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1 // Copyright 2010 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // Main decoding functions for WEBP images.
11 //
12 // Author: Skal (pascal.massimino@gmail.com)
13 
14 #include <stdlib.h>
15 
16 #include "src/dec/vp8i_dec.h"
17 #include "src/dec/vp8li_dec.h"
18 #include "src/dec/webpi_dec.h"
19 #include "src/utils/utils.h"
20 #include "src/webp/mux_types.h"  // ALPHA_FLAG
21 
22 //------------------------------------------------------------------------------
23 // RIFF layout is:
24 //   Offset  tag
25 //   0...3   "RIFF" 4-byte tag
26 //   4...7   size of image data (including metadata) starting at offset 8
27 //   8...11  "WEBP"   our form-type signature
28 // The RIFF container (12 bytes) is followed by appropriate chunks:
29 //   12..15  "VP8 ": 4-bytes tags, signaling the use of VP8 video format
30 //   16..19  size of the raw VP8 image data, starting at offset 20
31 //   20....  the VP8 bytes
32 // Or,
33 //   12..15  "VP8L": 4-bytes tags, signaling the use of VP8L lossless format
34 //   16..19  size of the raw VP8L image data, starting at offset 20
35 //   20....  the VP8L bytes
36 // Or,
37 //   12..15  "VP8X": 4-bytes tags, describing the extended-VP8 chunk.
38 //   16..19  size of the VP8X chunk starting at offset 20.
39 //   20..23  VP8X flags bit-map corresponding to the chunk-types present.
40 //   24..26  Width of the Canvas Image.
41 //   27..29  Height of the Canvas Image.
42 // There can be extra chunks after the "VP8X" chunk (ICCP, ANMF, VP8, VP8L,
43 // XMP, EXIF  ...)
44 // All sizes are in little-endian order.
45 // Note: chunk data size must be padded to multiple of 2 when written.
46 
47 // Validates the RIFF container (if detected) and skips over it.
48 // If a RIFF container is detected, returns:
49 //     VP8_STATUS_BITSTREAM_ERROR for invalid header,
50 //     VP8_STATUS_NOT_ENOUGH_DATA for truncated data if have_all_data is true,
51 // and VP8_STATUS_OK otherwise.
52 // In case there are not enough bytes (partial RIFF container), return 0 for
53 // *riff_size. Else return the RIFF size extracted from the header.
ParseRIFF(const uint8_t ** const data,size_t * const data_size,int have_all_data,size_t * const riff_size)54 static VP8StatusCode ParseRIFF(const uint8_t** const data,
55                                size_t* const data_size, int have_all_data,
56                                size_t* const riff_size) {
57   assert(data != NULL);
58   assert(data_size != NULL);
59   assert(riff_size != NULL);
60 
61   *riff_size = 0;  // Default: no RIFF present.
62   if (*data_size >= RIFF_HEADER_SIZE && !memcmp(*data, "RIFF", TAG_SIZE)) {
63     if (memcmp(*data + 8, "WEBP", TAG_SIZE)) {
64       return VP8_STATUS_BITSTREAM_ERROR;  // Wrong image file signature.
65     } else {
66       const uint32_t size = GetLE32(*data + TAG_SIZE);
67       // Check that we have at least one chunk (i.e "WEBP" + "VP8?nnnn").
68       if (size < TAG_SIZE + CHUNK_HEADER_SIZE) {
69         return VP8_STATUS_BITSTREAM_ERROR;
70       }
71       if (size > MAX_CHUNK_PAYLOAD) {
72         return VP8_STATUS_BITSTREAM_ERROR;
73       }
74       if (have_all_data && (size > *data_size - CHUNK_HEADER_SIZE)) {
75         return VP8_STATUS_NOT_ENOUGH_DATA;  // Truncated bitstream.
76       }
77       // We have a RIFF container. Skip it.
78       *riff_size = size;
79       *data += RIFF_HEADER_SIZE;
80       *data_size -= RIFF_HEADER_SIZE;
81     }
82   }
83   return VP8_STATUS_OK;
84 }
85 
86 // Validates the VP8X header and skips over it.
87 // Returns VP8_STATUS_BITSTREAM_ERROR for invalid VP8X header,
88 //         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
89 //         VP8_STATUS_OK otherwise.
90 // If a VP8X chunk is found, found_vp8x is set to true and *width_ptr,
91 // *height_ptr and *flags_ptr are set to the corresponding values extracted
92 // from the VP8X chunk.
