mirror of
https://github.com/webmproject/libwebp.git
synced 2025-07-14 21:09:55 +02:00
Refactor decoder library
- Move common defines to dec/webpi.h - Regularize naming and parameters of various "CheckAndSkip" functions. Also they return VP8StatusCode for clarity. - Move WebP header/chunk parsing functions to webpi.h - Fix a bug in static function GetFeatures() Change-Id: Ibc3da4ba210d860551724dc40741959750d66b89
This commit is contained in:
Urvang Joshi
James Zern
282
src/dec/webp.c
282
src/dec/webp.c
@ -17,8 +17,6 @@
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extern "C" {
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#endif
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#define RIFF_HEADER_SIZE 12
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//------------------------------------------------------------------------------
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// RIFF layout is:
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// 0ffset tag
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@ -31,7 +29,7 @@ extern "C" {
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// 20.... the VP8 bytes
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// Or,
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// 12..15 "VP8X": 4-bytes tags, describing the extended-VP8 chunk.
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// 16..19 size of the VP8X chunk starting at offset 8.
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// 16..19 size of the VP8X chunk starting at offset 20.
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// 20..23 VP8X flags bit-map corresponding to the chunk-types present.
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// 24..27 Width of the Canvas Image.
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// 28..31 Height of the Canvas Image.
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@ -44,25 +42,208 @@ static inline uint32_t get_le32(const uint8_t* const data) {
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return data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
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}
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uint32_t WebPCheckAndSkipRIFFHeader(const uint8_t** data_ptr,
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uint32_t* data_size_ptr,
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uint32_t* riff_size) {
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if (*data_size_ptr >= RIFF_HEADER_SIZE && !memcmp(*data_ptr, "RIFF", 4)) {
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if (memcmp(*data_ptr + 8, "WEBP", 4)) {
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return 0; // Wrong image file signature.
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VP8StatusCode WebPParseRIFF(const uint8_t** data, uint32_t* data_size,
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uint32_t* riff_size) {
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assert(data);
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assert(data_size);
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assert(riff_size);
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if (*data_size >= RIFF_HEADER_SIZE &&
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!memcmp(*data, "RIFF", TAG_SIZE)) {
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if (memcmp(*data + 8, "WEBP", TAG_SIZE)) {
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return VP8_STATUS_BITSTREAM_ERROR; // Wrong image file signature.
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} else {
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*riff_size = get_le32(*data_ptr + 4);
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if (*riff_size < RIFF_HEADER_SIZE) {
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return 0; // We should have at least one chunk.
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*riff_size = get_le32(*data + TAG_SIZE);
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// Check that we have at least one chunk (i.e "WEBP" + "VP8?nnnn").
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if (*riff_size < TAG_SIZE + CHUNK_HEADER_SIZE) {
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return VP8_STATUS_BITSTREAM_ERROR;
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}
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// We have a RIFF container. Skip it.
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*data_ptr += RIFF_HEADER_SIZE;
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*data_size_ptr -= RIFF_HEADER_SIZE;
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*data += RIFF_HEADER_SIZE;
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*data_size -= RIFF_HEADER_SIZE;
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}
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} else {
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*riff_size = 0; // Did not get full RIFF Header.
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}
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return 1;
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return VP8_STATUS_OK;
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}
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VP8StatusCode WebPParseVP8X(const uint8_t** data, uint32_t* data_size,
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uint32_t* bytes_skipped,
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int* width, int* height, uint32_t* flags) {
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assert(data);
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assert(data_size);
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assert(bytes_skipped);
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*bytes_skipped = 0;
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if (*data_size < CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE) {
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return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
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}
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if (!memcmp(*data, "VP8X", TAG_SIZE)) {
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const uint32_t chunk_size = get_le32(*data + TAG_SIZE);
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if (chunk_size != VP8X_CHUNK_SIZE) {
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return VP8_STATUS_BITSTREAM_ERROR; // Wrong chunk size.
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}
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if (flags) {
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*flags = get_le32(*data + 8);
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}
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if (width) {
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*width = get_le32(*data + 12);
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}
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if (height) {
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*height = get_le32(*data + 16);
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}
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// We have consumed 20 bytes from VP8X. Skip them.
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*bytes_skipped = CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
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*data += *bytes_skipped;
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*data_size -= *bytes_skipped;
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}
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return VP8_STATUS_OK;
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}
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VP8StatusCode WebPParseOptionalChunks(const uint8_t** data, uint32_t* data_size,
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uint32_t riff_size,
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uint32_t* bytes_skipped) {
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const uint8_t* buf;
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uint32_t buf_size;
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assert(data);
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assert(data_size);
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assert(bytes_skipped);
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buf = *data;
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buf_size = *data_size;
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*bytes_skipped = 0;
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while (1) {
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uint32_t chunk_size;
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uint32_t cur_skip_size;
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const uint32_t bytes_skipped_header = TAG_SIZE + // "WEBP".
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CHUNK_HEADER_SIZE + // "VP8Xnnnn".
