// Assemble a single image WebP bitstream from 'wpi'.
static WebPMuxError SynthesizeBitstream(const WebPMuxImage* const wpi,
WebPData* const bitstream) {
uint8_t* dst;
// Allocate data.
const int need_vp8x = (wpi->alpha_ != NULL);
const size_t vp8x_size = need_vp8x ? CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE : 0;
const size_t alpha_size = need_vp8x ? ChunkDiskSize(wpi->alpha_) : 0;
// Note: No need to output ANMF/FRGM chunk for a single image.
const size_t size = RIFF_HEADER_SIZE + vp8x_size + alpha_size +
ChunkDiskSize(wpi->img_);
uint8_t* const data = (uint8_t*)WebPSafeMalloc(1ULL, size);
if (data == NULL) return WEBP_MUX_MEMORY_ERROR;
// Main RIFF header.
dst = MuxEmitRiffHeader(data, size);
if (need_vp8x) {
dst = EmitVP8XChunk(dst, wpi->width_, wpi->height_, ALPHA_FLAG); // VP8X.
dst = ChunkListEmit(wpi->alpha_, dst); // ALPH.
}
// Bitstream.
dst = ChunkListEmit(wpi->img_, dst);
assert(dst == data + size);
// Output.
bitstream->bytes = data;
bitstream->size = size;
return WEBP_MUX_OK;
}
// Size of an image.
size_t MuxImageDiskSize(const WebPMuxImage* const wpi) {
size_t size = 0;
if (wpi->header_ != NULL) size += ChunkDiskSize(wpi->header_);
if (wpi->alpha_ != NULL) size += ChunkDiskSize(wpi->alpha_);
if (wpi->img_ != NULL) size += ChunkDiskSize(wpi->img_);
return size;
}
size_t ChunkListDiskSize(const WebPChunk* chunk_list) {
size_t size = 0;
while (chunk_list != NULL) {
size += ChunkDiskSize(chunk_list);
chunk_list = chunk_list->next_;
}
return size;
}
static uint8_t* ChunkEmit(const WebPChunk* const chunk, uint8_t* dst) {
const size_t chunk_size = chunk->data_.size;
assert(chunk);
assert(chunk->tag_ != NIL_TAG);
PutLE32(dst + 0, chunk->tag_);
PutLE32(dst + TAG_SIZE, (uint32_t)chunk_size);
assert(chunk_size == (uint32_t)chunk_size);
memcpy(dst + CHUNK_HEADER_SIZE, chunk->data_.bytes, chunk_size);
if (chunk_size & 1)
dst[CHUNK_HEADER_SIZE + chunk_size] = 0; // Add padding.
return dst + ChunkDiskSize(chunk);
}
// Special case as ANMF/FRGM chunk encapsulates other image chunks.
static uint8_t* ChunkEmitSpecial(const WebPChunk* const header,
size_t total_size, uint8_t* dst) {
const size_t header_size = header->data_.size;
const size_t offset_to_next = total_size - CHUNK_HEADER_SIZE;
assert(header->tag_ == kChunks[IDX_ANMF].tag ||
header->tag_ == kChunks[IDX_FRGM].tag);
PutLE32(dst + 0, header->tag_);
PutLE32(dst + TAG_SIZE, (uint32_t)offset_to_next);
assert(header_size == (uint32_t)header_size);
memcpy(dst + CHUNK_HEADER_SIZE, header->data_.bytes, header_size);
if (header_size & 1) {
dst[CHUNK_HEADER_SIZE + header_size] = 0; // Add padding.
}
return dst + ChunkDiskSize(header);
}
static int MuxImageParse(const WebPChunk* const chunk, int copy_data,
WebPMuxImage* const wpi) {
const uint8_t* bytes = chunk->data_.bytes;
size_t size = chunk->data_.size;
const uint8_t* const last = bytes + size;
WebPChunk subchunk;
size_t subchunk_size;
ChunkInit(&subchunk);
assert(chunk->tag_ == kChunks[IDX_ANMF].tag ||
chunk->tag_ == kChunks[IDX_FRGM].tag);
assert(!wpi->is_partial_);
// ANMF/FRGM.
{
const size_t hdr_size = (chunk->tag_ == kChunks[IDX_ANMF].tag) ?
ANMF_CHUNK_SIZE : FRGM_CHUNK_SIZE;
const WebPData temp = { bytes, hdr_size };
// Each of ANMF and FRGM chunk contain a header at the beginning. So, its
// size should at least be 'hdr_size'.
if (size < hdr_size) goto Fail;
ChunkAssignData(&subchunk, &temp, copy_data, chunk->tag_);
}
ChunkSetNth(&subchunk, &wpi->header_, 1);
wpi->is_partial_ = 1; // Waiting for ALPH and/or VP8/VP8L chunks.
// Rest of the chunks.
subchunk_size = ChunkDiskSize(&subchunk) - CHUNK_HEADER_SIZE;
bytes += subchunk_size;
size -= subchunk_size;
while (bytes != last) {
ChunkInit(&subchunk);
if (ChunkVerifyAndAssign(&subchunk, bytes, size, size,
copy_data) != WEBP_MUX_OK) {
goto Fail;
}
switch (ChunkGetIdFromTag(subchunk.tag_)) {
case WEBP_CHUNK_ALPHA:
if (wpi->alpha_ != NULL) goto Fail; // Consecutive ALPH chunks.
if (ChunkSetNth(&subchunk, &wpi->alpha_, 1) != WEBP_MUX_OK) goto Fail;
wpi->is_partial_ = 1; // Waiting for a VP8 chunk.
break;
case WEBP_CHUNK_IMAGE:
if (ChunkSetNth(&subchunk, &wpi->img_, 1) != WEBP_MUX_OK) goto Fail;
if (!MuxImageFinalize(wpi)) goto Fail;
wpi->is_partial_ = 0; // wpi is completely filled.
break;
case WEBP_CHUNK_UNKNOWN:
if (wpi->is_partial_) goto Fail; // Encountered an unknown chunk
// before some image chunks.
if (ChunkSetNth(&subchunk, &wpi->unknown_, 0) != WEBP_MUX_OK) goto Fail;
break;
default:
goto Fail;
break;
}
subchunk_size = ChunkDiskSize(&subchunk);
bytes += subchunk_size;
size -= subchunk_size;
}
if (wpi->is_partial_) goto Fail;
return 1;
Fail:
ChunkRelease(&subchunk);
return 0;
}
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;
}
