1 // Copyright 2011 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 // Internal objects and utils for mux.
11 //
12 // Authors: Urvang (urvang@google.com)
13 // Vikas (vikasa@google.com)
14
15 #include <assert.h>
16 #include "src/mux/muxi.h"
17 #include "src/utils/utils.h"
18
19 #define UNDEFINED_CHUNK_SIZE ((uint32_t)(-1))
20
21 const ChunkInfo kChunks[] = {
22 { MKFOURCC('V', 'P', '8', 'X'), WEBP_CHUNK_VP8X, VP8X_CHUNK_SIZE },
23 { MKFOURCC('I', 'C', 'C', 'P'), WEBP_CHUNK_ICCP, UNDEFINED_CHUNK_SIZE },
24 { MKFOURCC('A', 'N', 'I', 'M'), WEBP_CHUNK_ANIM, ANIM_CHUNK_SIZE },
25 { MKFOURCC('A', 'N', 'M', 'F'), WEBP_CHUNK_ANMF, ANMF_CHUNK_SIZE },
26 { MKFOURCC('A', 'L', 'P', 'H'), WEBP_CHUNK_ALPHA, UNDEFINED_CHUNK_SIZE },
27 { MKFOURCC('V', 'P', '8', ' '), WEBP_CHUNK_IMAGE, UNDEFINED_CHUNK_SIZE },
28 { MKFOURCC('V', 'P', '8', 'L'), WEBP_CHUNK_IMAGE, UNDEFINED_CHUNK_SIZE },
29 { MKFOURCC('E', 'X', 'I', 'F'), WEBP_CHUNK_EXIF, UNDEFINED_CHUNK_SIZE },
30 { MKFOURCC('X', 'M', 'P', ' '), WEBP_CHUNK_XMP, UNDEFINED_CHUNK_SIZE },
31 { NIL_TAG, WEBP_CHUNK_UNKNOWN, UNDEFINED_CHUNK_SIZE },
32
33 { NIL_TAG, WEBP_CHUNK_NIL, UNDEFINED_CHUNK_SIZE }
34 };
35
36 //------------------------------------------------------------------------------
37
WebPGetMuxVersion(void)38 int WebPGetMuxVersion(void) {
39 return (MUX_MAJ_VERSION << 16) | (MUX_MIN_VERSION << 8) | MUX_REV_VERSION;
40 }
41
42 //------------------------------------------------------------------------------
43 // Life of a chunk object.
44
ChunkInit(WebPChunk * const chunk)45 void ChunkInit(WebPChunk* const chunk) {
46 assert(chunk);
47 memset(chunk, 0, sizeof(*chunk));
48 chunk->tag_ = NIL_TAG;
49 }
50
ChunkRelease(WebPChunk * const chunk)51 WebPChunk* ChunkRelease(WebPChunk* const chunk) {
52 WebPChunk* next;
53 if (chunk == NULL) return NULL;
54 if (chunk->owner_) {
55 WebPDataClear(&chunk->data_);
56 }
57 next = chunk->next_;
58 ChunkInit(chunk);
59 return next;
60 }
61
62 //------------------------------------------------------------------------------
63 // Chunk misc methods.
64
ChunkGetIndexFromTag(uint32_t tag)65 CHUNK_INDEX ChunkGetIndexFromTag(uint32_t tag) {
66 int i;
67 for (i = 0; kChunks[i].tag != NIL_TAG; ++i) {
68 if (tag == kChunks[i].tag) return (CHUNK_INDEX)i;
69 }
70 return IDX_UNKNOWN;
71 }
72
ChunkGetIdFromTag(uint32_t tag)73 WebPChunkId ChunkGetIdFromTag(uint32_t tag) {
74 int i;
75 for (i = 0; kChunks[i].tag != NIL_TAG; ++i) {
76 if (tag == kChunks[i].tag) return kChunks[i].id;
77 }
78 return WEBP_CHUNK_UNKNOWN;
79 }
80
ChunkGetTagFromFourCC(const char fourcc[4])81 uint32_t ChunkGetTagFromFourCC(const char fourcc[4]) {
82 return MKFOURCC(fourcc[0], fourcc[1], fourcc[2], fourcc[3]);
83 }
84
ChunkGetIndexFromFourCC(const char fourcc[4])85 CHUNK_INDEX ChunkGetIndexFromFourCC(const char fourcc[4]) {
86 const uint32_t tag = ChunkGetTagFromFourCC(fourcc);
87 return ChunkGetIndexFromTag(tag);
88 }
89
90 //------------------------------------------------------------------------------
91 // Chunk search methods.
