return $filename
}

# Run the OTA in file $ota on target database $target until completion.
#
proc run_ota {target ota} {
  sqlite3ota ota $target $ota

  while { [ota step]=="SQLITE_OK" } {}


  ota close
}

proc step_ota {target ota} {
  while 1 {
    sqlite3ota ota $target $ota
    set rc [ota step]

  return $filename
}

# Run the OTA in file $ota on target database $target until completion.
#
proc run_ota {target ota} {
  sqlite3ota ota $target $ota
  while 1 {
    set rc [ota step]
    if {$rc!="SQLITE_OK"} break
  }
  ota close
}

proc step_ota {target ota} {
  while 1 {
    sqlite3ota ota $target $ota
    set rc [ota step]

/*
** The ota_state table is used to save the state of a partially applied
** update so that it can be resumed later. The table consists of integer
** keys mapped to values as follows:
**
** OTA_STATE_STAGE:
**   May be set to integer values 1, 2 or 3. As follows:
**       0: Nothing at all has been done.
**       1: the *-ota file is currently under construction.
**       2: the *-ota file has been constructed, but not yet moved 
**          to the *-wal path.
**       3: the checkpoint is underway.

**
** OTA_STATE_TBL:
**   Only valid if STAGE==1. The target database name of the table 
**   currently being written.
**
** OTA_STATE_IDX:
**   Only valid if STAGE==1. The target database name of the index 
................................................................................
**   table/index.
**
** OTA_STATE_PROGRESS:
**   Total number of sqlite3ota_step() calls made so far as part of this
**   ota update.
**
** OTA_STATE_CKPT:
**   Valid if STAGE==3. The blob to pass to sqlite3ckpt_start() to resume


**   the incremental checkpoint.

**
** OTA_STATE_COOKIE:
**   Valid if STAGE==1. The current change-counter cookie value in the 
**   target db file.
*/
#define OTA_STATE_STAGE       1
#define OTA_STATE_TBL         2
................................................................................
#define OTA_STAGE_CKPT        4
#define OTA_STAGE_DONE        5


#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;

#if !defined(SQLITE_AMALGAMATION)
typedef unsigned int u32;
typedef unsigned char u8;
typedef sqlite3_int64 i64;
................................................................................
  /* Output variables. zTbl==0 implies EOF. */
  int bCleanup;                   /* True in "cleanup" state */
  const char *zTbl;               /* Name of target db table */
  const char *zIdx;               /* Name of target db index (or null) */
  int iTnum;                      /* Root page of current object */
  int iPkTnum;                    /* If eType==EXTERNAL, root of PK index */
  int bUnique;                    /* Current index is unique */
  int iVisit;                     /* Number of points visited, incl. current */

  /* Statements created by otaObjIterPrepareAll() */
  int nCol;                       /* Number of columns in current object */
  sqlite3_stmt *pSelect;          /* Source data */
  sqlite3_stmt *pInsert;          /* Statement for INSERT operations */
  sqlite3_stmt *pDelete;          /* Statement for DELETE ops */

................................................................................
#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


typedef struct OtaFrame OtaFrame;















struct OtaFrame {
  u32 iDbPage;
  u32 iWalFrame;
};

/*
** OTA handle.
................................................................................
  int nFrameAlloc;                /* Allocated size of aFrame[] array */
  OtaFrame *aFrame;
  int pgsz;
  u8 *aBuf;
  i64 iWalCksum;
};




struct ota_vfs {
  sqlite3_vfs base;               /* ota VFS shim methods */
  sqlite3_vfs *pRealVfs;          /* Underlying VFS */
  sqlite3_mutex *mutex;           /* Mutex to protect pMain */
  ota_file *pMain;                /* Linked list of main db files */
};





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 openFlags;                  /* Flags this file was opened with */
................................................................................

    if( rc==SQLITE_OK ){
      if( pIter->bCleanup ){
        otaObjIterFreeCols(pIter);
        pIter->bCleanup = 0;
        rc = sqlite3_step(pIter->pTblIter);
        if( rc!=SQLITE_ROW ){
          rc = sqlite3_reset(pIter->pTblIter);
          pIter->zTbl = 0;
        }else{
          pIter->zTbl = (const char*)sqlite3_column_text(pIter->pTblIter, 0);
          pIter->iTnum = sqlite3_column_int(pIter->pTblIter, 1);
          rc = pIter->zTbl ? SQLITE_OK : SQLITE_NOMEM;
        }
      }else{
................................................................................
        if( pIter->zIdx==0 ){
          sqlite3_stmt *pIdx = pIter->pIdxIter;
          rc = sqlite3_bind_text(pIdx, 1, pIter->zTbl, -1, SQLITE_STATIC);
        }
        if( rc==SQLITE_OK ){
          rc = sqlite3_step(pIter->pIdxIter);
          if( rc!=SQLITE_ROW ){
            rc = sqlite3_reset(pIter->pIdxIter);
            pIter->bCleanup = 1;
            pIter->zIdx = 0;
          }else{
            pIter->zIdx = (const char*)sqlite3_column_text(pIter->pIdxIter, 0);
            pIter->iTnum = sqlite3_column_int(pIter->pIdxIter, 1);
            pIter->bUnique = sqlite3_column_int(pIter->pIdxIter, 2);
            rc = pIter->zIdx ? SQLITE_OK : SQLITE_NOMEM;
................................................................................
    }
  }

  if( rc!=SQLITE_OK ){
    otaObjIterFinalize(pIter);
    p->rc = rc;
  }
  pIter->iVisit++;
  return rc;
}

