volume_id: fat - accept empty FAT32 fsinfo signature

[elogind.git] / extras / volume_id / lib / fat.c

diff --git a/extras/volume_id/lib/fat.c b/extras/volume_id/lib/fat.c
index 2d98b65b50e7e2dca2bb51aaaaab061d2d7901c0..c0cfed82c008ccfd9d18c3a37f466f45ea7abbcf 100644 (file)
--- a/extras/volume_id/lib/fat.c
+++ b/extras/volume_id/lib/fat.c
@@ -411,7 +411,11 @@ magic:
 
 fat32:
        info("looking for FAT32\n");
-       /* FAT32 should have a valid signature in the fsinfo block */
+       /*
+        * FAT32 should have a valid signature in the fsinfo block,
+        * but also allow all bytes set to '\0', because some volumes
+        * do not set the signature at all.
+        */
        fsinfo_sect = le16_to_cpu(vs->type.fat32.fsinfo_sector);
        buf = volume_id_get_buffer(id, off + (fsinfo_sect * sector_size), 0x200);
        if (buf == NULL)
@@ -423,11 +427,13 @@ fat32:
        info("signature2: 0x%02x%02x%02x%02x\n",
             fsinfo->signature2[0], fsinfo->signature2[1],
             fsinfo->signature2[2], fsinfo->signature2[3]);
-       if (memcmp(fsinfo->signature1, "\x52\x52\x61\x41", 4) != 0)
+       if (memcmp(fsinfo->signature1, "\x52\x52\x61\x41", 4) != 0 &&
+           memcmp(fsinfo->signature1, "\x00\x00\x00\x00", 4) != 0)
                return -1;
-       if (memcmp(fsinfo->signature2, "\x72\x72\x41\x61", 4) != 0)
+       if (memcmp(fsinfo->signature2, "\x72\x72\x41\x61", 4) != 0 &&
+           memcmp(fsinfo->signature2, "\x00\x00\x00\x00", 4) != 0)
                return -1 ;
-       info("FAT32 signatures match\n");
+       info("FAT32 signatures ok\n");
 
        vs = (struct vfat_super_block *) volume_id_get_buffer(id, off, 0x200);
        if (vs == NULL)