[PULL,011/100] vvfat: always create . and .. entries at first and in that order

Commit Message

Kevin Wolf July 7, 2017, 5:07 p.m. UTC

From: Hervé Poussineau <[e-mail]>

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 <[e-mail]>
Signed-off-by: Kevin Wolf <[e-mail]>
---
 block/vvfat.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

Patch

diff --git a/block/vvfat.c b/block/vvfat.c
index 676cacb..0c6d0f4 100644
--- 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);