** 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.
**
*************************************************************************
** $Id: btree.c,v 1.400 2007/08/17 15:53:36 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"

................................................................................
  ** existing BtShared object that we can share with
  */
  if( (flags & BTREE_PRIVATE)==0
   && isMemdb==0
   && zFilename && zFilename[0]
   && sqlite3SharedCacheEnabled
  ){
    char *zFullPathname = sqlite3OsFullPathname(zFilename);
    sqlite3_mutex *mutexShared;
    p->sharable = 1;
    if( !zFullPathname ){
      sqlite3_free(p);
      return SQLITE_NOMEM;
    }

    mutexShared = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
    sqlite3_mutex_enter(mutexShared);
    for(pBt=sqlite3SharedCacheList; pBt; pBt=pBt->pNext){
      assert( pBt->nRef>0 );
      if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager)) ){
        p->pBt = pBt;
        pBt->nRef++;

** 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.
**
*************************************************************************
** $Id: btree.c,v 1.401 2007/08/17 16:50:38 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"

................................................................................
  ** existing BtShared object that we can share with
  */
  if( (flags & BTREE_PRIVATE)==0
   && isMemdb==0
   && zFilename && zFilename[0]
   && sqlite3SharedCacheEnabled
  ){
    char *zFullPathname = (char *)sqlite3_malloc(pVfs->mxPathname);
    sqlite3_mutex *mutexShared;
    p->sharable = 1;
    if( !zFullPathname ){
      sqlite3_free(p);
      return SQLITE_NOMEM;
    }
    sqlite3OsFullPathname(pVfs, zFilename, zFullPathname);
    mutexShared = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
    sqlite3_mutex_enter(mutexShared);
    for(pBt=sqlite3SharedCacheList; pBt; pBt=pBt->pNext){
      assert( pBt->nRef>0 );
      if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager)) ){
        p->pBt = pBt;
        pBt->nRef++;

}
int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
  return id->pMethods->xWrite(id, pBuf, amt, offset);
}
int sqlite3OsTruncate(sqlite3_file *id, i64 size){
  return id->pMethods->xTruncate(id, size);
}
int sqlite3OsSync(sqlite3_file *id, int fullsync){
  return id->pMethods->xSync(id, fullsync);
}
int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
  return id->pMethods->xFileSize(id, pSize);
}
int sqlite3OsLock(sqlite3_file *id, int lockType){
  return id->pMethods->xLock(id, lockType);
}
................................................................................
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  /* These methods are currently only used for testing and debugging. */
  int sqlite3OsFileHandle(sqlite3_file *id){
    /* return id->pMethods->xFileHandle(id); */
    return 0;
  }
  int sqlite3OsLockState(sqlite3_file *id){
    /* return id->pMethods->xLockState(id); */
    return 0;
  }
#endif

int sqlite3OsOpen(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  sqlite3_file *pFile, 

}
int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
  return id->pMethods->xWrite(id, pBuf, amt, offset);
}
int sqlite3OsTruncate(sqlite3_file *id, i64 size){
  return id->pMethods->xTruncate(id, size);
}
int sqlite3OsSync(sqlite3_file *id, int flags){
  return id->pMethods->xSync(id, flags);
}
int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
  return id->pMethods->xFileSize(id, pSize);
}
int sqlite3OsLock(sqlite3_file *id, int lockType){
  return id->pMethods->xLock(id, lockType);
}
................................................................................
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  /* These methods are currently only used for testing and debugging. */
  int sqlite3OsFileHandle(sqlite3_file *id){
    /* return id->pMethods->xFileHandle(id); */
    return 0;
  }
  int sqlite3OsLockState(sqlite3_file *id){
    return id->pMethods->xLockState(id);

  }
#endif

int sqlite3OsOpen(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  sqlite3_file *pFile, 

** anybody smart enough to figure out the code is also likely smart
** enough to know that calling the developer will not help get rid
** of the file.
*/
#ifndef TEMP_FILE_PREFIX
# define TEMP_FILE_PREFIX "etilqs_"
#endif

