SQLite

# 2016 April 15
#
# 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 the RBU module. More specifically, it
# contains tests to ensure that the sqlite3rbu_vacuum() API works as
# expected.
#

source [file join [file dirname [info script]] rbu_common.tcl]
set ::testprefix rbuvacuum

proc do_rbu_vacuum_test {tn} {
  uplevel [list do_test $tn.1 {
    forcedelete state.db
    if {$::step==0} { sqlite3rbu_vacuum rbu test.db state.db }
    while 1 {
      if {$::step==1} { sqlite3rbu_vacuum rbu test.db state.db }
      set rc [rbu step]
      if {$rc!="SQLITE_OK"} break
      if {$::step==1} { rbu close }
    }
    rbu close
  } {SQLITE_DONE}]

  uplevel [list do_execsql_test $tn.2 {
    PRAGMA integrity_check
  } ok]
}

foreach step {0 1} {

  set ::testprefix rbuvacuum-step=$step
  reset_db

  # Simplest possible vacuum.
  do_execsql_test 1.0 {
    PRAGMA page_size = 1024;
    CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c);
    INSERT INTO t1 VALUES(1, 2, 3);
    INSERT INTO t1 VALUES(4, 5, 6);
    INSERT INTO t1 VALUES(7, 8, 9);
    PRAGMA integrity_check;
  } {ok}
  do_rbu_vacuum_test 1.1

  # A vacuum that actually reclaims space.
  do_execsql_test 1.2.1 {
    INSERT INTO t1 VALUES(8, randomblob(900), randomblob(900));
    INSERT INTO t1 VALUES(9, randomblob(900), randomblob(900));
    INSERT INTO t1 VALUES(10, randomblob(900), randomblob(900));
    INSERT INTO t1 VALUES(11, randomblob(900), randomblob(900));
    INSERT INTO t1 VALUES(12, randomblob(900), randomblob(900));
    PRAGMA page_count;
  } {12}
  do_execsql_test 1.2.2 {
    DELETE FROM t1 WHERE rowid BETWEEN 8 AND 11;
    PRAGMA page_count;
  } {12}
  do_rbu_vacuum_test 1.2.3
  do_execsql_test 1.2.4 {
    PRAGMA page_count;
  } {3}
  
  # Add an index to the table.
  do_execsql_test 1.3.1 {
    CREATE INDEX t1b ON t1(b);
    INSERT INTO t1 VALUES(13, randomblob(900), randomblob(900));
    INSERT INTO t1 VALUES(14, randomblob(900), randomblob(900));
    INSERT INTO t1 VALUES(15, randomblob(900), randomblob(900));
    INSERT INTO t1 VALUES(16, randomblob(900), randomblob(900));
    PRAGMA page_count;
  } {18}
  do_execsql_test 1.3.2 {
    DELETE FROM t1 WHERE rowid BETWEEN 12 AND 15;
    PRAGMA page_count;
  } {18}
  do_rbu_vacuum_test 1.3.3
  do_execsql_test 1.3.4 {
    PRAGMA page_count;
  } {5}

  # WITHOUT ROWID table.
  do_execsql_test 1.4.1 {
    CREATE TABLE t2(a, b, c, PRIMARY KEY(a, b)) WITHOUT ROWID;

    INSERT INTO t2 VALUES(randomblob(900), 1, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 2, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 3, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 4, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 6, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 7, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 8, randomblob(900));

    DELETE FROM t2 WHERE b BETWEEN 2 AND 7;
    PRAGMA page_count;
  } {20}
  do_rbu_vacuum_test 1.4.2
  do_execsql_test 1.4.3 {
    PRAGMA page_count;
  } {10}
  
  # WITHOUT ROWID table with an index.
  do_execsql_test 1.4.1 {
    CREATE INDEX t2c ON t2(c);

    INSERT INTO t2 VALUES(randomblob(900), 9, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 10, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 11, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 12, randomblob(900));
    INSERT INTO t2 VALUES(randomblob(900), 13, randomblob(900));

    DELETE FROM t2 WHERE b BETWEEN 8 AND 12;
    PRAGMA page_count;
  } {35}
  do_rbu_vacuum_test 1.4.2
  do_execsql_test 1.4.3 {
    PRAGMA page_count;
  } {15}
  do_execsql_test 1.4.4 {
    VACUUM;
    PRAGMA page_count;
  } {15}

