Coverage Report

Created: 2024-06-18 06:05

/src/libpng/pngread.c
Line
Count
Source (jump to first uncovered line)
1
2
/* pngread.c - read a PNG file
3
 *
4
 * Copyright (c) 2018-2024 Cosmin Truta
5
 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6
 * Copyright (c) 1996-1997 Andreas Dilger
7
 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
8
 *
9
 * This code is released under the libpng license.
10
 * For conditions of distribution and use, see the disclaimer
11
 * and license in png.h
12
 *
13
 * This file contains routines that an application calls directly to
14
 * read a PNG file or stream.
15
 */
16
17
#include "pngpriv.h"
18
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
19
#  include <errno.h>
20
#endif
21
22
#ifdef PNG_READ_SUPPORTED
23
24
/* Create a PNG structure for reading, and allocate any memory needed. */
25
PNG_FUNCTION(png_structp,PNGAPI
26
png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
27
    png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
28
0
{
29
#ifndef PNG_USER_MEM_SUPPORTED
30
   png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
31
        error_fn, warn_fn, NULL, NULL, NULL);
32
#else
33
0
   return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
34
0
        warn_fn, NULL, NULL, NULL);
35
0
}
36
37
/* Alternate create PNG structure for reading, and allocate any memory
38
 * needed.
39
 */
40
PNG_FUNCTION(png_structp,PNGAPI
41
png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
42
    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
43
    png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
44
0
{
45
0
   png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
46
0
       error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
47
0
#endif /* USER_MEM */
48
49
0
   if (png_ptr != NULL)
50
0
   {
51
0
      png_ptr->mode = PNG_IS_READ_STRUCT;
52
53
      /* Added in libpng-1.6.0; this can be used to detect a read structure if
54
       * required (it will be zero in a write structure.)
55
       */
56
0
#     ifdef PNG_SEQUENTIAL_READ_SUPPORTED
57
0
         png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
58
0
#     endif
59
60
0
#     ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
61
0
         png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
62
63
         /* In stable builds only warn if an application error can be completely
64
          * handled.
65
          */
66
#        if PNG_RELEASE_BUILD
67
            png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
68
#        endif
69
0
#     endif
70
71
      /* TODO: delay this, it can be done in png_init_io (if the app doesn't
72
       * do it itself) avoiding setting the default function if it is not
73
       * required.
74
       */
75
0
      png_set_read_fn(png_ptr, NULL, NULL);
76
0
   }
77
78
0
   return png_ptr;
79
0
}
80
81
82
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
83
/* Read the information before the actual image data.  This has been
84
 * changed in v0.90 to allow reading a file that already has the magic
85
 * bytes read from the stream.  You can tell libpng how many bytes have
86
 * been read from the beginning of the stream (up to the maximum of 8)
87
 * via png_set_sig_bytes(), and we will only check the remaining bytes
88
 * here.  The application can then have access to the signature bytes we
89
 * read if it is determined that this isn't a valid PNG file.
90
 */
91
void PNGAPI
92
png_read_info(png_structrp png_ptr, png_inforp info_ptr)
93
0
{
94
0
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
95
0
   int keep;
96
0
#endif
97
98
0
   png_debug(1, "in png_read_info");
99
100
0
   if (png_ptr == NULL || info_ptr == NULL)
101
0
      return;
102
103
   /* Read and check the PNG file signature. */
104
0
   png_read_sig(png_ptr, info_ptr);
105
106
0
   for (;;)
107
0
   {
108
0
      png_uint_32 length = png_read_chunk_header(png_ptr);
109
0
      png_uint_32 chunk_name = png_ptr->chunk_name;
110
111
      /* IDAT logic needs to happen here to simplify getting the two flags
112
       * right.
113
       */
114
0
      if (chunk_name == png_IDAT)
115
0
      {
116
0
         if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
117
0
            png_chunk_error(png_ptr, "Missing IHDR before IDAT");
118
119
0
         else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
120
0
             (png_ptr->mode & PNG_HAVE_PLTE) == 0)
121
0
            png_chunk_error(png_ptr, "Missing PLTE before IDAT");
122
123
0
         else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
124
0
            png_chunk_benign_error(png_ptr, "Too many IDATs found");
125
126
0
         png_ptr->mode |= PNG_HAVE_IDAT;
127
0
      }
128
129
0
      else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
130
0
      {
131
0
         png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
132
0
         png_ptr->mode |= PNG_AFTER_IDAT;
133
0
      }
134
135
      /* This should be a binary subdivision search or a hash for
136
       * matching the chunk name rather than a linear search.
137
       */
138
0
      if (chunk_name == png_IHDR)
139
0
         png_handle_IHDR(png_ptr, info_ptr, length);
140
141
0
      else if (chunk_name == png_IEND)
142
0
         png_handle_IEND(png_ptr, info_ptr, length);
143
144
0
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
145
0
      else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
146
0
      {
147
0
         png_handle_unknown(png_ptr, info_ptr, length, keep);
148
149
0
         if (chunk_name == png_PLTE)
150
0
            png_ptr->mode |= PNG_HAVE_PLTE;
151
152
0
         else if (chunk_name == png_IDAT)
153
0
         {
154
0
            png_ptr->idat_size = 0; /* It has been consumed */
155
0
            break;
156
0
         }
157
0
      }
158
0
#endif
159
0
      else if (chunk_name == png_PLTE)
160
0
         png_handle_PLTE(png_ptr, info_ptr, length);
161
162
0
      else if (chunk_name == png_IDAT)
163
0
      {
164
0
         png_ptr->idat_size = length;
165
0
         break;
166
0
      }
167
168
0
#ifdef PNG_READ_bKGD_SUPPORTED
169
0
      else if (chunk_name == png_bKGD)
170
0
         png_handle_bKGD(png_ptr, info_ptr, length);
171
0
#endif
172
173
0
#ifdef PNG_READ_cHRM_SUPPORTED
174
0
      else if (chunk_name == png_cHRM)
175
0
         png_handle_cHRM(png_ptr, info_ptr, length);
176
0
#endif
177
178
0
#ifdef PNG_READ_eXIf_SUPPORTED
179
0
      else if (chunk_name == png_eXIf)
180
0
         png_handle_eXIf(png_ptr, info_ptr, length);
181
0
#endif
182
183
0
#ifdef PNG_READ_gAMA_SUPPORTED
184
0
      else if (chunk_name == png_gAMA)
185
0
         png_handle_gAMA(png_ptr, info_ptr, length);
186
0
#endif
187
188
0
#ifdef PNG_READ_hIST_SUPPORTED
189
0
      else if (chunk_name == png_hIST)
190
0
         png_handle_hIST(png_ptr, info_ptr, length);
191
0
#endif
192
193
0
#ifdef PNG_READ_oFFs_SUPPORTED
194
0
      else if (chunk_name == png_oFFs)
195
0
         png_handle_oFFs(png_ptr, info_ptr, length);
196
0
#endif
197
198
0
#ifdef PNG_READ_pCAL_SUPPORTED
199
0
      else if (chunk_name == png_pCAL)
200
0
         png_handle_pCAL(png_ptr, info_ptr, length);
201
0
#endif
202
203
0
#ifdef PNG_READ_sCAL_SUPPORTED
204
0
      else if (chunk_name == png_sCAL)
205
0
         png_handle_sCAL(png_ptr, info_ptr, length);
206
0
#endif
207
208
0
#ifdef PNG_READ_pHYs_SUPPORTED
209
0
      else if (chunk_name == png_pHYs)
210
0
         png_handle_pHYs(png_ptr, info_ptr, length);
211
0
#endif
212
213
0
#ifdef PNG_READ_sBIT_SUPPORTED
214
0
      else if (chunk_name == png_sBIT)
215
0
         png_handle_sBIT(png_ptr, info_ptr, length);
216
0
#endif
217
218
0
#ifdef PNG_READ_sRGB_SUPPORTED
219
0
      else if (chunk_name == png_sRGB)
220
0
         png_handle_sRGB(png_ptr, info_ptr, length);
221
0
#endif
222
223
0
#ifdef PNG_READ_iCCP_SUPPORTED
224
0
      else if (chunk_name == png_iCCP)
225
0
         png_handle_iCCP(png_ptr, info_ptr, length);
226
0
#endif
227
228
0
#ifdef PNG_READ_sPLT_SUPPORTED
229
0
      else if (chunk_name == png_sPLT)
230
0
         png_handle_sPLT(png_ptr, info_ptr, length);
231
0
#endif
232
233
0
#ifdef PNG_READ_tEXt_SUPPORTED
234
0
      else if (chunk_name == png_tEXt)
235
0
         png_handle_tEXt(png_ptr, info_ptr, length);
236
0
#endif
237
238
0
#ifdef PNG_READ_tIME_SUPPORTED
239
0
      else if (chunk_name == png_tIME)
240
0
         png_handle_tIME(png_ptr, info_ptr, length);
241
0
#endif
242
243
0
#ifdef PNG_READ_tRNS_SUPPORTED
244
0
      else if (chunk_name == png_tRNS)
245
0
         png_handle_tRNS(png_ptr, info_ptr, length);
246
0
#endif
247
248
0
#ifdef PNG_READ_zTXt_SUPPORTED
249
0
      else if (chunk_name == png_zTXt)
250
0
         png_handle_zTXt(png_ptr, info_ptr, length);
251
0
#endif
252
253
0
#ifdef PNG_READ_iTXt_SUPPORTED
254
0
      else if (chunk_name == png_iTXt)
255
0
         png_handle_iTXt(png_ptr, info_ptr, length);
256
0
#endif
257
258
0
      else
259
0
         png_handle_unknown(png_ptr, info_ptr, length,
260
0
             PNG_HANDLE_CHUNK_AS_DEFAULT);
261
0
   }
262
0
}
263
#endif /* SEQUENTIAL_READ */
264
265
/* Optional call to update the users info_ptr structure */
266
void PNGAPI
267
png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
268
0
{
269
0
   png_debug(1, "in png_read_update_info");
270
271
0
   if (png_ptr != NULL)
272
0
   {
273
0
      if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
274
0
      {
275
0
         png_read_start_row(png_ptr);
276
277
0
#        ifdef PNG_READ_TRANSFORMS_SUPPORTED
278
0
            png_read_transform_info(png_ptr, info_ptr);
279
#        else
280
            PNG_UNUSED(info_ptr)
281
#        endif
282
0
      }
283
284
      /* New in 1.6.0 this avoids the bug of doing the initializations twice */
285
0
      else
286
0
         png_app_error(png_ptr,
287
0
             "png_read_update_info/png_start_read_image: duplicate call");
288
0
   }
289
0
}
290
291
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
292
/* Initialize palette, background, etc, after transformations
293
 * are set, but before any reading takes place.  This allows
294
 * the user to obtain a gamma-corrected palette, for example.
295
 * If the user doesn't call this, we will do it ourselves.
296
 */
297
void PNGAPI
298
png_start_read_image(png_structrp png_ptr)
299
0
{
300
0
   png_debug(1, "in png_start_read_image");
301
302
0
   if (png_ptr != NULL)
303
0
   {
304
0
      if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
305
0
         png_read_start_row(png_ptr);
306
307
      /* New in 1.6.0 this avoids the bug of doing the initializations twice */
308
0
      else
309
0
         png_app_error(png_ptr,
310
0
             "png_start_read_image/png_read_update_info: duplicate call");
311
0
   }
312
0
}
313
#endif /* SEQUENTIAL_READ */
314
315
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
316
#ifdef PNG_MNG_FEATURES_SUPPORTED
317
/* Undoes intrapixel differencing,
318
 * NOTE: this is apparently only supported in the 'sequential' reader.
319
 */
320
static void
321
png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
322
0
{
323
0
   png_debug(1, "in png_do_read_intrapixel");
324
325
0
   if (
326
0
       (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
327
0
   {
328
0
      int bytes_per_pixel;
329
0
      png_uint_32 row_width = row_info->width;
330
331
0
      if (row_info->bit_depth == 8)
332
0
      {
333
0
         png_bytep rp;
334
0
         png_uint_32 i;
335
336
0
         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
337
0
            bytes_per_pixel = 3;
338
339
0
         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
340
0
            bytes_per_pixel = 4;
341
342
0
         else
343
0
            return;
344
345
0
         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
346
0
         {
347
0
            *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
348
0
            *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
349
0
         }
350
0
      }
351
0
      else if (row_info->bit_depth == 16)
352
0
      {
353
0
         png_bytep rp;
354
0
         png_uint_32 i;
355
356
0
         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
357
0
            bytes_per_pixel = 6;
358
359
0
         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
360
0
            bytes_per_pixel = 8;
361
362
0
         else
363
0
            return;
364
365
0
         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
366
0
         {
367
0
            png_uint_32 s0   = (png_uint_32)(*(rp    ) << 8) | *(rp + 1);
368
0
            png_uint_32 s1   = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
369
0
            png_uint_32 s2   = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
370
0
            png_uint_32 red  = (s0 + s1 + 65536) & 0xffff;
371
0
            png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
372
0
            *(rp    ) = (png_byte)((red >> 8) & 0xff);
373
0
            *(rp + 1) = (png_byte)(red & 0xff);
374
0
            *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
375
0
            *(rp + 5) = (png_byte)(blue & 0xff);
376
0
         }
377
0
      }
378
0
   }
379
0
}
380
#endif /* MNG_FEATURES */
381
382
void PNGAPI
383
png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
384
0
{
385
0
   png_row_info row_info;
386
387
0
   if (png_ptr == NULL)
388
0
      return;
389
390
0
   png_debug2(1, "in png_read_row (row %lu, pass %d)",
391
0
       (unsigned long)png_ptr->row_number, png_ptr->pass);
392
393
   /* png_read_start_row sets the information (in particular iwidth) for this
394
    * interlace pass.
