** 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 1.399 2007/08/17 01:14:38 drh 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"

................................................................................
*/
int sqlite3BtreeOpen(
  const char *zFilename,  /* Name of the file containing the BTree database */
  sqlite3 *pSqlite,       /* Associated database handle */
  Btree **ppBtree,        /* Pointer to new Btree object written here */
  int flags               /* Options */
){

  BtShared *pBt = 0;      /* Shared part of btree structure */
  Btree *p;               /* Handle to return */
  int rc = SQLITE_OK;
  int nReserve;
  unsigned char zDbHeader[100];

  /* Set the variable isMemdb to true for an in-memory database, or 
................................................................................
    assert( sizeof(Pgno)==4 );
  
    pBt = sqlite3MallocZero( sizeof(*pBt) );
    if( pBt==0 ){
      rc = SQLITE_NOMEM;
      goto btree_open_out;
    }
    rc = sqlite3PagerOpen(&pBt->pPager, zFilename, EXTRA_SIZE, flags);
    if( rc==SQLITE_OK ){
      rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
    }
    if( rc!=SQLITE_OK ){
      goto btree_open_out;
    }
    p->pBt = pBt;

** 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"

................................................................................
*/
int sqlite3BtreeOpen(
  const char *zFilename,  /* Name of the file containing the BTree database */
  sqlite3 *pSqlite,       /* Associated database handle */
  Btree **ppBtree,        /* Pointer to new Btree object written here */
  int flags               /* Options */
){
  sqlite3_vfs *pVfs = (pSqlite?pSqlite->pVfs:sqlite3_find_vfs(0));
  BtShared *pBt = 0;      /* Shared part of btree structure */
  Btree *p;               /* Handle to return */
  int rc = SQLITE_OK;
  int nReserve;
  unsigned char zDbHeader[100];

  /* Set the variable isMemdb to true for an in-memory database, or 
................................................................................
    assert( sizeof(Pgno)==4 );
  
    pBt = sqlite3MallocZero( sizeof(*pBt) );
    if( pBt==0 ){
      rc = SQLITE_NOMEM;
      goto btree_open_out;
    }
    rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename, EXTRA_SIZE, flags);
    if( rc==SQLITE_OK ){
      rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
    }
    if( rc!=SQLITE_OK ){
      goto btree_open_out;
    }
    p->pBt = pBt;

*/
int sqlite3_load_extension(
  sqlite3 *db,          /* Load the extension into this database connection */
  const char *zFile,    /* Name of the shared library containing extension */
  const char *zProc,    /* Entry point.  Use "sqlite3_extension_init" if 0 */
  char **pzErrMsg       /* Put error message here if not 0 */
){

  void *handle;
  int (*xInit)(sqlite3*,char**,const sqlite3_api_routines*);
  char *zErrmsg = 0;
  void **aHandle;

  /* Ticket #1863.  To avoid a creating security problems for older
  ** applications that relink against newer versions of SQLite, the
................................................................................
    return SQLITE_ERROR;
  }

  if( zProc==0 ){
    zProc = "sqlite3_extension_init";
  }

  handle = sqlite3OsDlopen(zFile);
  if( handle==0 ){
    if( pzErrMsg ){
      *pzErrMsg = sqlite3_mprintf("unable to open shared library [%s]", zFile);
    }
    return SQLITE_ERROR;
  }
  xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
                   sqlite3OsDlsym(handle, zProc);
  if( xInit==0 ){
    if( pzErrMsg ){
       *pzErrMsg = sqlite3_mprintf("no entry point [%s] in shared library [%s]",
                                   zProc, zFile);
    }
    sqlite3OsDlclose(handle);
    return SQLITE_ERROR;
  }else if( xInit(db, &zErrmsg, &sqlite3_apis) ){
    if( pzErrMsg ){
      *pzErrMsg = sqlite3_mprintf("error during initialization: %s", zErrmsg);
    }
    sqlite3_free(zErrmsg);
    sqlite3OsDlclose(handle);
    return SQLITE_ERROR;
  }

  /* Append the new shared library handle to the db->aExtension array. */
  db->nExtension++;
  aHandle = sqlite3DbMallocZero(db, sizeof(handle)*db->nExtension);
  if( aHandle==0 ){
................................................................................
/*
** Call this routine when the database connection is closing in order
** to clean up loaded extensions
*/
void sqlite3CloseExtensions(sqlite3 *db){
  int i;
  for(i=0; i<db->nExtension; i++){
    sqlite3OsDlclose(db->aExtension[i]);
  }
  sqlite3_free(db->aExtension);
}

/*
** Enable or disable extension loading.  Extension loading is disabled by
** default so as not to open security holes in older applications.
................................................................................
/*
** Register a statically linked extension that is automatically
** loaded by every new database connection.
*/
int sqlite3_auto_extension(void *xInit){
  int i;
  int rc = SQLITE_OK;
  sqlite3OsEnterMutex();

  for(i=0; i<nAutoExtension; i++){
    if( aAutoExtension[i]==xInit ) break;
  }
  if( i==nAutoExtension ){
    nAutoExtension++;
    aAutoExtension = sqlite3_realloc( aAutoExtension,
                                     nAutoExtension*sizeof(aAutoExtension[0]) );
    if( aAutoExtension==0 ){
      nAutoExtension = 0;
      rc = SQLITE_NOMEM;
    }else{
      aAutoExtension[nAutoExtension-1] = xInit;
    }
  }
  sqlite3OsLeaveMutex();
  assert( (rc&0xff)==rc );
  return rc;
}

/*
** Reset the automatic extension loading mechanism.
*/
void sqlite3_reset_auto_extension(void){
  sqlite3OsEnterMutex();

  sqlite3_free(aAutoExtension);
  aAutoExtension = 0;
  nAutoExtension = 0;
  sqlite3OsLeaveMutex();
}

/*
** Load all automatic extensions.
*/
int sqlite3AutoLoadExtensions(sqlite3 *db){
  int i;
................................................................................

  if( nAutoExtension==0 ){
    /* Common case: early out without every having to acquire a mutex */
    return SQLITE_OK;
  }
  for(i=0; go; i++){
    char *zErrmsg = 0;
    sqlite3OsEnterMutex();

    if( i>=nAutoExtension ){
      xInit = 0;
      go = 0;
    }else{
      xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
              aAutoExtension[i];
    }
    sqlite3OsLeaveMutex();
    if( xInit && xInit(db, &zErrmsg, &sqlite3_apis) ){
      sqlite3Error(db, SQLITE_ERROR,
            "automatic extension loading failed: %s", zErrmsg);
      go = 0;
      rc = SQLITE_ERROR;
    }
  }
  return rc;
}

#endif /* SQLITE_OMIT_LOAD_EXTENSION */

*/
int sqlite3_load_extension(
  sqlite3 *db,          /* Load the extension into this database connection */
  const char *zFile,    /* Name of the shared library containing extension */
  const char *zProc,    /* Entry point.  Use "sqlite3_extension_init" if 0 */
  char **pzErrMsg       /* Put error message here if not 0 */
){
  sqlite3_vfs *pVfs = db->pVfs;
  void *handle;
  int (*xInit)(sqlite3*,char**,const sqlite3_api_routines*);
  char *zErrmsg = 0;
  void **aHandle;

  /* Ticket #1863.  To avoid a creating security problems for older
  ** applications that relink against newer versions of SQLite, the
................................................................................
    return SQLITE_ERROR;
  }

  if( zProc==0 ){
    zProc = "sqlite3_extension_init";
  }

  handle = sqlite3OsDlOpen(pVfs, zFile);
  if( handle==0 ){
    if( pzErrMsg ){
      *pzErrMsg = sqlite3_mprintf("unable to open shared library [%s]", zFile);
    }
    return SQLITE_ERROR;
  }
  xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
                   sqlite3OsDlSym(pVfs, handle, zProc);
  if( xInit==0 ){
    if( pzErrMsg ){
       *pzErrMsg = sqlite3_mprintf("no entry point [%s] in shared library [%s]",
                                   zProc, zFile);
    }
    sqlite3OsDlClose(pVfs, handle);
    return SQLITE_ERROR;
  }else if( xInit(db, &zErrmsg, &sqlite3_apis) ){
    if( pzErrMsg ){
      *pzErrMsg = sqlite3_mprintf("error during initialization: %s", zErrmsg);
    }
    sqlite3_free(zErrmsg);
    sqlite3OsDlClose(pVfs, handle);
    return SQLITE_ERROR;
  }

  /* Append the new shared library handle to the db->aExtension array. */
  db->nExtension++;
  aHandle = sqlite3DbMallocZero(db, sizeof(handle)*db->nExtension);
  if( aHandle==0 ){
................................................................................
/*
** Call this routine when the database connection is closing in order
** to clean up loaded extensions
*/
void sqlite3CloseExtensions(sqlite3 *db){
  int i;
  for(i=0; i<db->nExtension; i++){
    sqlite3OsDlClose(db->pVfs, db->aExtension[i]);
  }
  sqlite3_free(db->aExtension);
}

/*
** Enable or disable extension loading.  Extension loading is disabled by
** default so as not to open security holes in older applications.
................................................................................
/*
** Register a statically linked extension that is automatically
** loaded by every new database connection.
*/
int sqlite3_auto_extension(void *xInit){
  int i;
  int rc = SQLITE_OK;
  sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL);
  sqlite3_mutex_enter(mutex);
  for(i=0; i<nAutoExtension; i++){
    if( aAutoExtension[i]==xInit ) break;
  }
  if( i==nAutoExtension ){
    int nByte = (++nAutoExtension)*sizeof(aAutoExtension[0]);
    aAutoExtension = sqlite3_realloc(aAutoExtension, nByte);

    if( aAutoExtension==0 ){
      nAutoExtension = 0;
      rc = SQLITE_NOMEM;
    }else{
      aAutoExtension[nAutoExtension-1] = xInit;
    }
  }
  sqlite3_mutex_leave(mutex);
  assert( (rc&0xff)==rc );
  return rc;
}

/*
** Reset the automatic extension loading mechanism.
*/
void sqlite3_reset_auto_extension(void){
  sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL);
  sqlite3_mutex_enter(mutex);
  sqlite3_free(aAutoExtension);
  aAutoExtension = 0;
  nAutoExtension = 0;
  sqlite3_mutex_leave(mutex);
}

/*
** Load all automatic extensions.
*/
int sqlite3AutoLoadExtensions(sqlite3 *db){
  int i;
................................................................................

  if( nAutoExtension==0 ){
    /* Common case: early out without every having to acquire a mutex */
    return SQLITE_OK;
  }
  for(i=0; go; i++){
    char *zErrmsg = 0;
    sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL);
    sqlite3_mutex_enter(mutex);
    if( i>=nAutoExtension ){
      xInit = 0;
      go = 0;
    }else{
      xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
              aAutoExtension[i];
    }
    sqlite3_mutex_leave(mutex);
    if( xInit && xInit(db, &zErrmsg, &sqlite3_apis) ){
      sqlite3Error(db, SQLITE_ERROR,
            "automatic extension loading failed: %s", zErrmsg);
      go = 0;
      rc = SQLITE_ERROR;
    }
  }
  return rc;
}

#endif /* SQLITE_OMIT_LOAD_EXTENSION */

**
*************************************************************************
** 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 1.383 2007/08/17 01:14:38 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** The version of the library
................................................................................
){
#if OS_WIN || (defined(HAVE_USLEEP) && HAVE_USLEEP)
  static const u8 delays[] =
     { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
  static const u8 totals[] =
     { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
# define NDELAY (sizeof(delays)/sizeof(delays[0]))
  int timeout = ((sqlite3 *)ptr)->busyTimeout;

  int delay, prior;

  assert( count>=0 );
  if( count < NDELAY ){
    delay = delays[count];
    prior = totals[count];
  }else{
................................................................................
    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);
................................................................................
  sqlite3 *db;
  int rc;
  CollSeq *pColl;

  /* Allocate the sqlite data structure */
  db = sqlite3MallocZero( sizeof(sqlite3) );
  if( db==0 ) goto opendb_out;

  db->errMask = 0xff;
  db->priorNewRowid = 0;
  db->magic = SQLITE_MAGIC_BUSY;
  db->nDb = 2;
  db->aDb = db->aDbStatic;
  db->autoCommit = 1;
  db->flags |= SQLITE_ShortColNames
................................................................................
  return rc;
}

/*
** Sleep for a little while.  Return the amount of time slept.
*/
int sqlite3_sleep(int ms){


  return sqlite3OsSleep(ms);
}

/*
** Enable or disable the extended result codes.
*/
int sqlite3_extended_result_codes(sqlite3 *db, int onoff){
  db->errMask = onoff ? 0xffffffff : 0xff;
  return SQLITE_OK;
}

**
*************************************************************************
** 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 1.384 2007/08/17 15:53:36 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** The version of the library
................................................................................
){
#if OS_WIN || (defined(HAVE_USLEEP) && HAVE_USLEEP)
  static const u8 delays[] =
     { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
  static const u8 totals[] =
     { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
# define NDELAY (sizeof(delays)/sizeof(delays[0]))
  sqlite3 *db = (sqlite3 *)ptr;
  int timeout = db->busyTimeout;
  int delay, prior;

  assert( count>=0 );
  if( count < NDELAY ){
    delay = delays[count];
    prior = totals[count];
  }else{
................................................................................
    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(db->pVfs, delay);
  return 1;
#else
  int timeout = ((sqlite3 *)ptr)->busyTimeout;
  if( (count+1)*1000 > timeout ){
    return 0;
  }
  sqlite3OsSleep(1000);
................................................................................
  sqlite3 *db;
  int rc;
  CollSeq *pColl;

  /* Allocate the sqlite data structure */
  db = sqlite3MallocZero( sizeof(sqlite3) );
  if( db==0 ) goto opendb_out;
  db->pVfs = sqlite3_find_vfs(0);
  db->errMask = 0xff;
  db->priorNewRowid = 0;
  db->magic = SQLITE_MAGIC_BUSY;
  db->nDb = 2;
  db->aDb = db->aDbStatic;
  db->autoCommit = 1;
  db->flags |= SQLITE_ShortColNames
................................................................................
  return rc;
}

/*
** Sleep for a little while.  Return the amount of time slept.
*/
int sqlite3_sleep(int ms){
  sqlite3_vfs *pVfs;
  pVfs = sqlite3_find_vfs(0);
  return sqlite3OsSleep(pVfs, 1000*ms);
}

/*
** Enable or disable the extended result codes.
*/
int sqlite3_extended_result_codes(sqlite3 *db, int onoff){
  db->errMask = onoff ? 0xffffffff : 0xff;
  return SQLITE_OK;
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.  
**
** $Id: mem1.c,v 1.5 2007/08/16 19:40:17 drh Exp $
*/

/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
................................................................................
  unsigned nOld;
  sqlite3_uint64 *p;
  if( pPrior==0 ){
    return sqlite3_malloc(nBytes);
  }
  if( nBytes==0 ){
    sqlite3_free(pPrior);
    return;
  }
  p = pPrior;
  p--;
  nOld = (unsigned int)p[0];
  assert( mem.mutex!=0 );
  sqlite3_mutex_enter(mem.mutex);
  if( mem.nowUsed+nBytes-nOld>=mem.alarmThreshold ){

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.  
**
** $Id: mem1.c,v 1.6 2007/08/17 15:53:36 danielk1977 Exp $
*/

/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
................................................................................
  unsigned nOld;
  sqlite3_uint64 *p;
  if( pPrior==0 ){
    return sqlite3_malloc(nBytes);
  }
  if( nBytes==0 ){
    sqlite3_free(pPrior);
    return 0;
  }
  p = pPrior;
  p--;
  nOld = (unsigned int)p[0];
  assert( mem.mutex!=0 );
  sqlite3_mutex_enter(mem.mutex);
  if( mem.nowUsed+nBytes-nOld>=mem.alarmThreshold ){

/*
** The following routines are convenience wrappers around methods
** of the sqlite3_file 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(sqlite3_file **pId){
  int rc = SQLITE_OK;
  sqlite3_file *id;
  if( pId!=0 && (id = *pId)!=0 ){
    rc = id->pMethods->xClose(id);
    if( rc==SQLITE_OK ){
      *pId = 0;
    }
  }
  return rc;
}
int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){
  return id->pMethods->xRead(id, pBuf, amt, offset);
}
int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
  return id->pMethods->xWrite(id, pBuf, amt, offset);
}
................................................................................
  }
  int sqlite3OsLockState(sqlite3_file *id){
    /* return id->pMethods->xLockState(id); */
    return 0;
  }
#endif

#ifdef SQLITE_ENABLE_REDEF_IO






































































/*
** A function to return a pointer to the virtual function table.
** This routine really does not accomplish very much since the
** virtual function table is a global variable and anybody who
** can call this function can just as easily access the variable
** for themselves.  Nevertheless, we include this routine for
** backwards compatibility with an earlier redefinable I/O
** interface design.