/*
** Initialize the iterator structure passed as the second argument.
**
** If no error occurs, SQLITE_OK is returned and the iterator is left 
................................................................................
    );
  }

  pIter->bCleanup = 1;
  p->rc = rc;
  return otaObjIterNext(p, pIter);
}

























/*
** Argument zFmt is a sqlite3_mprintf() style format string. The trailing
** arguments are the usual subsitution values. This function performs
** the printf() style substitutions and executes the result as an SQL
** statement on the OTA handles database.
**
................................................................................
** If an error occurs, an error code and error message is stored in the
** OTA handle. If an error has already occurred when this function is
** called, it is a no-op.
*/
static int otaMPrintfExec(sqlite3ota *p, const char *zFmt, ...){
  va_list ap;
  va_start(ap, zFmt);
  if( p->rc==SQLITE_OK ){
    char *zSql = sqlite3_vmprintf(zFmt, ap);

    if( zSql==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
      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{
................................................................................
    pIter->azTblType = &azNew[nCol];
    pIter->aiSrcOrder = (int*)&pIter->azTblType[nCol];
    pIter->abTblPk = (u8*)&pIter->aiSrcOrder[nCol];
    pIter->abNotNull = (u8*)&pIter->abTblPk[nCol];
  }
}











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

  assert( *pRc==SQLITE_OK );
  if( zStr ){
    int nCopy = strlen(zStr) + 1;
    zRet = (char*)sqlite3_malloc(nCopy);
................................................................................
    }else{
      *pRc = SQLITE_NOMEM;
    }
  }

  return zRet;
}

















/* Determine the type of a table.
**
**   peType is of type (int*), a pointer to an output parameter of type
**   (int). This call sets the output parameter as follows, depending
**   on the type of the table specified by parameters dbName and zTbl.
**
................................................................................
    }
    *peType = OTA_PK_NONE;
  }

otaTableType_end: {
    int i;
    for(i=0; i<sizeof(aStmt)/sizeof(aStmt[0]); i++){
      int rc2 = sqlite3_finalize(aStmt[i]);
      if( p->rc==SQLITE_OK ) p->rc = rc2;
    }
  }
}


/*
** If they are not already populated, populate the pIter->azTblCol[],
................................................................................
** the OTA handle.
*/
static int otaObjIterCacheTableInfo(sqlite3ota *p, OtaObjIter *pIter){
  if( pIter->azTblCol==0 ){
    sqlite3_stmt *pStmt = 0;
    int nCol = 0;
    int i;                        /* for() loop iterator variable */
    int rc2;                      /* sqlite3_finalize() return value */
    int bOtaRowid = 0;            /* If input table has column "ota_rowid" */
    int iOrder = 0;

    /* Figure out the type of table this step will deal with. */
    assert( pIter->eType==0 );
    otaTableType(p, pIter->zTbl, &pIter->eType, &pIter->iPkTnum);
    if( p->rc ) return p->rc;
................................................................................
        pIter->azTblType[iOrder] = otaStrndup(zType, &p->rc);
        pIter->abTblPk[iOrder] = (iPk!=0);
        pIter->abNotNull[iOrder] = (u8)bNotNull || (iPk!=0);
        iOrder++;
      }
    }

    rc2 = sqlite3_finalize(pStmt);
    if( p->rc==SQLITE_OK ) p->rc = rc2;
  }

  return p->rc;
}

/*
** This is a wrapper around "sqlite3_mprintf(zFmt, ...)". If an OOM occurs,
** an error code is stored in the OTA handle passed as the first argument.
**
** If an error has already occurred (p->rc is already set to something other
** than SQLITE_OK), then this function returns NULL without modifying the
** stored error code. In this case it still calls sqlite3_free() on any 
** printf() parameters associated with %z conversions.
*/
static char *otaMPrintf(sqlite3ota *p, const char *zFmt, ...){
  char *zSql = 0;
  va_list ap;
  va_start(ap, zFmt);
  zSql = sqlite3_vmprintf(zFmt, ap);
  if( p->rc==SQLITE_OK ){
    if( zSql==0 ) p->rc = SQLITE_NOMEM;
  }else{
    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 */
................................................................................
*/
static void otaBadControlError(sqlite3ota *p){
  p->rc = SQLITE_ERROR;
  p->zErrmsg = sqlite3_mprintf("invalid ota_control value");
}



















static char *otaObjIterGetSetlist(
  sqlite3ota *p,
  OtaObjIter *pIter,
  const char *zMask
){
  char *zList = 0;
  if( p->rc==SQLITE_OK ){
................................................................................
        }
      }
    }
  }
  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;
................................................................................
static char *otaWithoutRowidPK(sqlite3ota *p, OtaObjIter *pIter){
  char *z = 0;
  assert( pIter->zIdx==0 );
  if( p->rc==SQLITE_OK ){
    const char *zSep = "PRIMARY KEY(";
    sqlite3_stmt *pXList = 0;     /* PRAGMA index_list = (pIter->zTbl) */
    sqlite3_stmt *pXInfo = 0;     /* PRAGMA index_xinfo = <pk-index> */
    int rc;                       /* sqlite3_finalize() return code */

