[SCM] libav/experimental: Check the index validity more thoroughly for the c93 probe function. In particular, check that length of the first index entries is not 0 since that is interpreted "end of file" and makes no sense in the very first entries.

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit 9f449d57c7d6e0b54335eaddad69ec773c31a037
Author: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
Date:   Mon Sep 14 20:01:32 2009 +0000

    Check the index validity more thoroughly for the c93 probe function.
    In particular, check that length of the first index entries is not 0 since
    that is interpreted "end of file" and makes no sense in the very first entries.
    
    Originally committed as revision 19843 to svn://svn.ffmpeg.org/ffmpeg/trunk

diff --git a/libavformat/c93.c b/libavformat/c93.c
index 11a0314..e829e39 100644
--- a/libavformat/c93.c
+++ b/libavformat/c93.c
@@ -21,6 +21,7 @@
 
 #include "avformat.h"
 #include "voc.h"
+#include "libavutil/intreadwrite.h"
 
 typedef struct {
     uint16_t index;
@@ -43,13 +44,16 @@ typedef struct {
 
 static int probe(AVProbeData *p)
 {
-    if (p->buf[0] == 0x01 && p->buf[1] == 0x00 &&
-        p->buf[4] == 0x01 + p->buf[2] &&
-        p->buf[8] == p->buf[4] + p->buf[6] &&
-        p->buf[12] == p->buf[8] + p->buf[10])
-        return AVPROBE_SCORE_MAX;
-
-    return 0;
+    int i;
+    int index = 1;
+    if (p->buf_size < 16)
+        return 0;
+    for (i = 0; i < 16; i += 4) {
+        if (AV_RL16(p->buf + i) != index || !p->buf[i + 2] || !p->buf[i + 3])
+            return 0;
+        index += p->buf[i + 2];
+    }
+    return AVPROBE_SCORE_MAX;
 }
 
 static int read_header(AVFormatContext *s,

-- 
Libav/FFmpeg packaging