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)93 static VP8StatusCode ParseVP8X(const uint8_t** const data,
94                                size_t* const data_size,
95                                int* const found_vp8x,
96                                int* const width_ptr, int* const height_ptr,
97                                uint32_t* const flags_ptr) {
98   const uint32_t vp8x_size = CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
99   assert(data != NULL);
100   assert(data_size != NULL);
101   assert(found_vp8x != NULL);
102 
103   *found_vp8x = 0;
104 
105   if (*data_size < CHUNK_HEADER_SIZE) {
106     return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
107   }
108 
109   if (!memcmp(*data, "VP8X", TAG_SIZE)) {
110     int width, height;
111     uint32_t flags;
112     const uint32_t chunk_size = GetLE32(*data + TAG_SIZE);
113     if (chunk_size != VP8X_CHUNK_SIZE) {
114       return VP8_STATUS_BITSTREAM_ERROR;  // Wrong chunk size.
115     }
116 
117     // Verify if enough data is available to validate the VP8X chunk.
118     if (*data_size < vp8x_size) {
119       return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
120     }
121     flags = GetLE32(*data + 8);
122     width = 1 + GetLE24(*data + 12);
123     height = 1 + GetLE24(*data + 15);
124     if (width * (uint64_t)height >= MAX_IMAGE_AREA) {
125       return VP8_STATUS_BITSTREAM_ERROR;  // image is too large
126     }
127 
128     if (flags_ptr != NULL) *flags_ptr = flags;
129     if (width_ptr != NULL) *width_ptr = width;
130     if (height_ptr != NULL) *height_ptr = height;
131     // Skip over VP8X header bytes.
132     *data += vp8x_size;
133     *data_size -= vp8x_size;
134     *found_vp8x = 1;
135   }
136   return VP8_STATUS_OK;
137 }
138 
139 // Skips to the next VP8/VP8L chunk header in the data given the size of the
140 // RIFF chunk 'riff_size'.
141 // Returns VP8_STATUS_BITSTREAM_ERROR if any invalid chunk size is encountered,
142 //         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
143 //         VP8_STATUS_OK otherwise.
144 // If an alpha chunk is found, *alpha_data and *alpha_size are set
145 // appropriately.
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)146 static VP8StatusCode ParseOptionalChunks(const uint8_t** const data,
147                                          size_t* const data_size,
148                                          size_t const riff_size,
149                                          const uint8_t** const alpha_data,
150                                          size_t* const alpha_size) {
151   const uint8_t* buf;
152   size_t buf_size;
153   uint32_t total_size = TAG_SIZE +           // "WEBP".
154                         CHUNK_HEADER_SIZE +  // "VP8Xnnnn".
155                         VP8X_CHUNK_SIZE;     // data.
156   assert(data != NULL);
157   assert(data_size != NULL);
158   buf = *data;
159   buf_size = *data_size;
160 
161   assert(alpha_data != NULL);
162   assert(alpha_size != NULL);
163   *alpha_data = NULL;
164   *alpha_size = 0;
165 
166   while (1) {
167     uint32_t chunk_size;
168     uint32_t disk_chunk_size;   // chunk_size with padding
169 
170     *data = buf;
171     *data_size = buf_size;
172 
173     if (buf_size < CHUNK_HEADER_SIZE) {  // Insufficient data.
174       return VP8_STATUS_NOT_ENOUGH_DATA;
175     }
176 
177     chunk_size = GetLE32(buf + TAG_SIZE);
178     if (chunk_size > MAX_CHUNK_PAYLOAD) {
179       return VP8_STATUS_BITSTREAM_ERROR;          // Not a valid chunk size.
180     }
181     // For odd-sized chunk-payload, there's one byte padding at the end.
182     disk_chunk_size = (CHUNK_HEADER_SIZE + chunk_size + 1) & ~1u;
183     total_size += disk_chunk_size;
184 
185     // Check that total bytes skipped so far does not exceed riff_size.
186     if (riff_size > 0 && (total_size > riff_size)) {
187       return VP8_STATUS_BITSTREAM_ERROR;          // Not a valid chunk size.
188     }
189 
190     // Start of a (possibly incomplete) VP8/VP8L chunk implies that we have
191     // parsed all the optional chunks.
192     // Note: This check must occur before the check 'buf_size < disk_chunk_size'
193     // below to allow incomplete VP8/VP8L chunks.
194     if (!memcmp(buf, "VP8 ", TAG_SIZE) ||
195         !memcmp(buf, "VP8L", TAG_SIZE)) {
196       return VP8_STATUS_OK;
197     }
198 
199     if (buf_size < disk_chunk_size) {             // Insufficient data.
200       return VP8_STATUS_NOT_ENOUGH_DATA;
201     }
202 
203     if (!memcmp(buf, "ALPH", TAG_SIZE)) {         // A valid ALPH header.
204       *alpha_data = buf + CHUNK_HEADER_SIZE;
205       *alpha_size = chunk_size;
206     }
207 
208     // We have a full and valid chunk; skip it.
209     buf += disk_chunk_size;
210     buf_size -= disk_chunk_size;
211   }
212 }
213 
214 // Validates the VP8/VP8L Header ("VP8 nnnn" or "VP8L nnnn") and skips over it.
