| Message ID | 1461843366-27217-2-git-send-email-kwolf@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 28 April 2016 at 12:36, Kevin Wolf <kwolf@redhat.com> wrote: > Commit d5941dd made the volume name configurable, but it didn't consider > that the rw code compares the volume name string to assert that the > first directory entry is the volume name. This made vvfat crash in rw > mode. So you couldn't use this for writing at all, and we broke this a year ago, and nobody complained til now? Shows how little vvfat gets used... thanks -- PMM
Kevin Wolf <kwolf@redhat.com> writes: > Commit d5941dd made the volume name configurable, but it didn't consider > that the rw code compares the volume name string to assert that the > first directory entry is the volume name. This made vvfat crash in rw > mode. > > This fixes the assertion to compare with the configured volume name > instead of a literal string. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > block/vvfat.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/block/vvfat.c b/block/vvfat.c > index 6b85314..ff3df35 100644 > --- a/block/vvfat.c > +++ b/block/vvfat.c > @@ -2283,12 +2283,17 @@ DLOG(fprintf(stderr, "commit_direntries for %s, parent_mapping_index %d\n", mapp > factor * (old_cluster_count - new_cluster_count)); > > for (c = first_cluster; !fat_eof(s, c); c = modified_fat_get(s, c)) { > + direntry_t *first_direntry; > void* direntry = array_get(&(s->directory), current_dir_index); > int ret = vvfat_read(s->bs, cluster2sector(s, c), direntry, > s->sectors_per_cluster); > if (ret) > return ret; > - assert(!strncmp(s->directory.pointer, "QEMU", 4)); Typing all of "QEMU VVAT" a third time was clearly too much. > + > + /* The first directory entry on the filesystem is the volume name */ > + first_direntry = (direntry_t*) s->directory.pointer; I'd ask to correct the spacing to (direntry_t *)s if the spacing wasn't similarly off all over this file. > + assert(!memcmp(first_direntry->name, s->volume_label, 11)); > + > current_dir_index += factor; > } Might want to to assert is_volume_label(), too. But even if you want to, let's not delay the fix for that. Reviewed-by: Markus Armbruster <armbru@redhat.com>
On Thu, Apr 28, 2016 at 01:36:05PM +0200, Kevin Wolf wrote: > Commit d5941dd made the volume name configurable, but it didn't consider > that the rw code compares the volume name string to assert that the > first directory entry is the volume name. This made vvfat crash in rw > mode. > > This fixes the assertion to compare with the configured volume name > instead of a literal string. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > block/vvfat.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) I just noticed that Wolfgang's original patch got rid of the default "QEMU VVFAT " volume label. It now defaults to all spaces but I'm not sure if this causes any problems... Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/block/vvfat.c b/block/vvfat.c index 6b85314..ff3df35 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -2283,12 +2283,17 @@ DLOG(fprintf(stderr, "commit_direntries for %s, parent_mapping_index %d\n", mapp factor * (old_cluster_count - new_cluster_count)); for (c = first_cluster; !fat_eof(s, c); c = modified_fat_get(s, c)) { + direntry_t *first_direntry; void* direntry = array_get(&(s->directory), current_dir_index); int ret = vvfat_read(s->bs, cluster2sector(s, c), direntry, s->sectors_per_cluster); if (ret) return ret; - assert(!strncmp(s->directory.pointer, "QEMU", 4)); + + /* The first directory entry on the filesystem is the volume name */ + first_direntry = (direntry_t*) s->directory.pointer; + assert(!memcmp(first_direntry->name, s->volume_label, 11)); + current_dir_index += factor; }
Commit d5941dd made the volume name configurable, but it didn't consider that the rw code compares the volume name string to assert that the first directory entry is the volume name. This made vvfat crash in rw mode. This fixes the assertion to compare with the configured volume name instead of a literal string. Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block/vvfat.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)