  do_execsql_test 1.5.1 {
    CREATE TABLE t3(a, b, c);
    INSERT INTO t3 VALUES('a', 'b', 'c');
    INSERT INTO t3 VALUES('d', 'e', 'f');
    INSERT INTO t3 VALUES('g', 'h', 'i');
  }
  do_rbu_vacuum_test 1.5.2
  do_execsql_test 1.5.3 {
    SELECT * FROM t3
  } {a b c d e f g h i}
  do_execsql_test 1.5.4 {
    CREATE INDEX t3a ON t3(a);
    CREATE INDEX t3b ON t3(b);
    CREATE INDEX t3c ON t3(c);
    INSERT INTO t3 VALUES('j', 'k', 'l');
    DELETE FROM t3 WHERE a = 'g';
  }
  do_rbu_vacuum_test 1.5.5
  do_execsql_test 1.5.6 {
    SELECT rowid, * FROM t3 ORDER BY b
  } {1 a b c 2 d e f 4 j k l}

  do_execsql_test 1.6.1 {
    CREATE TABLE t4(a PRIMARY KEY, b, c);
    INSERT INTO t4 VALUES('a', 'b', 'c');
    INSERT INTO t4 VALUES('d', 'e', 'f');
    INSERT INTO t4 VALUES('g', 'h', 'i');
  }
  do_rbu_vacuum_test 1.6.2
  do_execsql_test 1.6.3 {
    SELECT * FROM t4
  } {a b c d e f g h i}
  do_execsql_test 1.6.4 {
    CREATE INDEX t4a ON t4(a);
    CREATE INDEX t4b ON t4(b);
    CREATE INDEX t4c ON t4(c);
    
    INSERT INTO t4 VALUES('j', 'k', 'l');
    DELETE FROM t4 WHERE a='g';
  }
  do_rbu_vacuum_test 1.6.5
  do_execsql_test 1.6.6 {
    SELECT * FROM t4 ORDER BY b
  } {a b c d e f j k l}

}

catch { db close }
finish_test

typedef struct RbuState RbuState;
typedef struct rbu_vfs rbu_vfs;
typedef struct rbu_file rbu_file;
typedef struct RbuUpdateStmt RbuUpdateStmt;

#if !defined(SQLITE_AMALGAMATION)
typedef unsigned int u32;
typedef unsigned short u16;
typedef unsigned char u8;
typedef sqlite3_int64 i64;
#endif

/*
** These values must match the values defined in wal.c for the equivalent
** locks. These are not magic numbers as they are part of the SQLite file

  char *zDel;                     /* Delete this when closing file */

  const char *zWal;               /* Wal filename for this main db file */
  rbu_file *pWalFd;               /* Wal file descriptor for this main db */
  rbu_file *pMainNext;            /* Next MAIN_DB file */
};

/*
** True for an RBU vacuum handle, or false otherwise.
*/
#define rbuIsVacuum(p) ((p)->zTarget==0)


/*************************************************************************
** The following three functions, found below:
**
**   rbuDeltaGetInt()
**   rbuDeltaChecksum()
**   rbuDeltaApply()

  }
  return rc;
}


/*
** The implementation of the rbu_target_name() SQL function. This function
** accepts one or two arguments. The first argument is the name of a table -
** the name of a table in the RBU database.  The second, if it is present, is 1
** for a view or 0 for a table. 
**
** For a non-vacuum RBU handle, if the table name matches the pattern:
**
**     data[0-9]_<name>
**
** where <name> is any sequence of 1 or more characters, <name> is returned.
** Otherwise, if the only argument does not match the above pattern, an SQL
** NULL is returned.
**
**     "data_t1"     -> "t1"
**     "data0123_t2" -> "t2"
**     "dataAB_t3"   -> NULL
**
** For an rbu vacuum handle, a copy of the first argument is returned if
** the second argument is either missing or 0 (not a view).
*/
static void rbuTargetNameFunc(
  sqlite3_context *pCtx,
  int argc,
  sqlite3_value **argv
){
  sqlite3rbu *p = sqlite3_user_data(pCtx);
  const char *zIn;
  assert( argc==1 || argc==2 );

  zIn = (const char*)sqlite3_value_text(argv[0]);
  if( zIn ){
    if( rbuIsVacuum(p) ){
      if( argc==1 || 0==sqlite3_value_int(argv[1]) ){
        sqlite3_result_text(pCtx, zIn, -1, SQLITE_STATIC);
      }
    }else{
      if( strlen(zIn)>4 && memcmp("data", zIn, 4)==0 ){
        int i;
        for(i=4; zIn[i]>='0' && zIn[i]<='9'; i++);
        if( zIn[i]=='_' && zIn[i+1] ){
          sqlite3_result_text(pCtx, &zIn[i+1], -1, SQLITE_STATIC);
        }
      }
    }
  }
}