215 // Returns VP8_STATUS_BITSTREAM_ERROR for invalid (chunk larger than
216 //         riff_size) VP8/VP8L header,
217 //         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
218 //         VP8_STATUS_OK otherwise.
219 // If a VP8/VP8L chunk is found, *chunk_size is set to the total number of bytes
220 // extracted from the VP8/VP8L chunk header.
221 // The flag '*is_lossless' is set to 1 in case of VP8L chunk / raw VP8L data.
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)222 static VP8StatusCode ParseVP8Header(const uint8_t** const data_ptr,
223                                     size_t* const data_size, int have_all_data,
224                                     size_t riff_size, size_t* const chunk_size,
225                                     int* const is_lossless) {
226   const uint8_t* const data = *data_ptr;
227   const int is_vp8 = !memcmp(data, "VP8 ", TAG_SIZE);
228   const int is_vp8l = !memcmp(data, "VP8L", TAG_SIZE);
229   const uint32_t minimal_size =
230       TAG_SIZE + CHUNK_HEADER_SIZE;  // "WEBP" + "VP8 nnnn" OR
231                                      // "WEBP" + "VP8Lnnnn"
232   assert(data != NULL);
233   assert(data_size != NULL);
234   assert(chunk_size != NULL);
235   assert(is_lossless != NULL);
236 
237   if (*data_size < CHUNK_HEADER_SIZE) {
238     return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
239   }
240 
241   if (is_vp8 || is_vp8l) {
242     // Bitstream contains VP8/VP8L header.
243     const uint32_t size = GetLE32(data + TAG_SIZE);
244     if ((riff_size >= minimal_size) && (size > riff_size - minimal_size)) {
245       return VP8_STATUS_BITSTREAM_ERROR;  // Inconsistent size information.
246     }
247     if (have_all_data && (size > *data_size - CHUNK_HEADER_SIZE)) {
248       return VP8_STATUS_NOT_ENOUGH_DATA;  // Truncated bitstream.
249     }
250     // Skip over CHUNK_HEADER_SIZE bytes from VP8/VP8L Header.
251     *chunk_size = size;
252     *data_ptr += CHUNK_HEADER_SIZE;
253     *data_size -= CHUNK_HEADER_SIZE;
254     *is_lossless = is_vp8l;
255   } else {
256     // Raw VP8/VP8L bitstream (no header).
257     *is_lossless = VP8LCheckSignature(data, *data_size);
258     *chunk_size = *data_size;
259   }
260 
261   return VP8_STATUS_OK;
262 }
263 
264 //------------------------------------------------------------------------------
265 
266 // Fetch '*width', '*height', '*has_alpha' and fill out 'headers' based on
267 // 'data'. All the output parameters may be NULL. If 'headers' is NULL only the
268 // minimal amount will be read to fetch the remaining parameters.
269 // If 'headers' is non-NULL this function will attempt to locate both alpha
270 // data (with or without a VP8X chunk) and the bitstream chunk (VP8/VP8L).
271 // Note: The following chunk sequences (before the raw VP8/VP8L data) are
272 // considered valid by this function:
273 // RIFF + VP8(L)
274 // RIFF + VP8X + (optional chunks) + VP8(L)
275 // ALPH + VP8 <-- Not a valid WebP format: only allowed for internal purpose.
276 // VP8(L)     <-- Not a valid WebP format: only allowed for internal purpose.
ParseHeadersInternal(const uint8_t * data,size_t data_size,int * const width,int * const height,int * const has_alpha,int * const has_animation,int * const format,WebPHeaderStructure * const headers)277 static VP8StatusCode ParseHeadersInternal(const uint8_t* data,
278                                           size_t data_size,
279                                           int* const width,
280                                           int* const height,
281                                           int* const has_alpha,
282                                           int* const has_animation,
283                                           int* const format,
284                                           WebPHeaderStructure* const headers) {
285   int canvas_width = 0;
286   int canvas_height = 0;
287   int image_width = 0;
288   int image_height = 0;
289   int found_riff = 0;
290   int found_vp8x = 0;
291   int animation_present = 0;
292   const int have_all_data = (headers != NULL) ? headers->have_all_data : 0;
293 
294   VP8StatusCode status;
295   WebPHeaderStructure hdrs;
296 
297   if (data == NULL || data_size < RIFF_HEADER_SIZE) {
298     return VP8_STATUS_NOT_ENOUGH_DATA;
299   }
300   memset(&hdrs, 0, sizeof(hdrs));
301   hdrs.data = data;
302   hdrs.data_size = data_size;
303 
304   // Skip over RIFF header.
305   status = ParseRIFF(&data, &data_size, have_all_data, &hdrs.riff_size);
306   if (status != VP8_STATUS_OK) {
307     return status;   // Wrong RIFF header / insufficient data.
