blob: 547a7725dee939b122ecf5eec321fb08e6416212 [file] [log] [blame]
// Copyright 2012 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// WebP container demux.
//
#ifdef HAVE_CONFIG_H
#include "src/webp/config.h"
#endif
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "src/utils/utils.h"
#include "src/webp/decode.h" // WebPGetFeatures
#include "src/webp/demux.h"
#include "src/webp/format_constants.h"
#define DMUX_MAJ_VERSION 1
#define DMUX_MIN_VERSION 2
#define DMUX_REV_VERSION 1
typedef struct {
size_t start_; // start location of the data
size_t end_; // end location
size_t riff_end_; // riff chunk end location, can be > end_.
size_t buf_size_; // size of the buffer
const uint8_t* buf_;
} MemBuffer;
typedef struct {
size_t offset_;
size_t size_;
} ChunkData;
typedef struct Frame {
int x_offset_, y_offset_;
int width_, height_;
int has_alpha_;
int duration_;
WebPMuxAnimDispose dispose_method_;
WebPMuxAnimBlend blend_method_;
int frame_num_;
int complete_; // img_components_ contains a full image.
ChunkData img_components_[2]; // 0=VP8{,L} 1=ALPH
struct Frame* next_;
} Frame;
typedef struct Chunk {
ChunkData data_;
struct Chunk* next_;
} Chunk;
struct WebPDemuxer {
MemBuffer mem_;
WebPDemuxState state_;
int is_ext_format_;
uint32_t feature_flags_;
int canvas_width_, canvas_height_;
int loop_count_;
uint32_t bgcolor_;
int num_frames_;
Frame* frames_;
Frame** frames_tail_;
Chunk* chunks_; // non-image chunks
Chunk** chunks_tail_;
};
typedef enum {
PARSE_OK,
PARSE_NEED_MORE_DATA,
PARSE_ERROR
} ParseStatus;
typedef struct ChunkParser {
uint8_t id[4];
ParseStatus (*parse)(WebPDemuxer* const dmux);
int (*valid)(const WebPDemuxer* const dmux);
} ChunkParser;
static ParseStatus ParseSingleImage(WebPDemuxer* const dmux);
static ParseStatus ParseVP8X(WebPDemuxer* const dmux);
static int IsValidSimpleFormat(const WebPDemuxer* const dmux);
static int IsValidExtendedFormat(const WebPDemuxer* const dmux);
static const ChunkParser kMasterChunks[] = {
{ { 'V', 'P', '8', ' ' }, ParseSingleImage, IsValidSimpleFormat },
{ { 'V', 'P', '8', 'L' }, ParseSingleImage, IsValidSimpleFormat },
{ { 'V', 'P', '8', 'X' }, ParseVP8X, IsValidExtendedFormat },
{ { '0', '0', '0', '0' }, NULL, NULL },
};
//------------------------------------------------------------------------------
int WebPGetDemuxVersion(void) {
return (DMUX_MAJ_VERSION << 16) | (DMUX_MIN_VERSION << 8) | DMUX_REV_VERSION;
}
// -----------------------------------------------------------------------------
// MemBuffer
static int RemapMemBuffer(MemBuffer* const mem,
const uint8_t* data, size_t size) {
if (size < mem->buf_size_) return 0; // can't remap to a shorter buffer!
mem->buf_ = data;
mem->end_ = mem->buf_size_ = size;
return 1;
}
static int InitMemBuffer(MemBuffer* const mem,
const uint8_t* data, size_t size) {
memset(mem, 0, sizeof(*mem));
return RemapMemBuffer(mem, data, size);
}
// Return the remaining data size available in 'mem'.
static WEBP_INLINE size_t MemDataSize(const MemBuffer* const mem) {
return (mem->end_ - mem->start_);
}
// Return true if 'size' exceeds the end of the RIFF chunk.