*/
struct sqlite3OsVtbl *sqlite3_os_switch(void){



  return &sqlite3Os;
}
#endif

/*
** The following routines are convenience wrappers around methods
** of the sqlite3_file 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(sqlite3_file *pId){
  if( !pId->pMethods ) return SQLITE_OK;


  return pId->pMethods->xClose(pId);





}
int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){
  return id->pMethods->xRead(id, pBuf, amt, offset);
}
int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
  return id->pMethods->xWrite(id, pBuf, amt, offset);
}
................................................................................
  }
  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 flags, 
  int *pFlagsOut
){
  return pVfs->xOpen(pVfs->pAppData, zPath, pFile, flags, pFlagsOut);
}
int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath){
  return pVfs->xDelete(pVfs->pAppData, zPath);
}
int sqlite3OsAccess(sqlite3_vfs *pVfs, const char *zPath, int flags){
  return pVfs->xAccess(pVfs->pAppData, zPath, flags);
}
int sqlite3OsGetTempName(sqlite3_vfs *pVfs, char *zBufOut){
  return pVfs->xGetTempName(pVfs->pAppData, zBufOut);
}
int sqlite3OsFullPathname(sqlite3_vfs *pVfs, const char *zPath, char *zPathOut){
  return pVfs->xFullPathname(pVfs->pAppData, zPath, zPathOut);
}
void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
  return pVfs->xDlOpen(pVfs->pAppData, zPath);
}
void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
  pVfs->xDlError(pVfs->pAppData, nByte, zBufOut);
}
void *sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol){
  return pVfs->xDlSym(pHandle, zSymbol);
}
void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
  pVfs->xDlClose(pHandle);
}
int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
  return pVfs->xRandomness(pVfs->pAppData, nByte, zBufOut);
}
int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
  return pVfs->xSleep(pVfs->pAppData, nMicro);
}
int sqlite3OsCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
  return pVfs->xCurrentTime(pVfs->pAppData, pTimeOut);
}

int sqlite3OsOpenMalloc(
  sqlite3_vfs *pVfs, 
  const char *zFile, 
  sqlite3_file **ppFile, 
  int flags
){
  int rc = SQLITE_NOMEM;
  sqlite3_file *pFile;
  pFile = (sqlite3_file *)sqlite3_malloc(pVfs->szOsFile);
  if( pFile ){
    rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, 0);
    if( rc!=SQLITE_OK ){
      sqlite3_free(pFile);
    }else{
      *ppFile = pFile;
    }
  }
  return rc;
}
int sqlite3OsCloseFree(sqlite3_file *pFile){
  int rc = SQLITE_OK;
  if( pFile ){
    rc = sqlite3OsClose(pFile);
    sqlite3_free(pFile);
  }
  return rc;
}

/* 







** Default vfs implementation. Defined by the various os_X.c implementations.
*/

extern sqlite3_vfs sqlite3DefaultVfs;

sqlite3_vfs *sqlite3_find_vfs(const char *zVfs){
  return &sqlite3DefaultVfs;
}

** 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



/*
** Define the interfaces for Unix, Windows, and OS/2.
*/
#if OS_UNIX
#define sqlite3OsOpenReadWrite      sqlite3UnixOpenReadWrite
#define sqlite3OsOpenExclusive      sqlite3UnixOpenExclusive
#define sqlite3OsOpenReadOnly       sqlite3UnixOpenReadOnly
................................................................................
#define sqlite3OsFree               sqlite3GenericFree
#define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
#define sqlite3OsDlopen             sqlite3Os2Dlopen
#define sqlite3OsDlsym              sqlite3Os2Dlsym
#define sqlite3OsDlclose            sqlite3Os2Dlclose
#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.
................................................................................
#define PENDING_BYTE sqlite3_pending_byte
#endif

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

/*
** Prototypes for operating system interface routines.
*/
int sqlite3OsClose(sqlite3_file**);
int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset);
int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset);
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);

























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*);
................................................................................
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*);


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

/*
................................................................................
    IF_DISKIO( sqlite3OsTempFileName ),
    sqlite3OsRandomSeed,
    sqlite3OsSleep,
    sqlite3OsCurrentTime,
    sqlite3OsEnterMutex,
    sqlite3OsLeaveMutex,
    sqlite3OsInMutex,
    sqlite3OsThreadSpecificData,
    sqlite3OsMalloc,
    sqlite3OsRealloc,
    sqlite3OsFree,
    sqlite3OsAllocationSize,
    IF_DLOPEN( sqlite3OsDlopen ),
    IF_DLOPEN( sqlite3OsDlsym ),
    IF_DLOPEN( sqlite3OsDlclose ),

** 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 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.
................................................................................
#define PENDING_BYTE sqlite3_pending_byte
#endif

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

/* 
** Functions for accessing sqlite3_file methods 
*/
int sqlite3OsClose(sqlite3_file*);
int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset);
int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset);
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 *);
int sqlite3OsDelete(sqlite3_vfs *, const char *);
int sqlite3OsAccess(sqlite3_vfs *, const char *, int);
int sqlite3OsGetTempName(sqlite3_vfs *, char *);
int sqlite3OsFullPathname(sqlite3_vfs *, const char *, char *);
void *sqlite3OsDlOpen(sqlite3_vfs *, const char *);
void sqlite3OsDlError(sqlite3_vfs *, int, char *);
void *sqlite3OsDlSym(sqlite3_vfs *, void *, const char *);
void sqlite3OsDlClose(sqlite3_vfs *, void *);
int sqlite3OsRandomness(sqlite3_vfs *, int, char *);
int sqlite3OsSleep(sqlite3_vfs *, int);
int sqlite3OsCurrentTime(sqlite3_vfs *, double*);

/*
** 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*);
................................................................................
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_DISKIO( sqlite3OsTempFileName ),
    sqlite3OsRandomSeed,
    sqlite3OsSleep,
    sqlite3OsCurrentTime,
    sqlite3OsEnterMutex,
    sqlite3OsLeaveMutex,
    sqlite3OsInMutex,
    0,
    sqlite3OsMalloc,
    sqlite3OsRealloc,
    sqlite3OsFree,
    sqlite3OsAllocationSize,
    IF_DLOPEN( sqlite3OsDlopen ),
    IF_DLOPEN( sqlite3OsDlsym ),
    IF_DLOPEN( sqlite3OsDlclose ),

/*
** Default permissions when creating a new file
*/
#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;
................................................................................
        afpLockingStyle,             /* use afp locks */
        flockLockingStyle,           /* use flock() */
        dotlockLockingStyle,         /* use <file>.lock files */
        noLockingStyle,              /* useful for read-only file system */
        unsupportedLockingStyle      /* indicates unsupported file system */
} sqlite3LockingStyle;
#endif /* SQLITE_ENABLE_LOCKING_STYLE */








#ifdef SQLITE_UNIX_THREADS
/*
** This variable records whether or not threads can override each others
** locks.
**
**    0:  No.  Threads cannot override each others locks.
................................................................................
}
#endif /* SQLITE_UNIX_THREADS */

/*
** Release a lockInfo structure previously allocated by findLockInfo().
*/
static void releaseLockInfo(struct lockInfo *pLock){
  assert( sqlite3OsInMutex(1) );
  if (pLock == NULL)
    return;
  pLock->nRef--;
  if( pLock->nRef==0 ){
    sqlite3HashInsert(&lockHash, &pLock->key, sizeof(pLock->key), 0);
    sqlite3_free(pLock);
  }
}

/*
** Release a openCnt structure previously allocated by findLockInfo().
*/
static void releaseOpenCnt(struct openCnt *pOpen){
  assert( sqlite3OsInMutex(1) );
  if (pOpen == NULL)
    return;
  pOpen->nRef--;
  if( pOpen->nRef==0 ){
    sqlite3HashInsert(&openHash, &pOpen->key, sizeof(pOpen->key), 0);
    free(pOpen->aPending);
    sqlite3_free(pOpen);
................................................................................
  struct openKey key2;
  struct stat statbuf;
  struct lockInfo *pLock;
  struct openCnt *pOpen;
  rc = fstat(fd, &statbuf);
  if( rc!=0 ) return 1;

  assert( sqlite3OsInMutex(1) );
  memset(&key1, 0, sizeof(key1));
  key1.dev = statbuf.st_dev;
  key1.ino = statbuf.st_ino;
#ifdef SQLITE_UNIX_THREADS
  if( threadsOverrideEachOthersLocks<0 ){
    testThreadLockingBehavior(fd);
  }
................................................................................
** and *pReadonly is set to 0 if the file was opened for reading and
** writing or 1 if the file was opened read-only.  The function returns
** SQLITE_OK.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id and *pReadonly unchanged.
*/

int sqlite3UnixOpenReadWrite(
  const char *zFilename,
  sqlite3_file **pId,
  int *pReadonly
){
  int h;
  
................................................................................
  if( h<0 ){
    return SQLITE_CANTOPEN;
  }
  return CRASH_TEST_OVERRIDE(
    zFilename, pId, allocateUnixFile(h, pId, zFilename, 0)
  );
}


/*
** 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.
**
................................................................................
#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;
}

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at least SQLITE_TEMPNAME_SIZE characters.
*/
int sqlite3UnixTempFileName(char *zBuf){
  static const char *azDirs[] = {
     0,
     "/var/tmp",
     "/usr/tmp",
     "/tmp",
     ".",
  };
  static const unsigned char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  struct stat buf;
  const char *zDir = ".";
  azDirs[0] = sqlite3_temp_directory;
  for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
    if( azDirs[i]==0 ) continue;
    if( stat(azDirs[i], &buf) ) continue;
    if( !S_ISDIR(buf.st_mode) ) continue;
    if( access(azDirs[i], 07) ) continue;
    zDir = azDirs[i];
    break;
  }
  do{
    sqlite3_snprintf(SQLITE_TEMPNAME_SIZE, zBuf, "%s/"TEMP_FILE_PREFIX, zDir);
    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;
  }while( access(zBuf,0)==0 );
  return SQLITE_OK; 
}

/*
** Check that a given pathname is a directory and is writable 
**
*/
int sqlite3UnixIsDirWritable(char *zBuf){
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
  struct stat buf;
................................................................................
** return zero.
*/
static int unixCheckReservedLock(sqlite3_file *id){
  int r = 0;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  sqlite3OsEnterMutex(); /* 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.
................................................................................
    lock.l_type = F_WRLCK;
    fcntl(pFile->h, F_GETLK, &lock);
    if( lock.l_type!=F_UNLCK ){
      r = 1;
    }
  }
  
  sqlite3OsLeaveMutex();
  OSTRACE3("TEST WR-LOCK %d %d\n", pFile->h, r);

  return r;
}

/*
** Lock the file with the lock specified by parameter locktype - one
................................................................................
  assert( pFile );
  OSTRACE7("LOCK    %d %s was %s(%s,%d) pid=%d\n", pFile->h,
      locktypeName(locktype), locktypeName(pFile->locktype),
      locktypeName(pLock->locktype), pLock->cnt , getpid());

  /* 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 ){
    OSTRACE3("LOCK    %d %s ok (already held)\n", pFile->h,
            locktypeName(locktype));
    return SQLITE_OK;
  }

................................................................................
  */
  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
  */
  sqlite3OsEnterMutex();

  /* Make sure the current thread owns the pFile.
  */
  rc = transferOwnership(pFile);
  if( rc!=SQLITE_OK ){
    sqlite3OsLeaveMutex();
    return rc;
  }
  pLock = pFile->pLock;

  /* If some thread using this PID has a lock via a different OsFile*
  ** handle that precludes the requested lock, return BUSY.
  */
................................................................................
    pLock->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;
    pLock->locktype = PENDING_LOCK;
  }

end_lock:
  sqlite3OsLeaveMutex();
  OSTRACE4("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
................................................................................
  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  if( CHECK_THREADID(pFile) ){
    return SQLITE_MISUSE;
  }
  sqlite3OsEnterMutex();
  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;
................................................................................
        close(pOpen->aPending[i]);
      }
      free(pOpen->aPending);
      pOpen->nPending = 0;
      pOpen->aPending = 0;
    }
  }
  sqlite3OsLeaveMutex();
  pFile->locktype = locktype;
  return rc;
}

/*
** Close a file.
*/
static int unixClose(sqlite3_file *id){
  unixFile *pFile = (unixFile *)id;
  if( !pFile ) return SQLITE_OK;
  unixUnlock(id, NO_LOCK);
  if( pFile->dirfd>=0 ) close(pFile->dirfd);
  pFile->dirfd = -1;
  sqlite3OsEnterMutex();

  if( pFile->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.
    */
................................................................................
  }else{
    /* There are no outstanding locks so we can close the file immediately */
    close(pFile->h);
  }
  releaseLockInfo(pFile->pLock);
  releaseOpenCnt(pFile->pOpen);

  sqlite3OsLeaveMutex();
  pFile->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", pFile->h);
  OpenCounter(-1);
  sqlite3_free(id);
  return SQLITE_OK;
}


#ifdef SQLITE_ENABLE_LOCKING_STYLE
#pragma mark AFP Support

................................................................................
  int gotPendingLock = 0;
  
  assert( pFile );
  OSTRACE5("LOCK    %d %s was %s pid=%d\n", pFile->h,
         locktypeName(locktype), locktypeName(pFile->locktype), getpid());  
  /* If there is already a lock of this type or more restrictive on the
    ** OsFile, do nothing. Don't use the afp_end_lock: exit path, as
    ** sqlite3OsEnterMutex() hasn't been called yet.
    */
  if( pFile->locktype>=locktype ){
    OSTRACE3("LOCK    %d %s ok (already held)\n", pFile->h,
           locktypeName(locktype));
    return SQLITE_OK;
  }

................................................................................
    */
  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
    */
  sqlite3OsEnterMutex();

  /* Make sure the current thread owns the pFile.
    */
  rc = transferOwnership(pFile);
  if( rc!=SQLITE_OK ){
    sqlite3OsLeaveMutex();
    return rc;
  }
    
  /* 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( rc==SQLITE_OK ){
    pFile->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;
  }
  
afp_end_lock:
    sqlite3OsLeaveMutex();
  OSTRACE4("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
................................................................................
  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  if( CHECK_THREADID(pFile) ){
    return SQLITE_MISUSE;
  }
  sqlite3OsEnterMutex();
  if( pFile->locktype>SHARED_LOCK ){
    if( locktype==SHARED_LOCK ){
      int failed = 0;