92
93 // Returns next chunk in the chunk list with the given tag.
ChunkSearchNextInList(WebPChunk * chunk,uint32_t tag)94 static WebPChunk* ChunkSearchNextInList(WebPChunk* chunk, uint32_t tag) {
95 while (chunk != NULL && chunk->tag_ != tag) {
96 chunk = chunk->next_;
97 }
98 return chunk;
99 }
100
ChunkSearchList(WebPChunk * first,uint32_t nth,uint32_t tag)101 WebPChunk* ChunkSearchList(WebPChunk* first, uint32_t nth, uint32_t tag) {
102 uint32_t iter = nth;
103 first = ChunkSearchNextInList(first, tag);
104 if (first == NULL) return NULL;
105
106 while (--iter != 0) {
107 WebPChunk* next_chunk = ChunkSearchNextInList(first->next_, tag);
108 if (next_chunk == NULL) break;
109 first = next_chunk;
110 }
111 return ((nth > 0) && (iter > 0)) ? NULL : first;
112 }
113
114 // Outputs a pointer to 'prev_chunk->next_',
115 // where 'prev_chunk' is the pointer to the chunk at position (nth - 1).
116 // Returns true if nth chunk was found.
ChunkSearchListToSet(WebPChunk ** chunk_list,uint32_t nth,WebPChunk *** const location)117 static int ChunkSearchListToSet(WebPChunk** chunk_list, uint32_t nth,
118 WebPChunk*** const location) {
119 uint32_t count = 0;
120 assert(chunk_list != NULL);
121 *location = chunk_list;
122
123 while (*chunk_list != NULL) {
124 WebPChunk* const cur_chunk = *chunk_list;
125 ++count;
126 if (count == nth) return 1; // Found.
127 chunk_list = &cur_chunk->next_;
128 *location = chunk_list;
129 }
130
131 // *chunk_list is ok to be NULL if adding at last location.
132 return (nth == 0 || (count == nth - 1)) ? 1 : 0;
133 }
134
135 //------------------------------------------------------------------------------
136 // Chunk writer methods.
137
ChunkAssignData(WebPChunk * chunk,const WebPData * const data,int copy_data,uint32_t tag)138 WebPMuxError ChunkAssignData(WebPChunk* chunk, const WebPData* const data,
139 int copy_data, uint32_t tag) {
140 // For internally allocated chunks, always copy data & make it owner of data.
141 if (tag == kChunks[IDX_VP8X].tag || tag == kChunks[IDX_ANIM].tag) {
142 copy_data = 1;
143 }
144
145 ChunkRelease(chunk);
146
147 if (data != NULL) {
148 if (copy_data) { // Copy data.
149 if (!WebPDataCopy(data, &chunk->data_)) return WEBP_MUX_MEMORY_ERROR;
150 chunk->owner_ = 1; // Chunk is owner of data.
151 } else { // Don't copy data.
