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Overview
Comment:Fix a locking-page related problem with the ".recover" command.
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SHA3-256: afdae10424f0f3d0f10a4b73e9732aa55c5ee664814d8ca0edd372cfb17c2445
User & Date: dan 2019-04-26 15:14:53
Context
2019-04-26
15:40
Fix another problem with database freelist handling in the ".recover" command. check-in: bee2652a user: dan tags: dbdata
15:14
Fix a locking-page related problem with the ".recover" command. check-in: afdae104 user: dan tags: dbdata
2019-04-25
20:06
Merge latest trunk changes into this branch. check-in: 1da302d8 user: dan tags: dbdata
Changes
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Changes to ext/misc/dbdata.c.

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  int iPgno;                      /* Current page number */
  u8 *aPage;                      /* Buffer containing page */
  int nPage;                      /* Size of aPage[] in bytes */
  int nCell;                      /* Number of cells on aPage[] */
  int iCell;                      /* Current cell number */
  int bOnePage;                   /* True to stop after one page */

  sqlite3_int64 iRowid;

  /* Only for the sqlite_dbdata table */
  u8 *pRec;                       /* Buffer containing current record */
  int nRec;                       /* Size of pRec[] in bytes */
  int nHdr;                       /* Size of header in bytes */
  int iField;                     /* Current field number */
................................................................................
  sqlite3_stmt *pStmt = pCsr->pStmt;

  *ppPage = 0;
  *pnPage = 0;
  sqlite3_bind_int64(pStmt, 2, pgno);
  if( SQLITE_ROW==sqlite3_step(pStmt) ){
    int nCopy = sqlite3_column_bytes(pStmt, 0);


    u8 *pPage = (u8*)sqlite3_malloc64(nCopy);
    if( pPage==0 ){
      rc = SQLITE_NOMEM;
    }else{
      const u8 *pCopy = sqlite3_column_blob(pStmt, 0);
      memcpy(pPage, pCopy, nCopy);

      *ppPage = pPage;
      *pnPage = nCopy;
    }
  }
  rc2 = sqlite3_reset(pStmt);
  if( *ppPage==0 ) rc = rc2;

  return rc;
}

/*
** Read a varint.  Put the value in *pVal and return the number of bytes.
*/
................................................................................

  pCsr->iRowid++;
  while( 1 ){
    int rc;
    int iOff = (pCsr->iPgno==1 ? 100 : 0);

    if( pCsr->aPage==0 ){


      rc = dbdataLoadPage(pCsr, pCsr->iPgno, &pCsr->aPage, &pCsr->nPage);
      if( rc!=SQLITE_OK || pCsr->aPage==0 ) return rc;



      pCsr->iCell = pTab->bPtr ? -2 : 0;
      pCsr->nCell = get_uint16(&pCsr->aPage[iOff+3]);
    }

    if( pTab->bPtr ){
      if( pCsr->aPage[iOff]!=0x02 && pCsr->aPage[iOff]!=0x05 ){
        pCsr->iCell = pCsr->nCell;
................................................................................
/* We have reached EOF if previous sqlite3_step() returned
** anything other than SQLITE_ROW;
*/
static int dbdataEof(sqlite3_vtab_cursor *pCursor){
  DbdataCursor *pCsr = (DbdataCursor*)pCursor;
  return pCsr->aPage==0;
}



















/* Position a cursor back to the beginning.
*/
static int dbdataFilter(
  sqlite3_vtab_cursor *pCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
................................................................................
  assert( pCsr->iPgno==1 );
  if( idxNum & 0x01 ){
    zSchema = (const char*)sqlite3_value_text(argv[0]);
  }
  if( idxNum & 0x02 ){
    pCsr->iPgno = sqlite3_value_int(argv[(idxNum & 0x01)]);
    pCsr->bOnePage = 1;



  }


  if( pTab->pStmt ){
    pCsr->pStmt = pTab->pStmt;
    pTab->pStmt = 0;
  }else{
    rc = sqlite3_prepare_v2(pTab->db, 
        "SELECT data FROM sqlite_dbpage(?) WHERE pgno=?", -1,
        &pCsr->pStmt, 0
    );