      /* unlock the exclusive range - then re-establish the shared lock */
      if (pFile->locktype==EXCLUSIVE_LOCK) {
        failed = _AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST, 
................................................................................
                               SHARED_FIRST + context->sharedLockByte, 1, 0);
    if (failed) {
      rc = SQLITE_IOERR_UNLOCK;  /* This should never happen */
    }
  }
  if (rc == SQLITE_OK)
    pFile->locktype = locktype;
  sqlite3OsLeaveMutex();
  return rc;
}

/*
 ** Close a file & cleanup AFP specific locking context 
 */
static int afpUnixClose(OsFile **pId) {
................................................................................
  unixFile *id = (unixFile*)*pId;
  
  if( !id ) return SQLITE_OK;
  flockUnixUnlock(*pId, NO_LOCK);
  
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  sqlite3OsEnterMutex();
  
  close(id->h);  
  sqlite3OsLeaveMutex();
  id->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  sqlite3_free(id);
  *pId = 0;
  return SQLITE_OK;
}
................................................................................
      sqlite3_free( ( (dotlockLockingContext *)
        id->lockingContext)->lockPath);
    sqlite3_free(id->lockingContext);
  }
  
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  sqlite3OsEnterMutex();
  
  close(id->h);
  
  sqlite3OsLeaveMutex();
  id->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  sqlite3_free(id);
  *pId = 0;
  return SQLITE_OK;
}
................................................................................
 */
static int nolockUnixClose(OsFile **pId) {
  unixFile *id = (unixFile*)*pId;
  
  if( !id ) return SQLITE_OK;
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  sqlite3OsEnterMutex();
  
  close(id->h);
  
  sqlite3OsLeaveMutex();
  id->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  sqlite3_free(id);
  *pId = 0;
  return SQLITE_OK;
}

#endif /* SQLITE_ENABLE_LOCKING_STYLE */

/*
** 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
** is no longer needed.
*/
char *sqlite3UnixFullPathname(const char *zRelative){
  char *zFull = 0;
  if( zRelative[0]=='/' ){
    sqlite3SetString(&zFull, zRelative, (char*)0);
  }else{
    char *zBuf = sqlite3_malloc(5000);
    if( zBuf==0 ){
      return 0;
    }
    zBuf[0] = 0;
    sqlite3SetString(&zFull, getcwd(zBuf, 5000), "/", zRelative,
                    (char*)0);
    sqlite3_free(zBuf);
  }

#if 0
  /*
  ** Remove "/./" path elements and convert "/A/./" path elements
  ** to just "/".
  */
  if( zFull ){
    int i, j;
    for(i=j=0; zFull[i]; i++){
      if( zFull[i]=='/' ){
        if( zFull[i+1]=='/' ) continue;
        if( zFull[i+1]=='.' && zFull[i+2]=='/' ){
          i += 1;
          continue;
        }
        if( zFull[i+1]=='.' && zFull[i+2]=='.' && zFull[i+3]=='/' ){
          while( j>0 && zFull[j-1]!='/' ){ j--; }
          i += 3;
          continue;
        }
      }
      zFull[j++] = zFull[i];
    }
    zFull[j] = 0;
  }
#endif

  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;
}

................................................................................
  unixFile *pNew;
  unixFile f;
  int rc;

  memset(&f, 0, sizeof(f));
  lockingStyle = sqlite3DetectLockingStyle(zFilename, h);
  if ( lockingStyle == posixLockingStyle ) {
    sqlite3OsEnterMutex();
    rc = findLockInfo(h, &f.pLock, &f.pOpen);
    sqlite3OsLeaveMutex();
    if( rc ){
      close(h);
      unlink(zFilename);
      return SQLITE_NOMEM;
    }
  } else {
    /*  pLock and pOpen are only used for posix advisory locking */
................................................................................
  }
  f.dirfd = -1;
  f.h = h;
  SET_THREADID(&f);
  pNew = sqlite3_malloc( sizeof(unixFile) );
  if( pNew==0 ){
    close(h);
    sqlite3OsEnterMutex();
    releaseLockInfo(f.pLock);
    releaseOpenCnt(f.pOpen);
    sqlite3OsLeaveMutex();
    *pId = 0;
    return SQLITE_NOMEM;
  }else{
    *pNew = f;
    switch(lockingStyle) {
      case afpLockingStyle: {
        /* afp locking uses the file path so it needs to be included in
................................................................................
    }
    *pId = (OsFile*)pNew;
    OpenCounter(+1);
    return SQLITE_OK;
  }
}
#else /* SQLITE_ENABLE_LOCKING_STYLE */
static int allocateUnixFile(
  int h,                 /* Open file descriptor on file being opened */
  sqlite3_file **pId,    /* Write the resul unixFile structure here */
  const char *zFilename, /* Name of the file being opened */
  int delFlag            /* If true, delete the file on or before closing */
){
  unixFile *pNew;
  unixFile f;
  int rc;

#ifdef FD_CLOEXEC
  fcntl(h, F_SETFD, fcntl(h, F_GETFD, 0) | FD_CLOEXEC);
#endif
  memset(&f, 0, sizeof(f));

  sqlite3OsEnterMutex();
  rc = findLockInfo(h, &f.pLock, &f.pOpen);
  sqlite3OsLeaveMutex();
  if( delFlag ){
    unlink(zFilename);
  }
  if( rc ){
    close(h);
    return SQLITE_NOMEM;
  }

  OSTRACE3("OPEN    %-3d %s\n", h, zFilename);
  f.dirfd = -1;
  f.h = h;
  SET_THREADID(&f);
  pNew = sqlite3_malloc( sizeof(unixFile) );
  if( pNew==0 ){
    close(h);
    sqlite3OsEnterMutex();
    releaseLockInfo(f.pLock);
    releaseOpenCnt(f.pOpen);
    sqlite3OsLeaveMutex();
    *pId = 0;
    return SQLITE_NOMEM;
  }else{
    *pNew = f;

    pNew->pMethod = &sqlite3UnixIoMethod;
    *pId = (sqlite3_file*)pNew;
    OpenCounter(+1);
    return SQLITE_OK;
  }
}
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

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



































































































































































































#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
#include <dlfcn.h>
void *sqlite3UnixDlopen(const char *zFilename){

  return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL);
}












void *sqlite3UnixDlsym(void *pHandle, const char *zSymbol){
  return dlsym(pHandle, zSymbol);
}
int sqlite3UnixDlclose(void *pHandle){
  return dlclose(pHandle);
}
#endif /* SQLITE_OMIT_LOAD_EXTENSION */












/*
** 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 sqlite3UnixRandomSeed(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.
  **
  ** When testing, initializing zBuf[] to zero is all we do.  That means
  ** that we always use the same random number sequence.  This makes the
  ** tests repeatable.
  */
  memset(zBuf, 0, 256);
#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(time_t)], &pid, sizeof(pid));

    }else{
      read(fd, zBuf, 256);
      close(fd);
    }
  }
#endif
  return SQLITE_OK;
}


/*
** Sleep for a little while.  Return the amount of time slept.
** The argument is the number of milliseconds we want to sleep.
*/
int sqlite3UnixSleep(int ms){

#if defined(HAVE_USLEEP) && HAVE_USLEEP
  usleep(ms*1000);
  return ms;
#else
  sleep((ms+999)/1000);
  return 1000*((ms+999)/1000);
#endif
}

/*
** Static variables used for thread synchronization.
**
** inMutex      the nesting depth of the recursive mutex.  The thread
**              holding mutexMain can read this variable at any time.
**              But is must hold mutexAux to change this variable.  Other
**              threads must hold mutexAux to read the variable and can
**              never write.
**
** mutexOwner   The thread id of the thread holding mutexMain.  Same
**              access rules as for inMutex.
**
** mutexOwnerValid   True if the value in mutexOwner is valid.  The same
**                   access rules apply as for inMutex.
**
** mutexMain    The main mutex.  Hold this mutex in order to get exclusive
**              access to SQLite data structures.
**
** mutexAux     An auxiliary mutex needed to access variables defined above.
**
** Mutexes are always acquired in this order: mutexMain mutexAux.   It
** is not necessary to acquire mutexMain in order to get mutexAux - just
** do not attempt to acquire them in the reverse order: mutexAux mutexMain.
** Either get the mutexes with mutexMain first or get mutexAux only.
**
** When running on a platform where the three variables inMutex, mutexOwner,
** and mutexOwnerValid can be set atomically, the mutexAux is not required.
** On many systems, all three are 32-bit integers and writing to a 32-bit
** integer is atomic.  I think.  But there are no guarantees.  So it seems
** safer to protect them using mutexAux.
*/
static int inMutex = 0;
#ifdef SQLITE_UNIX_THREADS
static pthread_t mutexOwner;          /* Thread holding mutexMain */
static int mutexOwnerValid = 0;       /* True if mutexOwner is valid */
static pthread_mutex_t mutexMain = PTHREAD_MUTEX_INITIALIZER; /* The mutex */
static pthread_mutex_t mutexAux = PTHREAD_MUTEX_INITIALIZER;  /* Aux mutex */
#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.
**
** As of version 3.3.2, this mutex must be recursive.
*/
void sqlite3UnixEnterMutex(){
#ifdef SQLITE_UNIX_THREADS
  pthread_mutex_lock(&mutexAux);
  if( !mutexOwnerValid || !pthread_equal(mutexOwner, pthread_self()) ){
    pthread_mutex_unlock(&mutexAux);
    pthread_mutex_lock(&mutexMain);
    assert( inMutex==0 );
    assert( !mutexOwnerValid );
    pthread_mutex_lock(&mutexAux);
    mutexOwner = pthread_self();
    mutexOwnerValid = 1;
  }
  inMutex++;
  pthread_mutex_unlock(&mutexAux);
#else
  inMutex++;
#endif
}
void sqlite3UnixLeaveMutex(){
  assert( inMutex>0 );
#ifdef SQLITE_UNIX_THREADS
  pthread_mutex_lock(&mutexAux);
  inMutex--;
  assert( pthread_equal(mutexOwner, pthread_self()) );
  if( inMutex==0 ){
    assert( mutexOwnerValid );
    mutexOwnerValid = 0;
    pthread_mutex_unlock(&mutexMain);
  }
  pthread_mutex_unlock(&mutexAux);
#else
  inMutex--;
#endif
}

/*
** Return TRUE if the mutex is currently held.
**
** If the thisThrd parameter is true, return true only if the
** calling thread holds the mutex.  If the parameter is false, return
** true if any thread holds the mutex.
*/
int sqlite3UnixInMutex(int thisThrd){
#ifdef SQLITE_UNIX_THREADS
  int rc;
  pthread_mutex_lock(&mutexAux);
  rc = inMutex>0 && (thisThrd==0 || pthread_equal(mutexOwner,pthread_self()));
  pthread_mutex_unlock(&mutexAux);
  return rc;
#else
  return inMutex>0;
#endif
}

/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3OsCurrentTime().  This is used for testing.
*/
................................................................................
#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 sqlite3UnixCurrentTime(double *prNow){
#ifdef NO_GETTOD
  time_t t;
  time(&t);
  *prNow = t/86400.0 + 2440587.5;
#else
  struct timeval sNow;
  gettimeofday(&sNow, 0);
................................................................................
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  return 0;
}
 


























#endif /* OS_UNIX */

/*
** Default permissions when creating a new file
*/
#ifndef SQLITE_DEFAULT_FILE_PERMISSIONS
# define SQLITE_DEFAULT_FILE_PERMISSIONS 0644
#endif

/*
** Maximum supported path-length.
*/
#define MAX_PATHNAME 512


/*
** The unixFile structure is subclass of OsFile specific for the unix
** protability layer.
*/
typedef struct unixFile unixFile;
................................................................................
        afpLockingStyle,             /* use afp locks */
        flockLockingStyle,           /* use flock() */
        dotlockLockingStyle,         /* use <file>.lock files */
        noLockingStyle,              /* useful for read-only file system */
        unsupportedLockingStyle      /* indicates unsupported file system */
} sqlite3LockingStyle;
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

static void enterMutex(){
  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL));
}
static void leaveMutex(){
  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL));
}

#ifdef SQLITE_UNIX_THREADS
/*
** This variable records whether or not threads can override each others
** locks.
**
**    0:  No.  Threads cannot override each others locks.
................................................................................
}
#endif /* SQLITE_UNIX_THREADS */

/*
** Release a lockInfo structure previously allocated by findLockInfo().
*/
static void releaseLockInfo(struct lockInfo *pLock){

  if (pLock == NULL)
    return;
  pLock->nRef--;
  if( pLock->nRef==0 ){
    sqlite3HashInsert(&lockHash, &pLock->key, sizeof(pLock->key), 0);
    sqlite3_free(pLock);
  }
}

/*
** Release a openCnt structure previously allocated by findLockInfo().
*/
static void releaseOpenCnt(struct openCnt *pOpen){

  if (pOpen == NULL)
    return;
  pOpen->nRef--;
  if( pOpen->nRef==0 ){
    sqlite3HashInsert(&openHash, &pOpen->key, sizeof(pOpen->key), 0);
    free(pOpen->aPending);
    sqlite3_free(pOpen);
................................................................................
  struct openKey key2;
  struct stat statbuf;
  struct lockInfo *pLock;
  struct openCnt *pOpen;
  rc = fstat(fd, &statbuf);
  if( rc!=0 ) return 1;


  memset(&key1, 0, sizeof(key1));
  key1.dev = statbuf.st_dev;
  key1.ino = statbuf.st_ino;
#ifdef SQLITE_UNIX_THREADS
  if( threadsOverrideEachOthersLocks<0 ){
    testThreadLockingBehavior(fd);
  }
................................................................................
** and *pReadonly is set to 0 if the file was opened for reading and
** writing or 1 if the file was opened read-only.  The function returns
** SQLITE_OK.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id and *pReadonly unchanged.
*/
#if 0
int sqlite3UnixOpenReadWrite(
  const char *zFilename,
  sqlite3_file **pId,
  int *pReadonly
){
  int h;
  
................................................................................
  if( h<0 ){
    return SQLITE_CANTOPEN;
  }
  return CRASH_TEST_OVERRIDE(
    zFilename, pId, allocateUnixFile(h, pId, zFilename, 0)
  );
}
#endif

/*
** 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.
**
................................................................................
#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
  struct stat buf;
................................................................................
** return zero.
*/
static int unixCheckReservedLock(sqlite3_file *id){
  int r = 0;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  enterMutex(); /* 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.
................................................................................
    lock.l_type = F_WRLCK;
    fcntl(pFile->h, F_GETLK, &lock);
    if( lock.l_type!=F_UNLCK ){
      r = 1;
    }
  }
  
  leaveMutex();
  OSTRACE3("TEST WR-LOCK %d %d\n", pFile->h, r);

  return r;
}

/*
** Lock the file with the lock specified by parameter locktype - one
................................................................................
  assert( pFile );
  OSTRACE7("LOCK    %d %s was %s(%s,%d) pid=%d\n", pFile->h,
      locktypeName(locktype), locktypeName(pFile->locktype),
      locktypeName(pLock->locktype), pLock->cnt , getpid());

  /* 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
  ** enterMutex() hasn't been called yet.
  */
  if( pFile->locktype>=locktype ){
    OSTRACE3("LOCK    %d %s ok (already held)\n", pFile->h,
            locktypeName(locktype));
    return SQLITE_OK;
  }