152 chunk->data_ = *data;
153 }
154 }
155 chunk->tag_ = tag;
156 return WEBP_MUX_OK;
157 }
158
ChunkSetNth(WebPChunk * chunk,WebPChunk ** chunk_list,uint32_t nth)159 WebPMuxError ChunkSetNth(WebPChunk* chunk, WebPChunk** chunk_list,
160 uint32_t nth) {
161 WebPChunk* new_chunk;
162
163 if (!ChunkSearchListToSet(chunk_list, nth, &chunk_list)) {
164 return WEBP_MUX_NOT_FOUND;
165 }
166
167 new_chunk = (WebPChunk*)WebPSafeMalloc(1ULL, sizeof(*new_chunk));
168 if (new_chunk == NULL) return WEBP_MUX_MEMORY_ERROR;
169 *new_chunk = *chunk;
170 chunk->owner_ = 0;
171 new_chunk->next_ = *chunk_list;
172 *chunk_list = new_chunk;
173 return WEBP_MUX_OK;
174 }
175
176 //------------------------------------------------------------------------------
177 // Chunk deletion method(s).
178
ChunkDelete(WebPChunk * const chunk)179 WebPChunk* ChunkDelete(WebPChunk* const chunk) {
180 WebPChunk* const next = ChunkRelease(chunk);
181 WebPSafeFree(chunk);
182 return next;
183 }
184
ChunkListDelete(WebPChunk ** const chunk_list)185 void ChunkListDelete(WebPChunk** const chunk_list) {
186 while (*chunk_list != NULL) {
187 *chunk_list = ChunkDelete(*chunk_list);
188 }
189 }
190
191 //------------------------------------------------------------------------------
192 // Chunk serialization methods.
193
ChunkEmit(const WebPChunk * const chunk,uint8_t * dst)194 static uint8_t* ChunkEmit(const WebPChunk* const chunk, uint8_t* dst) {
195 const size_t chunk_size = chunk->data_.size;
196 assert(chunk);
197 assert(chunk->tag_ != NIL_TAG);
198 PutLE32(dst + 0, chunk->tag_);
199 PutLE32(dst + TAG_SIZE, (uint32_t)chunk_size);
200 assert(chunk_size == (uint32_t)chunk_size);
201 memcpy(dst + CHUNK_HEADER_SIZE, chunk->data_.bytes, chunk_size);
202 if (chunk_size & 1)
203 dst[CHUNK_HEADER_SIZE + chunk_size] = 0; // Add padding.
204 return dst + ChunkDiskSize(chunk);
205 }
206
ChunkListEmit(const WebPChunk * chunk_list,uint8_t * dst)207 uint8_t* ChunkListEmit(const WebPChunk* chunk_list, uint8_t* dst) {
208 while (chunk_list != NULL) {
209 dst = ChunkEmit(chunk_list, dst);
210 chunk_list = chunk_list->next_;
211 }
212 return dst;
213 }
214
ChunkListDiskSize(const WebPChunk * chunk_list)215 size_t ChunkListDiskSize(const WebPChunk* chunk_list) {
216 size_t size = 0;
217 while (chunk_list != NULL) {
218 size += ChunkDiskSize(chunk_list);
219 chunk_list = chunk_list->next_;
220 }
221 return size;
222 }
223
224 //------------------------------------------------------------------------------
225 // Life of a MuxImage object.
226
MuxImageInit(WebPMuxImage * const wpi)227 void MuxImageInit(WebPMuxImage* const wpi) {
228 assert(wpi);
229 memset(wpi, 0, sizeof(*wpi));
230 }
231
MuxImageRelease(WebPMuxImage * const wpi)232 WebPMuxImage* MuxImageRelease(WebPMuxImage* const wpi) {
233 WebPMuxImage* next;
234 if (wpi == NULL) return NULL;
235 ChunkDelete(wpi->header_);
236 ChunkDelete(wpi->alpha_);
237 ChunkDelete(wpi->img_);
238 ChunkListDelete(&wpi->unknown_);
239
240 next = wpi->next_;
241 MuxImageInit(wpi);
242 return next;
243 }
244
245 //------------------------------------------------------------------------------
246 // MuxImage search methods.
