database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-07 02:42:48 +03:00
Code Activity

Fix a couple of potential corruption problems in pager.c. (CVS 6143)

Browse Source 
FossilOrigin-Name: 5a39525ba3e65f1c6df3cf23fbfb57f6a0bf4b62
This commit is contained in:
danielk1977
2009-01-08 17:50:45 +00:00
parent 4fd18c4b31
commit 112f752be8
4 changed files with 159 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
src/pager.c
View File

@@ -18,7 +18,7 @@
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.541 2009/01/08 15:24:02 drh Exp $
** @(#) $Id: pager.c,v 1.542 2009/01/08 17:50:46 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
@@ -580,7 +580,7 @@ static int readMasterJournal(sqlite3_file *pJrnl, char *zMaster, u32 nMaster){
** 2000 2048
**
*/
static void seekJournalHdr(Pager *pPager){
static i64 journalHdrOffset(Pager *pPager){
i64 offset = 0;
i64 c = pPager->journalOff;
if( c ){
@@ -589,7 +589,10 @@ static void seekJournalHdr(Pager *pPager){
assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
assert( offset>=c );
assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
pPager->journalOff = offset;
return offset;
}
static void seekJournalHdr(Pager *pPager){
pPager->journalOff = journalHdrOffset(pPager);
}
/*
@@ -2487,6 +2490,35 @@ static int syncJournal(Pager *pPager){
assert( pPager->journalOpen );
if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
i64 jrnlOff = journalHdrOffset(pPager);
u8 zMagic[8];
/* This block deals with an obscure problem. If the last connection
** that wrote to this database was operating in persistent-journal
** mode, then the journal file may at this point actually be larger
** than Pager.journalOff bytes. If the next thing in the journal
** file happens to be a journal-header (written as part of the
** previous connections transaction), and a crash or power-failure
** occurs after nRec is updated but before this connection writes
** anything else to the journal file (or commits/rolls back its
** transaction), then SQLite may become confused when doing the
** hot-journal rollback following recovery. It may roll back all
** of this connections data, then proceed to rolling back the old,
** out-of-date data that follows it. Database corruption.
**
** To work around this, if the journal file does appear to contain
** a valid header following Pager.journalOff, then write a 0x00
** byte to the start of it to prevent it from being recognized.
*/
rc = sqlite3OsRead(pPager->jfd, zMagic, 8, jrnlOff);
if( rc==SQLITE_OK && 0==memcmp(zMagic, aJournalMagic, 8) ){
static const u8 zerobyte = 0;
rc = sqlite3OsWrite(pPager->jfd, &zerobyte, 1, jrnlOff);
}
if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
return rc;
}
/* Write the nRec value into the journal file header. If in
** full-synchronous mode, sync the journal first. This ensures that
** all data has really hit the disk before nRec is updated to mark
@@ -2498,7 +2530,6 @@ static int syncJournal(Pager *pPager){
** is populated with 0xFFFFFFFF when the journal header is written
** and never needs to be updated.
*/
i64 jrnlOff;
if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
IOTRACE(("JSYNC %p\n", pPager))
@@ -2879,8 +2910,10 @@ static int pagerSharedLock(Pager *pPager){
pPager->journalHdr = 0;
/* Playback and delete the journal. Drop the database write
** lock and reacquire the read lock.
** lock and reacquire the read lock. Purge the cache before
** playing back the hot-journal so that we don't end up with
*/
sqlite3PcacheClear(pPager->pPCache);
rc = pager_playback(pPager, 1);
if( rc!=SQLITE_OK ){
rc = pager_error(pPager, rc);