static WEBP_INLINE int SizeIsInvalid(const MemBuffer* const mem, size_t size) {
return (size > mem->riff_end_ - mem->start_);
}
static WEBP_INLINE void Skip(MemBuffer* const mem, size_t size) {
mem->start_ += size;
}
static WEBP_INLINE void Rewind(MemBuffer* const mem, size_t size) {
mem->start_ -= size;
}
static WEBP_INLINE const uint8_t* GetBuffer(MemBuffer* const mem) {
return mem->buf_ + mem->start_;
}
// Read from 'mem' and skip the read bytes.
static WEBP_INLINE uint8_t ReadByte(MemBuffer* const mem) {
const uint8_t byte = mem->buf_[mem->start_];
Skip(mem, 1);
return byte;
}
static WEBP_INLINE int ReadLE16s(MemBuffer* const mem) {
const uint8_t* const data = mem->buf_ + mem->start_;
const int val = GetLE16(data);
Skip(mem, 2);
return val;
}
static WEBP_INLINE int ReadLE24s(MemBuffer* const mem) {
const uint8_t* const data = mem->buf_ + mem->start_;
const int val = GetLE24(data);
Skip(mem, 3);
return val;
}
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;
}
// -----------------------------------------------------------------------------
// Secondary chunk parsing
static void AddChunk(WebPDemuxer* const dmux, Chunk* const chunk) {
*dmux->chunks_tail_ = chunk;
chunk->next_ = NULL;
dmux->chunks_tail_ = &chunk->next_;
}
// Add a frame to the end of the list, ensuring the last frame is complete.
// Returns true on success, false otherwise.
static int AddFrame(WebPDemuxer* const dmux, Frame* const frame) {
const Frame* const last_frame = *dmux->frames_tail_;
if (last_frame != NULL && !last_frame->complete_) return 0;
*dmux->frames_tail_ = frame;
frame->next_ = NULL;
dmux->frames_tail_ = &frame->next_;
return 1;
}
static void SetFrameInfo(size_t start_offset, size_t size,
int frame_num, int complete,
const WebPBitstreamFeatures* const features,
Frame* const frame) {
frame->img_components_[0].offset_ = start_offset;
frame->img_components_[0].size_ = size;
frame->width_ = features->width;
frame->height_ = features->height;
frame->has_alpha_ |= features->has_alpha;
frame->frame_num_ = frame_num;
frame->complete_ = complete;
}
// Store image bearing chunks to 'frame'. 'min_size' is an optional size
// requirement, it may be zero.
static ParseStatus StoreFrame(int frame_num, uint32_t min_size,
MemBuffer* const mem, Frame* const frame) {
int alpha_chunks = 0;
int image_chunks = 0;
int done = (MemDataSize(mem) < CHUNK_HEADER_SIZE ||
MemDataSize(mem) < min_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 = ReadLE32(mem);
const uint32_t payload_size = ReadLE32(mem);
uint32_t payload_size_padded;
size_t payload_available;
size_t chunk_size;
if (payload_size > MAX_CHUNK_PAYLOAD) return PARSE_ERROR;
payload_size_padded = payload_size + (payload_size & 1);
payload_available = (payload_size_padded > MemDataSize(mem))
? MemDataSize(mem) : payload_size_padded;
chunk_size = CHUNK_HEADER_SIZE + payload_available;
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->has_alpha_ = 1;
frame->frame_num_ = frame_num;
Skip(mem, payload_available);
} else {
goto Done;
}
break;
case MKFOURCC('V', 'P', '8', 'L'):
if (alpha_chunks > 0) return PARSE_ERROR; // VP8L has its own alpha
// fall through
case MKFOURCC('V', 'P', '8', ' '):
if (image_chunks == 0) {
// Extract the bitstream features, tolerating failures when the data
// is incomplete.
WebPBitstreamFeatures features;
const VP8StatusCode vp8_status =
WebPGetFeatures(mem->buf_ + chunk_start_offset, chunk_size,
&features);
if (status == PARSE_NEED_MORE_DATA &&
vp8_status == VP8_STATUS_NOT_ENOUGH_DATA) {
return PARSE_NEED_MORE_DATA;
} else if (vp8_status != VP8_STATUS_OK) {
// We have enough data, and yet WebPGetFeatures() failed.
return PARSE_ERROR;
}
++image_chunks;
SetFrameInfo(chunk_start_offset, chunk_size, frame_num,
status == PARSE_OK, &features, frame);
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;
}
// Creates a new Frame if 'actual_size' is within bounds and 'mem' contains
// enough data ('min_size') to parse the payload.