247
248 // Get a reference to appropriate chunk list within an image given chunk tag.
GetChunkListFromId(const WebPMuxImage * const wpi,WebPChunkId id)249 static WebPChunk** GetChunkListFromId(const WebPMuxImage* const wpi,
250 WebPChunkId id) {
251 assert(wpi != NULL);
252 switch (id) {
253 case WEBP_CHUNK_ANMF: return (WebPChunk**)&wpi->header_;
254 case WEBP_CHUNK_ALPHA: return (WebPChunk**)&wpi->alpha_;
255 case WEBP_CHUNK_IMAGE: return (WebPChunk**)&wpi->img_;
256 default: return NULL;
257 }
258 }
259
MuxImageCount(const WebPMuxImage * wpi_list,WebPChunkId id)260 int MuxImageCount(const WebPMuxImage* wpi_list, WebPChunkId id) {
261 int count = 0;
262 const WebPMuxImage* current;
263 for (current = wpi_list; current != NULL; current = current->next_) {
264 if (id == WEBP_CHUNK_NIL) {
265 ++count; // Special case: count all images.
266 } else {
267 const WebPChunk* const wpi_chunk = *GetChunkListFromId(current, id);
268 if (wpi_chunk != NULL) {
269 const WebPChunkId wpi_chunk_id = ChunkGetIdFromTag(wpi_chunk->tag_);
270 if (wpi_chunk_id == id) ++count; // Count images with a matching 'id'.
271 }
272 }
273 }
274 return count;
275 }
276
277 // Outputs a pointer to 'prev_wpi->next_',
278 // where 'prev_wpi' is the pointer to the image at position (nth - 1).
279 // Returns true if nth image was found.
SearchImageToGetOrDelete(WebPMuxImage ** wpi_list,uint32_t nth,WebPMuxImage *** const location)280 static int SearchImageToGetOrDelete(WebPMuxImage** wpi_list, uint32_t nth,
281 WebPMuxImage*** const location) {
282 uint32_t count = 0;
283 assert(wpi_list);
284 *location = wpi_list;
285
286 if (nth == 0) {
287 nth = MuxImageCount(*wpi_list, WEBP_CHUNK_NIL);
288 if (nth == 0) return 0; // Not found.
289 }
290
291 while (*wpi_list != NULL) {
292 WebPMuxImage* const cur_wpi = *wpi_list;
293 ++count;
294 if (count == nth) return 1; // Found.
295 wpi_list = &cur_wpi->next_;
296 *location = wpi_list;
297 }
298 return 0; // Not found.
299 }
300
301 //------------------------------------------------------------------------------
302 // MuxImage writer methods.
303
MuxImagePush(const WebPMuxImage * wpi,WebPMuxImage ** wpi_list)304 WebPMuxError MuxImagePush(const WebPMuxImage* wpi, WebPMuxImage** wpi_list) {
305 WebPMuxImage* new_wpi;
306
307 while (*wpi_list != NULL) {
308 WebPMuxImage* const cur_wpi = *wpi_list;
309 if (cur_wpi->next_ == NULL) break;
310 wpi_list = &cur_wpi->next_;
311 }
312
313 new_wpi = (WebPMuxImage*)WebPSafeMalloc(1ULL, sizeof(*new_wpi));
314 if (new_wpi == NULL) return WEBP_MUX_MEMORY_ERROR;
315 *new_wpi = *wpi;
316 new_wpi->next_ = NULL;
317
318 if (*wpi_list != NULL) {
319 (*wpi_list)->next_ = new_wpi;
320 } else {
321 *wpi_list = new_wpi;
322 }
323 return WEBP_MUX_OK;
324 }
325
326 //------------------------------------------------------------------------------
327 // MuxImage deletion methods.
328
MuxImageDelete(WebPMuxImage * const wpi)329 WebPMuxImage* MuxImageDelete(WebPMuxImage* const wpi) {
330 // Delete the components of wpi. If wpi is NULL this is a noop.