/*
** Initialize the iterator structure passed as the second argument.
**
** If no error occurs, SQLITE_OK is returned and the iterator is left 
** pointing to the first entry. Otherwise, an error code and message is 
** left in the RBU handle passed as the first argument. A copy of the 
** error code is returned.
*/
static int rbuObjIterFirst(sqlite3rbu *p, RbuObjIter *pIter){
  int rc;
  memset(pIter, 0, sizeof(RbuObjIter));

  rc = prepareAndCollectError(p->dbRbu, &pIter->pTblIter, &p->zErrmsg, 
      "SELECT rbu_target_name(name, type='view') AS target, name "
      "FROM sqlite_master "
      "WHERE type IN ('table', 'view') AND target IS NOT NULL "
      "ORDER BY name"
  );

  if( rc==SQLITE_OK ){
    rc = prepareAndCollectError(p->dbMain, &pIter->pIdxIter, &p->zErrmsg,
        "SELECT name, rootpage, sql IS NULL OR substr(8, 6)=='UNIQUE' "

        bRbuRowid = 1;
      }
    }
    sqlite3_finalize(pStmt);
    pStmt = 0;

    if( p->rc==SQLITE_OK
     && rbuIsVacuum(p)==0
     && bRbuRowid!=(pIter->eType==RBU_PK_VTAB || pIter->eType==RBU_PK_NONE)
    ){
      p->rc = SQLITE_ERROR;
      p->zErrmsg = sqlite3_mprintf(
          "table %q %s rbu_rowid column", pIter->zDataTbl,
          (bRbuRowid ? "may not have" : "requires")
      );

      /* An integer primary key. If the table has an explicit IPK, use
      ** its name. Otherwise, use "rbu_rowid".  */
      if( pIter->eType==RBU_PK_IPK ){
        int i;
        for(i=0; pIter->abTblPk[i]==0; i++);
        assert( i<pIter->nTblCol );
        zCol = pIter->azTblCol[i];
      }else if( rbuIsVacuum(p) ){
        zCol = "_rowid_";
      }else{
        zCol = "rbu_rowid";
      }
      zType = "INTEGER";
    }else{
      zCol = pIter->azTblCol[iCid];
      zType = pIter->azTblType[iCid];

        p->rc = prepareFreeAndCollectError(
            p->dbMain, &pIter->pInsert, &p->zErrmsg,
          sqlite3_mprintf("INSERT INTO \"rbu_imp_%w\" VALUES(%s)", zTbl, zBind)
        );
      }

      /* And to delete index entries */
      if( rbuIsVacuum(p)==0 && p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(
            p->dbMain, &pIter->pDelete, &p->zErrmsg,
          sqlite3_mprintf("DELETE FROM \"rbu_imp_%w\" WHERE %s", zTbl, zWhere)
        );
      }

      /* Create the SELECT statement to read keys in sorted order */
      if( p->rc==SQLITE_OK ){
        char *zSql;
        if( rbuIsVacuum(p) ){
          zSql = sqlite3_mprintf(
              "SELECT %s, 0 AS rbu_control FROM '%q' ORDER BY %s%s",
              zCollist, 
              pIter->zDataTbl,
              zCollist, zLimit
          );
        }else

        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
          zSql = sqlite3_mprintf(
              "SELECT %s, rbu_control FROM %s.'rbu_tmp_%q' ORDER BY %s%s",
              zCollist, p->zStateDb, pIter->zDataTbl,
              zCollist, zLimit
          );
        }else{

      }

      sqlite3_free(zImposterCols);
      sqlite3_free(zImposterPK);
      sqlite3_free(zWhere);
      sqlite3_free(zBind);
    }else{
      int bRbuRowid = (pIter->eType==RBU_PK_VTAB)
                    ||(pIter->eType==RBU_PK_NONE)
                    ||(pIter->eType==RBU_PK_EXTERNAL && rbuIsVacuum(p));
      const char *zTbl = pIter->zTbl;       /* Table this step applies to */
      const char *zWrite;                   /* Imposter table name */

      char *zBindings = rbuObjIterGetBindlist(p, pIter->nTblCol + bRbuRowid);
      char *zWhere = rbuObjIterGetWhere(p, pIter);
      char *zOldlist = rbuObjIterGetOldlist(p, pIter, "old");
      char *zNewlist = rbuObjIterGetOldlist(p, pIter, "new");

            sqlite3_mprintf(
              "INSERT INTO \"%s%w\"(%s%s) VALUES(%s)", 
              zWrite, zTbl, zCollist, (bRbuRowid ? ", _rowid_" : ""), zBindings
            )
        );
      }

      /* Create the DELETE statement to write to the target PK b-tree.
      ** Because it only performs INSERT operations, this is not required for
      ** an rbu vacuum handle.  */
      if( rbuIsVacuum(p)==0 && p->rc==SQLITE_OK ){
        p->rc = prepareFreeAndCollectError(p->dbMain, &pIter->pDelete, pz,
            sqlite3_mprintf(
              "DELETE FROM \"%s%w\" WHERE %s", zWrite, zTbl, zWhere
            )
        );
      }

      if( rbuIsVacuum(p)==0 && pIter->abIndexed ){
        const char *zRbuRowid = "";
        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
          zRbuRowid = ", rbu_rowid";
        }