   
    p->rc = prepareFreeAndCollectError(p->db, &pXList, &p->zErrmsg,
        sqlite3_mprintf("PRAGMA main.index_list = %Q", pIter->zTbl)
    );
    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXList) ){
      const char *zOrig = (const char*)sqlite3_column_text(pXList,3);
      if( zOrig && strcmp(zOrig, "pk")==0 ){
................................................................................
          p->rc = prepareFreeAndCollectError(p->db, &pXInfo, &p->zErrmsg,
              sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
          );
        }
        break;
      }
    }
    rc = sqlite3_finalize(pXList);
    if( p->rc==SQLITE_OK ) p->rc = rc;

    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      if( sqlite3_column_int(pXInfo, 5) ){
        /* int iCid = sqlite3_column_int(pXInfo, 0); */
        const char *zCol = (const char*)sqlite3_column_text(pXInfo, 2);
        const char *zDesc = sqlite3_column_int(pXInfo, 3) ? " DESC" : "";
        z = otaMPrintf(p, "%z%s\"%w\"%s", z, zSep, zCol, zDesc);
        zSep = ", ";
      }
    }
    z = otaMPrintf(p, "%z)", z);
    rc = sqlite3_finalize(pXInfo);
    if( p->rc==SQLITE_OK ) p->rc = rc;
  }
  return z;
}

static void otaFinalize(sqlite3ota *p, sqlite3_stmt *pStmt){
  int rc = sqlite3_finalize(pStmt);
  if( p->rc==SQLITE_OK ) p->rc = rc;
}

/*
** This function creates the second imposter table used when writing to
** a table b-tree where the table has an external primary key. If the
** iterator passed as the second argument does not currently point to
** a table (not index) with an external primary key, this function is a
** no-op. 
**
................................................................................
*/
static void otaCreateImposterTable2(sqlite3ota *p, OtaObjIter *pIter){
  if( p->rc==SQLITE_OK && pIter->eType==OTA_PK_EXTERNAL ){
    int tnum = pIter->iPkTnum;    /* Root page of PK index */
    sqlite3_stmt *pQuery = 0;     /* SELECT name ... WHERE rootpage = $tnum */
    const char *zIdx = 0;         /* Name of PK index */
    sqlite3_stmt *pXInfo = 0;     /* PRAGMA main.index_xinfo = $zIdx */
    int rc;

    const char *zComma = "";

    char *zCols = 0;              /* Used to build up list of table cols */
    char *zPk = 0;                /* Used to build up table PK declaration */
    char *zSql = 0;               /* CREATE TABLE statement */

    /* Figure out the name of the primary key index for the current table.
    ** This is needed for the argument to "PRAGMA index_xinfo". Set
    ** zIdx to point to a nul-terminated string containing this name. */
    p->rc = prepareAndCollectError(p->db, &pQuery, &p->zErrmsg, 
        "SELECT name FROM sqlite_master WHERE rootpage = ?"
    );
................................................................................
            iCid, pIter->azTblType[iCid], zCollate
        );
        zPk = otaMPrintf(p, "%z%sc%d%s", zPk, zComma, iCid, bDesc?" DESC":"");
        zComma = ", ";
      }
    }
    zCols = otaMPrintf(p, "%z, id INTEGER", zCols);
    rc = sqlite3_finalize(pXInfo);
    if( p->rc==SQLITE_OK ) p->rc = rc;


    zSql = otaMPrintf(p, 
        "CREATE TABLE ota_imposter2(%z, PRIMARY KEY(%z)) WITHOUT ROWID", 
        zCols, zPk
    );
    assert( (zSql==0)==(p->rc!=SQLITE_OK) );
    if( zSql ){
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->db, "main", 1, tnum);
      p->rc = sqlite3_exec(p->db, zSql, 0, 0, &p->zErrmsg);
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->db, "main", 0, 0);
    }
    sqlite3_free(zSql);
  }
}

/*
** If an error has already occurred when this function is called, it 
** immediately returns zero (without doing any work). Or, if an error
** occurs during the execution of this function, it sets the error code
** in the sqlite3ota object indicated by the first argument and returns
** zero.
**
** The iterator passed as the second argument is guaranteed to point to
** a table (not an index) when this function is called. This function
** attempts to create any imposter tables required to write to the main
** table b-tree of the table before returning. Non-zero is returned if
** imposter tables are created, or zero otherwise.
**
** The required imposter tables depend on the type of table that the
** iterator currently points to.
**
**   OTA_PK_NONE, OTA_PK_IPK, OTA_PK_WITHOUT_ROWID:
**     A single imposter table is required. With the same schema as

**     the actual target table (less any UNIQUE constraints). More
**     precisely, the "same schema" means the same columns, types, collation
**     sequences and primary key declaration.
**
**   OTA_PK_VTAB:
**     No imposters required. 
**
**   OTA_PK_EXTERNAL:
**     Two imposters are required. The first has the same schema as the
**     target database table, with no PRIMARY KEY or UNIQUE clauses. The
**     second is used to access the PK b-tree index on disk.


