[Libcdio-devel] [PATCH] Fix invalid/bad directory errors with openSUSE Leap 15.0 ISO

[Pete Batard]

Hi,

Taking in all the good advice from the earlier discussion, I am 
proposing to apply the attached set of patches to address the issue of 
processing openSUSE Leap, and other non specs-compliant ISOs, without 
bailing out or reporting warnings.

This basically alters from_733() to remove all warnings and return the 
little endian value always, and use this call, instead of 
from_733_with_err(), in iso9660_fs.c.

For good measure, from_723() is also altered in the same fashion, and a 
new from_723_with_err() is introduced, so we may use this in place where 
we may want to detect LE vs BE mismatch.

I have tested this patch against the problematic openSUSE Leap 15.0 ISO 
and found that both isofile and isolist worked as expected. I have only 
tested on a little-endian arch however.

I should be able to push these patches to mainline, provided I receive a 
green light from Rocky (and provided Thomas doesn't have objections 
about this proposal).

Regards,

/Pete


On 2018.05.26 23:00, Thomas Schmitt wrote:
> Hi,
>
> i wrote:
>
> >   uint8_t *u;
> >   u = (uint8_t *) p;
> >   return (u[0] | (u[1] << 8) | (u[2] << 16) | (u[3] << 24));
>
> not enough "&":
>
>    u = (uint8_t *) &p;
>
> I should have compiled first before sending mail.
>
>
> Have a nice day :)
>
> Thomas

From a4155f014c640e6896a41205a0f997be8db33808 Mon Sep 17 00:00:00 2001
From: Pete Batard <address@hidden>
Date: Sun, 27 May 2018 22:27:27 +0100
Subject: [PATCH 1/2] Set from_723 and from_733 to return the little-endian
 value always

* And silence the warning in case of little-endian and big-endian mismatch
* Also introduce a from_723_with_err() that can be used to report mismatch
  if needed
---
 include/cdio/bytesex.h | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/include/cdio/bytesex.h b/include/cdio/bytesex.h
index 0ec92463..c66ed809 100644
--- a/include/cdio/bytesex.h
+++ b/include/cdio/bytesex.h
@@ -171,9 +171,20 @@ to_723(uint16_t i)
 static CDIO_INLINE uint16_t
 from_723 (uint32_t p)
 {
-  if (uint32_swap_le_be (p) != p)
-    cdio_warn ("from_723: broken byte order");
+  uint8_t *u = (uint8_t *) &p;
+  /* Return the little-endian part always, to handle non-specs-compliant 
images */
+  return (u[0] | (u[1] << 8));
+}
 
+static CDIO_INLINE uint16_t
+from_723_with_err (uint32_t p, bool *err)
+{
+  if (uint32_swap_le_be (p) != p) {
+    cdio_warn ("from_723: broken byte order");
+    *err = true;
+  } else {
+    *err = false;
+  }
   return (0xFFFF & p);
 }
 
@@ -200,10 +211,9 @@ to_733(uint32_t i)
 static CDIO_INLINE uint32_t
 from_733 (uint64_t p)
 {
-  if (uint64_swap_le_be (p) != p)
-    cdio_warn ("from_733: broken byte order");
-
-  return (UINT32_C(0xFFFFFFFF) & p);
+  uint8_t *u = (uint8_t *) &p;
+  /* Return the little-endian part always, to handle non-specs-compliant 
images */
+  return (u[0] | (u[1] << 8) | (u[2] << 16) | (u[3] << 24));
 }
 
 static CDIO_INLINE uint32_t
-- 
2.17.0.windows.1

From 93a3fdc55c704f3f9bb20ab15ca8d94330f4ef7f Mon Sep 17 00:00:00 2001
From: Pete Batard <address@hidden>
Date: Sun, 27 May 2018 22:30:04 +0100
Subject: [PATCH 2/2] Switch to using the more relaxed from_733 in
 _iso9660_dir_to_statbuf

* Done so that libcdio doesn't bail out when processing non-compliant
  ISOs such as openSUSE Leap 15.0
---
 lib/iso9660/iso9660_fs.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/lib/iso9660/iso9660_fs.c b/lib/iso9660/iso9660_fs.c
index 85ad2736..33f47711 100644
--- a/lib/iso9660/iso9660_fs.c
+++ b/lib/iso9660/iso9660_fs.c
@@ -784,7 +784,6 @@ _iso9660_dir_to_statbuf (iso9660_dir_t *p_iso9660_dir, 
bool_3way_t b_xa,
   iso711_t i_fname;
   unsigned int stat_len;
   iso9660_stat_t *p_stat = NULL;
-  bool err;
 
   if (!dir_len) return NULL;
 
@@ -801,16 +800,8 @@ _iso9660_dir_to_statbuf (iso9660_dir_t *p_iso9660_dir, 
bool_3way_t b_xa,
     }
   p_stat->type    = (p_iso9660_dir->file_flags & ISO_DIRECTORY)
     ? _STAT_DIR : _STAT_FILE;
-  p_stat->lsn     = from_733_with_err (p_iso9660_dir->extent, &err);
-  if (err) {
-    free(p_stat);
-    return NULL;
-  }
-  p_stat->size    = from_733_with_err (p_iso9660_dir->size, &err);
-  if (err) {
-    free(p_stat);
-    return NULL;
-  }
+  p_stat->lsn     = from_733 (p_iso9660_dir->extent);
+  p_stat->size    = from_733 (p_iso9660_dir->size);
   p_stat->secsize = _cdio_len2blocks (p_stat->size, ISO_BLOCKSIZE);
   p_stat->rr.b3_rock = dunno; /*FIXME should do based on mask */
   p_stat->b_xa    = false;
-- 
2.17.0.windows.1