set rc
}

# Same as [step_ota], except using a URI to open the target db.
#
proc step_ota_uri {target ota} {
  while 1 {
    sqlite3ota ota file:$target?xyz=123 $ota
    set rc [ota step]
    ota close
    if {$rc != "SQLITE_OK"} break
  }
  set rc
}

  set rc
}

# Same as [step_ota], except using a URI to open the target db.
#
proc step_ota_uri {target ota} {
  while 1 {
    sqlite3ota ota file:$target?xyz=&abc=123 $ota
    set rc [ota step]
    ota close
    if {$rc != "SQLITE_OK"} break
  }
  set rc
}

#define OTA_CREATE_STATE "CREATE TABLE IF NOT EXISTS ota.ota_state"        \
                             "(k INTEGER PRIMARY KEY, v)"

typedef struct OtaState OtaState;
typedef struct OtaObjIter OtaObjIter;



/*
** A structure to store values read from the ota_state table in memory.
*/
struct OtaState {
  int eStage;
  char *zTbl;
................................................................................
*/
#define OTA_PK_NOTABLE        0
#define OTA_PK_NONE           1
#define OTA_PK_IPK            2
#define OTA_PK_EXTERNAL       3
#define OTA_PK_WITHOUT_ROWID  4
#define OTA_PK_VTAB           5


/*
** OTA handle.
*/
struct sqlite3ota {
  int eStage;                     /* Value of OTA_STATE_STAGE field */
  sqlite3 *db;                    /* "main" -> target db, "ota" -> ota db */
................................................................................
  char *zOta;                     /* Path to ota db */
  int rc;                         /* Value returned by last ota_step() call */
  char *zErrmsg;                  /* Error message if rc!=SQLITE_OK */
  int nStep;                      /* Rows processed for current object */
  int nProgress;                  /* Rows processed for all objects */
  OtaObjIter objiter;             /* Iterator for skipping through tbl/idx */
  sqlite3_ckpt *pCkpt;            /* Incr-checkpoint handle */
  sqlite3_vfs *pVfs;              /* Special ota VFS object */

  unsigned int iCookie;
};





















static void otaCreateVfs(sqlite3ota*, const char*);
static void otaDeleteVfs(sqlite3ota*);

/*
** Prepare the SQL statement in buffer zSql against database handle db.
** If successful, set *ppStmt to point to the new statement and return
................................................................................
      p->rc = sqlite3_exec(p->db, zSql, 0, 0, &p->zErrmsg);
      sqlite3_free(zSql);
    }
  }
  va_end(ap);
  return p->rc;
}















/*
** Allocate and zero the pIter->azTblCol[] and abTblPk[] arrays so that
** there is room for at least nCol elements. If an OOM occurs, store an
** error code in the OTA handle passed as the first argument.
*/
static void otaAllocateIterArrays(sqlite3ota *p, OtaObjIter *pIter, int nCol){
  int nByte = (2*sizeof(char*) + sizeof(int) + 2*sizeof(unsigned char)) * nCol;
  char **azNew;

  assert( p->rc==SQLITE_OK );
  azNew = (char**)sqlite3_malloc(nByte);
  if( azNew ){
    memset(azNew, 0, nByte);
    pIter->azTblCol = azNew;
    pIter->azTblType = &azNew[nCol];
    pIter->aiSrcOrder = (int*)&pIter->azTblType[nCol];
    pIter->abTblPk = (unsigned char*)&pIter->aiSrcOrder[nCol];
    pIter->abNotNull = (unsigned char*)&pIter->abTblPk[nCol];
  }else{
    p->rc = SQLITE_NOMEM;
  }
}

static char *otaStrndup(const char *zStr, int nStr, int *pRc){
  char *zRet = 0;
  assert( *pRc==SQLITE_OK );

................................................................................
    sqlite3_free(zSql);
    zSql = 0;
  }
  va_end(ap);
  return zSql;
}

static void *otaMalloc(sqlite3ota *p, int nByte){
  void *pRet = 0;
  if( p->rc==SQLITE_OK ){
    pRet = sqlite3_malloc(nByte);
    if( pRet==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
      memset(pRet, 0, nByte);
    }
  }
  return pRet;
}

/*
** This function constructs and returns a pointer to a nul-terminated 
** string containing some SQL clause or list based on one or more of the 
** column names currently stored in the pIter->azTblCol[] array.
*/
static char *otaObjIterGetCollist(
  sqlite3ota *p,                  /* OTA object */
................................................................................
    }
  }
  return zList;
}

static char *otaObjIterGetBindlist(sqlite3ota *p, int nBind){
  char *zRet = 0;
  if( p->rc==SQLITE_OK ){
    int nByte = nBind*2 + 1;

    zRet = sqlite3_malloc(nByte);
    if( zRet==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
      int i;
      for(i=0; i<nBind; i++){
        zRet[i*2] = '?';
        zRet[i*2+1] = (i+1==nBind) ? '\0' : ',';
      }
    }
  }
  return zRet;
}