308   }
309   found_riff = (hdrs.riff_size > 0);
310 
311   // Skip over VP8X.
312   {
313     uint32_t flags = 0;
314     status = ParseVP8X(&data, &data_size, &found_vp8x,
315                        &canvas_width, &canvas_height, &flags);
316     if (status != VP8_STATUS_OK) {
317       return status;  // Wrong VP8X / insufficient data.
318     }
319     animation_present = !!(flags & ANIMATION_FLAG);
320     if (!found_riff && found_vp8x) {
321       // Note: This restriction may be removed in the future, if it becomes
322       // necessary to send VP8X chunk to the decoder.
323       return VP8_STATUS_BITSTREAM_ERROR;
324     }
325     if (has_alpha != NULL) *has_alpha = !!(flags & ALPHA_FLAG);
326     if (has_animation != NULL) *has_animation = animation_present;
327     if (format != NULL) *format = 0;   // default = undefined
328 
329     image_width = canvas_width;
330     image_height = canvas_height;
331     if (found_vp8x && animation_present && headers == NULL) {
332       status = VP8_STATUS_OK;
333       goto ReturnWidthHeight;  // Just return features from VP8X header.
334     }
335   }
336 
337   if (data_size < TAG_SIZE) {
338     status = VP8_STATUS_NOT_ENOUGH_DATA;
339     goto ReturnWidthHeight;
340   }
341 
342   // Skip over optional chunks if data started with "RIFF + VP8X" or "ALPH".
343   if ((found_riff && found_vp8x) ||
344       (!found_riff && !found_vp8x && !memcmp(data, "ALPH", TAG_SIZE))) {
345     status = ParseOptionalChunks(&data, &data_size, hdrs.riff_size,
346                                  &hdrs.alpha_data, &hdrs.alpha_data_size);
347     if (status != VP8_STATUS_OK) {
348       goto ReturnWidthHeight;  // Invalid chunk size / insufficient data.
349     }
350   }
351 
352   // Skip over VP8/VP8L header.
353   status = ParseVP8Header(&data, &data_size, have_all_data, hdrs.riff_size,
354                           &hdrs.compressed_size, &hdrs.is_lossless);
355   if (status != VP8_STATUS_OK) {
356     goto ReturnWidthHeight;  // Wrong VP8/VP8L chunk-header / insufficient data.
357   }
358   if (hdrs.compressed_size > MAX_CHUNK_PAYLOAD) {
359     return VP8_STATUS_BITSTREAM_ERROR;
360   }
361 
362   if (format != NULL && !animation_present) {
363     *format = hdrs.is_lossless ? 2 : 1;
364   }
365 
366   if (!hdrs.is_lossless) {
367     if (data_size < VP8_FRAME_HEADER_SIZE) {
368       status = VP8_STATUS_NOT_ENOUGH_DATA;
369       goto ReturnWidthHeight;
370     }
371     // Validates raw VP8 data.
372     if (!VP8GetInfo(data, data_size, (uint32_t)hdrs.compressed_size,
373                     &image_width, &image_height)) {
374       return VP8_STATUS_BITSTREAM_ERROR;
375     }
376   } else {
377     if (data_size < VP8L_FRAME_HEADER_SIZE) {
378       status = VP8_STATUS_NOT_ENOUGH_DATA;
379       goto ReturnWidthHeight;
380     }
381     // Validates raw VP8L data.
382     if (!VP8LGetInfo(data, data_size, &image_width, &image_height, has_alpha)) {
383       return VP8_STATUS_BITSTREAM_ERROR;
384     }
385   }
386   // Validates image size coherency.
387   if (found_vp8x) {
388     if (canvas_width != image_width || canvas_height != image_height) {
389       return VP8_STATUS_BITSTREAM_ERROR;
390     }
391   }
392   if (headers != NULL) {
393     *headers = hdrs;
394     headers->offset = data - headers->data;
395     assert((uint64_t)(data - headers->data) < MAX_CHUNK_PAYLOAD);
396     assert(headers->offset == headers->data_size - data_size);
397   }
398  ReturnWidthHeight:
399   if (status == VP8_STATUS_OK ||
400       (status == VP8_STATUS_NOT_ENOUGH_DATA && found_vp8x && headers == NULL)) {
401     if (has_alpha != NULL) {
402       // If the data did not contain a VP8X/VP8L chunk the only definitive way
403       // to set this is by looking for alpha data (from an ALPH chunk).
404       *has_alpha |= (hdrs.alpha_data != NULL);
405     }
406     if (width != NULL) *width = image_width;
407     if (height != NULL) *height = image_height;
408     return VP8_STATUS_OK;
409   } else {
410     return status;
411   }
412 }
413 
WebPParseHeaders(WebPHeaderStructure * const headers)414 VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers) {
415   // status is marked volatile as a workaround for a clang-3.8 (aarch64) bug
416   volatile VP8StatusCode status;
417   int has_animation = 0;
418   assert(headers != NULL);
419   // fill out headers, ignore width/height/has_alpha.
