diff options
Diffstat (limited to 'thirdparty/libwebp/demux/demux.c')
| -rw-r--r-- | thirdparty/libwebp/demux/demux.c | 966 |
1 files changed, 966 insertions, 0 deletions
diff --git a/thirdparty/libwebp/demux/demux.c b/thirdparty/libwebp/demux/demux.c new file mode 100644 index 0000000000..0d2989f6f4 --- /dev/null +++ b/thirdparty/libwebp/demux/demux.c @@ -0,0 +1,966 @@ +// 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 "../webp/config.h" +#endif + +#include <assert.h> +#include <stdlib.h> +#include <string.h> + +#include "../utils/utils.h" +#include "../webp/decode.h" // WebPGetFeatures +#include "../webp/demux.h" +#include "../webp/format_constants.h" + +#define DMUX_MAJ_VERSION 0 +#define DMUX_MIN_VERSION 3 +#define DMUX_REV_VERSION 0 + +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'. +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) < 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); + 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->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; + 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. + status = StoreFrame(dmux->num_frames_ + 1, anmf_payload_size, mem, frame); + 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, but we need + // at least CHUNK_HEADER_SIZE for parsing. + status = StoreFrame(1, CHUNK_HEADER_SIZE, &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); + 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'): { + // 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 int is_fragmented = !!(dmux->feature_flags_ & FRAGMENTS_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 (is_fragmented) return 0; + + 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; +} + |