SQLite

    if( rc==SQLITE_DONE 
     && (rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1))==SQLITE_OK
    ){
      int nDestTruncate;
  
      if( p->pDestDb ){
        sqlite3ResetInternalSchema(p->pDestDb, -1);
        }
      
      if( destMode==PAGER_JOURNALMODE_WAL ){
          /* This call cannot fail. The success of the BtreeUpdateMeta()
                    ** method above indicates that a write transaction has been opened
                    ** and page 1 is already dirty. Therefore this always succeeds.
                    */
          TESTONLY(int rc2 =) sqlite3BtreeSetVersion(p->pDest, 2);
          assert( rc2==SQLITE_OK );
      }

      /* Set nDestTruncate to the final number of pages in the destination
      ** database. The complication here is that the destination page
      ** size may be different to the source page size. 
      **
      ** If the source page size is smaller than the destination page size, 

** "write version" (single byte at byte offset 19) fields in the database
** header to iVersion.
*/
int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
  BtShared *pBt = pBtree->pBt;
  int rc;                         /* Return code */
 

  assert( iVersion==1 || iVersion==2 );

  /* If setting the version fields to 1, do not automatically open the
  ** WAL connection, even if the version fields are currently set to 2.
  */
  pBt->doNotUseWAL = (u8)(iVersion==1);

    zFilename += sqlite3Strlen30(zFilename) + 1;
    if( x==0 ) return zFilename;
    zFilename += sqlite3Strlen30(zFilename) + 1;
  }
  return 0;
}

#if (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__)


#include "sqlite3_private.h"



















































/* 






















** Testing a file path for sqlite locks held by a process ID. 
** Returns SQLITE_LOCKSTATE_ON if locks are present on path
** that would prevent writing to the database.



*/
int _sqlite3_lockstate(const char *path, pid_t pid){






  sqlite3 *db = NULL;




  




  if( sqlite3_open_v2(path, &db, SQLITE_OPEN_READONLY, NULL) == SQLITE_OK ){





    LockstatePID lockstate = {pid, -1};










    sqlite3_file_control(db, NULL, SQLITE_FCNTL_LOCKSTATE_PID, &lockstate);
    sqlite3_close(db);









    int state = lockstate.state;




    return state;
  }
  return SQLITE_LOCKSTATE_ERROR;
}

#endif /* SQLITE_ENABLE_APPLE_SPI */

#if (!defined(__APPLE__))

#define SQLITE_MALLOC(x) malloc(x)
#define SQLITE_FREE(x) free(x)
#define SQLITE_REALLOC(x,y) realloc((x),(y))


#else


#include <sys/sysctl.h>
#include <malloc/malloc.h>
#include <libkern/OSAtomic.h>

static malloc_zone_t* _sqliteZone_;

#define SQLITE_MALLOC(x) malloc_zone_malloc(_sqliteZone_, (x))
#define SQLITE_FREE(x) malloc_zone_free(_sqliteZone_, (x));
#define SQLITE_REALLOC(x,y) malloc_zone_realloc(_sqliteZone_, (x), (y))
#define SQLITE_MALLOCSIZE(x) (_sqliteZone_ ? _sqliteZone_->size(_sqliteZone_,x) : malloc_size(x))

#endif

/*
** Like malloc(), but remember the size of the allocation
** so that we can find it later using sqlite3MemSize().
**
** For this low-level routine, we are guaranteed that nByte>0 because
** cases of nByte<=0 will be intercepted and dealt with by higher level
** routines.
*/
static void *sqlite3MemMalloc(int nByte){
  sqlite3_int64 *p;
  assert( nByte>0 );
  nByte = ROUND8(nByte);
#ifndef SQLITE_MALLOCSIZE
  p = SQLITE_MALLOC( nByte + 8 );
  if( p ){
    p[0] = nByte;
    p++;
  }else{
    testcase( sqlite3GlobalConfig.xLog!=0 );
    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes of memory", nByte);
  }
#else
  p = SQLITE_MALLOC( nByte );
  if( !p ){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes of memory", nByte);
  }
#endif
  return (void *)p;
}

/*
** Like free() but works for allocations obtained from sqlite3MemMalloc()
** or sqlite3MemRealloc().
**
** For this low-level routine, we already know that pPrior!=0 since
** cases where pPrior==0 will have been intecepted and dealt with
** by higher-level routines.
*/
static void sqlite3MemFree(void *pPrior){
  sqlite3_int64 *p = (sqlite3_int64*)pPrior;
  assert( pPrior!=0 );
#ifndef SQLITE_MALLOCSIZE
  p--;
#endif
  SQLITE_FREE(p);
}

/*
** Report the allocated size of a prior return from xMalloc()
** or xRealloc().
*/
static int sqlite3MemSize(void *pPrior){
#ifndef SQLITE_MALLOCSIZE
  sqlite3_int64 *p;
  if( pPrior==0 ) return 0;
  p = (sqlite3_int64*)pPrior;
  p--;
  return (int)p[0];
#else
  return (int)SQLITE_MALLOCSIZE(pPrior);
#endif
}

/*
** Like realloc().  Resize an allocation previously obtained from
** sqlite3MemMalloc().
**
** For this low-level interface, we know that pPrior!=0.  Cases where
** pPrior==0 while have been intercepted by higher-level routine and
** redirected to xMalloc.  Similarly, we know that nByte>0 becauses
** cases where nByte<=0 will have been intercepted by higher-level
** routines and redirected to xFree.
*/
static void *sqlite3MemRealloc(void *pPrior, int nByte){
  sqlite3_int64 *p = (sqlite3_int64*)pPrior;
  assert( pPrior!=0 && nByte>0 );
  assert( nByte==ROUND8(nByte) ); /* EV: R-46199-30249 */
#ifndef SQLITE_MALLOCSIZE
  p--;
  p = SQLITE_REALLOC(p, nByte+8 );
  if( p ){
    p[0] = nByte;
    p++;
  }else{
     testcase( sqlite3GlobalConfig.xLog!=0 );
     sqlite3_log(SQLITE_NOMEM,
       "failed memory resize %u to %u bytes",
       sqlite3MemSize(pPrior), nByte);
  }
#else
  p = SQLITE_REALLOC(p, nByte );
  if( !p ){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    sqlite3_log(SQLITE_NOMEM,
      "failed memory resize %u to %u bytes",
      sqlite3MemSize(pPrior), nByte);
  }
#endif
  return (void*)p;
}