420   status = ParseHeadersInternal(headers->data, headers->data_size,
421                                 NULL, NULL, NULL, &has_animation,
422                                 NULL, headers);
423   if (status == VP8_STATUS_OK || status == VP8_STATUS_NOT_ENOUGH_DATA) {
424     // The WebPDemux API + libwebp can be used to decode individual
425     // uncomposited frames or the WebPAnimDecoder can be used to fully
426     // reconstruct them (see webp/demux.h).
427     if (has_animation) {
428       status = VP8_STATUS_UNSUPPORTED_FEATURE;
429     }
430   }
431   return status;
432 }
433 
434 //------------------------------------------------------------------------------
435 // WebPDecParams
436 
WebPResetDecParams(WebPDecParams * const params)437 void WebPResetDecParams(WebPDecParams* const params) {
438   if (params != NULL) {
439     memset(params, 0, sizeof(*params));
440   }
441 }
442 
443 //------------------------------------------------------------------------------
444 // "Into" decoding variants
445 
446 // Main flow
DecodeInto(const uint8_t * const data,size_t data_size,WebPDecParams * const params)447 static VP8StatusCode DecodeInto(const uint8_t* const data, size_t data_size,
448                                 WebPDecParams* const params) {
449   VP8StatusCode status;
450   VP8Io io;
451   WebPHeaderStructure headers;
452 
453   headers.data = data;
454   headers.data_size = data_size;
455   headers.have_all_data = 1;
456   status = WebPParseHeaders(&headers);   // Process Pre-VP8 chunks.
457   if (status != VP8_STATUS_OK) {
458     return status;
459   }
460 
461   assert(params != NULL);
462   VP8InitIo(&io);
463   io.data = headers.data + headers.offset;
464   io.data_size = headers.data_size - headers.offset;
465   WebPInitCustomIo(params, &io);  // Plug the I/O functions.
466 
467   if (!headers.is_lossless) {
468     VP8Decoder* const dec = VP8New();
469     if (dec == NULL) {
470       return VP8_STATUS_OUT_OF_MEMORY;
471     }
472     dec->alpha_data_ = headers.alpha_data;
473     dec->alpha_data_size_ = headers.alpha_data_size;
474 
475     // Decode bitstream header, update io->width/io->height.
476     if (!VP8GetHeaders(dec, &io)) {
477       status = dec->status_;   // An error occurred. Grab error status.
478     } else {
479       // Allocate/check output buffers.
480       status = WebPAllocateDecBuffer(io.width, io.height, params->options,
481                                      params->output);
482       if (status == VP8_STATUS_OK) {  // Decode
483         // This change must be done before calling VP8Decode()
484         dec->mt_method_ = VP8GetThreadMethod(params->options, &headers,
485                                              io.width, io.height);
486         VP8InitDithering(params->options, dec);
487         if (!VP8Decode(dec, &io)) {
488           status = dec->status_;
489         }
490       }
491     }
492     VP8Delete(dec);
493   } else {
494     VP8LDecoder* const dec = VP8LNew();
495     if (dec == NULL) {
496       return VP8_STATUS_OUT_OF_MEMORY;
497     }
498     if (!VP8LDecodeHeader(dec, &io)) {
499       status = dec->status_;   // An error occurred. Grab error status.
500     } else {
501       // Allocate/check output buffers.
502       status = WebPAllocateDecBuffer(io.width, io.height, params->options,
503                                      params->output);
504       if (status == VP8_STATUS_OK) {  // Decode
505         if (!VP8LDecodeImage(dec)) {
506           status = dec->status_;
507         }
508       }
509     }
510     VP8LDelete(dec);
511   }
512 
513   if (status != VP8_STATUS_OK) {
514     WebPFreeDecBuffer(params->output);
515   } else {
516     if (params->options != NULL && params->options->flip) {
517       // This restores the original stride values if options->flip was used
518       // during the call to WebPAllocateDecBuffer above.
