ffmpeg/ffmpeg-dlopen-openh264.patch

From 23c6bb2850b82c473e67df111333479805b0ba4b Mon Sep 17 00:00:00 2001
From: Neal Gompa <ngompa@fedoraproject.org>
Date: Tue, 15 Feb 2022 10:29:05 -0500
Subject: [PATCH] avcodec/openh264: Add the ability to dlopen() OpenH264

We can't directly depend on OpenH264, but we can weakly link to it
and gracefully expose the capability.

Co-authored-by: Andreas Schneider <asn@cryptomilk.org>
Co-authored-by: Neal Gompa <ngompa@fedoraproject.org>

Signed-off-by: Neal Gompa <ngompa@fedoraproject.org>
---
 configure                       |   3 +
 libavcodec/libopenh264.c        |  11 +++
 libavcodec/libopenh264_dlopen.h | 164 ++++++++++++++++++++++++++++++++
 libavcodec/libopenh264dec.c     |   9 ++
 libavcodec/libopenh264enc.c     |   9 ++
 5 files changed, 196 insertions(+)
 create mode 100644 libavcodec/libopenh264_dlopen.h

diff --git a/configure b/configure
index 6b5ef6332e..f08e566e98 100755
--- a/configure
+++ b/configure
@@ -250,6 +250,7 @@ External library support:
   --enable-libopencore-amrwb enable AMR-WB decoding via libopencore-amrwb [no]
   --enable-libopencv       enable video filtering via libopencv [no]
   --enable-libopenh264     enable H.264 encoding via OpenH264 [no]
+  --enable-libopenh264-dlopen  enable H.264 encoding via dlopen()'ed OpenH264 [no]
   --enable-libopenjpeg     enable JPEG 2000 de/encoding via OpenJPEG [no]
   --enable-libopenmpt      enable decoding tracked files via libopenmpt [no]
   --enable-libopenvino     enable OpenVINO as a DNN module backend
@@ -1839,6 +1840,7 @@ EXTERNAL_LIBRARY_LIST="
     libmysofa
     libopencv
     libopenh264
+    libopenh264_dlopen
     libopenjpeg
     libopenmpt
     libopenvino
@@ -6575,6 +6577,7 @@ enabled libopencv         && { check_headers opencv2/core/core_c.h &&
                                  require libopencv opencv2/core/core_c.h cvCreateImageHeader -lopencv_core -lopencv_imgproc; } ||
                                require_pkg_config libopencv opencv opencv/cxcore.h cvCreateImageHeader; }
 enabled libopenh264       && require_pkg_config libopenh264 openh264 wels/codec_api.h WelsGetCodecVersion
+enabled libopenh264_dlopen && enable libopenh264 && add_cppflags "-I$(dirname `readlink -f $0`)/ffdlopenhdrs/include -DCONFIG_LIBOPENH264_DLOPEN=1"
 enabled libopenjpeg       && { check_pkg_config libopenjpeg "libopenjp2 >= 2.1.0" openjpeg.h opj_version ||
                                { require_pkg_config libopenjpeg "libopenjp2 >= 2.1.0" openjpeg.h opj_version -DOPJ_STATIC && add_cppflags -DOPJ_STATIC; } }
 enabled libopenmpt        && require_pkg_config libopenmpt "libopenmpt >= 0.2.6557" libopenmpt/libopenmpt.h openmpt_module_create -lstdc++ && append libopenmpt_extralibs "-lstdc++"
diff --git a/libavcodec/libopenh264.c b/libavcodec/libopenh264.c
index 59c61a3a4c..382a34562a 100644
--- a/libavcodec/libopenh264.c
+++ b/libavcodec/libopenh264.c
@@ -20,8 +20,13 @@
  */
 
 #include <string.h>
+
+#ifdef CONFIG_LIBOPENH264_DLOPEN
+#include "libopenh264_dlopen.h"
+#else
 #include <wels/codec_api.h>
 #include <wels/codec_ver.h>
+#endif
 
 #include "libavutil/log.h"
 