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VP8X_CHUNK_SIZE; // Data.
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*data = buf;
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*data_size = buf_size;
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if (buf_size < CHUNK_HEADER_SIZE) { // Insufficient data.
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return VP8_STATUS_NOT_ENOUGH_DATA;
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}
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chunk_size = get_le32(buf + TAG_SIZE);
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cur_skip_size = CHUNK_HEADER_SIZE + chunk_size;
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// Check that total bytes skipped along with current chunk size
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// does not exceed riff_size.
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if (riff_size > 0 &&
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(bytes_skipped_header + *bytes_skipped + cur_skip_size > riff_size)) {
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return VP8_STATUS_BITSTREAM_ERROR; // Not a valid chunk size.
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}
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if (buf_size < cur_skip_size) { // Insufficient data.
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return VP8_STATUS_NOT_ENOUGH_DATA;
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}
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if (!memcmp(buf, "VP8 ", TAG_SIZE)) { // A valid VP8 header.
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return VP8_STATUS_OK; // Found.
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}
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// We have a full & valid chunk; skip it.
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buf += cur_skip_size;
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buf_size -= cur_skip_size;
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*bytes_skipped += cur_skip_size;
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}
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}
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VP8StatusCode WebPParseVP8Header(const uint8_t** data, uint32_t* data_size,
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uint32_t riff_size, uint32_t* bytes_skipped,
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uint32_t* vp8_chunk_size) {
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assert(data);
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assert(data_size);
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assert(bytes_skipped);
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assert(vp8_chunk_size);
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*bytes_skipped = 0;
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*vp8_chunk_size = 0;
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if (*data_size < CHUNK_HEADER_SIZE) {
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return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
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}
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if (!memcmp(*data, "VP8 ", TAG_SIZE)) {
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*vp8_chunk_size = get_le32(*data + TAG_SIZE);
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if (riff_size >= TAG_SIZE + CHUNK_HEADER_SIZE && // "WEBP" + "VP8 nnnn".
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(*vp8_chunk_size > riff_size - (TAG_SIZE + CHUNK_HEADER_SIZE))) {
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return VP8_STATUS_BITSTREAM_ERROR; // Inconsistent size information.
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}
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// We have consumed CHUNK_HEADER_SIZE bytes from VP8 Header. Skip them.
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*bytes_skipped = CHUNK_HEADER_SIZE;
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*data += *bytes_skipped;
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*data_size -= *bytes_skipped;
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}
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return VP8_STATUS_OK;
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}
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VP8StatusCode WebPParseHeaders(const uint8_t** data, uint32_t* data_size,
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uint32_t* vp8_size, uint32_t* bytes_skipped) {
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const uint8_t* buf;
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uint32_t buf_size;
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uint32_t riff_size;
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uint32_t vp8_size_tmp;
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uint32_t optional_data_size;
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uint32_t vp8x_skip_size;
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uint32_t vp8_skip_size;
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VP8StatusCode status;
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assert(data);
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assert(data_size);
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assert(vp8_size);
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assert(bytes_skipped);
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buf = *data;
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buf_size = *data_size;
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*vp8_size = 0;
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*bytes_skipped = 0;
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if (buf == NULL || buf_size < RIFF_HEADER_SIZE) {
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return VP8_STATUS_NOT_ENOUGH_DATA;
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}
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// Skip over RIFF header.
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if (WebPParseRIFF(&buf, &buf_size, &riff_size) != VP8_STATUS_OK) {
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return VP8_STATUS_BITSTREAM_ERROR; // Wrong RIFF Header.
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}
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// Skip over VP8x header.
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status = WebPParseVP8X(&buf, &buf_size, &vp8x_skip_size, NULL, NULL, NULL);
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if (status != VP8_STATUS_OK) {
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return status; // Wrong VP8X Chunk / Insufficient data.
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}
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if (vp8x_skip_size > 0) {
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// Skip over optional chunks.
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status = WebPParseOptionalChunks(&buf, &buf_size, riff_size,
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&optional_data_size);
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if (status != VP8_STATUS_OK) {
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return status; // Found an invalid chunk size / Insufficient data.
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}
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}
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// Skip over VP8 chunk header.
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status = WebPParseVP8Header(&buf, &buf_size, riff_size, &vp8_skip_size,
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&vp8_size_tmp);
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if (status != VP8_STATUS_OK) {
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return status; // Invalid VP8 header / Insufficient data.