// Returns PARSE_OK on success with *frame pointing to the new Frame.
// Returns PARSE_NEED_MORE_DATA with insufficient data, PARSE_ERROR otherwise.
static ParseStatus NewFrame(const MemBuffer* const mem,
uint32_t min_size, uint32_t actual_size,
Frame** frame) {
if (SizeIsInvalid(mem, min_size)) return PARSE_ERROR;
if (actual_size < min_size) return PARSE_ERROR;
if (MemDataSize(mem) < min_size) return PARSE_NEED_MORE_DATA;
*frame = (Frame*)WebPSafeCalloc(1ULL, sizeof(**frame));
return (*frame == NULL) ? PARSE_ERROR : PARSE_OK;
}
// Parse a 'ANMF' chunk and any image bearing chunks that immediately follow.
// 'frame_chunk_size' is the previously validated, padded chunk size.
static ParseStatus ParseAnimationFrame(
WebPDemuxer* const dmux, uint32_t frame_chunk_size) {
const int is_animation = !!(dmux->feature_flags_ & ANIMATION_FLAG);
const uint32_t anmf_payload_size = frame_chunk_size - ANMF_CHUNK_SIZE;
int added_frame = 0;
int bits;
MemBuffer* const mem = &dmux->mem_;
Frame* frame;
size_t start_offset;
ParseStatus status =
NewFrame(mem, ANMF_CHUNK_SIZE, frame_chunk_size, &frame);
if (status != PARSE_OK) return status;
frame->x_offset_ = 2 * ReadLE24s(mem);
frame->y_offset_ = 2 * ReadLE24s(mem);
frame->width_ = 1 + ReadLE24s(mem);
frame->height_ = 1 + ReadLE24s(mem);
frame->duration_ = ReadLE24s(mem);
bits = ReadByte(mem);
frame->dispose_method_ =
(bits & 1) ? WEBP_MUX_DISPOSE_BACKGROUND : WEBP_MUX_DISPOSE_NONE;
frame->blend_method_ = (bits & 2) ? WEBP_MUX_NO_BLEND : WEBP_MUX_BLEND;
if (frame->width_ * (uint64_t)frame->height_ >= MAX_IMAGE_AREA) {
WebPSafeFree(frame);
return PARSE_ERROR;
}
// Store a frame only if the animation flag is set there is some data for
// this frame is available.
start_offset = mem->start_;
status = StoreFrame(dmux->num_frames_ + 1, anmf_payload_size, mem, frame);
if (status != PARSE_ERROR && mem->start_ - start_offset > anmf_payload_size) {
status = PARSE_ERROR;
}
if (status != PARSE_ERROR && is_animation && frame->frame_num_ > 0) {
added_frame = AddFrame(dmux, frame);
if (added_frame) {
++dmux->num_frames_;
} else {
status = PARSE_ERROR;
}
}
if (!added_frame) WebPSafeFree(frame);
return status;
}
// General chunk storage, starting with the header at 'start_offset', allowing
// the user to request the payload via a fourcc string. 'size' includes the
// header and the unpadded payload size.
