Add an av_register_protocol2 function that takes a size parameter

This allows extending the URLProtocol struct without breaking binary
compatibility with code compiled with older definitions of the struct.

Originally committed as revision 23702 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 22 insertions, 1 deletions

diff --git a/libavformat/avio.c b/libavformat/avio.c
index e79c8fcbfd..3371b40c4d 100644
--- a/libavformat/avio.c
+++ b/libavformat/avio.c
@@ -56,9 +56,14 @@ URLProtocol *av_protocol_next(URLProtocol *p)
     else  return first_protocol;
 }
 
-int av_register_protocol(URLProtocol *protocol)
+int av_register_protocol2(URLProtocol *protocol, int size)
 {
     URLProtocol **p;
+    if (size < sizeof(URLProtocol)) {
+        URLProtocol* temp = av_mallocz(sizeof(URLProtocol));
+        memcpy(temp, protocol, size);
+        protocol = temp;
+    }
     p = &first_protocol;
     while (*p != NULL) p = &(*p)->next;
     *p = protocol;
@@ -67,6 +72,22 @@ int av_register_protocol(URLProtocol *protocol)
 }
 
 #if LIBAVFORMAT_VERSION_MAJOR < 53
+/* The layout of URLProtocol as of when major was bumped to 52 */
+struct URLProtocol_compat {
+    const char *name;
+    int (*url_open)(URLContext *h, const char *filename, int flags);
+    int (*url_read)(URLContext *h, unsigned char *buf, int size);
+    int (*url_write)(URLContext *h, unsigned char *buf, int size);
+    int64_t (*url_seek)(URLContext *h, int64_t pos, int whence);
+    int (*url_close)(URLContext *h);
+    struct URLProtocol *next;
+};
+
+int av_register_protocol(URLProtocol *protocol)
+{
+    return av_register_protocol2(protocol, sizeof(struct URLProtocol_compat));
+}
+
 int register_protocol(URLProtocol *protocol)
 {
     return av_register_protocol(protocol);