/*
** Round up a request size to the next valid allocation size.
*/
static int sqlite3MemRoundup(int n){

  char aPadding[32];
#endif
};

/*
** Allowed values for the unixFile.ctrlFlags bitmask:
*/
#define UNIXFILE_EXCL        0x01     /* Connections from one process only */
#define UNIXFILE_RDONLY      0x02     /* Connection is read only */
#define UNIXFILE_PERSIST_WAL 0x04     /* Persistent WAL mode */

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

/*

  unixLeaveMutex();
  OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved));

  *pResOut = reserved;
  return rc;
}

static int _unixFileLock(unixFile *pFile, struct flock *pLock, int retry);

/*
** Attempt to set a system-lock on the file pFile.  The lock is 
** described by pLock.
**
** If the pFile was opened read/write from unix-excl, then the only lock
** ever obtained is an exclusive lock, and it is obtained exactly once
** the first time any lock is attempted.  All subsequent system locking
** operations become no-ops.  Locking operations still happen internally,
** in order to coordinate access between separate database connections
** within this process, but all of that is handled in memory and the
** operating system does not participate.
**
** This function is a pass-through to fcntl(F_SETLK) if pFile is using
** any VFS other than "unix-excl" or if pFile is opened on "unix-excl"
** and is read-only.
**
** Zero is returned if the call completes successfully, or -1 if a call
** to fcntl() fails. In this case, errno is set appropriately (by fcntl()).
*/
static int unixFileLock(unixFile *pFile, struct flock *pLock){
  return _unixFileLock(pFile, pLock, 0);
}

static int unixFileLock2(unixFile *pFile, struct flock *pLock){
  return _unixFileLock(pFile, pLock, 10);
}

static int _unixFileLock(unixFile *pFile, struct flock *pLock, int retry) {
  int rc = 0;
  unixInodeInfo *pInode = pFile->pInode;
  assert( unixMutexHeld() );
  assert( pInode!=0 );
  if( ((pFile->ctrlFlags & UNIXFILE_EXCL)!=0 || pInode->bProcessLock)
   && ((pFile->ctrlFlags & UNIXFILE_RDONLY)==0)
  ){
    if( pInode->bProcessLock==0 ){

      if( rc<0 ) return rc;
      pInode->bProcessLock = 1;
      pInode->nLock++;
    }else{
      rc = 0;
    }
  }else{
    int i = 0;                      
    do {
      rc = osFcntl(pFile->h, F_SETLK, pLock);
      if (rc && retry) {
        usleep(100 * (++i));
      }
    } while (!rc && retry--);
  }
  return rc;
}

/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:

      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
    }

    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( unixFileLock2(pFile, &lock) && rc==SQLITE_OK ){
      /* This could happen with a network mount */
      tErrno = errno;
#if OSLOCKING_CHECK_BUSY_IOERR
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); 
#else
      rc = SQLITE_IOERR_UNLOCK; 
#endif

    ** write lock until the rest is covered by a read lock:
    **  1:   [WWWWW]
    **  2:   [....W]
    **  3:   [RRRRW]
    **  4:   [RRRR.]
    */
    if( eFileLock==SHARED_LOCK ){
      int tErrno;               /* Error code from system call errors */

#if !defined(__APPLE__) || !SQLITE_ENABLE_LOCKING_STYLE
      (void)handleNFSUnlock;
      assert( handleNFSUnlock==0 );
#endif
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
      if( handleNFSUnlock ){

        off_t divSize = SHARED_SIZE - 1;
        
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( unixFileLock2(pFile, &lock)==(-1) ){
          tErrno = errno;
#if OSLOCKING_CHECK_BUSY_IOERR
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
#else
          rc = SQLITE_IOERR_UNLOCK;
#endif
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( unixFileLock2(pFile, &lock)==(-1) ){
          tErrno = errno;
#if OSLOCKING_CHECK_BUSY_IOERR
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
#else
          rc = SQLITE_IOERR_UNLOCK;
#endif
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST+divSize;
        lock.l_len = SHARED_SIZE-divSize;
        if( unixFileLock2(pFile, &lock)==(-1) ){
          tErrno = errno;
#if OSLOCKING_CHECK_BUSY_IOERR
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
#else
          rc = SQLITE_IOERR_UNLOCK;
#endif
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
      }else
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
      {
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        if( unixFileLock2(pFile, &lock) ){

          tErrno = errno;
#if OSLOCKING_CHECK_BUSY_IOERR
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);



#else
          /* In theory, the call to unixFileLock() cannot fail because another
          ** process is holding an incompatible lock. If it does, this 
          ** indicates that the other process is not following the locking
          ** protocol. If this happens, return SQLITE_IOERR_RDLOCK. Returning
          ** SQLITE_BUSY would confuse the upper layer (in practice it causes 
          ** an assert to fail). */ 
          rc = SQLITE_IOERR_RDLOCK;
          pFile->lastErrno = tErrno;
#endif
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( unixFileLock2(pFile, &lock)==0 ){
      pInode->eFileLock = SHARED_LOCK;
    }else{
#if OSLOCKING_CHECK_BUSY_IOERR
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;

    if( pInode->nShared==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( unixFileLock2(pFile, &lock)==0 ){
        pInode->eFileLock = NO_LOCK;
      }else{
#if OSLOCKING_CHECK_BUSY_IOERR
        tErrno = errno;
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;

#if (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__)
#include "sqlite3_private.h"
#include <copyfile.h>
static int getDbPathForUnixFile(unixFile *pFile, char *dbPath);
#endif
static int isProxyLockingMode(unixFile *);