*/
static void otaCreateImposterTable(sqlite3ota *p, OtaObjIter *pIter){
  if( p->rc==SQLITE_OK && pIter->eType!=OTA_PK_VTAB ){
    int tnum = pIter->iTnum;
    const char *zComma = "";
    char *zSql = 0;
    int iCol;
................................................................................
    if( pIter->eType==OTA_PK_WITHOUT_ROWID ){
      char *zPk = otaWithoutRowidPK(p, pIter);
      if( zPk ){
        zSql = otaMPrintf(p, "%z, %z", zSql, zPk);
      }
    }


    zSql = otaMPrintf(p, "CREATE TABLE \"ota_imp_%w\"(%z)%s", 
        pIter->zTbl, zSql, 
        (pIter->eType==OTA_PK_WITHOUT_ROWID ? " WITHOUT ROWID" : "")
    );
    if( p->rc==SQLITE_OK ){
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->db, "main", 1, tnum);
      p->rc = sqlite3_exec(p->db, zSql, 0, 0, &p->zErrmsg);
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->db, "main", 0, 0);
    }
    sqlite3_free(zSql);
  }
}

/*
** Ensure that the SQLite statement handles required to update the 
** target database object currently indicated by the iterator passed 
** as the second argument are available.
................................................................................
    sqlite3_free(zCollist);
    sqlite3_free(zLimit);
  }
  
  return p->rc;
}

#define OTA_INSERT     1

#define OTA_DELETE     2
#define OTA_IDX_DELETE 3
#define OTA_IDX_INSERT 4
#define OTA_UPDATE     5


static int otaGetUpdateStmt(
  sqlite3ota *p, 
  OtaObjIter *pIter, 
  const char *zMask,
  sqlite3_stmt **ppStmt
){
  if( pIter->pUpdate && strcmp(zMask, pIter->zMask)==0 ){
    *ppStmt = pIter->pUpdate;
  }else{
    char *zWhere = otaObjIterGetWhere(p, pIter);
    char *zSet = otaObjIterGetSetlist(p, pIter, zMask);
    char *zUpdate = 0;
................................................................................
      ** is already a transaction open, so the prepared statement cannot
      ** throw an SQLITE_SCHEMA exception. The only database page the
      ** statement reads is page 1, which is guaranteed to be in the cache.
      ** And no memory allocations are required.  */
      if( SQLITE_ROW==sqlite3_step(pStmt) ){
        iCookie = sqlite3_column_int(pStmt, 0);
      }
      p->rc = sqlite3_finalize(pStmt);
    }
    if( p->rc==SQLITE_OK ){
      otaMPrintfExec(p, "PRAGMA schema_version = %d", iCookie+1);
    }
  }
}

................................................................................
          OTA_STATE_TBL, p->objiter.zTbl, 
          OTA_STATE_IDX, p->objiter.zIdx, 
          OTA_STATE_ROW, p->nStep, 
          OTA_STATE_PROGRESS, p->nProgress,
          OTA_STATE_CKPT, p->iWalCksum,
          OTA_STATE_COOKIE, (i64)p->pTargetFd->iCookie
          )
        );
    assert( pInsert==0 || rc==SQLITE_OK );

    if( rc==SQLITE_OK ){
      sqlite3_step(pInsert);
      rc = sqlite3_finalize(pInsert);
    }else{
      sqlite3_finalize(pInsert);
    }

    if( rc!=SQLITE_OK ){
      p->rc = rc;
    }
  }
}


/*
** Step the OTA object.
*/
................................................................................
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 && pVfs->xOpen==otaVfsOpen ){

    sqlite3_vfs_unregister(pVfs);
    sqlite3_free(pVfs);
  }
}

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

................................................................................
      rc = SQLITE_NOTFOUND;
    }else{
      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!=SQLITE_OK ){
    sqlite3_free(pNew);
  }
  return rc;
}


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

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_OTA) */

/*
** The ota_state table is used to save the state of a partially applied
** update so that it can be resumed later. The table consists of integer
** keys mapped to values as follows:
**
** OTA_STATE_STAGE:
**   May be set to integer values 1, 2, 4 or 5. As follows:

**       1: the *-ota file is currently under construction.
**       2: the *-ota file has been constructed, but not yet moved 
**          to the *-wal path.
**       4: the checkpoint is underway.
**       5: the ota update has been checkpointed.
**
** OTA_STATE_TBL:
**   Only valid if STAGE==1. The target database name of the table 
**   currently being written.
**
** OTA_STATE_IDX:
**   Only valid if STAGE==1. The target database name of the index 
................................................................................
**   table/index.
**
** OTA_STATE_PROGRESS:
**   Total number of sqlite3ota_step() calls made so far as part of this
**   ota update.
**
** OTA_STATE_CKPT:
**   Valid if STAGE==4. The 64-bit checksum associated with the wal-index
**   header created by recovering the *-wal file. This is used to detect
**   cases when another client appends frames to the *-wal file in the
**   middle of an incremental checkpoint (an incremental checkpoint cannot
**   be continued if this happens).
**
** OTA_STATE_COOKIE:
**   Valid if STAGE==1. The current change-counter cookie value in the 
**   target db file.
*/
#define OTA_STATE_STAGE       1
#define OTA_STATE_TBL         2
................................................................................
#define OTA_STAGE_CKPT        4
#define OTA_STAGE_DONE        5


