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src/Source/LibWebP/src/mux/mux.muxinternal.c  view on Meta::CPAN

// Helper methods for mux.

int MuxHasAlpha(const WebPMuxImage* images) {
  while (images != NULL) {
    if (images->has_alpha_) return 1;
    images = images->next_;
  }
  return 0;
}

uint8_t* MuxEmitRiffHeader(uint8_t* const data, size_t size) {
  PutLE32(data + 0, MKFOURCC('R', 'I', 'F', 'F'));
  PutLE32(data + TAG_SIZE, (uint32_t)size - CHUNK_HEADER_SIZE);
  assert(size == (uint32_t)size);
  PutLE32(data + TAG_SIZE + CHUNK_SIZE_BYTES, MKFOURCC('W', 'E', 'B', 'P'));
  return data + RIFF_HEADER_SIZE;
}

WebPChunk** MuxGetChunkListFromId(const WebPMux* mux, WebPChunkId id) {
  assert(mux != NULL);
  switch (id) {
    case WEBP_CHUNK_VP8X:    return (WebPChunk**)&mux->vp8x_;
    case WEBP_CHUNK_ICCP:    return (WebPChunk**)&mux->iccp_;
    case WEBP_CHUNK_ANIM:    return (WebPChunk**)&mux->anim_;
    case WEBP_CHUNK_EXIF:    return (WebPChunk**)&mux->exif_;
    case WEBP_CHUNK_XMP:     return (WebPChunk**)&mux->xmp_;
    default:                 return (WebPChunk**)&mux->unknown_;
  }
}

static int IsNotCompatible(int feature, int num_items) {
  return (feature != 0) != (num_items > 0);
}

#define NO_FLAG 0

// Test basic constraints:
// retrieval, maximum number of chunks by index (use -1 to skip)
// and feature incompatibility (use NO_FLAG to skip).
// On success returns WEBP_MUX_OK and stores the chunk count in *num.
static WebPMuxError ValidateChunk(const WebPMux* const mux, CHUNK_INDEX idx,
                                  WebPFeatureFlags feature,
                                  uint32_t vp8x_flags,
                                  int max, int* num) {
  const WebPMuxError err =
      WebPMuxNumChunks(mux, kChunks[idx].id, num);
  if (err != WEBP_MUX_OK) return err;
  if (max > -1 && *num > max) return WEBP_MUX_INVALID_ARGUMENT;
  if (feature != NO_FLAG && IsNotCompatible(vp8x_flags & feature, *num)) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }
  return WEBP_MUX_OK;
}

WebPMuxError MuxValidate(const WebPMux* const mux) {
  int num_iccp;
  int num_exif;
  int num_xmp;
  int num_anim;
  int num_frames;
  int num_fragments;
  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;
    }
  }

  // Fragmentation: FRAGMENTS_FLAG and FRGM chunk(s) are consistent.
  err = ValidateChunk(mux, IDX_FRGM, FRAGMENTS_FLAG, flags, -1, &num_fragments);
  if (err != WEBP_MUX_OK) return err;

  // 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.
  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;
    }
  } else {  // Mux doesn't need alpha. So, ALPHA_FLAG should NOT be present.
    if (flags & ALPHA_FLAG) return WEBP_MUX_INVALID_ARGUMENT;
  }

  // num_fragments & num_images are consistent.
  if (num_fragments > 0 && num_images != num_fragments) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }

  return WEBP_MUX_OK;
}

#undef NO_FLAG

//------------------------------------------------------------------------------