................................................................................
  */
  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
  */
  enterMutex();

  /* Make sure the current thread owns the pFile.
  */
  rc = transferOwnership(pFile);
  if( rc!=SQLITE_OK ){
    leaveMutex();
    return rc;
  }
  pLock = pFile->pLock;

  /* If some thread using this PID has a lock via a different OsFile*
  ** handle that precludes the requested lock, return BUSY.
  */
................................................................................
    pLock->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;
    pLock->locktype = PENDING_LOCK;
  }

end_lock:
  leaveMutex();
  OSTRACE4("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
................................................................................
  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  if( CHECK_THREADID(pFile) ){
    return SQLITE_MISUSE;
  }
  enterMutex();
  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;
................................................................................
        close(pOpen->aPending[i]);
      }
      free(pOpen->aPending);
      pOpen->nPending = 0;
      pOpen->aPending = 0;
    }
  }
  leaveMutex();
  pFile->locktype = locktype;
  return rc;
}

/*
** Close a file.
*/
static int unixClose(sqlite3_file *id){
  unixFile *pFile = (unixFile *)id;
  if( !pFile ) return SQLITE_OK;
  unixUnlock(id, NO_LOCK);
  if( pFile->dirfd>=0 ) close(pFile->dirfd);
  pFile->dirfd = -1;
  enterMutex();

  if( pFile->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.
    */
................................................................................
  }else{
    /* There are no outstanding locks so we can close the file immediately */
    close(pFile->h);
  }
  releaseLockInfo(pFile->pLock);
  releaseOpenCnt(pFile->pOpen);

  leaveMutex();
  pFile->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", pFile->h);
  OpenCounter(-1);
  memset(pFile, 0, sizeof(unixFile));
  return SQLITE_OK;
}


#ifdef SQLITE_ENABLE_LOCKING_STYLE
#pragma mark AFP Support

................................................................................
  int gotPendingLock = 0;
  
  assert( pFile );
  OSTRACE5("LOCK    %d %s was %s pid=%d\n", pFile->h,
         locktypeName(locktype), locktypeName(pFile->locktype), getpid());  
  /* If there is already a lock of this type or more restrictive on the
    ** OsFile, do nothing. Don't use the afp_end_lock: exit path, as
    ** enterMutex() hasn't been called yet.
    */
  if( pFile->locktype>=locktype ){
    OSTRACE3("LOCK    %d %s ok (already held)\n", pFile->h,
           locktypeName(locktype));
    return SQLITE_OK;
  }

................................................................................
    */
  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
    */
  enterMutex();

  /* Make sure the current thread owns the pFile.
    */
  rc = transferOwnership(pFile);
  if( rc!=SQLITE_OK ){
    leaveMutex();
    return rc;
  }
    
  /* 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( rc==SQLITE_OK ){
    pFile->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;
  }
  
afp_end_lock:
    leaveMutex();
  OSTRACE4("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
................................................................................
  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  if( CHECK_THREADID(pFile) ){
    return SQLITE_MISUSE;
  }
  enterMutex();
  if( pFile->locktype>SHARED_LOCK ){
    if( locktype==SHARED_LOCK ){
      int failed = 0;

      /* unlock the exclusive range - then re-establish the shared lock */
      if (pFile->locktype==EXCLUSIVE_LOCK) {
        failed = _AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST, 
................................................................................
                               SHARED_FIRST + context->sharedLockByte, 1, 0);
    if (failed) {
      rc = SQLITE_IOERR_UNLOCK;  /* This should never happen */
    }
  }
  if (rc == SQLITE_OK)
    pFile->locktype = locktype;
  leaveMutex();
  return rc;
}

/*
 ** Close a file & cleanup AFP specific locking context 
 */
static int afpUnixClose(OsFile **pId) {
................................................................................
  unixFile *id = (unixFile*)*pId;
  
  if( !id ) return SQLITE_OK;
  flockUnixUnlock(*pId, NO_LOCK);
  
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  enterMutex();
  
  close(id->h);  
  leaveMutex();
  id->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  sqlite3_free(id);
  *pId = 0;
  return SQLITE_OK;
}
................................................................................
      sqlite3_free( ( (dotlockLockingContext *)
        id->lockingContext)->lockPath);
    sqlite3_free(id->lockingContext);
  }
  
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  enterMutex();
  
  close(id->h);
  
  leaveMutex();
  id->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  sqlite3_free(id);
  *pId = 0;
  return SQLITE_OK;
}
................................................................................
 */
static int nolockUnixClose(OsFile **pId) {
  unixFile *id = (unixFile*)*pId;
  
  if( !id ) return SQLITE_OK;
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  enterMutex();
  
  close(id->h);
  
  leaveMutex();
  id->isOpen = 0;
  OSTRACE2("CLOSE   %-3d\n", id->h);
  OpenCounter(-1);
  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;
}

................................................................................
  unixFile *pNew;
  unixFile f;
  int rc;

  memset(&f, 0, sizeof(f));
  lockingStyle = sqlite3DetectLockingStyle(zFilename, h);
  if ( lockingStyle == posixLockingStyle ) {
    enterMutex();
    rc = findLockInfo(h, &f.pLock, &f.pOpen);
    leaveMutex();
    if( rc ){
      close(h);
      unlink(zFilename);
      return SQLITE_NOMEM;
    }
  } else {
    /*  pLock and pOpen are only used for posix advisory locking */
................................................................................
  }
  f.dirfd = -1;
  f.h = h;
  SET_THREADID(&f);
  pNew = sqlite3_malloc( sizeof(unixFile) );
  if( pNew==0 ){
    close(h);
    enterMutex();
    releaseLockInfo(f.pLock);
    releaseOpenCnt(f.pOpen);
    leaveMutex();
    *pId = 0;
    return SQLITE_NOMEM;
  }else{
    *pNew = f;
    switch(lockingStyle) {
      case afpLockingStyle: {
        /* afp locking uses the file path so it needs to be included in
................................................................................
    }
    *pId = (OsFile*)pNew;
    OpenCounter(+1);
    return SQLITE_OK;
  }
}
#else /* SQLITE_ENABLE_LOCKING_STYLE */
static int fillInUnixFile(
  int h,                 /* Open file descriptor on file being opened */
  sqlite3_file *pId,     /* Write to the unixFile structure here */
  const char *zFilename  /* Name of the file being opened */

){
  unixFile *pNew = (unixFile *)pId;

  int rc;

#ifdef FD_CLOEXEC
  fcntl(h, F_SETFD, fcntl(h, F_GETFD, 0) | FD_CLOEXEC);
#endif


  enterMutex();
  rc = findLockInfo(h, &pNew->pLock, &pNew->pOpen);
  leaveMutex();



  if( rc ){
    close(h);
    return SQLITE_NOMEM;
  }

  OSTRACE3("OPEN    %-3d %s\n", h, zFilename);
  pNew->dirfd = -1;
  pNew->h = h;
  SET_THREADID(pNew);












  pNew->pMethod = &sqlite3UnixIoMethod;

  OpenCounter(+1);
  return SQLITE_OK;
}

#endif /* SQLITE_ENABLE_LOCKING_STYLE */

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

/*
** Previously, the SQLite OS layer used three functions in place of this
** one:
**
**     sqlite3OsOpenReadWrite();
**     sqlite3OsOpenReadOnly();
**     sqlite3OsOpenExclusive();
**
** These calls correspond to the following combinations of flags:
**
**     ReadWrite() ->     (READWRITE | CREATE)
**     ReadOnly()  ->     (READONLY) 
**     OpenExclusive() -> (READWRITE | CREATE | EXCLUSIVE)
**
** The old OpenExclusive() accepted a boolean argument - "delFlag". If
** true, the file was configured to be automatically deleted when the
** file handle closed. To achieve the same effect using this new 
** interface, add the DELETEONCLOSE flag to those specified above for 
** OpenExclusive().
*/
static int unixOpen(
  void *pNotUsed, 
  const char *zPath, 
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  int fd = 0;
  int oflags = 0;

  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
  int isCreate     = (flags & SQLITE_OPEN_CREATE);
  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);

  /* Exactly one of the READWRITE and READONLY flags must be set */
  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));

  /* If isCreate is true, then the file must be opened for read/write access. */
  assert(isCreate==0 || isReadWrite);

  /* If isExclusive is true, then isCreate must also be true */
  assert(isExclusive==0 || isCreate);

  if( isReadonly )  oflags |= O_RDONLY;
  if( isReadWrite ) oflags |= O_RDWR;
  if( isCreate )    oflags |= O_CREAT;
  if( isExclusive ) oflags |= (O_EXCL|O_NOFOLLOW);
  oflags |= (O_LARGEFILE|O_BINARY);

  memset(pFile, 0, sizeof(unixFile));
  fd = open(zPath, oflags, isDelete?0600:SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( fd<0 && isReadWrite && !isExclusive ){
    /* Failed to open the file for read/write access. Try read-only. */
    flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
    flags |= SQLITE_OPEN_READONLY;
    return unixOpen(pNotUsed, zPath, pFile, flags, pOutFlags);
  }
  if( fd<0 ){
    return SQLITE_CANTOPEN;
  }
  if( isDelete ){
    unlink(zPath);
  }
  if( pOutFlags ){
    *pOutFlags = flags;
  }

  assert(fd!=0);
  return fillInUnixFile(fd, pFile, zPath);
}

/*
** Delete the file at zPath.
*/
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:
      amode = W_OK|R_OK;
      break;
    case SQLITE_ACCESS_READONLY:
      amode = R_OK;
      break;

    default:
      assert(!"Invalid flags argument");
  }
  return (access(zPath, amode)==0);
}

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at least MAX_PATHNAME characters.
*/
static int unixGetTempName(void *pNotUsed, char *zBuf){
  static const char *azDirs[] = {
     0,
     "/var/tmp",
     "/usr/tmp",
     "/tmp",
     ".",
  };
  static const unsigned char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  struct stat buf;
  const char *zDir = ".";
  azDirs[0] = sqlite3_temp_directory;
  for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
    if( azDirs[i]==0 ) continue;
    if( stat(azDirs[i], &buf) ) continue;
    if( !S_ISDIR(buf.st_mode) ) continue;
    if( access(azDirs[i], 07) ) continue;
    zDir = azDirs[i];
    break;
  }
  do{
    sqlite3_snprintf(MAX_PATHNAME-17, zBuf, "%s/"TEMP_FILE_PREFIX, zDir);
    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;
  }while( access(zBuf,0)==0 );
  return SQLITE_OK;
}


/*
** Turn a relative pathname into a full pathname. The relative path
** is stored as a nul-terminated string in the buffer pointed to by
** zPath. 
**
** zOut points to a buffer of at least sqlite3_vfs.mxPathname bytes 
** (in this case, MAX_PATHNAME bytes). The full-path is written to
** this buffer before returning.
*/
static int unixFullPathname(void *pNotUsed, const char *zPath, char *zOut){
  zOut[MAX_PATHNAME-1] = '\0';
  if( zPath[0]=='/' ){
    strncpy(zOut, zPath, MAX_PATHNAME-1);
  }else{
    int nCwd;
    if( getcwd(zOut, MAX_PATHNAME-1)==0 ){
      return SQLITE_ERROR;
    }
    nCwd = strlen(zOut);
    zOut[nCwd] = '/';
    strncpy(&zOut[nCwd+1], zPath, MAX_PATHNAME-1-nCwd-1);
  }
  return SQLITE_OK;

#if 0
  /*
  ** Remove "/./" path elements and convert "/A/./" path elements
  ** to just "/".
  */
  if( zFull ){
    int i, j;
    for(i=j=0; zFull[i]; i++){
      if( zFull[i]=='/' ){
        if( zFull[i+1]=='/' ) continue;
        if( zFull[i+1]=='.' && zFull[i+2]=='/' ){
          i += 1;
          continue;
        }
        if( zFull[i+1]=='.' && zFull[i+2]=='.' && zFull[i+3]=='/' ){
          while( j>0 && zFull[j-1]!='/' ){ j--; }
          i += 3;
          continue;
        }
      }
      zFull[j++] = zFull[i];
    }
    zFull[j] = 0;
  }
#endif
}


#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
#include <dlfcn.h>

static void *unixDlOpen(void *pNotUsed, const char *zFilename){
  return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL);
}
static void unixDlError(void *pNotUsed, int nBuf, char *zBufOut){
  char *zErr;
  enterMutex();
  zErr = dlerror();
  if( zErr ){
    strncpy(zBufOut, zErr, nBuf-1);
    zBufOut[nBuf-1] = '\0';
  }else if(nBuf>0) {
    zBufOut[0] = '\0';
  }
  leaveMutex();
}
void *unixDlSym(void *pHandle, const char *zSymbol){
  return dlsym(pHandle, zSymbol);
}
void unixDlClose(void *pHandle){
  dlclose(pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #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.
  **
  ** When testing, initializing zBuf[] to zero is all we do.  That means
  ** that we always use the same random number sequence.  This makes the
  ** tests repeatable.
  */
  memset(zBuf, 0, nBuf);
#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;
}


/*
** Sleep for a little while.  Return the amount of time slept.
** The argument is the number of microseconds we want to sleep.
*/

static int unixSleep(void *pNotUsed, int microseconds){
#if defined(HAVE_USLEEP) && HAVE_USLEEP
  usleep(microseconds);
  return microseconds;
#else

  int seconds = (microseconds+999999)/1000000;
  sleep(seconds);



































































































  return seconds;


#endif
}

/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3OsCurrentTime().  This is used for testing.
*/
................................................................................
#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(void *pNotUsed, double *prNow){
#ifdef NO_GETTOD
  time_t t;
  time(&t);
  *prNow = t/86400.0 + 2440587.5;
#else
  struct timeval sNow;
  gettimeofday(&sNow, 0);
................................................................................
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  return 0;
}


sqlite3_vfs sqlite3DefaultVfs = {
  1,                  /* iVersion */
  sizeof(unixFile),   /* szOsFile */
  MAX_PATHNAME,       /* mxPathname */
  0,                  /* nRef */
  0,                  /* vfsMutex */
  0,                  /* pNext */
  0,                  /* pPrev */
  "unix",             /* zName */
  0,                  /* pAppData */

  unixOpen,           /* xOpen */
  unixDelete,         /* xDelete */
  unixAccess,         /* xAccess */
  unixGetTempName,    /* xGetTempName */
  unixFullPathname,   /* xFullPathname */
  unixDlOpen,         /* xDlOpen */
  unixDlError,        /* xDlError */
  unixDlSym,          /* xDlSym */
  unixDlClose,        /* xDlClose */
  unixRandomness,     /* xRandomness */
  unixSleep,          /* xSleep */
  unixCurrentTime     /* xCurrentTime */
};
 