// Returns true on success, false otherwise.
static int StoreChunk(WebPDemuxer* const dmux,
size_t start_offset, uint32_t size) {
Chunk* const chunk = (Chunk*)WebPSafeCalloc(1ULL, sizeof(*chunk));
if (chunk == NULL) return 0;
chunk->data_.offset_ = start_offset;
chunk->data_.size_ = size;
AddChunk(dmux, chunk);
return 1;
}
// -----------------------------------------------------------------------------
// Primary chunk parsing
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 ParseStatus ParseSingleImage(WebPDemuxer* const dmux) {
const size_t min_size = CHUNK_HEADER_SIZE;
MemBuffer* const mem = &dmux->mem_;
Frame* frame;
ParseStatus status;
int image_added = 0;
if (dmux->frames_ != NULL) return PARSE_ERROR;
if (SizeIsInvalid(mem, min_size)) return PARSE_ERROR;
if (MemDataSize(mem) < min_size) return PARSE_NEED_MORE_DATA;
frame = (Frame*)WebPSafeCalloc(1ULL, sizeof(*frame));
if (frame == NULL) return PARSE_ERROR;
// For the single image case we allow parsing of a partial frame, so no
// minimum size is imposed here.
status = StoreFrame(1, 0, &dmux->mem_, frame);
if (status != PARSE_ERROR) {
const int has_alpha = !!(dmux->feature_flags_ & ALPHA_FLAG);
// Clear any alpha when the alpha flag is missing.
if (!has_alpha && frame->img_components_[1].size_ > 0) {
frame->img_components_[1].offset_ = 0;
frame->img_components_[1].size_ = 0;
frame->has_alpha_ = 0;
}
// Use the frame width/height as the canvas values for non-vp8x files.
// Also, set ALPHA_FLAG if this is a lossless image with alpha.
if (!dmux->is_ext_format_ && frame->width_ > 0 && frame->height_ > 0) {
dmux->state_ = WEBP_DEMUX_PARSED_HEADER;
dmux->canvas_width_ = frame->width_;
dmux->canvas_height_ = frame->height_;
dmux->feature_flags_ |= frame->has_alpha_ ? ALPHA_FLAG : 0;
}
if (!AddFrame(dmux, frame)) {
status = PARSE_ERROR; // last frame was left incomplete
} else {
image_added = 1;
dmux->num_frames_ = 1;
}
}
if (!image_added) WebPSafeFree(frame);
return status;
}
static ParseStatus ParseVP8XChunks(WebPDemuxer* const dmux) {
const int is_animation = !!(dmux->feature_flags_ & ANIMATION_FLAG);
MemBuffer* const mem = &dmux->mem_;
int anim_chunks = 0;
ParseStatus status = PARSE_OK;
do {
int store_chunk = 1;
const size_t chunk_start_offset = mem->start_;
const uint32_t fourcc = ReadLE32(mem);
const uint32_t chunk_size = ReadLE32(mem);
uint32_t chunk_size_padded;
if (chunk_size > MAX_CHUNK_PAYLOAD) return PARSE_ERROR;
chunk_size_padded = chunk_size + (chunk_size & 1);
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'): {
// check that this isn't an animation (all frames should be in an ANMF).
if (anim_chunks > 0 || is_animation) return PARSE_ERROR;
Rewind(mem, CHUNK_HEADER_SIZE);
status = ParseSingleImage(dmux);
break;
}
case MKFOURCC('A', 'N', 'I', 'M'): {
if (chunk_size_padded < ANIM_CHUNK_SIZE) return PARSE_ERROR;
if (MemDataSize(mem) < chunk_size_padded) {
status = PARSE_NEED_MORE_DATA;
} else if (anim_chunks == 0) {
++anim_chunks;
dmux->bgcolor_ = ReadLE32(mem);
dmux->loop_count_ = ReadLE16s(mem);
Skip(mem, chunk_size_padded - ANIM_CHUNK_SIZE);
} else {
store_chunk = 0;
goto Skip;
}
break;
}
case MKFOURCC('A', 'N', 'M', 'F'): {
if (anim_chunks == 0) return PARSE_ERROR; // 'ANIM' precedes frames.
