Add compatibility wrappers for functions moved from lavf to lavc

When symbol versioning is enabled, moving symbols from one library to
another breaks binary compatibility.  This adds wrappers with the old
version tag for the av_*packet functions recently moved to lavc.

Originally committed as revision 23611 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1084,6 +1084,9 @@ HAVE_LIST="
     struct_sockaddr_in6
     struct_sockaddr_sa_len
     struct_sockaddr_storage
+    symver
+    symver_gnu_asm
+    symver_asm_label
     sys_mman_h
     sys_resource_h
     sys_select_h
@@ -1198,6 +1201,8 @@ fast_unaligned_if_any="armv6 ppc x86"
 need_memalign="altivec neon sse"
 inline_asm_deps="!tms470"
 
+symver_if_any="symver_asm_label symver_gnu_asm"
+
 # subsystems
 mdct_select="fft"
 rdft_select="fft"
@@ -2714,8 +2719,17 @@ check_ldflags '-Wl,-rpath-link,\$(BUILD_ROOT)/libpostproc -Wl,-rpath-link,\$(BUI
 check_ldflags -Wl,-Bsymbolic
 
 echo "X{};" > $TMPV
-test_ldflags -Wl,--version-script,$TMPV &&
+if test_ldflags -Wl,--version-script,$TMPV; then
     append SHFLAGS '-Wl,--version-script,\$(SUBDIR)lib\$(NAME).ver'
+    check_cc <<EOF && enable symver_asm_label
+void ff_foo(void) __asm__ ("av_foo@VERSION");
+void ff_foo(void) {}
+EOF
+    check_cc <<EOF && enable symver_gnu_asm
+__asm__(".symver ff_foo,av_foo@VERSION");
+void ff_foo(void) {}
+EOF
+fi
 
 if enabled small; then
     add_cflags $size_cflags

libavformat/utils.c

@@ -283,8 +283,38 @@ AVInputFormat *av_find_input_format(const char *short_name)
     return NULL;
 }
 
-/* memory handling */
+#if LIBAVFORMAT_VERSION_MAJOR < 53 && CONFIG_SHARED && HAVE_SYMVER
+FF_SYMVER(void, av_destruct_packet_nofree, (AVPacket *pkt), "LIBAVFORMAT_52")
+{
+    av_destruct_packet_nofree(pkt);
+}
+
+FF_SYMVER(void, av_destruct_packet, (AVPacket *pkt), "LIBAVFORMAT_52")
+{
+    av_destruct_packet(pkt);
+}
+
+FF_SYMVER(int, av_new_packet, (AVPacket *pkt, int size), "LIBAVFORMAT_52")
+{
+    return av_new_packet(pkt, size);
+}
+
+FF_SYMVER(int, av_dup_packet, (AVPacket *pkt), "LIBAVFORMAT_52")
+{
+    return av_dup_packet(pkt);
+}
+
+FF_SYMVER(void, av_free_packet, (AVPacket *pkt), "LIBAVFORMAT_52")
+{
+    av_free_packet(pkt);
+}
 
+FF_SYMVER(void, av_init_packet, (AVPacket *pkt), "LIBAVFORMAT_52")
+{
+    av_log(NULL, AV_LOG_WARNING, "Diverting av_*_packet function calls to libavcodec. Recompile to improve performance\n");
+    av_init_packet(pkt);
+}
+#endif
 
 int av_get_packet(ByteIOContext *s, AVPacket *pkt, int size)
 {

libavutil/internal.h

@@ -196,4 +196,15 @@
 #   define NULL_IF_CONFIG_SMALL(x) x
 #endif
 
+#if HAVE_SYMVER_ASM_LABEL
+#   define FF_SYMVER(type, name, args, ver)             \
+    type ff_##name args __asm__ (#name "@" ver);        \
+    type ff_##name args
+#elif HAVE_SYMVER_GNU_ASM
+#   define FF_SYMVER(type, name, args, ver)             \
+    __asm__ (".symver ff_" #name "," #name "@" ver);    \
+    type ff_##name args;                                \
+    type ff_##name args
+#endif
+
 #endif /* AVUTIL_INTERNAL_H */