331 WebPMuxImage* const next = MuxImageRelease(wpi);
332 WebPSafeFree(wpi);
333 return next;
334 }
335
MuxImageDeleteNth(WebPMuxImage ** wpi_list,uint32_t nth)336 WebPMuxError MuxImageDeleteNth(WebPMuxImage** wpi_list, uint32_t nth) {
337 assert(wpi_list);
338 if (!SearchImageToGetOrDelete(wpi_list, nth, &wpi_list)) {
339 return WEBP_MUX_NOT_FOUND;
340 }
341 *wpi_list = MuxImageDelete(*wpi_list);
342 return WEBP_MUX_OK;
343 }
344
345 //------------------------------------------------------------------------------
346 // MuxImage reader methods.
347
MuxImageGetNth(const WebPMuxImage ** wpi_list,uint32_t nth,WebPMuxImage ** wpi)348 WebPMuxError MuxImageGetNth(const WebPMuxImage** wpi_list, uint32_t nth,
349 WebPMuxImage** wpi) {
350 assert(wpi_list);
351 assert(wpi);
352 if (!SearchImageToGetOrDelete((WebPMuxImage**)wpi_list, nth,
353 (WebPMuxImage***)&wpi_list)) {
354 return WEBP_MUX_NOT_FOUND;
355 }
356 *wpi = (WebPMuxImage*)*wpi_list;
357 return WEBP_MUX_OK;
358 }
359
360 //------------------------------------------------------------------------------
361 // MuxImage serialization methods.
362
363 // Size of an image.
MuxImageDiskSize(const WebPMuxImage * const wpi)364 size_t MuxImageDiskSize(const WebPMuxImage* const wpi) {
365 size_t size = 0;
366 if (wpi->header_ != NULL) size += ChunkDiskSize(wpi->header_);
367 if (wpi->alpha_ != NULL) size += ChunkDiskSize(wpi->alpha_);
368 if (wpi->img_ != NULL) size += ChunkDiskSize(wpi->img_);
369 if (wpi->unknown_ != NULL) size += ChunkListDiskSize(wpi->unknown_);
370 return size;
371 }
372
373 // Special case as ANMF chunk encapsulates other image chunks.
ChunkEmitSpecial(const WebPChunk * const header,size_t total_size,uint8_t * dst)374 static uint8_t* ChunkEmitSpecial(const WebPChunk* const header,
375 size_t total_size, uint8_t* dst) {
376 const size_t header_size = header->data_.size;
377 const size_t offset_to_next = total_size - CHUNK_HEADER_SIZE;
378 assert(header->tag_ == kChunks[IDX_ANMF].tag);
379 PutLE32(dst + 0, header->tag_);
380 PutLE32(dst + TAG_SIZE, (uint32_t)offset_to_next);
381 assert(header_size == (uint32_t)header_size);
382 memcpy(dst + CHUNK_HEADER_SIZE, header->data_.bytes, header_size);
383 if (header_size & 1) {
384 dst[CHUNK_HEADER_SIZE + header_size] = 0; // Add padding.
385 }
386 return dst + ChunkDiskSize(header);
387 }
388
MuxImageEmit(const WebPMuxImage * const wpi,uint8_t * dst)389 uint8_t* MuxImageEmit(const WebPMuxImage* const wpi, uint8_t* dst) {
390 // Ordering of chunks to be emitted is strictly as follows:
391 // 1. ANMF chunk (if present).
392 // 2. ALPH chunk (if present).
393 // 3. VP8/VP8L chunk.