395
    */
396
0
   if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
397
0
      png_read_start_row(png_ptr);
398
399
   /* 1.5.6: row_info moved out of png_struct to a local here. */
400
0
   row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
401
0
   row_info.color_type = png_ptr->color_type;
402
0
   row_info.bit_depth = png_ptr->bit_depth;
403
0
   row_info.channels = png_ptr->channels;
404
0
   row_info.pixel_depth = png_ptr->pixel_depth;
405
0
   row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
406
407
0
#ifdef PNG_WARNINGS_SUPPORTED
408
0
   if (png_ptr->row_number == 0 && png_ptr->pass == 0)
409
0
   {
410
   /* Check for transforms that have been set but were defined out */
411
#if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
412
   if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
413
      png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
414
#endif
415
416
#if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
417
   if ((png_ptr->transformations & PNG_FILLER) != 0)
418
      png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
419
#endif
420
421
#if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
422
    !defined(PNG_READ_PACKSWAP_SUPPORTED)
423
   if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
424
      png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
425
#endif
426
427
#if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
428
   if ((png_ptr->transformations & PNG_PACK) != 0)
429
      png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
430
#endif
431
432
#if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
433
   if ((png_ptr->transformations & PNG_SHIFT) != 0)
434
      png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
435
#endif
436
437
#if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
438
   if ((png_ptr->transformations & PNG_BGR) != 0)
439
      png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
440
#endif
441
442
#if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
443
   if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
444
      png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
445
#endif
446
0
   }
447
0
#endif /* WARNINGS */
448
449
0
#ifdef PNG_READ_INTERLACING_SUPPORTED
450
   /* If interlaced and we do not need a new row, combine row and return.
451
    * Notice that the pixels we have from previous rows have been transformed
452
    * already; we can only combine like with like (transformed or
453
    * untransformed) and, because of the libpng API for interlaced images, this
454
    * means we must transform before de-interlacing.
455
    */
456
0
   if (png_ptr->interlaced != 0 &&
457
0
       (png_ptr->transformations & PNG_INTERLACE) != 0)
458
0
   {
459
0
      switch (png_ptr->pass)
460
0
      {
461
0
         case 0:
462
0
            if (png_ptr->row_number & 0x07)
463
0
            {
464
0
               if (dsp_row != NULL)
465
0
                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
466
0
               png_read_finish_row(png_ptr);
467
0
               return;
468
0
            }
469
0
            break;
470
471
0
         case 1:
472
0
            if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
473
0
            {
474
0
               if (dsp_row != NULL)
475
0
                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
476
477
0
               png_read_finish_row(png_ptr);
478
0
               return;
479
0
            }
480
0
            break;
481
482
0
         case 2:
483
0
            if ((png_ptr->row_number & 0x07) != 4)
484
0
            {
485
0
               if (dsp_row != NULL && (png_ptr->row_number & 4))
486
0
                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
487
488
0
               png_read_finish_row(png_ptr);
489
0
               return;
490
0
            }
491
0
            break;
492
493
0
         case 3:
494
0
            if ((png_ptr->row_number & 3) || png_ptr->width < 3)
495
0
            {
496
0
               if (dsp_row != NULL)
497
0
                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
498
499
0
               png_read_finish_row(png_ptr);
500
0
               return;
501
0
            }
502
0
            break;
503
504
0
         case 4:
505
0
            if ((png_ptr->row_number & 3) != 2)
506
0
            {
507
0
               if (dsp_row != NULL && (png_ptr->row_number & 2))
508
0
                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
509
510
0
               png_read_finish_row(png_ptr);
511
0
               return;
512
0
            }
513
0
            break;
514
515
0
         case 5:
516
0
            if ((png_ptr->row_number & 1) || png_ptr->width < 2)
517
0
            {
518
0
               if (dsp_row != NULL)
519
0
                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
520
521
0
               png_read_finish_row(png_ptr);
522
0
               return;
523
0
            }
524
0
            break;
525
526
0
         default:
527
0
         case 6:
528
0
            if ((png_ptr->row_number & 1) == 0)
529
0
            {
530
0
               png_read_finish_row(png_ptr);
531
0
               return;
532
0
            }
533
0
            break;
534
0
      }
535
0
   }
536
0
#endif
537
538
0
   if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
539
0
      png_error(png_ptr, "Invalid attempt to read row data");
540
541
   /* Fill the row with IDAT data: */
542
0
   png_ptr->row_buf[0]=255; /* to force error if no data was found */
543
0
   png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
544
545
0
   if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
546
0
   {
547
0
      if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
548
0
         png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
549
0
             png_ptr->prev_row + 1, png_ptr->row_buf[0]);
550
0
      else
551
0
         png_error(png_ptr, "bad adaptive filter value");
552
0
   }
553
554
   /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
555
    * 1.5.6, while the buffer really is this big in current versions of libpng
556
    * it may not be in the future, so this was changed just to copy the
557
    * interlaced count:
558
    */
559
0
   memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
560
561
0
#ifdef PNG_MNG_FEATURES_SUPPORTED
562
0
   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
563
0
       (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
564
0
   {
565
      /* Intrapixel differencing */
566
0
      png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
567
0
   }
568
0
#endif
569
570
0
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
571
0
   if (png_ptr->transformations
572
0
#     ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
573
0
         || png_ptr->num_palette_max >= 0
574
0
#     endif
575
0
      )
576
0
      png_do_read_transformations(png_ptr, &row_info);
577
0
#endif
578
579
   /* The transformed pixel depth should match the depth now in row_info. */
580
0
   if (png_ptr->transformed_pixel_depth == 0)
581
0
   {
582
0
      png_ptr->transformed_pixel_depth = row_info.pixel_depth;
583
0
      if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
584
0
         png_error(png_ptr, "sequential row overflow");
585
0
   }
586
587
0
   else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
588
0
      png_error(png_ptr, "internal sequential row size calculation error");
589
590
0
#ifdef PNG_READ_INTERLACING_SUPPORTED
591
   /* Expand interlaced rows to full size */
592
0
   if (png_ptr->interlaced != 0 &&
593
0
      (png_ptr->transformations & PNG_INTERLACE) != 0)
594
0
   {
595
0
      if (png_ptr->pass < 6)
596
0
         png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
597
0
             png_ptr->transformations);
598
599
0
      if (dsp_row != NULL)
600
0
         png_combine_row(png_ptr, dsp_row, 1/*display*/);
601
602
0
      if (row != NULL)
603
0
         png_combine_row(png_ptr, row, 0/*row*/);
604
0
   }
605
606
0
   else
607
0
#endif
608
0
   {
609
0
      if (row != NULL)
610
0
         png_combine_row(png_ptr, row, -1/*ignored*/);
611
612
0
      if (dsp_row != NULL)
613
0
         png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
614
0
   }
615
0
   png_read_finish_row(png_ptr);
616
617
0
   if (png_ptr->read_row_fn != NULL)
618
0
      (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
619
620
0
}
621
#endif /* SEQUENTIAL_READ */
622
623
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
624
/* Read one or more rows of image data.  If the image is interlaced,
625
 * and png_set_interlace_handling() has been called, the rows need to
626
 * contain the contents of the rows from the previous pass.  If the
627
 * image has alpha or transparency, and png_handle_alpha()[*] has been
628
 * called, the rows contents must be initialized to the contents of the
629
 * screen.
630
 *
631
 * "row" holds the actual image, and pixels are placed in it
632
 * as they arrive.  If the image is displayed after each pass, it will
633
 * appear to "sparkle" in.  "display_row" can be used to display a
634
 * "chunky" progressive image, with finer detail added as it becomes
635
 * available.  If you do not want this "chunky" display, you may pass
636
 * NULL for display_row.  If you do not want the sparkle display, and
637
 * you have not called png_handle_alpha(), you may pass NULL for rows.
638
 * If you have called png_handle_alpha(), and the image has either an
639
 * alpha channel or a transparency chunk, you must provide a buffer for
640
 * rows.  In this case, you do not have to provide a display_row buffer
641
 * also, but you may.  If the image is not interlaced, or if you have
642
 * not called png_set_interlace_handling(), the display_row buffer will
643
 * be ignored, so pass NULL to it.
644
 *
645
 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
646
 */
647
648
void PNGAPI
649
png_read_rows(png_structrp png_ptr, png_bytepp row,
650
    png_bytepp display_row, png_uint_32 num_rows)
651
0
{
652
0
   png_uint_32 i;
653
0
   png_bytepp rp;
654
0
   png_bytepp dp;
655
656
0
   png_debug(1, "in png_read_rows");
657
658
0
   if (png_ptr == NULL)
659
0
      return;
660
661
0
   rp = row;
662
0
   dp = display_row;
663
0
   if (rp != NULL && dp != NULL)
664
0
      for (i = 0; i < num_rows; i++)
665
0
      {
666
0
         png_bytep rptr = *rp++;
667
0
         png_bytep dptr = *dp++;
668
669
0
         png_read_row(png_ptr, rptr, dptr);
670
0
      }
671
672
0
   else if (rp != NULL)
673
0
      for (i = 0; i < num_rows; i++)
674
0
      {
675
0
         png_bytep rptr = *rp;
676
0
         png_read_row(png_ptr, rptr, NULL);
677
0
         rp++;
678
0
      }
679
680
0
   else if (dp != NULL)
681
0
      for (i = 0; i < num_rows; i++)
682
0
      {
683
0
         png_bytep dptr = *dp;
684
0
         png_read_row(png_ptr, NULL, dptr);
685
0
         dp++;
686
0
      }
687
0
}
688
#endif /* SEQUENTIAL_READ */
689
690
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
691
/* Read the entire image.  If the image has an alpha channel or a tRNS
692
 * chunk, and you have called png_handle_alpha()[*], you will need to
693
 * initialize the image to the current image that PNG will be overlaying.
694
 * We set the num_rows again here, in case it was incorrectly set in
695
 * png_read_start_row() by a call to png_read_update_info() or
696
 * png_start_read_image() if png_set_interlace_handling() wasn't called
697
 * prior to either of these functions like it should have been.  You can
698
 * only call this function once.  If you desire to have an image for
699
 * each pass of a interlaced image, use png_read_rows() instead.
700
 *
701
 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
702
 */
703
void PNGAPI
704
png_read_image(png_structrp png_ptr, png_bytepp image)
705
0
{
706
0
   png_uint_32 i, image_height;
707
0
   int pass, j;
708
0
   png_bytepp rp;
709
710
0
   png_debug(1, "in png_read_image");
711
712
0
   if (png_ptr == NULL)
713
0
      return;
714
715
0
#ifdef PNG_READ_INTERLACING_SUPPORTED
716
0
   if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
717
0
   {
718
0
      pass = png_set_interlace_handling(png_ptr);
719
      /* And make sure transforms are initialized. */
720
0
      png_start_read_image(png_ptr);
721
0
   }
722
0
   else
723
0
   {
724
0
      if (png_ptr->interlaced != 0 &&
725
0
          (png_ptr->transformations & PNG_INTERLACE) == 0)
726
0
      {
727
         /* Caller called png_start_read_image or png_read_update_info without
728
          * first turning on the PNG_INTERLACE transform.  We can fix this here,
729
          * but the caller should do it!
730
          */
731
0
         png_warning(png_ptr, "Interlace handling should be turned on when "
732
0
             "using png_read_image");
733
         /* Make sure this is set correctly */
734
0
         png_ptr->num_rows = png_ptr->height;
735
0
      }
736
737
      /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
738
       * the above error case.
739
       */
740
0
      pass = png_set_interlace_handling(png_ptr);
741
0
   }
742
#else
743
   if (png_ptr->interlaced)
744
      png_error(png_ptr,
745
          "Cannot read interlaced image -- interlace handler disabled");
746
747
   pass = 1;
748
#endif
749
750
0
   image_height=png_ptr->height;
751
752
0
   for (j = 0; j < pass; j++)
753
0
   {
754
0
      rp = image;
755
0
      for (i = 0; i < image_height; i++)
756
0
      {
757
0
         png_read_row(png_ptr, *rp, NULL);
758
0
         rp++;
759
0
      }
760
0
   }
761
0
}
762
#endif /* SEQUENTIAL_READ */
763
764
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
765
/* Read the end of the PNG file.  Will not read past the end of the
766
 * file, will verify the end is accurate, and will read any comments
767
 * or time information at the end of the file, if info is not NULL.
768
 */
769
void PNGAPI
770
png_read_end(png_structrp png_ptr, png_inforp info_ptr)
771
0
{
772
0
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
773
0
   int keep;
774
0
#endif
775
776
0
   png_debug(1, "in png_read_end");
777
778
0
   if (png_ptr == NULL)
779
0
      return;
780
781
   /* If png_read_end is called in the middle of reading the rows there may
782
    * still be pending IDAT data and an owned zstream.  Deal with this here.
