* This is a no-op */
}
int crashLockState(OsFile *id){
  return sqlite3OsLockState(((crashFile*)id)->pBase);
}

/*
** Return the underlying file handle.
*/
int crashFileHandle(OsFile *id){
  return sqlite3OsFileHandle(((crashFile*)id)->pBase);
}

/*
** This vector defines all the methods that can operate on an OsFile
** for the crash tester.
*/
static const IoMethod crashIoMethod = {
  crashClose,
  crashOpenDir,
  crashRead,
  crashWrite,
  crashSeek,
  crashTruncate,
  crashSync,
  crashSetFullSync,
  crashFileHandle,
  crashFileSize,
  crashLock,
  crashUnlock,
  crashLockState,
  crashCheckReservedLock,
};


/*
** Initialise the os_test.c specific fields of pFile.
*/
static void initFile(OsFile **pId, char const *zName, OsFile *pBase){
  crashFile *pFile = sqliteMalloc(sizeof(crashFile) + strlen(zName)+1);
  pFile->pMethod = &crashIoMethod;
  pFile->nMaxWrite = 0; 
  pFile->offset = 0;
  pFile->nBlk = 0; 
  pFile->apBlk = 0; 
  pFile->zName = (char *)(&pFile[1]);
  strcpy(pFile->zName, zName);
  pFile->pBase = pBase;
  pFile->pNext = pAllFiles;
  pAllFiles = pFile;
  *pId = (OsFile*)pFile;
}


/*
** tclcmd:   sqlite_crashparams DELAY CRASHFILE
**
** This procedure implements a TCL command that enables crash testing
** in testfixture.  Once enabled, crash testing cannot be disabled.
*/
................................................................................
  if( Tcl_GetIntFromObj(interp, objv[1], &delay) ) return TCL_ERROR;
  zFile = Tcl_GetStringFromObj(objv[2], &nFile);
  if( nFile>=sizeof(zCrashFile)-1 ){
    Tcl_AppendResult(interp, "crash file name too big", 0);
    return TCL_ERROR;
  }
  setCrashParams(delay, zFile);
  if( origOs.xOpenReadWrite==0 ){
    origOs = sqlite3Os;


    sqlite3Os.xOpenReadWrite = crashOpenReadWrite;
    sqlite3Os.xOpenExclusive = crashOpenExclusive;
    sqlite3Os.xOpenReadOnly = crashOpenReadOnly;


















  }
  return TCL_OK;
}

/*
** This procedure registers the TCL procedures defined in this file.
*/
int Sqlitetest6_Init(Tcl_Interp *interp){
  Tcl_CreateObjCommand(interp, "sqlite3_crashparams", crashParamsObjCmd, 0, 0);
  return TCL_OK;
}

#endif /* SQLITE_TEST */

Changes to src/vacuum.c.

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**
*************************************************************************
** This file contains code used to implement the VACUUM command.
**
** Most of the code in this file may be omitted by defining the
** SQLITE_OMIT_VACUUM macro.
**
** $Id: vacuum.c,v 1.48 2005/11/26 00:25:04 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"

#ifndef SQLITE_OMIT_VACUUM
/*
** Generate a random name of 20 character in length.
................................................................................
  ** run more than once or twice is vanishingly small.  We are certain
  ** enough that this loop will always terminate (and terminate quickly)
  ** that we don't even bother to set a maximum loop count.
  */
  do {
    zTemp[nFilename] = '-';
    randomName((unsigned char*)&zTemp[nFilename+1]);
  } while( sqlite3Io.xFileExists(zTemp) );

  /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
  ** can be set to 'off' for this file, as it is not recovered if a crash
  ** occurs anyway. The integrity of the database is maintained by a
  ** (possibly synchronous) transaction opened on the main database before
  ** sqlite3BtreeCopyFile() is called.
  **
................................................................................
  */
  db->autoCommit = 1;
  rc2 = execSql(db, "DETACH vacuum_db;");
  if( rc==SQLITE_OK ){
    rc = rc2;
  }
  if( zTemp ){
    sqlite3Io.xDelete(zTemp);
    sqliteFree(zTemp);
  }
  sqliteFree( zSql );
  sqlite3ResetInternalSchema(db, 0);
#endif

  return rc;
}







|







 







|







 







|








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**
*************************************************************************
** This file contains code used to implement the VACUUM command.
**
** Most of the code in this file may be omitted by defining the
** SQLITE_OMIT_VACUUM macro.
**
** $Id: vacuum.c,v 1.49 2005/11/30 03:20:32 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"