@@ -52,6 +57,12 @@ int ff_libopenh264_check_version(void *logctx)
     // function (for functions returning larger structs), thus skip the check in those
     // configurations.
 #if !defined(_WIN32) || !defined(__GNUC__) || !ARCH_X86_32 || AV_GCC_VERSION_AT_LEAST(4, 7)
+
+#ifdef CONFIG_LIBOPENH264_DLOPEN
+    if (loadLibOpenH264(logctx))
+         return -1;
+#endif
+
     OpenH264Version libver = WelsGetCodecVersion();
     if (memcmp(&libver, &g_stCodecVersion, sizeof(libver))) {
         av_log(logctx, AV_LOG_ERROR, "Incorrect library version loaded\n");
diff --git a/libavcodec/libopenh264_dlopen.h b/libavcodec/libopenh264_dlopen.h
new file mode 100644
index 0000000000..c58fcd704d
--- /dev/null
+++ b/libavcodec/libopenh264_dlopen.h
@@ -0,0 +1,164 @@
+/*!
+ *@page License
+ *
+ * \copy
+ *     Copyright (c)  2022, Andreas Schneider <asn@cryptomilk.org>
+ *     All rights reserved.
+ *
+ *     Redistribution and use in source and binary forms, with or without
+ *     modification, are permitted provided that the following conditions
+ *     are met:
+ *
+ *        * Redistributions of source code must retain the above copyright
+ *          notice, this list of conditions and the following disclaimer.
+ *
+ *        * Redistributions in binary form must reproduce the above copyright
+ *          notice, this list of conditions and the following disclaimer in
+ *          the documentation and/or other materials provided with the
+ *          distribution.
+ *
+ *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *     "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *     LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ *     FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ *     COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ *     INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ *     BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ *     CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ *     LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ *     ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *     POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifdef CONFIG_LIBOPENH264_DLOPEN
+
+#include <dlfcn.h>
+
+#include <wels/codec_api.h>
+#include <wels/codec_ver.h>
+
+#include "avcodec.h"
+/*
+ * The symbol binding makes sure we do not run into strict aliasing issues which
+ * can lead into segfaults.
+ */
+typedef int (*__oh264_WelsCreateSVCEncoder)(ISVCEncoder **);
+typedef void (*__oh264_WelsDestroySVCEncoder)(ISVCEncoder *);
+typedef int (*__oh264_WelsGetDecoderCapability)(SDecoderCapability *);
+typedef long (*__oh264_WelsCreateDecoder)(ISVCDecoder **);
+typedef void (*__oh264_WelsDestroyDecoder)(ISVCDecoder *);
+typedef OpenH264Version (*__oh264_WelsGetCodecVersion)(void);
+typedef void (*__oh264_WelsGetCodecVersionEx)(OpenH264Version *);
+
+#define OH264_SYMBOL_ENTRY(i)                                                  \
+  union {                                                                      \
+    __oh264_##i f;                                                             \
+    void *obj;                                                                 \
+  } _oh264_##i
+
+struct oh264_symbols {
+  OH264_SYMBOL_ENTRY(WelsCreateSVCEncoder);
+  OH264_SYMBOL_ENTRY(WelsDestroySVCEncoder);
+  OH264_SYMBOL_ENTRY(WelsGetDecoderCapability);
+  OH264_SYMBOL_ENTRY(WelsCreateDecoder);
+  OH264_SYMBOL_ENTRY(WelsDestroyDecoder);
+  OH264_SYMBOL_ENTRY(WelsGetCodecVersion);
+  OH264_SYMBOL_ENTRY(WelsGetCodecVersionEx);
+};
+
+/* Symbols are bound by loadLibOpenH264() */
+static struct oh264_symbols openh264_symbols;
+
+static int oh264_WelsCreateSVCEncoder(ISVCEncoder **ppEncoder) {
+  return openh264_symbols._oh264_WelsCreateSVCEncoder.f(ppEncoder);
+}
+#define WelsCreateSVCEncoder oh264_WelsCreateSVCEncoder
+
+static void oh264_WelsDestroySVCEncoder(ISVCEncoder *pEncoder) {
+  return openh264_symbols._oh264_WelsDestroySVCEncoder.f(pEncoder);
+}
+#define WelsDestroySVCEncoder oh264_WelsDestroySVCEncoder
+
+static int oh264_WelsGetDecoderCapability(SDecoderCapability *pDecCapability) {
+  return openh264_symbols._oh264_WelsGetDecoderCapability.f(pDecCapability);
+}
+#define WelsGetDecoderCapability oh264_WelsGetDecoderCapability
+
+static long oh264_WelsCreateDecoder(ISVCDecoder **ppDecoder) {
+  return openh264_symbols._oh264_WelsCreateDecoder.f(ppDecoder);
+}
+#define WelsCreateDecoder oh264_WelsCreateDecoder
+
+static void oh264_WelsDestroyDecoder(ISVCDecoder *pDecoder) {
+  return openh264_symbols._oh264_WelsDestroyDecoder.f(pDecoder);
+}
+#define WelsDestroyDecoder oh264_WelsDestroyDecoder
+
+static OpenH264Version oh264_WelsGetCodecVersion(void) {
+  return openh264_symbols._oh264_WelsGetCodecVersion.f();
+}
+#define WelsGetCodecVersion oh264_WelsGetCodecVersion
+
+static void oh264_WelsGetCodecVersionEx(OpenH264Version *pVersion) {
+  openh264_symbols._oh264_WelsGetCodecVersionEx.f(pVersion);
+}
+#define WelsGetCodecVersionEx oh264_WelsGetCodecVersionEx
+
+static void *_oh264_bind_symbol(AVCodecContext *avctx,
+                                void *handle,
+                                const char *sym_name) {
+    void *sym = NULL;
+
+    sym = dlsym(handle, sym_name);
+    if (sym == NULL) {
+        const char *err = dlerror();
+        av_log(avctx,
+               AV_LOG_WARNING,
+               "%s: Failed to bind %s\n",
+               err,
+               sym_name);
+        return NULL;
+    }
+
+    return sym;
+}
+
+#define oh264_bind_symbol(avctx, handle, sym_name)                           \
+  if (openh264_symbols._oh264_##sym_name.obj == NULL) {                      \
+    openh264_symbols._oh264_##sym_name.obj = _oh264_bind_symbol(avctx, handle, #sym_name); \
+    if (openh264_symbols._oh264_##sym_name.obj == NULL) {                    \
+      return 1;                                                              \
+    }                                                                        \
+  }
+
+static int loadLibOpenH264(AVCodecContext *avctx) {
+  void *libopenh264 = NULL;
+  const char *err = NULL;
+
+#define OPENH264_LIB "libopenh264.so.6"
+  libopenh264 = dlopen(OPENH264_LIB, RTLD_LAZY);
+  err = dlerror();
+  if (err != NULL) {
+    av_log(avctx, AV_LOG_WARNING,
+           "%s: %s is missing, openh264 support will be disabled\n", err,
+           OPENH264_LIB);
+    if (libopenh264) {
+      dlclose(libopenh264);
+    }
+    return 1;
+  }
+
+  oh264_bind_symbol(avctx, libopenh264, WelsCreateSVCEncoder);
+  oh264_bind_symbol(avctx, libopenh264, WelsDestroySVCEncoder);
+  oh264_bind_symbol(avctx, libopenh264, WelsGetDecoderCapability);
+  oh264_bind_symbol(avctx, libopenh264, WelsCreateDecoder);
+  oh264_bind_symbol(avctx, libopenh264, WelsDestroyDecoder);
+  oh264_bind_symbol(avctx, libopenh264, WelsGetCodecVersion);
+  oh264_bind_symbol(avctx, libopenh264, WelsGetCodecVersionEx);
+
+  return 0;
+}
+
+#endif // CONFIG_LIBOPENH264_DLOPEN
diff --git a/libavcodec/libopenh264dec.c b/libavcodec/libopenh264dec.c
index 7f5e85402a..281e43c3c0 100644
--- a/libavcodec/libopenh264dec.c
+++ b/libavcodec/libopenh264dec.c
@@ -19,8 +19,12 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#ifdef CONFIG_LIBOPENH264_DLOPEN
+#include "libopenh264_dlopen.h"
+#else
 #include <wels/codec_api.h>
 #include <wels/codec_ver.h>
+#endif
 