#endif /* OS_UNIX */

** 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 1.358 2007/08/16 10:09:03 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
** and is returned as the result of every major pager API call.  The
** SQLITE_FULL return code is slightly different. It persists only until the
** next successful rollback is performed on the pager cache. Also,
** SQLITE_FULL does not affect the sqlite3PagerGet() and sqlite3PagerLookup()
** APIs, they may still be used successfully.
*/
struct Pager {

  u8 journalOpen;             /* True if journal file descriptors is valid */
  u8 journalStarted;          /* True if header of journal is synced */
  u8 useJournal;              /* Use a rollback journal on this file */
  u8 noReadlock;              /* Do not bother to obtain readlocks */
  u8 stmtOpen;                /* True if the statement subjournal is open */
  u8 stmtInUse;               /* True we are in a statement subtransaction */
  u8 stmtAutoopen;            /* Open stmt journal when main journal is opened*/
................................................................................
  int rc2 = SQLITE_OK;
  assert( !MEMDB );
  if( pPager->state<PAGER_RESERVED ){
    return SQLITE_OK;
  }
  sqlite3PagerStmtCommit(pPager);
  if( pPager->stmtOpen && !pPager->exclusiveMode ){
    sqlite3OsClose(&pPager->stfd);
    pPager->stmtOpen = 0;
  }
  if( pPager->journalOpen ){
    if( pPager->exclusiveMode 
          && (rc = sqlite3OsTruncate(pPager->jfd, 0))==SQLITE_OK ){;
      pPager->journalOff = 0;
      pPager->journalStarted = 0;
    }else{
      sqlite3OsClose(&pPager->jfd);
      pPager->journalOpen = 0;
      if( rc==SQLITE_OK ){
        rc = sqlite3OsDelete(pPager->zJournal);
      }
    }
    sqlite3_free( pPager->aInJournal );
    pPager->aInJournal = 0;
    for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
      pPg->inJournal = 0;
      pPg->dirty = 0;
................................................................................
** and does so if it is.
**
** The master journal file contains the names of all child journals.
** To tell if a master journal can be deleted, check to each of the
** children.  If all children are either missing or do not refer to
** a different master journal, then this master journal can be deleted.
*/
static int pager_delmaster(const char *zMaster){

  int rc;
  int master_open = 0;
  sqlite3_file *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 = sqlite3OsOpenReadOnly(zMaster, &master);
  assert( rc!=SQLITE_OK || 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
................................................................................
    ** sqlite3_malloc() and pointed to by zMasterJournal. 
    */
    zMasterJournal = (char *)sqlite3_malloc(nMasterJournal);
    if( !zMasterJournal ){
      rc = SQLITE_NOMEM;
      goto delmaster_out;
    }
    rc = sqlite3OsRead(master, zMasterJournal, nMasterJournal, 0);
    if( rc!=SQLITE_OK ) goto delmaster_out;

    zJournal = zMasterJournal;
    while( (zJournal-zMasterJournal)<nMasterJournal ){
      if( sqlite3OsFileExists(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.
        */
        sqlite3_file *journal = 0;
        int c;

        rc = sqlite3OsOpenReadOnly(zJournal, &journal);
        assert( rc!=SQLITE_OK || 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;
        sqlite3_free(zMasterPtr);
        if( c ){
................................................................................
          goto delmaster_out;
        }
      }
      zJournal += (strlen(zJournal)+1);
    }
  }
  
  rc = sqlite3OsDelete(zMaster);

delmaster_out:
  if( zMasterJournal ){
    sqlite3_free(zMasterJournal);
  }  
  if( master_open ){
    sqlite3OsClose(&master);
  }

  return rc;
}


static void pager_truncate_cache(Pager *pPager);

/*
................................................................................
** is then deleted and SQLITE_OK returned, just as if no corruption had
** been encountered.
**
** If an I/O or malloc() error occurs, the journal-file is not deleted
** and an error code is returned.
*/
static int pager_playback(Pager *pPager, int isHot){

  i64 szJ;                 /* Size of the journal file in bytes */
  u32 nRec;                /* Number of Records in the journal */
  int i;                   /* Loop counter */
  Pgno mxPg = 0;           /* Size of the original file in pages */
  int rc;                  /* Result code of a subroutine */
  char *zMaster = 0;       /* Name of master journal file if any */

................................................................................
  /* 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 && !sqlite3OsFileExists(zMaster)) ){


    sqlite3_free(zMaster);
    zMaster = 0;
    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
    goto end_playback;
  }
  pPager->journalOff = 0;

................................................................................
    rc = pager_end_transaction(pPager);
  }
  if( zMaster ){
    /* If there was a master journal and this routine will return success,
    ** see if it is possible to delete the master journal.
    */
    if( rc==SQLITE_OK ){
      rc = pager_delmaster(zMaster);
    }
    sqlite3_free(zMaster);
  }

  /* The Pager.sectorSize variable may have been updated while rolling
  ** back a journal created by a process with a different sector size
  ** value. Reset it to the correct value for this process.
................................................................................
**
** Write the file descriptor into *fd.  Return SQLITE_OK on success or some
** other error code if we fail.
**
** The OS will automatically delete the temporary file when it is
** closed.
*/
static int sqlite3PagerOpentemp(sqlite3_file **pFd){




  int cnt = 8;
  int rc;
  char zFile[SQLITE_TEMPNAME_SIZE];











#ifdef SQLITE_TEST
  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
#endif

  do{
    cnt--;
    sqlite3OsTempFileName(zFile);

    rc = sqlite3OsOpenExclusive(zFile, pFd, 1);
    assert( rc!=SQLITE_OK || *pFd );
  }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
** the first call to sqlite3PagerGet() and is only held open until the
................................................................................
** automatically when it is closed.
**
** If zFilename is ":memory:" then all information is held in cache.
** It is never written to disk.  This can be used to implement an
** in-memory database.
*/
int sqlite3PagerOpen(

  Pager **ppPager,         /* Return the Pager structure here */
  const char *zFilename,   /* Name of the database file to open */
  int nExtra,              /* Extra bytes append to each in-memory page */
  int flags                /* flags controlling this file */
){

  Pager *pPager = 0;
  char *zFullPathname = 0;
  int nameLen;  /* Compiler is wrong. This is always initialized before use */
  sqlite3_file *fd = 0;
  int rc = SQLITE_OK;
  int i;
  int tempFile = 0;
  int memDb = 0;
  int readOnly = 0;
  int useJournal = (flags & PAGER_OMIT_JOURNAL)==0;
  int noReadlock = (flags & PAGER_NO_READLOCK)!=0;
  char zTemp[SQLITE_TEMPNAME_SIZE];
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  /* A malloc() cannot fail in sqlite3ThreadData() as one or more calls to 
  ** malloc() must have already been made by this thread before it gets
  ** to this point. This means the ThreadData must have been allocated already
  ** so that ThreadData.nAlloc can be set. It would be nice to assert
  ** that ThreadData.nAlloc is non-zero, but alas this breaks test cases 
  ** written to invoke the pager directly.
................................................................................
  /* We used to test if malloc() had already failed before proceeding. 
  ** But the way this function is used in SQLite means that can never
  ** happen. Furthermore, if the malloc-failed flag is already set, 
  ** either the call to sqlite3StrDup() or sqlite3_malloc() below will
  ** fail shortly and SQLITE_NOMEM returned anyway.
  */
  *ppPager = 0;



















  /* Open the pager file and set zFullPathname to point at malloc()ed 
  ** memory containing the complete filename (i.e. including the directory).
  */
  if( zFilename && zFilename[0] ){
#ifndef SQLITE_OMIT_MEMORYDB
    if( strcmp(zFilename,":memory:")==0 ){
      memDb = 1;
      zFullPathname = sqlite3StrDup("");
    }else
#endif
    {
      zFullPathname = sqlite3OsFullPathname(zFilename);
      if( zFullPathname ){
        rc = sqlite3OsOpenReadWrite(zFullPathname, &fd, &readOnly);
        assert( rc!=SQLITE_OK || fd );






      }
    }
  }else{
    rc = sqlite3PagerOpentemp(&fd);
    sqlite3OsTempFileName(zTemp);
    zFilename = zTemp;
    zFullPathname = sqlite3OsFullPathname(zFilename);
    if( rc==SQLITE_OK ){
      tempFile = 1;
    }
  }

  /* Allocate the Pager structure. As part of the same allocation, allocate
  ** space for the full paths of the file, directory and journal 
  ** (Pager.zFilename, Pager.zDirectory and Pager.zJournal).
  */
  if( zFullPathname ){
    nameLen = strlen(zFullPathname);
    pPager = sqlite3MallocZero( sizeof(*pPager) + nameLen*3 + 30 );
    if( pPager && rc==SQLITE_OK ){
      pPager->pTmpSpace = (char *)sqlite3_malloc(SQLITE_DEFAULT_PAGE_SIZE);
    }
  }


  /* If an error occured in either of the blocks above, free the memory 
  ** pointed to by zFullPathname, free the Pager structure and close the 
  ** file. Since the pager is not allocated there is no need to set 
  ** any Pager.errMask variables.
  */
  if( !pPager || !zFullPathname || !pPager->pTmpSpace || rc!=SQLITE_OK ){
    sqlite3OsClose(&fd);
    sqlite3_free(zFullPathname);
    sqlite3_free(pPager);
    return ((rc==SQLITE_OK)?SQLITE_NOMEM:rc);
  }

  PAGERTRACE3("OPEN %d %s\n", FILEHANDLEID(fd), zFullPathname);
  IOTRACE(("OPEN %p %s\n", pPager, zFullPathname))
  pPager->zFilename = (char*)&pPager[1];
  pPager->zDirectory = &pPager->zFilename[nameLen+1];
  pPager->zJournal = &pPager->zDirectory[nameLen+1];
  memcpy(pPager->zFilename, zFullPathname, nameLen+1);
  memcpy(pPager->zDirectory, zFullPathname, nameLen+1);

  for(i=nameLen; i>0 && pPager->zDirectory[i-1]!='/'; i--){}
  if( i>0 ) pPager->zDirectory[i-1] = 0;
  memcpy(pPager->zJournal, zFullPathname,nameLen);
  sqlite3_free(zFullPathname);
  memcpy(&pPager->zJournal[nameLen], "-journal",sizeof("-journal"));
  pPager->fd = fd;
  /* pPager->journalOpen = 0; */
  pPager->useJournal = useJournal && !memDb;
  pPager->noReadlock = noReadlock && readOnly;
  /* pPager->stmtOpen = 0; */
  /* pPager->stmtInUse = 0; */
  /* pPager->nRef = 0; */
  pPager->dbSize = memDb-1;
................................................................................
  /* pPager->needSync = 0; */
  pPager->noSync = pPager->tempFile || !useJournal;
  pPager->fullSync = (pPager->noSync?0:1);
  /* pPager->pFirst = 0; */
  /* pPager->pFirstSynced = 0; */
  /* pPager->pLast = 0; */
  pPager->nExtra = FORCE_ALIGNMENT(nExtra);
  assert(fd||memDb);
  if( !memDb ){
    setSectorSize(pPager);
  }
  /* pPager->pBusyHandler = 0; */
  /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
  *ppPager = pPager;
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
................................................................................
  pager_reset(pPager);
  pagerUnlockAndRollback(pPager);
  enable_simulated_io_errors();
  PAGERTRACE2("CLOSE %d\n", PAGERID(pPager));
  IOTRACE(("CLOSE %p\n", pPager))
  assert( pPager->errCode || (pPager->journalOpen==0 && pPager->stmtOpen==0) );
  if( pPager->journalOpen ){
    sqlite3OsClose(&pPager->jfd);
  }
  sqlite3_free(pPager->aInJournal);
  if( pPager->stmtOpen ){
    sqlite3OsClose(&pPager->stfd);
  }
  sqlite3OsClose(&pPager->fd);
  /* Temp files are automatically deleted by the OS
  ** if( pPager->tempFile ){
  **   sqlite3OsDelete(pPager->zFilename);
  ** }
  */

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
................................................................................
** A hot journal is one that needs to be played back.
**
** 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( !sqlite3OsFileExists(pPager->zJournal) ){

    return 0;
  }
  if( sqlite3OsCheckReservedLock(pPager->fd) ){
    return 0;
  }
  if( sqlite3PagerPagecount(pPager)==0 ){
    sqlite3OsDelete(pPager->zJournal);
    return 0;
  }else{
    return 1;
  }
}

/*
................................................................................
  int i;

  /* If the the global mutex is held, this subroutine becomes a
  ** o-op; zero bytes of memory are freed.  This is because
  ** some of the code invoked by this function may also
  ** try to obtain the mutex, resulting in a deadlock.
  */

  if( sqlite3OsInMutex(0) ){
    return 0;
  }


  /* Outermost loop runs for at most two iterations. First iteration we
  ** try to find memory that can be released without calling fsync(). Second
  ** iteration (which only runs if the first failed to free nReq bytes of
  ** memory) is permitted to call fsync(). This is of course much more 
  ** expensive.
  */
................................................................................
** checks for a hot-journal file. If one is found, an emergency rollback
** is performed immediately.
*/
static int pagerSharedLock(Pager *pPager){
  int rc = SQLITE_OK;

  if( pPager->state==PAGER_UNLOCK ){

    if( !MEMDB ){
      assert( pPager->nRef==0 );
      if( !pPager->noReadlock ){
        rc = pager_wait_on_lock(pPager, SHARED_LOCK);
        if( rc!=SQLITE_OK ){
          return pager_error(pPager, rc);
        }
................................................................................
        ** Open the journal for read/write access. This is because in 
        ** exclusive-access mode the file descriptor will be kept open and
        ** possibly used for a transaction later on. On some systems, the
        ** OsTruncate() call used in exclusive-access mode also requires
        ** a read/write file handle.
        */
        rc = SQLITE_BUSY;
        if( sqlite3OsFileExists(pPager->zJournal) ){
          int ro;

          assert( !pPager->tempFile );
          rc = sqlite3OsOpenReadWrite(pPager->zJournal, &pPager->jfd, &ro);

          assert( rc!=SQLITE_OK || pPager->jfd );
          if( ro ){

            rc = SQLITE_BUSY;
            sqlite3OsClose(&pPager->jfd);
          }
        }
        if( rc!=SQLITE_OK ){
          pager_unlock(pPager);
          return SQLITE_BUSY;
        }
        pPager->journalOpen = 1;
................................................................................
** Create a journal file for pPager.  There should already be a RESERVED
** or EXCLUSIVE lock on the database file when this routine is called.
**
** Return SQLITE_OK if everything.  Return an error code and release the
** write lock if anything goes wrong.
*/
static int pager_open_journal(Pager *pPager){



  int rc;
  assert( !MEMDB );
  assert( pPager->state>=PAGER_RESERVED );
  assert( pPager->journalOpen==0 );
  assert( pPager->useJournal );
  assert( pPager->aInJournal==0 );
  sqlite3PagerPagecount(pPager);
  pPager->aInJournal = sqlite3MallocZero( pPager->dbSize/8 + 1 );
  if( pPager->aInJournal==0 ){
    rc = SQLITE_NOMEM;
    goto failed_to_open_journal;
  }
  rc = sqlite3OsOpenExclusive(pPager->zJournal, &pPager->jfd,

                                 pPager->tempFile);



  assert( rc!=SQLITE_OK || pPager->jfd );
  pPager->journalOff = 0;
  pPager->setMaster = 0;
  pPager->journalHdr = 0;
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_NOMEM ){
      sqlite3OsDelete(pPager->zJournal);
    }
    goto failed_to_open_journal;
  }
#if 0
  sqlite3OsSetFullSync(pPager->jfd, pPager->full_fsync);
  sqlite3OsSetFullSync(pPager->fd, pPager->full_fsync);
  sqlite3OsOpenDirectory(pPager->jfd, pPager->zDirectory);
................................................................................
  assert( pPager->stmtJSize == pPager->journalOff );
#endif
  pPager->stmtJSize = pPager->journalOff;
  pPager->stmtSize = pPager->dbSize;
  pPager->stmtHdrOff = 0;
  pPager->stmtCksum = pPager->cksumInit;
  if( !pPager->stmtOpen ){
    rc = sqlite3PagerOpentemp(&pPager->stfd);
    if( rc ) goto stmt_begin_failed;
    pPager->stmtOpen = 1;
    pPager->stmtNRec = 0;
  }
  pPager->stmtInUse = 1;
  return SQLITE_OK;
 