#if 0

/*
** Define the interfaces for Unix, Windows, and OS/2.
*/
#if OS_UNIX
#define sqlite3OsOpenReadWrite      sqlite3UnixOpenReadWrite
#define sqlite3OsOpenExclusive      sqlite3UnixOpenExclusive
#define sqlite3OsOpenReadOnly       sqlite3UnixOpenReadOnly
#define sqlite3OsDelete             sqlite3UnixDelete
#define sqlite3OsFileExists         sqlite3UnixFileExists
#define sqlite3OsFullPathname       sqlite3UnixFullPathname
#define sqlite3OsIsDirWritable      sqlite3UnixIsDirWritable
#define sqlite3OsSyncDirectory      sqlite3UnixSyncDirectory
#define sqlite3OsTempFileName       sqlite3UnixTempFileName
#define sqlite3OsRandomSeed         sqlite3UnixRandomSeed
#define sqlite3OsSleep              sqlite3UnixSleep
#define sqlite3OsCurrentTime        sqlite3UnixCurrentTime
#define sqlite3OsEnterMutex         sqlite3UnixEnterMutex
#define sqlite3OsLeaveMutex         sqlite3UnixLeaveMutex
#define sqlite3OsInMutex            sqlite3UnixInMutex
#define sqlite3OsThreadSpecificData sqlite3UnixThreadSpecificData
#define sqlite3OsMalloc             sqlite3GenericMalloc
#define sqlite3OsRealloc            sqlite3GenericRealloc
#define sqlite3OsFree               sqlite3GenericFree
#define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
#define sqlite3OsDlopen             sqlite3UnixDlopen
#define sqlite3OsDlsym              sqlite3UnixDlsym
#define sqlite3OsDlclose            sqlite3UnixDlclose
#endif
#if OS_WIN
#define sqlite3OsOpenReadWrite      sqlite3WinOpenReadWrite
#define sqlite3OsOpenExclusive      sqlite3WinOpenExclusive
#define sqlite3OsOpenReadOnly       sqlite3WinOpenReadOnly
#define sqlite3OsDelete             sqlite3WinDelete
#define sqlite3OsFileExists         sqlite3WinFileExists
#define sqlite3OsFullPathname       sqlite3WinFullPathname
#define sqlite3OsIsDirWritable      sqlite3WinIsDirWritable
#define sqlite3OsSyncDirectory      sqlite3WinSyncDirectory
#define sqlite3OsTempFileName       sqlite3WinTempFileName
#define sqlite3OsRandomSeed         sqlite3WinRandomSeed
#define sqlite3OsSleep              sqlite3WinSleep
#define sqlite3OsCurrentTime        sqlite3WinCurrentTime
#define sqlite3OsEnterMutex         sqlite3WinEnterMutex
#define sqlite3OsLeaveMutex         sqlite3WinLeaveMutex
#define sqlite3OsInMutex            sqlite3WinInMutex
#define sqlite3OsThreadSpecificData sqlite3WinThreadSpecificData
#define sqlite3OsMalloc             sqlite3GenericMalloc
#define sqlite3OsRealloc            sqlite3GenericRealloc
#define sqlite3OsFree               sqlite3GenericFree
#define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
#define sqlite3OsDlopen             sqlite3WinDlopen
#define sqlite3OsDlsym              sqlite3WinDlsym
#define sqlite3OsDlclose            sqlite3WinDlclose
#endif
#if OS_OS2
#define sqlite3OsOpenReadWrite      sqlite3Os2OpenReadWrite
#define sqlite3OsOpenExclusive      sqlite3Os2OpenExclusive
#define sqlite3OsOpenReadOnly       sqlite3Os2OpenReadOnly
#define sqlite3OsDelete             sqlite3Os2Delete
#define sqlite3OsFileExists         sqlite3Os2FileExists
#define sqlite3OsFullPathname       sqlite3Os2FullPathname
#define sqlite3OsIsDirWritable      sqlite3Os2IsDirWritable
#define sqlite3OsSyncDirectory      sqlite3Os2SyncDirectory
#define sqlite3OsTempFileName       sqlite3Os2TempFileName
#define sqlite3OsRandomSeed         sqlite3Os2RandomSeed
#define sqlite3OsSleep              sqlite3Os2Sleep
#define sqlite3OsCurrentTime        sqlite3Os2CurrentTime
#define sqlite3OsEnterMutex         sqlite3Os2EnterMutex
#define sqlite3OsLeaveMutex         sqlite3Os2LeaveMutex
#define sqlite3OsInMutex            sqlite3Os2InMutex
#define sqlite3OsThreadSpecificData sqlite3Os2ThreadSpecificData
#define sqlite3OsMalloc             sqlite3GenericMalloc
#define sqlite3OsRealloc            sqlite3GenericRealloc
#define sqlite3OsFree               sqlite3GenericFree
#define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
#define sqlite3OsDlopen             sqlite3Os2Dlopen
#define sqlite3OsDlsym              sqlite3Os2Dlsym
#define sqlite3OsDlclose            sqlite3Os2Dlclose
#endif