 #include "libavutil/common.h"
 #include "libavutil/fifo.h"
@@ -55,6 +59,11 @@ static av_cold int svc_decode_init(AVCodecContext *avctx)
     int log_level;
     WelsTraceCallback callback_function;
 
+#ifdef CONFIG_LIBOPENH264_DLOPEN
+    if (loadLibOpenH264(avctx))
+         return -1;
+#endif
+
     if ((err = ff_libopenh264_check_version(avctx)) < 0)
         return err;
 
diff --git a/libavcodec/libopenh264enc.c b/libavcodec/libopenh264enc.c
index de4b85c411..555351982e 100644
--- a/libavcodec/libopenh264enc.c
+++ b/libavcodec/libopenh264enc.c
@@ -19,8 +19,12 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#ifdef CONFIG_LIBOPENH264_DLOPEN
+#include "libopenh264_dlopen.h"
+#else
 #include <wels/codec_api.h>
 #include <wels/codec_ver.h>
+#endif
 
 #include "libavutil/attributes.h"
 #include "libavutil/common.h"
@@ -136,6 +140,11 @@ static av_cold int svc_encode_init(AVCodecContext *avctx)
     WelsTraceCallback callback_function;
     AVCPBProperties *props;
 
+#ifdef CONFIG_LIBOPENH264_DLOPEN
+    if (loadLibOpenH264(avctx))
+         return -1;
+#endif
+
     if ((err = ff_libopenh264_check_version(avctx)) < 0)
         return err;
 
-- 
2.34.1