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Overview
Comment:Unless the "--freelist-corrupt" option is specified, do not have the .recover command attempt to recover data from pages that are on the database free-list.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | dbdata
Files: files | file ages | folders
SHA3-256: 8d2f52bb640d6d0f84b18d746043e56f45a73ace93239be1d036701f7f4018fd
User & Date: dan 2019-04-25 19:23:15
Context
2019-04-25
20:06
Merge latest trunk changes into this branch. check-in: 1da302d8 user: dan tags: dbdata
19:23
Unless the "--freelist-corrupt" option is specified, do not have the .recover command attempt to recover data from pages that are on the database free-list. check-in: 8d2f52bb user: dan tags: dbdata
16:20
Fix a bug preventing .recover from working on databases where the final page of the db is corrupt. check-in: 959bbd11 user: dan tags: dbdata
Changes
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Changes to src/shell.c.in.

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    p->lineno = nLine;
  }
  sqlite3_free(a);
  utf8_printf(stderr,"Error on line %d of --hexdb input\n", nLine);
  return 0;
}
#endif /* SQLITE_ENABLE_DESERIALIZE */






























/*
** Scalar function "shell_escape_crnl" used by the .recover command.
** The argument passed to this function is the output of built-in
** function quote(). If the first character of the input is "'", 
** indicating that the value passed to quote() was a text value,
** then this function searches the input for "\n" and "\r" characters
................................................................................
                            shellAddSchemaName, 0, 0);
    sqlite3_create_function(p->db, "shell_module_schema", 1, SQLITE_UTF8, 0,
                            shellModuleSchema, 0, 0);
    sqlite3_create_function(p->db, "shell_putsnl", 1, SQLITE_UTF8, p,
                            shellPutsFunc, 0, 0);
    sqlite3_create_function(p->db, "shell_escape_crnl", 1, SQLITE_UTF8, 0,
                            shellEscapeCrnl, 0, 0);


#ifndef SQLITE_NOHAVE_SYSTEM
    sqlite3_create_function(p->db, "edit", 1, SQLITE_UTF8, 0,
                            editFunc, 0, 0);
    sqlite3_create_function(p->db, "edit", 2, SQLITE_UTF8, 0,
                            editFunc, 0, 0);
#endif
    if( p->openMode==SHELL_OPEN_ZIPFILE ){
................................................................................
** 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 */




















  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)"
................................................................................
    /* 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 the "map" table that will (eventually) contain instructions
    ** for dealing with each page in the db that contains one or more 
    ** records. */
    "CREATE TABLE recovery.map("
      "pgno INTEGER PRIMARY KEY, maxlen INT, intkey, root INT"
    ");"

................................................................................
    "      SELECT 0, i, (SELECT pgno FROM recovery.dbptr WHERE child=i)"
    "        UNION ALL"
    "      SELECT i, p.parent, "
    "        (SELECT pgno FROM recovery.dbptr WHERE child=p.parent) FROM p"
    "    )"
    "    SELECT pgno FROM p WHERE (parent IS NULL OR pgno = orig)"
    ") "
    "FROM pages WHERE maxlen > 0;"
    "UPDATE recovery.map AS o SET intkey = ("
    "  SELECT substr(data, 1, 1)==X'0D' FROM sqlite_dbpage WHERE pgno=o.pgno"
    ");"

    /* Extract data from page 1 and any linked pages into table
    ** recovery.schema. With the same schema as an sqlite_master table.  */
    "CREATE TABLE recovery.schema(type, name, tbl_name, rootpage, sql);"







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    p->lineno = nLine;
  }
  sqlite3_free(a);
  utf8_printf(stderr,"Error on line %d of --hexdb input\n", nLine);
  return 0;
}
#endif /* SQLITE_ENABLE_DESERIALIZE */

