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Make sure we never try to "truncate" a file to a larger size. (CVS 4582)

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FossilOrigin-Name: 7d2f6a1d6c5ab89a3b65fbcaf172abf6d81e206b
This commit is contained in:
drh
2007-11-29 18:44:27 +00:00
parent ace03d1b3a
commit 7fe3f7e918
3 changed files with 22 additions and 9 deletions
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17
src/pager.c
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@@ -18,7 +18,7 @@
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.396 2007/11/28 16:19:56 drh Exp $
** @(#) $Id: pager.c,v 1.397 2007/11/29 18:44:27 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
@@ -1646,11 +1646,24 @@ static void pager_truncate_cache(Pager *pPager);
/*
** Truncate the main file of the given pager to the number of pages
** indicated. Also truncate the cached representation of the file.
**
** Might might be the case that the file on disk is smaller than nPage.
** This can happen, for example, if we are in the middle of a transaction
** which has extended the file size and the new pages are still all held
** in cache, then an INSERT or UPDATE does a statement rollback. Some
** operating system implementations can get confused if you try to
** truncate a file to some size that is larger than it currently is,
** so detect this case and do not do the truncation.
*/
static int pager_truncate(Pager *pPager, int nPage){
int rc = SQLITE_OK;
if( pPager->state>=PAGER_EXCLUSIVE && pPager->fd->pMethods ){
rc = sqlite3OsTruncate(pPager->fd, pPager->pageSize*(i64)nPage);
i64 currentSize, newSize;
rc = sqlite3OsFileSize(pPager->fd, &currentSize);
newSize = pPager->pageSize*(i64)nPage;
if( rc==SQLITE_OK && currentSize>newSize ){
rc = sqlite3OsTruncate(pPager->fd, newSize);
}
}
if( rc==SQLITE_OK ){
pPager->dbSize = nPage;