783
    */
784
0
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
785
0
   if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
786
0
#endif
787
0
      png_read_finish_IDAT(png_ptr);
788
789
0
#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
790
   /* Report invalid palette index; added at libng-1.5.10 */
791
0
   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
792
0
       png_ptr->num_palette_max >= png_ptr->num_palette)
793
0
      png_benign_error(png_ptr, "Read palette index exceeding num_palette");
794
0
#endif
795
796
0
   do
797
0
   {
798
0
      png_uint_32 length = png_read_chunk_header(png_ptr);
799
0
      png_uint_32 chunk_name = png_ptr->chunk_name;
800
801
0
      if (chunk_name != png_IDAT)
802
0
         png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
803
804
0
      if (chunk_name == png_IEND)
805
0
         png_handle_IEND(png_ptr, info_ptr, length);
806
807
0
      else if (chunk_name == png_IHDR)
808
0
         png_handle_IHDR(png_ptr, info_ptr, length);
809
810
0
      else if (info_ptr == NULL)
811
0
         png_crc_finish(png_ptr, length);
812
813
0
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
814
0
      else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
815
0
      {
816
0
         if (chunk_name == png_IDAT)
817
0
         {
818
0
            if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
819
0
                || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
820
0
               png_benign_error(png_ptr, ".Too many IDATs found");
821
0
         }
822
0
         png_handle_unknown(png_ptr, info_ptr, length, keep);
823
0
         if (chunk_name == png_PLTE)
824
0
            png_ptr->mode |= PNG_HAVE_PLTE;
825
0
      }
826
0
#endif
827
828
0
      else if (chunk_name == png_IDAT)
829
0
      {
830
         /* Zero length IDATs are legal after the last IDAT has been
831
          * read, but not after other chunks have been read.  1.6 does not
832
          * always read all the deflate data; specifically it cannot be relied
833
          * upon to read the Adler32 at the end.  If it doesn't ignore IDAT
834
          * chunks which are longer than zero as well:
835
          */
836
0
         if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
837
0
             || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
838
0
            png_benign_error(png_ptr, "..Too many IDATs found");
839
840
0
         png_crc_finish(png_ptr, length);
841
0
      }
842
0
      else if (chunk_name == png_PLTE)
843
0
         png_handle_PLTE(png_ptr, info_ptr, length);
844
845
0
#ifdef PNG_READ_bKGD_SUPPORTED
846
0
      else if (chunk_name == png_bKGD)
847
0
         png_handle_bKGD(png_ptr, info_ptr, length);
848
0
#endif
849
850
0
#ifdef PNG_READ_cHRM_SUPPORTED
851
0
      else if (chunk_name == png_cHRM)
852
0
         png_handle_cHRM(png_ptr, info_ptr, length);
853
0
#endif
854
855
0
#ifdef PNG_READ_eXIf_SUPPORTED
856
0
      else if (chunk_name == png_eXIf)
857
0
         png_handle_eXIf(png_ptr, info_ptr, length);
858
0
#endif
859
860
0
#ifdef PNG_READ_gAMA_SUPPORTED
861
0
      else if (chunk_name == png_gAMA)
862
0
         png_handle_gAMA(png_ptr, info_ptr, length);
863
0
#endif
864
865
0
#ifdef PNG_READ_hIST_SUPPORTED
866
0
      else if (chunk_name == png_hIST)
867
0
         png_handle_hIST(png_ptr, info_ptr, length);
868
0
#endif
869
870
0
#ifdef PNG_READ_oFFs_SUPPORTED
871
0
      else if (chunk_name == png_oFFs)
872
0
         png_handle_oFFs(png_ptr, info_ptr, length);
873
0
#endif
874
875
0
#ifdef PNG_READ_pCAL_SUPPORTED
876
0
      else if (chunk_name == png_pCAL)
877
0
         png_handle_pCAL(png_ptr, info_ptr, length);
878
0
#endif
879
880
0
#ifdef PNG_READ_sCAL_SUPPORTED
881
0
      else if (chunk_name == png_sCAL)
882
0
         png_handle_sCAL(png_ptr, info_ptr, length);
883
0
#endif
884
885
0
#ifdef PNG_READ_pHYs_SUPPORTED
886
0
      else if (chunk_name == png_pHYs)
887
0
         png_handle_pHYs(png_ptr, info_ptr, length);
888
0
#endif
889
890
0
#ifdef PNG_READ_sBIT_SUPPORTED
891
0
      else if (chunk_name == png_sBIT)
892
0
         png_handle_sBIT(png_ptr, info_ptr, length);
893
0
#endif
894
895
0
#ifdef PNG_READ_sRGB_SUPPORTED
896
0
      else if (chunk_name == png_sRGB)
897
0
         png_handle_sRGB(png_ptr, info_ptr, length);
898
0
#endif
899
900
0
#ifdef PNG_READ_iCCP_SUPPORTED
901
0
      else if (chunk_name == png_iCCP)
902
0
         png_handle_iCCP(png_ptr, info_ptr, length);
903
0
#endif
904
905
0
#ifdef PNG_READ_sPLT_SUPPORTED
906
0
      else if (chunk_name == png_sPLT)
907
0
         png_handle_sPLT(png_ptr, info_ptr, length);
908
0
#endif
909
910
0
#ifdef PNG_READ_tEXt_SUPPORTED
911
0
      else if (chunk_name == png_tEXt)
912
0
         png_handle_tEXt(png_ptr, info_ptr, length);
913
0
#endif
914
915
0
#ifdef PNG_READ_tIME_SUPPORTED
916
0
      else if (chunk_name == png_tIME)
917
0
         png_handle_tIME(png_ptr, info_ptr, length);
918
0
#endif
919
920
0
#ifdef PNG_READ_tRNS_SUPPORTED
921
0
      else if (chunk_name == png_tRNS)
922
0
         png_handle_tRNS(png_ptr, info_ptr, length);
923
0
#endif
924
925
0
#ifdef PNG_READ_zTXt_SUPPORTED
926
0
      else if (chunk_name == png_zTXt)
927
0
         png_handle_zTXt(png_ptr, info_ptr, length);
928
0
#endif
929
930
0
#ifdef PNG_READ_iTXt_SUPPORTED
931
0
      else if (chunk_name == png_iTXt)
932
0
         png_handle_iTXt(png_ptr, info_ptr, length);
933
0
#endif
934
935
0
      else
936
0
         png_handle_unknown(png_ptr, info_ptr, length,
937
0
             PNG_HANDLE_CHUNK_AS_DEFAULT);
938
0
   } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
939
0
}
940
#endif /* SEQUENTIAL_READ */
941
942
/* Free all memory used in the read struct */
943
static void
944
png_read_destroy(png_structrp png_ptr)
945
0
{
946
0
   png_debug(1, "in png_read_destroy");
947
948
0
#ifdef PNG_READ_GAMMA_SUPPORTED
949
0
   png_destroy_gamma_table(png_ptr);
950
0
#endif
951
952
0
   png_free(png_ptr, png_ptr->big_row_buf);
953
0
   png_ptr->big_row_buf = NULL;
954
0
   png_free(png_ptr, png_ptr->big_prev_row);
955
0
   png_ptr->big_prev_row = NULL;
956
0
   png_free(png_ptr, png_ptr->read_buffer);
957
0
   png_ptr->read_buffer = NULL;
958
959
0
#ifdef PNG_READ_QUANTIZE_SUPPORTED
960
0
   png_free(png_ptr, png_ptr->palette_lookup);
961
0
   png_ptr->palette_lookup = NULL;
962
0
   png_free(png_ptr, png_ptr->quantize_index);
963
0
   png_ptr->quantize_index = NULL;
964
0
#endif
965
966
0
   if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
967
0
   {
968
0
      png_zfree(png_ptr, png_ptr->palette);
969
0
      png_ptr->palette = NULL;
970
0
   }
971
0
   png_ptr->free_me &= ~PNG_FREE_PLTE;
972
973
0
#if defined(PNG_tRNS_SUPPORTED) || \
974
0
    defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
975
0
   if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
976
0
   {
977
0
      png_free(png_ptr, png_ptr->trans_alpha);
978
0
      png_ptr->trans_alpha = NULL;
979
0
   }
980
0
   png_ptr->free_me &= ~PNG_FREE_TRNS;
981
0
#endif
982
983
0
   inflateEnd(&png_ptr->zstream);
984
985
0
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
986
0
   png_free(png_ptr, png_ptr->save_buffer);
987
0
   png_ptr->save_buffer = NULL;
988
0
#endif
989
990
0
#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
991
0
   defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
992
0
   png_free(png_ptr, png_ptr->unknown_chunk.data);
993
0
   png_ptr->unknown_chunk.data = NULL;
994
0
#endif
995
996
0
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
997
0
   png_free(png_ptr, png_ptr->chunk_list);
998
0
   png_ptr->chunk_list = NULL;
999
0
#endif
1000
1001
0
#if defined(PNG_READ_EXPAND_SUPPORTED) && \
1002
0
    defined(PNG_ARM_NEON_IMPLEMENTATION)
1003
0
   png_free(png_ptr, png_ptr->riffled_palette);
1004
0
   png_ptr->riffled_palette = NULL;
1005
0
#endif
1006
1007
   /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
1008
    * callbacks are still set at this point.  They are required to complete the
1009
    * destruction of the png_struct itself.
1010
    */
1011
0
}
1012
1013
/* Free all memory used by the read */
1014
void PNGAPI
1015
png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
1016
    png_infopp end_info_ptr_ptr)
1017
0
{
1018
0
   png_structrp png_ptr = NULL;
1019
1020
0
   png_debug(1, "in png_destroy_read_struct");
1021
1022
0
   if (png_ptr_ptr != NULL)
1023
0
      png_ptr = *png_ptr_ptr;
1024
1025
0
   if (png_ptr == NULL)
1026
0
      return;
1027
1028
   /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
1029
    * behavior.  Prior to 1.6.0 libpng did extra 'info' destruction in this API.
1030
    * The extra was, apparently, unnecessary yet this hides memory leak bugs.
1031
    */
1032
0
   png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
1033
0
   png_destroy_info_struct(png_ptr, info_ptr_ptr);
1034
1035
0
   *png_ptr_ptr = NULL;
1036
0
   png_read_destroy(png_ptr);
1037
0
   png_destroy_png_struct(png_ptr);
1038
0
}
1039
1040
void PNGAPI
1041
png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
1042
0
{
1043
0
   if (png_ptr == NULL)
1044
0
      return;
1045
1046
0
   png_ptr->read_row_fn = read_row_fn;
1047
0
}
1048
1049
1050
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1051
#ifdef PNG_INFO_IMAGE_SUPPORTED
1052
void PNGAPI
1053
png_read_png(png_structrp png_ptr, png_inforp info_ptr,
1054
    int transforms, voidp params)
1055
0
{
1056
0
   png_debug(1, "in png_read_png");
1057
1058
0
   if (png_ptr == NULL || info_ptr == NULL)
1059
0
      return;
1060
1061
   /* png_read_info() gives us all of the information from the
1062
    * PNG file before the first IDAT (image data chunk).
1063
    */
1064
0
   png_read_info(png_ptr, info_ptr);
1065
0
   if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
1066
0
      png_error(png_ptr, "Image is too high to process with png_read_png()");
1067
1068
   /* -------------- image transformations start here ------------------- */
1069
   /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
1070
    * is not implemented.  This will only happen in de-configured (non-default)
1071
    * libpng builds.  The results can be unexpected - png_read_png may return
1072
    * short or mal-formed rows because the transform is skipped.
1073
    */
1074
1075
   /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1076
    */
1077
0
   if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
1078
      /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1079
       * did in earlier versions, while "scale_16" is now more accurate.
1080
       */
1081
0
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1082
0
      png_set_scale_16(png_ptr);
1083
#else
1084
      png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
1085
#endif
1086
1087
   /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1088
    * latter by doing SCALE first.  This is ok and allows apps not to check for
1089
    * which is supported to get the right answer.
1090
    */
1091
0
   if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
1092
0
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1093
0
      png_set_strip_16(png_ptr);
1094
#else
1095
      png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
1096
#endif
1097
1098
   /* Strip alpha bytes from the input data without combining with
1099
    * the background (not recommended).
1100
    */
1101
0
   if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
1102
0
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1103
0
      png_set_strip_alpha(png_ptr);
1104
#else
1105
      png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
1106
#endif
1107
1108
   /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1109
    * byte into separate bytes (useful for paletted and grayscale images).
1110
    */
1111
0
   if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1112
0
#ifdef PNG_READ_PACK_SUPPORTED
1113
0
      png_set_packing(png_ptr);
1114
#else
1115
      png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1116
#endif
1117
1118
   /* Change the order of packed pixels to least significant bit first
1119
    * (not useful if you are using png_set_packing).
1120
    */
1121
0
   if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1122
0
#ifdef PNG_READ_PACKSWAP_SUPPORTED
1123
0
      png_set_packswap(png_ptr);
1124
#else
1125
      png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1126
#endif
1127
1128
   /* Expand paletted colors into true RGB triplets
1129
    * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1130
    * Expand paletted or RGB images with transparency to full alpha
1131
    * channels so the data will be available as RGBA quartets.
1132
    */
1133
0
   if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
1134
0
#ifdef PNG_READ_EXPAND_SUPPORTED
1135
0
      png_set_expand(png_ptr);
1136
#else
1137
      png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
1138
#endif
1139
1140
   /* We don't handle background color or gamma transformation or quantizing.
1141
    */
1142
1143
   /* Invert monochrome files to have 0 as white and 1 as black
1144
    */
1145
0
   if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1146
0
#ifdef PNG_READ_INVERT_SUPPORTED
1147
0
      png_set_invert_mono(png_ptr);
1148
#else
1149
      png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1150
#endif
1151
1152
   /* If you want to shift the pixel values from the range [0,255] or
1153
    * [0,65535] to the original [0,7] or [0,31], or whatever range the
1154
    * colors were originally in:
1155
    */
1156
0
   if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1157
0
#ifdef PNG_READ_SHIFT_SUPPORTED
1158
0
      if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1159
0
         png_set_shift(png_ptr, &info_ptr->sig_bit);
1160
#else
1161
      png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1162
#endif
1163
1164
   /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1165
0
   if ((transforms & PNG_TRANSFORM_BGR) != 0)
1166
0
#ifdef PNG_READ_BGR_SUPPORTED
1167
0
      png_set_bgr(png_ptr);
1168
#else
1169
      png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1170
#endif
1171
1172
   /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1173
0
   if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1174
0
#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1175
0
      png_set_swap_alpha(png_ptr);
1176
#else
1177
      png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1178
#endif
1179
1180
   /* Swap bytes of 16-bit files to least significant byte first */
1181
0
   if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1182
0
#ifdef PNG_READ_SWAP_SUPPORTED
1183
0
      png_set_swap(png_ptr);
1184
#else
1185
      png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1186
#endif
1187
1188
/* Added at libpng-1.2.41 */
1189
   /* Invert the alpha channel from opacity to transparency */
1190
0
   if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1191
0
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1192
0
      png_set_invert_alpha(png_ptr);
1193
#else
1194
      png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1195
#endif
1196
1197
/* Added at libpng-1.2.41 */
1198
   /* Expand grayscale image to RGB */
1199
0
   if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
1200
0
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1201
0
      png_set_gray_to_rgb(png_ptr);
1202
#else
1203
      png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
1204
#endif
1205
1206
/* Added at libpng-1.5.4 */
1207
0
   if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
1208
0
#ifdef PNG_READ_EXPAND_16_SUPPORTED
1209
0
      png_set_expand_16(png_ptr);
1210
#else
1211
      png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
1212
#endif
1213
1214
   /* We don't handle adding filler bytes */
1215
1216
   /* We use png_read_image and rely on that for interlace handling, but we also
1217
    * call png_read_update_info therefore must turn on interlace handling now:
1218
    */
1219
0
   (void)png_set_interlace_handling(png_ptr);
1220
1221
   /* Optional call to gamma correct and add the background to the palette
1222
    * and update info structure.  REQUIRED if you are expecting libpng to
1223
    * update the palette for you (i.e., you selected such a transform above).