/*
** Scalar function "shell_int32". The first argument to this function
** must be a blob. The second a non-negative integer. This function
** reads and returns a 32-bit big-endian integer from byte
** offset (4*<arg2>) of the blob.
*/
static void shellInt32(
  sqlite3_context *context, 
  int argc, 
  sqlite3_value **argv
){
  const unsigned char *pBlob;
  int nBlob;
  int iInt;
  
  nBlob = sqlite3_value_bytes(argv[0]);
  pBlob = (const unsigned char*)sqlite3_value_blob(argv[0]);
  iInt = sqlite3_value_int(argv[1]);

  if( iInt>=0 && (iInt+1)*4<=nBlob ){
    const unsigned char *a = &pBlob[iInt*4];
    sqlite3_int64 iVal = ((sqlite3_int64)a[0]<<24)
                       + ((sqlite3_int64)a[1]<<16)
                       + ((sqlite3_int64)a[2]<< 8)
                       + ((sqlite3_int64)a[3]<< 0);
    sqlite3_result_int64(context, iVal);
  }
}

/*
** Scalar function "shell_escape_crnl" used by the .recover command.
** The argument passed to this function is the output of built-in
** function quote(). If the first character of the input is "'", 
** indicating that the value passed to quote() was a text value,
** then this function searches the input for "\n" and "\r" characters
................................................................................
                            shellAddSchemaName, 0, 0);
    sqlite3_create_function(p->db, "shell_module_schema", 1, SQLITE_UTF8, 0,
                            shellModuleSchema, 0, 0);
    sqlite3_create_function(p->db, "shell_putsnl", 1, SQLITE_UTF8, p,
                            shellPutsFunc, 0, 0);
    sqlite3_create_function(p->db, "shell_escape_crnl", 1, SQLITE_UTF8, 0,
                            shellEscapeCrnl, 0, 0);
    sqlite3_create_function(p->db, "shell_int32", 2, SQLITE_UTF8, 0,
                            shellInt32, 0, 0);
#ifndef SQLITE_NOHAVE_SYSTEM
    sqlite3_create_function(p->db, "edit", 1, SQLITE_UTF8, 0,
                            editFunc, 0, 0);
    sqlite3_create_function(p->db, "edit", 2, SQLITE_UTF8, 0,
                            editFunc, 0, 0);
#endif
    if( p->openMode==SHELL_OPEN_ZIPFILE ){
................................................................................
** 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)"
................................................................................
    /* 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 "
      "      WHERE x>0"
      "    UNION"
      "  SELECT shell_int32("
      "      (SELECT data FROM sqlite_dbpage WHERE pgno=trunk.pgno), 0) AS x "
      "      FROM trunk WHERE x>0"
      "),"
      "freelist(data, n, freepgno) AS ("
      "  SELECT data, shell_int32(data, 1)-1, t.pgno "
      "      FROM trunk t, sqlite_dbpage s WHERE s.pgno=t.pgno"
      "    UNION ALL"
      "  SELECT data, n-1, shell_int32(data, 2+n) "
      "      FROM freelist WHERE n>=0"
      ")"
      "REPLACE INTO recovery.freelist SELECT freepgno FROM freelist;"
    );
  }

  shellExec(pState->db, &rc, 
    /* Create the "map" table that will (eventually) contain instructions
    ** for dealing with each page in the db that contains one or more 
    ** records. */
    "CREATE TABLE recovery.map("
      "pgno INTEGER PRIMARY KEY, maxlen INT, intkey, root INT"
    ");"

................................................................................
    "      SELECT 0, i, (SELECT pgno FROM recovery.dbptr WHERE child=i)"
    "        UNION ALL"
    "      SELECT i, p.parent, "
    "        (SELECT pgno FROM recovery.dbptr WHERE child=p.parent) FROM p"
    "    )"
    "    SELECT pgno FROM p WHERE (parent IS NULL OR pgno = orig)"
    ") "
    "FROM pages WHERE maxlen > 0 AND i NOT IN freelist;"
    "UPDATE recovery.map AS o SET intkey = ("
    "  SELECT substr(data, 1, 1)==X'0D' FROM sqlite_dbpage WHERE pgno=o.pgno"
    ");"

    /* Extract data from page 1 and any linked pages into table
    ** recovery.schema. With the same schema as an sqlite_master table.  */
    "CREATE TABLE recovery.schema(type, name, tbl_name, rootpage, sql);"