  }
  if( rc==SQLITE_OK ){
    rc = sqlite3_bind_text(pCsr->pStmt, 1, zSchema, -1, SQLITE_TRANSIENT);
  }else{
    pTab->base.zErrMsg = sqlite3_mprintf("%s", sqlite3_errmsg(pTab->db));
  }
  if( rc==SQLITE_OK ){







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  int iPgno;                      /* Current page number */
  u8 *aPage;                      /* Buffer containing page */
  int nPage;                      /* Size of aPage[] in bytes */
  int nCell;                      /* Number of cells on aPage[] */
  int iCell;                      /* Current cell number */
  int bOnePage;                   /* True to stop after one page */
  int szDb;
  sqlite3_int64 iRowid;

  /* Only for the sqlite_dbdata table */
  u8 *pRec;                       /* Buffer containing current record */
  int nRec;                       /* Size of pRec[] in bytes */
  int nHdr;                       /* Size of header in bytes */
  int iField;                     /* Current field number */
................................................................................
  sqlite3_stmt *pStmt = pCsr->pStmt;

  *ppPage = 0;
  *pnPage = 0;
  sqlite3_bind_int64(pStmt, 2, pgno);
  if( SQLITE_ROW==sqlite3_step(pStmt) ){
    int nCopy = sqlite3_column_bytes(pStmt, 0);
    if( nCopy>0 ){
      u8 *pPage;
      pPage = (u8*)sqlite3_malloc64(nCopy);
      if( pPage==0 ){
        rc = SQLITE_NOMEM;
      }else{
        const u8 *pCopy = sqlite3_column_blob(pStmt, 0);
        memcpy(pPage, pCopy, nCopy);
      }
      *ppPage = pPage;
      *pnPage = nCopy;
    }
  }
  rc2 = sqlite3_reset(pStmt);
  if( rc==SQLITE_OK ) rc = rc2;

  return rc;
}

/*
** Read a varint.  Put the value in *pVal and return the number of bytes.
*/
................................................................................

  pCsr->iRowid++;
  while( 1 ){
    int rc;
    int iOff = (pCsr->iPgno==1 ? 100 : 0);

    if( pCsr->aPage==0 ){
      while( 1 ){
        if( pCsr->bOnePage==0 && pCsr->iPgno>pCsr->szDb ) return SQLITE_OK;
        rc = dbdataLoadPage(pCsr, pCsr->iPgno, &pCsr->aPage, &pCsr->nPage);
        if( rc!=SQLITE_OK ) return rc;
        if( pCsr->aPage ) break;
        pCsr->iPgno++;
      }
      pCsr->iCell = pTab->bPtr ? -2 : 0;
      pCsr->nCell = get_uint16(&pCsr->aPage[iOff+3]);
    }

    if( pTab->bPtr ){
      if( pCsr->aPage[iOff]!=0x02 && pCsr->aPage[iOff]!=0x05 ){
        pCsr->iCell = pCsr->nCell;
................................................................................
/* We have reached EOF if previous sqlite3_step() returned
** anything other than SQLITE_ROW;
*/
static int dbdataEof(sqlite3_vtab_cursor *pCursor){
  DbdataCursor *pCsr = (DbdataCursor*)pCursor;
  return pCsr->aPage==0;
}

static int dbdataDbsize(DbdataCursor *pCsr, const char *zSchema){
  DbdataTable *pTab = (DbdataTable*)pCsr->base.pVtab;
  char *zSql = 0;
  int rc, rc2;
  sqlite3_stmt *pStmt = 0;

  zSql = sqlite3_mprintf("PRAGMA %Q.page_count", zSchema);
  if( zSql==0 ) return SQLITE_NOMEM;
  rc = sqlite3_prepare_v2(pTab->db, zSql, -1, &pStmt, 0);
  sqlite3_free(zSql);
  if( rc==SQLITE_OK && sqlite3_step(pStmt)==SQLITE_ROW ){
    pCsr->szDb = sqlite3_column_int(pStmt, 0);
  }
  rc2 = sqlite3_finalize(pStmt);
  if( rc==SQLITE_OK ) rc = rc2;
  return rc;
}

