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When opening a zero-size database on unix, write one byte into the file before

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interrogating the inode number.  This works around issues with msdos
filesystems mounted on OS-X.  Ticket #3260. (CVS 5504)

FossilOrigin-Name: a480a8845fb3b49967de0790b30e6250c824b9be
This commit is contained in:
drh
2008-07-30 17:28:04 +00:00
parent da0e768be2
commit 5462624dc4
5 changed files with 51 additions and 15 deletions
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30
src/os_unix.c
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@@ -12,7 +12,7 @@
**
** This file contains code that is specific to Unix systems.
**
** $Id: os_unix.c,v 1.194 2008/07/30 15:27:54 drh Exp $
** $Id: os_unix.c,v 1.195 2008/07/30 17:28:04 drh Exp $
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX /* This file is used on unix only */
@@ -674,6 +674,24 @@ static int findLockInfo(
return SQLITE_IOERR;
}
/* On OS X on an msdos filesystem, the inode number is reported
** incorrectly for zero-size files. See ticket #3260. To work
** around this problem (we consider it a bug in OS X, not SQLite)
** we always increase the file size to 1 by writing a single byte
** prior to accessing the inode number. The one byte written is
** an ASCII 'S' character which also happens to be the first byte
** in the header of every SQLite database. In this way, if there
** is a race condition such that another thread has already populated
** the first page of the database, no damage is done.
*/
if( statbuf.st_size==0 ){
write(fd, "S", 1);
rc = fstat(fd, &statbuf);
if( rc!=0 ){
return SQLITE_IOERR;
}
}
memset(&key1, 0, sizeof(key1));
key1.dev = statbuf.st_dev;
key1.ino = statbuf.st_ino;
@@ -1092,6 +1110,16 @@ static int unixFileSize(sqlite3_file *id, i64 *pSize){
return SQLITE_IOERR_FSTAT;
}
*pSize = buf.st_size;
/* When opening a zero-size database, the findLockInfo() procedure
** writes a single byte into that file in order to work around a bug
** in the OS-X msdos filesystem. In order to avoid problems with upper
** layers, we need to report this file size as zero even though it is
** really 1. Ticket #3260.
*/
if( *pSize==1 ) *pSize = 0;
return SQLITE_OK;
}