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

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

#if !defined(SQLITE_AMALGAMATION)
typedef unsigned int u32;
typedef unsigned char u8;
typedef sqlite3_int64 i64;
................................................................................
  /* Output variables. zTbl==0 implies EOF. */
  int bCleanup;                   /* True in "cleanup" state */
  const char *zTbl;               /* Name of target db table */
  const char *zIdx;               /* Name of target db index (or null) */
  int iTnum;                      /* Root page of current object */
  int iPkTnum;                    /* If eType==EXTERNAL, root of PK index */
  int bUnique;                    /* Current index is unique */


  /* Statements created by otaObjIterPrepareAll() */
  int nCol;                       /* Number of columns in current object */
  sqlite3_stmt *pSelect;          /* Source data */
  sqlite3_stmt *pInsert;          /* Statement for INSERT operations */
  sqlite3_stmt *pDelete;          /* Statement for DELETE ops */

................................................................................
#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



/*
** Within the OTA_STAGE_OAL stage, each call to sqlite3ota_step() performs
** one of the following operations.
*/
#define OTA_INSERT     1          /* Insert on a main table b-tree */
#define OTA_DELETE     2          /* Delete a row from a main table b-tree */
#define OTA_IDX_DELETE 3          /* Delete a row from an aux. index b-tree */
#define OTA_IDX_INSERT 4          /* Insert on an aux. index b-tree */
#define OTA_UPDATE     5          /* Update a row in a main table b-tree */


/*
** A single step of an incremental checkpoint - frame iWalFrame of the wal
** file should be copied to page iDbPage of the database file.
*/
struct OtaFrame {
  u32 iDbPage;
  u32 iWalFrame;
};

/*
** OTA handle.
................................................................................
  int nFrameAlloc;                /* Allocated size of aFrame[] array */
  OtaFrame *aFrame;
  int pgsz;
  u8 *aBuf;
  i64 iWalCksum;
};

/*
** An ota VFS is implemented using an instance of this structure.
*/
struct ota_vfs {
  sqlite3_vfs base;               /* ota VFS shim methods */
  sqlite3_vfs *pRealVfs;          /* Underlying VFS */
  sqlite3_mutex *mutex;           /* Mutex to protect pMain */
  ota_file *pMain;                /* Linked list of main db files */
};

/*
** Each file opened by an ota VFS is represented by an instance of
** the following structure.
*/
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 openFlags;                  /* Flags this file was opened with */
................................................................................

    if( rc==SQLITE_OK ){
      if( pIter->bCleanup ){
        otaObjIterFreeCols(pIter);
        pIter->bCleanup = 0;
        rc = sqlite3_step(pIter->pTblIter);
        if( rc!=SQLITE_ROW ){
          rc = resetAndCollectError(pIter->pTblIter, &p->zErrmsg);
          pIter->zTbl = 0;
        }else{
          pIter->zTbl = (const char*)sqlite3_column_text(pIter->pTblIter, 0);
          pIter->iTnum = sqlite3_column_int(pIter->pTblIter, 1);
          rc = pIter->zTbl ? SQLITE_OK : SQLITE_NOMEM;
        }
      }else{
................................................................................
        if( pIter->zIdx==0 ){
          sqlite3_stmt *pIdx = pIter->pIdxIter;
          rc = sqlite3_bind_text(pIdx, 1, pIter->zTbl, -1, SQLITE_STATIC);
        }
        if( rc==SQLITE_OK ){
          rc = sqlite3_step(pIter->pIdxIter);
          if( rc!=SQLITE_ROW ){
            rc = resetAndCollectError(pIter->pIdxIter, &p->zErrmsg);
            pIter->bCleanup = 1;
            pIter->zIdx = 0;
          }else{
            pIter->zIdx = (const char*)sqlite3_column_text(pIter->pIdxIter, 0);
            pIter->iTnum = sqlite3_column_int(pIter->pIdxIter, 1);
            pIter->bUnique = sqlite3_column_int(pIter->pIdxIter, 2);
            rc = pIter->zIdx ? SQLITE_OK : SQLITE_NOMEM;
................................................................................
    }
  }

  if( rc!=SQLITE_OK ){
    otaObjIterFinalize(pIter);
    p->rc = rc;
  }

  return rc;
}

/*
** Initialize the iterator structure passed as the second argument.
**
** If no error occurs, SQLITE_OK is returned and the iterator is left 
................................................................................
    );
  }

  pIter->bCleanup = 1;
  p->rc = rc;
  return otaObjIterNext(p, pIter);
}

/*
** This is a wrapper around "sqlite3_mprintf(zFmt, ...)". If an OOM occurs,
** an error code is stored in the OTA handle passed as the first argument.
**
** If an error has already occurred (p->rc is already set to something other
** than SQLITE_OK), then this function returns NULL without modifying the
** stored error code. In this case it still calls sqlite3_free() on any 
** printf() parameters associated with %z conversions.
*/
static char *otaMPrintf(sqlite3ota *p, const char *zFmt, ...){
  char *zSql = 0;
  va_list ap;
  va_start(ap, zFmt);
  zSql = sqlite3_vmprintf(zFmt, ap);
  if( p->rc==SQLITE_OK ){
    if( zSql==0 ) p->rc = SQLITE_NOMEM;
  }else{
    sqlite3_free(zSql);
    zSql = 0;
  }
  va_end(ap);
  return zSql;
}