/*
** The iterator currently points to a table (not index) of type 
................................................................................
** error occurs, leave an error code and message in the OTA handle.
*/
static void otaOpenDatabase(sqlite3ota *p){
  int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE;
  assert( p->rc==SQLITE_OK );
  assert( p->db==0 );

  p->rc = sqlite3_open_v2(p->zTarget, &p->db, flags, p->pVfs->zName);
  if( p->rc ){
    p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(p->db));
  }








  otaMPrintfExec(p, "ATTACH %Q AS ota", p->zOta);


}

/*
** This routine is a copy of the sqlite3FileSuffix3() routine from the core.
** It is a no-op unless SQLITE_ENABLE_8_3_NAMES is defined.
**
** If SQLITE_ENABLE_8_3_NAMES is set at compile-time and if the database
................................................................................
        p->nProgress = pState->nProgress;
      }
    }
    assert( p->rc!=SQLITE_OK || p->eStage!=0 );

    if( p->rc==SQLITE_OK ){
      if( p->eStage==OTA_STAGE_OAL ){
        const char *zScript =
          "PRAGMA journal_mode=off;"
          "BEGIN IMMEDIATE;"
        ;



        p->rc = sqlite3_exec(p->db, zScript, 0, 0, &p->zErrmsg);


  
        /* Point the object iterator at the first object */
        if( p->rc==SQLITE_OK ){
          p->rc = otaObjIterFirst(p, &p->objiter);
        }
  
        if( p->rc==SQLITE_OK ){
................................................................................
**           non-zero (to tell SQLite that it does exist) anyway.
**
**   5. In OTA_STAGE_OAL mode, if SQLite tries to open a *-wal file 
**      associated with a target database, open the corresponding *-oal file
**      instead.
*/

typedef struct ota_file ota_file;
typedef struct ota_vfs ota_vfs;

struct ota_file {
  sqlite3_file base;              /* sqlite3_file methods */
  sqlite3_file *pReal;            /* Underlying file handle */
  ota_vfs *pOtaVfs;               /* Pointer to the ota_vfs object */

  int nShm;                       /* Number of entries in apShm[] array */
  char **apShm;                   /* Array of mmap'd *-shm regions */
  char *zFilename;                /* Filename for *-oal file only */
};

struct ota_vfs {
  sqlite3_vfs base;             /* ota VFS shim methods */
  sqlite3_vfs *pRealVfs;        /* Underlying VFS */
  sqlite3ota *pOta;
  ota_file *pTargetDb;          /* Target database file descriptor */
  const char *zTargetDb;        /* Path that pTargetDb was opened with */
};

/*
** Close an ota file.
*/
static int otaVfsClose(sqlite3_file *pFile){
  ota_file *p = (ota_file*)pFile;
  ota_vfs *pOtaVfs = p->pOtaVfs;
  int rc;
  int i;

  /* Free the contents of the apShm[] array. And the array itself. */
  for(i=0; i<p->nShm; i++){
    sqlite3_free(p->apShm[i]);
  }
  sqlite3_free(p->apShm);
  p->apShm = 0;
  sqlite3_free(p->zFilename);

  if( p==pOtaVfs->pTargetDb ){
    pOtaVfs->pTargetDb = 0;
    pOtaVfs->zTargetDb = 0;
  }

  rc = p->pReal->pMethods->xClose(p->pReal);
  return rc;
}


/*
................................................................................
static int otaVfsRead(
  sqlite3_file *pFile, 
  void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  ota_file *p = (ota_file*)pFile;
  ota_vfs *pOtaVfs = p->pOtaVfs;
  int rc = p->pReal->pMethods->xRead(p->pReal, zBuf, iAmt, iOfst);
  if( rc==SQLITE_OK && p==pOtaVfs->pTargetDb && iOfst==0 ){
    unsigned char *pBuf = (unsigned char*)zBuf;
    assert( iAmt>=100 );
    pOtaVfs->pOta->iCookie = otaGetU32(&pBuf[24]);
  }
  return rc;
}

/*
** Write data to an otaVfs-file.
*/
................................................................................
static int otaVfsWrite(
  sqlite3_file *pFile, 
  const void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  ota_file *p = (ota_file*)pFile;
  ota_vfs *pOtaVfs = p->pOtaVfs;
  int rc = p->pReal->pMethods->xWrite(p->pReal, zBuf, iAmt, iOfst);
  if( rc==SQLITE_OK && p==pOtaVfs->pTargetDb && iOfst==0 ){
    unsigned char *pBuf = (unsigned char*)zBuf;
    assert( iAmt>=100 );
    pOtaVfs->pOta->iCookie = otaGetU32(&pBuf[24]);
  }
  return rc;
}

/*
** Truncate an otaVfs-file.
*/
................................................................................
}

/*
** Lock an otaVfs-file.
*/
static int otaVfsLock(sqlite3_file *pFile, int eLock){
  ota_file *p = (ota_file*)pFile;
  ota_vfs *pOtaVfs = p->pOtaVfs;
  int rc = SQLITE_OK;
  int eStage = pOtaVfs->pOta->eStage;

  if( pOtaVfs->pTargetDb==p 
   && (eStage==OTA_STAGE_OAL || eStage==OTA_STAGE_CKPT) 
   && eLock==SQLITE_LOCK_EXCLUSIVE

