[Libcdio-devel] [PATCH] fix file offset out of bounds when reading multiple UDF files

[Pete Batard]

If you followed the instructions from the previous e-mail and tried to 
run the extract sample against the Windows 8 preview UDF, this is what 
you get:

----------------------------------------------------------------------
# ./extract 
/mnt/extra/WindowsDeveloperPreview-64bit-English-Developer.iso 
/mnt/data/test/
--DEBUG: source name 
/mnt/extra/WindowsDeveloperPreview-64bit-English-Developer.iso is not 
recognized as a TOC file
--DEBUG: opened source...
   INFO: Image not recognized as either version 5.0 or version 
5.5.x-6.x type NRG
--DEBUG: closed source...
--DEBUG: source name 
/mnt/extra/WindowsDeveloperPreview-64bit-English-Developer.iso is not 
recognized as a NRG image
--DEBUG: opened source...
Volume id: UDF Volume
Volume set id: UDF Volume
Partition number: 2989
Extracting: /mnt/data/test//
Extracting: /mnt/data/test//autorun.inf
Extracting: /mnt/data/test//boot
Extracting: /mnt/data/test//boot/
Extracting: /mnt/data/test//boot/bcd
Extracting: /mnt/data/test//boot/boot.sdi
File offset out of bounds
  Error reading UDF file /boot/boot.sdi
--DEBUG: closed source...
----------------------------------------------------------------------

Analysis shows that the issue is due to the p_udf->i_position attribute 
not being reset when accessing files sequentially (i.e. on subsequent 
file access the UDF file offset will be set close to the size of the 
previous file instead of zero) which eventually results in an out of 
bound offset. The attached patch fixes this.

Again, I'll be holding on pushing this patch for a day or two unless I 
get a green light.

Regards,

/Pete

>From fb55e37d3d832ad2004bb020a724d243e338235f Mon Sep 17 00:00:00 2001
From: Pete Batard <address@hidden>
Date: Fri, 20 Jan 2012 16:43:57 +0000
Subject: [PATCH] Fix offset not being reset for sequential UDF file access

---
 lib/udf/udf_fs.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/lib/udf/udf_fs.c b/lib/udf/udf_fs.c
index e5900c7..dcd6e53 100644
--- a/lib/udf/udf_fs.c
+++ b/lib/udf/udf_fs.c
@@ -236,7 +236,10 @@ udf_fopen(udf_dirent_t *p_udf_root, const char *psz_name)
   if (p_udf_root) {
     char tokenline[udf_MAX_PATHLEN];
     char *psz_token;
-    
+
+    /* file position must be reset when accessing a new file */
+    p_udf_root->p_udf->i_position = 0;
+
     strncpy(tokenline, psz_name, udf_MAX_PATHLEN);
     psz_token = strtok(tokenline, udf_PATH_DELIMITERS);
     if (psz_token) {
@@ -612,7 +615,10 @@ udf_readdir(udf_dirent_t *p_udf_dirent)
     return NULL;
   }
 
+  /* file position must be reset when accessing a new file */
   p_udf = p_udf_dirent->p_udf;
+  p_udf->i_position = 0;
+
   if (p_udf_dirent->fid) { 
     /* advance to next File Identifier Descriptor */
     /* FIXME: need to advance file entry (fe) as well.  */
-- 
1.7.8.msysgit.0