        /* Create the rbu_tmp_xxx table and the triggers to populate it. */
        rbuMPrintfExec(p, p->dbRbu,

        }

        rbuObjIterPrepareTmpInsert(p, pIter, zCollist, zRbuRowid);
      }

      /* Create the SELECT statement to read keys from data_xxx */
      if( p->rc==SQLITE_OK ){
        const char *zRbuRowid = "";
        if( bRbuRowid ){
          zRbuRowid = rbuIsVacuum(p) ? ",_rowid_ " : ",rbu_rowid";
        }
        p->rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pSelect, pz,
            sqlite3_mprintf(
              "SELECT %s,%s rbu_control%s FROM '%q'%s", 
              zCollist, 
              (rbuIsVacuum(p) ? "0 AS " : ""),
              zRbuRowid,
              pIter->zDataTbl, zLimit
            )
        );
      }

      sqlite3_free(zWhere);
      sqlite3_free(zOldlist);

      p->zErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
      sqlite3_close(db);
      db = 0;
    }
  }
  return db;
}

/*
** Free an RbuState object allocated by rbuLoadState().
*/
static void rbuFreeState(RbuState *p){
  if( p ){
    sqlite3_free(p->zTbl);
    sqlite3_free(p->zIdx);
    sqlite3_free(p);
  }
}

/*
** Allocate an RbuState object and load the contents of the rbu_state 
** table into it. Return a pointer to the new object. It is the 
** responsibility of the caller to eventually free the object using
** sqlite3_free().
**
** If an error occurs, leave an error code and message in the rbu handle
** and return NULL.
*/
static RbuState *rbuLoadState(sqlite3rbu *p){
  RbuState *pRet = 0;
  sqlite3_stmt *pStmt = 0;
  int rc;
  int rc2;

  pRet = (RbuState*)rbuMalloc(p, sizeof(RbuState));
  if( pRet==0 ) return 0;

  rc = prepareFreeAndCollectError(p->dbRbu, &pStmt, &p->zErrmsg, 
      sqlite3_mprintf("SELECT k, v FROM %s.rbu_state", p->zStateDb)
  );
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
    switch( sqlite3_column_int(pStmt, 0) ){
      case RBU_STATE_STAGE:
        pRet->eStage = sqlite3_column_int(pStmt, 1);
        if( pRet->eStage!=RBU_STAGE_OAL
         && pRet->eStage!=RBU_STAGE_MOVE
         && pRet->eStage!=RBU_STAGE_CKPT
        ){
          p->rc = SQLITE_CORRUPT;
        }
        break;

      case RBU_STATE_TBL:
        pRet->zTbl = rbuStrndup((char*)sqlite3_column_text(pStmt, 1), &rc);
        break;

      case RBU_STATE_IDX:
        pRet->zIdx = rbuStrndup((char*)sqlite3_column_text(pStmt, 1), &rc);
        break;

      case RBU_STATE_ROW:
        pRet->nRow = sqlite3_column_int(pStmt, 1);
        break;

      case RBU_STATE_PROGRESS:
        pRet->nProgress = sqlite3_column_int64(pStmt, 1);
        break;

      case RBU_STATE_CKPT:
        pRet->iWalCksum = sqlite3_column_int64(pStmt, 1);
        break;

      case RBU_STATE_COOKIE:
        pRet->iCookie = (u32)sqlite3_column_int64(pStmt, 1);
        break;

      case RBU_STATE_OALSZ:
        pRet->iOalSz = (u32)sqlite3_column_int64(pStmt, 1);
        break;

      case RBU_STATE_PHASEONESTEP:
        pRet->nPhaseOneStep = sqlite3_column_int64(pStmt, 1);
        break;

      default:
        rc = SQLITE_CORRUPT;
        break;
    }
  }
  rc2 = sqlite3_finalize(pStmt);
  if( rc==SQLITE_OK ) rc = rc2;

  p->rc = rc;
  return pRet;
}


/*
** Open the database handle and attach the RBU database as "rbu". If an
** error occurs, leave an error code and message in the RBU handle.
*/
static void rbuOpenDatabase(sqlite3rbu *p){
  assert( p->rc==SQLITE_OK );
  assert( p->dbMain==0 && p->dbRbu==0 );


  /* Open the RBU database */
  p->dbRbu = rbuOpenDbhandle(p, p->zRbu);

  /* If using separate RBU and state databases, attach the state database to
  ** the RBU db handle now.  */
  if( p->zState ){
    rbuMPrintfExec(p, p->dbRbu, "ATTACH %Q AS stat", p->zState);
    memcpy(p->zStateDb, "stat", 4);
  }else{
    memcpy(p->zStateDb, "main", 4);
  }