** 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 1.359 2007/08/17 15:53:37 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
** and is returned as the result of every major pager API call.  The
** SQLITE_FULL return code is slightly different. It persists only until the
** next successful rollback is performed on the pager cache. Also,
** SQLITE_FULL does not affect the sqlite3PagerGet() and sqlite3PagerLookup()
** APIs, they may still be used successfully.
*/
struct Pager {
  sqlite3_vfs *pVfs;          /* OS functions to use for IO */
  u8 journalOpen;             /* True if journal file descriptors is valid */
  u8 journalStarted;          /* True if header of journal is synced */
  u8 useJournal;              /* Use a rollback journal on this file */
  u8 noReadlock;              /* Do not bother to obtain readlocks */
  u8 stmtOpen;                /* True if the statement subjournal is open */
  u8 stmtInUse;               /* True we are in a statement subtransaction */
  u8 stmtAutoopen;            /* Open stmt journal when main journal is opened*/
................................................................................
  int rc2 = SQLITE_OK;
  assert( !MEMDB );
  if( pPager->state<PAGER_RESERVED ){
    return SQLITE_OK;
  }
  sqlite3PagerStmtCommit(pPager);
  if( pPager->stmtOpen && !pPager->exclusiveMode ){
    sqlite3OsClose(pPager->stfd);
    pPager->stmtOpen = 0;
  }
  if( pPager->journalOpen ){
    if( pPager->exclusiveMode 
          && (rc = sqlite3OsTruncate(pPager->jfd, 0))==SQLITE_OK ){;
      pPager->journalOff = 0;
      pPager->journalStarted = 0;
    }else{
      sqlite3OsClose(pPager->jfd);
      pPager->journalOpen = 0;
      if( rc==SQLITE_OK ){
        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal);
      }
    }
    sqlite3_free( pPager->aInJournal );
    pPager->aInJournal = 0;
    for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
      pPg->inJournal = 0;
      pPg->dirty = 0;
................................................................................
** and does so if it is.
**
** The master journal file contains the names of all child journals.
** To tell if a master journal can be deleted, check to each of the
** children.  If all children are either missing or do not refer to
** a different master journal, then this master journal can be deleted.
*/
static int pager_delmaster(Pager *pPager, const char *zMaster){
  sqlite3_vfs *pVfs = pPager->pVfs;
  int rc;
  int master_open = 0;
  sqlite3_file *pMaster;
  sqlite3_file *pJournal;
  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.
  */
  pMaster = (sqlite3_file *)sqlite3_malloc(pVfs->szOsFile * 2);
  if( !pMaster ){
    rc = SQLITE_NOMEM;
  }else{
    pJournal = (sqlite3_file *)(((u8 *)pMaster) + pVfs->szOsFile);
    rc = sqlite3OsOpen(pVfs, zMaster, pMaster, SQLITE_OPEN_READONLY, 0);
  }
  if( rc!=SQLITE_OK ) goto delmaster_out;
  master_open = 1;

  rc = sqlite3OsFileSize(pMaster, &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
................................................................................
    ** sqlite3_malloc() and pointed to by zMasterJournal. 
    */
    zMasterJournal = (char *)sqlite3_malloc(nMasterJournal);
    if( !zMasterJournal ){
      rc = SQLITE_NOMEM;
      goto delmaster_out;
    }
    rc = sqlite3OsRead(pMaster, zMasterJournal, nMasterJournal, 0);
    if( rc!=SQLITE_OK ) goto delmaster_out;

    zJournal = zMasterJournal;
    while( (zJournal-zMasterJournal)<nMasterJournal ){
      if( sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS) ){
        /* 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.
        */

        int c;



        rc = sqlite3OsOpen(pVfs, zJournal, pJournal, SQLITE_OPEN_READONLY, 0);
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }

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

        c = zMasterPtr!=0 && strcmp(zMasterPtr, zMaster)==0;
        sqlite3_free(zMasterPtr);
        if( c ){
................................................................................
          goto delmaster_out;
        }
      }
      zJournal += (strlen(zJournal)+1);
    }
  }
  
  rc = sqlite3OsDelete(pVfs, zMaster);

delmaster_out:
  if( zMasterJournal ){
    sqlite3_free(zMasterJournal);
  }  
  if( master_open ){
    sqlite3OsClose(pMaster);
  }
  sqlite3_free(pMaster);
  return rc;
}


static void pager_truncate_cache(Pager *pPager);

/*
................................................................................
** is then deleted and SQLITE_OK returned, just as if no corruption had
** been encountered.
**
** If an I/O or malloc() error occurs, the journal-file is not deleted
** and an error code is returned.
*/
static int pager_playback(Pager *pPager, int isHot){
  sqlite3_vfs *pVfs = pPager->pVfs;
  i64 szJ;                 /* Size of the journal file in bytes */
  u32 nRec;                /* Number of Records in the journal */
  int i;                   /* Loop counter */
  Pgno mxPg = 0;           /* Size of the original file in pages */
  int rc;                  /* Result code of a subroutine */
  char *zMaster = 0;       /* Name of master journal file if any */

................................................................................
  /* 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 && !sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS)) 
  ){
    sqlite3_free(zMaster);
    zMaster = 0;
    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
    goto end_playback;
  }
  pPager->journalOff = 0;

................................................................................
    rc = pager_end_transaction(pPager);
  }
  if( zMaster ){
    /* If there was a master journal and this routine will return success,
    ** see if it is possible to delete the master journal.
    */
    if( rc==SQLITE_OK ){
      rc = pager_delmaster(pPager, zMaster);
    }
    sqlite3_free(zMaster);
  }

  /* The Pager.sectorSize variable may have been updated while rolling
  ** back a journal created by a process with a different sector size
  ** value. Reset it to the correct value for this process.
................................................................................
**
** Write the file descriptor into *fd.  Return SQLITE_OK on success or some
** other error code if we fail.
**
** The OS will automatically delete the temporary file when it is
** closed.
*/
static int sqlite3PagerOpentemp(
  sqlite3_vfs *pVfs, 
  sqlite3_file *pFile, 
  char *zNameOut
){
  int cnt = 8;
  int rc;

  int flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_EXCLUSIVE);

  char *zFree = 0;
  if( zNameOut==0 ){
    zFree = (char *)sqlite3_malloc(pVfs->mxPathname);
    if( !zFree ){
      return SQLITE_NOMEM;
    }
    zNameOut = zFree;
  }

#ifdef SQLITE_TEST
  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
#endif

  do{
    cnt--;

    sqlite3OsGetTempName(pVfs, zNameOut);
    rc = sqlite3OsOpen(pVfs, zNameOut, pFile, flags, 0);
    assert( rc!=SQLITE_OK || pFile->pMethods );
  }while( cnt>0 && rc!=SQLITE_OK && rc!=SQLITE_NOMEM );

  sqlite3_free(zFree);
  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
** the first call to sqlite3PagerGet() and is only held open until the
................................................................................
** automatically when it is closed.
**
** If zFilename is ":memory:" then all information is held in cache.
** It is never written to disk.  This can be used to implement an
** in-memory database.
*/
int sqlite3PagerOpen(
  sqlite3_vfs *pVfs,
  Pager **ppPager,         /* Return the Pager structure here */
  const char *zFilename,   /* Name of the database file to open */
  int nExtra,              /* Extra bytes append to each in-memory page */
  int flags                /* flags controlling this file */
){
  u8 *pPtr;
  Pager *pPager = 0;
  char *zFullPathname = 0;


  int rc = SQLITE_OK;
  int i;
  int tempFile = 0;
  int memDb = 0;
  int readOnly = 0;
  int useJournal = (flags & PAGER_OMIT_JOURNAL)==0;
  int noReadlock = (flags & PAGER_NO_READLOCK)!=0;

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  /* A malloc() cannot fail in sqlite3ThreadData() as one or more calls to 
  ** malloc() must have already been made by this thread before it gets
  ** to this point. This means the ThreadData must have been allocated already
  ** so that ThreadData.nAlloc can be set. It would be nice to assert
  ** that ThreadData.nAlloc is non-zero, but alas this breaks test cases 
  ** written to invoke the pager directly.
................................................................................
  /* We used to test if malloc() had already failed before proceeding. 
  ** But the way this function is used in SQLite means that can never
  ** happen. Furthermore, if the malloc-failed flag is already set, 
  ** either the call to sqlite3StrDup() or sqlite3_malloc() below will
  ** fail shortly and SQLITE_NOMEM returned anyway.
  */
  *ppPager = 0;

  /* Allocate memory for the pager structure */
  pPager = sqlite3MallocZero(
    sizeof(*pPager) +           /* Pager structure */
    pVfs->szOsFile * 3 +        /* The db, journal and stmt journal files */ 
    pVfs->mxPathname * 3 + 30   /* zFilename, zDirectory, zJournal */
  );
  if( !pPager ){
    return SQLITE_NOMEM;
  }
  pPtr = (u8 *)&pPager[1];
  pPager->fd = (sqlite3_file*)&pPtr[pVfs->szOsFile*0];
  pPager->jfd = (sqlite3_file*)&pPtr[pVfs->szOsFile*1];
  pPager->stfd = (sqlite3_file*)&pPtr[pVfs->szOsFile*2];
  pPager->zFilename = (char*)&pPtr[pVfs->szOsFile*3];
  pPager->zDirectory = &pPager->zFilename[pVfs->mxPathname];
  pPager->zJournal = &pPager->zDirectory[pVfs->mxPathname];
  pPager->pVfs = pVfs;

  /* Open the pager file and set zFullPathname to point at malloc()ed 
  ** memory containing the complete filename (i.e. including the directory).
  */
  if( zFilename && zFilename[0] ){
#ifndef SQLITE_OMIT_MEMORYDB
    if( strcmp(zFilename,":memory:")==0 ){
      memDb = 1;
      pPager->zFilename[0] = '\0';
    }else
#endif
    {
      rc = sqlite3OsFullPathname(pVfs, zFilename, pPager->zFilename);
      if( rc==SQLITE_OK ){
        if( strlen(pPager->zFilename)>(pVfs->mxPathname - strlen("-journal")) ){
          rc = SQLITE_CANTOPEN;
        }else{
          int flag = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
          int fout = 0;
          rc = sqlite3OsOpen(pVfs, pPager->zFilename, pPager->fd, flag, &fout);
          readOnly = (fout&SQLITE_OPEN_READONLY);
        }
      }
    }
  }else{
    rc = sqlite3PagerOpentemp(pVfs, pPager->fd, pPager->zFilename);



    if( rc==SQLITE_OK ){
      tempFile = 1;
    }
  }








  if( pPager && rc==SQLITE_OK ){
    pPager->pTmpSpace = (char *)sqlite3_malloc(SQLITE_DEFAULT_PAGE_SIZE);
  }



  /* If an error occured in either of the blocks above, free the memory 
  ** pointed to by zFullPathname, free the Pager structure and close the 
  ** file. Since the pager is not allocated there is no need to set 
  ** any Pager.errMask variables.
  */
  if( !pPager || !pPager->pTmpSpace ){
    sqlite3OsClose(pPager->fd);

    sqlite3_free(pPager);
    return ((rc==SQLITE_OK)?SQLITE_NOMEM:rc);
  }

  PAGERTRACE3("OPEN %d %s\n", FILEHANDLEID(fd), zFullPathname);
  IOTRACE(("OPEN %p %s\n", pPager, zFullPathname))

  /* Fill in Pager.zDirectory[] */
  memcpy(pPager->zDirectory, pPager->zFilename, pVfs->mxPathname);
  for(i=strlen(pPager->zDirectory); i>0 && pPager->zDirectory[i-1]!='/'; i--){}
  if( i>0 ) pPager->zDirectory[i-1] = 0;

  /* Fill in Pager.zJournal[] */
  memcpy(pPager->zJournal, pPager->zFilename, pVfs->mxPathname);
  memcpy(&pPager->zJournal[strlen(pPager->zJournal)], "-journal", 9);



  /* pPager->journalOpen = 0; */
  pPager->useJournal = useJournal && !memDb;
  pPager->noReadlock = noReadlock && readOnly;
  /* pPager->stmtOpen = 0; */
  /* pPager->stmtInUse = 0; */
  /* pPager->nRef = 0; */
  pPager->dbSize = memDb-1;
................................................................................
  /* pPager->needSync = 0; */
  pPager->noSync = pPager->tempFile || !useJournal;
  pPager->fullSync = (pPager->noSync?0:1);
  /* pPager->pFirst = 0; */
  /* pPager->pFirstSynced = 0; */
  /* pPager->pLast = 0; */
  pPager->nExtra = FORCE_ALIGNMENT(nExtra);
  assert(pPager->fd->pMethods||memDb);
  if( !memDb ){
    setSectorSize(pPager);
  }
  /* pPager->pBusyHandler = 0; */
  /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
  *ppPager = pPager;
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
................................................................................
  pager_reset(pPager);
  pagerUnlockAndRollback(pPager);
  enable_simulated_io_errors();
  PAGERTRACE2("CLOSE %d\n", PAGERID(pPager));
  IOTRACE(("CLOSE %p\n", pPager))
  assert( pPager->errCode || (pPager->journalOpen==0 && pPager->stmtOpen==0) );
  if( pPager->journalOpen ){
    sqlite3OsClose(pPager->jfd);
  }
  sqlite3_free(pPager->aInJournal);
  if( pPager->stmtOpen ){
    sqlite3OsClose(pPager->stfd);
  }
  sqlite3OsClose(pPager->fd);
  /* Temp files are automatically deleted by the OS
  ** if( pPager->tempFile ){
  **   sqlite3OsDelete(pPager->zFilename);
  ** }
  */

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
................................................................................
** A hot journal is one that needs to be played back.
**
** 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){
  sqlite3_vfs *pVfs = pPager->pVfs;
  if( !pPager->useJournal ) return 0;

  if( !sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS) ){
    return 0;
  }
  if( sqlite3OsCheckReservedLock(pPager->fd) ){
    return 0;
  }
  if( sqlite3PagerPagecount(pPager)==0 ){
    sqlite3OsDelete(pVfs, pPager->zJournal);
    return 0;
  }else{
    return 1;
  }
}

/*
................................................................................
  int i;

  /* If the the global mutex is held, this subroutine becomes a
  ** o-op; zero bytes of memory are freed.  This is because
  ** some of the code invoked by this function may also
  ** try to obtain the mutex, resulting in a deadlock.
  */
#if 0
  if( sqlite3OsInMutex(0) ){
    return 0;
  }
#endif