status = ParseAnimationFrame(dmux, chunk_size_padded);
break;
}
case MKFOURCC('I', 'C', 'C', 'P'): {
store_chunk = !!(dmux->feature_flags_ & ICCP_FLAG);
goto Skip;
}
case MKFOURCC('E', 'X', 'I', 'F'): {
store_chunk = !!(dmux->feature_flags_ & EXIF_FLAG);
goto Skip;
}
case MKFOURCC('X', 'M', 'P', ' '): {
store_chunk = !!(dmux->feature_flags_ & XMP_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;
}
static ParseStatus ParseVP8X(WebPDemuxer* const dmux) {
MemBuffer* const mem = &dmux->mem_;
uint32_t vp8x_size;
if (MemDataSize(mem) < CHUNK_HEADER_SIZE) return PARSE_NEED_MORE_DATA;
dmux->is_ext_format_ = 1;
Skip(mem, TAG_SIZE); // VP8X
vp8x_size = ReadLE32(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_ = ReadByte(mem);
Skip(mem, 3); // Reserved.
dmux->canvas_width_ = 1 + ReadLE24s(mem);
dmux->canvas_height_ = 1 + ReadLE24s(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;
return ParseVP8XChunks(dmux);
}
// -----------------------------------------------------------------------------
// Format validation
static int IsValidSimpleFormat(const WebPDemuxer* const dmux) {
const Frame* const frame = dmux->frames_;
if (dmux->state_ == WEBP_DEMUX_PARSING_HEADER) return 1;
if (dmux->canvas_width_ <= 0 || dmux->canvas_height_ <= 0) return 0;
if (dmux->state_ == WEBP_DEMUX_DONE && frame == NULL) return 0;
if (frame->width_ <= 0 || frame->height_ <= 0) return 0;
return 1;
}
// If 'exact' is true, check that the image resolution matches the canvas.
// If 'exact' is false, check that the x/y offsets do not exceed the canvas.
static int CheckFrameBounds(const Frame* const frame, int exact,
int canvas_width, int canvas_height) {
if (exact) {
if (frame->x_offset_ != 0 || frame->y_offset_ != 0) {
return 0;
}
if (frame->width_ != canvas_width || frame->height_ != canvas_height) {
return 0;
}
} else {
if (frame->x_offset_ < 0 || frame->y_offset_ < 0) return 0;
if (frame->width_ + frame->x_offset_ > canvas_width) return 0;
if (frame->height_ + frame->y_offset_ > canvas_height) return 0;
}
return 1;
}
static int IsValidExtendedFormat(const WebPDemuxer* const dmux) {
const int is_animation = !!(dmux->feature_flags_ & ANIMATION_FLAG);
const Frame* f = dmux->frames_;
if (dmux->state_ == WEBP_DEMUX_PARSING_HEADER) return 1;
if (dmux->canvas_width_ <= 0 || dmux->canvas_height_ <= 0) return 0;
if (dmux->loop_count_ < 0) return 0;
if (dmux->state_ == WEBP_DEMUX_DONE && dmux->frames_ == NULL) return 0;
if (dmux->feature_flags_ & ~ALL_VALID_FLAGS) return 0; // invalid bitstream
while (f != NULL) {
const int cur_frame_set = f->frame_num_;
int frame_count = 0;
// Check frame properties.
for (; f != NULL && f->frame_num_ == cur_frame_set; f = f->next_) {
const ChunkData* const image = f->img_components_;
const ChunkData* const alpha = f->img_components_ + 1;
if (!is_animation && f->frame_num_ > 1) return 0;
if (f->complete_) {
if (alpha->size_ == 0 && image->size_ == 0) return 0;
// Ensure alpha precedes image bitstream.
if (alpha->size_ > 0 && alpha->offset_ > image->offset_) {
return 0;
}
if (f->width_ <= 0 || f->height_ <= 0) return 0;
} else {
// There shouldn't be a partial frame in a complete file.
if (dmux->state_ == WEBP_DEMUX_DONE) return 0;
// Ensure alpha precedes image bitstream.
if (alpha->size_ > 0 && image->size_ > 0 &&
alpha->offset_ > image->offset_) {
return 0;
}
// There shouldn't be any frames after an incomplete one.
