// Get the canvas width, height and flags after validating that VP8X/VP8/VP8L
// chunk and canvas size are valid.
static WebPMuxError MuxGetCanvasInfo(const WebPMux* const mux,
int* width, int* height, uint32_t* flags) {
int w, h;
uint32_t f = 0;
WebPData data;
assert(mux != NULL);
// Check if VP8X chunk is present.
if (MuxGet(mux, IDX_VP8X, 1, &data) == WEBP_MUX_OK) {
if (data.size < VP8X_CHUNK_SIZE) return WEBP_MUX_BAD_DATA;
f = GetLE32(data.bytes + 0);
w = GetLE24(data.bytes + 4) + 1;
h = GetLE24(data.bytes + 7) + 1;
} else {
const WebPMuxImage* const wpi = mux->images_;
// Grab user-forced canvas size as default.
w = mux->canvas_width_;
h = mux->canvas_height_;
if (w == 0 && h == 0 && ValidateForSingleImage(mux) == WEBP_MUX_OK) {
// single image and not forced canvas size => use dimension of first frame
assert(wpi != NULL);
w = wpi->width_;
h = wpi->height_;
}
if (wpi != NULL) {
if (wpi->has_alpha_) f |= ALPHA_FLAG;
}
}
if (w * (uint64_t)h >= MAX_IMAGE_AREA) return WEBP_MUX_BAD_DATA;
if (width != NULL) *width = w;
if (height != NULL) *height = h;
if (flags != NULL) *flags = f;
return WEBP_MUX_OK;
}
// Validates the RIFF container (if detected) and skips over it.
// If a RIFF container is detected, returns:
// VP8_STATUS_BITSTREAM_ERROR for invalid header,
// VP8_STATUS_NOT_ENOUGH_DATA for truncated data if have_all_data is true,
// and VP8_STATUS_OK otherwise.
// In case there are not enough bytes (partial RIFF container), return 0 for
// *riff_size. Else return the RIFF size extracted from the header.
static VP8StatusCode ParseRIFF(const uint8_t** const data,
size_t* const data_size, int have_all_data,
size_t* const riff_size) {
assert(data != NULL);
assert(data_size != NULL);
assert(riff_size != NULL);
*riff_size = 0; // Default: no RIFF present.
if (*data_size >= RIFF_HEADER_SIZE && !memcmp(*data, "RIFF", TAG_SIZE)) {
if (memcmp(*data + 8, "WEBP", TAG_SIZE)) {
return VP8_STATUS_BITSTREAM_ERROR; // Wrong image file signature.
} else {
const uint32_t size = GetLE32(*data + TAG_SIZE);
// Check that we have at least one chunk (i.e "WEBP" + "VP8?nnnn").
if (size < TAG_SIZE + CHUNK_HEADER_SIZE) {
return VP8_STATUS_BITSTREAM_ERROR;
}
if (size > MAX_CHUNK_PAYLOAD) {
return VP8_STATUS_BITSTREAM_ERROR;
}
if (have_all_data && (size > *data_size - CHUNK_HEADER_SIZE)) {
return VP8_STATUS_NOT_ENOUGH_DATA; // Truncated bitstream.
}
// We have a RIFF container. Skip it.
*riff_size = size;
*data += RIFF_HEADER_SIZE;
*data_size -= RIFF_HEADER_SIZE;
}
}
return VP8_STATUS_OK;
}
// Get the canvas width, height and flags after validating that VP8X/VP8/VP8L
// chunk and canvas size are valid.
static WebPMuxError MuxGetCanvasInfo(const WebPMux* const mux,
int* width, int* height, uint32_t* flags) {
int w, h;
uint32_t f = 0;
WebPData data;
assert(mux != NULL);
// Check if VP8X chunk is present.
if (MuxGet(mux, IDX_VP8X, 1, &data) == WEBP_MUX_OK) {
if (data.size < VP8X_CHUNK_SIZE) return WEBP_MUX_BAD_DATA;
f = GetLE32(data.bytes + 0);
w = GetLE24(data.bytes + 4) + 1;
h = GetLE24(data.bytes + 7) + 1;
} else { // Single image case.