  /* Outermost loop runs for at most two iterations. First iteration we
  ** try to find memory that can be released without calling fsync(). Second
  ** iteration (which only runs if the first failed to free nReq bytes of
  ** memory) is permitted to call fsync(). This is of course much more 
  ** expensive.
  */
................................................................................
** checks for a hot-journal file. If one is found, an emergency rollback
** is performed immediately.
*/
static int pagerSharedLock(Pager *pPager){
  int rc = SQLITE_OK;

  if( pPager->state==PAGER_UNLOCK ){
    sqlite3_vfs *pVfs = pPager->pVfs;
    if( !MEMDB ){
      assert( pPager->nRef==0 );
      if( !pPager->noReadlock ){
        rc = pager_wait_on_lock(pPager, SHARED_LOCK);
        if( rc!=SQLITE_OK ){
          return pager_error(pPager, rc);
        }
................................................................................
        ** Open the journal for read/write access. This is because in 
        ** exclusive-access mode the file descriptor will be kept open and
        ** possibly used for a transaction later on. On some systems, the
        ** OsTruncate() call used in exclusive-access mode also requires
        ** a read/write file handle.
        */
        rc = SQLITE_BUSY;
        if( sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS) ){
          int fout = 0;
          int flags = SQLITE_OPEN_READWRITE;
          assert( !pPager->tempFile );

          rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, &fout);
          assert( rc!=SQLITE_OK || pPager->jfd->pMethods );

          if( fout&SQLITE_OPEN_READONLY ){
            rc = SQLITE_BUSY;
            sqlite3OsClose(pPager->jfd);
          }
        }
        if( rc!=SQLITE_OK ){
          pager_unlock(pPager);
          return SQLITE_BUSY;
        }
        pPager->journalOpen = 1;
................................................................................
** Create a journal file for pPager.  There should already be a RESERVED
** or EXCLUSIVE lock on the database file when this routine is called.
**
** Return SQLITE_OK if everything.  Return an error code and release the
** write lock if anything goes wrong.
*/
static int pager_open_journal(Pager *pPager){
  sqlite3_vfs *pVfs = pPager->pVfs;
  int flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_EXCLUSIVE|SQLITE_OPEN_CREATE);

  int rc;
  assert( !MEMDB );
  assert( pPager->state>=PAGER_RESERVED );
  assert( pPager->journalOpen==0 );
  assert( pPager->useJournal );
  assert( pPager->aInJournal==0 );
  sqlite3PagerPagecount(pPager);
  pPager->aInJournal = sqlite3MallocZero( pPager->dbSize/8 + 1 );
  if( pPager->aInJournal==0 ){
    rc = SQLITE_NOMEM;
    goto failed_to_open_journal;
  }


  if( pPager->tempFile ){
    flags |= SQLITE_OPEN_DELETEONCLOSE;
  }
  rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, 0);
  assert( rc!=SQLITE_OK || pPager->jfd->pMethods );
  pPager->journalOff = 0;
  pPager->setMaster = 0;
  pPager->journalHdr = 0;
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_NOMEM ){
      sqlite3OsDelete(pVfs, pPager->zJournal);
    }
    goto failed_to_open_journal;
  }
#if 0
  sqlite3OsSetFullSync(pPager->jfd, pPager->full_fsync);
  sqlite3OsSetFullSync(pPager->fd, pPager->full_fsync);
  sqlite3OsOpenDirectory(pPager->jfd, pPager->zDirectory);
................................................................................
  assert( pPager->stmtJSize == pPager->journalOff );
#endif
  pPager->stmtJSize = pPager->journalOff;
  pPager->stmtSize = pPager->dbSize;
  pPager->stmtHdrOff = 0;
  pPager->stmtCksum = pPager->cksumInit;
  if( !pPager->stmtOpen ){
    rc = sqlite3PagerOpentemp(pPager->pVfs, pPager->stfd, 0);
    if( rc ) goto stmt_begin_failed;
    pPager->stmtOpen = 1;
    pPager->stmtNRec = 0;
  }
  pPager->stmtInUse = 1;
  return SQLITE_OK;
 

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.  The page cache subsystem reads and writes a file a page
** at a time and provides a journal for rollback.
**
** @(#) $Id: pager.h,v 1.61 2007/05/08 21:45:28 drh Exp $
*/

#ifndef _PAGER_H_
#define _PAGER_H_

/*
** The type used to represent a page number.  The first page in a file
................................................................................
#define PAGER_LOCKINGMODE_NORMAL      0
#define PAGER_LOCKINGMODE_EXCLUSIVE   1

/*
** See source code comments for a detailed description of the following
** routines:
*/
int sqlite3PagerOpen(Pager **ppPager, const char *zFilename,
                     int nExtra, int flags);
void sqlite3PagerSetBusyhandler(Pager*, BusyHandler *pBusyHandler);
void sqlite3PagerSetDestructor(Pager*, void(*)(DbPage*,int));
void sqlite3PagerSetReiniter(Pager*, void(*)(DbPage*,int));
int sqlite3PagerSetPagesize(Pager*, int);
int sqlite3PagerMaxPageCount(Pager*, int);
int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);
void sqlite3PagerSetCachesize(Pager*, int);

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.  The page cache subsystem reads and writes a file a page
** at a time and provides a journal for rollback.
**
** @(#) $Id: pager.h,v 1.62 2007/08/17 15:53:37 danielk1977 Exp $
*/

#ifndef _PAGER_H_
#define _PAGER_H_

/*
** The type used to represent a page number.  The first page in a file
................................................................................
#define PAGER_LOCKINGMODE_NORMAL      0
#define PAGER_LOCKINGMODE_EXCLUSIVE   1

/*
** See source code comments for a detailed description of the following
** routines:
*/
int sqlite3PagerOpen(sqlite3_vfs *, Pager **ppPager, const char *, int, int);

void sqlite3PagerSetBusyhandler(Pager*, BusyHandler *pBusyHandler);
void sqlite3PagerSetDestructor(Pager*, void(*)(DbPage*,int));
void sqlite3PagerSetReiniter(Pager*, void(*)(DbPage*,int));
int sqlite3PagerSetPagesize(Pager*, int);
int sqlite3PagerMaxPageCount(Pager*, int);
int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);
void sqlite3PagerSetCachesize(Pager*, int);

**    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 1.144 2007/08/16 10:09:03 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/
................................................................................
        sqlite3VdbeSetNumCols(v, 1);
        sqlite3VdbeSetColName(v, 0, COLNAME_NAME, 
            "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] && !sqlite3OsIsDirWritable(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)
      ){

**    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 1.145 2007/08/17 15:53:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/
................................................................................
        sqlite3VdbeSetNumCols(v, 1);
        sqlite3VdbeSetColName(v, 0, COLNAME_NAME, 
            "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] 
       && !sqlite3OsAccess(db->pVfs, zRight, SQLITE_ACCESS_READWRITE) 
      ){
        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)
      ){

*************************************************************************
** 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 1.16 2007/01/05 14:38:56 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();
}

*************************************************************************
** 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 1.17 2007/08/17 15:53:37 danielk1977 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;
    sqlite3OsRandomness(sqlite3_find_vfs(0), 256, 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;
  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_PRNG));
  while( N-- ){
    *(zBuf++) = randomByte();
  }
  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_PRNG));
}

** 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 1.227 2007/08/17 01:14:38 drh 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++.
................................................................................
  void *pAppData;          /* Application context */
  int (*xOpen)(void *pAppData, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
  int (*xDelete)(void *pAppData, const char *zName);
  int (*xAccess)(void *pAppData, const char *zName, int flags);
  int (*xGetTempName)(void *pAppData, char *zOut);
  int (*xFullPathname)(void *pAppData, const char *zName, char *zOut);
  void *(*xDlOpen)(void *pAppData, char *zFilename);
  void (*xDlError)(void*, int nByte, char *zErrMsg);
  void *(*xDlSym)(void*, const char *zSymbol);
  void (*xDlclose)(void*);
  int (*xRandomness)(void *pAppData, int nByte, char *zOut);
  int (*xSleep)(void *pAppData, int microseconds);
  int (*xCurrentTime)(void *pAppData, double*);
  /* New fields may be appended in figure versions.  The iVersion
  ** value will increment whenever this happens. */
};





/*
** CAPI3REF: Enable Or Disable Extended Result Codes
**
** This routine enables or disables the
** [SQLITE_IOERR_READ | extended result codes] feature.
** By default, SQLite API routines return one of only 26 integer

** 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++.
................................................................................
  void *pAppData;          /* Application context */
  int (*xOpen)(void *pAppData, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
  int (*xDelete)(void *pAppData, const char *zName);
  int (*xAccess)(void *pAppData, const char *zName, int flags);
  int (*xGetTempName)(void *pAppData, char *zOut);
  int (*xFullPathname)(void *pAppData, const char *zName, char *zOut);
  void *(*xDlOpen)(void *pAppData, const char *zFilename);
  void (*xDlError)(void *pAppData, int nByte, char *zErrMsg);
  void *(*xDlSym)(void*, const char *zSymbol);
  void (*xDlClose)(void*);
  int (*xRandomness)(void *pAppData, int nByte, char *zOut);
  int (*xSleep)(void *pAppData, int microseconds);
  int (*xCurrentTime)(void *pAppData, double*);
  /* New fields may be appended in figure versions.  The iVersion
  ** value will increment whenever this happens. */
};

#define SQLITE_ACCESS_EXISTS    0
#define SQLITE_ACCESS_READWRITE 1
#define SQLITE_ACCESS_READONLY  2

/*
** CAPI3REF: Enable Or Disable Extended Result Codes
**
** This routine enables or disables the
** [SQLITE_IOERR_READ | extended result codes] feature.
** By default, SQLite API routines return one of only 26 integer

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.590 2007/08/17 01:14:38 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
#include "sqliteLimit.h"


#if defined(SQLITE_TCL) || defined(TCLSH)
................................................................................
/*
** The mutex subsystem provides a handfull of static mutexes
** that are identified by small positive integers.  The following
** macros give symbolic names to those integers.
*/
#define SQLITE_MUTEX_MEM      1    /* Used by the memory allocator */
#define SQLITE_MUTEX_PRNG     2    /* Used by pseudorandom generator */
#define SQLITE_MUTEX_CACHE    3    /* Used by shared cache */
#define SQLITE_MUTEX_STATIC_MAX 3

/*
** Macros to determine whether the machine is big or little endian,
** evaluated at runtime.
*/
extern const int sqlite3one;

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.591 2007/08/17 15:53:37 danielk1977 Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
#include "sqliteLimit.h"


#if defined(SQLITE_TCL) || defined(TCLSH)
................................................................................
/*
** The mutex subsystem provides a handfull of static mutexes
** that are identified by small positive integers.  The following
** macros give symbolic names to those integers.
*/
#define SQLITE_MUTEX_MEM      1    /* Used by the memory allocator */
#define SQLITE_MUTEX_PRNG     2    /* Used by pseudorandom generator */
#define SQLITE_MUTEX_GLOBAL   3    /* Used by global variables */
#define SQLITE_MUTEX_STATIC_MAX 3

/*
** Macros to determine whether the machine is big or little endian,
** evaluated at runtime.
*/
extern const int sqlite3one;

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.263 2007/08/17 01:14:38 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................
  if( Tcl_GetIntFromObj(interp, objv[2], &col) ) return TCL_ERROR;

  Tcl_SetObjResult(interp, Tcl_NewIntObj(xFunc(pStmt, col)));
  return TCL_OK;
}

#ifndef SQLITE_OMIT_DISKIO

/*
** Usage:  sqlite3OsOpenReadWrite <filename>
*/
static int test_sqlite3OsOpenReadWrite(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
................................................................................
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)t1ErrorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  Tcl_AppendResult(interp, zFile, 0);
  return TCL_OK;
}

#endif

/*
** Usage:  sqlite_set_magic  DB  MAGIC-NUMBER
**
** Set the db->magic value.  This is used to test error recovery logic.
*/
................................................................................
#endif
     { "sqlite3_create_collation_v2", test_create_collation_v2, 0 },
     { "sqlite3_global_recover",     test_global_recover, 0   },
     { "working_64bit_int",          working_64bit_int,   0   },

     /* Functions from os.h */
#ifndef SQLITE_OMIT_DISKIO

     { "sqlite3OsOpenReadWrite",test_sqlite3OsOpenReadWrite, 0 },
     { "sqlite3OsClose",        test_sqlite3OsClose, 0 },
     { "sqlite3OsLock",         test_sqlite3OsLock, 0 },
     { "sqlite3OsTempFileName", test_sqlite3OsTempFileName, 0 },
   
     /* Custom test interfaces */
     { "sqlite3OsUnlock",         test_sqlite3OsUnlock, 0    },

#endif
#ifndef SQLITE_OMIT_UTF16
     { "add_test_collate",        test_collate, 0            },
     { "add_test_collate_needed", test_collate_needed, 0     },
     { "add_test_function",       test_function, 0           },
#endif
     { "sqlite3_test_errstr",     test_errstr, 0             },

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.264 2007/08/17 15:53:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................
  if( Tcl_GetIntFromObj(interp, objv[2], &col) ) return TCL_ERROR;

  Tcl_SetObjResult(interp, Tcl_NewIntObj(xFunc(pStmt, col)));
  return TCL_OK;
}

#ifndef SQLITE_OMIT_DISKIO
#if 0
/*
** Usage:  sqlite3OsOpenReadWrite <filename>
*/
static int test_sqlite3OsOpenReadWrite(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
................................................................................
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)t1ErrorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  Tcl_AppendResult(interp, zFile, 0);
  return TCL_OK;
}
#endif
#endif

/*
** Usage:  sqlite_set_magic  DB  MAGIC-NUMBER
**
** Set the db->magic value.  This is used to test error recovery logic.
*/
................................................................................
#endif
     { "sqlite3_create_collation_v2", test_create_collation_v2, 0 },
     { "sqlite3_global_recover",     test_global_recover, 0   },
     { "working_64bit_int",          working_64bit_int,   0   },

     /* Functions from os.h */
#ifndef SQLITE_OMIT_DISKIO
#if 0
     { "sqlite3OsOpenReadWrite",test_sqlite3OsOpenReadWrite, 0 },
     { "sqlite3OsClose",        test_sqlite3OsClose, 0 },
     { "sqlite3OsLock",         test_sqlite3OsLock, 0 },
     { "sqlite3OsTempFileName", test_sqlite3OsTempFileName, 0 },
   
     /* Custom test interfaces */
     { "sqlite3OsUnlock",         test_sqlite3OsUnlock, 0    },
#endif
#endif
#ifndef SQLITE_OMIT_UTF16
     { "add_test_collate",        test_collate, 0            },
     { "add_test_collate_needed", test_collate_needed, 0     },
     { "add_test_function",       test_function, 0           },
#endif
     { "sqlite3_test_errstr",     test_errstr, 0             },

**    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 1.45 2007/08/16 10:09:03 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
  char zBuf[100];
  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " FILENAME N-PAGE\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[2], &nPage) ) return TCL_ERROR;
  rc = sqlite3PagerOpen(&pPager, argv[1], 0, 0);
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, errorName(rc), 0);
    return TCL_ERROR;
  }
  sqlite3PagerSetCachesize(pPager, nPage);
  sqlite3PagerSetPagesize(pPager, test_pagesize);
  sqlite3_snprintf(sizeof(zBuf),zBuf,"%p",pPager);
................................................................................
*/
static int fake_big_file(
  void *NotUsed,
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int argc,              /* Number of arguments */
  const char **argv      /* Text of each argument */
){



  int rc;
  int n;
  i64 offset;
  sqlite3_file *fd = 0;
  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 = sqlite3OsOpenReadWrite(argv[2], &fd, &readOnly);


  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  offset = n;
  offset *= 1024*1024;
  rc = sqlite3OsWrite(fd, "Hello, World!", 14, offset);
  sqlite3OsClose(&fd);
  if( rc ){
    Tcl_AppendResult(interp, "write failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}
#endif

**    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 1.46 2007/08/17 15:53:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
  char zBuf[100];
  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " FILENAME N-PAGE\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[2], &nPage) ) return TCL_ERROR;
  rc = sqlite3PagerOpen(sqlite3_find_vfs(0), &pPager, argv[1], 0, 0);
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, errorName(rc), 0);
    return TCL_ERROR;
  }
  sqlite3PagerSetCachesize(pPager, nPage);
  sqlite3PagerSetPagesize(pPager, test_pagesize);
  sqlite3_snprintf(sizeof(zBuf),zBuf,"%p",pPager);
................................................................................
*/
static int fake_big_file(
  void *NotUsed,
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int argc,              /* Number of arguments */
  const char **argv      /* Text of each argument */
){
  sqlite3_vfs *pVfs;
  sqlite3_file *fd = 0;
  int flags = SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE;
  int rc;
  int n;
  i64 offset;