#endif



/*
** If using an alternative OS interface, then we must have an "os_other.h"
** header file available for that interface.  Presumably the "os_other.h"
** header file contains #defines similar to those above.
*/
#if OS_OTHER
# include "os_other.h"
#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);
  int (*xSectorSize)(OsFile *id);
};

/*
** The OsFile object describes an open disk file in an OS-dependent way.
** The version of OsFile defined here is a generic version.  Each OS
** implementation defines its own subclass of this structure that contains
** additional information needed to handle file I/O.  But the pMethod
** entry (pointing to the virtual function table) always occurs first
** so that we can always find the appropriate methods.
*/
struct OsFile {
  IoMethod const *pMethod;
};

/*
** The following values may be passed as the second argument to
** sqlite3OsLock(). The various locks exhibit the following semantics:
**
** SHARED:    Any number of processes may hold a SHARED lock simultaneously.
** RESERVED:  A single process may hold a RESERVED lock on a file at
**            any time. Other processes may hold and obtain new SHARED locks.
................................................................................
int sqlite3OsTruncate(sqlite3_file*, i64 size);
int sqlite3OsSync(sqlite3_file*, int);
int sqlite3OsFileSize(sqlite3_file*, i64 *pSize);
int sqlite3OsLock(sqlite3_file*, int);
int sqlite3OsUnlock(sqlite3_file*, int);
int sqlite3OsBreakLock(sqlite3_file*);
int sqlite3OsCheckReservedLock(sqlite3_file *id);

int sqlite3OsSectorSize(sqlite3_file *id);
int sqlite3OsDeviceCharacteristics(sqlite3_file *id);

/* 
** Functions for accessing sqlite3_vfs methods 
*/
int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *);
................................................................................
/*
** Convenience functions for opening and closing files using 
** sqlite3_malloc() to obtain space for the file-handle structure.
*/
int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int); 
int sqlite3OsCloseFree(sqlite3_file *);

#if 0
int sqlite3OsOpenReadWrite(const char*, sqlite3_file**, int*);
int sqlite3OsOpenExclusive(const char*, sqlite3_file**, int);
int sqlite3OsOpenReadOnly(const char*, sqlite3_file**);
int sqlite3OsDelete(const char*);
int sqlite3OsFileExists(const char*);
char *sqlite3OsFullPathname(const char*);
int sqlite3OsIsDirWritable(char*);
int sqlite3OsSyncDirectory(const char*);
int sqlite3OsTempFileName(char*);
int sqlite3OsRandomSeed(char*);
int sqlite3OsSleep(int ms);
int sqlite3OsCurrentTime(double*);
void sqlite3OsEnterMutex(void);
void sqlite3OsLeaveMutex(void);
int sqlite3OsInMutex(int);
ThreadData *sqlite3OsThreadSpecificData(int);
void *sqlite3OsMalloc(int);
void *sqlite3OsRealloc(void *, int);
void sqlite3OsFree(void *);
int sqlite3OsAllocationSize(void *);
void *sqlite3OsDlopen(const char*);
void *sqlite3OsDlsym(void*, const char*);
int sqlite3OsDlclose(void*);
#endif

#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  int sqlite3OsFileHandle(sqlite3_file *id);
  int sqlite3OsLockState(sqlite3_file *id);
#endif

/*
** If the SQLITE_ENABLE_REDEF_IO macro is defined, then the OS-layer
** interface routines are not called directly but are invoked using
** pointers to functions.  This allows the implementation of various
** OS-layer interface routines to be modified at run-time.  There are
** obscure but legitimate reasons for wanting to do this.  But for
** most users, a direct call to the underlying interface is preferable
** so the the redefinable I/O interface is turned off by default.
*/
#ifdef SQLITE_ENABLE_REDEF_IO

