avcodec/codec_internal: Add FFCodec, hide internal part of AVCodec

Up until now, codec.h contains both public and private parts
of AVCodec. This exposes the internals of AVCodec to users
and leads them into the temptation of actually using them
and forces us to forward-declare structures and types that
users can't use at all.

This commit changes this by adding a new structure FFCodec to
codec_internal.h that extends AVCodec, i.e. contains the public
AVCodec as first member; the private fields of AVCodec are moved
to this structure, leaving codec.h clean.

Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 14 insertions, 13 deletions

diff --git a/tools/target_dec_fuzzer.c b/tools/target_dec_fuzzer.c
index 2fea29a308..288aa63313 100644
--- a/tools/target_dec_fuzzer.c
+++ b/tools/target_dec_fuzzer.c
@@ -54,6 +54,7 @@
 
 #include "libavcodec/avcodec.h"
 #include "libavcodec/bytestream.h"
+#include "libavcodec/codec_internal.h"
 #include "libavformat/avformat.h"
 
 //For FF_SANE_NB_CHANNELS, so we dont waste energy testing things that will get instantly rejected
@@ -61,7 +62,7 @@
 
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
 
-extern const AVCodec * codec_list[];
+extern const FFCodec * codec_list[];
 
 static void error(const char *err)
 {
@@ -69,15 +70,15 @@ static void error(const char *err)
     exit(1);
 }
 
-static const AVCodec *c = NULL;
-static const AVCodec *AVCodecInitialize(enum AVCodecID codec_id)
+static const FFCodec *c = NULL;
+static const FFCodec *AVCodecInitialize(enum AVCodecID codec_id)
 {
     const AVCodec *res;
 
     res = avcodec_find_decoder(codec_id);
     if (!res)
         error("Failed to find decoder");
-    return res;
+    return ffcodec(res);
 }
 
 static int subtitle_handler(AVCodecContext *avctx, void *frame,
@@ -127,11 +128,11 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 #ifdef FFMPEG_DECODER
 #define DECODER_SYMBOL0(CODEC) ff_##CODEC##_decoder
 #define DECODER_SYMBOL(CODEC) DECODER_SYMBOL0(CODEC)
-        extern AVCodec DECODER_SYMBOL(FFMPEG_DECODER);
+        extern FFCodec DECODER_SYMBOL(FFMPEG_DECODER);
         codec_list[0] = &DECODER_SYMBOL(FFMPEG_DECODER);
 
 #if FFMPEG_DECODER == tiff || FFMPEG_DECODER == tdsc
-        extern AVCodec DECODER_SYMBOL(mjpeg);
+        extern FFCodec DECODER_SYMBOL(mjpeg);
         codec_list[1] = &DECODER_SYMBOL(mjpeg);
 #endif
 
@@ -142,17 +143,17 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         av_log_set_level(AV_LOG_PANIC);
     }
 
-    switch (c->type) {
+    switch (c->p.type) {
     case AVMEDIA_TYPE_AUDIO   :
     case AVMEDIA_TYPE_VIDEO   : decode_handler = audio_video_handler  ; break;
     case AVMEDIA_TYPE_SUBTITLE: decode_handler = subtitle_handler     ; break;
     }
-    switch (c->id) {
+    switch (c->p.id) {
     case AV_CODEC_ID_APE:       maxsamples_per_frame /= 256; break;
     }
     maxpixels = maxpixels_per_frame * maxiteration;
     maxsamples = maxsamples_per_frame * maxiteration;
-    switch (c->id) {
+    switch (c->p.id) {
     case AV_CODEC_ID_AGM:         maxpixels  /= 1024;  break;
     case AV_CODEC_ID_ARBC:        maxpixels  /= 1024;  break;
     case AV_CODEC_ID_BINKVIDEO:   maxpixels  /= 32;    break;
@@ -231,7 +232,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     maxsamples_per_frame = FFMIN(maxsamples_per_frame, maxsamples);
     maxpixels_per_frame  = FFMIN(maxpixels_per_frame , maxpixels);
 
-    AVCodecContext* ctx = avcodec_alloc_context3(c);
+    AVCodecContext* ctx = avcodec_alloc_context3(&c->p);
     AVCodecContext* parser_avctx = avcodec_alloc_context3(NULL);
     if (!ctx || !parser_avctx)
         error("Failed memory allocation");
@@ -257,7 +258,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         // Try to initialize a parser for this codec, note, this may fail which just means we test without one
         flags = bytestream2_get_byte(&gbc);
         if (flags & 1)
-            parser = av_parser_init(c->id);
+            parser = av_parser_init(c->p.id);
         if (flags & 2)
             ctx->strict_std_compliance = FF_COMPLIANCE_EXPERIMENTAL;
         if (flags & 4) {
@@ -265,7 +266,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
             if (flags & 8)
                 ctx->err_recognition |= AV_EF_EXPLODE;
         }
-        if ((flags & 0x10) && c->id != AV_CODEC_ID_H264)
+        if ((flags & 0x10) && c->p.id != AV_CODEC_ID_H264)
             ctx->flags2 |= AV_CODEC_FLAG2_FAST;
         if (flags & 0x80)
             ctx->flags2 |= AV_CODEC_FLAG2_EXPORT_MVS;
@@ -349,7 +350,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
             ctx->width = ctx->height = 0;
     }
 
-    int res = avcodec_open2(ctx, c, &opts);
+    int res = avcodec_open2(ctx, &c->p, &opts);
     if (res < 0) {
         avcodec_free_context(&ctx);
         av_free(parser_avctx);