const WebPMuxImage* const wpi = mux->images_;
WebPMuxError err = ValidateForSingleImage(mux);
if (err != WEBP_MUX_OK) return err;
assert(wpi != NULL);
w = wpi->width_;
h = wpi->height_;
if (wpi->has_alpha_) f |= ALPHA_FLAG;
}
if (w * (uint64_t)h >= MAX_IMAGE_AREA) return WEBP_MUX_BAD_DATA;
if (width != NULL) *width = w;
if (height != NULL) *height = h;
if (flags != NULL) *flags = f;
return WEBP_MUX_OK;
}
// Validates the VP8X header and skips over it.
// Returns VP8_STATUS_BITSTREAM_ERROR for invalid VP8X header,
// VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
// VP8_STATUS_OK otherwise.
// If a VP8X chunk is found, found_vp8x is set to true and *width_ptr,
// *height_ptr and *flags_ptr are set to the corresponding values extracted
// from the VP8X chunk.
static VP8StatusCode ParseVP8X(const uint8_t** const data,
size_t* const data_size,
int* const found_vp8x,
int* const width_ptr, int* const height_ptr,
uint32_t* const flags_ptr) {
const uint32_t vp8x_size = CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
assert(data != NULL);
assert(data_size != NULL);
assert(found_vp8x != NULL);
*found_vp8x = 0;
if (*data_size < CHUNK_HEADER_SIZE) {
return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
}
if (!memcmp(*data, "VP8X", TAG_SIZE)) {
int width, height;
uint32_t flags;
const uint32_t chunk_size = GetLE32(*data + TAG_SIZE);
if (chunk_size != VP8X_CHUNK_SIZE) {
return VP8_STATUS_BITSTREAM_ERROR; // Wrong chunk size.
}
// Verify if enough data is available to validate the VP8X chunk.
if (*data_size < vp8x_size) {
return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
}
flags = GetLE32(*data + 8);
width = 1 + GetLE24(*data + 12);
height = 1 + GetLE24(*data + 15);
if (width * (uint64_t)height >= MAX_IMAGE_AREA) {
return VP8_STATUS_BITSTREAM_ERROR; // image is too large
}
if (flags_ptr != NULL) *flags_ptr = flags;
if (width_ptr != NULL) *width_ptr = width;
if (height_ptr != NULL) *height_ptr = height;
// Skip over VP8X header bytes.
*data += vp8x_size;
*data_size -= vp8x_size;
*found_vp8x = 1;
}
return VP8_STATUS_OK;
}
// Fill the chunk with the given data (includes chunk header bytes), after some
// verifications.
static WebPMuxError ChunkVerifyAndAssign(WebPChunk* chunk,
const uint8_t* data, size_t data_size,
size_t riff_size, int copy_data) {
uint32_t chunk_size;
WebPData chunk_data;
// Sanity checks.
if (data_size < CHUNK_HEADER_SIZE) return WEBP_MUX_NOT_ENOUGH_DATA;
chunk_size = GetLE32(data + TAG_SIZE);
{
const size_t chunk_disk_size = SizeWithPadding(chunk_size);
if (chunk_disk_size > riff_size) return WEBP_MUX_BAD_DATA;
if (chunk_disk_size > data_size) return WEBP_MUX_NOT_ENOUGH_DATA;
}
// Data assignment.
chunk_data.bytes = data + CHUNK_HEADER_SIZE;
chunk_data.size = chunk_size;
return ChunkAssignData(chunk, &chunk_data, copy_data, GetLE32(data + 0));
}
WebPMuxError WebPMuxGetAnimationParams(const WebPMux* mux,
WebPMuxAnimParams* params) {
WebPData anim;
WebPMuxError err;
if (mux == NULL || params == NULL) return WEBP_MUX_INVALID_ARGUMENT;
err = MuxGet(mux, IDX_ANIM, 1, &anim);
if (err != WEBP_MUX_OK) return err;
if (anim.size < kChunks[WEBP_CHUNK_ANIM].size) return WEBP_MUX_BAD_DATA;
params->bgcolor = GetLE32(anim.bytes);
params->loop_count = GetLE16(anim.bytes + 4);
return WEBP_MUX_OK;
}
// Validates the VP8/VP8L Header ("VP8 nnnn" or "VP8L nnnn") and skips over it.