/*
** When redefinable I/O is enabled, a single global instance of the
** following structure holds pointers to the routines that SQLite 
** uses to talk with the underlying operating system.  Modify this
** structure (before using any SQLite API!) to accomodate perculiar
** operating system interfaces or behaviors.
*/
struct sqlite3OsVtbl {
  int (*xOpenReadWrite)(const char*, sqlite3_file**, int*);
  int (*xOpenExclusive)(const char*, sqlite3_file**, int);
  int (*xOpenReadOnly)(const char*, sqlite3_file**);

  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);
  int (*xInMutex)(int);
  ThreadData *(*xThreadSpecificData)(int);

  void *(*xMalloc)(int);
  void *(*xRealloc)(void *, int);
  void (*xFree)(void *);
  int (*xAllocationSize)(void *);

  void *(*xDlopen)(const char*);
  void *(*xDlsym)(void*, const char*);
  int (*xDlclose)(void*);
};

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


#if defined(_SQLITE_OS_C_) || defined(SQLITE_AMALGAMATION)
  /*
  ** The os.c file implements the global virtual function table.
  ** We have to put this file here because the initializers
  ** (ex: sqlite3OsRandomSeed) are macros that are about to be
  ** redefined.
  */
  struct sqlite3OsVtbl sqlite3Os = {
    IF_DISKIO( sqlite3OsOpenReadWrite ),
    IF_DISKIO( sqlite3OsOpenExclusive ),
    IF_DISKIO( sqlite3OsOpenReadOnly ),
    IF_DISKIO( sqlite3OsDelete ),
    IF_DISKIO( sqlite3OsFileExists ),
    IF_DISKIO( sqlite3OsFullPathname ),
    IF_DISKIO( sqlite3OsIsDirWritable ),
    IF_DISKIO( sqlite3OsSyncDirectory ),
    IF_DISKIO( sqlite3OsTempFileName ),
    sqlite3OsRandomSeed,
    sqlite3OsSleep,
    sqlite3OsCurrentTime,
    sqlite3OsEnterMutex,
    sqlite3OsLeaveMutex,
    sqlite3OsInMutex,
    0,
    sqlite3OsMalloc,
    sqlite3OsRealloc,
    sqlite3OsFree,
    sqlite3OsAllocationSize,
    IF_DLOPEN( sqlite3OsDlopen ),
    IF_DLOPEN( sqlite3OsDlsym ),
    IF_DLOPEN( sqlite3OsDlclose ),
  };
#else
  /*
  ** Files other than os.c just reference the global virtual function table. 
  */
  extern struct sqlite3OsVtbl sqlite3Os;
#endif /* _SQLITE_OS_C_ */


/* This additional API routine is available with redefinable I/O */
struct sqlite3OsVtbl *sqlite3_os_switch(void);