519       status = WebPFlipBuffer(params->output);
520     }
521   }
522   return status;
523 }
524 
525 // Helpers
DecodeIntoRGBABuffer(WEBP_CSP_MODE colorspace,const uint8_t * const data,size_t data_size,uint8_t * const rgba,int stride,size_t size)526 static uint8_t* DecodeIntoRGBABuffer(WEBP_CSP_MODE colorspace,
527                                      const uint8_t* const data,
528                                      size_t data_size,
529                                      uint8_t* const rgba,
530                                      int stride, size_t size) {
531   WebPDecParams params;
532   WebPDecBuffer buf;
533   if (rgba == NULL) {
534     return NULL;
535   }
536   WebPInitDecBuffer(&buf);
537   WebPResetDecParams(&params);
538   params.output = &buf;
539   buf.colorspace    = colorspace;
540   buf.u.RGBA.rgba   = rgba;
541   buf.u.RGBA.stride = stride;
542   buf.u.RGBA.size   = size;
543   buf.is_external_memory = 1;
544   if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
545     return NULL;
546   }
547   return rgba;
548 }
549 
WebPDecodeRGBInto(const uint8_t * data,size_t data_size,uint8_t * output,size_t size,int stride)550 uint8_t* WebPDecodeRGBInto(const uint8_t* data, size_t data_size,
551                            uint8_t* output, size_t size, int stride) {
552   return DecodeIntoRGBABuffer(MODE_RGB, data, data_size, output, stride, size);
553 }
554 
WebPDecodeRGBAInto(const uint8_t * data,size_t data_size,uint8_t * output,size_t size,int stride)555 uint8_t* WebPDecodeRGBAInto(const uint8_t* data, size_t data_size,
556                             uint8_t* output, size_t size, int stride) {
557   return DecodeIntoRGBABuffer(MODE_RGBA, data, data_size, output, stride, size);
558 }
559 
WebPDecodeARGBInto(const uint8_t * data,size_t data_size,uint8_t * output,size_t size,int stride)560 uint8_t* WebPDecodeARGBInto(const uint8_t* data, size_t data_size,
561                             uint8_t* output, size_t size, int stride) {
562   return DecodeIntoRGBABuffer(MODE_ARGB, data, data_size, output, stride, size);
563 }
564 
WebPDecodeBGRInto(const uint8_t * data,size_t data_size,uint8_t * output,size_t size,int stride)565 uint8_t* WebPDecodeBGRInto(const uint8_t* data, size_t data_size,
566                            uint8_t* output, size_t size, int stride) {
567   return DecodeIntoRGBABuffer(MODE_BGR, data, data_size, output, stride, size);
568 }
569 
WebPDecodeBGRAInto(const uint8_t * data,size_t data_size,uint8_t * output,size_t size,int stride)570 uint8_t* WebPDecodeBGRAInto(const uint8_t* data, size_t data_size,
571                             uint8_t* output, size_t size, int stride) {
572   return DecodeIntoRGBABuffer(MODE_BGRA, data, data_size, output, stride, size);
573 }
574 
WebPDecodeYUVInto(const uint8_t * data,size_t data_size,uint8_t * luma,size_t luma_size,int luma_stride,uint8_t * u,size_t u_size,int u_stride,uint8_t * v,size_t v_size,int v_stride)575 uint8_t* WebPDecodeYUVInto(const uint8_t* data, size_t data_size,
576                            uint8_t* luma, size_t luma_size, int luma_stride,
577                            uint8_t* u, size_t u_size, int u_stride,
578                            uint8_t* v, size_t v_size, int v_stride) {
579   WebPDecParams params;
580   WebPDecBuffer output;
581   if (luma == NULL) return NULL;
582   WebPInitDecBuffer(&output);
583   WebPResetDecParams(&params);
584   params.output = &output;
585   output.colorspace      = MODE_YUV;
586   output.u.YUVA.y        = luma;
587   output.u.YUVA.y_stride = luma_stride;
588   output.u.YUVA.y_size   = luma_size;
589   output.u.YUVA.u        = u;
590   output.u.YUVA.u_stride = u_stride;
591   output.u.YUVA.u_size   = u_size;
592   output.u.YUVA.v        = v;
593   output.u.YUVA.v_stride = v_stride;
594   output.u.YUVA.v_size   = v_size;
595   output.is_external_memory = 1;
596   if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
597     return NULL;
598   }
599   return luma;
600 }
601 
602 //------------------------------------------------------------------------------
603 
Decode(WEBP_CSP_MODE mode,const uint8_t * const data,size_t data_size,int * const width,int * const height,WebPDecBuffer * const keep_info)604 static uint8_t* Decode(WEBP_CSP_MODE mode, const uint8_t* const data,
605                        size_t data_size, int* const width, int* const height,
606                        WebPDecBuffer* const keep_info) {
607   WebPDecParams params;
608   WebPDecBuffer output;
609 
610   WebPInitDecBuffer(&output);
611   WebPResetDecParams(&params);
612   params.output = &output;
613   output.colorspace = mode;
614 
615   // Retrieve (and report back) the required dimensions from bitstream.
616   if (!WebPGetInfo(data, data_size, &output.width, &output.height)) {
617     return NULL;
618   }
619   if (width != NULL) *width = output.width;
620   if (height != NULL) *height = output.height;
621 
622   // Decode
623   if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
624     return NULL;
625   }
626   if (keep_info != NULL) {    // keep track of the side-info
627     WebPCopyDecBuffer(&output, keep_info);
628   }
629   // return decoded samples (don't clear 'output'!)
