view release on metacpan or  search on metacpan

src/Source/LibWebP/src/demux/demux.demux.c  view on Meta::CPAN

  if (dmux->loop_count_ < 0) return 0;
  if (dmux->state_ == WEBP_DEMUX_DONE && dmux->frames_ == NULL) return 0;
  if (is_fragmented) return 0;

  while (f != NULL) {
    const int cur_frame_set = f->frame_num_;
    int frame_count = 0, fragment_count = 0;

    // Check frame properties and if the image is composed of fragments that
    // each fragment came from a fragment.
    for (; f != NULL && f->frame_num_ == cur_frame_set; f = f->next_) {
      const ChunkData* const image = f->img_components_;
      const ChunkData* const alpha = f->img_components_ + 1;

      if (is_fragmented && !f->is_fragment_) return 0;
      if (!is_fragmented && f->is_fragment_) return 0;
      if (!is_animation && f->frame_num_ > 1) return 0;

      if (f->complete_) {
        if (alpha->size_ == 0 && image->size_ == 0) return 0;
        // Ensure alpha precedes image bitstream.
        if (alpha->size_ > 0 && alpha->offset_ > image->offset_) {
          return 0;
        }

        if (f->width_ <= 0 || f->height_ <= 0) return 0;
      } else {
        // There shouldn't be a partial frame in a complete file.
        if (dmux->state_ == WEBP_DEMUX_DONE) return 0;

        // Ensure alpha precedes image bitstream.
        if (alpha->size_ > 0 && image->size_ > 0 &&
            alpha->offset_ > image->offset_) {
          return 0;
        }
        // There shouldn't be any frames after an incomplete one.
        if (f->next_ != NULL) return 0;
      }

      if (f->width_ > 0 && f->height_ > 0 &&
          !CheckFrameBounds(f, !(is_animation || is_fragmented),
                            dmux->canvas_width_, dmux->canvas_height_)) {
        return 0;
      }

      fragment_count += f->is_fragment_;
      ++frame_count;
    }
    if (!is_fragmented && frame_count > 1) return 0;
    if (fragment_count > 0 && frame_count != fragment_count) return 0;
  }
  return 1;
}

// -----------------------------------------------------------------------------
// WebPDemuxer object

static void InitDemux(WebPDemuxer* const dmux, const MemBuffer* const mem) {
  dmux->state_ = WEBP_DEMUX_PARSING_HEADER;
  dmux->loop_count_ = 1;
  dmux->bgcolor_ = 0xFFFFFFFF;  // White background by default.
  dmux->canvas_width_ = -1;
  dmux->canvas_height_ = -1;
  dmux->frames_tail_ = &dmux->frames_;
  dmux->chunks_tail_ = &dmux->chunks_;
  dmux->mem_ = *mem;
}

WebPDemuxer* WebPDemuxInternal(const WebPData* data, int allow_partial,
                               WebPDemuxState* state, int version) {
  const ChunkParser* parser;
  int partial;
  ParseStatus status = PARSE_ERROR;
  MemBuffer mem;
  WebPDemuxer* dmux;

  if (state != NULL) *state = WEBP_DEMUX_PARSE_ERROR;

  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DEMUX_ABI_VERSION)) return NULL;
  if (data == NULL || data->bytes == NULL || data->size == 0) return NULL;

  if (!InitMemBuffer(&mem, data->bytes, data->size)) return NULL;
  status = ReadHeader(&mem);
  if (status != PARSE_OK) {
    if (state != NULL) {
      *state = (status == PARSE_NEED_MORE_DATA) ? WEBP_DEMUX_PARSING_HEADER
                                                : WEBP_DEMUX_PARSE_ERROR;
    }
    return NULL;
  }

  partial = (mem.buf_size_ < mem.riff_end_);
  if (!allow_partial && partial) return NULL;

  dmux = (WebPDemuxer*)WebPSafeCalloc(1ULL, sizeof(*dmux));
  if (dmux == NULL) return NULL;
  InitDemux(dmux, &mem);

  status = PARSE_ERROR;
  for (parser = kMasterChunks; parser->parse != NULL; ++parser) {
    if (!memcmp(parser->id, GetBuffer(&dmux->mem_), TAG_SIZE)) {
      status = parser->parse(dmux);
      if (status == PARSE_OK) dmux->state_ = WEBP_DEMUX_DONE;
      if (status == PARSE_NEED_MORE_DATA && !partial) status = PARSE_ERROR;
      if (status != PARSE_ERROR && !parser->valid(dmux)) status = PARSE_ERROR;
      if (status == PARSE_ERROR) dmux->state_ = WEBP_DEMUX_PARSE_ERROR;
      break;
    }
  }
  if (state != NULL) *state = dmux->state_;

  if (status == PARSE_ERROR) {
    WebPDemuxDelete(dmux);
    return NULL;
  }
  return dmux;
}

void WebPDemuxDelete(WebPDemuxer* dmux) {
  Chunk* c;
  Frame* f;