// Returns VP8_STATUS_BITSTREAM_ERROR for invalid (chunk larger than
// riff_size) VP8/VP8L header,
// VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
// VP8_STATUS_OK otherwise.
// If a VP8/VP8L chunk is found, *chunk_size is set to the total number of bytes
// extracted from the VP8/VP8L chunk header.
// The flag '*is_lossless' is set to 1 in case of VP8L chunk / raw VP8L data.
static VP8StatusCode ParseVP8Header(const uint8_t** const data_ptr,
size_t* const data_size, int have_all_data,
size_t riff_size, size_t* const chunk_size,
int* const is_lossless) {
const uint8_t* const data = *data_ptr;
const int is_vp8 = !memcmp(data, "VP8 ", TAG_SIZE);
const int is_vp8l = !memcmp(data, "VP8L", TAG_SIZE);
const uint32_t minimal_size =
TAG_SIZE + CHUNK_HEADER_SIZE; // "WEBP" + "VP8 nnnn" OR
// "WEBP" + "VP8Lnnnn"
assert(data != NULL);
assert(data_size != NULL);
assert(chunk_size != NULL);
assert(is_lossless != NULL);
if (*data_size < CHUNK_HEADER_SIZE) {
return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
}
if (is_vp8 || is_vp8l) {
// Bitstream contains VP8/VP8L header.
const uint32_t size = GetLE32(data + TAG_SIZE);
if ((riff_size >= minimal_size) && (size > riff_size - minimal_size)) {
return VP8_STATUS_BITSTREAM_ERROR; // Inconsistent size information.
}
if (have_all_data && (size > *data_size - CHUNK_HEADER_SIZE)) {
return VP8_STATUS_NOT_ENOUGH_DATA; // Truncated bitstream.
}
// Skip over CHUNK_HEADER_SIZE bytes from VP8/VP8L Header.
*chunk_size = size;
*data_ptr += CHUNK_HEADER_SIZE;
*data_size -= CHUNK_HEADER_SIZE;
*is_lossless = is_vp8l;
} else {
// Raw VP8/VP8L bitstream (no header).
*is_lossless = VP8LCheckSignature(data, *data_size);
*chunk_size = *data_size;
}
return VP8_STATUS_OK;
}
static WebPMuxError MuxSet(WebPMux* const mux, CHUNK_INDEX idx, uint32_t nth,
const WebPData* const data, int copy_data) {
WebPChunk chunk;
WebPMuxError err = WEBP_MUX_NOT_FOUND;
assert(mux != NULL);
assert(!IsWPI(kChunks[idx].id));
ChunkInit(&chunk);
SWITCH_ID_LIST(IDX_VP8X, &mux->vp8x_);
SWITCH_ID_LIST(IDX_ICCP, &mux->iccp_);
SWITCH_ID_LIST(IDX_LOOP, &mux->loop_);
SWITCH_ID_LIST(IDX_META, &mux->meta_);
if (idx == IDX_UNKNOWN && data->size_ > TAG_SIZE) {
// For raw-data unknown chunk, the first four bytes should be the tag to be
// used for the chunk.
const WebPData tmp = { data->bytes_ + TAG_SIZE, data->size_ - TAG_SIZE };
err = ChunkAssignData(&chunk, &tmp, copy_data, GetLE32(data->bytes_ + 0));
if (err == WEBP_MUX_OK)
err = ChunkSetNth(&chunk, &mux->unknown_, nth);
}
return err;
}
static ParseStatus ReadHeader(MemBuffer* const mem) {
const size_t min_size = RIFF_HEADER_SIZE + CHUNK_HEADER_SIZE;
uint32_t riff_size;
// Basic file level validation.
