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libwebp/demux: add simple format parsing
Adds image parsing / validation framework for 'VP8 '/'VP8L' files Change-Id: I8b0a5d1f20d86ab137c881a01dba3275ea191aa4
This commit is contained in:
James Zern
parent
f8f94081be
commit
962dcef6a8
320
src/mux/demux.c
320
src/mux/demux.c
@ -10,22 +10,330 @@
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#include "../webp/mux.h"
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#include <stdlib.h>
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#include <string.h>
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#include "../webp/decode.h" // WebPGetInfo
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#include "../webp/format_constants.h"
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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#define MKFOURCC(a, b, c, d) ((uint32_t)(a) | (b) << 8 | (c) << 16 | (d) << 24)
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typedef struct {
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size_t start_; // start location of the data
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size_t end_; // end location
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size_t riff_end_; // riff chunk end location, can be > end_.
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size_t buf_size_; // size of the buffer
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const uint8_t* buf_;
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} MemBuffer;
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typedef struct {
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size_t offset_;
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size_t size_;
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} ChunkData;
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typedef struct Frame {
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int width_, height_;
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int frame_num_; // the referent frame number for use in assembling tiles.
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int complete_; // img_components_ contains a full image.
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ChunkData img_components_[2]; // 0=VP8{,L} 1=ALPH
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struct Frame* next_;
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} Frame;
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struct WebPDemuxer {
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MemBuffer mem_;
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WebPDemuxState state_;
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int canvas_width_, canvas_height_;
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int num_frames_;
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Frame* frames_;
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};
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typedef enum {
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PARSE_OK,
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PARSE_NEED_MORE_DATA,
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PARSE_ERROR
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} ParseStatus;
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typedef struct ChunkParser {
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uint8_t id[4];
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ParseStatus (*parse)(WebPDemuxer* const dmux);
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int (*valid)(const WebPDemuxer* const dmux);
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} ChunkParser;
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static int IsValidSimpleFormat(const WebPDemuxer* const dmux);
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static ParseStatus ParseSingleImage(WebPDemuxer* const dmux);
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static const ChunkParser kMasterChunks[] = {
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{ { 'V', 'P', '8', ' ' }, ParseSingleImage, IsValidSimpleFormat },
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{ { 'V', 'P', '8', 'L' }, ParseSingleImage, IsValidSimpleFormat },
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{ { '0', '0', '0', '0' }, NULL, NULL },
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};
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// -----------------------------------------------------------------------------
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// MemBuffer
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static int RemapMemBuffer(MemBuffer* const mem,
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const uint8_t* data, size_t size) {
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if (size < mem->buf_size_) return 0; // can't remap to a shorter buffer!
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mem->buf_ = data;
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mem->end_ = mem->buf_size_ = size;
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return 1;
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}
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static int InitMemBuffer(MemBuffer* const mem,
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const uint8_t* data, size_t size) {
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memset(mem, 0, sizeof(*mem));
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return RemapMemBuffer(mem, data, size);
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}
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// Return the remaining data size available in 'mem'.
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static WEBP_INLINE size_t MemDataSize(const MemBuffer* const mem) {
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return (mem->end_ - mem->start_);
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}
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// Return true if 'size' exceeds the end of the RIFF chunk.
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static WEBP_INLINE int SizeIsInvalid(const MemBuffer* const mem, size_t size) {
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return (size > mem->riff_end_ - mem->start_);
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}
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static WEBP_INLINE void Skip(MemBuffer* const mem, size_t size) {
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mem->start_ += size;
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}
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static WEBP_INLINE void Rewind(MemBuffer* const mem, size_t size) {
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mem->start_ -= size;
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}
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static WEBP_INLINE const uint8_t* GetBuffer(MemBuffer* const mem) {
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return mem->buf_ + mem->start_;
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}
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static WEBP_INLINE uint32_t ReadLE32(const uint8_t* const data) {
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return (uint32_t)(data[0] << 0 | (data[1] << 8) |
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(data[2] << 16) | (data[3] << 24));
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}
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static WEBP_INLINE uint32_t GetLE32(MemBuffer* const mem) {
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const uint8_t* const data = mem->buf_ + mem->start_;
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const uint32_t val = ReadLE32(data);
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Skip(mem, 4);
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return val;
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}
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// -----------------------------------------------------------------------------
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// Secondary chunk parsing
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// Add a frame to the end of the list, ensuring the last frame is complete.
