[FFmpeg-devel] [PATCH] rmdec.c: correctly skip indexes

[Ronald S. Bultje]

Hi,

On Mon, Mar 9, 2009 at 6:14 PM, Reimar D?ffinger
<Reimar.Doeffinger at gmx.de> wrote:
> The indendation is off. Also I think moving the 20 to the other side
> obfuscates things. Consider of maybe this is better:
[..]

Almost copied, I kept the n_pkts variable because I'd like to print it
in the log msg if output is wrong, and renamed the fixed_len variable
to something more sensible (expected_len).

See attached, thanks for the comments. :-).

Ronald
-------------- next part --------------
Index: ffmpeg-svn/libavformat/rmdec.c
===================================================================
--- ffmpeg-svn.orig/libavformat/rmdec.c	2009-03-09 23:54:17.000000000 -0400
+++ ffmpeg-svn/libavformat/rmdec.c	2009-03-09 23:55:56.000000000 -0400
@@ -440,7 +440,19 @@
             state= (state<<8) + get_byte(pb);
 
             if(state == MKBETAG('I', 'N', 'D', 'X')){
-                len = get_be16(pb) - 6;
+                int n_pkts, expected_len;
+                len = get_be32(pb);
+                url_fskip(pb, 2);
+                n_pkts = get_be32(pb);
+                expected_len = 20 + n_pkts * 14;
+                if (len == 20)
+                    /* some files don't add index entries to chunk size... */
+                    len = expected_len;
+                else if (len != expected_len)
+                    av_log(s, AV_LOG_WARNING,
+                           "Index size %d (%d pkts) is wrong, should be %d.\n",
+                           len, n_pkts, expected_len);
+                len -= 14; // we already read part of the index header
                 if(len<0)
                     continue;
                 goto skip;