  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;

  pVfs = sqlite3_find_vfs(0);
  rc = sqlite3OsOpenMalloc(pVfs, argv[2], &fd, flags);
  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  offset = n;
  offset *= 1024*1024;
  rc = sqlite3OsWrite(fd, "Hello, World!", 14, offset);
  sqlite3OsCloseFree(fd);
  if( rc ){
    Tcl_AppendResult(interp, "write failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}
#endif

  const u8 *zBuf,
  int nBuf
){
  WriteBuffer *pNew;

  assert((zBuf && nBuf) || (!nBuf && !zBuf));

  pNew = (WriteBuffer *)sqlite3_malloc(sizeof(WriteBuffer) + nBuf);
  pNew->iOffset = iOffset;
  pNew->nBuf = nBuf;
  pNew->pFile = (CrashFile *)pFile;
  if( zBuf ){
    pNew->zBuf = (u8 *)&pNew[1];
    memcpy(pNew->zBuf, zBuf, nBuf);
  }
................................................................................
*/
static int crashParamsObjCmd(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){

  int i;

  int iDelay;
  const char *zCrashFile;
  int nCrashFile;

  int iDc = 0;
  int iSectorSize = 0;
  int setSectorsize = 0;
................................................................................
    { "sequential",  SQLITE_IOCAP_SEQUENTIAL  },
    { "safe_append", SQLITE_IOCAP_SAFE_APPEND },
    { 0, 0 }
  };
  
  if( objc<3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "?OPTIONS? DELAY CRASHFILE");
    return TCL_ERROR;
  }



  zCrashFile = sqlite3OsFullPathname(Tcl_GetString(objv[objc-1]));
  nCrashFile = strlen(zCrashFile);
  if( nCrashFile>=sizeof(g.zCrashFile) ){
    Tcl_AppendResult(interp, "Filename is too long: \"", zCrashFile, "\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetIntFromObj(interp, objv[objc-2], &iDelay) ){
    return TCL_ERROR;
  }

  for(i=1; i<(objc-2); i+=2){
    int nOpt;
    char *zOpt = Tcl_GetStringFromObj(objv[i], &nOpt);

    if( (nOpt>11 || nOpt<2 || strncmp("-sectorsize", zOpt, nOpt)) 
     && (nOpt>16 || nOpt<2 || strncmp("-characteristics", zOpt, nOpt))
    ){
      Tcl_AppendResult(interp, 
        "Bad option: \"", zOpt, 
        "\" - must be \"-characteristics\" or \"-sectorsize\"", 0
      );
      return TCL_ERROR;
    }
    if( i==objc-3 ){
      Tcl_AppendResult(interp, "Option requires an argument: \"", zOpt, "\"",0);
      return TCL_ERROR;
    }

    if( zOpt[1]=='s' ){
      if( Tcl_GetIntFromObj(interp, objv[i+1], &iSectorSize) ){
        return TCL_ERROR;
      }
      setSectorsize = 1;
    }else{
      int j;
      Tcl_Obj **apObj;
      int nObj;
      if( Tcl_ListObjGetElements(interp, objv[i+1], &nObj, &apObj) ){
        return TCL_ERROR;
      }
      for(j=0; j<nObj; j++){
        int rc;
        int iChoice;
        Tcl_Obj *pFlag = Tcl_DuplicateObj(apObj[j]);
        Tcl_IncrRefCount(pFlag);
        Tcl_UtfToLower(Tcl_GetString(pFlag));
 
        rc = Tcl_GetIndexFromObjStruct(
            interp, pFlag, aFlag, sizeof(aFlag[0]), "no such flag", 0, &iChoice
        );
        Tcl_DecrRefCount(pFlag);
        if( rc ){
          return TCL_ERROR;
        }

        iDc |= aFlag[iChoice].iValue;
      }
      setDeviceChar = 1;
    }
  }
................................................................................
    g.iDeviceCharacteristics = iDc;
  }
  if( setSectorsize ){
    g.iSectorSize = iSectorSize;
  }
  g.iCrash = iDelay;
  memcpy(g.zCrashFile, zCrashFile, nCrashFile+1);


  sqlite3CrashTestEnable = 1;
  return TCL_OK;




}

#endif /* SQLITE_OMIT_DISKIO */

/*
** This procedure registers the TCL procedures defined in this file.
*/

  const u8 *zBuf,
  int nBuf
){
  WriteBuffer *pNew;

  assert((zBuf && nBuf) || (!nBuf && !zBuf));

  pNew = (WriteBuffer *)sqlite3MallocZero(sizeof(WriteBuffer) + nBuf);
  pNew->iOffset = iOffset;
  pNew->nBuf = nBuf;
  pNew->pFile = (CrashFile *)pFile;
  if( zBuf ){
    pNew->zBuf = (u8 *)&pNew[1];
    memcpy(pNew->zBuf, zBuf, nBuf);
  }
................................................................................
*/
static int crashParamsObjCmd(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3_vfs *pVfs;
  int i;

  int iDelay;
  const char *zCrashFile;
  int nCrashFile;

  int iDc = 0;
  int iSectorSize = 0;
  int setSectorsize = 0;
................................................................................
    { "sequential",  SQLITE_IOCAP_SEQUENTIAL  },
    { "safe_append", SQLITE_IOCAP_SAFE_APPEND },
    { 0, 0 }
  };
  
  if( objc<3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "?OPTIONS? DELAY CRASHFILE");
    goto error;
  }

  pVfs = sqlite3_find_vfs(0);
  zCrashFile = sqlite3_malloc(pVfs->mxPathname);
  sqlite3OsFullPathname(pVfs, Tcl_GetString(objv[objc-1]), zCrashFile);
  nCrashFile = strlen(zCrashFile);
  if( nCrashFile>=sizeof(g.zCrashFile) ){
    Tcl_AppendResult(interp, "Filename is too long: \"", zCrashFile, "\"", 0);
    goto error;
  }
  if( Tcl_GetIntFromObj(interp, objv[objc-2], &iDelay) ){
    goto error;
  }

  for(i=1; i<(objc-2); i+=2){
    int nOpt;
    char *zOpt = Tcl_GetStringFromObj(objv[i], &nOpt);

    if( (nOpt>11 || nOpt<2 || strncmp("-sectorsize", zOpt, nOpt)) 
     && (nOpt>16 || nOpt<2 || strncmp("-characteristics", zOpt, nOpt))
    ){
      Tcl_AppendResult(interp, 
        "Bad option: \"", zOpt, 
        "\" - must be \"-characteristics\" or \"-sectorsize\"", 0
      );
      goto error;
    }
    if( i==objc-3 ){
      Tcl_AppendResult(interp, "Option requires an argument: \"", zOpt, "\"",0);
      goto error;
    }

    if( zOpt[1]=='s' ){
      if( Tcl_GetIntFromObj(interp, objv[i+1], &iSectorSize) ){
        goto error;
      }
      setSectorsize = 1;
    }else{
      int j;
      Tcl_Obj **apObj;
      int nObj;
      if( Tcl_ListObjGetElements(interp, objv[i+1], &nObj, &apObj) ){
        goto error;
      }
      for(j=0; j<nObj; j++){
        int rc;
        int iChoice;
        Tcl_Obj *pFlag = Tcl_DuplicateObj(apObj[j]);
        Tcl_IncrRefCount(pFlag);
        Tcl_UtfToLower(Tcl_GetString(pFlag));
 
        rc = Tcl_GetIndexFromObjStruct(
            interp, pFlag, aFlag, sizeof(aFlag[0]), "no such flag", 0, &iChoice
        );
        Tcl_DecrRefCount(pFlag);
        if( rc ){
          goto error;
        }

        iDc |= aFlag[iChoice].iValue;
      }
      setDeviceChar = 1;
    }
  }
................................................................................
    g.iDeviceCharacteristics = iDc;
  }
  if( setSectorsize ){
    g.iSectorSize = iSectorSize;
  }
  g.iCrash = iDelay;
  memcpy(g.zCrashFile, zCrashFile, nCrashFile+1);

  sqlite3_free(zCrashFile);
  sqlite3CrashTestEnable = 1;
  return TCL_OK;

error:
  sqlite3_free(zCrashFile);
  return TCL_ERROR;
}

#endif /* SQLITE_OMIT_DISKIO */

/*
** This procedure registers the TCL procedures defined in this file.
*/

**
** 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 1.641 2007/08/16 10:09:03 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include <math.h>
#include "vdbeInt.h"

................................................................................
  }
  p->resOnStack = 0;
  db->busyHandler.nBusy = 0;
  CHECK_FOR_INTERRUPT;
  sqlite3VdbeIOTraceSql(p);
#ifdef SQLITE_DEBUG
  if( (p->db->flags & SQLITE_VdbeListing)!=0
    || sqlite3OsFileExists("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( sqlite3OsFileExists("vdbe_trace") ){
    p->trace = stdout;
  }
#endif
  for(pc=p->pc; rc==SQLITE_OK; pc++){
    assert( pc>=0 && pc<p->nOp );
    assert( pTos<=&p->aStack[pc] );
    if( db->mallocFailed ) goto no_mem;
................................................................................
    if( p->trace ){
      if( pc==0 ){
        printf("VDBE Execution Trace:\n");
        sqlite3VdbePrintSql(p);
      }
      sqlite3VdbePrintOp(p->trace, pc, pOp);
    }
    if( p->trace==0 && pc==0 && sqlite3OsFileExists("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.

**
** 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 1.642 2007/08/17 15:53:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include <math.h>
#include "vdbeInt.h"

................................................................................
  }
  p->resOnStack = 0;
  db->busyHandler.nBusy = 0;
  CHECK_FOR_INTERRUPT;
  sqlite3VdbeIOTraceSql(p);
#ifdef SQLITE_DEBUG
  if( (p->db->flags & SQLITE_VdbeListing)!=0
    || sqlite3OsAccess(db->pVfs, "vdbe_explain", SQLITE_ACCESS_EXISTS)
  ){
    int i;
    printf("VDBE Program Listing:\n");
    sqlite3VdbePrintSql(p);
    for(i=0; i<p->nOp; i++){
      sqlite3VdbePrintOp(stdout, i, &p->aOp[i]);
    }
  }
  if( sqlite3OsAccess(db->pVfs, "vdbe_trace", SQLITE_ACCESS_EXISTS) ){
    p->trace = stdout;
  }
#endif
  for(pc=p->pc; rc==SQLITE_OK; pc++){
    assert( pc>=0 && pc<p->nOp );
    assert( pTos<=&p->aStack[pc] );
    if( db->mallocFailed ) goto no_mem;
................................................................................
    if( p->trace ){
      if( pc==0 ){
        printf("VDBE Execution Trace:\n");
        sqlite3VdbePrintSql(p);
      }
      sqlite3VdbePrintOp(p->trace, pc, pOp);
    }
    if( p->trace==0 && pc==0 
     && sqlite3OsAccess(db->pVfs, "vdbe_sqltrace", SQLITE_ACCESS_EXISTS) ){
      sqlite3VdbePrintSql(p);
    }
#endif
      

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

      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);
  }

      if( sqlite3SafetyOn(db) ){
        p->rc = SQLITE_MISUSE;
        return SQLITE_MISUSE;
      }
    }
    if( db->xProfile && !db->init.busy ){
      double rNow;
      sqlite3OsCurrentTime(db->pVfs, &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(db->pVfs, &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);
  }

  /* The complex case - There is a multi-file write-transaction active.
  ** This requires a master journal file to ensure the transaction is
  ** committed atomicly.
  */
#ifndef SQLITE_OMIT_DISKIO
  else{


    int needSync = 0;
    char *zMaster = 0;   /* File-name for the master journal */
    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
    sqlite3_file *master = 0;
    i64 offset = 0;

    /* Select a master journal file name */
    do {
      u32 random;
      sqlite3_free(zMaster);
      sqlite3Randomness(sizeof(random), &random);
      zMaster = sqlite3MPrintf(db, "%s-mj%08X", zMainFile, random&0x7fffffff);
      if( !zMaster ){
        return SQLITE_NOMEM;
      }
    }while( sqlite3OsFileExists(zMaster) );

    /* Open the master journal. */
    rc = sqlite3OsOpenExclusive(zMaster, &master, 0);

    if( rc!=SQLITE_OK ){
      sqlite3_free(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
    ** and delete the master journal file. All the individual journal files
    ** still have 'null' as the master journal pointer, so they will roll
................................................................................
      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, offset);
        offset += strlen(zFile)+1;
        if( rc!=SQLITE_OK ){
          sqlite3OsClose(&master);
          sqlite3OsDelete(zMaster);
          sqlite3_free(zMaster);

          return rc;
        }
      }
    }


    /* Sync the master journal file. Before doing this, open the directory
................................................................................
    */
    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        rc = sqlite3BtreeCommitPhaseOne(pBt, zMaster);
      }
    }
    sqlite3OsClose(&master);
    if( rc!=SQLITE_OK ){
      sqlite3_free(zMaster);

      return rc;
    }

    /* 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 = sqlite3OsDelete(zMaster);
    sqlite3_free(zMaster);

    zMaster = 0;

    if( rc ){
      return rc;
    }

    rc = sqlite3OsSyncDirectory(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.

  /* The complex case - There is a multi-file write-transaction active.
  ** This requires a master journal file to ensure the transaction is
  ** committed atomicly.
  */
#ifndef SQLITE_OMIT_DISKIO
  else{
    sqlite3_vfs *pVfs = db->pVfs;
    int flag = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_EXCLUSIVE);
    int needSync = 0;
    char *zMaster = 0;   /* File-name for the master journal */
    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
    sqlite3_file *pMaster = 0;
    i64 offset = 0;

    /* Select a master journal file name */
    do {
      u32 random;
      sqlite3_free(zMaster);
      sqlite3Randomness(sizeof(random), &random);
      zMaster = sqlite3MPrintf(db, "%s-mj%08X", zMainFile, random&0x7fffffff);
      if( !zMaster ){
        return SQLITE_NOMEM;
      }
    }while( sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS) );

    /* Open the master journal. */
    pMaster = sqlite3_malloc(pVfs->szOsFile);
    rc = sqlite3OsOpen(pVfs, zMaster, pMaster, flag, 0);
    if( rc!=SQLITE_OK ){
      sqlite3_free(zMaster);
      sqlite3_free(pMaster);
      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
    ** and delete the master journal file. All the individual journal files
    ** still have 'null' as the master journal pointer, so they will roll
................................................................................
      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(pMaster, zFile, strlen(zFile)+1, offset);
        offset += strlen(zFile)+1;
        if( rc!=SQLITE_OK ){
          sqlite3OsClose(pMaster);
          sqlite3OsDelete(pVfs, zMaster);
          sqlite3_free(zMaster);
          sqlite3_free(pMaster);
          return rc;
        }
      }
    }


    /* Sync the master journal file. Before doing this, open the directory
................................................................................
    */
    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        rc = sqlite3BtreeCommitPhaseOne(pBt, zMaster);
      }
    }
    sqlite3OsClose(pMaster);
    if( rc!=SQLITE_OK ){
      sqlite3_free(zMaster);
      sqlite3_free(pMaster);
      return rc;
    }

    /* 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 = sqlite3OsDelete(pVfs, zMaster);
    sqlite3_free(zMaster);
    sqlite3_free(pMaster);
    zMaster = 0;
    pMaster = 0;
    if( rc ){
      return rc;
    }
#if 0
    rc = sqlite3OsSyncDirectory(zMainFile);
#endif
    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.