394 assert(wpi);
395 if (wpi->header_ != NULL) {
396 dst = ChunkEmitSpecial(wpi->header_, MuxImageDiskSize(wpi), dst);
397 }
398 if (wpi->alpha_ != NULL) dst = ChunkEmit(wpi->alpha_, dst);
399 if (wpi->img_ != NULL) dst = ChunkEmit(wpi->img_, dst);
400 if (wpi->unknown_ != NULL) dst = ChunkListEmit(wpi->unknown_, dst);
401 return dst;
402 }
403
404 //------------------------------------------------------------------------------
405 // Helper methods for mux.
406
MuxHasAlpha(const WebPMuxImage * images)407 int MuxHasAlpha(const WebPMuxImage* images) {
408 while (images != NULL) {
409 if (images->has_alpha_) return 1;
410 images = images->next_;
411 }
412 return 0;
413 }
414
MuxEmitRiffHeader(uint8_t * const data,size_t size)415 uint8_t* MuxEmitRiffHeader(uint8_t* const data, size_t size) {
416 PutLE32(data + 0, MKFOURCC('R', 'I', 'F', 'F'));
417 PutLE32(data + TAG_SIZE, (uint32_t)size - CHUNK_HEADER_SIZE);
418 assert(size == (uint32_t)size);
419 PutLE32(data + TAG_SIZE + CHUNK_SIZE_BYTES, MKFOURCC('W', 'E', 'B', 'P'));
420 return data + RIFF_HEADER_SIZE;
421 }
422
MuxGetChunkListFromId(const WebPMux * mux,WebPChunkId id)423 WebPChunk** MuxGetChunkListFromId(const WebPMux* mux, WebPChunkId id) {
424 assert(mux != NULL);
425 switch (id) {
426 case WEBP_CHUNK_VP8X: return (WebPChunk**)&mux->vp8x_;
427 case WEBP_CHUNK_ICCP: return (WebPChunk**)&mux->iccp_;
428 case WEBP_CHUNK_ANIM: return (WebPChunk**)&mux->anim_;
429 case WEBP_CHUNK_EXIF: return (WebPChunk**)&mux->exif_;
430 case WEBP_CHUNK_XMP: return (WebPChunk**)&mux->xmp_;
431 default: return (WebPChunk**)&mux->unknown_;
432 }
433 }
434
IsNotCompatible(int feature,int num_items)435 static int IsNotCompatible(int feature, int num_items) {
436 return (feature != 0) != (num_items > 0);
437 }
438
439 #define NO_FLAG ((WebPFeatureFlags)0)
440
441 // Test basic constraints:
442 // retrieval, maximum number of chunks by index (use -1 to skip)
443 // and feature incompatibility (use NO_FLAG to skip).
444 // On success returns WEBP_MUX_OK and stores the chunk count in *num.
ValidateChunk(const WebPMux * const mux,CHUNK_INDEX idx,WebPFeatureFlags feature,uint32_t vp8x_flags,int max,int * num)445 static WebPMuxError ValidateChunk(const WebPMux* const mux, CHUNK_INDEX idx,
446 WebPFeatureFlags feature,
447 uint32_t vp8x_flags,
448 int max, int* num) {
449 const WebPMuxError err =
450 WebPMuxNumChunks(mux, kChunks[idx].id, num);
451 if (err != WEBP_MUX_OK) return err;
452 if (max > -1 && *num > max) return WEBP_MUX_INVALID_ARGUMENT;
453 if (feature != NO_FLAG && IsNotCompatible(vp8x_flags & feature, *num)) {
454 return WEBP_MUX_INVALID_ARGUMENT;
455 }
456 return WEBP_MUX_OK;
457 }
458
MuxValidate(const WebPMux * const mux)459 WebPMuxError MuxValidate(const WebPMux* const mux) {
460 int num_iccp;
461 int num_exif;
462 int num_xmp;
463 int num_anim;
464 int num_frames;
465 int num_vp8x;
466 int num_images;
467 int num_alpha;
468 uint32_t flags;
469 WebPMuxError err;
470
471 // Verify mux is not NULL.