  /* If it has not already been created, create the rbu_state table */
  rbuMPrintfExec(p, p->dbRbu, RBU_CREATE_STATE, p->zStateDb);

  if( rbuIsVacuum(p) ){
    int bOpen = 0;
    if( p->eStage>=RBU_STAGE_MOVE ){
      bOpen = 1;
    }else{
      RbuState *pState = rbuLoadState(p);
      if( pState ){
        bOpen = (pState->eStage>RBU_STAGE_MOVE);
        rbuFreeState(pState);
      }
    }
    if( bOpen ) p->dbMain = rbuOpenDbhandle(p, p->zRbu);
  }

  p->eStage = 0;
  if( p->dbMain==0 ){
    if( p->zTarget ){
      p->dbMain = rbuOpenDbhandle(p, p->zTarget);
    }else{
      char *zTarget = sqlite3_mprintf("%s-vacuum", p->zRbu);
      if( zTarget==0 ){
        p->rc = SQLITE_NOMEM;
        return;
      }
      p->dbMain = rbuOpenDbhandle(p, zTarget);
      sqlite3_free(zTarget);
    }
  }

  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_create_function(p->dbMain, 
        "rbu_tmp_insert", -1, SQLITE_UTF8, (void*)p, rbuTmpInsertFunc, 0, 0
    );
  }

  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_create_function(p->dbMain, 
        "rbu_fossil_delta", 2, SQLITE_UTF8, 0, rbuFossilDeltaFunc, 0, 0
    );
  }

  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_create_function(p->dbRbu, 
        "rbu_target_name", -1, SQLITE_UTF8, (void*)p, rbuTargetNameFunc, 0, 0
    );
  }

  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3_file_control(p->dbMain, "main", SQLITE_FCNTL_RBU, (void*)p);
  }
  rbuMPrintfExec(p, p->dbMain, "SELECT * FROM sqlite_master");

** on the database file. This proc moves the *-oal file to the *-wal path,
** then reopens the database file (this time in vanilla, non-oal, WAL mode).
** If an error occurs, leave an error code and error message in the rbu 
** handle.
*/
static void rbuMoveOalFile(sqlite3rbu *p){
  const char *zBase = sqlite3_db_filename(p->dbMain, "main");
  char *zOal = sqlite3_mprintf("%s-oal", zBase);
  char *zWal;

  if( rbuIsVacuum(p) ){
    zWal = sqlite3_mprintf("%s-wal", sqlite3_db_filename(p->dbRbu, "main"));
  }else{
    zWal = sqlite3_mprintf("%s-wal", zBase);
  }

  assert( p->eStage==RBU_STAGE_MOVE );
  assert( p->rc==SQLITE_OK && p->zErrmsg==0 );
  if( zWal==0 || zOal==0 ){
    p->rc = SQLITE_NOMEM;
  }else{
    /* Move the *-oal file to *-wal. At this point connection p->db is
    ** holding a SHARED lock on the target database file (because it is
    ** in WAL mode). So no other connection may be writing the db. 
    **
    ** In order to ensure that there are no database readers, an EXCLUSIVE
    ** lock is obtained here before the *-oal is moved to *-wal.
    */
    rbuLockDatabase(p);
    if( p->rc==SQLITE_OK ){
      rbuFileSuffix3(zBase, zWal);
      rbuFileSuffix3(zBase, zOal);

      /* Re-open the databases. */
      rbuObjIterFinalize(&p->objiter);
      sqlite3_close(p->dbRbu);
      sqlite3_close(p->dbMain);
      p->dbMain = 0;
      p->dbRbu = 0;

#if defined(_WIN32_WCE)
      {
        LPWSTR zWideOal;
        LPWSTR zWideWal;

      continue;
    }

    pVal = sqlite3_column_value(pIter->pSelect, i);
    p->rc = sqlite3_bind_value(pWriter, i+1, pVal);
    if( p->rc ) return;
  }
  if( pIter->zIdx==0 ){
    if( pIter->eType==RBU_PK_VTAB 
     || pIter->eType==RBU_PK_NONE 
     || (pIter->eType==RBU_PK_EXTERNAL && rbuIsVacuum(p)) 
    ){
      /* For a virtual table, or a table with no primary key, the 
      ** SELECT statement is:
      **
      **   SELECT <cols>, rbu_control, rbu_rowid FROM ....
      **
      ** Hence column_value(pIter->nCol+1).
      */
      assertColumnName(pIter->pSelect, pIter->nCol+1, 
          rbuIsVacuum(p) ? "rowid" : "rbu_rowid"
      );
      pVal = sqlite3_column_value(pIter->pSelect, pIter->nCol+1);
      p->rc = sqlite3_bind_value(pWriter, pIter->nCol+1, pVal);
    }
  }
  if( p->rc==SQLITE_OK ){
    sqlite3_step(pWriter);
    p->rc = resetAndCollectError(pWriter, &p->zErrmsg);
  }
}