#if (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__)
static int unixTruncateDatabase(unixFile *, int);

static int unixInvalidateSupportFiles(unixFile *, int);

static int unixReplaceDatabase(unixFile *pFile, sqlite3 *srcdb) {
  sqlite3_file *id = (sqlite3_file *)pFile;
  Btree *pSrcBtree = NULL;
  sqlite3_file *src_file = NULL;
  unixFile *pSrcFile = NULL;
  char srcWalPath[MAXPATHLEN+5];
  int srcWalFD = -1;
  int rc = SQLITE_OK;
  void *pLock = NULL;
  int flags = 0;
  sqlite3 *srcdb2 = NULL;
  copyfile_state_t s;
  int corruptSrcFileLock = 0;
  int corruptDstFileLock = 0;
  int isSrcCorrupt = 0;
  int isDstCorrupt = 0;
  
  if( !sqlite3SafetyCheckOk(srcdb) ){
    return SQLITE_MISUSE;
  }
    
#if SQLITE_ENABLE_DATA_PROTECTION
  flags |= pFile->protFlags;
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
  if( isProxyLockingMode(pFile) ){
    flags |= SQLITE_OPEN_AUTOPROXY;
  }
#endif
  
  rc = sqlite3demo_superlock(pFile->zPath, 0, flags, 0, 0, &pLock);
  if( rc ){
    if( rc==SQLITE_CORRUPT || rc==SQLITE_NOTADB ){
      isDstCorrupt = 1;
      rc = sqlite3demo_superlock_corrupt(id, SQLITE_LOCK_EXCLUSIVE, &corruptDstFileLock);
    }
    if( rc ){
      return rc;
    }
  }
  /* get the src file descriptor adhering to the db struct access rules 
   ** this code is modeled after sqlite3_file_control() in main.c
   */ 
  sqlite3_mutex_enter(srcdb->mutex);
  if( srcdb->nDb>0 ){
    pSrcBtree = srcdb->aDb[0].pBt;
  }
  if( pSrcBtree ){
    Pager *pSrcPager;
    sqlite3BtreeEnter(pSrcBtree);
    pSrcPager = sqlite3BtreePager(pSrcBtree);
    assert( pSrcPager!=0 );
    src_file = sqlite3PagerFile(pSrcPager);
    assert( src_file!=0 );
    if( src_file->pMethods ){
      int srcFlags = 0;
      pSrcFile = (unixFile *)src_file;
      /* wal mode db cannot be opened readonly */
      if ((pSrcFile->openFlags & O_RDWR) == O_RDWR) {
        srcFlags = SQLITE_OPEN_READWRITE;
      } else {
        srcFlags = SQLITE_OPEN_READONLY;
      }
#if SQLITE_ENABLE_DATA_PROTECTION
      srcFlags |= pSrcFile->protFlags;
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
      if( isProxyLockingMode(pSrcFile) ){
        srcFlags |= SQLITE_OPEN_AUTOPROXY;
      }
#endif
      rc = sqlite3_open_v2(pSrcFile->zPath, &srcdb2, srcFlags, 0);
      if( rc==SQLITE_OK ){
        /* start a deferred transaction and read to establish a read lock */
        rc = sqlite3_exec(srcdb2, "BEGIN DEFERRED; PRAGMA schema_version", 0, 0, 0);
        if( rc==SQLITE_CORRUPT || rc==SQLITE_NOTADB ){
          isSrcCorrupt = 1;
          rc = sqlite3demo_superlock_corrupt(src_file, SQLITE_LOCK_SHARED, &corruptSrcFileLock);
        }
      }
    }
  }
  if( !srcdb2 || pSrcFile==NULL || pSrcFile->h<0){
    rc = SQLITE_INTERNAL;
  }
  if( rc!=SQLITE_OK ){
    goto end_replace_database;
  }
  /* both databases are locked appropriately, copy the src wal journal if 
   ** one exists and then the actual database file
   */
  strlcpy(srcWalPath, pSrcFile->zPath, MAXPATHLEN+5);
  strlcat(srcWalPath, "-wal", MAXPATHLEN+5);
  srcWalFD = open(srcWalPath, O_RDONLY);
  if( !(srcWalFD<0) ){
    char dstWalPath[MAXPATHLEN+5];
    int dstWalFD = -1;
    strlcpy(dstWalPath, pFile->zPath, MAXPATHLEN+5);
    strlcat(dstWalPath, "-wal", MAXPATHLEN+5);
    dstWalFD = open(dstWalPath, O_RDWR|O_CREAT, SQLITE_DEFAULT_FILE_PERMISSIONS);
    if( !(dstWalFD<0) ){
      s = copyfile_state_alloc();
      lseek(srcWalFD, 0, SEEK_SET);
      lseek(dstWalFD, 0, SEEK_SET);
      if( fcopyfile(srcWalFD, dstWalFD, s, COPYFILE_ALL) ){
        int err=errno;
        switch(err) {
          case ENOMEM:
            rc = SQLITE_NOMEM;
            break;
          default:
            pFile->lastErrno = err;
            rc = SQLITE_IOERR;
        }
      }
      copyfile_state_free(s);
      close(dstWalFD);
    }
    close(srcWalFD);
  }
  if( rc==SQLITE_OK ){
    /* before we copy, ensure that the file change counter will be modified */
    uint32_t srcChange = 0;
    uint32_t dstChange = 0;
    pread(pSrcFile->h, &srcChange, 4, 24);
    pread(pFile->h, &dstChange, 4, 24);
    
    /* copy the actual database */
    s = copyfile_state_alloc();
    lseek(pSrcFile->h, 0, SEEK_SET);
    lseek(pFile->h, 0, SEEK_SET);
    if( fcopyfile(pSrcFile->h, pFile->h, s, COPYFILE_ALL) ){
      int err=errno;
      switch(err) {
        case ENOMEM:
          rc = SQLITE_NOMEM;
          break;
        default:
          pFile->lastErrno = err;
          rc = SQLITE_IOERR;
      }
    }
    copyfile_state_free(s);
    
    if (srcChange == dstChange) {
      /* modify the change counter to force page zero to be reloaded */
      dstChange ++;
      pwrite(pFile->h, &dstChange, 4, 24);
    }
  }
  if( isSrcCorrupt ){
    sqlite3demo_superunlock_corrupt(src_file, corruptSrcFileLock);
  }else{
    /* done with the source db so end the transaction */
    sqlite3_exec(srcdb2, "COMMIT", 0, 0, 0);
  }
  /* zero out any old journal clutter */
  if( rc==SQLITE_OK ){
    int skipWAL = (srcWalFD<0)?0:1;
    unixInvalidateSupportFiles(pFile, skipWAL);
  }
  
end_replace_database:
  if( pSrcBtree ){
    sqlite3_close(srcdb2);
    sqlite3BtreeLeave(pSrcBtree);
  }
  sqlite3_mutex_leave(srcdb->mutex);
  if( isDstCorrupt ){
    sqlite3demo_superunlock_corrupt(id, corruptDstFileLock);
  }else{
    sqlite3demo_superunlock(pLock);
  }
  return rc;
}