  ){
    /* Do not allow EXCLUSIVE locks. Preventing SQLite from taking this 
    ** prevents it from checkpointing the database from sqlite3_close(). */
    rc = SQLITE_BUSY;
  }else{
    rc = p->pReal->pMethods->xLock(p->pReal, eLock);
  }
................................................................................
}

/*
** File control method. For custom operations on an otaVfs-file.
*/
static int otaVfsFileControl(sqlite3_file *pFile, int op, void *pArg){
  ota_file *p = (ota_file *)pFile;






  return p->pReal->pMethods->xFileControl(p->pReal, op, pArg);
}

/*
** Return the sector-size in bytes for an otaVfs-file.
*/
static int otaVfsSectorSize(sqlite3_file *pFile){
................................................................................
}

/*
** Shared-memory methods are all pass-thrus.
*/
static int otaVfsShmLock(sqlite3_file *pFile, int ofst, int n, int flags){
  ota_file *p = (ota_file*)pFile;
  ota_vfs *pOtaVfs = p->pOtaVfs;
  int rc = SQLITE_OK;

#ifdef SQLITE_AMALGAMATION
    assert( WAL_WRITE_CKPT==1 );
#endif

  if( pOtaVfs->pTargetDb==p && pOtaVfs->pOta->eStage==OTA_STAGE_OAL ){
    /* Magic number 1 is the WAL_WRITE_CKPT lock. Preventing SQLite from
    ** taking this lock also prevents any checkpoints from occurring. 
    ** todo: really, it's not clear why this might occur, as 
    ** wal_autocheckpoint ought to be turned off.  */
    if( ofst==1 && n==1 ) rc = SQLITE_BUSY;
  }else{
    assert( p->nShm==0 );
    return p->pReal->pMethods->xShmLock(p->pReal, ofst, n, flags);
  }

  return rc;
}

static int otaVfsShmMap(
  sqlite3_file *pFile, 
  int iRegion, 
  int szRegion, 
  int isWrite, 
  void volatile **pp
){
  ota_file *p = (ota_file*)pFile;
  ota_vfs *pOtaVfs = p->pOtaVfs;
  int rc = SQLITE_OK;

  /* If not in OTA_STAGE_OAL, allow this call to pass through. Or, if this
  ** ota is in the OTA_STAGE_OAL state, use heap memory for *-shm space 
  ** instead of a file on disk.  */
  if( pOtaVfs->pTargetDb==p && pOtaVfs->pOta->eStage==OTA_STAGE_OAL ){
    if( iRegion<=p->nShm ){
      int nByte = (iRegion+1) * sizeof(char*);
      char **apNew = (char**)sqlite3_realloc(p->apShm, nByte);
      if( apNew==0 ){
        rc = SQLITE_NOMEM;
      }else{
        memset(&apNew[p->nShm], 0, sizeof(char*) * (1 + iRegion - p->nShm));
................................................................................
static void otaVfsShmBarrier(sqlite3_file *pFile){
  ota_file *p = (ota_file *)pFile;
  p->pReal->pMethods->xShmBarrier(p->pReal);
}

static int otaVfsShmUnmap(sqlite3_file *pFile, int delFlag){
  ota_file *p = (ota_file*)pFile;
  ota_vfs *pOtaVfs = p->pOtaVfs;
  int rc = SQLITE_OK;

  if( pOtaVfs->pTargetDb==p && pOtaVfs->pOta->eStage==OTA_STAGE_OAL ){
    /* no-op */
  }else{
    rc = p->pReal->pMethods->xShmUnmap(p->pReal, delFlag);
  }
  return rc;
}


static int otaVfsIswal(ota_vfs *pOtaVfs, const char *zPath){
  int nPath = strlen(zPath);
  int nTargetDb = strlen(pOtaVfs->zTargetDb);
  return ( nPath==(nTargetDb+4) 
        && 0==memcmp(zPath, pOtaVfs->zTargetDb, nTargetDb)
        && 0==memcmp(&zPath[nTargetDb], "-wal", 4)
  );
}


/*
** Open an ota file handle.
*/
static int otaVfsOpen(
  sqlite3_vfs *pVfs,
  const char *zName,
................................................................................
    otaVfsShmMap,                 /* xShmMap */
    otaVfsShmLock,                /* xShmLock */
    otaVfsShmBarrier,             /* xShmBarrier */
    otaVfsShmUnmap                /* xShmUnmap */
  };
  ota_vfs *pOtaVfs = (ota_vfs*)pVfs;
  sqlite3_vfs *pRealVfs = pOtaVfs->pRealVfs;
  sqlite3ota *p = pOtaVfs->pOta;
  ota_file *pFd = (ota_file *)pFile;
  int rc = SQLITE_OK;
  const char *zOpen = zName;

  memset(pFd, 0, sizeof(ota_file));
  pFd->pReal = (sqlite3_file*)&pFd[1];
  pFd->pOtaVfs = pOtaVfs;
















  if( zName && p->eStage==OTA_STAGE_OAL && otaVfsIswal(pOtaVfs, zName) ){










    char *zCopy = otaStrndup(zName, -1, &rc);
    if( zCopy ){
      int nCopy = strlen(zCopy);
      zCopy[nCopy-3] = 'o';
      zOpen = (const char*)(pFd->zFilename = zCopy);