/*
** Redefine the OS interface to go through the virtual function table
** rather than calling routines directly.
*/
#undef sqlite3OsOpenReadWrite
#undef sqlite3OsOpenExclusive
#undef sqlite3OsOpenReadOnly
#undef sqlite3OsDelete
#undef sqlite3OsFileExists
#undef sqlite3OsFullPathname
#undef sqlite3OsIsDirWritable
#undef sqlite3OsSyncDirectory
#undef sqlite3OsTempFileName
#undef sqlite3OsRandomSeed
#undef sqlite3OsSleep
#undef sqlite3OsCurrentTime
#undef sqlite3OsEnterMutex
#undef sqlite3OsLeaveMutex
#undef sqlite3OsInMutex
#undef sqlite3OsThreadSpecificData
#undef sqlite3OsMalloc
#undef sqlite3OsRealloc
#undef sqlite3OsFree
#undef sqlite3OsAllocationSize
#define sqlite3OsOpenReadWrite      sqlite3Os.xOpenReadWrite
#define sqlite3OsOpenExclusive      sqlite3Os.xOpenExclusive
#define sqlite3OsOpenReadOnly       sqlite3Os.xOpenReadOnly
#define sqlite3OsDelete             sqlite3Os.xDelete
#define sqlite3OsFileExists         sqlite3Os.xFileExists
#define sqlite3OsFullPathname       sqlite3Os.xFullPathname
#define sqlite3OsIsDirWritable      sqlite3Os.xIsDirWritable
#define sqlite3OsSyncDirectory      sqlite3Os.xSyncDirectory
#define sqlite3OsTempFileName       sqlite3Os.xTempFileName
#define sqlite3OsRandomSeed         sqlite3Os.xRandomSeed
#define sqlite3OsSleep              sqlite3Os.xSleep
#define sqlite3OsCurrentTime        sqlite3Os.xCurrentTime
#define sqlite3OsEnterMutex         sqlite3Os.xEnterMutex
#define sqlite3OsLeaveMutex         sqlite3Os.xLeaveMutex
#define sqlite3OsInMutex            sqlite3Os.xInMutex
#define sqlite3OsThreadSpecificData sqlite3Os.xThreadSpecificData
#define sqlite3OsMalloc             sqlite3Os.xMalloc
#define sqlite3OsRealloc            sqlite3Os.xRealloc
#define sqlite3OsFree               sqlite3Os.xFree
#define sqlite3OsAllocationSize     sqlite3Os.xAllocationSize

#endif /* SQLITE_ENABLE_REDEF_IO */

#endif /* _SQLITE_OS_H_ */

** anybody smart enough to figure out the code is also likely smart
** enough to know that calling the developer will not help get rid
** of the file.
*/
#ifndef TEMP_FILE_PREFIX
# define TEMP_FILE_PREFIX "etilqs_"
#endif



/*



















































































** If using an alternative OS interface, then we must have an "os_other.h"
** header file available for that interface.  Presumably the "os_other.h"
** header file contains #defines similar to those above.
*/
#if OS_OTHER
# include "os_other.h"
#endif











































/*
** The following values may be passed as the second argument to
** sqlite3OsLock(). The various locks exhibit the following semantics:
**
** SHARED:    Any number of processes may hold a SHARED lock simultaneously.
** RESERVED:  A single process may hold a RESERVED lock on a file at
**            any time. Other processes may hold and obtain new SHARED locks.
................................................................................
int sqlite3OsTruncate(sqlite3_file*, i64 size);
int sqlite3OsSync(sqlite3_file*, int);
int sqlite3OsFileSize(sqlite3_file*, i64 *pSize);
int sqlite3OsLock(sqlite3_file*, int);
int sqlite3OsUnlock(sqlite3_file*, int);
int sqlite3OsBreakLock(sqlite3_file*);
int sqlite3OsCheckReservedLock(sqlite3_file *id);
int sqlite3OsLockState(sqlite3_file *id);
int sqlite3OsSectorSize(sqlite3_file *id);
int sqlite3OsDeviceCharacteristics(sqlite3_file *id);

/* 
** Functions for accessing sqlite3_vfs methods 
*/
int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *);
................................................................................
/*
** Convenience functions for opening and closing files using 
** sqlite3_malloc() to obtain space for the file-handle structure.
*/
int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int); 
int sqlite3OsCloseFree(sqlite3_file *);



























#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
  int sqlite3OsFileHandle(sqlite3_file *id);
  int sqlite3OsLockState(sqlite3_file *id);
#endif




























































































































































#endif /* _SQLITE_OS_H_ */

  struct lockInfo *pLock;   /* Info about locks on this inode */
#ifdef SQLITE_ENABLE_LOCKING_STYLE
  void *lockingContext;     /* Locking style specific state */
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
  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 */
  i64 offset;               /* Seek offset */
#ifdef SQLITE_UNIX_THREADS
  pthread_t tid;            /* The thread that "owns" this OsFile */
#endif
};

................................................................................
/*
** Return TRUE if the named file exists.
*/
int sqlite3UnixFileExists(const char *zFilename){
  return access(zFilename, 0)==0;
}

/* Forward declaration */
static int allocateUnixFile(
  int h,                    /* File descriptor of the open file */
  sqlite3_file **pId,       /* Write the real file descriptor here */
  const char *zFilename,    /* Name of the file being opened */
  int delFlag               /* If true, make sure the file deletes on close */
);