#define SQLITE_FILE_HEADER_LEN 16
#include "btreeInt.h"
/* Check for a conflicting lock.  If one is found, print an this
 ** on standard output using the format string given and return 1.
 ** If there are no conflicting locks, return 0.
 */
static int unixIsLocked(
  pid_t pid,            /* PID to test for lock owner */
  int h,                /* File descriptor to check */
  int type,             /* F_RDLCK or F_WRLCK */
  unsigned int iOfst,   /* First byte of the lock */
  unsigned int iCnt,    /* Number of bytes in the lock range */
  const char *zType     /* Type of lock */
){
  struct flock lk;
  int err;
  
  memset(&lk, 0, sizeof(lk));
  lk.l_type = type;
  lk.l_whence = SEEK_SET;
  lk.l_start = iOfst;
  lk.l_len = iCnt;
  
  if( pid!=SQLITE_LOCKSTATE_ANYPID ){
#ifndef F_GETLKPID
# warning F_GETLKPID undefined, _sqlite3_lockstate falling back to F_GETLK
    err = fcntl(h, F_GETLK, &lk);
#else
    lk.l_pid = pid;
    err = fcntl(h, F_GETLKPID, &lk);
#endif
  }else{
    err = fcntl(h, F_GETLK, &lk);
  }
  
  if( err==(-1) ){
    fprintf(stderr, "fcntl(%d) failed: errno=%d\n", h, errno);
    return -1;
  }
  
  if( lk.l_type!=F_UNLCK && (pid==SQLITE_LOCKSTATE_ANYPID || lk.l_pid==pid) ){
#ifdef SQLITE_DEBUG
    fprintf(stderr, "%s lock held by %d\n", zType, (int)lk.l_pid);
#endif
    return 1;
  } 
  return 0;
}

static int unixLockstatePid(unixFile *, pid_t, int *);

#endif /* (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__) */
                               
/*
** Information and control of an open file handle.
*/
static int unixFileControl(sqlite3_file *id, int op, void *pArg){
  unixFile *pFile = (unixFile*)id;
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = pFile->eFileLock;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_LAST_ERRNO: {
      *(int*)pArg = pFile->lastErrno;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_CHUNK_SIZE: {
      pFile->szChunk = *(int *)pArg;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_SIZE_HINT: {
      return fcntlSizeHint(pFile, *(i64 *)pArg);
    }
    case SQLITE_FCNTL_PERSIST_WAL: {
      int bPersist = *(int*)pArg;
      if( bPersist<0 ){
        *(int*)pArg = (pFile->ctrlFlags & UNIXFILE_PERSIST_WAL)!=0;
      }else if( bPersist==0 ){
        pFile->ctrlFlags &= ~UNIXFILE_PERSIST_WAL;
      }else{
        pFile->ctrlFlags |= UNIXFILE_PERSIST_WAL;
      }
      return SQLITE_OK;
    }
#ifndef NDEBUG
    /* The pager calls this method to signal that it has done
    ** a rollback and that the database is therefore unchanged and
    ** it hence it is OK for the transaction change counter to be
    ** unchanged.
    */
    case SQLITE_FCNTL_DB_UNCHANGED: {
      ((unixFile*)id)->dbUpdate = 0;
      return SQLITE_OK;
    }
#endif
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
    case SQLITE_FCNTL_SET_LOCKPROXYFILE:
    case SQLITE_FCNTL_GET_LOCKPROXYFILE: {
      return proxyFileControl(id,op,pArg);
    }
#endif /* SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) */
#if (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__)
    case SQLITE_FCNTL_TRUNCATE_DATABASE: {






      return unixTruncateDatabase(pFile, (pArg ? (*(int *)pArg) : 0));






    }

    case SQLITE_FCNTL_REPLACE_DATABASE: {







      return unixReplaceDatabase(pFile, (sqlite3 *)pArg);
    }


    case SQLITE_FCNTL_LOCKSTATE_PID: {































      LockstatePID *pLockstate;








      int rc;








      
      if( pArg==NULL ){
        return SQLITE_MISUSE;
      }
      pLockstate = (LockstatePID *)pArg;








      rc = unixLockstatePid(pFile, pLockstate->pid, &(pLockstate->state));



































































































































































      return rc;
    }
#endif /* (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__) */
    case SQLITE_FCNTL_SYNC_OMITTED: {
      return SQLITE_OK;  /* A no-op */
    }
  }

    pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
    if( pShmNode->mutex==0 ){
      rc = SQLITE_NOMEM;
      goto shm_open_err;
    }

    if( pInode->bProcessLock==0 ){
      const char *zRO;
      zRO = sqlite3_uri_parameter(pDbFd->zPath, "readonly_shm");
      if( zRO && sqlite3GetBoolean(zRO) ){
        pShmNode->h = robust_open(zShmFilename, O_RDONLY,
                                  (sStat.st_mode & 0777));
        pShmNode->isReadonly = 1;
      }else{
        pShmNode->h = robust_open(zShmFilename, O_RDWR|O_CREAT,
                               (sStat.st_mode & 0777));
      }
      if( pShmNode->h<0 ){
        const char *zRO;
        zRO = sqlite3_uri_parameter(pDbFd->zPath, "readonly_shm");
        if( zRO && sqlite3GetBoolean(zRO) ){
          pShmNode->h = robust_open(zShmFilename, O_RDONLY,
                                    (sStat.st_mode & 0777));
          pShmNode->isReadonly = 1;

#else
# define unixShmMap     0
# define unixShmLock    0
# define unixShmBarrier 0
# define unixShmUnmap   0
#endif /* #ifndef SQLITE_OMIT_WAL */

#if (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__)
static const char *unixTempFileDir(void);

static int unixInvalidateSupportFiles(unixFile *pFile, int skipWAL) {
  char jPath[MAXPATHLEN+9];
  int zLen = strlcpy(jPath, pFile->zPath, MAXPATHLEN+9);
  if( zLen<MAXPATHLEN ){
    size_t jLen;
    const char extensions[3][9] = { "-wal", "-journal", "-shm" };
    int j = (skipWAL ? 1 : 0);
    for( ; j<3; j++ ){
      