    }
  }

  if( rc==SQLITE_OK ){
    rc = pRealVfs->xOpen(pRealVfs, zOpen, pFd->pReal, flags, pOutFlags);
  }
  if( pFd->pReal->pMethods ){
    pFile->pMethods = &otavfs_io_methods;
    if( pOtaVfs->pTargetDb==0 ){
      /* This is the target db file. */
      assert( (flags & SQLITE_OPEN_MAIN_DB) );
      assert( zOpen==zName );
      pOtaVfs->pTargetDb = pFd;
      pOtaVfs->zTargetDb = zName;
    }
  }

  return rc;
}

/*
** Delete the file located at zPath.
................................................................................
){
  ota_vfs *pOtaVfs = (ota_vfs*)pVfs;
  sqlite3_vfs *pRealVfs = pOtaVfs->pRealVfs;
  int rc;

  rc = pRealVfs->xAccess(pRealVfs, zPath, flags, pResOut);

  if( rc==SQLITE_OK 
   && flags==SQLITE_ACCESS_EXISTS 
   && pOtaVfs->pOta->eStage==OTA_STAGE_OAL 
   && otaVfsIswal(pOtaVfs, zPath) 
  ){
    if( *pResOut ){
      rc = SQLITE_CANTOPEN;
    }else{
      *pResOut = 1;
    }
  }

................................................................................
  return pRealVfs->xCurrentTime(pRealVfs, pTimeOut);
}

static int otaVfsGetLastError(sqlite3_vfs *pVfs, int a, char *b){
  return 0;
}









static void otaCreateVfs(sqlite3ota *p, const char *zParent){

  /* Template for VFS */
  static sqlite3_vfs vfs_template = {
    1,                            /* iVersion */
    0,                            /* szOsFile */
    0,                            /* mxPathname */
    0,                            /* pNext */
................................................................................
    otaVfsGetLastError,           /* xGetLastError */
    0,                            /* xCurrentTimeInt64 (version 2) */
    0, 0, 0                       /* Unimplemented version 3 methods */
  };

  sqlite3_vfs *pParent;           /* Parent VFS */
  ota_vfs *pNew = 0;              /* Newly allocated VFS */



  assert( p->rc==SQLITE_OK );

  pParent = sqlite3_vfs_find(zParent);
  if( pParent==0 ){
    p->rc = SQLITE_ERROR;
    p->zErrmsg = sqlite3_mprintf("no such vfs: %s", zParent);
  }else{
    int nByte = sizeof(ota_vfs) + 64;
    pNew = (ota_vfs*)otaMalloc(p, nByte);




  }

  if( pNew ){
    int rnd;


    char *zName;
    memcpy(&pNew->base, &vfs_template, sizeof(sqlite3_vfs));
    pNew->base.mxPathname = pParent->mxPathname;
    pNew->base.szOsFile = sizeof(ota_file) + pParent->szOsFile;
    pNew->pOta = p;
    pNew->pRealVfs = pParent;

    /* Give the new VFS a unique name */
    sqlite3_randomness(sizeof(int), (void*)&rnd);
    pNew->base.zName = (const char*)(zName = (char*)&pNew[1]);
    sprintf(zName, "ota_vfs_%d", rnd);


    /* Register the new VFS (not as the default) */
    assert( p->rc==SQLITE_OK );
    p->rc = sqlite3_vfs_register(&pNew->base, 0);
    if( p->rc ){
      p->zErrmsg = sqlite3_mprintf("error in sqlite3_vfs_register()");
      sqlite3_free(pNew);
    }else{






      p->pVfs = &pNew->base;


    }










  }
}

static void otaDeleteVfs(sqlite3ota *p){
  if( p->pVfs ){
    sqlite3_vfs_unregister(p->pVfs);
    sqlite3_free(p->pVfs);
    p->pVfs = 0;


  }
}


/**************************************************************************/

#ifdef SQLITE_TEST 

#define OTA_CREATE_STATE "CREATE TABLE IF NOT EXISTS ota.ota_state"        \
                             "(k INTEGER PRIMARY KEY, v)"

typedef struct OtaState OtaState;
typedef struct OtaObjIter OtaObjIter;
typedef struct ota_vfs ota_vfs;
typedef struct ota_file ota_file;

/*
** A structure to store values read from the ota_state table in memory.
*/
struct OtaState {
  int eStage;
  char *zTbl;
................................................................................
*/
#define OTA_PK_NOTABLE        0
#define OTA_PK_NONE           1
#define OTA_PK_IPK            2
#define OTA_PK_EXTERNAL       3
#define OTA_PK_WITHOUT_ROWID  4
#define OTA_PK_VTAB           5


