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

Ensure a database file is not truncated without an exclusive lock.

Browse Source 
Fix for ticket #1114. (CVS 2332)

FossilOrigin-Name: dcbc983355d3207615b52b0724405a024a1a5955
This commit is contained in:
danielk1977
2005-02-15 03:38:05 +00:00
parent 3c407374fc
commit 1722181328
3 changed files with 54 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files

86
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 1.189 2005/02/15 02:54:15 danielk1977 Exp $
** @(#) $Id: pager.c,v 1.190 2005/02/15 03:38:06 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
@@ -1137,6 +1137,7 @@ static int pager_reload_cache(Pager *pPager){
** indicated.
*/
static int pager_truncate(Pager *pPager, int nPage){
assert( pPager->state>=PAGER_EXCLUSIVE );
return sqlite3OsTruncate(&pPager->fd, pPager->pageSize*(i64)nPage);
}
@@ -1256,7 +1257,8 @@ static int pager_playback(Pager *pPager){
/* If this is the first header read from the journal, truncate the
** database file back to it's original size.
*/
if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
if( pPager->state>=PAGER_EXCLUSIVE &&
pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
assert( pPager->origDbSize==0 || pPager->origDbSize==mxPg );
rc = pager_truncate(pPager, mxPg);
if( rc!=SQLITE_OK ){
@@ -1354,10 +1356,11 @@ static int pager_stmt_playback(Pager *pPager){
hdrOff = szJ;
}
/* Truncate the database back to its original size.
*/
rc = pager_truncate(pPager, pPager->stmtSize);
if( pPager->state>=PAGER_EXCLUSIVE ){
rc = pager_truncate(pPager, pPager->stmtSize);
}
pPager->dbSize = pPager->stmtSize;
/* Figure out how many records are in the statement journal.
@@ -1804,6 +1807,37 @@ static void memoryTruncate(Pager *pPager){
#define memoryTruncate(p)
#endif
/*
** Try to obtain a lock on a file. Invoke the busy callback if the lock
** is currently not available. Repeate until the busy callback returns
** false or until the lock succeeds.
**
** Return SQLITE_OK on success and an error code if we cannot obtain
** the lock.
*/
static int pager_wait_on_lock(Pager *pPager, int locktype){
int rc;
assert( PAGER_SHARED==SHARED_LOCK );
assert( PAGER_RESERVED==RESERVED_LOCK );
assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );
if( pPager->state>=locktype ){
rc = SQLITE_OK;
}else{
int busy = 1;
do {
rc = sqlite3OsLock(&pPager->fd, locktype);
}while( rc==SQLITE_BUSY &&
pPager->pBusyHandler &&
pPager->pBusyHandler->xFunc &&
pPager->pBusyHandler->xFunc(pPager->pBusyHandler->pArg, busy++)
);
if( rc==SQLITE_OK ){
pPager->state = locktype;
}
}
return rc;
}
/*
** Truncate the file to the number of pages specified.
*/
@@ -1826,6 +1860,13 @@ int sqlite3pager_truncate(Pager *pPager, Pgno nPage){
if( rc!=SQLITE_OK ){
return rc;
}
/* Get an exclusive lock on the database before truncating. */
rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
if( rc!=SQLITE_OK ){
return rc;
}
rc = pager_truncate(pPager, nPage);
if( rc==SQLITE_OK ){
pPager->dbSize = nPage;
@@ -2057,37 +2098,6 @@ static int syncJournal(Pager *pPager){
return rc;
}
/*
** Try to obtain a lock on a file. Invoke the busy callback if the lock
** is currently not available. Repeate until the busy callback returns
** false or until the lock succeeds.
**
** Return SQLITE_OK on success and an error code if we cannot obtain
** the lock.
*/
static int pager_wait_on_lock(Pager *pPager, int locktype){
int rc;
assert( PAGER_SHARED==SHARED_LOCK );
assert( PAGER_RESERVED==RESERVED_LOCK );
assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );
if( pPager->state>=locktype ){
rc = SQLITE_OK;
}else{
int busy = 1;
do {
rc = sqlite3OsLock(&pPager->fd, locktype);
}while( rc==SQLITE_BUSY &&
pPager->pBusyHandler &&
pPager->pBusyHandler->xFunc &&
pPager->pBusyHandler->xFunc(pPager->pBusyHandler->pArg, busy++)
);
if( rc==SQLITE_OK ){
pPager->state = locktype;
}
}
return rc;
}
/*
** Given a list of pages (connected by the PgHdr.pDirty pointer) write
** every one of those pages out to the database file and mark them all
@@ -3072,13 +3082,11 @@ int sqlite3pager_rollback(Pager *pPager){
return pager_errcode(pPager);
}
if( pPager->state==PAGER_RESERVED ){
int rc2, rc3;
int rc2;
rc = pager_reload_cache(pPager);
rc2 = pager_truncate(pPager, pPager->origDbSize);
rc3 = pager_unwritelock(pPager);
rc2 = pager_unwritelock(pPager);
if( rc==SQLITE_OK ){
rc = rc2;
if( rc3 ) rc = rc3;
}
}else{
rc = pager_playback(pPager);