1224
    */
1225
0
   png_read_update_info(png_ptr, info_ptr);
1226
1227
   /* -------------- image transformations end here ------------------- */
1228
1229
0
   png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1230
0
   if (info_ptr->row_pointers == NULL)
1231
0
   {
1232
0
      png_uint_32 iptr;
1233
1234
0
      info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
1235
0
          info_ptr->height * (sizeof (png_bytep))));
1236
1237
0
      for (iptr=0; iptr<info_ptr->height; iptr++)
1238
0
         info_ptr->row_pointers[iptr] = NULL;
1239
1240
0
      info_ptr->free_me |= PNG_FREE_ROWS;
1241
1242
0
      for (iptr = 0; iptr < info_ptr->height; iptr++)
1243
0
         info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
1244
0
             png_malloc(png_ptr, info_ptr->rowbytes));
1245
0
   }
1246
1247
0
   png_read_image(png_ptr, info_ptr->row_pointers);
1248
0
   info_ptr->valid |= PNG_INFO_IDAT;
1249
1250
   /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1251
0
   png_read_end(png_ptr, info_ptr);
1252
1253
0
   PNG_UNUSED(params)
1254
0
}
1255
#endif /* INFO_IMAGE */
1256
#endif /* SEQUENTIAL_READ */
1257
1258
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
1259
/* SIMPLIFIED READ
1260
 *
1261
 * This code currently relies on the sequential reader, though it could easily
1262
 * be made to work with the progressive one.
1263
 */
1264
/* Arguments to png_image_finish_read: */
1265
1266
/* Encoding of PNG data (used by the color-map code) */
1267
0
#  define P_NOTSET  0 /* File encoding not yet known */
1268
0
#  define P_sRGB    1 /* 8-bit encoded to sRGB gamma */
1269
0
#  define P_LINEAR  2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
1270
0
#  define P_FILE    3 /* 8-bit encoded to file gamma, not sRGB or linear */
1271
0
#  define P_LINEAR8 4 /* 8-bit linear: only from a file value */
1272
1273
/* Color-map processing: after libpng has run on the PNG image further
1274
 * processing may be needed to convert the data to color-map indices.
1275
 */
1276
0
#define PNG_CMAP_NONE      0
1277
0
#define PNG_CMAP_GA        1 /* Process GA data to a color-map with alpha */
1278
0
#define PNG_CMAP_TRANS     2 /* Process GA data to a background index */
1279
0
#define PNG_CMAP_RGB       3 /* Process RGB data */
1280
0
#define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
1281
1282
/* The following document where the background is for each processing case. */
1283
0
#define PNG_CMAP_NONE_BACKGROUND      256
1284
0
#define PNG_CMAP_GA_BACKGROUND        231
1285
0
#define PNG_CMAP_TRANS_BACKGROUND     254
1286
0
#define PNG_CMAP_RGB_BACKGROUND       256
1287
0
#define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
1288
1289
typedef struct
1290
{
1291
   /* Arguments: */
1292
   png_imagep image;
1293
   png_voidp  buffer;
1294
   png_int_32 row_stride;
1295
   png_voidp  colormap;
1296
   png_const_colorp background;
1297
   /* Local variables: */
1298
   png_voidp       local_row;
1299
   png_voidp       first_row;
1300
   ptrdiff_t       row_bytes;           /* step between rows */
1301
   int             file_encoding;       /* E_ values above */
1302
   png_fixed_point gamma_to_linear;     /* For P_FILE, reciprocal of gamma */
1303
   int             colormap_processing; /* PNG_CMAP_ values above */
1304
} png_image_read_control;
1305
1306
/* Do all the *safe* initialization - 'safe' means that png_error won't be
1307
 * called, so setting up the jmp_buf is not required.  This means that anything
1308
 * called from here must *not* call png_malloc - it has to call png_malloc_warn
1309
 * instead so that control is returned safely back to this routine.
1310
 */
1311
static int
1312
png_image_read_init(png_imagep image)
1313
0
{
1314
0
   if (image->opaque == NULL)
1315
0
   {
1316
0
      png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
1317
0
          png_safe_error, png_safe_warning);
1318
1319
      /* And set the rest of the structure to NULL to ensure that the various
1320
       * fields are consistent.
1321
       */
1322
0
      memset(image, 0, (sizeof *image));
1323
0
      image->version = PNG_IMAGE_VERSION;
1324
1325
0
      if (png_ptr != NULL)
1326
0
      {
1327
0
         png_infop info_ptr = png_create_info_struct(png_ptr);
1328
1329
0
         if (info_ptr != NULL)
1330
0
         {
1331
0
            png_controlp control = png_voidcast(png_controlp,
1332
0
                png_malloc_warn(png_ptr, (sizeof *control)));
1333
1334
0
            if (control != NULL)
1335
0
            {
1336
0
               memset(control, 0, (sizeof *control));
1337
1338
0
               control->png_ptr = png_ptr;
1339
0
               control->info_ptr = info_ptr;
1340
0
               control->for_write = 0;
1341
1342
0
               image->opaque = control;
1343
0
               return 1;
1344
0
            }
1345
1346
            /* Error clean up */
1347
0
            png_destroy_info_struct(png_ptr, &info_ptr);
1348
0
         }
1349
1350
0
         png_destroy_read_struct(&png_ptr, NULL, NULL);
1351
0
      }
1352
1353
0
      return png_image_error(image, "png_image_read: out of memory");
1354
0
   }
1355
1356
0
   return png_image_error(image, "png_image_read: opaque pointer not NULL");
1357
0
}
1358
1359
/* Utility to find the base format of a PNG file from a png_struct. */
1360
static png_uint_32
1361
png_image_format(png_structrp png_ptr)
1362
0
{
1363
0
   png_uint_32 format = 0;
1364
1365
0
   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1366
0
      format |= PNG_FORMAT_FLAG_COLOR;
1367
1368
0
   if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
1369
0
      format |= PNG_FORMAT_FLAG_ALPHA;
1370
1371
   /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
1372
    * sets the png_struct fields; that's all we are interested in here.  The
1373
    * precise interaction with an app call to png_set_tRNS and PNG file reading
1374
    * is unclear.
1375
    */
1376
0
   else if (png_ptr->num_trans > 0)
1377
0
      format |= PNG_FORMAT_FLAG_ALPHA;
1378
1379
0
   if (png_ptr->bit_depth == 16)
1380
0
      format |= PNG_FORMAT_FLAG_LINEAR;
1381
1382
0
   if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
1383
0
      format |= PNG_FORMAT_FLAG_COLORMAP;
1384
1385
0
   return format;
1386
0
}
1387
1388
/* Is the given gamma significantly different from sRGB?  The test is the same
1389
 * one used in pngrtran.c when deciding whether to do gamma correction.  The
1390
 * arithmetic optimizes the division by using the fact that the inverse of the
1391
 * file sRGB gamma is 2.2
1392
 */
1393
static int
1394
png_gamma_not_sRGB(png_fixed_point g)
1395
0
{
1396
0
   if (g < PNG_FP_1)
1397
0
   {
1398
      /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
1399
0
      if (g == 0)
1400
0
         return 0;
1401
1402
0
      return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
1403
0
   }
1404
1405
0
   return 1;
1406
0
}
1407
1408
/* Do the main body of a 'png_image_begin_read' function; read the PNG file
1409
 * header and fill in all the information.  This is executed in a safe context,
1410
 * unlike the init routine above.
1411
 */
1412
static int
1413
png_image_read_header(png_voidp argument)
1414
0
{
1415
0
   png_imagep image = png_voidcast(png_imagep, argument);
1416
0
   png_structrp png_ptr = image->opaque->png_ptr;
1417
0
   png_inforp info_ptr = image->opaque->info_ptr;
1418
1419
0
#ifdef PNG_BENIGN_ERRORS_SUPPORTED
1420
0
   png_set_benign_errors(png_ptr, 1/*warn*/);
1421
0
#endif
1422
0
   png_read_info(png_ptr, info_ptr);
1423
1424
   /* Do this the fast way; just read directly out of png_struct. */
1425
0
   image->width = png_ptr->width;
1426
0
   image->height = png_ptr->height;
1427
1428
0
   {
1429
0
      png_uint_32 format = png_image_format(png_ptr);
1430
1431
0
      image->format = format;
1432
1433
0
#ifdef PNG_COLORSPACE_SUPPORTED
1434
      /* Does the colorspace match sRGB?  If there is no color endpoint
1435
       * (colorant) information assume yes, otherwise require the
1436
       * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set.  If the
1437
       * colorspace has been determined to be invalid ignore it.
1438
       */
1439
0
      if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
1440
0
         & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
1441
0
            PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
1442
0
         image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
1443
0
#endif
1444
0
   }
1445
1446
   /* We need the maximum number of entries regardless of the format the
1447
    * application sets here.
1448
    */
1449
0
   {
1450
0
      png_uint_32 cmap_entries;
1451
1452
0
      switch (png_ptr->color_type)
1453
0
      {
1454
0
         case PNG_COLOR_TYPE_GRAY:
1455
0
            cmap_entries = 1U << png_ptr->bit_depth;
1456
0
            break;
1457
1458
0
         case PNG_COLOR_TYPE_PALETTE:
1459
0
            cmap_entries = (png_uint_32)png_ptr->num_palette;
1460
0
            break;
1461
1462
0
         default:
1463
0
            cmap_entries = 256;
1464
0
            break;
1465
0
      }
1466
1467
0
      if (cmap_entries > 256)
1468
0
         cmap_entries = 256;
1469
1470
0
      image->colormap_entries = cmap_entries;
1471
0
   }
1472
1473
0
   return 1;
1474
0
}
1475
1476
#ifdef PNG_STDIO_SUPPORTED
1477
int PNGAPI
1478
png_image_begin_read_from_stdio(png_imagep image, FILE* file)
1479
0
{
1480
0
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
1481
0
   {
1482
0
      if (file != NULL)
1483
0
      {
1484
0
         if (png_image_read_init(image) != 0)
1485
0
         {
1486
            /* This is slightly evil, but png_init_io doesn't do anything other
1487
             * than this and we haven't changed the standard IO functions so
1488
             * this saves a 'safe' function.
1489
             */
1490
0
            image->opaque->png_ptr->io_ptr = file;
1491
0
            return png_safe_execute(image, png_image_read_header, image);
1492
0
         }
1493
0
      }
1494
1495
0
      else
1496
0
         return png_image_error(image,
1497
0
             "png_image_begin_read_from_stdio: invalid argument");
1498
0
   }
1499
1500
0
   else if (image != NULL)
1501
0
      return png_image_error(image,
1502
0
          "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
1503
1504
0
   return 0;
1505
0
}
1506
1507
int PNGAPI
1508
png_image_begin_read_from_file(png_imagep image, const char *file_name)
1509
0
{
1510
0
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
1511
0
   {
1512
0
      if (file_name != NULL)
1513
0
      {
1514
0
         FILE *fp = fopen(file_name, "rb");
1515
1516
0
         if (fp != NULL)
1517
0
         {
1518
0
            if (png_image_read_init(image) != 0)
1519
0
            {
1520
0
               image->opaque->png_ptr->io_ptr = fp;
1521
0
               image->opaque->owned_file = 1;
1522
0
               return png_safe_execute(image, png_image_read_header, image);
1523
0
            }
1524
1525
            /* Clean up: just the opened file. */
1526
0
            (void)fclose(fp);
1527
0
         }
1528
1529
0
         else
1530
0
            return png_image_error(image, strerror(errno));
1531
0
      }
1532
1533
0
      else
1534
0
         return png_image_error(image,
1535
0
             "png_image_begin_read_from_file: invalid argument");
1536
0
   }
1537
1538
0
   else if (image != NULL)
1539
0
      return png_image_error(image,
1540
0
          "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
1541
1542
0
   return 0;
1543
0
}
1544
#endif /* STDIO */
1545
1546
static void PNGCBAPI
1547
png_image_memory_read(png_structp png_ptr, png_bytep out, size_t need)
1548
0
{
1549
0
   if (png_ptr != NULL)
1550
0
   {
1551
0
      png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
1552
0
      if (image != NULL)
1553
0
      {
1554
0
         png_controlp cp = image->opaque;
1555
0
         if (cp != NULL)
1556
0
         {
1557
0
            png_const_bytep memory = cp->memory;
1558
0
            size_t size = cp->size;
1559
1560
0
            if (memory != NULL && size >= need)
1561
0
            {
1562
0
               memcpy(out, memory, need);
1563
0
               cp->memory = memory + need;
1564
0
               cp->size = size - need;
1565
0
               return;
1566
0
            }
1567
1568
0
            png_error(png_ptr, "read beyond end of data");
1569
0
         }
1570
0
      }
1571
1572
0
      png_error(png_ptr, "invalid memory read");
1573
0
   }
1574
0
}
1575
1576
int PNGAPI png_image_begin_read_from_memory(png_imagep image,
1577
    png_const_voidp memory, size_t size)
1578
0
{
1579
0
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
1580
0
   {
1581
0
      if (memory != NULL && size > 0)
1582
0
      {
1583
0
         if (png_image_read_init(image) != 0)
1584
0
         {
1585
            /* Now set the IO functions to read from the memory buffer and
1586
             * store it into io_ptr.  Again do this in-place to avoid calling a
1587
             * libpng function that requires error handling.
1588
             */
1589
0
            image->opaque->memory = png_voidcast(png_const_bytep, memory);
1590
0
            image->opaque->size = size;
1591
0
            image->opaque->png_ptr->io_ptr = image;
1592
0
            image->opaque->png_ptr->read_data_fn = png_image_memory_read;
1593
1594
0
            return png_safe_execute(image, png_image_read_header, image);
1595
0
         }
1596
0
      }
1597
1598
0
      else
1599
0
         return png_image_error(image,
1600
0
             "png_image_begin_read_from_memory: invalid argument");
1601
0
   }
1602
1603
0
   else if (image != NULL)
1604
0
      return png_image_error(image,
1605
0
          "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
1606
1607
0
   return 0;
1608
0
}
1609
1610
/* Utility function to skip chunks that are not used by the simplified image
1611
 * read functions and an appropriate macro to call it.