/*
** 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
** and *pReadonly is set to 0 if the file was opened for reading and
................................................................................
** On success, a handle for a previously open file at *id is
** 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
){
  int h;
  unixFile *pFile = (unixFile*)id;
  assert( pFile!=0 );
................................................................................
  }
#ifdef FD_CLOEXEC
  fcntl(h, F_SETFD, fcntl(h, F_GETFD, 0) | FD_CLOEXEC);
#endif
  OSTRACE3("OPENDIR %-3d %s\n", h, zDirname);
  return SQLITE_OK;
}


/*
** Check that a given pathname is a directory and is writable 
**
*/
int sqlite3UnixIsDirWritable(char *zBuf){
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
................................................................................
    }else{
      return SQLITE_FULL;
    }
  }
  return SQLITE_OK;
}

/*
** Move the read/write pointer in a file.
*/
static int unixSeek(OsFile *id, i64 offset){
  assert( id );
#ifdef SQLITE_TEST
  if( offset ) SimulateDiskfullError(return SQLITE_FULL);
#endif
  ((unixFile*)id)->offset = offset;
  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.
*/
int sqlite3_sync_count = 0;
int sqlite3_fullsync_count = 0;
................................................................................
** has been created by fsync-ing the directory that contains the file.
** 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(sqlite3_file *id, int dataOnly){
  int rc;
  unixFile *pFile = (unixFile*)id;




  assert( pFile );
  OSTRACE2("SYNC    %-3d\n", pFile->h);
  rc = full_fsync(pFile->h, pFile->fullSync, dataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
    return SQLITE_IOERR_FSYNC;
  }
  if( pFile->dirfd>=0 ){
    OSTRACE4("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
            HAVE_FULLFSYNC, pFile->fullSync);
#ifndef SQLITE_DISABLE_DIRSYNC
    /* The directory sync is only attempted if full_fsync is
    ** turned off or unavailable.  If a full_fsync occurred above,
    ** then the directory sync is superfluous.
    */
    if( (!HAVE_FULLFSYNC || !pFile->fullSync) && full_fsync(pFile->dirfd,0,0) ){
       /*
       ** We have received multiple reports of fsync() returning
       ** errors when applied to directories on certain file systems.
       ** A failed directory sync is not a big deal.  So it seems
       ** better to ignore the error.  Ticket #1657
       */
       /* return SQLITE_IOERR; */
................................................................................
  sqlite3_free(id);
  *pId = 0;
  return SQLITE_OK;
}

#endif /* SQLITE_ENABLE_LOCKING_STYLE */


/*
** 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;
}


/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.
**
** SQLite code assumes this function cannot fail. It also assumes that
................................................................................
** a database and it's journal file) that the sector size will be the
** same for both.
*/
static int unixSectorSize(sqlite3_file *id){
  return SQLITE_DEFAULT_SECTOR_SIZE;
}




static int unixDeviceCharacteristics(sqlite3_file *id){
  return 0;
}

static int unixBreakLock(sqlite3_file *id){
  assert(!"TODO: unixBreakLock()");
  return 0;
}









/*
** This vector defines all the methods that can operate on an OsFile
** for unix.
*/
static const sqlite3_io_methods sqlite3UnixIoMethod = {
  1,                        /* iVersion */
................................................................................
  unixTruncate,
  unixSync,
  unixFileSize,
  unixLock,
  unixUnlock,
  unixCheckReservedLock,
  unixBreakLock,

  unixSectorSize,
  unixDeviceCharacteristics
};

#ifdef SQLITE_ENABLE_LOCKING_STYLE
/*
 ** This vector defines all the methods that can operate on an OsFile
................................................................................
*/
static int unixDelete(void *pNotUsed, const char *zPath){
  SimulateIOError(return SQLITE_IOERR_DELETE);
  unlink(zPath);
  return SQLITE_OK;
}











static int unixAccess(void *pNotUsed, const char *zPath, int flags){
  int amode;
  switch( flags ){
    case SQLITE_ACCESS_EXISTS:
      amode = F_OK;
      break;
    case SQLITE_ACCESS_READWRITE:
................................................................................
  #define unixDlOpen  0
  #define unixDlError 0
  #define unixDlSym   0
  #define unixDlClose 0
#endif

