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 --git a/src/http/modules/ngx_http_mp4_module.c b/src/http/modules/ngx_http_mp4_module.c
index 8f2920f64282a56fd6f5d52472fdd3337de640b2..f3c0fddb9d5d188ff169301a45c8df48dd1260eb 100644 (file)
--- a/src/http/modules/ngx_http_mp4_module.c
+++ b/src/http/modules/ngx_http_mp4_module.c
@@ -1229,7 +1229,9 @@ ngx_http_mp4_update_mdat_atom(ngx_http_mp4_file_t *mp4, off_t start_offset,
 
     atom_header = mp4->mdat_atom_header;
 
-    if ((uint64_t) atom_data_size > (uint64_t) 0xffffffff) {
+    if ((uint64_t) atom_data_size
+        > (uint64_t) 0xffffffff - sizeof(ngx_mp4_atom_header_t))
+    {
         atom_size = 1;
         atom_header_size = sizeof(ngx_mp4_atom_header64_t);
         ngx_mp4_set_64value(atom_header + sizeof(ngx_mp4_atom_header_t),