472 if (mux == NULL) return WEBP_MUX_INVALID_ARGUMENT;
473
474 // Verify mux has at least one image.
475 if (mux->images_ == NULL) return WEBP_MUX_INVALID_ARGUMENT;
476
477 err = WebPMuxGetFeatures(mux, &flags);
478 if (err != WEBP_MUX_OK) return err;
479
480 // At most one color profile chunk.
481 err = ValidateChunk(mux, IDX_ICCP, ICCP_FLAG, flags, 1, &num_iccp);
482 if (err != WEBP_MUX_OK) return err;
483
484 // At most one EXIF metadata.
485 err = ValidateChunk(mux, IDX_EXIF, EXIF_FLAG, flags, 1, &num_exif);
486 if (err != WEBP_MUX_OK) return err;
487
488 // At most one XMP metadata.
489 err = ValidateChunk(mux, IDX_XMP, XMP_FLAG, flags, 1, &num_xmp);
490 if (err != WEBP_MUX_OK) return err;
491
492 // Animation: ANIMATION_FLAG, ANIM chunk and ANMF chunk(s) are consistent.
493 // At most one ANIM chunk.
494 err = ValidateChunk(mux, IDX_ANIM, NO_FLAG, flags, 1, &num_anim);
495 if (err != WEBP_MUX_OK) return err;
496 err = ValidateChunk(mux, IDX_ANMF, NO_FLAG, flags, -1, &num_frames);
497 if (err != WEBP_MUX_OK) return err;
498
499 {
500 const int has_animation = !!(flags & ANIMATION_FLAG);
501 if (has_animation && (num_anim == 0 || num_frames == 0)) {
502 return WEBP_MUX_INVALID_ARGUMENT;
503 }
504 if (!has_animation && (num_anim == 1 || num_frames > 0)) {
505 return WEBP_MUX_INVALID_ARGUMENT;
506 }
507 if (!has_animation) {
508 const WebPMuxImage* images = mux->images_;
509 // There can be only one image.
510 if (images == NULL || images->next_ != NULL) {
511 return WEBP_MUX_INVALID_ARGUMENT;
512 }
513 // Size must match.
514 if (mux->canvas_width_ > 0) {
515 if (images->width_ != mux->canvas_width_ ||
516 images->height_ != mux->canvas_height_) {
517 return WEBP_MUX_INVALID_ARGUMENT;
518 }
519 }
520 }
521 }
522
523 // Verify either VP8X chunk is present OR there is only one elem in
524 // mux->images_.
525 err = ValidateChunk(mux, IDX_VP8X, NO_FLAG, flags, 1, &num_vp8x);
526 if (err != WEBP_MUX_OK) return err;
527 err = ValidateChunk(mux, IDX_VP8, NO_FLAG, flags, -1, &num_images);
528 if (err != WEBP_MUX_OK) return err;
529 if (num_vp8x == 0 && num_images != 1) return WEBP_MUX_INVALID_ARGUMENT;
530
531 // ALPHA_FLAG & alpha chunk(s) are consistent.
532 // Note: ALPHA_FLAG can be set when there is actually no Alpha data present.
533 if (MuxHasAlpha(mux->images_)) {
534 if (num_vp8x > 0) {
535 // VP8X chunk is present, so it should contain ALPHA_FLAG.
536 if (!(flags & ALPHA_FLAG)) return WEBP_MUX_INVALID_ARGUMENT;
537 } else {
538 // VP8X chunk is not present, so ALPH chunks should NOT be present either.
539 err = WebPMuxNumChunks(mux, WEBP_CHUNK_ALPHA, &num_alpha);
540 if (err != WEBP_MUX_OK) return err;
541 if (num_alpha > 0) return WEBP_MUX_INVALID_ARGUMENT;
542 }
543 }
544
545 return WEBP_MUX_OK;
546 }
547
548 #undef NO_FLAG
549
550 //------------------------------------------------------------------------------
551
552