#ifndef SQLITE_OMIT_VACUUM
/*
** Generate a random name of 20 character in length.
................................................................................
  ** run more than once or twice is vanishingly small.  We are certain
  ** enough that this loop will always terminate (and terminate quickly)
  ** that we don't even bother to set a maximum loop count.
  */
  do {
    zTemp[nFilename] = '-';
    randomName((unsigned char*)&zTemp[nFilename+1]);
  } while( sqlite3Os.xFileExists(zTemp) );

  /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
  ** can be set to 'off' for this file, as it is not recovered if a crash
  ** occurs anyway. The integrity of the database is maintained by a
  ** (possibly synchronous) transaction opened on the main database before
  ** sqlite3BtreeCopyFile() is called.
  **
................................................................................
  */
  db->autoCommit = 1;
  rc2 = execSql(db, "DETACH vacuum_db;");
  if( rc==SQLITE_OK ){
    rc = rc2;
  }
  if( zTemp ){
    sqlite3Os.xDelete(zTemp);
    sqliteFree(zTemp);
  }
  sqliteFree( zSql );
  sqlite3ResetInternalSchema(db, 0);
#endif

  return rc;
}

Changes to src/vdbe.c.

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**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.500 2005/11/26 00:25:04 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
    if( p->trace ){
      if( pc==0 ){
        printf("VDBE Execution Trace:\n");
        sqlite3VdbePrintSql(p);
      }
      sqlite3VdbePrintOp(p->trace, pc, pOp);
    }
    if( p->trace==0 && pc==0 && sqlite3Io.xFileExists("vdbe_sqltrace") ){
      sqlite3VdbePrintSql(p);
    }
#endif
      

    /* Check to see if we need to simulate an interrupt.  This only happens
    ** if we have a special test build.







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**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.501 2005/11/30 03:20:32 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
    if( p->trace ){
      if( pc==0 ){
        printf("VDBE Execution Trace:\n");
        sqlite3VdbePrintSql(p);
      }
      sqlite3VdbePrintOp(p->trace, pc, pOp);
    }
    if( p->trace==0 && pc==0 && sqlite3Os.xFileExists("vdbe_sqltrace") ){
      sqlite3VdbePrintSql(p);
    }
#endif
      

    /* Check to see if we need to simulate an interrupt.  This only happens
    ** if we have a special test build.

Changes to src/vdbeapi.c.

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      if( sqlite3SafetyOn(db) ){
        p->rc = SQLITE_MISUSE;
        return SQLITE_MISUSE;
      }
    }
    if( db->xProfile && !db->init.busy ){
      double rNow;
      sqlite3OsCurrentTime(&rNow);
      p->startTime = (rNow - (int)rNow)*3600.0*24.0*1000000000.0;
    }
#endif

    /* Print a copy of SQL as it is executed if the SQL_TRACE pragma is turned
    ** on in debugging mode.
    */
................................................................................
#ifndef SQLITE_OMIT_TRACE
  /* Invoke the profile callback if there is one
  */
  if( rc!=SQLITE_ROW && db->xProfile && !db->init.busy ){
    double rNow;
    u64 elapseTime;

    sqlite3OsCurrentTime(&rNow);
    elapseTime = (rNow - (int)rNow)*3600.0*24.0*1000000000.0 - p->startTime;
    assert( p->nOp>0 );
    assert( p->aOp[p->nOp-1].opcode==OP_Noop );
    assert( p->aOp[p->nOp-1].p3!=0 );
    assert( p->aOp[p->nOp-1].p3type==P3_DYNAMIC );
    db->xProfile(db->pProfileArg, p->aOp[p->nOp-1].p3, elapseTime);
  }







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      if( sqlite3SafetyOn(db) ){
        p->rc = SQLITE_MISUSE;
        return SQLITE_MISUSE;
      }
    }
    if( db->xProfile && !db->init.busy ){
      double rNow;
      sqlite3Os.xCurrentTime(&rNow);
      p->startTime = (rNow - (int)rNow)*3600.0*24.0*1000000000.0;
    }
#endif

    /* Print a copy of SQL as it is executed if the SQL_TRACE pragma is turned
    ** on in debugging mode.
    */
................................................................................
#ifndef SQLITE_OMIT_TRACE
  /* Invoke the profile callback if there is one
  */
  if( rc!=SQLITE_ROW && db->xProfile && !db->init.busy ){
    double rNow;
    u64 elapseTime;

    sqlite3Os.xCurrentTime(&rNow);
    elapseTime = (rNow - (int)rNow)*3600.0*24.0*1000000000.0 - p->startTime;
    assert( p->nOp>0 );
    assert( p->aOp[p->nOp-1].opcode==OP_Noop );
    assert( p->aOp[p->nOp-1].p3!=0 );
    assert( p->aOp[p->nOp-1].p3type==P3_DYNAMIC );
    db->xProfile(db->pProfileArg, p->aOp[p->nOp-1].p3, elapseTime);
  }

Changes to src/vdbeaux.c.