/* Position a cursor back to the beginning.
*/
static int dbdataFilter(
  sqlite3_vtab_cursor *pCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
................................................................................
  assert( pCsr->iPgno==1 );
  if( idxNum & 0x01 ){
    zSchema = (const char*)sqlite3_value_text(argv[0]);
  }
  if( idxNum & 0x02 ){
    pCsr->iPgno = sqlite3_value_int(argv[(idxNum & 0x01)]);
    pCsr->bOnePage = 1;
  }else{
    pCsr->nPage = dbdataDbsize(pCsr, zSchema);
    rc = dbdataDbsize(pCsr, zSchema);
  }

  if( rc==SQLITE_OK ){
    if( pTab->pStmt ){
      pCsr->pStmt = pTab->pStmt;
      pTab->pStmt = 0;
    }else{
      rc = sqlite3_prepare_v2(pTab->db, 
          "SELECT data FROM sqlite_dbpage(?) WHERE pgno=?", -1,
          &pCsr->pStmt, 0
      );
    }
  }
  if( rc==SQLITE_OK ){
    rc = sqlite3_bind_text(pCsr->pStmt, 1, zSchema, -1, SQLITE_TRANSIENT);
  }else{
    pTab->base.zErrMsg = sqlite3_mprintf("%s", sqlite3_errmsg(pTab->db));
  }
  if( rc==SQLITE_OK ){

Changes to src/shell.c.in.

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    rc = sqlite3_exec(db, zSql, 0, 0, &zErr);
    if( rc!=SQLITE_OK ){
      raw_printf(stderr, "SQL error: %s\n", zErr);
    }
    *pRc = rc;
  }
}

















static void *shellMalloc(int *pRc, sqlite3_int64 nByte){
  void *pRet = 0;
  if( *pRc==SQLITE_OK ){
    pRet = sqlite3_malloc64(nByte);
    if( pRet==0 ){
      *pRc = SQLITE_NOMEM;
................................................................................
** on stream pState->out.
*/
static int recoverDatabaseCmd(ShellState *pState, int nArg, char **azArg){
  int rc = SQLITE_OK;
  sqlite3_stmt *pLoop = 0;        /* Loop through all root pages */
  sqlite3_stmt *pPages = 0;       /* Loop through all pages in a group */
  sqlite3_stmt *pCells = 0;       /* Loop through all cells in a page */

  int i;

  int bFreelist = 1;              /* 0 if --freelist-corrupt is specified */
  for(i=1; i<nArg; i++){
    char *z = azArg[i];
    int n;
    if( z[0]=='-' && z[1]=='-' ) z++;
    n = strlen(z);
    if( n<=17 && memcmp("-freelist-corrupt", z, n)==0 ){
      bFreelist = 0;
    }
    else{
      raw_printf(stderr, 
        "unexpected option: %s - expected \"--freelist-corrupt\"\n", 
        azArg[i]
      );




      return 1;
    }
  }

  shellExec(pState->db, &rc, 
    /* Attach an in-memory database named 'recovery'. Create an indexed 
    ** cache of the sqlite_dbptr virtual table. */
    "ATTACH '' AS recovery;"




    "CREATE TABLE recovery.dbptr("
    "      pgno, child, PRIMARY KEY(child, pgno)"
    ") WITHOUT ROWID;"

    "INSERT OR IGNORE INTO dbptr(pgno, child) SELECT * FROM sqlite_dbptr;"

    /* Delete any pointer to page 1. This ensures that page 1 is considered
    ** a root page, regardless of how corrupt the db is. */
    "DELETE FROM recovery.dbptr WHERE child = 1;"

    /* Delete all pointers to any pages that have more than one pointer
    ** to them. Such pages will be treated as root pages when recovering
    ** data.  */
    "DELETE FROM recovery.dbptr WHERE child IN ("
    "  SELECT child FROM recovery.dbptr GROUP BY child HAVING count(*)>1"
    ");"

    "CREATE TABLE recovery.freelist(pgno INTEGER PRIMARY KEY);"
  );

  if( bFreelist ){
    shellExec(pState->db, &rc,
      "WITH trunk(pgno) AS ("
      "  SELECT shell_int32("
      "      (SELECT data FROM sqlite_dbpage WHERE pgno=1), 8) AS x "







