vvfat: Fix volume name assertion

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>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 6 insertions, 1 deletions

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;
     }