[PATCH] Mp4: fixed setting wrong mdat atom size in very rarecases.

[胡聪 (hucc)]

Hi,

On Mon, Nov 21, 2016 at 10:26 PM +0300, Maxim Dounin wrote:

>Ah, ok, I see the problem now.  Please clarify things in the 
>commit log as well.
>
>It also make sense to use sizeof() explicitly, instead of 
>introducing a magic number, e.g.:

Thanks！There is the new patch.

# HG changeset patch
# User hucongcong <hucong.c at foxmail.com>
# Date 1479740605 -28800
#      Mon Nov 21 23:03:25 2016 +0800
# Node ID 7a1a6f7b989d4c44523333293265d58663ac7ff4
# Parent  2c7a2d75938a31044552b0a6cd6edaebdaf0bd69
Mp4: fixed setting wrong mdat atom size in very rare cases.

Atom size is the sum of atom header size and atom data size. The
specification says that the first 4 bytes are set to one when
the atom size is greater than the maximum unsigned 32-bit value.
Which means atom header size should be considered when the
comparison takes place between atom data size and 0xffffffff.

diff -r 2c7a2d75938a -r 7a1a6f7b989d src/http/modules/ngx_http_mp4_module.c
--- a/src/http/modules/ngx_http_mp4_module.c	Mon Nov 21 16:49:19 2016 +0300
+++ b/src/http/modules/ngx_http_mp4_module.c	Mon Nov 21 23:03:25 2016 +0800
@@ -1229,7 +1229,9 @@ ngx_http_mp4_update_mdat_atom(ngx_http_m
 
     atom_header = mp4->mdat_atom_header;
 
-    if ((uint64_t) atom_data_size > (uint64_t) 0xffffffff) {
+    if ((uint64_t) atom_data_size + sizeof(ngx_mp4_atom_header_t)
+            > (uint64_t) 0xffffffff)
+    {
         atom_size = 1;
         atom_header_size = sizeof(ngx_mp4_atom_header64_t);
         ngx_mp4_set_64value(atom_header + sizeof(ngx_mp4_atom_header_t),