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    rc = sqlite3_exec(db, zSql, 0, 0, &zErr);
    if( rc!=SQLITE_OK ){
      raw_printf(stderr, "SQL error: %s\n", zErr);
    }
    *pRc = rc;
  }
}

static void shellExecPrintf(sqlite3 *db, int *pRc, const char *zFmt, ...){
  char *z = 0;
  if( *pRc==SQLITE_OK ){
    va_list ap;
    va_start(ap, zFmt);
    z = sqlite3_vmprintf(zFmt, ap);
    va_end(ap);
    if( z==0 ){
      *pRc = SQLITE_NOMEM;
    }else{
      shellExec(db, pRc, z);
    }
    sqlite3_free(z);
  }
}

static void *shellMalloc(int *pRc, sqlite3_int64 nByte){
  void *pRet = 0;
  if( *pRc==SQLITE_OK ){
    pRet = sqlite3_malloc64(nByte);
    if( pRet==0 ){
      *pRc = SQLITE_NOMEM;
................................................................................
** on stream pState->out.
*/
static int recoverDatabaseCmd(ShellState *pState, int nArg, char **azArg){
  int rc = SQLITE_OK;
  sqlite3_stmt *pLoop = 0;        /* Loop through all root pages */
  sqlite3_stmt *pPages = 0;       /* Loop through all pages in a group */
  sqlite3_stmt *pCells = 0;       /* Loop through all cells in a page */
  const char *zRecoveryDb = "";   /* Name of "recovery" database */
  int i;

  int bFreelist = 1;              /* 0 if --freelist-corrupt is specified */
  for(i=1; i<nArg; i++){
    char *z = azArg[i];
    int n;
    if( z[0]=='-' && z[1]=='-' ) z++;
    n = strlen(z);
    if( n<=17 && memcmp("-freelist-corrupt", z, n)==0 ){
      bFreelist = 0;
    }
    if( n<=12 && memcmp("-recovery-db", z, n)==0 && i<(nArg-1) ){
      i++;
      zRecoveryDb = azArg[i];
    }
    else{
      raw_printf(stderr, "unexpected option: %s\n", azArg[i]); 
      raw_printf(stderr, "options are:\n");
      raw_printf(stderr, "    --freelist-corrupt\n");
      raw_printf(stderr, "    --recovery-db DATABASE\n");
      return 1;
    }
  }

  shellExecPrintf(pState->db, &rc,
    /* Attach an in-memory database named 'recovery'. Create an indexed 
    ** cache of the sqlite_dbptr virtual table. */
    "ATTACH %Q AS recovery;"
    "DROP TABLE IF EXISTS recovery.dbptr;"
    "DROP TABLE IF EXISTS recovery.freelist;"
    "DROP TABLE IF EXISTS recovery.map;"
    "DROP TABLE IF EXISTS recovery.schema;"
    "CREATE TABLE recovery.dbptr("
    "      pgno, child, PRIMARY KEY(child, pgno)"
    ") WITHOUT ROWID;"
    "INSERT OR IGNORE INTO recovery.dbptr(pgno, child) "
    "    SELECT * FROM sqlite_dbptr;"

    /* Delete any pointer to page 1. This ensures that page 1 is considered
    ** a root page, regardless of how corrupt the db is. */
    "DELETE FROM recovery.dbptr WHERE child = 1;"

    /* Delete all pointers to any pages that have more than one pointer
    ** to them. Such pages will be treated as root pages when recovering
    ** data.  */
    "DELETE FROM recovery.dbptr WHERE child IN ("
    "  SELECT child FROM recovery.dbptr GROUP BY child HAVING count(*)>1"
    ");"

    "CREATE TABLE recovery.freelist(pgno INTEGER PRIMARY KEY);", zRecoveryDb
  );

  if( bFreelist ){
    shellExec(pState->db, &rc,
      "WITH trunk(pgno) AS ("
      "  SELECT shell_int32("
      "      (SELECT data FROM sqlite_dbpage WHERE pgno=1), 8) AS x "