1612
 */
1613
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1614
static void
1615
png_image_skip_unused_chunks(png_structrp png_ptr)
1616
0
{
1617
   /* Prepare the reader to ignore all recognized chunks whose data will not
1618
    * be used, i.e., all chunks recognized by libpng except for those
1619
    * involved in basic image reading:
1620
    *
1621
    *    IHDR, PLTE, IDAT, IEND
1622
    *
1623
    * Or image data handling:
1624
    *
1625
    *    tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
1626
    *
1627
    * This provides a small performance improvement and eliminates any
1628
    * potential vulnerability to security problems in the unused chunks.
1629
    *
1630
    * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
1631
    * too.  This allows the simplified API to be compiled without iCCP support,
1632
    * however if the support is there the chunk is still checked to detect
1633
    * errors (which are unfortunately quite common.)
1634
    */
1635
0
   {
1636
0
         static const png_byte chunks_to_process[] = {
1637
0
            98,  75,  71,  68, '\0',  /* bKGD */
1638
0
            99,  72,  82,  77, '\0',  /* cHRM */
1639
0
           103,  65,  77,  65, '\0',  /* gAMA */
1640
0
#        ifdef PNG_READ_iCCP_SUPPORTED
1641
0
           105,  67,  67,  80, '\0',  /* iCCP */
1642
0
#        endif
1643
0
           115,  66,  73,  84, '\0',  /* sBIT */
1644
0
           115,  82,  71,  66, '\0',  /* sRGB */
1645
0
           };
1646
1647
       /* Ignore unknown chunks and all other chunks except for the
1648
        * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
1649
        */
1650
0
       png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
1651
0
           NULL, -1);
1652
1653
       /* But do not ignore image data handling chunks */
1654
0
       png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
1655
0
           chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
1656
0
   }
1657
0
}
1658
1659
0
#  define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
1660
#else
1661
#  define PNG_SKIP_CHUNKS(p) ((void)0)
1662
#endif /* HANDLE_AS_UNKNOWN */
1663
1664
/* The following macro gives the exact rounded answer for all values in the
1665
 * range 0..255 (it actually divides by 51.2, but the rounding still generates
1666
 * the correct numbers 0..5
1667
 */
1668
0
#define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
1669
1670
/* Utility functions to make particular color-maps */
1671
static void
1672
set_file_encoding(png_image_read_control *display)
1673
0
{
1674
0
   png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
1675
0
   if (png_gamma_significant(g) != 0)
1676
0
   {
1677
0
      if (png_gamma_not_sRGB(g) != 0)
1678
0
      {
1679
0
         display->file_encoding = P_FILE;
1680
0
         display->gamma_to_linear = png_reciprocal(g);
1681
0
      }
1682
1683
0
      else
1684
0
         display->file_encoding = P_sRGB;
1685
0
   }
1686
1687
0
   else
1688
0
      display->file_encoding = P_LINEAR8;
1689
0
}
1690
1691
static unsigned int
1692
decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
1693
0
{
1694
0
   if (encoding == P_FILE) /* double check */
1695
0
      encoding = display->file_encoding;
1696
1697
0
   if (encoding == P_NOTSET) /* must be the file encoding */
1698
0
   {
1699
0
      set_file_encoding(display);
1700
0
      encoding = display->file_encoding;
1701
0
   }
1702
1703
0
   switch (encoding)
1704
0
   {
1705
0
      case P_FILE:
1706
0
         value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
1707
0
         break;
1708
1709
0
      case P_sRGB:
1710
0
         value = png_sRGB_table[value];
1711
0
         break;
1712
1713
0
      case P_LINEAR:
1714
0
         break;
1715
1716
0
      case P_LINEAR8:
1717
0
         value *= 257;
1718
0
         break;
1719
1720
0
#ifdef __GNUC__
1721
0
      default:
1722
0
         png_error(display->image->opaque->png_ptr,
1723
0
             "unexpected encoding (internal error)");
1724
0
#endif
1725
0
   }
1726
1727
0
   return value;
1728
0
}
1729
1730
static png_uint_32
1731
png_colormap_compose(png_image_read_control *display,
1732
    png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
1733
    png_uint_32 background, int encoding)
1734
0
{
1735
   /* The file value is composed on the background, the background has the given
1736
    * encoding and so does the result, the file is encoded with P_FILE and the
1737
    * file and alpha are 8-bit values.  The (output) encoding will always be
1738
    * P_LINEAR or P_sRGB.
1739
    */
1740
0
   png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
1741
0
   png_uint_32 b = decode_gamma(display, background, encoding);
1742
1743
   /* The alpha is always an 8-bit value (it comes from the palette), the value
1744
    * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
1745
    */
1746
0
   f = f * alpha + b * (255-alpha);
1747
1748
0
   if (encoding == P_LINEAR)
1749
0
   {
1750
      /* Scale to 65535; divide by 255, approximately (in fact this is extremely
1751
       * accurate, it divides by 255.00000005937181414556, with no overflow.)
1752
       */
1753
0
      f *= 257; /* Now scaled by 65535 */
1754
0
      f += f >> 16;
1755
0
      f = (f+32768) >> 16;
1756
0
   }
1757
1758
0
   else /* P_sRGB */
1759
0
      f = PNG_sRGB_FROM_LINEAR(f);
1760
1761
0
   return f;
1762
0
}
1763
1764
/* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
1765
 * be 8-bit.
1766
 */
1767
static void
1768
png_create_colormap_entry(png_image_read_control *display,
1769
    png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
1770
    png_uint_32 alpha, int encoding)
1771
0
{
1772
0
   png_imagep image = display->image;
1773
0
   int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
1774
0
       P_LINEAR : P_sRGB;
1775
0
   int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
1776
0
       (red != green || green != blue);
1777
1778
0
   if (ip > 255)
1779
0
      png_error(image->opaque->png_ptr, "color-map index out of range");
1780
1781
   /* Update the cache with whether the file gamma is significantly different
1782
    * from sRGB.
1783
    */
1784
0
   if (encoding == P_FILE)
1785
0
   {
1786
0
      if (display->file_encoding == P_NOTSET)
1787
0
         set_file_encoding(display);
1788
1789
      /* Note that the cached value may be P_FILE too, but if it is then the
1790
       * gamma_to_linear member has been set.
1791
       */
1792
0
      encoding = display->file_encoding;
1793
0
   }
1794
1795
0
   if (encoding == P_FILE)
1796
0
   {
1797
0
      png_fixed_point g = display->gamma_to_linear;
1798
1799
0
      red = png_gamma_16bit_correct(red*257, g);
1800
0
      green = png_gamma_16bit_correct(green*257, g);
1801
0
      blue = png_gamma_16bit_correct(blue*257, g);
1802
1803
0
      if (convert_to_Y != 0 || output_encoding == P_LINEAR)
1804
0
      {
1805
0
         alpha *= 257;
1806
0
         encoding = P_LINEAR;
1807
0
      }
1808
1809
0
      else
1810
0
      {
1811
0
         red = PNG_sRGB_FROM_LINEAR(red * 255);
1812
0
         green = PNG_sRGB_FROM_LINEAR(green * 255);
1813
0
         blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1814
0
         encoding = P_sRGB;
1815
0
      }
1816
0
   }
1817
1818
0
   else if (encoding == P_LINEAR8)
1819
0
   {
1820
      /* This encoding occurs quite frequently in test cases because PngSuite
1821
       * includes a gAMA 1.0 chunk with most images.
1822
       */
1823
0
      red *= 257;
1824
0
      green *= 257;
1825
0
      blue *= 257;
1826
0
      alpha *= 257;
1827
0
      encoding = P_LINEAR;
1828
0
   }
1829
1830
0
   else if (encoding == P_sRGB &&
1831
0
       (convert_to_Y  != 0 || output_encoding == P_LINEAR))
1832
0
   {
1833
      /* The values are 8-bit sRGB values, but must be converted to 16-bit
1834
       * linear.
1835
       */
1836
0
      red = png_sRGB_table[red];
1837
0
      green = png_sRGB_table[green];
1838
0
      blue = png_sRGB_table[blue];
1839
0
      alpha *= 257;
1840
0
      encoding = P_LINEAR;
1841
0
   }
1842
1843
   /* This is set if the color isn't gray but the output is. */
1844
0
   if (encoding == P_LINEAR)
1845
0
   {
1846
0
      if (convert_to_Y != 0)
1847
0
      {
1848
         /* NOTE: these values are copied from png_do_rgb_to_gray */
1849
0
         png_uint_32 y = (png_uint_32)6968 * red  + (png_uint_32)23434 * green +
1850
0
            (png_uint_32)2366 * blue;
1851
1852
0
         if (output_encoding == P_LINEAR)
1853
0
            y = (y + 16384) >> 15;
1854
1855
0
         else
1856
0
         {
1857
            /* y is scaled by 32768, we need it scaled by 255: */
1858
0
            y = (y + 128) >> 8;
1859
0
            y *= 255;
1860
0
            y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
1861
0
            alpha = PNG_DIV257(alpha);
1862
0
            encoding = P_sRGB;
1863
0
         }
1864
1865
0
         blue = red = green = y;
1866
0
      }
1867
1868
0
      else if (output_encoding == P_sRGB)
1869
0
      {
1870
0
         red = PNG_sRGB_FROM_LINEAR(red * 255);
1871
0
         green = PNG_sRGB_FROM_LINEAR(green * 255);
1872
0
         blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1873
0
         alpha = PNG_DIV257(alpha);
1874
0
         encoding = P_sRGB;
1875
0
      }
1876
0
   }
1877
1878
0
   if (encoding != output_encoding)
1879
0
      png_error(image->opaque->png_ptr, "bad encoding (internal error)");
1880
1881
   /* Store the value. */
1882
0
   {
1883
0
#     ifdef PNG_FORMAT_AFIRST_SUPPORTED
1884
0
         int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1885
0
            (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
1886
#     else
1887
#        define afirst 0
1888
#     endif
1889
0
#     ifdef PNG_FORMAT_BGR_SUPPORTED
1890
0
         int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
1891
#     else
1892
#        define bgr 0
1893
#     endif
1894
1895
0
      if (output_encoding == P_LINEAR)
1896
0
      {
1897
0
         png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
1898
1899
0
         entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1900
1901
         /* The linear 16-bit values must be pre-multiplied by the alpha channel
1902
          * value, if less than 65535 (this is, effectively, composite on black
1903
          * if the alpha channel is removed.)
1904
          */
1905
0
         switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1906
0
         {
1907
0
            case 4:
1908
0
               entry[afirst ? 0 : 3] = (png_uint_16)alpha;
1909
               /* FALLTHROUGH */
1910
1911
0
            case 3:
1912
0
               if (alpha < 65535)
1913
0
               {
1914
0
                  if (alpha > 0)
1915
0
                  {
1916
0
                     blue = (blue * alpha + 32767U)/65535U;
1917
0
                     green = (green * alpha + 32767U)/65535U;
1918
0
                     red = (red * alpha + 32767U)/65535U;
1919
0
                  }
1920
1921
0
                  else
1922
0
                     red = green = blue = 0;
1923
0
               }
1924
0
               entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
1925
0
               entry[afirst + 1] = (png_uint_16)green;
1926
0
               entry[afirst + bgr] = (png_uint_16)red;
1927
0
               break;
1928
1929
0
            case 2:
1930
0
               entry[1 ^ afirst] = (png_uint_16)alpha;
1931
               /* FALLTHROUGH */
1932
1933
0
            case 1:
1934
0
               if (alpha < 65535)
1935
0
               {
1936
0
                  if (alpha > 0)
1937
0
                     green = (green * alpha + 32767U)/65535U;
1938
1939
0
                  else
1940
0
                     green = 0;
1941
0
               }
1942
0
               entry[afirst] = (png_uint_16)green;
1943
0
               break;
1944
1945
0
            default:
1946
0
               break;
1947
0
         }
1948
0
      }
1949
1950
0
      else /* output encoding is P_sRGB */
1951
0
      {
1952
0
         png_bytep entry = png_voidcast(png_bytep, display->colormap);
1953
1954
0
         entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1955
1956
0
         switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1957
0
         {
1958
0
            case 4:
1959
0
               entry[afirst ? 0 : 3] = (png_byte)alpha;
1960
               /* FALLTHROUGH */
1961
0
            case 3:
1962
0
               entry[afirst + (2 ^ bgr)] = (png_byte)blue;
1963
0
               entry[afirst + 1] = (png_byte)green;
1964
0
               entry[afirst + bgr] = (png_byte)red;
1965
0
               break;
1966
1967
0
            case 2:
1968
0
               entry[1 ^ afirst] = (png_byte)alpha;
1969
               /* FALLTHROUGH */
1970
0
            case 1:
1971
0
               entry[afirst] = (png_byte)green;
1972
0
               break;
1973
1974
0
            default:
1975
0
               break;
1976
0
         }
1977
0
      }
1978
1979
#     ifdef afirst
1980
#        undef afirst
1981
#     endif
1982
#     ifdef bgr
1983
#        undef bgr
1984
#     endif
1985
0
   }
1986
0
}
1987
1988
static int
1989
make_gray_file_colormap(png_image_read_control *display)
1990
0
{
1991
0
   unsigned int i;
1992
1993
0
   for (i=0; i<256; ++i)
1994
0
      png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
1995
1996
0
   return (int)i;
1997
0
}
1998
1999
static int
2000
make_gray_colormap(png_image_read_control *display)
2001
0
{
2002
0
   unsigned int i;
2003
2004
0
   for (i=0; i<256; ++i)
2005
0
      png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
2006
2007
0
   return (int)i;
2008
0
}
2009
0
#define PNG_GRAY_COLORMAP_ENTRIES 256
2010
2011
static int
2012
make_ga_colormap(png_image_read_control *display)
2013
0
{
2014
0
   unsigned int i, a;
2015
2016
   /* Alpha is retained, the output will be a color-map with entries
2017
    * selected by six levels of alpha.  One transparent entry, 6 gray
2018
    * levels for all the intermediate alpha values, leaving 230 entries
2019
    * for the opaque grays.  The color-map entries are the six values
2020
    * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
2021
    * relevant entry.