if (MemDataSize(mem) < min_size) return PARSE_NEED_MORE_DATA;
if (memcmp(GetBuffer(mem), "RIFF", CHUNK_SIZE_BYTES) ||
memcmp(GetBuffer(mem) + CHUNK_HEADER_SIZE, "WEBP", CHUNK_SIZE_BYTES)) {
return PARSE_ERROR;
}
riff_size = GetLE32(GetBuffer(mem) + TAG_SIZE);
if (riff_size < CHUNK_HEADER_SIZE) return PARSE_ERROR;
if (riff_size > MAX_CHUNK_PAYLOAD) return PARSE_ERROR;
// There's no point in reading past the end of the RIFF chunk
mem->riff_end_ = riff_size + CHUNK_HEADER_SIZE;
if (mem->buf_size_ > mem->riff_end_) {
mem->buf_size_ = mem->end_ = mem->riff_end_;
}
Skip(mem, RIFF_HEADER_SIZE);
return PARSE_OK;
}
static WEBP_INLINE uint32_t ReadLE32(MemBuffer* const mem) {
const uint8_t* const data = mem->buf_ + mem->start_;
const uint32_t val = GetLE32(data);
Skip(mem, 4);
return val;
}
// Skips to the next VP8/VP8L chunk header in the data given the size of the
// RIFF chunk 'riff_size'.
// Returns VP8_STATUS_BITSTREAM_ERROR if any invalid chunk size is encountered,
// VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
// VP8_STATUS_OK otherwise.
// If an alpha chunk is found, *alpha_data and *alpha_size are set
// appropriately.
static VP8StatusCode ParseOptionalChunks(const uint8_t** const data,
size_t* const data_size,
size_t const riff_size,
const uint8_t** const alpha_data,
size_t* const alpha_size) {
const uint8_t* buf;
size_t buf_size;
uint32_t total_size = TAG_SIZE + // "WEBP".
CHUNK_HEADER_SIZE + // "VP8Xnnnn".
VP8X_CHUNK_SIZE; // data.
assert(data != NULL);
assert(data_size != NULL);
buf = *data;
buf_size = *data_size;
assert(alpha_data != NULL);
assert(alpha_size != NULL);
*alpha_data = NULL;
*alpha_size = 0;
while (1) {
uint32_t chunk_size;
uint32_t disk_chunk_size; // chunk_size with padding
*data = buf;
*data_size = buf_size;
if (buf_size < CHUNK_HEADER_SIZE) { // Insufficient data.
return VP8_STATUS_NOT_ENOUGH_DATA;
}
chunk_size = GetLE32(buf + TAG_SIZE);
if (chunk_size > MAX_CHUNK_PAYLOAD) {
return VP8_STATUS_BITSTREAM_ERROR; // Not a valid chunk size.
}
// For odd-sized chunk-payload, there's one byte padding at the end.
disk_chunk_size = (CHUNK_HEADER_SIZE + chunk_size + 1) & ~1;
total_size += disk_chunk_size;
// Check that total bytes skipped so far does not exceed riff_size.
if (riff_size > 0 && (total_size > riff_size)) {
return VP8_STATUS_BITSTREAM_ERROR; // Not a valid chunk size.
}
// Start of a (possibly incomplete) VP8/VP8L chunk implies that we have
// parsed all the optional chunks.
// Note: This check must occur before the check 'buf_size < disk_chunk_size'
// below to allow incomplete VP8/VP8L chunks.
if (!memcmp(buf, "VP8 ", TAG_SIZE) ||
!memcmp(buf, "VP8L", TAG_SIZE)) {
return VP8_STATUS_OK;
}
if (buf_size < disk_chunk_size) { // Insufficient data.
return VP8_STATUS_NOT_ENOUGH_DATA;
}
if (!memcmp(buf, "ALPH", TAG_SIZE)) { // A valid ALPH header.