if (f->next_ != NULL) return 0;
}
if (f->width_ > 0 && f->height_ > 0 &&
!CheckFrameBounds(f, !is_animation,
dmux->canvas_width_, dmux->canvas_height_)) {
return 0;
}
++frame_count;
}
}
return 1;
}
// -----------------------------------------------------------------------------
// WebPDemuxer object
static void InitDemux(WebPDemuxer* const dmux, const MemBuffer* const mem) {
dmux->state_ = WEBP_DEMUX_PARSING_HEADER;
dmux->loop_count_ = 1;
dmux->bgcolor_ = 0xFFFFFFFF; // White background by default.
dmux->canvas_width_ = -1;
dmux->canvas_height_ = -1;
dmux->frames_tail_ = &dmux->frames_;
dmux->chunks_tail_ = &dmux->chunks_;
dmux->mem_ = *mem;
}
static ParseStatus CreateRawImageDemuxer(MemBuffer* const mem,
WebPDemuxer** demuxer) {
WebPBitstreamFeatures features;
const VP8StatusCode status =
WebPGetFeatures(mem->buf_, mem->buf_size_, &features);
*demuxer = NULL;
if (status != VP8_STATUS_OK) {
return (status == VP8_STATUS_NOT_ENOUGH_DATA) ? PARSE_NEED_MORE_DATA
: PARSE_ERROR;
}
{
WebPDemuxer* const dmux = (WebPDemuxer*)WebPSafeCalloc(1ULL, sizeof(*dmux));
Frame* const frame = (Frame*)WebPSafeCalloc(1ULL, sizeof(*frame));
if (dmux == NULL || frame == NULL) goto Error;
InitDemux(dmux, mem);
SetFrameInfo(0, mem->buf_size_, 1 /*frame_num*/, 1 /*complete*/, &features,
frame);
if (!AddFrame(dmux, frame)) goto Error;
dmux->state_ = WEBP_DEMUX_DONE;
dmux->canvas_width_ = frame->width_;
dmux->canvas_height_ = frame->height_;
dmux->feature_flags_ |= frame->has_alpha_ ? ALPHA_FLAG : 0;
dmux->num_frames_ = 1;
assert(IsValidSimpleFormat(dmux));
*demuxer = dmux;
return PARSE_OK;
Error:
WebPSafeFree(dmux);
WebPSafeFree(frame);
return PARSE_ERROR;
}
}
WebPDemuxer* WebPDemuxInternal(const WebPData* data, int allow_partial,
WebPDemuxState* state, int version) {
const ChunkParser* parser;
int partial;
ParseStatus status = PARSE_ERROR;
MemBuffer mem;
WebPDemuxer* dmux;
if (state != NULL) *state = WEBP_DEMUX_PARSE_ERROR;
if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DEMUX_ABI_VERSION)) return NULL;
if (data == NULL || data->bytes == NULL || data->size == 0) return NULL;
if (!InitMemBuffer(&mem, data->bytes, data->size)) return NULL;
status = ReadHeader(&mem);
if (status != PARSE_OK) {
// If parsing of the webp file header fails attempt to handle a raw
// VP8/VP8L frame. Note 'allow_partial' is ignored in this case.