2022
    *
2023
    * if (alpha > 229) // opaque
2024
    * {
2025
    *    // The 231 entries are selected to make the math below work:
2026
    *    base = 0;
2027
    *    entry = (231 * gray + 128) >> 8;
2028
    * }
2029
    * else if (alpha < 26) // transparent
2030
    * {
2031
    *    base = 231;
2032
    *    entry = 0;
2033
    * }
2034
    * else // partially opaque
2035
    * {
2036
    *    base = 226 + 6 * PNG_DIV51(alpha);
2037
    *    entry = PNG_DIV51(gray);
2038
    * }
2039
    */
2040
0
   i = 0;
2041
0
   while (i < 231)
2042
0
   {
2043
0
      unsigned int gray = (i * 256 + 115) / 231;
2044
0
      png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
2045
0
   }
2046
2047
   /* 255 is used here for the component values for consistency with the code
2048
    * that undoes premultiplication in pngwrite.c.
2049
    */
2050
0
   png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
2051
2052
0
   for (a=1; a<5; ++a)
2053
0
   {
2054
0
      unsigned int g;
2055
2056
0
      for (g=0; g<6; ++g)
2057
0
         png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
2058
0
             P_sRGB);
2059
0
   }
2060
2061
0
   return (int)i;
2062
0
}
2063
2064
0
#define PNG_GA_COLORMAP_ENTRIES 256
2065
2066
static int
2067
make_rgb_colormap(png_image_read_control *display)
2068
0
{
2069
0
   unsigned int i, r;
2070
2071
   /* Build a 6x6x6 opaque RGB cube */
2072
0
   for (i=r=0; r<6; ++r)
2073
0
   {
2074
0
      unsigned int g;
2075
2076
0
      for (g=0; g<6; ++g)
2077
0
      {
2078
0
         unsigned int b;
2079
2080
0
         for (b=0; b<6; ++b)
2081
0
            png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
2082
0
                P_sRGB);
2083
0
      }
2084
0
   }
2085
2086
0
   return (int)i;
2087
0
}
2088
2089
0
#define PNG_RGB_COLORMAP_ENTRIES 216
2090
2091
/* Return a palette index to the above palette given three 8-bit sRGB values. */
2092
#define PNG_RGB_INDEX(r,g,b) \
2093
0
   ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
2094
2095
static int
2096
png_image_read_colormap(png_voidp argument)
2097
0
{
2098
0
   png_image_read_control *display =
2099
0
      png_voidcast(png_image_read_control*, argument);
2100
0
   png_imagep image = display->image;
2101
2102
0
   png_structrp png_ptr = image->opaque->png_ptr;
2103
0
   png_uint_32 output_format = image->format;
2104
0
   int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2105
0
      P_LINEAR : P_sRGB;
2106
2107
0
   unsigned int cmap_entries;
2108
0
   unsigned int output_processing;        /* Output processing option */
2109
0
   unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
2110
2111
   /* Background information; the background color and the index of this color
2112
    * in the color-map if it exists (else 256).
2113
    */
2114
0
   unsigned int background_index = 256;
2115
0
   png_uint_32 back_r, back_g, back_b;
2116
2117
   /* Flags to accumulate things that need to be done to the input. */
2118
0
   int expand_tRNS = 0;
2119
2120
   /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
2121
    * very difficult to do, the results look awful, and it is difficult to see
2122
    * what possible use it is because the application can't control the
2123
    * color-map.
2124
    */
2125
0
   if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
2126
0
         png_ptr->num_trans > 0) /* alpha in input */ &&
2127
0
      ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
2128
0
   {
2129
0
      if (output_encoding == P_LINEAR) /* compose on black */
2130
0
         back_b = back_g = back_r = 0;
2131
2132
0
      else if (display->background == NULL /* no way to remove it */)
2133
0
         png_error(png_ptr,
2134
0
             "background color must be supplied to remove alpha/transparency");
2135
2136
      /* Get a copy of the background color (this avoids repeating the checks
2137
       * below.)  The encoding is 8-bit sRGB or 16-bit linear, depending on the
2138
       * output format.
2139
       */
2140
0
      else
2141
0
      {
2142
0
         back_g = display->background->green;
2143
0
         if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
2144
0
         {
2145
0
            back_r = display->background->red;
2146
0
            back_b = display->background->blue;
2147
0
         }
2148
0
         else
2149
0
            back_b = back_r = back_g;
2150
0
      }
2151
0
   }
2152
2153
0
   else if (output_encoding == P_LINEAR)
2154
0
      back_b = back_r = back_g = 65535;
2155
2156
0
   else
2157
0
      back_b = back_r = back_g = 255;
2158
2159
   /* Default the input file gamma if required - this is necessary because
2160
    * libpng assumes that if no gamma information is present the data is in the
2161
    * output format, but the simplified API deduces the gamma from the input
2162
    * format.
2163
    */
2164
0
   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
2165
0
   {
2166
      /* Do this directly, not using the png_colorspace functions, to ensure
2167
       * that it happens even if the colorspace is invalid (though probably if
2168
       * it is the setting will be ignored)  Note that the same thing can be
2169
       * achieved at the application interface with png_set_gAMA.
2170
       */
2171
0
      if (png_ptr->bit_depth == 16 &&
2172
0
         (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
2173
0
         png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
2174
2175
0
      else
2176
0
         png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
2177
2178
0
      png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
2179
0
   }
2180
2181
   /* Decide what to do based on the PNG color type of the input data.  The
2182
    * utility function png_create_colormap_entry deals with most aspects of the
2183
    * output transformations; this code works out how to produce bytes of
2184
    * color-map entries from the original format.
2185
    */
2186
0
   switch (png_ptr->color_type)
2187
0
   {
2188
0
      case PNG_COLOR_TYPE_GRAY:
2189
0
         if (png_ptr->bit_depth <= 8)
2190
0
         {
2191
            /* There at most 256 colors in the output, regardless of
2192
             * transparency.
2193
             */
2194
0
            unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
2195
2196
0
            cmap_entries = 1U << png_ptr->bit_depth;
2197
0
            if (cmap_entries > image->colormap_entries)
2198
0
               png_error(png_ptr, "gray[8] color-map: too few entries");
2199
2200
0
            step = 255 / (cmap_entries - 1);
2201
0
            output_processing = PNG_CMAP_NONE;
2202
2203
            /* If there is a tRNS chunk then this either selects a transparent
2204
             * value or, if the output has no alpha, the background color.
2205
             */
2206
0
            if (png_ptr->num_trans > 0)
2207
0
            {
2208
0
               trans = png_ptr->trans_color.gray;
2209
2210
0
               if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
2211
0
                  back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2212
0
            }
2213
2214
            /* png_create_colormap_entry just takes an RGBA and writes the
2215
             * corresponding color-map entry using the format from 'image',
2216
             * including the required conversion to sRGB or linear as
2217
             * appropriate.  The input values are always either sRGB (if the
2218
             * gamma correction flag is 0) or 0..255 scaled file encoded values
2219
             * (if the function must gamma correct them).
2220
             */
2221
0
            for (i=val=0; i<cmap_entries; ++i, val += step)
2222
0
            {
2223
               /* 'i' is a file value.  While this will result in duplicated
2224
                * entries for 8-bit non-sRGB encoded files it is necessary to
2225
                * have non-gamma corrected values to do tRNS handling.
2226
                */
2227
0
               if (i != trans)
2228
0
                  png_create_colormap_entry(display, i, val, val, val, 255,
2229
0
                      P_FILE/*8-bit with file gamma*/);
2230
2231
               /* Else this entry is transparent.  The colors don't matter if
2232
                * there is an alpha channel (back_alpha == 0), but it does no
2233
                * harm to pass them in; the values are not set above so this
2234
                * passes in white.
2235
                *
2236
                * NOTE: this preserves the full precision of the application
2237
                * supplied background color when it is used.
2238
                */
2239
0
               else
2240
0
                  png_create_colormap_entry(display, i, back_r, back_g, back_b,
2241
0
                      back_alpha, output_encoding);
2242
0
            }
2243
2244
            /* We need libpng to preserve the original encoding. */
2245
0
            data_encoding = P_FILE;
2246
2247
            /* The rows from libpng, while technically gray values, are now also
2248
             * color-map indices; however, they may need to be expanded to 1
2249
             * byte per pixel.  This is what png_set_packing does (i.e., it
2250
             * unpacks the bit values into bytes.)
2251
             */
2252
0
            if (png_ptr->bit_depth < 8)
2253
0
               png_set_packing(png_ptr);
2254
0
         }
2255
2256
0
         else /* bit depth is 16 */
2257
0
         {
2258
            /* The 16-bit input values can be converted directly to 8-bit gamma
2259
             * encoded values; however, if a tRNS chunk is present 257 color-map
2260
             * entries are required.  This means that the extra entry requires
2261
             * special processing; add an alpha channel, sacrifice gray level
2262
             * 254 and convert transparent (alpha==0) entries to that.
2263
             *
2264
             * Use libpng to chop the data to 8 bits.  Convert it to sRGB at the
2265
             * same time to minimize quality loss.  If a tRNS chunk is present
2266
             * this means libpng must handle it too; otherwise it is impossible
2267
             * to do the exact match on the 16-bit value.
2268
             *
2269
             * If the output has no alpha channel *and* the background color is
2270
             * gray then it is possible to let libpng handle the substitution by
2271
             * ensuring that the corresponding gray level matches the background
2272
             * color exactly.
2273
             */
2274
0
            data_encoding = P_sRGB;
2275
2276
0
            if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2277
0
               png_error(png_ptr, "gray[16] color-map: too few entries");
2278
2279
0
            cmap_entries = (unsigned int)make_gray_colormap(display);
2280
2281
0
            if (png_ptr->num_trans > 0)
2282
0
            {
2283
0
               unsigned int back_alpha;
2284
2285
0
               if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2286
0
                  back_alpha = 0;
2287
2288
0
               else
2289
0
               {
2290
0
                  if (back_r == back_g && back_g == back_b)
2291
0
                  {
2292
                     /* Background is gray; no special processing will be
2293
                      * required.
2294
                      */
2295
0
                     png_color_16 c;
2296
0
                     png_uint_32 gray = back_g;
2297
2298
0
                     if (output_encoding == P_LINEAR)
2299
0
                     {
2300
0
                        gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2301
2302
                        /* And make sure the corresponding palette entry
2303
                         * matches.
2304
                         */
2305
0
                        png_create_colormap_entry(display, gray, back_g, back_g,
2306
0
                            back_g, 65535, P_LINEAR);
2307
0
                     }
2308
2309
                     /* The background passed to libpng, however, must be the
2310
                      * sRGB value.
2311
                      */
2312
0
                     c.index = 0; /*unused*/
2313
0
                     c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2314
2315
                     /* NOTE: does this work without expanding tRNS to alpha?
2316
                      * It should be the color->gray case below apparently
2317
                      * doesn't.
2318
                      */
2319
0
                     png_set_background_fixed(png_ptr, &c,
2320
0
                         PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2321
0
                         0/*gamma: not used*/);
2322
2323
0
                     output_processing = PNG_CMAP_NONE;
2324
0
                     break;
2325
0
                  }
2326
#ifdef __COVERITY__
2327
                 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
2328
                  * here.
2329
                  */
2330
                  back_alpha = 255;
2331
#else
2332
0
                  back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2333
0
#endif
2334
0
               }
2335
2336
               /* output_processing means that the libpng-processed row will be
2337
                * 8-bit GA and it has to be processing to single byte color-map
2338
                * values.  Entry 254 is replaced by either a completely
2339
                * transparent entry or by the background color at full
2340
                * precision (and the background color is not a simple gray
2341
                * level in this case.)
2342
                */
2343
0
               expand_tRNS = 1;
2344
0
               output_processing = PNG_CMAP_TRANS;
2345
0
               background_index = 254;
2346
2347
               /* And set (overwrite) color-map entry 254 to the actual
2348
                * background color at full precision.
2349
                */
2350
0
               png_create_colormap_entry(display, 254, back_r, back_g, back_b,
2351
0
                   back_alpha, output_encoding);
2352
0
            }
2353
2354
0
            else
2355
0
               output_processing = PNG_CMAP_NONE;
2356
0
         }
2357
0
         break;
2358
2359
0
      case PNG_COLOR_TYPE_GRAY_ALPHA:
2360
         /* 8-bit or 16-bit PNG with two channels - gray and alpha.  A minimum
2361
          * of 65536 combinations.  If, however, the alpha channel is to be
2362
          * removed there are only 256 possibilities if the background is gray.
2363
          * (Otherwise there is a subset of the 65536 possibilities defined by
2364
          * the triangle between black, white and the background color.)
2365
          *
2366
          * Reduce 16-bit files to 8-bit and sRGB encode the result.  No need to
2367
          * worry about tRNS matching - tRNS is ignored if there is an alpha
2368
          * channel.
2369
          */
2370
0
         data_encoding = P_sRGB;
2371
2372
0
         if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2373
0
         {
2374
0
            if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2375
0
               png_error(png_ptr, "gray+alpha color-map: too few entries");
2376
2377
0
            cmap_entries = (unsigned int)make_ga_colormap(display);
2378
2379
0
            background_index = PNG_CMAP_GA_BACKGROUND;
2380
0
            output_processing = PNG_CMAP_GA;
2381
0
         }
2382
2383
0
         else /* alpha is removed */
2384
0
         {
2385
            /* Alpha must be removed as the PNG data is processed when the
2386
             * background is a color because the G and A channels are
2387
             * independent and the vector addition (non-parallel vectors) is a
2388
             * 2-D problem.
