libarchive: Backport patch from upstream (rev 2516)

Fix Issue 100:  Allow a zero for the Type M Path Table Location, since
WinISO (and probably other programs) set it this way.

http://code.google.com/p/libarchive/source/detail?r=2516

Upstream-Status: Backport

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>

diff --git a/libarchive/archive_read_support_format_iso9660.c b/libarchive/archive_read_support_format_iso9660.c
index 0c640c8..fdef3fb 100644
--- a/libarchive/archive_read_support_format_iso9660.c
+++ b/libarchive/archive_read_support_format_iso9660.c
@@ -714,11 +714,13 @@ isSVD(struct iso9660 *iso9660, const unsigned char *h)
 	if (location <= SYSTEM_AREA_BLOCK+2 || location >= volume_block)
 		return (0);
 
-	/* Location of Occurrence of Type M Path Table must be
-	 * available location,
+	/* The Type M Path Table must be at a valid location (WinISO
+	 * and probably other programs omit this, so we allow zero)
+	 *
 	 * > SYSTEM_AREA_BLOCK(16) + 2 and < Volume Space Size. */
 	location = archive_be32dec(h+SVD_type_M_path_table_offset);
-	if (location <= SYSTEM_AREA_BLOCK+2 || location >= volume_block)
+	if ((location > 0 && location <= SYSTEM_AREA_BLOCK+2)
+	    || location >= volume_block)
 		return (0);
 
 	/* Read Root Directory Record in Volume Descriptor. */
@@ -790,7 +792,8 @@ isEVD(struct iso9660 *iso9660, const unsigned char *h)
 	 * available location,
 	 * > SYSTEM_AREA_BLOCK(16) + 2 and < Volume Space Size. */
 	location = archive_be32dec(h+PVD_type_m_path_table_offset);
-	if (location <= SYSTEM_AREA_BLOCK+2 || location >= volume_block)
+	if ((location > 0 && location <= SYSTEM_AREA_BLOCK+2)
+	    || location >= volume_block)
 		return (0);
 
 	/* Reserved field must be 0. */
@@ -865,11 +868,14 @@ isPVD(struct iso9660 *iso9660, const unsigned char *h)
 	if (location <= SYSTEM_AREA_BLOCK+2 || location >= volume_block)
 		return (0);
 
-	/* Location of Occurrence of Type M Path Table must be
-	 * available location,
+	/* The Type M Path Table must also be at a valid location
+	 * (although ECMA 119 requires a Type M Path Table, WinISO and
+	 * probably other programs omit it, so we permit a zero here)
+	 *
 	 * > SYSTEM_AREA_BLOCK(16) + 2 and < Volume Space Size. */
 	location = archive_be32dec(h+PVD_type_m_path_table_offset);
-	if (location <= SYSTEM_AREA_BLOCK+2 || location >= volume_block)
+	if ((location > 0 && location <= SYSTEM_AREA_BLOCK+2)
+	    || location >= volume_block)
 		return (0);
 
 	/* Reserved field must be 0. */
-- 
1.7.1