/*
** OTA handle.
*/
struct sqlite3ota {
  int eStage;                     /* Value of OTA_STATE_STAGE field */
  sqlite3 *db;                    /* "main" -> target db, "ota" -> ota db */
................................................................................
  char *zOta;                     /* Path to ota db */
  int rc;                         /* Value returned by last ota_step() call */
  char *zErrmsg;                  /* Error message if rc!=SQLITE_OK */
  int nStep;                      /* Rows processed for current object */
  int nProgress;                  /* Rows processed for all objects */
  OtaObjIter objiter;             /* Iterator for skipping through tbl/idx */
  sqlite3_ckpt *pCkpt;            /* Incr-checkpoint handle */
  ota_file *pTargetFd;            /* File handle open on target db */
  const char *zVfsName;           /* Name of automatically created ota vfs */
  unsigned int iCookie;
};

struct ota_vfs {
  sqlite3_vfs base;             /* ota VFS shim methods */
  sqlite3_vfs *pRealVfs;        /* Underlying VFS */
  sqlite3_mutex *mutex;
  const char *zOtaWal;
};

struct ota_file {
  sqlite3_file base;              /* sqlite3_file methods */
  sqlite3_file *pReal;            /* Underlying file handle */
  ota_vfs *pOtaVfs;               /* Pointer to the ota_vfs object */
  sqlite3ota *pOta;               /* Pointer to ota object (ota target only) */

  int nShm;                       /* Number of entries in apShm[] array */
  char **apShm;                   /* Array of mmap'd *-shm regions */
  const char *zWal;               /* Wal filename for this db file */
  char *zDel;                     /* Delete this when closing file */
};


static void otaCreateVfs(sqlite3ota*, const char*);
static void otaDeleteVfs(sqlite3ota*);

/*
** Prepare the SQL statement in buffer zSql against database handle db.
** If successful, set *ppStmt to point to the new statement and return
................................................................................
      p->rc = sqlite3_exec(p->db, zSql, 0, 0, &p->zErrmsg);
      sqlite3_free(zSql);
    }
  }
  va_end(ap);
  return p->rc;
}

static void *otaMalloc(sqlite3ota *p, int nByte){
  void *pRet = 0;
  if( p->rc==SQLITE_OK ){
    pRet = sqlite3_malloc(nByte);
    if( pRet==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
      memset(pRet, 0, nByte);
    }
  }
  return pRet;
}


/*
** Allocate and zero the pIter->azTblCol[] and abTblPk[] arrays so that
** there is room for at least nCol elements. If an OOM occurs, store an
** error code in the OTA handle passed as the first argument.
*/
static void otaAllocateIterArrays(sqlite3ota *p, OtaObjIter *pIter, int nCol){
  int nByte = (2*sizeof(char*) + sizeof(int) + 2*sizeof(unsigned char)) * nCol;
  char **azNew;


  azNew = (char**)otaMalloc(p, nByte);
  if( azNew ){

    pIter->azTblCol = azNew;
    pIter->azTblType = &azNew[nCol];
    pIter->aiSrcOrder = (int*)&pIter->azTblType[nCol];
    pIter->abTblPk = (unsigned char*)&pIter->aiSrcOrder[nCol];
    pIter->abNotNull = (unsigned char*)&pIter->abTblPk[nCol];


  }
}

static char *otaStrndup(const char *zStr, int nStr, int *pRc){
  char *zRet = 0;
  assert( *pRc==SQLITE_OK );

................................................................................
    sqlite3_free(zSql);
    zSql = 0;
  }
  va_end(ap);
  return zSql;
}














/*
** This function constructs and returns a pointer to a nul-terminated 
** string containing some SQL clause or list based on one or more of the 
** column names currently stored in the pIter->azTblCol[] array.
*/
static char *otaObjIterGetCollist(
  sqlite3ota *p,                  /* OTA object */
................................................................................
    }
  }
  return zList;
}

static char *otaObjIterGetBindlist(sqlite3ota *p, int nBind){
  char *zRet = 0;

  int nByte = nBind*2 + 1;

  zRet = (char*)otaMalloc(p, nByte);
  if( zRet ){


    int i;
    for(i=0; i<nBind; i++){
      zRet[i*2] = '?';
      zRet[i*2+1] = (i+1==nBind) ? '\0' : ',';

    }
  }
  return zRet;
}

/*
** The iterator currently points to a table (not index) of type 
................................................................................
** error occurs, leave an error code and message in the OTA handle.
*/
static void otaOpenDatabase(sqlite3ota *p){
  int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE;
  assert( p->rc==SQLITE_OK );
  assert( p->db==0 );

  p->rc = sqlite3_open_v2(p->zTarget, &p->db, flags, p->zVfsName);
  if( p->rc ){
    p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(p->db));
  }else{
    /* Mark the database file just opened as an OTA target database. If 
    ** this call returns SQLITE_NOTFOUND, then the OTA vfs is not in use.
    ** This is an error.  */
    p->rc = sqlite3_file_control(p->db, "main", SQLITE_FCNTL_OTA, (void*)p);
    if( p->rc==SQLITE_NOTFOUND ){
      p->rc = SQLITE_ERROR;
      p->zErrmsg = sqlite3_mprintf("ota vfs not found");
    }else{
      otaMPrintfExec(p, "ATTACH %Q AS ota", p->zOta);
    }
  }
}