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}
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if (vp8_skip_size > 0) {
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*vp8_size = vp8_size_tmp;
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}
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*bytes_skipped = buf - *data;
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assert(*bytes_skipped == *data_size - buf_size);
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*data = buf;
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*data_size = buf_size;
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return VP8_STATUS_OK;
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}
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//------------------------------------------------------------------------------
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@ -276,56 +457,58 @@ static void DefaultFeatures(WebPBitstreamFeatures* const features) {
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features->bitstream_version = 0;
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}
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static VP8StatusCode GetFeatures(const uint8_t** data, uint32_t* data_size,
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static VP8StatusCode GetFeatures(const uint8_t* data, uint32_t data_size,
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WebPBitstreamFeatures* const features) {
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uint32_t chunk_size = 0;
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uint32_t vp8_chunk_size = 0;
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uint32_t riff_size = 0;
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uint32_t flags = 0;
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int is_vp8x_chunk = 0;
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int is_vp8_chunk = 0;
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uint32_t vp8x_skip_size = 0;
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uint32_t vp8_skip_size = 0;
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VP8StatusCode status;
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if (features == NULL) {
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return VP8_STATUS_INVALID_PARAM;
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}
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DefaultFeatures(features);
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if (data == NULL || *data == NULL || data_size == 0) {
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if (data == NULL) {
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return VP8_STATUS_INVALID_PARAM;
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}
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if (!WebPCheckAndSkipRIFFHeader(data, data_size, &riff_size)) {
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return VP8_STATUS_BITSTREAM_ERROR; // Wrong RIFF Header.
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// Skip over RIFF header.
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status = WebPParseRIFF(&data, &data_size, &riff_size);
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if (status != VP8_STATUS_OK) {
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return status; // Wrong RIFF Header / Insufficient data.
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}
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if (!VP8XGetInfo(data, data_size, &is_vp8x_chunk,
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&features->width, &features->height, &flags)) {
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return VP8_STATUS_BITSTREAM_ERROR; // Wrong VP8X Chunk-header.
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// Skip over VP8x.
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status = WebPParseVP8X(&data, &data_size, &vp8x_skip_size, &features->width,
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&features->height, &flags);
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if (status != VP8_STATUS_OK) {
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return status; // Wrong VP8X / insufficient data.
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}
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if (vp8x_skip_size > 0) {
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return VP8_STATUS_OK; // Return features from VP8x header.
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}
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if (is_vp8x_chunk > 0) {
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return VP8_STATUS_OK;
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// Skip over VP8 header.
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status = WebPParseVP8Header(&data, &data_size, riff_size, &vp8_skip_size,
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&vp8_chunk_size);
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if (status != VP8_STATUS_OK) {
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return status; // Wrong VP8 Chunk-header / insufficient data.
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}
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if (!VP8CheckAndSkipHeader(data, data_size, &is_vp8_chunk, &chunk_size,
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riff_size)) {
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return VP8_STATUS_BITSTREAM_ERROR; // Invalid VP8 header.
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}
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if (is_vp8_chunk == -1) {
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return VP8_STATUS_BITSTREAM_ERROR; // Insufficient data-bytes.
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}
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if (!is_vp8_chunk) {
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chunk_size = *data_size; // No VP8 chunk wrapper over raw VP8 data.
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if (vp8_skip_size == 0) {
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vp8_chunk_size = data_size; // No VP8 chunk wrapper over raw VP8 data.
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}
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// Validates raw VP8 data.
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if (!VP8GetInfo(*data, *data_size, chunk_size,
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if (!VP8GetInfo(data, data_size, vp8_chunk_size,
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&features->width, &features->height, &features->has_alpha)) {
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return VP8_STATUS_BITSTREAM_ERROR;
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}
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return VP8_STATUS_OK;
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return VP8_STATUS_OK; // Return features from VP8 header.
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}
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//------------------------------------------------------------------------------
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@ -335,7 +518,7 @@ int WebPGetInfo(const uint8_t* data, uint32_t data_size,
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int* width, int* height) {
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WebPBitstreamFeatures features;
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if (GetFeatures(&data, &data_size, &features) != VP8_STATUS_OK) {
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if (GetFeatures(data, data_size, &features) != VP8_STATUS_OK) {
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return 0;
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}
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@ -368,14 +551,20 @@ int WebPInitDecoderConfigInternal(WebPDecoderConfig* const config,
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VP8StatusCode WebPGetFeaturesInternal(const uint8_t* data, uint32_t data_size,
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WebPBitstreamFeatures* const features,
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int version) {
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int version) {
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VP8StatusCode status;
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if (version != WEBP_DECODER_ABI_VERSION) {
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return VP8_STATUS_INVALID_PARAM; // version mismatch
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}
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if (features == NULL) {
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return VP8_STATUS_INVALID_PARAM;
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}
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return GetFeatures(&data, &data_size, features);
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status = GetFeatures(data, data_size, features);
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if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
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return VP8_STATUS_BITSTREAM_ERROR; // Not enough data treated as error.
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}
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return status;
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}
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VP8StatusCode WebPDecode(const uint8_t* data, uint32_t data_size,
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@ -387,8 +576,11 @@ VP8StatusCode WebPDecode(const uint8_t* data, uint32_t data_size,
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return VP8_STATUS_INVALID_PARAM;
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}
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status = GetFeatures(&data, &data_size, &config->input);
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status = GetFeatures(data, data_size, &config->input);
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if (status != VP8_STATUS_OK) {
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if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
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return VP8_STATUS_BITSTREAM_ERROR; // Not enough data treated as error.
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}
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return status;
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}
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