      /* Check to see if the shm file is already opened for this pFile */
      if( j==2 ){
        unixEnterMutex(); /* Because pFile->pInode is shared across threads */
        unixShmNode *pShmNode = pFile->pInode->pShmNode;
        if( pShmNode && !pShmNode->isReadonly ){
          struct stat sStat;
          sqlite3_mutex_enter(pShmNode->mutex);
          
          if( pShmNode->h>=0 && !osFstat(pShmNode->h, &sStat) ){
            unsigned long size = (sStat.st_size<4) ? sStat.st_size : 4;
            if( size>0 ){
              bzero(pShmNode->apRegion[0], size);
              sqlite3_mutex_leave(pShmNode->mutex);
              unixLeaveMutex();
              continue;
            }
          }
          sqlite3_mutex_leave(pShmNode->mutex);
        }
        unixLeaveMutex();
      }
      jLen = strlcpy(&jPath[zLen], extensions[j], 9);
      if( jLen < 9 ){
        int jflags = (j<2) ? O_TRUNC : O_RDWR;
        int jfd = open(jPath, jflags);
        if( jfd==(-1) ){
          if( errno!=ENOENT ){
            perror(jPath);
          }
        } else {
          if( j==2 ){
            struct stat sStat;
            if( !osFstat(jfd, &sStat) ){
              unsigned long size = (sStat.st_size<4) ? sStat.st_size : 4;
              if( size>0 ){
                uint32_t zero = 0;
                pwrite(jfd, &zero, (size_t)size, 0);
              }
            }
          }
          fsync(jfd);
          close(jfd);
        }
      }
    }
  }
  return SQLITE_OK;
}

static int unixTruncateDatabase(unixFile *pFile, int bFlags) {
  sqlite3_file *id = (sqlite3_file *)pFile;
  int rc = SQLITE_OK;
  void *pLock = NULL;
  int flags = 0;
  int corruptFileLock = 0;
  int isCorrupt = 0;
    
#if SQLITE_ENABLE_DATA_PROTECTION
  flags |= pFile->protFlags;
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
  if( isProxyLockingMode(pFile) ){
    flags |= SQLITE_OPEN_AUTOPROXY;
  }
#endif
  
  rc = sqlite3demo_superlock(pFile->zPath, 0, flags, 0, 0, &pLock);
  if( rc ){
    if( rc==SQLITE_CORRUPT || rc==SQLITE_NOTADB ){
      isCorrupt = 1;
      rc = sqlite3demo_superlock_corrupt(id, SQLITE_LOCK_EXCLUSIVE, &corruptFileLock);
    }
    if( rc ){
      return rc;
    }
  }
  rc = pFile->pMethod->xTruncate(id, ((pFile->fsFlags & SQLITE_FSFLAGS_IS_MSDOS) != 0) ? 1L : 0L);
  if( rc==SQLITE_OK ){
    unixInvalidateSupportFiles(pFile, 0);
  }
  pFile->pMethod->xSync(id, SQLITE_SYNC_FULL);


  if( isCorrupt ){
    sqlite3demo_superunlock_corrupt(id, corruptFileLock);
  }else{
    sqlite3demo_superunlock(pLock);
  }
  return rc;
}

/*
 ** Lock locations for shared-memory locks used by WAL mode.
 */
#ifndef SHM_BASE
# define SHM_BASE          120
# define SHM_WRITE         SHM_BASE
# define SHM_CHECKPOINT    (SHM_BASE+1)
# define SHM_RECOVER       (SHM_BASE+2)
# define SHM_READ_FIRST    (SHM_BASE+3)
# define SHM_READ_SIZE     5
#endif /* SHM_BASE */

/*
** This test only works for lock testing on unix/posix VFS.
** Adapted from tool/getlock.c f4c39b651370156cae979501a7b156bdba50e7ce
*/
static int unixLockstatePid(unixFile *pFile, pid_t pid, int *pLockstate){
  int hDb;        /* File descriptor for the open database file */
  int hShm = -1;  /* File descriptor for WAL shared-memory file */
  ssize_t got;    /* Bytes read from header */
  int isWal;                 /* True if in WAL mode */
  int nLock = 0;             /* Number of locks held */
  unsigned char aHdr[100];   /* Database header */
  
  assert(pLockstate);
  
  /* make sure we are dealing with a database file */
  hDb = pFile->h;
  if( hDb<0 ){
    *pLockstate = SQLITE_LOCKSTATE_ERROR;
    return SQLITE_ERROR;
  }
  assert( (strlen(SQLITE_FILE_HEADER)+1)==SQLITE_FILE_HEADER_LEN );
  got = pread(hDb, aHdr, 100, 0);
  if( got<0 ){
    *pLockstate = SQLITE_LOCKSTATE_ERROR;
    return SQLITE_ERROR;
  }
  if( got!=100 || memcmp(aHdr, SQLITE_FILE_HEADER, SQLITE_FILE_HEADER_LEN)!=0 ){
    *pLockstate = SQLITE_LOCKSTATE_NOTADB;
    return SQLITE_NOTADB;
  }
  
  /* First check for an exclusive lock */
  nLock += unixIsLocked(pid, hDb, F_RDLCK, SHARED_FIRST, SHARED_SIZE, "EXCLUSIVE");
  isWal = aHdr[18]==2;
  if( nLock==0 && isWal==0 ){
    /* Rollback mode */
    nLock += unixIsLocked(pid, hDb, F_WRLCK, PENDING_BYTE, SHARED_SIZE+2, "PENDING|RESERVED|SHARED");
  }
  if( nLock==0 && isWal!=0 ){
    /* lookup the file descriptor for the shared memory file if we have it open in this process */
    unixEnterMutex(); /* Because pFile->pInode is shared across threads */
    unixShmNode *pShmNode = pFile->pInode->pShmNode;
    if( pShmNode ){
      sqlite3_mutex_enter(pShmNode->mutex);
      
      hShm = pShmNode->h;
      if( hShm >= 0){
        if( unixIsLocked(pid, hShm, F_RDLCK, SHM_RECOVER, 1, "WAL-RECOVERY") ||
           unixIsLocked(pid, hShm, F_RDLCK, SHM_WRITE, 1, "WAL-WRITE") ){
          nLock = 1;
        }
      }
      
      sqlite3_mutex_leave(pShmNode->mutex);
    } 
    
    if( hShm<0 ){
      /* the shared memory file isn't open in this process space, open our own FD */
      char zShm[MAXPATHLEN];
      
