/*

 *  Copyright (c) 2018 The WebM project authors. All Rights Reserved.

 *

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

 */

/*

 * Fuzzer for libvpx decoders

 * ==========================

 * Requirements

 * --------------

 * Requires Clang 6.0 or above as -fsanitize=fuzzer is used as a linker

 * option.

 * Steps to build

 * --------------

 * Clone libvpx repository

   $git clone https://chromium.googlesource.com/webm/libvpx

 * Create a directory in parallel to libvpx and change directory

   $mkdir vpx_dec_fuzzer

   $cd vpx_dec_fuzzer/

 * Enable sanitizers (Supported: address integer memory thread undefined)

   $source ../libvpx/tools/set_analyzer_env.sh address

 * Configure libvpx.

 * Note --size-limit and VPX_MAX_ALLOCABLE_MEMORY are defined to avoid

 * Out of memory errors when running generated fuzzer binary

   $../libvpx/configure --disable-unit-tests --size-limit=12288x12288 \

   --extra-cflags="-fsanitize=fuzzer-no-link \

   -DVPX_MAX_ALLOCABLE_MEMORY=1073741824" \

   --disable-webm-io --enable-debug --disable-vp8-encoder \

   --disable-vp9-encoder --disable-examples

 * Build libvpx

   $make -j32

 * Build vp9 fuzzer

   $ $CXX $CXXFLAGS -std=gnu++17 -Wall -Wextra -Wimplicit-fallthrough \

   -DDECODER=vp9 -fsanitize=fuzzer -I../libvpx -I. -Wl,--start-group \

   ../libvpx/examples/vpx_dec_fuzzer.cc -o ./vpx_dec_fuzzer_vp9 \

   ./libvpx.a -Wl,--end-group

 * DECODER should be defined as vp9 or vp8 to enable vp9/vp8

 *

 * create a corpus directory and copy some ivf files there.

 * Based on which codec (vp8/vp9) is being tested, it is recommended to

 * have corresponding ivf files in corpus directory

 * Empty corpus directoy also is acceptable, though not recommended

   $mkdir CORPUS && cp some-files CORPUS

 * Run fuzzing:

   $./vpx_dec_fuzzer_vp9 CORPUS

 * References:

 * http://llvm.org/docs/LibFuzzer.html

 * https://github.com/google/oss-fuzz

 */

#include <stddef.h>

#include <stdint.h>

#include <stdio.h>

#include <stdlib.h>

#include <algorithm>

#include <memory>

#include "third_party/nalloc/nalloc.h"

#include "vpx/vp8dx.h"

#include "vpx/vpx_decoder.h"

#include "vpx_ports/mem_ops.h"

#define IVF_FRAME_HDR_SZ (4 + 8) /* 4 byte size + 8 byte timestamp */

#define IVF_FILE_HDR_SZ 32

#define VPXD_INTERFACE(name) VPXD_INTERFACE_(name)

#define VPXD_INTERFACE_(name) vpx_codec_##name##_dx()

extern "C" void usage_exit(void) { exit(EXIT_FAILURE); }

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

  if (size <= IVF_FILE_HDR_SZ) {

    return 0;

  }

  nalloc_init(nullptr);

  vpx_codec_ctx_t codec;

  // Set thread count in the range [1, 64].

  const unsigned int threads = (data[IVF_FILE_HDR_SZ] & 0x3f) + 1;

  vpx_codec_dec_cfg_t cfg = { threads, 0, 0 };

  vpx_codec_flags_t flags = 0;

  if ((data[IVF_FILE_HDR_SZ] & 0x40) != 0) {

    flags |= VPX_CODEC_USE_POSTPROC;

  }

  vpx_codec_err_t err =

      vpx_codec_dec_init(&codec, VPXD_INTERFACE(DECODER), &cfg, flags);

  if (err == VPX_CODEC_INCAPABLE) {

    // vpx_codec_dec_init may fail with VPX_CODEC_USE_POSTPROC

    // if the library is configured with --disable-postproc.

    flags = 0;

    if (vpx_codec_dec_init(&codec, VPXD_INTERFACE(DECODER), &cfg, flags)) {

      return 0;

    }

  } else if (err != 0) {

    return 0;

  }

  nalloc_start(data, size);

  if (threads > 1) {

    const int enable = (data[IVF_FILE_HDR_SZ] & 0xa0) != 0;

    err = vpx_codec_control(&codec, VP9D_SET_LOOP_FILTER_OPT, enable);

  }

  data += IVF_FILE_HDR_SZ;

  size -= IVF_FILE_HDR_SZ;

  int frame_cnt = 0;

  while (size > IVF_FRAME_HDR_SZ) {

    size_t frame_size = mem_get_le32(data);

    size -= IVF_FRAME_HDR_SZ;

    data += IVF_FRAME_HDR_SZ;

    frame_size = std::min(size, frame_size);

    vpx_codec_stream_info_t stream_info;

    stream_info.sz = sizeof(stream_info);

    err = vpx_codec_peek_stream_info(VPXD_INTERFACE(DECODER), data, size,

                                     &stream_info);

    ++frame_cnt;

    if (flags & VPX_CODEC_USE_POSTPROC) {

      if (frame_cnt % 16 == 4) {

        vp8_postproc_cfg_t pp = { 0, 0, 0 };

        if (vpx_codec_control(&codec, VP8_SET_POSTPROC, &pp)) goto fail;

      } else if (frame_cnt % 16 == 12) {

        vp8_postproc_cfg_t pp = { VP8_DEBLOCK | VP8_DEMACROBLOCK | VP8_MFQE, 4,

                                  0 };

        if (vpx_codec_control(&codec, VP8_SET_POSTPROC, &pp)) goto fail;

      }

    }

    err = vpx_codec_decode(&codec, data, frame_size, nullptr, 0);

    static_cast<void>(err);

    vpx_codec_iter_t iter = nullptr;

    vpx_image_t *img = nullptr;

    while ((img = vpx_codec_get_frame(&codec, &iter)) != nullptr) {

    }

    data += frame_size;

    size -= frame_size;

  }

fail:

  vpx_codec_destroy(&codec);

  nalloc_end();

  return 0;

}