        RbuObjIter *pIter = &p->objiter;
        while( p->rc==SQLITE_OK && pIter->zTbl ){

          if( pIter->bCleanup ){
            /* Clean up the rbu_tmp_xxx table for the previous table. It 
            ** cannot be dropped as there are currently active SQL statements.
            ** But the contents can be deleted.  */
            if( rbuIsVacuum(p)==0 && pIter->abIndexed ){
              rbuMPrintfExec(p, p->dbRbu, 
                  "DELETE FROM %s.'rbu_tmp_%q'", p->zStateDb, pIter->zDataTbl
              );
            }
          }else{
            rbuObjIterPrepareAll(p, pIter, 0);

    }
    return p->rc;
  }else{
    return SQLITE_NOMEM;
  }
}

























































































/*
** Compare strings z1 and z2, returning 0 if they are identical, or non-zero
** otherwise. Either or both argument may be NULL. Two NULL values are
** considered equal, and NULL is considered distinct from all other values.
*/
static int rbuStrCompare(const char *z1, const char *z2){
  if( z1==0 && z2==0 ) return 0;

        p->rc = sqlite3_finalize(pStmt);
      }
    }
  }
}

/*
** The RBU handle passed as the only argument has just been opened and 
** the state database is empty. If this RBU handle was opened for an
** RBU vacuum operation, create the schema in the target db.
*/
static void rbuCreateTargetSchema(sqlite3rbu *p){
  sqlite3_stmt *pSql = 0;
  sqlite3_stmt *pInsert = 0;
  int rc2;

  assert( rbuIsVacuum(p) );

  p->rc = prepareAndCollectError(p->dbRbu, &pSql, &p->zErrmsg, 
    "SELECT sql FROM sqlite_master WHERE sql!='' AND rootpage!=0"
    " ORDER BY type DESC"
  );
  while( p->rc==SQLITE_OK && sqlite3_step(pSql)==SQLITE_ROW ){
    const char *zSql = sqlite3_column_text(pSql, 0);
    p->rc = sqlite3_exec(p->dbMain, zSql, 0, 0, &p->zErrmsg);
  }
  rbuFinalize(p, pSql);
  if( p->rc!=SQLITE_OK ) return;

  p->rc = sqlite3_exec(p->dbMain, "PRAGMA writable_schema=1", 0,0, &p->zErrmsg);

  if( p->rc==SQLITE_OK ){
    p->rc = prepareAndCollectError(p->dbRbu, &pSql, &p->zErrmsg, 
        "SELECT * FROM sqlite_master WHERE rootpage=0 OR rootpage IS NULL" 
    );
  }

  if( p->rc==SQLITE_OK ){
    p->rc = prepareAndCollectError(p->dbMain, &pInsert, &p->zErrmsg, 
        "INSERT INTO sqlite_master VALUES(?,?,?,?,?)"
    );
  }

  while( p->rc==SQLITE_OK && sqlite3_step(pSql)==SQLITE_ROW ){
    int i;
    for(i=0; i<5; i++){
      sqlite3_bind_value(pInsert, i+1, sqlite3_column_value(pSql, i));
    }
    sqlite3_step(pInsert);
    p->rc = sqlite3_reset(pInsert);
  }

  rbuFinalize(p, pSql);
  rbuFinalize(p, pInsert);
}


static sqlite3rbu *openRbuHandle(
  const char *zTarget, 
  const char *zRbu,
  const char *zState
){
  sqlite3rbu *p;
  size_t nTarget = zTarget ? strlen(zTarget) : 0;
  size_t nRbu = strlen(zRbu);
  size_t nState = zState ? strlen(zState) : 0;
  size_t nByte = sizeof(sqlite3rbu) + nTarget+1 + nRbu+1+ nState+1;

  p = (sqlite3rbu*)sqlite3_malloc64(nByte);
  if( p ){
    RbuState *pState = 0;

    /* Create the custom VFS. */
    memset(p, 0, sizeof(sqlite3rbu));
    rbuCreateVfs(p);

    /* Open the target, RBU and state databases */
    if( p->rc==SQLITE_OK ){
      char *pCsr = (char*)&p[1];
      if( zTarget ){
        p->zTarget = pCsr;
        memcpy(p->zTarget, zTarget, nTarget+1);
        pCsr += nTarget+1;
      }
      p->zRbu = pCsr;
      memcpy(p->zRbu, zRbu, nRbu+1);
      pCsr += nRbu+1;
      if( zState ){
        p->zState = pCsr;
        memcpy(p->zState, zState, nState+1);
      }
      rbuOpenDatabase(p);
    }




    if( p->rc==SQLITE_OK ){
      pState = rbuLoadState(p);
      assert( pState || p->rc!=SQLITE_OK );
      if( p->rc==SQLITE_OK ){

        if( pState->eStage==0 ){ 
          rbuDeleteOalFile(p);