630   return WebPIsRGBMode(mode) ? output.u.RGBA.rgba : output.u.YUVA.y;
631 }
632 
WebPDecodeRGB(const uint8_t * data,size_t data_size,int * width,int * height)633 uint8_t* WebPDecodeRGB(const uint8_t* data, size_t data_size,
634                        int* width, int* height) {
635   return Decode(MODE_RGB, data, data_size, width, height, NULL);
636 }
637 
WebPDecodeRGBA(const uint8_t * data,size_t data_size,int * width,int * height)638 uint8_t* WebPDecodeRGBA(const uint8_t* data, size_t data_size,
639                         int* width, int* height) {
640   return Decode(MODE_RGBA, data, data_size, width, height, NULL);
641 }
642 
WebPDecodeARGB(const uint8_t * data,size_t data_size,int * width,int * height)643 uint8_t* WebPDecodeARGB(const uint8_t* data, size_t data_size,
644                         int* width, int* height) {
645   return Decode(MODE_ARGB, data, data_size, width, height, NULL);
646 }
647 
WebPDecodeBGR(const uint8_t * data,size_t data_size,int * width,int * height)648 uint8_t* WebPDecodeBGR(const uint8_t* data, size_t data_size,
649                        int* width, int* height) {
650   return Decode(MODE_BGR, data, data_size, width, height, NULL);
651 }
652 
WebPDecodeBGRA(const uint8_t * data,size_t data_size,int * width,int * height)653 uint8_t* WebPDecodeBGRA(const uint8_t* data, size_t data_size,
654                         int* width, int* height) {
655   return Decode(MODE_BGRA, data, data_size, width, height, NULL);
656 }
657 
WebPDecodeYUV(const uint8_t * data,size_t data_size,int * width,int * height,uint8_t ** u,uint8_t ** v,int * stride,int * uv_stride)658 uint8_t* WebPDecodeYUV(const uint8_t* data, size_t data_size,
659                        int* width, int* height, uint8_t** u, uint8_t** v,
660                        int* stride, int* uv_stride) {
661   WebPDecBuffer output;   // only to preserve the side-infos
662   uint8_t* const out = Decode(MODE_YUV, data, data_size,
663                               width, height, &output);
664 
665   if (out != NULL) {
666     const WebPYUVABuffer* const buf = &output.u.YUVA;
667     *u = buf->u;
668     *v = buf->v;
669     *stride = buf->y_stride;
670     *uv_stride = buf->u_stride;
671     assert(buf->u_stride == buf->v_stride);
672   }
673   return out;
674 }
675 
DefaultFeatures(WebPBitstreamFeatures * const features)676 static void DefaultFeatures(WebPBitstreamFeatures* const features) {
677   assert(features != NULL);
678   memset(features, 0, sizeof(*features));
679 }
680 
GetFeatures(const uint8_t * const data,size_t data_size,WebPBitstreamFeatures * const features)681 static VP8StatusCode GetFeatures(const uint8_t* const data, size_t data_size,
682                                  WebPBitstreamFeatures* const features) {
683   if (features == NULL || data == NULL) {
684     return VP8_STATUS_INVALID_PARAM;
685   }
686   DefaultFeatures(features);
687 
688   // Only parse enough of the data to retrieve the features.
689   return ParseHeadersInternal(data, data_size,
690                               &features->width, &features->height,
691                               &features->has_alpha, &features->has_animation,
692                               &features->format, NULL);
693 }
694 
695 //------------------------------------------------------------------------------
696 // WebPGetInfo()
697 
WebPGetInfo(const uint8_t * data,size_t data_size,int * width,int * height)698 int WebPGetInfo(const uint8_t* data, size_t data_size,
699                 int* width, int* height) {
700   WebPBitstreamFeatures features;
701 
702   if (GetFeatures(data, data_size, &features) != VP8_STATUS_OK) {
703     return 0;
704   }
705 
706   if (width != NULL) {
707     *width  = features.width;
708   }
709   if (height != NULL) {
710     *height = features.height;
711   }
712 
713   return 1;
714 }
715 
716 //------------------------------------------------------------------------------
717 // Advance decoding API
718 
WebPInitDecoderConfigInternal(WebPDecoderConfig * config,int version)719 int WebPInitDecoderConfigInternal(WebPDecoderConfig* config,
720                                   int version) {
721   if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
722     return 0;   // version mismatch
723   }
724   if (config == NULL) {
725     return 0;
726   }
727   memset(config, 0, sizeof(*config));
728   DefaultFeatures(&config->input);
729   WebPInitDecBuffer(&config->output);
730   return 1;
731 }
732 
WebPGetFeaturesInternal(const uint8_t * data,size_t data_size,WebPBitstreamFeatures * features,int version)733 VP8StatusCode WebPGetFeaturesInternal(const uint8_t* data, size_t data_size,
734                                       WebPBitstreamFeatures* features,
735                                       int version) {
736   if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
737     return VP8_STATUS_INVALID_PARAM;   // version mismatch
738   }
739   if (features == NULL) {
740     return VP8_STATUS_INVALID_PARAM;
741   }
742   return GetFeatures(data, data_size, features);
743 }
744 
WebPDecode(const uint8_t * data,size_t data_size,WebPDecoderConfig * config)745 VP8StatusCode WebPDecode(const uint8_t* data, size_t data_size,
746                          WebPDecoderConfig* config) {
747   WebPDecParams params;
748   VP8StatusCode status;
749 
750   if (config == NULL) {
751     return VP8_STATUS_INVALID_PARAM;
752   }
753 
754   status = GetFeatures(data, data_size, &config->input);
755   if (status != VP8_STATUS_OK) {
756     if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
757       return VP8_STATUS_BITSTREAM_ERROR;  // Not-enough-data treated as error.