      /* WAL mode */
      strlcpy(zShm, pFile->zPath, MAXPATHLEN);
      strlcat(zShm, "-shm", MAXPATHLEN);
      hShm = open(zShm, O_RDONLY, 0);
      if( hShm<0 ){
        *pLockstate = SQLITE_LOCKSTATE_OFF;
        unixLeaveMutex();
        return SQLITE_OK;
      }
      if( unixIsLocked(pid, hShm, F_RDLCK, SHM_RECOVER, 1, "WAL-RECOVERY") ||
         unixIsLocked(pid, hShm, F_RDLCK, SHM_WRITE, 1, "WAL-WRITE") ){
        nLock = 1;
      }
      close(hShm);
    }
    unixLeaveMutex();
  }
  if( nLock>0 ){
    *pLockstate = SQLITE_LOCKSTATE_ON;
  } else {
    *pLockstate = SQLITE_LOCKSTATE_OFF;
  }
  return SQLITE_OK;
}

#endif /* (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__) */



/*
** Here ends the implementation of all sqlite3_file methods.
**
********************** End sqlite3_file Methods *******************************
******************************************************************************/

** portability layer.
*/
typedef struct winFile winFile;
struct winFile {
  const sqlite3_io_methods *pMethod; /*** Must be first ***/
  sqlite3_vfs *pVfs;      /* The VFS used to open this file */
  HANDLE h;               /* Handle for accessing the file */
  u8 locktype;            /* Type of lock currently held on this file */
  short sharedLockByte;   /* Randomly chosen byte used as a shared lock */
  u8 bPersistWal;         /* True to persist WAL files */
  DWORD lastErrno;        /* The Windows errno from the last I/O error */
  DWORD sectorSize;       /* Sector size of the device file is on */
  winShm *pShm;           /* Instance of shared memory on this file */
  const char *zPath;      /* Full pathname of this file */
  int szChunk;            /* Chunk size configured by FCNTL_CHUNK_SIZE */
#if SQLITE_OS_WINCE
  WCHAR *zDeleteOnClose;  /* Name of file to delete when closing */

  return rc;
}

/*
** Control and query of the open file handle.
*/
static int winFileControl(sqlite3_file *id, int op, void *pArg){
  winFile *pFile = (winFile*)id;
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = pFile->locktype;
      return SQLITE_OK;
    }
    case SQLITE_LAST_ERRNO: {
      *(int*)pArg = (int)pFile->lastErrno;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_CHUNK_SIZE: {
      pFile->szChunk = *(int *)pArg;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_SIZE_HINT: {
      sqlite3_int64 sz = *(sqlite3_int64*)pArg;
      SimulateIOErrorBenign(1);
      winTruncate(id, sz);
      SimulateIOErrorBenign(0);
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_PERSIST_WAL: {
      int bPersist = *(int*)pArg;
      if( bPersist<0 ){
        *(int*)pArg = pFile->bPersistWal;
      }else{
        pFile->bPersistWal = bPersist!=0;
      }
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_SYNC_OMITTED: {
      return SQLITE_OK;
    }
  }
  return SQLITE_NOTFOUND;
}

  /* Open the connection to the log file. If this operation fails, 
  ** (e.g. due to malloc() failure), return an error code.
  */
  if( rc==SQLITE_OK ){
#if SQLITE_ENABLE_DATA_PROTECTION
    rc = sqlite3WalOpen(pPager->pVfs, pPager->fd, pPager->zWal, pPager->exclusiveMode,
        pPager->journalSizeLimit, (pPager->vfsFlags & (SQLITE_OPEN_FILEPROTECTION_MASK | SQLITE_OPEN_READONLY)), 
        &pPager->pWal);
#else
    rc = sqlite3WalOpen(pPager->pVfs, pPager->fd, pPager->zWal, pPager->exclusiveMode,
        pPager->journalSizeLimit, (pPager->vfsFlags & SQLITE_OPEN_READONLY), &pPager->pWal);
#endif
  }

  return rc;
}

** when the database connection has [PRAGMA synchronous] set to OFF.)^
** Some specialized VFSes need this signal in order to operate correctly
** when [PRAGMA synchronous | PRAGMA synchronous=OFF] is set, but most 
** VFSes do not need this signal and should silently ignore this opcode.
** Applications should not call [sqlite3_file_control()] with this
** opcode as doing so may disrupt the operation of the specialized VFSes
** that do require it.  
**
** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
** persistent [WAL | Write AHead Log] setting.  By default, the auxiliary
** write ahead log and shared memory files used for transaction control
** are automatically deleted when the latest connection to the database
** closes.  Setting persistent WAL mode causes those files to persist after
** close.  Persisting the files is useful when other processes that do not
** have write permission on the directory containing the database file want
** to read the database file, as the WAL and shared memory files must exist
** in order for the database to be readable.  The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
** WAL mode.  If the integer is -1, then it is overwritten with the current
** WAL persistence setting.
**
*/
#define SQLITE_FCNTL_LOCKSTATE          1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE  2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE  3
#define SQLITE_FCNTL_LAST_ERRNO         4
#define SQLITE_FCNTL_SIZE_HINT          5
#define SQLITE_FCNTL_CHUNK_SIZE         6
#define SQLITE_FCNTL_FILE_POINTER       7
#define SQLITE_FCNTL_SYNC_OMITTED       8
#define SQLITE_FCNTL_PERSIST_WAL       10
/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO

/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only

**
** ^The sqlite3_data_count(P) interface returns the number of columns in the
** current row of the result set of [prepared statement] P.
** ^If prepared statement P does not have results ready to return
** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
** interfaces) then sqlite3_data_count(P) returns 0.
** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
** will return non-zero if previous call to [sqlite3_step](P) returned
** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
** where it always returns zero since each step of that multi-step
** pragma returns 0 columns of data.
**
** See also: [sqlite3_column_count()]
*/
int sqlite3_data_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Fundamental Datatypes

**
** There is no support for identifying db files encrypted via SEE encryption
** currently.  Zero byte files are tested for sqlite locks, but if no sqlite 
** locks are present then SQLITE_LOCKSTATE_NOTADB is returned.
*/
extern int _sqlite3_lockstate(const char *path, pid_t pid);