/*
** This routine is a copy of the sqlite3FileSuffix3() routine from the core.
** It is a no-op unless SQLITE_ENABLE_8_3_NAMES is defined.
**
** If SQLITE_ENABLE_8_3_NAMES is set at compile-time and if the database
................................................................................
        p->nProgress = pState->nProgress;
      }
    }
    assert( p->rc!=SQLITE_OK || p->eStage!=0 );

    if( p->rc==SQLITE_OK ){
      if( p->eStage==OTA_STAGE_OAL ){
        ota_vfs *pOtaVfs = p->pTargetFd->pOtaVfs;



        sqlite3_mutex_enter(pOtaVfs->mutex);
        assert( pOtaVfs->zOtaWal==0 );
        pOtaVfs->zOtaWal = p->pTargetFd->zWal;
        p->rc = sqlite3_exec(p->db, "BEGIN IMMEDIATE", 0, 0, &p->zErrmsg);
        pOtaVfs->zOtaWal = 0;
        sqlite3_mutex_leave(pOtaVfs->mutex);
  
        /* Point the object iterator at the first object */
        if( p->rc==SQLITE_OK ){
          p->rc = otaObjIterFirst(p, &p->objiter);
        }
  
        if( p->rc==SQLITE_OK ){
................................................................................
**           non-zero (to tell SQLite that it does exist) anyway.
**
**   5. In OTA_STAGE_OAL mode, if SQLite tries to open a *-wal file 
**      associated with a target database, open the corresponding *-oal file
**      instead.
*/






















/*
** Close an ota file.
*/
static int otaVfsClose(sqlite3_file *pFile){
  ota_file *p = (ota_file*)pFile;

  int rc;
  int i;

  /* Free the contents of the apShm[] array. And the array itself. */
  for(i=0; i<p->nShm; i++){
    sqlite3_free(p->apShm[i]);
  }
  sqlite3_free(p->apShm);
  p->apShm = 0;
  sqlite3_free(p->zDel);






  rc = p->pReal->pMethods->xClose(p->pReal);
  return rc;
}


/*
................................................................................
static int otaVfsRead(
  sqlite3_file *pFile, 
  void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  ota_file *p = (ota_file*)pFile;

  int rc = p->pReal->pMethods->xRead(p->pReal, zBuf, iAmt, iOfst);
  if( rc==SQLITE_OK && p->pOta && iOfst==0 ){
    unsigned char *pBuf = (unsigned char*)zBuf;
    assert( iAmt>=100 );
    p->pOta->iCookie = otaGetU32(&pBuf[24]);
  }
  return rc;
}

/*
** Write data to an otaVfs-file.
*/
................................................................................
static int otaVfsWrite(
  sqlite3_file *pFile, 
  const void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  ota_file *p = (ota_file*)pFile;

  int rc = p->pReal->pMethods->xWrite(p->pReal, zBuf, iAmt, iOfst);
  if( rc==SQLITE_OK && p->pOta && iOfst==0 ){
    unsigned char *pBuf = (unsigned char*)zBuf;
    assert( iAmt>=100 );
    p->pOta->iCookie = otaGetU32(&pBuf[24]);
  }
  return rc;
}

/*
** Truncate an otaVfs-file.
*/
................................................................................
}

/*
** Lock an otaVfs-file.
*/
static int otaVfsLock(sqlite3_file *pFile, int eLock){
  ota_file *p = (ota_file*)pFile;
  sqlite3ota *pOta = p->pOta;
  int rc = SQLITE_OK;




  if( pOta && eLock==SQLITE_LOCK_EXCLUSIVE
   && (pOta->eStage==OTA_STAGE_OAL || pOta->eStage==OTA_STAGE_CKPT) 
  ){
    /* Do not allow EXCLUSIVE locks. Preventing SQLite from taking this 
    ** prevents it from checkpointing the database from sqlite3_close(). */
    rc = SQLITE_BUSY;
  }else{
    rc = p->pReal->pMethods->xLock(p->pReal, eLock);
  }
................................................................................
}

/*
** File control method. For custom operations on an otaVfs-file.
*/
static int otaVfsFileControl(sqlite3_file *pFile, int op, void *pArg){
  ota_file *p = (ota_file *)pFile;
  if( op==SQLITE_FCNTL_OTA ){
    sqlite3ota *pOta = (sqlite3ota*)pArg;
    pOta->pTargetFd = p;
    p->pOta = pOta;
    return SQLITE_OK;
  }
  return p->pReal->pMethods->xFileControl(p->pReal, op, pArg);
}

/*
** Return the sector-size in bytes for an otaVfs-file.
*/
static int otaVfsSectorSize(sqlite3_file *pFile){
................................................................................
}

