Date: Tue, 16 Jan 2001 12:16:12 -0800 (PST) From: semenu@FreeBSD.org To: freebsd-gnats-submit@FreeBSD.org Subject: kern/24393: Patch to msdosfs to handle a kind of incorrect filesystems Message-ID: <200101162016.f0GKGCU11053@freefall.freebsd.org>
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>Number: 24393
>Category: kern
>Synopsis: Patch to msdosfs to handle a kind of incorrect filesystems
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Jan 16 12:20:04 PST 2001
>Closed-Date:
>Last-Modified:
>Originator: Semen A. Ustimenko
>Release: 4.2-RELEASE
>Organization:
>Environment:
FreeBSD dev.the.net 4.2-RELEASE FreeBSD 4.2-RELEASE #3: Tue Dec 12 15:23:17 GMT+6 2000 root@default.the.net:/usr/src/sys/compile/DEFAULT i386
>Description:
There are sometimes a FAT filesystems not handled correctly by msdosfs
driver, but handled by mtools and other OSes. The problem is that
msdosfs assume . entry in directory have cluster number set to real
directory cluster number. But sometimes cluster number for . entry is
set to 0, and msdosfs behaves wrong with such filesystems.
>How-To-Repeat:
Take a FAT12 formatted diskette image from vmware2 distribution
(vmware-distrib/lib/floppies/windows.flp):
without patch:
# ls -lR /floppy
ls: win2k: directory causes a cycle
ls: win9x: directory causes a cycle
ls: winnt: directory causes a cycle
total 850
-rwxr-xr-x 1 root wheel 870002 Nov 1 17:36 VMwareTools.exe
drwxr-xr-x 1 root wheel 0 Nov 1 17:36 win2k
drwxr-xr-x 1 root wheel 0 Nov 1 17:36 win9x
drwxr-xr-x 1 root wheel 0 Nov 1 17:36 winnt
with patch:
# ls -lR /floppy
total 852
-rwxr-xr-x 1 root wheel 870002 Nov 1 17:36 VMwareTools.exe
drwxr-xr-x 1 root wheel 512 Nov 1 17:36 win2k
drwxr-xr-x 1 root wheel 512 Nov 1 17:36 win9x
drwxr-xr-x 1 root wheel 512 Nov 1 17:36 winnt
/floppy/win2k:
total 28
-rwxr-xr-x 1 root wheel 18432 Nov 1 17:36 vmx_fb.dll
-rwxr-xr-x 1 root wheel 2274 Nov 1 17:36 vmx_svga.inf
-rwxr-xr-x 1 root wheel 7440 Nov 1 17:36 vmx_svga.sys
/floppy/win9x:
total 25
-rwxr-xr-x 1 root wheel 17136 Nov 1 17:36 VMX_SVGA.DRV
-rwxr-xr-x 1 root wheel 5991 Nov 1 17:36 VMX_SVGA.vxd
-rwxr-xr-x 1 root wheel 1669 Nov 1 17:36 vmx_svga.inf
/floppy/winnt:
total 38
-rwxr-xr-x 1 root wheel 17408 Nov 1 17:36 vmx_fb.dll
-rwxr-xr-x 1 root wheel 13637 Nov 1 17:36 vmx_svga.inf
-rwxr-xr-x 1 root wheel 7440 Nov 1 17:36 vmx_svga.sys
>Fix:
Use following patch:
Index: src/sys/msdosfs/msdosfs_denode.c
===================================================================
RCS file: /usr/home/ncvs/src/sys/msdosfs/msdosfs_denode.c,v
retrieving revision 1.47.2.1
diff -c -r1.47.2.1 msdosfs_denode.c
*** src/sys/msdosfs/msdosfs_denode.c 2000/07/08 14:34:27 1.47.2.1
--- src/sys/msdosfs/msdosfs_denode.c 2001/01/16 19:30:13
***************
*** 356,361 ****
--- 356,371 ----
*/
u_long size;
+ /*
+ * XXX Sometimes, there arrives that . entry have cluster
+ * number 0, when it shouldn't. Use real cluster number
+ * instead of what is written in directory entry.
+ */
+ if ((diroffset == 0) && (ldep->de_StartCluster != dirclust)) {
+ printf("deget(): . entry at clust %ld != %ld\n", dirclust, ldep->de_StartCluster);
+ ldep->de_StartCluster = dirclust;
+ }
+
nvp->v_type = VDIR;
if (ldep->de_StartCluster != MSDOSFSROOT) {
error = pcbmap(ldep, 0xffff, 0, &size, 0);
>Release-Note:
>Audit-Trail:
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