/*
** Argument zFmt is a sqlite3_mprintf() style format string. The trailing
** arguments are the usual subsitution values. This function performs
** the printf() style substitutions and executes the result as an SQL
** statement on the OTA handles database.
**
................................................................................
** If an error occurs, an error code and error message is stored in the
** OTA handle. If an error has already occurred when this function is
** called, it is a no-op.
*/
static int otaMPrintfExec(sqlite3ota *p, const char *zFmt, ...){
  va_list ap;
  va_start(ap, zFmt);

  char *zSql = sqlite3_vmprintf(zFmt, ap);
  if( p->rc==SQLITE_OK ){
    if( zSql==0 ){
      p->rc = SQLITE_NOMEM;
    }else{
      p->rc = sqlite3_exec(p->db, zSql, 0, 0, &p->zErrmsg);

    }
  }
  sqlite3_free(zSql);
  va_end(ap);
  return p->rc;
}

/*
** Attempt to allocate and return a pointer to a zeroed block of nByte 
** bytes. 
**
** If an error (i.e. an OOM condition) occurs, return NULL and leave an 
** error code in the ota handle passed as the first argument. Or, if an 
** error has already occurred when this function is called, return NULL 
** immediately without attempting the allocation or modifying the stored
** error code.
*/
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{
................................................................................
    pIter->azTblType = &azNew[nCol];
    pIter->aiSrcOrder = (int*)&pIter->azTblType[nCol];
    pIter->abTblPk = (u8*)&pIter->aiSrcOrder[nCol];
    pIter->abNotNull = (u8*)&pIter->abTblPk[nCol];
  }
}

/*
** The first argument must be a nul-terminated string. This function
** returns a copy of the string in memory obtained from sqlite3_malloc().
** It is the responsibility of the caller to eventually free this memory
** using sqlite3_free().
**
** If an OOM condition is encountered when attempting to allocate memory,
** output variable (*pRc) is set to SQLITE_NOMEM before returning. Otherwise,
** if the allocation succeeds, (*pRc) is left unchanged.
*/
static char *otaStrndup(const char *zStr, int *pRc){
  char *zRet = 0;

  assert( *pRc==SQLITE_OK );
  if( zStr ){
    int nCopy = strlen(zStr) + 1;
    zRet = (char*)sqlite3_malloc(nCopy);
................................................................................
    }else{
      *pRc = SQLITE_NOMEM;
    }
  }

  return zRet;
}

/*
** Finalize the statement passed as the second argument.
**
** If the sqlite3_finalize() call indicates that an error occurs, and the
** ota handle error code is not already set, set the error code and error
** message accordingly.
*/
static void otaFinalize(sqlite3ota *p, sqlite3_stmt *pStmt){
  sqlite3 *db = sqlite3_db_handle(pStmt);
  int rc = sqlite3_finalize(pStmt);
  if( p->rc==SQLITE_OK && rc!=SQLITE_OK ){
    p->rc = rc;
    p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
  }
}

/* Determine the type of a table.
**
**   peType is of type (int*), a pointer to an output parameter of type
**   (int). This call sets the output parameter as follows, depending
**   on the type of the table specified by parameters dbName and zTbl.
**
................................................................................
    }
    *peType = OTA_PK_NONE;
  }

otaTableType_end: {
    int i;
    for(i=0; i<sizeof(aStmt)/sizeof(aStmt[0]); i++){
      otaFinalize(p, aStmt[i]);

    }
  }
}


/*
** If they are not already populated, populate the pIter->azTblCol[],
................................................................................
** the OTA handle.
*/
static int otaObjIterCacheTableInfo(sqlite3ota *p, OtaObjIter *pIter){
  if( pIter->azTblCol==0 ){
    sqlite3_stmt *pStmt = 0;
    int nCol = 0;
    int i;                        /* for() loop iterator variable */

    int bOtaRowid = 0;            /* If input table has column "ota_rowid" */
    int iOrder = 0;

    /* Figure out the type of table this step will deal with. */
    assert( pIter->eType==0 );
    otaTableType(p, pIter->zTbl, &pIter->eType, &pIter->iPkTnum);
    if( p->rc ) return p->rc;
................................................................................
        pIter->azTblType[iOrder] = otaStrndup(zType, &p->rc);
        pIter->abTblPk[iOrder] = (iPk!=0);
        pIter->abNotNull[iOrder] = (u8)bNotNull || (iPk!=0);
        iOrder++;
      }
    }

    otaFinalize(p, pStmt);

  }

  return p->rc;
}

























/*
** 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 */
................................................................................
*/
static void otaBadControlError(sqlite3ota *p){
  p->rc = SQLITE_ERROR;
  p->zErrmsg = sqlite3_mprintf("invalid ota_control value");
}