/*
** Both arguments are integers. This macro returns the lowest of the 
** two arguments. 
*/
#define MIN(x,y) ((x)>(y)?(y):(x))

/*
** 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 unixRandomness(void *pNotUsed, int nBuf, 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.
................................................................................
#if !defined(SQLITE_TEST)
  {
    int pid, fd;
    fd = open("/dev/urandom", O_RDONLY);
    if( fd<0 ){
      time_t t;
      time(&t);
      memcpy(zBuf, &t, MIN(nBuf, sizeof(t)));
      if( (nBuf-sizeof(t))>0 ){
        pid = getpid();
        memcpy(&zBuf[sizeof(t)], &pid, MIN(nBuf-sizeof(t), sizeof(pid)));
      }
    }else{
      read(fd, zBuf, nBuf);
      close(fd);
    }
  }
#endif
  return SQLITE_OK;

  struct lockInfo *pLock;   /* Info about locks on this inode */
#ifdef SQLITE_ENABLE_LOCKING_STYLE
  void *lockingContext;     /* Locking style specific state */
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
  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 */

  int dirfd;                /* File descriptor for the directory */
  i64 offset;               /* Seek offset */
#ifdef SQLITE_UNIX_THREADS
  pthread_t tid;            /* The thread that "owns" this OsFile */
#endif
};

................................................................................
/*
** Return TRUE if the named file exists.
*/
int sqlite3UnixFileExists(const char *zFilename){
  return access(zFilename, 0)==0;
}









/*
** 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
** and *pReadonly is set to 0 if the file was opened for reading and
................................................................................
** On success, a handle for a previously open file at *id is
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
#if 0
static int unixOpenDirectory(
  OsFile *id,
  const char *zDirname
){
  int h;
  unixFile *pFile = (unixFile*)id;
  assert( pFile!=0 );
................................................................................
  }
#ifdef FD_CLOEXEC
  fcntl(h, F_SETFD, fcntl(h, F_GETFD, 0) | FD_CLOEXEC);
#endif
  OSTRACE3("OPENDIR %-3d %s\n", h, zDirname);
  return SQLITE_OK;
}
#endif

/*
** Check that a given pathname is a directory and is writable 
**
*/
int sqlite3UnixIsDirWritable(char *zBuf){
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
................................................................................
    }else{
      return SQLITE_FULL;
    }
  }
  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.
*/
int sqlite3_sync_count = 0;
int sqlite3_fullsync_count = 0;
................................................................................
** has been created by fsync-ing the directory that contains the file.
** 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(sqlite3_file *id, int flags){
  int rc;
  unixFile *pFile = (unixFile*)id;

  int isDataOnly = (flags & SQLITE_SYNC_DATAONLY);
  int isFullsync = (flags & SQLITE_SYNC_FULL);

  assert( pFile );
  OSTRACE2("SYNC    %-3d\n", pFile->h);
  rc = full_fsync(pFile->h, isFullsync, isDataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
    return SQLITE_IOERR_FSYNC;
  }
  if( pFile->dirfd>=0 ){
    OSTRACE4("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
            HAVE_FULLFSYNC, isFullsync);
#ifndef SQLITE_DISABLE_DIRSYNC
    /* The directory sync is only attempted if full_fsync is
    ** turned off or unavailable.  If a full_fsync occurred above,
    ** then the directory sync is superfluous.
    */
    if( (!HAVE_FULLFSYNC || !isFullsync) && full_fsync(pFile->dirfd,0,0) ){
       /*
       ** We have received multiple reports of fsync() returning
       ** errors when applied to directories on certain file systems.
       ** A failed directory sync is not a big deal.  So it seems
       ** better to ignore the error.  Ticket #1657
       */
       /* return SQLITE_IOERR; */
................................................................................
  sqlite3_free(id);
  *pId = 0;
  return SQLITE_OK;
}

#endif /* SQLITE_ENABLE_LOCKING_STYLE */

#if 0
/*
** 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;
}








#endif

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.
**
** SQLite code assumes this function cannot fail. It also assumes that
................................................................................
** a database and it's journal file) that the sector size will be the
** same for both.
*/
static int unixSectorSize(sqlite3_file *id){
  return SQLITE_DEFAULT_SECTOR_SIZE;
}