/*
** Shared-memory methods are all pass-thrus.
*/
static int otaVfsShmLock(sqlite3_file *pFile, int ofst, int n, int flags){
  ota_file *p = (ota_file*)pFile;

  int rc = SQLITE_OK;

#ifdef SQLITE_AMALGAMATION
    assert( WAL_WRITE_CKPT==1 );
#endif

  if( p->pOta && p->pOta->eStage==OTA_STAGE_OAL ){
    /* Magic number 1 is the WAL_WRITE_CKPT lock. Preventing SQLite from
    ** taking this lock also prevents any checkpoints from occurring. 
    ** todo: really, it's not clear why this might occur, as 
    ** wal_autocheckpoint ought to be turned off.  */
    if( ofst==1 && n==1 ) rc = SQLITE_BUSY;
  }else{
    assert( p->nShm==0 );
    rc = p->pReal->pMethods->xShmLock(p->pReal, ofst, n, flags);
  }

  return rc;
}

static int otaVfsShmMap(
  sqlite3_file *pFile, 
  int iRegion, 
  int szRegion, 
  int isWrite, 
  void volatile **pp
){
  ota_file *p = (ota_file*)pFile;

  int rc = SQLITE_OK;

  /* If not in OTA_STAGE_OAL, allow this call to pass through. Or, if this
  ** ota is in the OTA_STAGE_OAL state, use heap memory for *-shm space 
  ** instead of a file on disk.  */
  if( p->pOta && p->pOta->eStage==OTA_STAGE_OAL ){
    if( iRegion<=p->nShm ){
      int nByte = (iRegion+1) * sizeof(char*);
      char **apNew = (char**)sqlite3_realloc(p->apShm, nByte);
      if( apNew==0 ){
        rc = SQLITE_NOMEM;
      }else{
        memset(&apNew[p->nShm], 0, sizeof(char*) * (1 + iRegion - p->nShm));
................................................................................
static void otaVfsShmBarrier(sqlite3_file *pFile){
  ota_file *p = (ota_file *)pFile;
  p->pReal->pMethods->xShmBarrier(p->pReal);
}

static int otaVfsShmUnmap(sqlite3_file *pFile, int delFlag){
  ota_file *p = (ota_file*)pFile;

  int rc = SQLITE_OK;

  if( p->pOta && p->pOta->eStage==OTA_STAGE_OAL ){
    /* no-op */
  }else{
    rc = p->pReal->pMethods->xShmUnmap(p->pReal, delFlag);
  }
  return rc;
}












/*
** Open an ota file handle.
*/
static int otaVfsOpen(
  sqlite3_vfs *pVfs,
  const char *zName,
................................................................................
    otaVfsShmMap,                 /* xShmMap */
    otaVfsShmLock,                /* xShmLock */
    otaVfsShmBarrier,             /* xShmBarrier */
    otaVfsShmUnmap                /* xShmUnmap */
  };
  ota_vfs *pOtaVfs = (ota_vfs*)pVfs;
  sqlite3_vfs *pRealVfs = pOtaVfs->pRealVfs;

  ota_file *pFd = (ota_file *)pFile;
  int rc = SQLITE_OK;
  const char *zOpen = zName;

  memset(pFd, 0, sizeof(ota_file));
  pFd->pReal = (sqlite3_file*)&pFd[1];
  pFd->pOtaVfs = pOtaVfs;
  if( zName ){
    if( flags & SQLITE_OPEN_MAIN_DB ){
      /* A main database has just been opened. The following block sets
      ** (pFd->zWal) to point to a buffer owned by SQLite that contains
      ** the name of the *-wal file this db connection will use. SQLite
      ** happens to pass a pointer to this buffer when using xAccess()
      ** or xOpen() to operate on the *-wal file.  */
      int n = strlen(zName);
      const char *z = &zName[n];
      if( flags & SQLITE_OPEN_URI ){
        int odd = 0;
        while( 1 ){
          if( z[0]==0 ){
            odd = 1 - odd;
            if( odd && z[1]==0 ) break;
          }

          z++;
        }
        z += 2;
      }else{
        while( *z==0 ) z++;
      }
      z += (n + 8 + 1);
      pFd->zWal = z;
    }
    else if( (flags & SQLITE_OPEN_WAL) && zName==pOtaVfs->zOtaWal ){
      char *zCopy = otaStrndup(zName, -1, &rc);
      if( zCopy ){
        int nCopy = strlen(zCopy);
        zCopy[nCopy-3] = 'o';
        zOpen = (const char*)(pFd->zDel = zCopy);
      }
    }
  }

  if( rc==SQLITE_OK ){
    rc = pRealVfs->xOpen(pRealVfs, zOpen, pFd->pReal, flags, pOutFlags);
  }
  if( pFd->pReal->pMethods ){
    pFile->pMethods = &otavfs_io_methods;