758     }
759     return status;
760   }
761 
762   WebPResetDecParams(&params);
763   params.options = &config->options;
764   params.output = &config->output;
765   if (WebPAvoidSlowMemory(params.output, &config->input)) {
766     // decoding to slow memory: use a temporary in-mem buffer to decode into.
767     WebPDecBuffer in_mem_buffer;
768     WebPInitDecBuffer(&in_mem_buffer);
769     in_mem_buffer.colorspace = config->output.colorspace;
770     in_mem_buffer.width = config->input.width;
771     in_mem_buffer.height = config->input.height;
772     params.output = &in_mem_buffer;
773     status = DecodeInto(data, data_size, &params);
774     if (status == VP8_STATUS_OK) {  // do the slow-copy
775       status = WebPCopyDecBufferPixels(&in_mem_buffer, &config->output);
776     }
777     WebPFreeDecBuffer(&in_mem_buffer);
778   } else {
779     status = DecodeInto(data, data_size, &params);
780   }
781 
782   return status;
783 }
784 
785 //------------------------------------------------------------------------------
786 // Cropping and rescaling.
787 
WebPCheckCropDimensions(int image_width,int image_height,int x,int y,int w,int h)788 int WebPCheckCropDimensions(int image_width, int image_height,
789                             int x, int y, int w, int h) {
790   return !(x < 0 || y < 0 || w <= 0 || h <= 0 ||
791            x >= image_width || w > image_width || w > image_width - x ||
792            y >= image_height || h > image_height || h > image_height - y);
793 }
794 
WebPIoInitFromOptions(const WebPDecoderOptions * const options,VP8Io * const io,WEBP_CSP_MODE src_colorspace)795 int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
796                           VP8Io* const io, WEBP_CSP_MODE src_colorspace) {
797   const int W = io->width;
798   const int H = io->height;
799   int x = 0, y = 0, w = W, h = H;
800 
801   // Cropping
802   io->use_cropping = (options != NULL) && options->use_cropping;
803   if (io->use_cropping) {
804     w = options->crop_width;
805     h = options->crop_height;
806     x = options->crop_left;
807     y = options->crop_top;
808     if (!WebPIsRGBMode(src_colorspace)) {   // only snap for YUV420
809       x &= ~1;
810       y &= ~1;
811     }
812     if (!WebPCheckCropDimensions(W, H, x, y, w, h)) {
813       return 0;  // out of frame boundary error
814     }
815   }
816   io->crop_left   = x;
817   io->crop_top    = y;
818   io->crop_right  = x + w;
819   io->crop_bottom = y + h;
820   io->mb_w = w;
821   io->mb_h = h;
822 
823   // Scaling
824   io->use_scaling = (options != NULL) && options->use_scaling;
825   if (io->use_scaling) {
826     int scaled_width = options->scaled_width;
827     int scaled_height = options->scaled_height;
828     if (!WebPRescalerGetScaledDimensions(w, h, &scaled_width, &scaled_height)) {
829       return 0;
830     }
831     io->scaled_width = scaled_width;
832     io->scaled_height = scaled_height;
833   }
834 
835   // Filter
836   io->bypass_filtering = (options != NULL) && options->bypass_filtering;
837 
838   // Fancy upsampler
839 #ifdef FANCY_UPSAMPLING
840   io->fancy_upsampling = (options == NULL) || (!options->no_fancy_upsampling);
841 #endif
842 
843   if (io->use_scaling) {
844     // disable filter (only for large downscaling ratio).
845     io->bypass_filtering |= (io->scaled_width < W * 3 / 4) &&
846                             (io->scaled_height < H * 3 / 4);
847     io->fancy_upsampling = 0;
848   }
849   return 1;
850 }
851 
852 //------------------------------------------------------------------------------
853