/*
** Return a nul-terminated string containing the comma separated list of
** assignments that should be included following the "SET" keyword of
** an UPDATE statement used to update the table object that the iterator
** passed as the second argument currently points to if the ota_control
** column of the data_xxx table entry is set to zMask.
**
** The memory for the returned string is obtained from sqlite3_malloc().
** It is the responsibility of the caller to eventually free it using
** sqlite3_free(). 
**
** If an OOM error is encountered when allocating space for the new
** string, an error code is left in the ota handle passed as the first
** argument and NULL is returned. Or, if an error has already occurred
** when this function is called, NULL is returned immediately, without
** attempting the allocation or modifying the stored error code.
*/
static char *otaObjIterGetSetlist(
  sqlite3ota *p,
  OtaObjIter *pIter,
  const char *zMask
){
  char *zList = 0;
  if( p->rc==SQLITE_OK ){
................................................................................
        }
      }
    }
  }
  return zList;
}

/*
** Return a nul-terminated string consisting of nByte comma separated
** "?" expressions. For example, if nByte is 3, return a pointer to
** a buffer containing the string "?,?,?".
**
** The memory for the returned string is obtained from sqlite3_malloc().
** It is the responsibility of the caller to eventually free it using
** sqlite3_free(). 
**
** If an OOM error is encountered when allocating space for the new
** string, an error code is left in the ota handle passed as the first
** argument and NULL is returned. Or, if an error has already occurred
** when this function is called, NULL is returned immediately, without
** attempting the allocation or modifying the stored error code.
*/
static char *otaObjIterGetBindlist(sqlite3ota *p, int nBind){
  char *zRet = 0;
  int nByte = nBind*2 + 1;

  zRet = (char*)otaMalloc(p, nByte);
  if( zRet ){
    int i;
................................................................................
static char *otaWithoutRowidPK(sqlite3ota *p, OtaObjIter *pIter){
  char *z = 0;
  assert( pIter->zIdx==0 );
  if( p->rc==SQLITE_OK ){
    const char *zSep = "PRIMARY KEY(";
    sqlite3_stmt *pXList = 0;     /* PRAGMA index_list = (pIter->zTbl) */
    sqlite3_stmt *pXInfo = 0;     /* PRAGMA index_xinfo = <pk-index> */


   
    p->rc = prepareFreeAndCollectError(p->db, &pXList, &p->zErrmsg,
        sqlite3_mprintf("PRAGMA main.index_list = %Q", pIter->zTbl)
    );
    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXList) ){
      const char *zOrig = (const char*)sqlite3_column_text(pXList,3);
      if( zOrig && strcmp(zOrig, "pk")==0 ){
................................................................................
          p->rc = prepareFreeAndCollectError(p->db, &pXInfo, &p->zErrmsg,
              sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", zIdx)
          );
        }
        break;
      }
    }
    otaFinalize(p, pXList);


    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      if( sqlite3_column_int(pXInfo, 5) ){
        /* int iCid = sqlite3_column_int(pXInfo, 0); */
        const char *zCol = (const char*)sqlite3_column_text(pXInfo, 2);
        const char *zDesc = sqlite3_column_int(pXInfo, 3) ? " DESC" : "";
        z = otaMPrintf(p, "%z%s\"%w\"%s", z, zSep, zCol, zDesc);
        zSep = ", ";
      }
    }
    z = otaMPrintf(p, "%z)", z);
    otaFinalize(p, pXInfo);

  }
  return z;
}






/*
** This function creates the second imposter table used when writing to
** a table b-tree where the table has an external primary key. If the
** iterator passed as the second argument does not currently point to
** a table (not index) with an external primary key, this function is a
** no-op. 
**
................................................................................
*/
static void otaCreateImposterTable2(sqlite3ota *p, OtaObjIter *pIter){
  if( p->rc==SQLITE_OK && pIter->eType==OTA_PK_EXTERNAL ){
    int tnum = pIter->iPkTnum;    /* Root page of PK index */
    sqlite3_stmt *pQuery = 0;     /* SELECT name ... WHERE rootpage = $tnum */
    const char *zIdx = 0;         /* Name of PK index */
    sqlite3_stmt *pXInfo = 0;     /* PRAGMA main.index_xinfo = $zIdx */


    const char *zComma = "";

    char *zCols = 0;              /* Used to build up list of table cols */
    char *zPk = 0;                /* Used to build up table PK declaration */


    /* Figure out the name of the primary key index for the current table.
    ** This is needed for the argument to "PRAGMA index_xinfo". Set
    ** zIdx to point to a nul-terminated string containing this name. */
    p->rc = prepareAndCollectError(p->db, &pQuery, &p->zErrmsg, 
        "SELECT name FROM sqlite_master WHERE rootpage = ?"
    );
................................................................................
            iCid, pIter->azTblType[iCid], zCollate
        );
        zPk = otaMPrintf(p, "%z%sc%d%s", zPk, zComma, iCid, bDesc?" DESC":"");
        zComma = ", ";
      }
    }
    zCols = otaMPrintf(p, "%z, id INTEGER", zCols);
    otaFinalize(p, pXInfo);


    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->db, "main", 1, tnum);
    otaMPrintfExec(p, 
        "CREATE TABLE ota_imposter2(%z, PRIMARY KEY(%z)) WITHOUT ROWID", 
        zCols, zPk
    );