2389
             *
2390
             * This can be reduced to the same algorithm as above by making a
2391
             * colormap containing gray levels (for the opaque grays), a
2392
             * background entry (for a transparent pixel) and a set of four six
2393
             * level color values, one set for each intermediate alpha value.
2394
             * See the comments in make_ga_colormap for how this works in the
2395
             * per-pixel processing.
2396
             *
2397
             * If the background is gray, however, we only need a 256 entry gray
2398
             * level color map.  It is sufficient to make the entry generated
2399
             * for the background color be exactly the color specified.
2400
             */
2401
0
            if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
2402
0
               (back_r == back_g && back_g == back_b))
2403
0
            {
2404
               /* Background is gray; no special processing will be required. */
2405
0
               png_color_16 c;
2406
0
               png_uint_32 gray = back_g;
2407
2408
0
               if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2409
0
                  png_error(png_ptr, "gray-alpha color-map: too few entries");
2410
2411
0
               cmap_entries = (unsigned int)make_gray_colormap(display);
2412
2413
0
               if (output_encoding == P_LINEAR)
2414
0
               {
2415
0
                  gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2416
2417
                  /* And make sure the corresponding palette entry matches. */
2418
0
                  png_create_colormap_entry(display, gray, back_g, back_g,
2419
0
                      back_g, 65535, P_LINEAR);
2420
0
               }
2421
2422
               /* The background passed to libpng, however, must be the sRGB
2423
                * value.
2424
                */
2425
0
               c.index = 0; /*unused*/
2426
0
               c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2427
2428
0
               png_set_background_fixed(png_ptr, &c,
2429
0
                   PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2430
0
                   0/*gamma: not used*/);
2431
2432
0
               output_processing = PNG_CMAP_NONE;
2433
0
            }
2434
2435
0
            else
2436
0
            {
2437
0
               png_uint_32 i, a;
2438
2439
               /* This is the same as png_make_ga_colormap, above, except that
2440
                * the entries are all opaque.
2441
                */
2442
0
               if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2443
0
                  png_error(png_ptr, "ga-alpha color-map: too few entries");
2444
2445
0
               i = 0;
2446
0
               while (i < 231)
2447
0
               {
2448
0
                  png_uint_32 gray = (i * 256 + 115) / 231;
2449
0
                  png_create_colormap_entry(display, i++, gray, gray, gray,
2450
0
                      255, P_sRGB);
2451
0
               }
2452
2453
               /* NOTE: this preserves the full precision of the application
2454
                * background color.
2455
                */
2456
0
               background_index = i;
2457
0
               png_create_colormap_entry(display, i++, back_r, back_g, back_b,
2458
#ifdef __COVERITY__
2459
                   /* Coverity claims that output_encoding
2460
                    * cannot be 2 (P_LINEAR) here.
2461
                    */ 255U,
2462
#else
2463
0
                    output_encoding == P_LINEAR ? 65535U : 255U,
2464
0
#endif
2465
0
                    output_encoding);
2466
2467
               /* For non-opaque input composite on the sRGB background - this
2468
                * requires inverting the encoding for each component.  The input
2469
                * is still converted to the sRGB encoding because this is a
2470
                * reasonable approximate to the logarithmic curve of human
2471
                * visual sensitivity, at least over the narrow range which PNG
2472
                * represents.  Consequently 'G' is always sRGB encoded, while
2473
                * 'A' is linear.  We need the linear background colors.
2474
                */
2475
0
               if (output_encoding == P_sRGB) /* else already linear */
2476
0
               {
2477
                  /* This may produce a value not exactly matching the
2478
                   * background, but that's ok because these numbers are only
2479
                   * used when alpha != 0
2480
                   */
2481
0
                  back_r = png_sRGB_table[back_r];
2482
0
                  back_g = png_sRGB_table[back_g];
2483
0
                  back_b = png_sRGB_table[back_b];
2484
0
               }
2485
2486
0
               for (a=1; a<5; ++a)
2487
0
               {
2488
0
                  unsigned int g;
2489
2490
                  /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
2491
                   * by an 8-bit alpha value (0..255).
2492
                   */
2493
0
                  png_uint_32 alpha = 51 * a;
2494
0
                  png_uint_32 back_rx = (255-alpha) * back_r;
2495
0
                  png_uint_32 back_gx = (255-alpha) * back_g;
2496
0
                  png_uint_32 back_bx = (255-alpha) * back_b;
2497
2498
0
                  for (g=0; g<6; ++g)
2499
0
                  {
2500
0
                     png_uint_32 gray = png_sRGB_table[g*51] * alpha;
2501
2502
0
                     png_create_colormap_entry(display, i++,
2503
0
                         PNG_sRGB_FROM_LINEAR(gray + back_rx),
2504
0
                         PNG_sRGB_FROM_LINEAR(gray + back_gx),
2505
0
                         PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
2506
0
                  }
2507
0
               }
2508
2509
0
               cmap_entries = i;
2510
0
               output_processing = PNG_CMAP_GA;
2511
0
            }
2512
0
         }
2513
0
         break;
2514
2515
0
      case PNG_COLOR_TYPE_RGB:
2516
0
      case PNG_COLOR_TYPE_RGB_ALPHA:
2517
         /* Exclude the case where the output is gray; we can always handle this
2518
          * with the cases above.
2519
          */
2520
0
         if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
2521
0
         {
2522
            /* The color-map will be grayscale, so we may as well convert the
2523
             * input RGB values to a simple grayscale and use the grayscale
2524
             * code above.
2525
             *
2526
             * NOTE: calling this apparently damages the recognition of the
2527
             * transparent color in background color handling; call
2528
             * png_set_tRNS_to_alpha before png_set_background_fixed.
2529
             */
2530
0
            png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
2531
0
                -1);
2532
0
            data_encoding = P_sRGB;
2533
2534
            /* The output will now be one or two 8-bit gray or gray+alpha
2535
             * channels.  The more complex case arises when the input has alpha.
2536
             */
2537
0
            if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2538
0
               png_ptr->num_trans > 0) &&
2539
0
               (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2540
0
            {
2541
               /* Both input and output have an alpha channel, so no background
2542
                * processing is required; just map the GA bytes to the right
2543
                * color-map entry.
2544
                */
2545
0
               expand_tRNS = 1;
2546
2547
0
               if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2548
0
                  png_error(png_ptr, "rgb[ga] color-map: too few entries");
2549
2550
0
               cmap_entries = (unsigned int)make_ga_colormap(display);
2551
0
               background_index = PNG_CMAP_GA_BACKGROUND;
2552
0
               output_processing = PNG_CMAP_GA;
2553
0
            }
2554
2555
0
            else
2556
0
            {
2557
               /* Either the input or the output has no alpha channel, so there
2558
                * will be no non-opaque pixels in the color-map; it will just be
2559
                * grayscale.
2560
                */
2561
0
               if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2562
0
                  png_error(png_ptr, "rgb[gray] color-map: too few entries");
2563
2564
               /* Ideally this code would use libpng to do the gamma correction,
2565
                * but if an input alpha channel is to be removed we will hit the
2566
                * libpng bug in gamma+compose+rgb-to-gray (the double gamma
2567
                * correction bug).  Fix this by dropping the gamma correction in
2568
                * this case and doing it in the palette; this will result in
2569
                * duplicate palette entries, but that's better than the
2570
                * alternative of double gamma correction.
2571
                */
2572
0
               if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2573
0
                  png_ptr->num_trans > 0) &&
2574
0
                  png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
2575
0
               {
2576
0
                  cmap_entries = (unsigned int)make_gray_file_colormap(display);
2577
0
                  data_encoding = P_FILE;
2578
0
               }
2579
2580
0
               else
2581
0
                  cmap_entries = (unsigned int)make_gray_colormap(display);
2582
2583
               /* But if the input has alpha or transparency it must be removed
2584
                */
2585
0
               if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2586
0
                  png_ptr->num_trans > 0)
2587
0
               {
2588
0
                  png_color_16 c;
2589
0
                  png_uint_32 gray = back_g;
2590
2591
                  /* We need to ensure that the application background exists in
2592
                   * the colormap and that completely transparent pixels map to
2593
                   * it.  Achieve this simply by ensuring that the entry
2594
                   * selected for the background really is the background color.
2595
                   */
2596
0
                  if (data_encoding == P_FILE) /* from the fixup above */
2597
0
                  {
2598
                     /* The app supplied a gray which is in output_encoding, we
2599
                      * need to convert it to a value of the input (P_FILE)
2600
                      * encoding then set this palette entry to the required
2601
                      * output encoding.
2602
                      */
2603
0
                     if (output_encoding == P_sRGB)
2604
0
                        gray = png_sRGB_table[gray]; /* now P_LINEAR */
2605
2606
0
                     gray = PNG_DIV257(png_gamma_16bit_correct(gray,
2607
0
                         png_ptr->colorspace.gamma)); /* now P_FILE */
2608
2609
                     /* And make sure the corresponding palette entry contains
2610
                      * exactly the required sRGB value.
2611
                      */
2612
0
                     png_create_colormap_entry(display, gray, back_g, back_g,
2613
0
                         back_g, 0/*unused*/, output_encoding);
2614
0
                  }
2615
2616
0
                  else if (output_encoding == P_LINEAR)
2617
0
                  {
2618
0
                     gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2619
2620
                     /* And make sure the corresponding palette entry matches.
2621
                      */
2622
0
                     png_create_colormap_entry(display, gray, back_g, back_g,
2623
0
                        back_g, 0/*unused*/, P_LINEAR);
2624
0
                  }
2625
2626
                  /* The background passed to libpng, however, must be the
2627
                   * output (normally sRGB) value.
2628
                   */
2629
0
                  c.index = 0; /*unused*/
2630
0
                  c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2631
2632
                  /* NOTE: the following is apparently a bug in libpng. Without
2633
                   * it the transparent color recognition in
2634
                   * png_set_background_fixed seems to go wrong.
2635
                   */
2636
0
                  expand_tRNS = 1;
2637
0
                  png_set_background_fixed(png_ptr, &c,
2638
0
                      PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2639
0
                      0/*gamma: not used*/);
2640
0
               }
2641
2642
0
               output_processing = PNG_CMAP_NONE;
2643
0
            }
2644
0
         }
2645
2646
0
         else /* output is color */
2647
0
         {
2648
            /* We could use png_quantize here so long as there is no transparent
2649
             * color or alpha; png_quantize ignores alpha.  Easier overall just
2650
             * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
2651
             * Consequently we always want libpng to produce sRGB data.
2652
             */
2653
0
            data_encoding = P_sRGB;
2654
2655
            /* Is there any transparency or alpha? */
2656
0
            if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2657
0
               png_ptr->num_trans > 0)
2658
0
            {
2659
               /* Is there alpha in the output too?  If so all four channels are
2660
                * processed into a special RGB cube with alpha support.
2661
                */
2662
0
               if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2663
0
               {
2664
0
                  png_uint_32 r;
2665
2666
0
                  if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2667
0
                     png_error(png_ptr, "rgb+alpha color-map: too few entries");
2668
2669
0
                  cmap_entries = (unsigned int)make_rgb_colormap(display);
2670
2671
                  /* Add a transparent entry. */
2672
0
                  png_create_colormap_entry(display, cmap_entries, 255, 255,
2673
0
                      255, 0, P_sRGB);
2674
2675
                  /* This is stored as the background index for the processing
2676
                   * algorithm.
2677
                   */
2678
0
                  background_index = cmap_entries++;
2679
2680
                  /* Add 27 r,g,b entries each with alpha 0.5. */
2681
0
                  for (r=0; r<256; r = (r << 1) | 0x7f)
2682
0
                  {
2683
0
                     png_uint_32 g;
2684
2685
0
                     for (g=0; g<256; g = (g << 1) | 0x7f)
2686
0
                     {
2687
0
                        png_uint_32 b;
2688
2689
                        /* This generates components with the values 0, 127 and
2690
                         * 255
2691
                         */
2692
0
                        for (b=0; b<256; b = (b << 1) | 0x7f)
2693
0
                           png_create_colormap_entry(display, cmap_entries++,
2694
0
                               r, g, b, 128, P_sRGB);
2695
0
                     }
2696
0
                  }
2697
2698
0
                  expand_tRNS = 1;
2699
0
                  output_processing = PNG_CMAP_RGB_ALPHA;
2700
0
               }
2701
2702
0
               else
2703
0
               {
2704
                  /* Alpha/transparency must be removed.  The background must
2705
                   * exist in the color map (achieved by setting adding it after
2706
                   * the 666 color-map).  If the standard processing code will
2707
                   * pick up this entry automatically that's all that is
2708
                   * required; libpng can be called to do the background
2709
                   * processing.
2710
                   */
2711
0
                  unsigned int sample_size =
2712
0
                     PNG_IMAGE_SAMPLE_SIZE(output_format);
2713
0
                  png_uint_32 r, g, b; /* sRGB background */
2714
2715
0
                  if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2716
0
                     png_error(png_ptr, "rgb-alpha color-map: too few entries");
2717
2718
0
                  cmap_entries = (unsigned int)make_rgb_colormap(display);
2719
2720
0
                  png_create_colormap_entry(display, cmap_entries, back_r,
2721
0
                      back_g, back_b, 0/*unused*/, output_encoding);
2722
2723
0
                  if (output_encoding == P_LINEAR)
2724
0
                  {
2725
0
                     r = PNG_sRGB_FROM_LINEAR(back_r * 255);
2726
0
                     g = PNG_sRGB_FROM_LINEAR(back_g * 255);
2727
0
                     b = PNG_sRGB_FROM_LINEAR(back_b * 255);
2728
0
                  }
2729
2730
0
                  else
2731
0
                  {
2732
0
                     r = back_r;
2733
0
                     g = back_g;
2734
0
                     b = back_g;
2735
0
                  }
2736
2737
                  /* Compare the newly-created color-map entry with the one the
2738
                   * PNG_CMAP_RGB algorithm will use.  If the two entries don't
2739
                   * match, add the new one and set this as the background
2740
                   * index.
