SQLite

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.545 2009/01/10 16:15:09 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"

/*
** Macros for troubleshooting.  Normally turned off
*/

# define CODEC1(P,D,N,X) if( P->xCodec!=0 ){ P->xCodec(P->pCodecArg,D,N,X); }
# define CODEC2(P,D,N,X) ((char*)(P->xCodec!=0?P->xCodec(P->pCodecArg,D,N,X):D))
#else
# define CODEC1(P,D,N,X) /* NO-OP */
# define CODEC2(P,D,N,X) ((char*)D)
#endif

/*
** The maximum allowed sector size. 16MB. If the xSectorsize() method 
** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
** This could conceivably cause corruption following a power failure on
** such a system. This is currently an undocumented limit.
*/
#define MAX_SECTOR_SIZE 0x0100000

/*
** An instance of the following structure is allocated for each active
** savepoint and statement transaction in the system. All such structures
** are stored in the Pager.aSavepoint[] array, which is allocated and
** resized using sqlite3Realloc().
**
** When a savepoint is created, the PagerSavepoint.iHdrOffset field is

  int dc;           /* Device characteristics */
  int nSector;      /* Sector size */
  int szPage;        /* Page size */
  sqlite3_file *fd = pPager->fd;

  if( fd->pMethods ){
    dc = sqlite3OsDeviceCharacteristics(fd);
    nSector = pPager->sectorSize;
    szPage = pPager->pageSize;
  }

  assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
  assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));

  if( !fd->pMethods || 

  i64 journalSize,
  u32 *pNRec, 
  u32 *pDbSize
){
  int rc;
  unsigned char aMagic[8]; /* A buffer to hold the magic header */
  i64 jrnlOff;
  u32 iPageSize;
  u32 iSectorSize;

  seekJournalHdr(pPager);
  if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
    return SQLITE_DONE;
  }
  jrnlOff = pPager->journalOff;

  rc = read32bits(pPager->jfd, jrnlOff+4, &pPager->cksumInit);
  if( rc ) return rc;

  rc = read32bits(pPager->jfd, jrnlOff+8, pDbSize);
  if( rc ) return rc;

  if( pPager->journalOff==0 ){
    rc = read32bits(pPager->jfd, jrnlOff+16, &iPageSize);
    if( rc ) return rc;

    if( iPageSize<512 
     || iPageSize>SQLITE_MAX_PAGE_SIZE 
     || ((iPageSize-1)&iPageSize)!=0 
    ){
      /* If the page-size in the journal-header is invalid, then the process
      ** that wrote the journal-header must have crashed before the header
      ** was synced. In this case stop reading the journal file here.
      */
      rc = SQLITE_DONE;
    }else{
      u16 pagesize = (u16)iPageSize;
      rc = sqlite3PagerSetPagesize(pPager, &pagesize);
      assert( rc!=SQLITE_OK || pagesize==(u16)iPageSize );
    }
    if( rc ) return rc;
  
    /* Update the assumed sector-size to match the value used by 
    ** the process that created this journal. If this journal was
    ** created by a process other than this one, then this routine
    ** is being called from within pager_playback(). The local value
    ** of Pager.sectorSize is restored at the end of that routine.
    */
    rc = read32bits(pPager->jfd, jrnlOff+12, &iSectorSize);
    if( rc ) return rc;
    if( (iSectorSize&(iSectorSize-1))
      || iSectorSize<512
      || iSectorSize>MAX_SECTOR_SIZE
    ){
      return SQLITE_DONE;
    }
    pPager->sectorSize = iSectorSize;
  }

  pPager->journalOff += JOURNAL_HDR_SZ(pPager);
  return SQLITE_OK;
}

  return rc;
}

/*
** Set the sectorSize for the given pager.
**
** The sector size is at least as big as the sector size reported
** by sqlite3OsSectorSize(). The minimum sector size is 512.
*/
static void setSectorSize(Pager *pPager){
  assert(pPager->fd->pMethods||pPager->tempFile);
  if( !pPager->tempFile ){
    /* Sector size doesn't matter for temporary files. Also, the file
    ** may not have been opened yet, in whcih case the OsSectorSize()
    ** call will segfault.
    */
    pPager->sectorSize = sqlite3OsSectorSize(pPager->fd);
  }
  if( pPager->sectorSize<512 ){
    pPager->sectorSize = 512;
  }
  if( pPager->sectorSize>MAX_SECTOR_SIZE ){
    pPager->sectorSize = MAX_SECTOR_SIZE;
  }
}