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  p->aLabel = 0;

  *pMaxFuncArgs = nMaxArgs;
  *pMaxStack = nMaxStack;

  /* If we never rollback a statement transaction, then statement
  ** transactions are not needed.  So change every OP_Statement
  ** opcode into an OP_Noop.  This avoid a call to sqlite3Io.xOpenExclusive()
  ** which can be expensive on some platforms.
  */
  if( hasStatementBegin && !doesStatementRollback ){
    for(pOp=p->aOp, i=p->nOp-1; i>=0; i--, pOp++){
      if( pOp->opcode==OP_Statement ){
        pOp->opcode = OP_Noop;
      }
................................................................................
  }
  for(n=0; n<p->nMem; n++){
    p->aMem[n].flags = MEM_Null;
  }

#ifdef SQLITE_DEBUG
  if( (p->db->flags & SQLITE_VdbeListing)!=0
    || sqlite3Io.xFileExists("vdbe_explain")
  ){
    int i;
    printf("VDBE Program Listing:\n");
    sqlite3VdbePrintSql(p);
    for(i=0; i<p->nOp; i++){
      sqlite3VdbePrintOp(stdout, i, &p->aOp[i]);
    }
  }
  if( sqlite3Io.xFileExists("vdbe_trace") ){
    p->trace = stdout;
  }
#endif
  p->pTos = &p->aStack[-1];
  p->pc = -1;
  p->rc = SQLITE_OK;
  p->uniqueCnt = 0;
................................................................................
      u32 random;
      sqliteFree(zMaster);
      sqlite3Randomness(sizeof(random), &random);
      zMaster = sqlite3MPrintf("%s-mj%08X", zMainFile, random&0x7fffffff);
      if( !zMaster ){
        return SQLITE_NOMEM;
      }
    }while( sqlite3Io.xFileExists(zMaster) );

    /* Open the master journal. */
    rc = sqlite3Io.xOpenExclusive(zMaster, &master, 0);
    if( rc!=SQLITE_OK ){
      sqliteFree(zMaster);
      return rc;
    }
 
    /* Write the name of each database file in the transaction into the new
    ** master journal file. If an error occurs at this point close
................................................................................
      if( i==1 ) continue;   /* Ignore the TEMP database */
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        char const *zFile = sqlite3BtreeGetJournalname(pBt);
        if( zFile[0]==0 ) continue;  /* Ignore :memory: databases */
        if( !needSync && !sqlite3BtreeSyncDisabled(pBt) ){
          needSync = 1;
        }
        rc = sqlite3Io.xWrite(master, zFile, strlen(zFile)+1);
        if( rc!=SQLITE_OK ){
          sqlite3Io.xClose(&master);
          sqlite3Io.xDelete(zMaster);
          sqliteFree(zMaster);
          return rc;
        }
      }
    }


    /* Sync the master journal file. Before doing this, open the directory
    ** the master journal file is store in so that it gets synced too.
    */
    zMainFile = sqlite3BtreeGetDirname(db->aDb[0].pBt);
    rc = sqlite3Io.xOpenDirectory(zMainFile, master);
    if( rc!=SQLITE_OK ||
          (needSync && (rc=sqlite3Io.xSync(master,0))!=SQLITE_OK) ){
      sqlite3Io.xClose(&master);
      sqlite3Io.xDelete(zMaster);
      sqliteFree(zMaster);
      return rc;
    }

    /* Sync all the db files involved in the transaction. The same call
    ** sets the master journal pointer in each individual journal. If
    ** an error occurs here, do not delete the master journal file.
................................................................................
    ** occured.
    */
    for(i=0; i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        rc = sqlite3BtreeSync(pBt, zMaster);
        if( rc!=SQLITE_OK ){
          sqlite3Io.xClose(&master);
          sqliteFree(zMaster);
          return rc;
        }
      }
    }
    sqlite3Io.xClose(&master);

    /* Delete the master journal file. This commits the transaction. After
    ** doing this the directory is synced again before any individual
    ** transaction files are deleted.
    */
    rc = sqlite3Io.xDelete(zMaster);
    assert( rc==SQLITE_OK );
    sqliteFree(zMaster);
    zMaster = 0;
    rc = sqlite3Io.xSyncDirectory(zMainFile);
    if( rc!=SQLITE_OK ){
      /* This is not good. The master journal file has been deleted, but
      ** the directory sync failed. There is no completely safe course of
      ** action from here. The individual journals contain the name of the
      ** master journal file, but there is no way of knowing if that
      ** master journal exists now or if it will exist after the operating
      ** system crash that may follow the fsync() failure.