*alpha_data = buf + CHUNK_HEADER_SIZE;
*alpha_size = chunk_size;
}
// We have a full and valid chunk; skip it.
buf += disk_chunk_size;
buf_size -= disk_chunk_size;
}
}
WebPMux* WebPMuxCreateInternal(const WebPData* bitstream, int copy_data,
int version) {
size_t riff_size;
uint32_t tag;
const uint8_t* end;
WebPMux* mux = NULL;
WebPMuxImage* wpi = NULL;
const uint8_t* data;
size_t size;
WebPChunk chunk;
ChunkInit(&chunk);
// Sanity checks.
if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_MUX_ABI_VERSION)) {
return NULL; // version mismatch
}
if (bitstream == NULL) return NULL;
data = bitstream->bytes;
size = bitstream->size;
if (data == NULL) return NULL;
if (size < RIFF_HEADER_SIZE) return NULL;
if (GetLE32(data + 0) != MKFOURCC('R', 'I', 'F', 'F') ||
GetLE32(data + CHUNK_HEADER_SIZE) != MKFOURCC('W', 'E', 'B', 'P')) {
return NULL;
}
mux = WebPMuxNew();
if (mux == NULL) return NULL;
if (size < RIFF_HEADER_SIZE + TAG_SIZE) goto Err;
tag = GetLE32(data + RIFF_HEADER_SIZE);
if (tag != kChunks[IDX_VP8].tag &&
tag != kChunks[IDX_VP8L].tag &&
tag != kChunks[IDX_VP8X].tag) {
goto Err; // First chunk should be VP8, VP8L or VP8X.
}
riff_size = SizeWithPadding(GetLE32(data + TAG_SIZE));
if (riff_size > MAX_CHUNK_PAYLOAD || riff_size > size) {
goto Err;
} else {
if (riff_size < size) { // Redundant data after last chunk.
size = riff_size; // To make sure we don't read any data beyond mux_size.
}
}
end = data + size;
data += RIFF_HEADER_SIZE;
size -= RIFF_HEADER_SIZE;
wpi = (WebPMuxImage*)WebPSafeMalloc(1ULL, sizeof(*wpi));
if (wpi == NULL) goto Err;
MuxImageInit(wpi);
// Loop over chunks.
while (data != end) {
size_t data_size;
WebPChunkId id;
WebPChunk** chunk_list;
if (ChunkVerifyAndAssign(&chunk, data, size, riff_size,
copy_data) != WEBP_MUX_OK) {
goto Err;
}
data_size = ChunkDiskSize(&chunk);
id = ChunkGetIdFromTag(chunk.tag_);
switch (id) {
case WEBP_CHUNK_ALPHA:
if (wpi->alpha_ != NULL) goto Err; // Consecutive ALPH chunks.
if (ChunkSetNth(&chunk, &wpi->alpha_, 1) != WEBP_MUX_OK) goto Err;
wpi->is_partial_ = 1; // Waiting for a VP8 chunk.
break;
case WEBP_CHUNK_IMAGE:
if (ChunkSetNth(&chunk, &wpi->img_, 1) != WEBP_MUX_OK) goto Err;
if (!MuxImageFinalize(wpi)) goto Err;
wpi->is_partial_ = 0; // wpi is completely filled.
PushImage:
// Add this to mux->images_ list.
if (MuxImagePush(wpi, &mux->images_) != WEBP_MUX_OK) goto Err;
MuxImageInit(wpi); // Reset for reading next image.
break;
case WEBP_CHUNK_ANMF:
if (wpi->is_partial_) goto Err; // Previous wpi is still incomplete.
if (!MuxImageParse(&chunk, copy_data, wpi)) goto Err;
ChunkRelease(&chunk);
goto PushImage;
break;
default: // A non-image chunk.
if (wpi->is_partial_) goto Err; // Encountered a non-image chunk before
// getting all chunks of an image.
chunk_list = MuxGetChunkListFromId(mux, id); // List to add this chunk.
if (ChunkSetNth(&chunk, chunk_list, 0) != WEBP_MUX_OK) goto Err;
if (id == WEBP_CHUNK_VP8X) { // grab global specs
mux->canvas_width_ = GetLE24(data + 12) + 1;
mux->canvas_height_ = GetLE24(data + 15) + 1;
}
break;
}
data += data_size;
size -= data_size;
ChunkInit(&chunk);
}
// Validate mux if complete.
if (MuxValidate(mux) != WEBP_MUX_OK) goto Err;
MuxImageDelete(wpi);
return mux; // All OK;
Err: // Something bad happened.