    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->db, "main", 0, 0);


  }
}

/*
** If an error has already occurred when this function is called, it 
** immediately returns zero (without doing any work). Or, if an error
** occurs during the execution of this function, it sets the error code
** in the sqlite3ota object indicated by the first argument and returns
** zero.
**
** The iterator passed as the second argument is guaranteed to point to
** a table (not an index) when this function is called. This function
** attempts to create any imposter table required to write to the main
** table b-tree of the table before returning. Non-zero is returned if
** an imposter table are created, or zero otherwise.
**




** An imposter table is required in all cases except OTA_PK_VTAB. Only
** virtual tables are written to directly. The imposter table has the 
** same schema as the actual target table (less any UNIQUE constraints). 
** More precisely, the "same schema" means the same columns, types, 









** collation sequences. For tables that do not have an external PRIMARY
** KEY, it also means the same PRIMARY KEY declaration.
*/
static void otaCreateImposterTable(sqlite3ota *p, OtaObjIter *pIter){
  if( p->rc==SQLITE_OK && pIter->eType!=OTA_PK_VTAB ){
    int tnum = pIter->iTnum;
    const char *zComma = "";
    char *zSql = 0;
    int iCol;
................................................................................
    if( pIter->eType==OTA_PK_WITHOUT_ROWID ){
      char *zPk = otaWithoutRowidPK(p, pIter);
      if( zPk ){
        zSql = otaMPrintf(p, "%z, %z", zSql, zPk);
      }
    }

    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->db, "main", 1, tnum);
    otaMPrintfExec(p, "CREATE TABLE \"ota_imp_%w\"(%z)%s", 
        pIter->zTbl, zSql, 
        (pIter->eType==OTA_PK_WITHOUT_ROWID ? " WITHOUT ROWID" : "")
    );



    sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, p->db, "main", 0, 0);


  }
}

/*
** Ensure that the SQLite statement handles required to update the 
** target database object currently indicated by the iterator passed 
** as the second argument are available.
................................................................................
    sqlite3_free(zCollist);
    sqlite3_free(zLimit);
  }
  
  return p->rc;
}


/*
** Set output variable *ppStmt to point to an UPDATE statement that may
** be used to update the imposter table for the main table b-tree of the
** table object that pIter currently points to, assuming that the 
** ota_control column of the data_xyz table contains zMask.

*/
static int otaGetUpdateStmt(
  sqlite3ota *p,                  /* OTA handle */
  OtaObjIter *pIter,              /* Object iterator */
  const char *zMask,              /* ota_control value ('x.x.') */
  sqlite3_stmt **ppStmt           /* OUT: UPDATE statement handle */
){
  if( pIter->pUpdate && strcmp(zMask, pIter->zMask)==0 ){
    *ppStmt = pIter->pUpdate;
  }else{
    char *zWhere = otaObjIterGetWhere(p, pIter);
    char *zSet = otaObjIterGetSetlist(p, pIter, zMask);
    char *zUpdate = 0;
................................................................................
      ** is already a transaction open, so the prepared statement cannot
      ** throw an SQLITE_SCHEMA exception. The only database page the
      ** statement reads is page 1, which is guaranteed to be in the cache.
      ** And no memory allocations are required.  */
      if( SQLITE_ROW==sqlite3_step(pStmt) ){
        iCookie = sqlite3_column_int(pStmt, 0);
      }
      otaFinalize(p, pStmt);
    }
    if( p->rc==SQLITE_OK ){
      otaMPrintfExec(p, "PRAGMA schema_version = %d", iCookie+1);
    }
  }
}

................................................................................
          OTA_STATE_TBL, p->objiter.zTbl, 
          OTA_STATE_IDX, p->objiter.zIdx, 
          OTA_STATE_ROW, p->nStep, 
          OTA_STATE_PROGRESS, p->nProgress,
          OTA_STATE_CKPT, p->iWalCksum,
          OTA_STATE_COOKIE, (i64)p->pTargetFd->iCookie
          )
    );
    assert( pInsert==0 || rc==SQLITE_OK );

    if( rc==SQLITE_OK ){
      sqlite3_step(pInsert);
      rc = sqlite3_finalize(pInsert);


    }

    if( rc!=SQLITE_OK ) p->rc = rc;


  }
}


/*
** Step the OTA object.
*/
................................................................................
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 && pVfs->xOpen==otaVfsOpen ){
    sqlite3_mutex_free(((ota_vfs*)pVfs)->mutex);
    sqlite3_vfs_unregister(pVfs);
    sqlite3_free(pVfs);
  }
}

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

................................................................................
      rc = SQLITE_NOTFOUND;
    }else{
      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);

      /* Allocate the mutex and register the new VFS (not as the default) */
      pNew->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_RECURSIVE);
      if( pNew->mutex==0 ){
        rc = SQLITE_NOMEM;
      }else{
        rc = sqlite3_vfs_register(&pNew->base, 0);
      }
    }

    if( rc!=SQLITE_OK ){
      sqlite3_mutex_free(pNew->mutex);
      sqlite3_free(pNew);
    }
  }




  return rc;
}


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

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_OTA) */