SQLite

/*
** 2004 April 6
**
** 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.
**
*************************************************************************
** $Id: btree.c,v 1.530 2008/11/11 20:51:51 shane Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"

  assert( idx>=0 && idx<pPage->nCell );
  assert( sz==cellSize(pPage, idx) );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  data = pPage->aData;
  ptr = &data[pPage->cellOffset + 2*idx];
  /* mask the cell offset to ensure a corrupt db does not result in a crash */
  pc = pPage->maskPage & get2byte(ptr);
  assert( pc>10 && pc+sz<=pPage->pBt->usableSize );
  freeSpace(pPage, pc, sz);
  for(i=idx+1; i<pPage->nCell; i++, ptr+=2){
    ptr[0] = ptr[2];
    ptr[1] = ptr[3];
  }
  pPage->nCell--;

# This file implements regression tests for SQLite library.
#
# This file implements tests to make sure SQLite does not crash or
# segfault if it sees a corrupt database file.  It creates a base
# data base file, then tests that single byte corruptions in 
# increasingly larger quantities are handled gracefully.
#
# $Id: corruptC.test,v 1.3 2008/11/11 20:51:51 shane Exp $

catch {file delete -force test.db test.db-journal test.bu}

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Set a uniform random seed
expr srand(0)

# Construct a compact, dense database for testing.
#
do_test corruptC-1.1 {
  execsql {
    BEGIN;
    CREATE TABLE t1(x,y);
    INSERT INTO t1 VALUES(1,1);
    INSERT OR IGNORE INTO t1 SELECT x*2,y FROM t1;
    INSERT OR IGNORE INTO t1 SELECT x*3,y FROM t1;
    INSERT OR IGNORE INTO t1 SELECT x*5,y FROM t1;
    INSERT OR IGNORE INTO t1 SELECT x*7,y FROM t1;
    INSERT OR IGNORE INTO t1 SELECT x*11,y FROM t1;
    INSERT OR IGNORE INTO t1 SELECT x*13,y FROM t1;
    CREATE INDEX t1i1 ON t1(x);
    CREATE TABLE t2 AS SELECT x,2 FROM t1 WHERE rowid%5!=0;
    COMMIT;
  }
} {}

ifcapable {integrityck} {
  integrity_check corruptC-1.2
}

  puts -nonewline $t [read $f [file size $from]]
  close $t
  close $f
}

# Setup for the tests.  Make a backup copy of the good database in test.bu.
#
db close
copy_file test.db test.bu
sqlite3 db test.db
set fsize [file size test.db]

#
# first test some specific corruption tests found from earlier runs
#

# test that a corrupt content offset size is handled (seed 5577)
do_test corruptC-2.1 {
  db close
  copy_file test.bu test.db

  # insert corrupt byte(s)
  hexio_write test.db 2053 [format %02x 0x04]

  sqlite3 db test.db
  catchsql {PRAGMA integrity_check}
} {0 {{*** in database main ***
Corruption detected in header on page 3
Multiple uses for byte 604 of page 3}}}

# test that a corrupt content offset size is handled (seed 5649)
do_test corruptC-2.2 {
  db close
  copy_file test.bu test.db

  # insert corrupt byte(s)
  hexio_write test.db 27   [format %02x 0x08]
  hexio_write test.db 233  [format %02x 0x6a]
  hexio_write test.db 328  [format %02x 0x67]
  hexio_write test.db 750  [format %02x 0x1f]
  hexio_write test.db 1132 [format %02x 0x52]
  hexio_write test.db 1133 [format %02x 0x84]
  hexio_write test.db 1220 [format %02x 0x01]
  hexio_write test.db 3688 [format %02x 0xc1]
  hexio_write test.db 3714 [format %02x 0x58]
  hexio_write test.db 3746 [format %02x 0x9a]

  sqlite3 db test.db
  catchsql {UPDATE t1 SET y=1}
} {0 {}}

#
# now test for a series of quasi-random seeds
#
for {set tn 0} {$tn<=1024} {incr tn 1} {

  # Set a quasi-random random seed
  expr srand($tn)

  # setup for test
  db close
  copy_file test.bu test.db
  sqlite3 db test.db

  # Seek to a random location in the file, and write a random single byte
  # value.  Then do various operations on the file to make sure that
  # the database engine can handle the corruption gracefully.
  #
  set last 0
  for {set i 1} {$i<=1024 && !$last} {incr i 1} {

    # insert random byte at random location
    db close
    hexio_write test.db [random $fsize] [format %02x [random 255]]
    sqlite3 db test.db

    # do a few random operations to make sure that if 
    # they error, they error gracefully instead of crashing.
    do_test corruptC-3.$tn.$i.1 {

      catchsql {SELECT count(*) FROM sqlite_master}
      set x {}
    } {}
    do_test corruptC-3.$tn.$i.2 {
      catchsql {SELECT count(*) FROM t1}
      set x {}
    } {}
    do_test corruptC-3.$tn.$i.3 {
      catchsql {SELECT count(*) FROM t1 WHERE x>13}
      set x {}
    } {}
    do_test corruptC-3.$tn.$i.4 {
      catchsql {SELECT count(*) FROM t2}
      set x {}
    } {}
    do_test corruptC-3.$tn.$i.5 {
      catchsql {SELECT count(*) FROM t2 WHERE x<13}
      set x {}
    } {}
    do_test corruptC-3.$tn.$i.6 {
      catchsql {UPDATE t1 SET y=1}
      set x {}
    } {}
    do_test corruptC-3.$tn.$i.7 {
      catchsql {UPDATE t2 SET y=2}
      set x {}
    } {}

    # check the integrity of the database.
    # once the corruption is detected, we can stop.
    ifcapable {integrityck} {
      set res [ catchsql {PRAGMA integrity_check} ]
      set ans [lindex $res 1]
      if { [ string compare $ans "ok" ] != 0 } {
        set last -1
      }
    }
    # if we are not capable of doing an integrity check,
    # stop after corrupting 5 bytes.
    ifcapable {!integrityck} {
      if { $i > 5 } {
        set last -1
      }
    }

    # Check that no page references were leaked.
    do_test corruptC-3.$tn.$i.8 {
      set bt [btree_from_db db]
      db_enter db
      array set stats [btree_pager_stats $bt]
      db_leave db
      set stats(ref)
    } {0}

  }
  # end for i

}
# end for tn

finish_test