ChunkRelease(&chunk);
MuxImageDelete(wpi);
WebPMuxDelete(mux);
return NULL;
}
static ParseStatus ParseVP8X(WebPDemuxer* const dmux) {
MemBuffer* const mem = &dmux->mem_;
int loop_chunks = 0;
uint32_t vp8x_size;
ParseStatus status = PARSE_OK;
if (MemDataSize(mem) < CHUNK_HEADER_SIZE) return PARSE_NEED_MORE_DATA;
dmux->is_ext_format_ = 1;
Skip(mem, TAG_SIZE); // VP8X
vp8x_size = GetLE32(mem);
if (vp8x_size > MAX_CHUNK_PAYLOAD) return PARSE_ERROR;
if (vp8x_size < VP8X_CHUNK_SIZE) return PARSE_ERROR;
vp8x_size += vp8x_size & 1;
if (SizeIsInvalid(mem, vp8x_size)) return PARSE_ERROR;
if (MemDataSize(mem) < vp8x_size) return PARSE_NEED_MORE_DATA;
dmux->feature_flags_ = GetByte(mem);
Skip(mem, 3); // Reserved.
dmux->canvas_width_ = 1 + GetLE24s(mem);
dmux->canvas_height_ = 1 + GetLE24s(mem);
if (dmux->canvas_width_ * (uint64_t)dmux->canvas_height_ >= MAX_IMAGE_AREA) {
return PARSE_ERROR; // image final dimension is too large
}
Skip(mem, vp8x_size - VP8X_CHUNK_SIZE); // skip any trailing data.
dmux->state_ = WEBP_DEMUX_PARSED_HEADER;
if (SizeIsInvalid(mem, CHUNK_HEADER_SIZE)) return PARSE_ERROR;
if (MemDataSize(mem) < CHUNK_HEADER_SIZE) return PARSE_NEED_MORE_DATA;
do {
int store_chunk = 1;
const size_t chunk_start_offset = mem->start_;
const uint32_t fourcc = GetLE32(mem);
const uint32_t chunk_size = GetLE32(mem);
const uint32_t chunk_size_padded = chunk_size + (chunk_size & 1);
if (chunk_size > MAX_CHUNK_PAYLOAD) return PARSE_ERROR;
if (SizeIsInvalid(mem, chunk_size_padded)) return PARSE_ERROR;
switch (fourcc) {
case MKFOURCC('V', 'P', '8', 'X'): {
return PARSE_ERROR;
}
case MKFOURCC('A', 'L', 'P', 'H'):
case MKFOURCC('V', 'P', '8', ' '):
case MKFOURCC('V', 'P', '8', 'L'): {
Rewind(mem, CHUNK_HEADER_SIZE);
status = ParseSingleImage(dmux);
break;
}
case MKFOURCC('L', 'O', 'O', 'P'): {
if (chunk_size_padded < LOOP_CHUNK_SIZE) return PARSE_ERROR;
if (MemDataSize(mem) < chunk_size_padded) {
status = PARSE_NEED_MORE_DATA;
} else if (loop_chunks == 0) {
++loop_chunks;
dmux->loop_count_ = GetLE16s(mem);
Skip(mem, chunk_size_padded - LOOP_CHUNK_SIZE);
} else {
store_chunk = 0;
goto Skip;
}
break;
}
case MKFOURCC('F', 'R', 'M', ' '): {
status = ParseFrame(dmux, chunk_size_padded);
break;
}
case MKFOURCC('T', 'I', 'L', 'E'): {
if (dmux->num_frames_ == 0) dmux->num_frames_ = 1;
status = ParseTile(dmux, chunk_size_padded);
break;
}
case MKFOURCC('I', 'C', 'C', 'P'): {
store_chunk = !!(dmux->feature_flags_ & ICCP_FLAG);
goto Skip;
}
case MKFOURCC('M', 'E', 'T', 'A'): {
store_chunk = !!(dmux->feature_flags_ & META_FLAG);
goto Skip;
}
Skip:
default: {
if (chunk_size_padded <= MemDataSize(mem)) {
if (store_chunk) {
// Store only the chunk header and unpadded size as only the payload
// will be returned to the user.