/*
** Playback the journal and thus restore the database file to
** the state it was in before we started making changes.  
**

      ** database file. The default page size is the maximum of:
      **
      **    + SQLITE_DEFAULT_PAGE_SIZE,
      **    + The value returned by sqlite3OsSectorSize()
      **    + The largest page size that can be written atomically.
      */
      if( rc==SQLITE_OK && !readOnly ){
        setSectorSize(pPager);
        if( szPageDflt<pPager->sectorSize ){
          szPageDflt = pPager->sectorSize;
        }
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
        {
          int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
          int ii;
          assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
          assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** 
** This file defines various limits of what SQLite can process.
**
** @(#) $Id: sqliteLimit.h,v 1.10 2009/01/10 16:15:09 danielk1977 Exp $
*/

/*
** The maximum length of a TEXT or BLOB in bytes.   This also
** limits the size of a row in a table or index.
**
** The hard limit is the ability of a 32-bit signed integer

#ifndef SQLITE_MAX_VARIABLE_NUMBER
# define SQLITE_MAX_VARIABLE_NUMBER 999
#endif

/* Maximum page size.  The upper bound on this value is 32768.  This a limit
** imposed by the necessity of storing the value in a 2-byte unsigned integer
** and the fact that the page size must be a power of 2.
**
** If this limit is changed, then the compiled library is technically
** incompatible with an SQLite library compiled with a different limit. If
** a process operating on a database with a page-size of 65536 bytes 
** crashes, then an instance of SQLite compiled with the default page-size 
** limit will not be able to rollback the aborted transaction. This could
** lead to database corruption.
*/
#ifndef SQLITE_MAX_PAGE_SIZE
# define SQLITE_MAX_PAGE_SIZE 32768
#endif


/*

#
# This test verifies a couple of specific potential data corruption 
# scenarios involving crashes or power failures.
#
# Later: Also, some other specific scenarios required for coverage
# testing that do not lead to corruption.
#
# $Id: crash8.test,v 1.3 2009/01/10 16:15:09 danielk1977 Exp $


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

ifcapable !crashtest {
  finish_test

proc read_file {zFile} {
  set fd [open $zFile]
  fconfigure $fd -translation binary 
  set zData [read $fd]
  close $fd
  return $zData
}
proc write_file {zFile zData} {
  set fd [open $zFile w]
  fconfigure $fd -translation binary 
  puts -nonewline $fd $zData
  close $fd
}

# The following tests check that SQLite will not roll back a hot-journal
# file if the sector-size field in the first journal file header is
# suspect. Definition of suspect:
# 
#    a) Not a power of 2, or                (crash8-3.5)
#    b) Greater than 0x01000000 (16MB), or  (crash8-3.6)
#    c) Less than 512.                      (crash8-3.7)
#
# Also test that SQLite will not rollback a hot-journal file with a
# suspect page-size. In this case "suspect" means:
# 
#    a) Not a power of 2, or
#    b) Less than 512, or
#    c) Greater than SQLITE_MAX_PAGE_SIZE
#
do_test crash8-3.1 {
  list [file exists test.db-joural] [file exists test.db]
} {0 1}
do_test crash8-3.2 {
  execsql {
    PRAGMA synchronous = off;

    SELECT count(*) FROM t1;
  }
} {0}
do_test crash8-3.4 {
  binary scan [string range $zJournal 20 23] I nSector
  set nSector
} {512}

do_test crash8-3.5 {

  set zJournal2 [string replace $zJournal 20 23 [binary format I 513]]

  write_file test.db-journal $zJournal2




  execsql { 
    SELECT count(*) FROM t1;
    PRAGMA integrity_check
  }
} {0 ok}
do_test crash8-3.6 {

  set zJournal2 [string replace $zJournal 20 23 [binary format I 0x2000000]]

  write_file test.db-journal $zJournal2



  execsql { 
    SELECT count(*) FROM t1;
    PRAGMA integrity_check
  }
} {0 ok}
do_test crash8-3.7 {
  set zJournal2 [string replace $zJournal 20 23 [binary format I 256]]
  write_file test.db-journal $zJournal2
  execsql { 
    SELECT count(*) FROM t1;
    PRAGMA integrity_check
  }
} {0 ok}