        ** generating a large journal using a temp file.  */
        if( p->rc==SQLITE_OK ){
          int frc = sqlite3_file_control(db, "main", SQLITE_FCNTL_ZIPVFS, 0);
          if( frc==SQLITE_OK ){
            p->rc = sqlite3_exec(db, "PRAGMA journal_mode=off",0,0,&p->zErrmsg);
          }
        }

        /* If this is an RBU vacuum operation and the state table was empty
        ** when this handle was opened, create the target database schema. */
        if( pState->eStage==0 && rbuIsVacuum(p) ){
          rbuCreateTargetSchema(p);
        }

        /* Point the object iterator at the first object */
        if( p->rc==SQLITE_OK ){
          p->rc = rbuObjIterFirst(p, &p->objiter);
        }

        /* If the RBU database contains no data_xxx tables, declare the RBU

    rbuFreeState(pState);
  }

  return p;
}

/*
** Open and return a new RBU handle. 
*/
sqlite3rbu *sqlite3rbu_open(
  const char *zTarget, 
  const char *zRbu,
  const char *zState
){
  /* TODO: Check that zTarget and zRbu are non-NULL */
  return openRbuHandle(zTarget, zRbu, zState);
}

/*
** Open a handle to begin or resume an RBU VACUUM operation.
*/
sqlite3rbu *sqlite3rbu_vacuum(
  const char *zTarget, 
  const char *zState
){
  /* TODO: Check that both arguments are non-NULL */
  return openRbuHandle(0, zTarget, zState);
}

/*
** Return the database handle used by pRbu.
*/
sqlite3 *sqlite3rbu_db(sqlite3rbu *pRbu, int bRbu){
  sqlite3 *db = 0;
  if( pRbu ){

      p->rc = sqlite3_exec(p->dbRbu, "COMMIT", 0, 0, &p->zErrmsg);
    }

    /* Close any open statement handles. */
    rbuObjIterFinalize(&p->objiter);

    /* Close the open database handle and VFS object. */
    sqlite3_close(p->dbRbu);
    sqlite3_close(p->dbMain);
    rbuDeleteVfs(p);
    sqlite3_free(p->aBuf);
    sqlite3_free(p->aFrame);

    rbuEditErrmsg(p);
    rc = p->rc;
    *pzErrmsg = p->zErrmsg;

*/
static u32 rbuGetU32(u8 *aBuf){
  return ((u32)aBuf[0] << 24)
       + ((u32)aBuf[1] << 16)
       + ((u32)aBuf[2] <<  8)
       + ((u32)aBuf[3]);
}

/*
** Write an unsigned 32-bit value in big-endian format to the supplied
** buffer.
*/
static void rbuPutU32(u8 *aBuf, u32 iVal){
  aBuf[0] = (iVal >> 24) & 0xFF;
  aBuf[1] = (iVal >> 16) & 0xFF;
  aBuf[2] = (iVal >>  8) & 0xFF;
  aBuf[3] = (iVal >>  0) & 0xFF;
}

/*
** Write an unsigned 16-bit value in big-endian format to the supplied
** buffer.
*/
static void rbuPutU16(u8 *aBuf, u16 iVal){
  aBuf[0] = (iVal >>  8) & 0xFF;
  aBuf[1] = (iVal >>  0) & 0xFF;
}

/*
** Read data from an rbuVfs-file.
*/
static int rbuVfsRead(
  sqlite3_file *pFile, 
  void *zBuf, 

     && (p->openFlags & SQLITE_OPEN_WAL) 
     && iOfst>=pRbu->iOalSz 
    ){
      rc = SQLITE_OK;
      memset(zBuf, 0, iAmt);
    }else{
      rc = p->pReal->pMethods->xRead(p->pReal, zBuf, iAmt, iOfst);
      /* If this is being called to read the first page of the target 
      ** database as part of an rbu vacuum operation, synthesize the 
      ** contents of the first page if it does not yet exist. Otherwise,
      ** SQLite will not check for a *-wal file.  */
      if( p->pRbu && rbuIsVacuum(p->pRbu) 
       && rc==SQLITE_IOERR_SHORT_READ && iOfst==0
       && (p->openFlags & SQLITE_OPEN_MAIN_DB)
      ){
        sqlite3_file *pFd = 0;
        rc = sqlite3_file_control(
            p->pRbu->dbRbu, "main", SQLITE_FCNTL_FILE_POINTER, (void*)&pFd
        );
        if( rc==SQLITE_OK ){
          rc = pFd->pMethods->xRead(pFd, zBuf, iAmt, iOfst);
        }
        if( rc==SQLITE_OK ){
          rbuPutU32(&zBuf[52], 0);          /* largest root page number */
          rbuPutU32(&zBuf[36], 0);          /* number of free pages */
          rbuPutU32(&zBuf[32], 0);          /* first page on free list trunk */
          rbuPutU32(&zBuf[28], 1);          /* size of db file in pages */

