WebPMuxError MuxValidate()

in Extended/libwebp/src/mux/muxinternal.c [456:543]

• 62 lines of code
• 30 McCabe index (conditional complexity)

WebPMuxError MuxValidate(const WebPMux* const mux) {
  int num_iccp;
  int num_exif;
  int num_xmp;
  int num_anim;
  int num_frames;
  int num_vp8x;
  int num_images;
  int num_alpha;
  uint32_t flags;
  WebPMuxError err;

  // Verify mux is not NULL.
  if (mux == NULL) return WEBP_MUX_INVALID_ARGUMENT;

  // Verify mux has at least one image.
  if (mux->images_ == NULL) return WEBP_MUX_INVALID_ARGUMENT;

  err = WebPMuxGetFeatures(mux, &flags);
  if (err != WEBP_MUX_OK) return err;

  // At most one color profile chunk.
  err = ValidateChunk(mux, IDX_ICCP, ICCP_FLAG, flags, 1, &num_iccp);
  if (err != WEBP_MUX_OK) return err;

  // At most one EXIF metadata.
  err = ValidateChunk(mux, IDX_EXIF, EXIF_FLAG, flags, 1, &num_exif);
  if (err != WEBP_MUX_OK) return err;

  // At most one XMP metadata.
  err = ValidateChunk(mux, IDX_XMP, XMP_FLAG, flags, 1, &num_xmp);
  if (err != WEBP_MUX_OK) return err;

  // Animation: ANIMATION_FLAG, ANIM chunk and ANMF chunk(s) are consistent.
  // At most one ANIM chunk.
  err = ValidateChunk(mux, IDX_ANIM, NO_FLAG, flags, 1, &num_anim);
  if (err != WEBP_MUX_OK) return err;
  err = ValidateChunk(mux, IDX_ANMF, NO_FLAG, flags, -1, &num_frames);
  if (err != WEBP_MUX_OK) return err;

  {
    const int has_animation = !!(flags & ANIMATION_FLAG);
    if (has_animation && (num_anim == 0 || num_frames == 0)) {
      return WEBP_MUX_INVALID_ARGUMENT;
    }
    if (!has_animation && (num_anim == 1 || num_frames > 0)) {
      return WEBP_MUX_INVALID_ARGUMENT;
    }
    if (!has_animation) {
      const WebPMuxImage* images = mux->images_;
      // There can be only one image.
      if (images == NULL || images->next_ != NULL) {
        return WEBP_MUX_INVALID_ARGUMENT;
      }
      // Size must match.
      if (mux->canvas_width_ > 0) {
        if (images->width_ != mux->canvas_width_ ||
            images->height_ != mux->canvas_height_) {
          return WEBP_MUX_INVALID_ARGUMENT;
        }
      }
    }
  }

  // Verify either VP8X chunk is present OR there is only one elem in
  // mux->images_.
  err = ValidateChunk(mux, IDX_VP8X, NO_FLAG, flags, 1, &num_vp8x);
  if (err != WEBP_MUX_OK) return err;
  err = ValidateChunk(mux, IDX_VP8, NO_FLAG, flags, -1, &num_images);
  if (err != WEBP_MUX_OK) return err;
  if (num_vp8x == 0 && num_images != 1) return WEBP_MUX_INVALID_ARGUMENT;

  // ALPHA_FLAG & alpha chunk(s) are consistent.
  // Note: ALPHA_FLAG can be set when there is actually no Alpha data present.
  if (MuxHasAlpha(mux->images_)) {
    if (num_vp8x > 0) {
      // VP8X chunk is present, so it should contain ALPHA_FLAG.
      if (!(flags & ALPHA_FLAG)) return WEBP_MUX_INVALID_ARGUMENT;
    } else {
      // VP8X chunk is not present, so ALPH chunks should NOT be present either.
      err = WebPMuxNumChunks(mux, WEBP_CHUNK_ALPHA, &num_alpha);
      if (err != WEBP_MUX_OK) return err;
      if (num_alpha > 0) return WEBP_MUX_INVALID_ARGUMENT;
    }
  }

  return WEBP_MUX_OK;
}