/*
** Test an open database connection for sqlite locks held by a process ID,
** if a process has an open database connection this will avoid trashing file
** locks by re-using open file descriptors for the database file and support
** files (-shm)
*/
#define SQLITE_FCNTL_LOCKSTATE_PID          103

/*
** Pass the SQLITE_TRUNCATE_DATABASE operation code to sqlite3_file_control() 
** to truncate a database and its associated journal file to zero length.
*/
#define SQLITE_FCNTL_TRUNCATE_DATABASE      101
#define SQLITE_TRUNCATE_DATABASE            SQLITE_FCNTL_TRUNCATE_DATABASE

/*
** Pass the SQLITE_REPLACE_DATABASE operation code to sqlite3_file_control() 
** and a sqlite3 pointer to another open database file to safely copy the 
** contents of that database file into the receiving database.
*/
#define SQLITE_FCNTL_REPLACE_DATABASE       102
#define SQLITE_REPLACE_DATABASE             SQLITE_FCNTL_REPLACE_DATABASE

#endif

#endif
#define MEMTYPE_HEAP       0x01  /* General heap allocations */
#define MEMTYPE_LOOKASIDE  0x02  /* Might have been lookaside memory */
#define MEMTYPE_SCRATCH    0x04  /* Scratch allocations */
#define MEMTYPE_PCACHE     0x08  /* Page cache allocations */
#define MEMTYPE_DB         0x10  /* Uses sqlite3DbMalloc, not sqlite_malloc */


#if (SQLITE_ENABLE_APPLE_SPI>0) && defined(__APPLE__)

/*
** An instance of the following structure is used to hold the process ID
** and return-by-reference lockstate value.  The SQLITE_FCNTL_LOCKSTATE_PID
** requires the 4th argument to sqlite3_file_control to be a pointer to an
** instance of LockstatePID initialized with a LockstatePID.pid value equal
** to a process ID to be tested, or the special value SQLITE_LOCKSTATE_ANYPID
** The Lockstate.state value is always set to one of the following values
** when sqlite3_file_control returns:
** 
**   SQLITE_LOCKSTATE_OFF    no active sqlite file locks match the specified pid
**   SQLITE_LOCKSTATE_ON     active sqlite file locks match the specified pid
**   SQLITE_LOCKSTATE_NOTADB path points to a file that is not an sqlite db file
**   SQLITE_LOCKSTATE_ERROR  path was not vaild or was unreadable
*/
typedef struct LockstatePID LockstatePID;
struct LockstatePID {
  pid_t pid;                 /* Process ID to test */
  int state;                 /* The state of the lock (return value) */
};

#endif

#endif /* _SQLITEINT_H_ */

static int file_control_truncate_test(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  sqlite3 *db;
  int flags;
  int rc;
  
  if( objc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"",
                     Tcl_GetStringFromObj(objv[0], 0), " DB FLAGS", 0);
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ){
    return TCL_ERROR;
  }
  if( Tcl_GetIntFromObj(interp, objv[2], &flags) ){
    return TCL_ERROR;
  }
  rc = sqlite3_file_control(db, NULL, SQLITE_TRUNCATE_DATABASE, &flags);
  if( rc ){ 
    Tcl_SetObjResult(interp, Tcl_NewIntObj(rc)); 
    return TCL_ERROR; 
  }
  return TCL_OK;  
}

 */
static int path_is_local(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){

  const char *zPath;
  int nPath;
  
  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"",
                     Tcl_GetStringFromObj(objv[0], 0), " PATH", 0);
    return TCL_ERROR;

 */
static int path_is_dos(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){

  const char *zPath;
  int nPath;
  
  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"",
                     Tcl_GetStringFromObj(objv[0], 0), " PATH", 0);
    return TCL_ERROR;

  }
#else
  Tcl_SetObjResult(interp, Tcl_NewIntObj(0)); 
#endif
  
  return TCL_OK;  
}

/*
** tclcmd:   file_control_persist_wal DB PERSIST-FLAG
**
** This TCL command runs the sqlite3_file_control interface with
** the SQLITE_FCNTL_PERSIST_WAL opcode.
*/
static int file_control_persist_wal(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  sqlite3 *db;
  int rc;
  int bPersist;
  char z[100];
  
  if( objc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"",
                     Tcl_GetStringFromObj(objv[0], 0), " DB FLAG", 0);
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ){
    return TCL_ERROR;
  }
  if( Tcl_GetIntFromObj(interp, objv[2], &bPersist) ) return TCL_ERROR;
  rc = sqlite3_file_control(db, NULL, SQLITE_FCNTL_PERSIST_WAL, (void*)&bPersist);
  sqlite3_snprintf(sizeof(z), z, "%d %d", rc, bPersist);
  Tcl_AppendResult(interp, z, (char*)0);
  return TCL_OK;  
}


/*
** tclcmd:   sqlite3_vfs_list
**
**   Return a tcl list containing the names of all registered vfs's.
*/
static int vfs_list(

     { "file_control_lockproxy_test", file_control_lockproxy_test,  0   },
#ifdef __APPLE__
     { "file_control_truncate_test", file_control_truncate_test,  0   },
     { "file_control_replace_test", file_control_replace_test,  0   },
#endif 
     { "file_control_chunksize_test", file_control_chunksize_test,  0   },
     { "file_control_sizehint_test", file_control_sizehint_test,  0   },
     { "file_control_persist_wal",    file_control_persist_wal,     0   },
     { "sqlite3_vfs_list",           vfs_list,     0   },
     { "sqlite3_create_function_v2", test_create_function_v2, 0 },
     { "path_is_local",              path_is_local,  0   },
     { "path_is_dos",                path_is_dos,  0   },

     /* Functions from os.h */
#ifndef SQLITE_OMIT_UTF16

  int nRow;                            /* Stop when row count reaches this */
  int nSub = 0;                        /* Number of sub-vdbes seen so far */
  SubProgram **apSub = 0;              /* Array of sub-vdbes */
  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
  sqlite3 *db = p->db;                 /* The database connection */
  int i;                               /* Loop counter */
  int rc = SQLITE_OK;                  /* Return code */
  Mem *pMem = &p->aMem[1];             /* First Mem of result set */

  assert( p->explain );
  assert( p->magic==VDBE_MAGIC_RUN );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );

