vvfat: always create . and .. entries at first and in that order

readdir() doesn't always return . and .. entries at first and in that order.
This leads to not creating them at first in the directory, which raises some
errors on file system checking utilities like MS-DOS Scandisk.

Specification: "FAT: General overview of on-disk format" v1.03, page 25

Fixes: https://bugs.launchpad.net/qemu/+bug/1599539
Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block/vvfat.c b/block/vvfat.c
index 676cacb76b21ec55cfb09b7b7b9ea704be7d9527..0c6d0f407f4c3cab9c87c49260e09ae1b1eb6a95 100644 (file)
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -727,6 +727,12 @@ static int read_directory(BDRVVVFATState* s, int mapping_index)
     i = mapping->info.dir.first_dir_index =
             first_cluster == 0 ? 0 : s->directory.next;
 
+    if (first_cluster != 0) {
+        /* create the top entries of a subdirectory */
+        (void)create_short_and_long_name(s, i, ".", 1);
+        (void)create_short_and_long_name(s, i, "..", 1);
+    }
+
     /* actually read the directory, and allocate the mappings */
     while((entry=readdir(dir))) {
         unsigned int length=strlen(dirname)+2+strlen(entry->d_name);
@@ -748,8 +754,11 @@ static int read_directory(BDRVVVFATState* s, int mapping_index)
         }
 
         /* create directory entry for this file */
-        direntry=create_short_and_long_name(s, i, entry->d_name,
-                is_dot || is_dotdot);
+        if (!is_dot && !is_dotdot) {
+            direntry = create_short_and_long_name(s, i, entry->d_name, 0);
+        } else {
+            direntry = array_get(&(s->directory), is_dot ? i : i + 1);
+        }
         direntry->attributes=(S_ISDIR(st.st_mode)?0x10:0x20);
         direntry->reserved[0]=direntry->reserved[1]=0;
         direntry->ctime=fat_datetime(st.st_ctime,1);