if (status == PARSE_ERROR) {
status = CreateRawImageDemuxer(&mem, &dmux);
if (status == PARSE_OK) {
if (state != NULL) *state = WEBP_DEMUX_DONE;
return dmux;
}
}
if (state != NULL) {
*state = (status == PARSE_NEED_MORE_DATA) ? WEBP_DEMUX_PARSING_HEADER
: WEBP_DEMUX_PARSE_ERROR;
}
return NULL;
}
partial = (mem.buf_size_ < mem.riff_end_);
if (!allow_partial && partial) return NULL;
dmux = (WebPDemuxer*)WebPSafeCalloc(1ULL, sizeof(*dmux));
if (dmux == NULL) return NULL;
InitDemux(dmux, &mem);
status = PARSE_ERROR;
for (parser = kMasterChunks; parser->parse != NULL; ++parser) {
if (!memcmp(parser->id, GetBuffer(&dmux->mem_), TAG_SIZE)) {
status = parser->parse(dmux);
if (status == PARSE_OK) dmux->state_ = WEBP_DEMUX_DONE;
if (status == PARSE_NEED_MORE_DATA && !partial) status = PARSE_ERROR;
if (status != PARSE_ERROR && !parser->valid(dmux)) status = PARSE_ERROR;
if (status == PARSE_ERROR) dmux->state_ = WEBP_DEMUX_PARSE_ERROR;
break;
}
}
if (state != NULL) *state = dmux->state_;
if (status == PARSE_ERROR) {
WebPDemuxDelete(dmux);
return NULL;
}
return dmux;
}
void WebPDemuxDelete(WebPDemuxer* dmux) {
Chunk* c;
Frame* f;
if (dmux == NULL) return;
for (f = dmux->frames_; f != NULL;) {
Frame* const cur_frame = f;
f = f->next_;
WebPSafeFree(cur_frame);
}
for (c = dmux->chunks_; c != NULL;) {
Chunk* const cur_chunk = c;
c = c->next_;
WebPSafeFree(cur_chunk);
}
WebPSafeFree(dmux);
}
// -----------------------------------------------------------------------------
uint32_t WebPDemuxGetI(const WebPDemuxer* dmux, WebPFormatFeature feature) {
if (dmux == NULL) return 0;
switch (feature) {
case WEBP_FF_FORMAT_FLAGS: return dmux->feature_flags_;
case WEBP_FF_CANVAS_WIDTH: return (uint32_t)dmux->canvas_width_;
case WEBP_FF_CANVAS_HEIGHT: return (uint32_t)dmux->canvas_height_;
case WEBP_FF_LOOP_COUNT: return (uint32_t)dmux->loop_count_;
case WEBP_FF_BACKGROUND_COLOR: return dmux->bgcolor_;
case WEBP_FF_FRAME_COUNT: return (uint32_t)dmux->num_frames_;
}
return 0;
}
// -----------------------------------------------------------------------------
// Frame iteration
static const Frame* GetFrame(const WebPDemuxer* const dmux, int frame_num) {
const Frame* f;
for (f = dmux->frames_; f != NULL; f = f->next_) {
if (frame_num == f->frame_num_) break;
}
return f;
}
static const uint8_t* GetFramePayload(const uint8_t* const mem_buf,
const Frame* const frame,
size_t* const data_size) {
*data_size = 0;
if (frame != NULL) {
const ChunkData* const image = frame->img_components_;
const ChunkData* const alpha = frame->img_components_ + 1;
size_t start_offset = image->offset_;
*data_size = image->size_;
// if alpha exists it precedes image, update the size allowing for
// intervening chunks.
if (alpha->size_ > 0) {
const size_t inter_size = (image->offset_ > 0)
? image->offset_ - (alpha->offset_ + alpha->size_)
: 0;
start_offset = alpha->offset_;
*data_size += alpha->size_ + inter_size;
}
return mem_buf + start_offset;
}
return NULL;
}
// Create a whole 'frame' from VP8 (+ alpha) or lossless.