|







 







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  p->aLabel = 0;

  *pMaxFuncArgs = nMaxArgs;
  *pMaxStack = nMaxStack;

  /* If we never rollback a statement transaction, then statement
  ** transactions are not needed.  So change every OP_Statement
  ** opcode into an OP_Noop.  This avoid a call to sqlite3Os.xOpenExclusive()
  ** which can be expensive on some platforms.
  */
  if( hasStatementBegin && !doesStatementRollback ){
    for(pOp=p->aOp, i=p->nOp-1; i>=0; i--, pOp++){
      if( pOp->opcode==OP_Statement ){
        pOp->opcode = OP_Noop;
      }
................................................................................
  }
  for(n=0; n<p->nMem; n++){
    p->aMem[n].flags = MEM_Null;
  }

#ifdef SQLITE_DEBUG
  if( (p->db->flags & SQLITE_VdbeListing)!=0
    || sqlite3Os.xFileExists("vdbe_explain")
  ){
    int i;
    printf("VDBE Program Listing:\n");
    sqlite3VdbePrintSql(p);
    for(i=0; i<p->nOp; i++){
      sqlite3VdbePrintOp(stdout, i, &p->aOp[i]);
    }
  }
  if( sqlite3Os.xFileExists("vdbe_trace") ){
    p->trace = stdout;
  }
#endif
  p->pTos = &p->aStack[-1];
  p->pc = -1;
  p->rc = SQLITE_OK;
  p->uniqueCnt = 0;
................................................................................
      u32 random;
      sqliteFree(zMaster);
      sqlite3Randomness(sizeof(random), &random);
      zMaster = sqlite3MPrintf("%s-mj%08X", zMainFile, random&0x7fffffff);
      if( !zMaster ){
        return SQLITE_NOMEM;
      }
    }while( sqlite3Os.xFileExists(zMaster) );

    /* Open the master journal. */
    rc = sqlite3Os.xOpenExclusive(zMaster, &master, 0);
    if( rc!=SQLITE_OK ){
      sqliteFree(zMaster);
      return rc;
    }
 
    /* Write the name of each database file in the transaction into the new
    ** master journal file. If an error occurs at this point close
................................................................................
      if( i==1 ) continue;   /* Ignore the TEMP database */
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        char const *zFile = sqlite3BtreeGetJournalname(pBt);
        if( zFile[0]==0 ) continue;  /* Ignore :memory: databases */
        if( !needSync && !sqlite3BtreeSyncDisabled(pBt) ){
          needSync = 1;
        }
        rc = sqlite3OsWrite(master, zFile, strlen(zFile)+1);
        if( rc!=SQLITE_OK ){
          sqlite3OsClose(&master);
          sqlite3Os.xDelete(zMaster);
          sqliteFree(zMaster);
          return rc;
        }
      }
    }


    /* Sync the master journal file. Before doing this, open the directory
    ** the master journal file is store in so that it gets synced too.
    */
    zMainFile = sqlite3BtreeGetDirname(db->aDb[0].pBt);
    rc = sqlite3OsOpenDirectory(master, zMainFile);
    if( rc!=SQLITE_OK ||
          (needSync && (rc=sqlite3OsSync(master,0))!=SQLITE_OK) ){
      sqlite3OsClose(&master);
      sqlite3Os.xDelete(zMaster);
      sqliteFree(zMaster);
      return rc;
    }

    /* Sync all the db files involved in the transaction. The same call
    ** sets the master journal pointer in each individual journal. If
    ** an error occurs here, do not delete the master journal file.
................................................................................
    ** occured.
    */
    for(i=0; i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        rc = sqlite3BtreeSync(pBt, zMaster);
        if( rc!=SQLITE_OK ){
          sqlite3OsClose(&master);
          sqliteFree(zMaster);
          return rc;
        }
      }
    }
    sqlite3OsClose(&master);

    /* Delete the master journal file. This commits the transaction. After
    ** doing this the directory is synced again before any individual
    ** transaction files are deleted.
    */
    rc = sqlite3Os.xDelete(zMaster);
    assert( rc==SQLITE_OK );
    sqliteFree(zMaster);
    zMaster = 0;
    rc = sqlite3Os.xSyncDirectory(zMainFile);
    if( rc!=SQLITE_OK ){
      /* This is not good. The master journal file has been deleted, but
      ** the directory sync failed. There is no completely safe course of
      ** action from here. The individual journals contain the name of the
      ** master journal file, but there is no way of knowing if that
      ** master journal exists now or if it will exist after the operating
      ** system crash that may follow the fsync() failure.