[FFmpeg-devel] [PATCH 1/3 v2] doc/examples: Add fffuzz example

[Michael Niedermayer]

Hi

On Sat, Apr 16, 2016 at 12:12:41AM +0200, Pawel Golinski wrote:
> There are some afl specific macros inside,
> to make the example usable with afl fuzzer.
> ---
>  doc/examples/fffuzz.c | 370 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 370 insertions(+)
>  create mode 100644 doc/examples/fffuzz.c
> 
> diff --git a/doc/examples/fffuzz.c b/doc/examples/fffuzz.c
> new file mode 100644
> index 0000000..6672f42
> --- /dev/null
> +++ b/doc/examples/fffuzz.c
> @@ -0,0 +1,370 @@
> +/*
> + * Copyright (c) 2012 Stefano Sabatini
> + * Copyright (c) 2015 Andreas Cadhalpun

there was a review comment about this, please do not ignore review
comments
for reference;
>>> <kierank> the first patch in the patchset is my patch so I can't review it
>>> would suggest to me that he should be listed in the Copyright too

also when at this, please make sure the author metadata in the commits
is correct, i dont know who wrote what

also the code is still not hooked up to the build system


[...]
> +/**
> + * @file
> + * Demuxing and decoding (a codec/format combination) example.
> + *
> + * This can be useful for fuzz testing.
> + * @example ddcf.c
> + */
> +
> +#include <libavutil/avstring.h>
> +#include <libavutil/imgutils.h>
> +#include <libavutil/samplefmt.h>
> +#include <libavutil/timestamp.h>
> +#include <libavformat/avformat.h>
> +
> +/* needed for decoding video */
> +static int width, height;
> +static enum AVPixelFormat pix_fmt;
> +static uint8_t *video_dst_data[4] = {NULL};
> +static int      video_dst_linesize[4];
> +static int video_dst_bufsize;
> +
> +static int decode_packet(AVCodecContext *dec_ctx, FILE *dst_file, AVFrame *frame, int *got_frame, int *frame_count, AVPacket *pkt)
> +{
> +    int ret = -1;
> +    *got_frame = 0;
> +    AVSubtitle sub;
> +    unsigned i, j, k, l;
> +
> +    if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
> +        /* decode video frame */
> +        ret = avcodec_decode_video2(dec_ctx, frame, got_frame, pkt);
> +        if (ret < 0) {
> +            fprintf(stderr, "Error decoding video frame (%s)\n", av_err2str(ret));
> +            return ret;
> +        }
> +
> +        if (*got_frame) {
> +
> +            if (frame->width != width || frame->height != height ||
> +                frame->format != pix_fmt) {
> +                fprintf(stderr, "Error: input video width/height/format changed:\n"
> +                        "old: width = %d, height = %d, format = %s\n"
> +                        "new: width = %d, height = %d, format = %s\n",
> +                        width, height, av_get_pix_fmt_name(pix_fmt),
> +                        dec_ctx->width, dec_ctx->height,
> +                        av_get_pix_fmt_name(dec_ctx->pix_fmt));
> +                return -1;
> +            }
> +
> +            printf("video_frame n:%d coded_n:%d pts:%s\n",
> +                   *frame_count, frame->coded_picture_number,
> +                   av_ts2timestr(frame->pts, &dec_ctx->time_base));
> +
> +            /* copy decoded frame to destination buffer:
> +             * this is required since rawvideo expects non aligned data */
> +            av_image_copy(video_dst_data, video_dst_linesize,
> +                          (const uint8_t **)(frame->data), frame->linesize,
> +                          pix_fmt, width, height);
> +            *frame_count += 1;
> +
> +            /* write to rawvideo file */
> +            fwrite(video_dst_data[0], 1, video_dst_bufsize, dst_file);
> +        }
> +    } else if (dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
> +        /* decode audio frame */
> +        ret = avcodec_decode_audio4(dec_ctx, frame, got_frame, pkt);
> +        if (ret < 0) {
> +            fprintf(stderr, "Error decoding audio frame (%s)\n", av_err2str(ret));
> +            return ret;
> +        }

> +        /* Some audio decoders decode only part of the packet, and have to be
> +         * called again with the remainder of the packet data.
> +         * Sample: fate-suite/lossless-audio/luckynight-partial.shn
> +         * Also, some decoders might over-read the packet. */
> +        ret = FFMIN(ret, pkt->size);

overreads should not be ignored silently


[...]
> +static int open_codec_context(AVCodecContext **dec_ctx, AVFormatContext *fmt_ctx, char *codec)
> +{
> +    int ret = -1;
> +    AVCodec *dec = avcodec_find_decoder_by_name(codec);
> +    AVDictionary *opts = NULL;
> +    unsigned int i;
> +
> +    for (i = 0; i < fmt_ctx->nb_streams && i < INT_MAX; i += 1) {
> +        if (fmt_ctx->streams[i]->codec) {
> +            if (!dec || (fmt_ctx->streams[i]->codec->codec_id == dec->id)) {
> +                *dec_ctx = fmt_ctx->streams[i]->codec;
> +                ret = 0;
> +                break;
> +            }
> +        }
> +    }
> +
> +    if (ret < 0) {
> +        fprintf(stderr, "Could not find stream\n");
> +    } else {
> +        /* find decoder for the stream */
> +        if (!dec)
> +            dec = avcodec_find_decoder((*dec_ctx)->codec_id);
> +        if (!dec) {
> +            fprintf(stderr, "Failed to find decoder\n");
> +            return -1;
> +        }
> +

> +        /* Init the decoders, with or without reference counting */
> +        av_dict_set(&opts, "refcounted_frames", "1", 0);
> +        av_dict_set(&opts, "strict", "-2", 0);
> +        av_dict_set(&opts, "codec_whitelist", codec, 0);
> +        av_dict_set(&opts, "thread_type", "slice", 0);

missing failure checks


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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