static int SynthesizeFrame(const WebPDemuxer* const dmux,
const Frame* const frame,
WebPIterator* const iter) {
const uint8_t* const mem_buf = dmux->mem_.buf_;
size_t payload_size = 0;
const uint8_t* const payload = GetFramePayload(mem_buf, frame, &payload_size);
if (payload == NULL) return 0;
assert(frame != NULL);
iter->frame_num = frame->frame_num_;
iter->num_frames = dmux->num_frames_;
iter->x_offset = frame->x_offset_;
iter->y_offset = frame->y_offset_;
iter->width = frame->width_;
iter->height = frame->height_;
iter->has_alpha = frame->has_alpha_;
iter->duration = frame->duration_;
iter->dispose_method = frame->dispose_method_;
iter->blend_method = frame->blend_method_;
iter->complete = frame->complete_;
iter->fragment.bytes = payload;
iter->fragment.size = payload_size;
return 1;
}
static int SetFrame(int frame_num, WebPIterator* const iter) {
const Frame* frame;
const WebPDemuxer* const dmux = (WebPDemuxer*)iter->private_;
if (dmux == NULL || frame_num < 0) return 0;
if (frame_num > dmux->num_frames_) return 0;
if (frame_num == 0) frame_num = dmux->num_frames_;
frame = GetFrame(dmux, frame_num);
if (frame == NULL) return 0;
return SynthesizeFrame(dmux, frame, iter);
}
int WebPDemuxGetFrame(const WebPDemuxer* dmux, int frame, WebPIterator* iter) {
if (iter == NULL) return 0;
memset(iter, 0, sizeof(*iter));
iter->private_ = (void*)dmux;
return SetFrame(frame, iter);
}
int WebPDemuxNextFrame(WebPIterator* iter) {
if (iter == NULL) return 0;
return SetFrame(iter->frame_num + 1, iter);
}
int WebPDemuxPrevFrame(WebPIterator* iter) {
if (iter == NULL) return 0;
if (iter->frame_num <= 1) return 0;
return SetFrame(iter->frame_num - 1, iter);
}
void WebPDemuxReleaseIterator(WebPIterator* iter) {
(void)iter;
}
// -----------------------------------------------------------------------------
// Chunk iteration
static int ChunkCount(const WebPDemuxer* const dmux, const char fourcc[4]) {
const uint8_t* const mem_buf = dmux->mem_.buf_;
const Chunk* c;
int count = 0;
for (c = dmux->chunks_; c != NULL; c = c->next_) {
const uint8_t* const header = mem_buf + c->data_.offset_;
if (!memcmp(header, fourcc, TAG_SIZE)) ++count;
}
return count;
}
static const Chunk* GetChunk(const WebPDemuxer* const dmux,
const char fourcc[4], int chunk_num) {
const uint8_t* const mem_buf = dmux->mem_.buf_;
const Chunk* c;
int count = 0;
for (c = dmux->chunks_; c != NULL; c = c->next_) {
const uint8_t* const header = mem_buf + c->data_.offset_;
if (!memcmp(header, fourcc, TAG_SIZE)) ++count;
if (count == chunk_num) break;
}
return c;
}
static int SetChunk(const char fourcc[4], int chunk_num,
WebPChunkIterator* const iter) {
const WebPDemuxer* const dmux = (WebPDemuxer*)iter->private_;
int count;
if (dmux == NULL || fourcc == NULL || chunk_num < 0) return 0;
count = ChunkCount(dmux, fourcc);
if (count == 0) return 0;
if (chunk_num == 0) chunk_num = count;
if (chunk_num <= count) {
const uint8_t* const mem_buf = dmux->mem_.buf_;
const Chunk* const chunk = GetChunk(dmux, fourcc, chunk_num);
iter->chunk.bytes = mem_buf + chunk->data_.offset_ + CHUNK_HEADER_SIZE;
iter->chunk.size = chunk->data_.size_ - CHUNK_HEADER_SIZE;
iter->num_chunks = count;
iter->chunk_num = chunk_num;
return 1;
}
return 0;
}
int WebPDemuxGetChunk(const WebPDemuxer* dmux,
const char fourcc[4], int chunk_num,
WebPChunkIterator* iter) {
if (iter == NULL) return 0;
memset(iter, 0, sizeof(*iter));
iter->private_ = (void*)dmux;
return SetChunk(fourcc, chunk_num, iter);
}
int WebPDemuxNextChunk(WebPChunkIterator* iter) {
if (iter != NULL) {
const char* const fourcc =
(const char*)iter->chunk.bytes - CHUNK_HEADER_SIZE;
return SetChunk(fourcc, iter->chunk_num + 1, iter);
}
return 0;
}
int WebPDemuxPrevChunk(WebPChunkIterator* iter) {
if (iter != NULL && iter->chunk_num > 1) {
const char* const fourcc =
(const char*)iter->chunk.bytes - CHUNK_HEADER_SIZE;
return SetChunk(fourcc, iter->chunk_num - 1, iter);
}
return 0;
}
void WebPDemuxReleaseChunkIterator(WebPChunkIterator* iter) {
(void)iter;
}