if (!StoreChunk(dmux, chunk_start_offset,
CHUNK_HEADER_SIZE + chunk_size)) {
return PARSE_ERROR;
}
}
Skip(mem, chunk_size_padded);
} else {
status = PARSE_NEED_MORE_DATA;
}
}
}
if (mem->start_ == mem->riff_end_) {
break;
} else if (MemDataSize(mem) < CHUNK_HEADER_SIZE) {
status = PARSE_NEED_MORE_DATA;
}
} while (status == PARSE_OK);
return status;
}
// Store image bearing chunks to 'frame'.
static ParseStatus StoreFrame(int frame_num, MemBuffer* const mem,
Frame* const frame) {
int alpha_chunks = 0;
int image_chunks = 0;
int done = (MemDataSize(mem) < CHUNK_HEADER_SIZE);
ParseStatus status = PARSE_OK;
if (done) return PARSE_NEED_MORE_DATA;
do {
const size_t chunk_start_offset = mem->start_;
const uint32_t fourcc = GetLE32(mem);
const uint32_t payload_size = GetLE32(mem);
const uint32_t payload_size_padded = payload_size + (payload_size & 1);
const size_t payload_available = (payload_size_padded > MemDataSize(mem))
? MemDataSize(mem) : payload_size_padded;
const size_t chunk_size = CHUNK_HEADER_SIZE + payload_available;
if (payload_size > MAX_CHUNK_PAYLOAD) return PARSE_ERROR;
if (SizeIsInvalid(mem, payload_size_padded)) return PARSE_ERROR;
if (payload_size_padded > MemDataSize(mem)) status = PARSE_NEED_MORE_DATA;
switch (fourcc) {
case MKFOURCC('A', 'L', 'P', 'H'):
if (alpha_chunks == 0) {
++alpha_chunks;
frame->img_components_[1].offset_ = chunk_start_offset;
frame->img_components_[1].size_ = chunk_size;
frame->frame_num_ = frame_num;
Skip(mem, payload_available);
} else {
goto Done;
}
break;
case MKFOURCC('V', 'P', '8', ' '):
case MKFOURCC('V', 'P', '8', 'L'):
if (image_chunks == 0) {
int width = 0, height = 0;
++image_chunks;
frame->img_components_[0].offset_ = chunk_start_offset;
frame->img_components_[0].size_ = chunk_size;
// Extract the width and height from the bitstream, tolerating
// failures when the data is incomplete.
if (!WebPGetInfo(mem->buf_ + frame->img_components_[0].offset_,
frame->img_components_[0].size_, &width, &height) &&
status != PARSE_NEED_MORE_DATA) {
return PARSE_ERROR;
}
frame->width_ = width;
frame->height_ = height;
frame->frame_num_ = frame_num;
frame->complete_ = (status == PARSE_OK);
Skip(mem, payload_available);
} else {
goto Done;
}
break;
Done:
default:
// Restore fourcc/size when moving up one level in parsing.
Rewind(mem, CHUNK_HEADER_SIZE);
done = 1;
break;
}
if (mem->start_ == mem->riff_end_) {
done = 1;
} else if (MemDataSize(mem) < CHUNK_HEADER_SIZE) {
status = PARSE_NEED_MORE_DATA;
}
} while (!done && status == PARSE_OK);
return status;
}
