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Change the xShmSize() implementation in os_unix.c so that it will only

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increase and never decrease the size of a shared-memory segment.

FossilOrigin-Name: 149d2ae4a6fe2f86822f286d2a7092c51bec7ebb
This commit is contained in:
drh
2010-05-13 08:33:35 +00:00
parent bd50ddeb42
commit a925fd256b
3 changed files with 34 additions and 15 deletions
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23
src/os_unix.c
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@@ -3957,16 +3957,25 @@ static int unixShmSize(
int rc = SQLITE_OK;
struct stat sStat;
if( reqSize>=0 ){
/* On a query, this loop runs once. When reqSize>=0, the loop potentially
** runs twice, except if the actual size is already greater than or equal
** to the requested size, reqSize is set to -1 on the first iteration and
** the loop only runs once.
*/
while( 1 ){
if( fstat(pFile->h, &sStat)==0 ){
*pNewSize = (int)sStat.st_size;
if( reqSize>=0 && reqSize<=(int)sStat.st_size ) break;
}else{
*pNewSize = 0;
rc = SQLITE_IOERR;
break;
}
if( reqSize<0 ) break;
reqSize = (reqSize + SQLITE_UNIX_SHM_INCR - 1)/SQLITE_UNIX_SHM_INCR;
reqSize *= SQLITE_UNIX_SHM_INCR;
rc = ftruncate(pFile->h, reqSize);
}
if( fstat(pFile->h, &sStat)==0 ){
*pNewSize = (int)sStat.st_size;
}else{
*pNewSize = 0;
rc = SQLITE_IOERR;
reqSize = -1;
}
return rc;
}