          if( iAmt>100 ){
            assert( iAmt>=101 );
            memset(&zBuf[101], 0, iAmt-101);
            rbuPutU16(&zBuf[105], iAmt & 0xFFFF);
          }
        }
      }
    }
    if( rc==SQLITE_OK && iOfst==0 && (p->openFlags & SQLITE_OPEN_MAIN_DB) ){
      /* These look like magic numbers. But they are stable, as they are part
       ** of the definition of the SQLite file format, which may not change. */
      u8 *pBuf = (u8*)zBuf;
      p->iCookie = rbuGetU32(&pBuf[24]);
      p->iWriteVer = pBuf[19];

}

/*
** Return the current file-size of an rbuVfs-file.
*/
static int rbuVfsFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
  rbu_file *p = (rbu_file *)pFile;
  int rc;
  rc = p->pReal->pMethods->xFileSize(p->pReal, pSize);

  /* If this is an RBU vacuum operation and this is the target database,
  ** pretend that it has at least one page. Otherwise, SQLite will not
  ** check for the existance of a *-wal file. rbuVfsRead() contains 
  ** similar logic.  */
  if( rc==SQLITE_OK && *pSize==0 
   && p->pRbu && rbuIsVacuum(p->pRbu) 
   && (p->openFlags & SQLITE_OPEN_MAIN_DB)
  ){
    *pSize = 1024;
  }
  return rc;
}

/*
** Lock an rbuVfs-file.
*/
static int rbuVfsLock(sqlite3_file *pFile, int eLock){
  rbu_file *p = (rbu_file*)pFile;

** the zipvfs_create_vfs() API below for details on using RBU with zipvfs.
*/
sqlite3rbu *sqlite3rbu_open(
  const char *zTarget, 
  const char *zRbu,
  const char *zState
);

/*
** Open an RBU handle to perform an RBU vacuum database file zTarget.
*/
sqlite3rbu *sqlite3rbu_vacuum(
  const char *zTarget, 
  const char *zState
);

/*
** Internally, each RBU connection uses a separate SQLite database 
** connection to access the target and rbu update databases. This
** API allows the application direct access to these database handles.
**
** The first argument passed to this function must be a valid, open, RBU

  if( objc==5 ) zStateDb = Tcl_GetString(objv[4]);

  pRbu = sqlite3rbu_open(zTarget, zRbu, zStateDb);
  Tcl_CreateObjCommand(interp, zCmd, test_sqlite3rbu_cmd, (ClientData)pRbu, 0);
  Tcl_SetObjResult(interp, objv[1]);
  return TCL_OK;
}

/*
** Tclcmd: sqlite3rbu_vacuum CMD <target-db> <state-db>
*/
static int test_sqlite3rbu_vacuum(
  ClientData clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3rbu *pRbu = 0;
  const char *zCmd;
  const char *zTarget;
  const char *zStateDb = 0;

  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "NAME TARGET-DB STATE-DB");
    return TCL_ERROR;
  }
  zCmd = Tcl_GetString(objv[1]);
  zTarget = Tcl_GetString(objv[2]);
  zStateDb = Tcl_GetString(objv[3]);

  pRbu = sqlite3rbu_vacuum(zTarget, zStateDb);
  Tcl_CreateObjCommand(interp, zCmd, test_sqlite3rbu_cmd, (ClientData)pRbu, 0);
  Tcl_SetObjResult(interp, objv[1]);
  return TCL_OK;
}

/*
** Tclcmd: sqlite3rbu_create_vfs ?-default? NAME PARENT
*/
static int test_sqlite3rbu_create_vfs(
  ClientData clientData,
  Tcl_Interp *interp,

int SqliteRbu_Init(Tcl_Interp *interp){ 
  static struct {
     char *zName;
     Tcl_ObjCmdProc *xProc;
  } aObjCmd[] = {
    { "sqlite3rbu", test_sqlite3rbu },
    { "sqlite3rbu_vacuum", test_sqlite3rbu_vacuum },
    { "sqlite3rbu_create_vfs", test_sqlite3rbu_create_vfs },
    { "sqlite3rbu_destroy_vfs", test_sqlite3rbu_destroy_vfs },
    { "sqlite3rbu_internal_test", test_sqlite3rbu_internal_test },
  };
  int i;
  for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
    Tcl_CreateObjCommand(interp, aObjCmd[i].zName, aObjCmd[i].xProc, 0, 0);