do_test crash8-3.8 {
  set zJournal2 [string replace $zJournal 24 27 [binary format I 513]]
  write_file test.db-journal $zJournal2

  execsql { 
    SELECT count(*) FROM t1;
    PRAGMA integrity_check
  }
} {0 ok}
do_test crash8-3.9 {
  set big [expr $SQLITE_MAX_PAGE_SIZE * 2]
  set zJournal2 [string replace $zJournal 24 27 [binary format I $big]]
  write_file test.db-journal $zJournal2
  execsql { 
    SELECT count(*) FROM t1;
    PRAGMA integrity_check
  }
} {0 ok}
do_test crash8-3.10 {
  set zJournal2 [string replace $zJournal 24 27 [binary format I 256]]
  write_file test.db-journal $zJournal2
  execsql { 
    SELECT count(*) FROM t1;
    PRAGMA integrity_check
  }
} {0 ok}

do_test crash8-3.11 {
  set fd [open test.db-journal w]
  fconfigure $fd -translation binary 
  puts -nonewline $fd $zJournal
  close $fd
  execsql { 
    SELECT count(*) FROM t1;
    PRAGMA integrity_check

# 2008 April 17
#
# 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 implements regression tests for SQLite library. The focus
# of these tests is the journal mode pragma.
#
# $Id: jrnlmode.test,v 1.11 2009/01/10 16:15:09 danielk1977 Exp $

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

ifcapable {!pager_pragmas} {
  finish_test
  return

    expr {$journalsize>30000}
  } {1}
  do_test jrnlmode-5.19 {
    execsql COMMIT
    set sz [file size test.db-journal]
    expr {$sz>=$journalsize}
  } {1}

  # Test a size-limit of 0.
  #
  do_test jrnlmode-5.20 {
    execsql {
      PRAGMA journal_size_limit = 0;
      BEGIN;
      UPDATE t1 SET a = randomblob(1000);
    }
  } {0}
  do_test jrnlmode-5.21 {
    expr {[file size test.db-journal] > 1024}
  } {1}
  do_test jrnlmode-5.22 {
    execsql COMMIT
    list [file exists test.db-journal] [file size test.db-journal]
  } {1 0}
}

ifcapable pragma {
  do_test jrnlmode-6.1 {
    execsql {
      PRAGMA journal_mode = truncate;
      CREATE TABLE t4(a, b);

# This file attempts to check the behavior of the SQLite library in 
# an out-of-memory situation. When compiled with -DSQLITE_DEBUG=1, 
# the SQLite library accepts a special command (sqlite3_memdebug_fail N C)
# which causes the N-th malloc to fail.  This special feature is used
# to see what happens in the library if a malloc were to really fail
# due to an out-of-memory situation.
#
# $Id: malloc.test,v 1.73 2009/01/10 16:15:09 danielk1977 Exp $

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


# Only run these tests if memory debugging is turned on.
#

do_malloc_test 29 -sqlprep {
  CREATE TABLE t1(a TEXT, b TEXT);
} -sqlbody {
  INSERT INTO t1 VALUES(1, -234);
  INSERT INTO t1 SELECT * FROM t1 UNION ALL SELECT * FROM t1;
}

do_malloc_test 30 -tclprep {
  db eval {
    CREATE TABLE t1(x PRIMARY KEY);
    INSERT INTO t1 VALUES(randstr(500,500));
    INSERT INTO t1 VALUES(randstr(500,500));
    INSERT INTO t1 VALUES(randstr(500,500));
  }
  db close

  -- statement above. When requesting the pages, the content is loaded
  -- from the database file. The point of this test case is to test handling
  -- of malloc errors (including SQLITE_IOERR_NOMEM errors) when loading
  -- the content.
  SELECT * FROM t1 ORDER BY x;
}

# After committing a transaction in persistent-journal mode, if a journal
# size limit is configured SQLite may attempt to truncate the journal file.
# This test verifies the libraries response to a malloc() failure during
# this operation.
#
do_malloc_test 31 -sqlprep {
  PRAGMA journal_mode = persist;
  PRAGMA journal_size_limit = 1024;
  CREATE TABLE t1(a PRIMARY KEY, b);
} -sqlbody {
  INSERT INTO t1 VALUES(1, 2);
}

# Ensure that no file descriptors were leaked.
do_test malloc-99.X {
  catch {db close}
  set sqlite_open_file_count
} {0}

puts open-file-count=$sqlite_open_file_count
finish_test