  }

  return rc;
}

/*
** Delete the file located at zPath.
................................................................................
){
  ota_vfs *pOtaVfs = (ota_vfs*)pVfs;
  sqlite3_vfs *pRealVfs = pOtaVfs->pRealVfs;
  int rc;

  rc = pRealVfs->xAccess(pRealVfs, zPath, flags, pResOut);


  if( rc==SQLITE_OK && flags==SQLITE_ACCESS_EXISTS && pOtaVfs->zOtaWal==zPath ){



    if( *pResOut ){
      rc = SQLITE_CANTOPEN;
    }else{
      *pResOut = 1;
    }
  }

................................................................................
  return pRealVfs->xCurrentTime(pRealVfs, pTimeOut);
}

static int otaVfsGetLastError(sqlite3_vfs *pVfs, int a, char *b){
  return 0;
}

void sqlite3ota_destroy_vfs(const char *zName){
  sqlite3_vfs *pVfs = sqlite3_vfs_find(zName);
  if( pVfs ){
    sqlite3_vfs_unregister(pVfs);
    sqlite3_free(pVfs);
  }
}

int sqlite3ota_create_vfs(const char *zName, const char *zParent){

  /* Template for VFS */
  static sqlite3_vfs vfs_template = {
    1,                            /* iVersion */
    0,                            /* szOsFile */
    0,                            /* mxPathname */
    0,                            /* pNext */
................................................................................
    otaVfsGetLastError,           /* xGetLastError */
    0,                            /* xCurrentTimeInt64 (version 2) */
    0, 0, 0                       /* Unimplemented version 3 methods */
  };

  sqlite3_vfs *pParent;           /* Parent VFS */
  ota_vfs *pNew = 0;              /* Newly allocated VFS */
  int nName;
  int rc = SQLITE_OK;


  nName = strlen(zName);
  pParent = sqlite3_vfs_find(zParent);
  if( pParent==0 ){
    rc = SQLITE_NOTFOUND;

  }else{
    int nByte = sizeof(ota_vfs) + nName + 1;
    pNew = (ota_vfs*)sqlite3_malloc(nByte);
    if( pNew==0 ){
      rc = SQLITE_NOMEM;
    }else{
      memset(pNew, 0, nByte);
    }
  }



  if( rc==SQLITE_OK ){
    char *zSpace;
    memcpy(&pNew->base, &vfs_template, sizeof(sqlite3_vfs));
    pNew->base.mxPathname = pParent->mxPathname;
    pNew->base.szOsFile = sizeof(ota_file) + pParent->szOsFile;

    pNew->pRealVfs = pParent;



    pNew->base.zName = (const char*)(zSpace = (char*)&pNew[1]);

    memcpy(zSpace, zName, nName);

    /* Register the new VFS (not as the default) */

    rc = sqlite3_vfs_register(&pNew->base, 0);
    if( rc ){

      sqlite3_free(pNew);

    }
  }

  return rc;
}

static void otaCreateVfs(sqlite3ota *p, const char *zParent){
  int rnd;
  char zRnd[64];

  assert( p->rc==SQLITE_OK );
  sqlite3_randomness(sizeof(int), (void*)&rnd);
  sprintf(zRnd, "ota_vfs_%d", rnd);
  p->rc = sqlite3ota_create_vfs(zRnd, zParent);
  if( p->rc==SQLITE_NOTFOUND ){
    p->zErrmsg = sqlite3_mprintf("no such vfs: %s", zParent);
  }else if( p->rc==SQLITE_OK ){
    sqlite3_vfs *pVfs = sqlite3_vfs_find(zRnd);
    assert( pVfs );
    p->zVfsName = pVfs->zName;
  }
}

static void otaDeleteVfs(sqlite3ota *p){
  if( p->zVfsName ){



    sqlite3ota_destroy_vfs(p->zVfsName);
    p->zVfsName = 0;
  }
}


/**************************************************************************/

#ifdef SQLITE_TEST 

/*
** Return the total number of key-value operations (inserts, deletes or 
** updates) that have been performed on the target database since the
** current OTA update was started.
*/
sqlite3_int64 sqlite3ota_progress(sqlite3ota *pOta);

















#endif /* _SQLITE3OTA_H */

/*
** Return the total number of key-value operations (inserts, deletes or 
** updates) that have been performed on the target database since the
** current OTA update was started.
*/
sqlite3_int64 sqlite3ota_progress(sqlite3ota *pOta);

/*
** Create an OTA VFS named zName. Use existing VFS zParent to interact
** with the file-system.
*/
int sqlite3ota_create_vfs(const char *zName, const char *zParent);

/*
** Deregister and destroy an OTA vfs previously created by 
** sqlite3ota_create_vfs().
**
** VFS objects are not reference counted. If a VFS object is destroyed
** before all database handles that use it have been closed, the results 
** are undefined.
*/
void sqlite3ota_destroy_vfs(const char *zName);

#endif /* _SQLITE3OTA_H */

#define SQLITE_FCNTL_MMAP_SIZE              18
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
#define SQLITE_FCNTL_ZIPVFS_PAGER           24


/*
** 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

#define SQLITE_FCNTL_MMAP_SIZE              18
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
#define SQLITE_FCNTL_ZIPVFS_PAGER           24
#define SQLITE_FCNTL_OTA                    25

/*
** 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