  /* Even though this opcode does not use dynamic strings for
  ** the result, result columns may become dynamic if the user calls
  ** sqlite3_column_text16(), causing a translation to UTF-16 encoding.
  */
  releaseMemArray(pMem, 8);
  p->pResultSet = 0;

  if( p->rc==SQLITE_NOMEM ){
    /* This happens if a malloc() inside a call to sqlite3_column_text() or
    ** sqlite3_column_text16() failed.  */
    db->mallocFailed = 1;
    return SQLITE_ERROR;
  }

      {
        pMem->flags = MEM_Null;                       /* Comment */
        pMem->type = SQLITE_NULL;
      }
    }

    p->nResColumn = 8 - 4*(p->explain-1);
    p->pResultSet = &p->aMem[1];
    p->rc = SQLITE_OK;
    rc = SQLITE_ROW;
  }
  return rc;
}
#endif /* SQLITE_OMIT_EXPLAIN */

  if( pParse->explain && nMem<10 ){
    nMem = 10;
  }
  memset(zCsr, 0, zEnd-zCsr);
  zCsr += (zCsr - (u8*)0)&7;
  assert( EIGHT_BYTE_ALIGNMENT(zCsr) );

  p->expired = 0;
  
  /* Memory for registers, parameters, cursor, etc, is allocated in two
  ** passes.  On the first pass, we try to reuse unused space at the 
  ** end of the opcode array.  If we are unable to satisfy all memory
  ** requirements by reusing the opcode array tail, then the second
  ** pass will fill in the rest using a fresh allocation.  
  **
  ** This two-pass approach that reuses as much memory as possible from

  pRet->pDbFd = pDbFd;
  pRet->readLock = -1;
  pRet->mxWalSize = mxWalSize;
  pRet->zWalName = zWalName;
  pRet->exclusiveMode = (bNoShm ? WAL_HEAPMEMORY_MODE: WAL_NORMAL_MODE);

  /* Open file handle on the write-ahead log file. */
  if( flags&SQLITE_OPEN_READONLY ){
    vfsFlags = flags | SQLITE_OPEN_WAL;
  } else {
    vfsFlags = flags | (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_WAL);
  }
  rc = sqlite3OsOpen(pVfs, zWalName, pRet->pWalFd, vfsFlags, &vfsFlags);
  if( rc==SQLITE_OK && vfsFlags&SQLITE_OPEN_READONLY ){
    pRet->readOnly = WAL_RDONLY;
  }

  if( rc!=SQLITE_OK ){
    walIndexClose(pRet, 0);

    ** the database. In this case checkpoint the database and unlink both
    ** the wal and wal-index files.
    **
    ** The EXCLUSIVE lock is not released before returning.
    */
    rc = sqlite3OsLock(pWal->pDbFd, SQLITE_LOCK_EXCLUSIVE);
    if( rc==SQLITE_OK ){
      int bPersistWal = -1;
      if( pWal->exclusiveMode==WAL_NORMAL_MODE ){
        pWal->exclusiveMode = WAL_EXCLUSIVE_MODE;
      }
      rc = sqlite3WalCheckpoint(
          pWal, SQLITE_CHECKPOINT_PASSIVE, 0, 0, sync_flags, nBuf, zBuf, 0, 0
      );
      sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_PERSIST_WAL, &bPersistWal);
      if( rc==SQLITE_OK && bPersistWal!=1 ){
        isDelete = 1;
      }
    }

    walIndexClose(pWal, isDelete);
    sqlite3OsClose(pWal->pWalFd);
    if( isDelete ){

  **
  ** There are two copies of the header at the beginning of the wal-index.
  ** When reading, read [0] first then [1].  Writes are in the reverse order.
  ** Memory barriers are used to prevent the compiler or the hardware from
  ** reordering the reads and writes.
  */
  aHdr = walIndexHdr(pWal);
  if( aHdr==NULL ){
    return 1; /* Shouldn't be getting NULL from walIndexHdr, but we are */
  }
  memcpy(&h1, (void *)&aHdr[0], sizeof(h1));
  walShmBarrier(pWal);
  memcpy(&h2, (void *)&aHdr[1], sizeof(h2));

  if( memcmp(&h1, &h2, sizeof(h1))!=0 ){
    return 1;   /* Dirty read */
  }  

  ** is more of a scheduler yield than an actual delay.  But on the 10th
  ** an subsequent retries, the delays start becoming longer and longer, 
  ** so that on the 100th (and last) RETRY we delay for 21 milliseconds.
  ** The total delay time before giving up is less than 1 second.
  */
  if( cnt>5 ){
    int nDelay = 1;                      /* Pause time in microseconds */
    if( cnt>500 ){
      VVA_ONLY( pWal->lockError = 1; )
      return SQLITE_PROTOCOL;
    }
    if( cnt>=10 ) nDelay = (cnt-9)*238;  /* Max delay 21ms. Total delay 996ms */
    sqlite3OsSleep(pWal->pVfs, nDelay);
  }

# 2011 July 26
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# This file contains tests for using WAL with persistent WAL file mode.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
set ::testprefix walpersist

do_test walpersist-1.0 {
  db eval {
    PRAGMA journal_mode=WAL;
    CREATE TABLE t1(a);
    INSERT INTO t1 VALUES(randomblob(5000));
  }
  file exists test.db-wal
} {1}
do_test walpersist-1.1 {
  file exists test.db-shm
} {1}
do_test walpersist-1.2 {
  db close
  list [file exists test.db] [file exists test.db-wal] [file exists test.db-shm]
} {1 0 0}
do_test walpersist-1.3 {
  sqlite3 db test.db
  db eval {SELECT length(a) FROM t1}
} {5000}
do_test walpersist-1.4 {
  list [file exists test.db] [file exists test.db-wal] [file exists test.db-shm]
} {1 1 1}
do_test walpersist-1.5 {
  file_control_persist_wal db -1
} {0 0}
do_test walpersist-1.6 {
  file_control_persist_wal db 1
} {0 1}
do_test walpersist-1.7 {
  file_control_persist_wal db -1
} {0 1}
do_test walpersist-1.8 {
  file_control_persist_wal db 0
} {0 0}
do_test walpersist-1.9 {
  file_control_persist_wal db -1
} {0 0}
do_test walpersist-1.10 {
  file_control_persist_wal db 1
} {0 1}
do_test walpersist-1.11 {
  db close
  list [file exists test.db] [file exists test.db-wal] [file exists test.db-shm]
} {1 1 1}

  


finish_test