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// Returns true on success, false otherwise.
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static int AddFrame(WebPDemuxer* const dmux, Frame* const frame) {
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const Frame* last_frame = NULL;
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Frame** f = &dmux->frames_;
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while (*f != NULL) {
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last_frame = *f;
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f = &(*f)->next_;
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}
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if (last_frame != NULL && !last_frame->complete_) return 0;
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*f = frame;
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frame->next_ = NULL;
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return 1;
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}
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// Store image bearing chunks to 'frame'.
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static ParseStatus StoreFrame(int frame_num, MemBuffer* const mem,
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Frame* const frame) {
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int image_chunks = 0;
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int done = (MemDataSize(mem) < CHUNK_HEADER_SIZE);
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ParseStatus status = PARSE_OK;
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if (done) return PARSE_NEED_MORE_DATA;
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do {
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const size_t chunk_start_offset = mem->start_;
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const uint32_t fourcc = GetLE32(mem);
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const uint32_t payload_size = GetLE32(mem);
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const uint32_t payload_size_padded = payload_size + (payload_size & 1);
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const size_t payload_available = (payload_size_padded > MemDataSize(mem))
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? MemDataSize(mem) : payload_size_padded;
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const size_t chunk_size = CHUNK_HEADER_SIZE + payload_available;
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if (payload_size > MAX_CHUNK_PAYLOAD) return PARSE_ERROR;
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if (SizeIsInvalid(mem, payload_size_padded)) return PARSE_ERROR;
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if (payload_size_padded > MemDataSize(mem)) status = PARSE_NEED_MORE_DATA;
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switch (fourcc) {
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case MKFOURCC('V', 'P', '8', ' '):
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case MKFOURCC('V', 'P', '8', 'L'):
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if (image_chunks == 0) {
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int width = 0, height = 0;
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++image_chunks;
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frame->img_components_[0].offset_ = chunk_start_offset;
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frame->img_components_[0].size_ = chunk_size;
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// Extract the width and height from the bitstream, tolerating
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// failures when the data is incomplete.
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if (!WebPGetInfo(mem->buf_ + frame->img_components_[0].offset_,
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frame->img_components_[0].size_, &width, &height) &&
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status != PARSE_NEED_MORE_DATA) {
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return PARSE_ERROR;
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}
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frame->width_ = width;
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frame->height_ = height;
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frame->frame_num_ = frame_num;
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frame->complete_ = (status == PARSE_OK);
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Skip(mem, payload_available);
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} else {
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goto Done;
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}
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break;
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Done:
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default:
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// Restore fourcc/size when moving up one level in parsing.
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Rewind(mem, CHUNK_HEADER_SIZE);
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done = 1;
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break;
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}
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if (mem->start_ == mem->riff_end_) {
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done = 1;
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} else if (MemDataSize(mem) < CHUNK_HEADER_SIZE) {
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status = PARSE_NEED_MORE_DATA;
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}
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} while (!done && status == PARSE_OK);
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return status;
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}
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// -----------------------------------------------------------------------------
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// Primary chunk parsing
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static int ReadHeader(MemBuffer* const mem) {
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const size_t min_size = RIFF_HEADER_SIZE + CHUNK_HEADER_SIZE;
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uint32_t riff_size;
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// Basic file level validation.