/*
** Return the device characteristics for the file. This is always 0.
*/
static int unixDeviceCharacteristics(sqlite3_file *id){
  return 0;
}

static int unixBreakLock(sqlite3_file *id){
  assert(!"TODO: unixBreakLock()");
  return 0;
}

/*
** Return an integer that indices the type of lock currently held
** by this handle.  (Used for testing and analysis only.)
*/
static int unixLockState(sqlite3_file *id){
  return ((unixFile*)id)->locktype;
}

/*
** This vector defines all the methods that can operate on an OsFile
** for unix.
*/
static const sqlite3_io_methods sqlite3UnixIoMethod = {
  1,                        /* iVersion */
................................................................................
  unixTruncate,
  unixSync,
  unixFileSize,
  unixLock,
  unixUnlock,
  unixCheckReservedLock,
  unixBreakLock,
  unixLockState,
  unixSectorSize,
  unixDeviceCharacteristics
};

#ifdef SQLITE_ENABLE_LOCKING_STYLE
/*
 ** This vector defines all the methods that can operate on an OsFile
................................................................................
*/
static int unixDelete(void *pNotUsed, const char *zPath){
  SimulateIOError(return SQLITE_IOERR_DELETE);
  unlink(zPath);
  return SQLITE_OK;
}

/*
** Test the existance of or access permissions of file zPath. The
** test performed depends on the value of flags:
**
**     SQLITE_ACCESS_EXISTS: Return 1 if the file exists
**     SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable.
**     SQLITE_ACCESS_READONLY: Return 1 if the file is readable.
**
** Otherwise return 0.
*/
static int unixAccess(void *pNotUsed, const char *zPath, int flags){
  int amode;
  switch( flags ){
    case SQLITE_ACCESS_EXISTS:
      amode = F_OK;
      break;
    case SQLITE_ACCESS_READWRITE:
................................................................................
  #define unixDlOpen  0
  #define unixDlError 0
  #define unixDlSym   0
  #define unixDlClose 0
#endif

/*
** Write nBuf bytes of random data to the supplied buffer zBuf.

*/







static int unixRandomness(void *pNotUsed, int nBuf, char *zBuf){

  assert(nBuf>=(sizeof(time_t)+sizeof(int)));

  /* 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.
................................................................................
#if !defined(SQLITE_TEST)
  {
    int pid, fd;
    fd = open("/dev/urandom", O_RDONLY);
    if( fd<0 ){
      time_t t;
      time(&t);
      memcpy(zBuf, &t, sizeof(t));

      pid = getpid();
      memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));

    }else{
      read(fd, zBuf, nBuf);
      close(fd);
    }
  }
#endif
  return SQLITE_OK;

** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.228 2007/08/17 15:53:37 danielk1977 Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
  int (*xTruncate)(sqlite3_file*, sqlite_int64 size);
  int (*xSync)(sqlite3_file*, int flags);
  int (*xFileSize)(sqlite3_file*, sqlite_int64 *pSize);
  int (*xLock)(sqlite3_file*, int);
  int (*xUnlock)(sqlite3_file*, int);
  int (*xCheckReservedLock)(sqlite3_file*);
  int (*xBreakLock)(sqlite3_file*);

  int (*xSectorSize)(sqlite3_file*);
  int (*xDeviceCharacteristics)(sqlite3_file*);
  /* Additional methods may be added in future releases */
};

/*
** CAPI3REF: Mutex Handle

** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.229 2007/08/17 16:50:38 danielk1977 Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
  int (*xTruncate)(sqlite3_file*, sqlite_int64 size);
  int (*xSync)(sqlite3_file*, int flags);
  int (*xFileSize)(sqlite3_file*, sqlite_int64 *pSize);
  int (*xLock)(sqlite3_file*, int);
  int (*xUnlock)(sqlite3_file*, int);
  int (*xCheckReservedLock)(sqlite3_file*);
  int (*xBreakLock)(sqlite3_file*);
  int (*xLockState)(sqlite3_file *);
  int (*xSectorSize)(sqlite3_file*);
  int (*xDeviceCharacteristics)(sqlite3_file*);
  /* Additional methods may be added in future releases */
};

/*
** CAPI3REF: Mutex Handle