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if (MemDataSize(mem) < min_size) return 0;
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if (memcmp(GetBuffer(mem), "RIFF", CHUNK_SIZE_BYTES) ||
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memcmp(GetBuffer(mem) + CHUNK_HEADER_SIZE, "WEBP", CHUNK_SIZE_BYTES)) {
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return 0;
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}
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riff_size = ReadLE32(GetBuffer(mem) + TAG_SIZE);
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if (riff_size < CHUNK_HEADER_SIZE) return 0;
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if (riff_size > MAX_CHUNK_PAYLOAD) return 0;
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// There's no point in reading past the end of the RIFF chunk
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mem->riff_end_ = riff_size + CHUNK_HEADER_SIZE;
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if (mem->buf_size_ > mem->riff_end_) {
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mem->buf_size_ = mem->end_ = mem->riff_end_;
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}
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Skip(mem, RIFF_HEADER_SIZE);
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return 1;
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}
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static int IsValidSimpleFormat(const WebPDemuxer* const dmux) {
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const Frame* const frame = dmux->frames_;
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if (dmux->state_ == WEBP_DEMUX_PARSING_HEADER) return 1;
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if (dmux->canvas_width_ <= 0 || dmux->canvas_height_ <= 0) return 0;
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if (dmux->state_ == WEBP_DEMUX_DONE && frame == NULL) return 0;
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if (frame->width_ <= 0 || frame->height_ <= 0) return 0;
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return 1;
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}
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static ParseStatus ParseSingleImage(WebPDemuxer* const dmux) {
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const size_t min_size = CHUNK_HEADER_SIZE;
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MemBuffer* const mem = &dmux->mem_;
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Frame* frame;
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ParseStatus status;
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if (dmux->frames_ != NULL) return PARSE_ERROR;
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if (MemDataSize(mem) < min_size) return PARSE_NEED_MORE_DATA;
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frame = (Frame*)calloc(1, sizeof(*frame));
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if (frame == NULL) return PARSE_ERROR;
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status = StoreFrame(1, &dmux->mem_, frame);
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if (status != PARSE_ERROR) {
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// Use the frame width/height as the canvas values for non-vp8x files.
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if (frame->width_ > 0 && frame->height_ > 0) {
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dmux->state_ = WEBP_DEMUX_PARSED_HEADER;
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dmux->canvas_width_ = frame->width_;
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dmux->canvas_height_ = frame->height_;
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}
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AddFrame(dmux, frame);
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dmux->num_frames_ = 1;
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} else {
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free(frame);
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}
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return status;
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}
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// -----------------------------------------------------------------------------
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// WebPDemuxer object
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static void InitDemux(WebPDemuxer* const dmux, const MemBuffer* const mem) {
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dmux->state_ = WEBP_DEMUX_PARSING_HEADER;
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dmux->canvas_width_ = -1;
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dmux->canvas_height_ = -1;
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dmux->mem_ = *mem;
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}
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WebPDemuxer* WebPDemuxInternal(
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const WebPData* const data, int allow_partial,
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WebPDemuxState* const state, int version) {
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(void)data;
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(void)allow_partial;
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(void)state;
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(void)version;
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return NULL;
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const ChunkParser* parser;
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int partial;
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ParseStatus status = PARSE_ERROR;
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MemBuffer mem;
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WebPDemuxer* dmux;
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if (version != WEBP_DEMUX_ABI_VERSION) return NULL;
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if (data == NULL || data->bytes_ == NULL || data->size_ == 0) return NULL;
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if (!InitMemBuffer(&mem, data->bytes_, data->size_)) return NULL;
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if (!ReadHeader(&mem)) return NULL;
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partial = (mem.buf_size_ < mem.riff_end_);
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if (!allow_partial && partial) return NULL;
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dmux = (WebPDemuxer*)calloc(1, sizeof(*dmux));
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if (dmux == NULL) return NULL;
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InitDemux(dmux, &mem);
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for (parser = kMasterChunks; parser->parse != NULL; ++parser) {
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if (!memcmp(parser->id, GetBuffer(&dmux->mem_), TAG_SIZE)) {
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status = parser->parse(dmux);
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if (status == PARSE_OK) dmux->state_ = WEBP_DEMUX_DONE;
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if (status != PARSE_ERROR && !parser->valid(dmux)) status = PARSE_ERROR;
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break;
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}
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}
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if (state) *state = dmux->state_;
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if (status == PARSE_ERROR) {
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WebPDemuxDelete(dmux);
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return NULL;
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}
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return dmux;
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}
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void WebPDemuxDelete(WebPDemuxer* const dmux) {
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(void)dmux;
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Frame* f;
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if (dmux == NULL) return;
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for (f = dmux->frames_; f != NULL;) {
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Frame* const cur_frame = f;
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f = f->next_;
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free(cur_frame);
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}
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free(dmux);
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}
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#if defined(__cplusplus) || defined(c_plusplus)
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