2741
                   */
2742
0
                  if (memcmp((png_const_bytep)display->colormap +
2743
0
                      sample_size * cmap_entries,
2744
0
                      (png_const_bytep)display->colormap +
2745
0
                          sample_size * PNG_RGB_INDEX(r,g,b),
2746
0
                     sample_size) != 0)
2747
0
                  {
2748
                     /* The background color must be added. */
2749
0
                     background_index = cmap_entries++;
2750
2751
                     /* Add 27 r,g,b entries each with created by composing with
2752
                      * the background at alpha 0.5.
2753
                      */
2754
0
                     for (r=0; r<256; r = (r << 1) | 0x7f)
2755
0
                     {
2756
0
                        for (g=0; g<256; g = (g << 1) | 0x7f)
2757
0
                        {
2758
                           /* This generates components with the values 0, 127
2759
                            * and 255
2760
                            */
2761
0
                           for (b=0; b<256; b = (b << 1) | 0x7f)
2762
0
                              png_create_colormap_entry(display, cmap_entries++,
2763
0
                                  png_colormap_compose(display, r, P_sRGB, 128,
2764
0
                                      back_r, output_encoding),
2765
0
                                  png_colormap_compose(display, g, P_sRGB, 128,
2766
0
                                      back_g, output_encoding),
2767
0
                                  png_colormap_compose(display, b, P_sRGB, 128,
2768
0
                                      back_b, output_encoding),
2769
0
                                  0/*unused*/, output_encoding);
2770
0
                        }
2771
0
                     }
2772
2773
0
                     expand_tRNS = 1;
2774
0
                     output_processing = PNG_CMAP_RGB_ALPHA;
2775
0
                  }
2776
2777
0
                  else /* background color is in the standard color-map */
2778
0
                  {
2779
0
                     png_color_16 c;
2780
2781
0
                     c.index = 0; /*unused*/
2782
0
                     c.red = (png_uint_16)back_r;
2783
0
                     c.gray = c.green = (png_uint_16)back_g;
2784
0
                     c.blue = (png_uint_16)back_b;
2785
2786
0
                     png_set_background_fixed(png_ptr, &c,
2787
0
                         PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2788
0
                         0/*gamma: not used*/);
2789
2790
0
                     output_processing = PNG_CMAP_RGB;
2791
0
                  }
2792
0
               }
2793
0
            }
2794
2795
0
            else /* no alpha or transparency in the input */
2796
0
            {
2797
               /* Alpha in the output is irrelevant, simply map the opaque input
2798
                * pixels to the 6x6x6 color-map.
2799
                */
2800
0
               if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
2801
0
                  png_error(png_ptr, "rgb color-map: too few entries");
2802
2803
0
               cmap_entries = (unsigned int)make_rgb_colormap(display);
2804
0
               output_processing = PNG_CMAP_RGB;
2805
0
            }
2806
0
         }
2807
0
         break;
2808
2809
0
      case PNG_COLOR_TYPE_PALETTE:
2810
         /* It's already got a color-map.  It may be necessary to eliminate the
2811
          * tRNS entries though.
2812
          */
2813
0
         {
2814
0
            unsigned int num_trans = png_ptr->num_trans;
2815
0
            png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
2816
0
            png_const_colorp colormap = png_ptr->palette;
2817
0
            int do_background = trans != NULL &&
2818
0
               (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
2819
0
            unsigned int i;
2820
2821
            /* Just in case: */
2822
0
            if (trans == NULL)
2823
0
               num_trans = 0;
2824
2825
0
            output_processing = PNG_CMAP_NONE;
2826
0
            data_encoding = P_FILE; /* Don't change from color-map indices */
2827
0
            cmap_entries = (unsigned int)png_ptr->num_palette;
2828
0
            if (cmap_entries > 256)
2829
0
               cmap_entries = 256;
2830
2831
0
            if (cmap_entries > (unsigned int)image->colormap_entries)
2832
0
               png_error(png_ptr, "palette color-map: too few entries");
2833
2834
0
            for (i=0; i < cmap_entries; ++i)
2835
0
            {
2836
0
               if (do_background != 0 && i < num_trans && trans[i] < 255)
2837
0
               {
2838
0
                  if (trans[i] == 0)
2839
0
                     png_create_colormap_entry(display, i, back_r, back_g,
2840
0
                         back_b, 0, output_encoding);
2841
2842
0
                  else
2843
0
                  {
2844
                     /* Must compose the PNG file color in the color-map entry
2845
                      * on the sRGB color in 'back'.
2846
                      */
2847
0
                     png_create_colormap_entry(display, i,
2848
0
                         png_colormap_compose(display, colormap[i].red,
2849
0
                             P_FILE, trans[i], back_r, output_encoding),
2850
0
                         png_colormap_compose(display, colormap[i].green,
2851
0
                             P_FILE, trans[i], back_g, output_encoding),
2852
0
                         png_colormap_compose(display, colormap[i].blue,
2853
0
                             P_FILE, trans[i], back_b, output_encoding),
2854
0
                         output_encoding == P_LINEAR ? trans[i] * 257U :
2855
0
                             trans[i],
2856
0
                         output_encoding);
2857
0
                  }
2858
0
               }
2859
2860
0
               else
2861
0
                  png_create_colormap_entry(display, i, colormap[i].red,
2862
0
                      colormap[i].green, colormap[i].blue,
2863
0
                      i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
2864
0
            }
2865
2866
            /* The PNG data may have indices packed in fewer than 8 bits, it
2867
             * must be expanded if so.
2868
             */
2869
0
            if (png_ptr->bit_depth < 8)
2870
0
               png_set_packing(png_ptr);
2871
0
         }
2872
0
         break;
2873
2874
0
      default:
2875
0
         png_error(png_ptr, "invalid PNG color type");
2876
         /*NOT REACHED*/
2877
0
   }
2878
2879
   /* Now deal with the output processing */
2880
0
   if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
2881
0
       (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
2882
0
      png_set_tRNS_to_alpha(png_ptr);
2883
2884
0
   switch (data_encoding)
2885
0
   {
2886
0
      case P_sRGB:
2887
         /* Change to 8-bit sRGB */
2888
0
         png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
2889
         /* FALLTHROUGH */
2890
2891
0
      case P_FILE:
2892
0
         if (png_ptr->bit_depth > 8)
2893
0
            png_set_scale_16(png_ptr);
2894
0
         break;
2895
2896
0
#ifdef __GNUC__
2897
0
      default:
2898
0
         png_error(png_ptr, "bad data option (internal error)");
2899
0
#endif
2900
0
   }
2901
2902
0
   if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
2903
0
      png_error(png_ptr, "color map overflow (BAD internal error)");
2904
2905
0
   image->colormap_entries = cmap_entries;
2906
2907
   /* Double check using the recorded background index */
2908
0
   switch (output_processing)
2909
0
   {
2910
0
      case PNG_CMAP_NONE:
2911
0
         if (background_index != PNG_CMAP_NONE_BACKGROUND)
2912
0
            goto bad_background;
2913
0
         break;
2914
2915
0
      case PNG_CMAP_GA:
2916
0
         if (background_index != PNG_CMAP_GA_BACKGROUND)
2917
0
            goto bad_background;
2918
0
         break;
2919
2920
0
      case PNG_CMAP_TRANS:
2921
0
         if (background_index >= cmap_entries ||
2922
0
            background_index != PNG_CMAP_TRANS_BACKGROUND)
2923
0
            goto bad_background;
2924
0
         break;
2925
2926
0
      case PNG_CMAP_RGB:
2927
0
         if (background_index != PNG_CMAP_RGB_BACKGROUND)
2928
0
            goto bad_background;
2929
0
         break;
2930
2931
0
      case PNG_CMAP_RGB_ALPHA:
2932
0
         if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
2933
0
            goto bad_background;
2934
0
         break;
2935
2936
0
      default:
2937
0
         png_error(png_ptr, "bad processing option (internal error)");
2938
2939
0
      bad_background:
2940
0
         png_error(png_ptr, "bad background index (internal error)");
2941
0
   }
2942
2943
0
   display->colormap_processing = (int)output_processing;
2944
2945
0
   return 1/*ok*/;
2946
0
}
2947
2948
/* The final part of the color-map read called from png_image_finish_read. */
2949
static int
2950
png_image_read_and_map(png_voidp argument)
2951
0
{
2952
0
   png_image_read_control *display = png_voidcast(png_image_read_control*,
2953
0
       argument);
2954
0
   png_imagep image = display->image;
2955
0
   png_structrp png_ptr = image->opaque->png_ptr;
2956
0
   int passes;
2957
2958
   /* Called when the libpng data must be transformed into the color-mapped
2959
    * form.  There is a local row buffer in display->local and this routine must
2960
    * do the interlace handling.
2961
    */
2962
0
   switch (png_ptr->interlaced)
2963
0
   {
2964
0
      case PNG_INTERLACE_NONE:
2965
0
         passes = 1;
2966
0
         break;
2967
2968
0
      case PNG_INTERLACE_ADAM7:
2969
0
         passes = PNG_INTERLACE_ADAM7_PASSES;
2970
0
         break;
2971
2972
0
      default:
2973
0
         png_error(png_ptr, "unknown interlace type");
2974
0
   }
2975
2976
0
   {
2977
0
      png_uint_32  height = image->height;
2978
0
      png_uint_32  width = image->width;
2979
0
      int          proc = display->colormap_processing;
2980
0
      png_bytep    first_row = png_voidcast(png_bytep, display->first_row);
2981
0
      ptrdiff_t    step_row = display->row_bytes;
2982
0
      int pass;
2983
2984
0
      for (pass = 0; pass < passes; ++pass)
2985
0
      {
2986
0
         unsigned int     startx, stepx, stepy;
2987
0
         png_uint_32      y;
2988
2989
0
         if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
2990
0
         {
2991
            /* The row may be empty for a short image: */
2992
0
            if (PNG_PASS_COLS(width, pass) == 0)
2993
0
               continue;
2994
2995
0
            startx = PNG_PASS_START_COL(pass);
2996
0
            stepx = PNG_PASS_COL_OFFSET(pass);
2997
0
            y = PNG_PASS_START_ROW(pass);
2998
0
            stepy = PNG_PASS_ROW_OFFSET(pass);
2999
0
         }
3000
3001
0
         else
3002
0
         {
3003
0
            y = 0;
3004
0
            startx = 0;
3005
0
            stepx = stepy = 1;
3006
0
         }
3007
3008
0
         for (; y<height; y += stepy)
3009
0
         {
3010
0
            png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3011
0
            png_bytep outrow = first_row + y * step_row;
3012
0
            png_const_bytep end_row = outrow + width;
3013
3014
            /* Read read the libpng data into the temporary buffer. */
3015
0
            png_read_row(png_ptr, inrow, NULL);
3016
3017
            /* Now process the row according to the processing option, note
3018
             * that the caller verifies that the format of the libpng output
3019
             * data is as required.
3020
             */
3021
0
            outrow += startx;
3022
0
            switch (proc)
3023
0
            {
3024
0
               case PNG_CMAP_GA:
3025
0
                  for (; outrow < end_row; outrow += stepx)
3026
0
                  {
3027
                     /* The data is always in the PNG order */
3028
0
                     unsigned int gray = *inrow++;
3029
0
                     unsigned int alpha = *inrow++;
3030
0
                     unsigned int entry;
3031
3032
                     /* NOTE: this code is copied as a comment in
3033
                      * make_ga_colormap above.  Please update the
3034
                      * comment if you change this code!
3035
                      */
3036
0
                     if (alpha > 229) /* opaque */
3037
0
                     {
3038
0
                        entry = (231 * gray + 128) >> 8;
3039
0
                     }
3040
0
                     else if (alpha < 26) /* transparent */
3041
0
                     {
3042
0
                        entry = 231;
3043
0
                     }
3044
0
                     else /* partially opaque */
3045
0
                     {
3046
0
                        entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
3047
0
                     }
3048
3049
0
                     *outrow = (png_byte)entry;
3050
0
                  }
3051
0
                  break;
3052
3053
0
               case PNG_CMAP_TRANS:
3054
0
                  for (; outrow < end_row; outrow += stepx)
3055
0
                  {
3056
0
                     png_byte gray = *inrow++;
3057
0
                     png_byte alpha = *inrow++;
3058
3059
0
                     if (alpha == 0)
3060
0
                        *outrow = PNG_CMAP_TRANS_BACKGROUND;
3061
3062
0
                     else if (gray != PNG_CMAP_TRANS_BACKGROUND)
3063
0
                        *outrow = gray;
3064
3065
0
                     else
3066
0
                        *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
3067
0
                  }
3068
0
                  break;
3069
3070
0
               case PNG_CMAP_RGB:
3071
0
                  for (; outrow < end_row; outrow += stepx)
3072
0
                  {
3073
0
                     *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
3074
0
                     inrow += 3;
3075
0
                  }
3076
0
                  break;
3077
3078
0
               case PNG_CMAP_RGB_ALPHA:
3079
0
                  for (; outrow < end_row; outrow += stepx)
3080
0
                  {
3081
0
                     unsigned int alpha = inrow[3];
3082
3083
                     /* Because the alpha entries only hold alpha==0.5 values
3084
                      * split the processing at alpha==0.25 (64) and 0.75
3085
                      * (196).
3086
                      */
3087
3088
0
                     if (alpha >= 196)
3089
0
                        *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
3090
0
                            inrow[2]);
3091
3092
0
                     else if (alpha < 64)
3093
0
                        *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
3094
3095
0
                     else
3096
0
                     {
3097
                        /* Likewise there are three entries for each of r, g
3098
                         * and b.  We could select the entry by popcount on
3099
                         * the top two bits on those architectures that
3100
                         * support it, this is what the code below does,
3101
                         * crudely.
3102
                         */
3103
0
                        unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
3104
3105
                        /* Here are how the values map:
3106
                         *
3107
                         * 0x00 .. 0x3f -> 0
3108
                         * 0x40 .. 0xbf -> 1
3109
                         * 0xc0 .. 0xff -> 2
3110
                         *
3111
                         * So, as above with the explicit alpha checks, the
3112
                         * breakpoints are at 64 and 196.
3113
                         */
3114
0
                        if (inrow[0] & 0x80) back_i += 9; /* red */
3115
0
                        if (inrow[0] & 0x40) back_i += 9;
3116
0
                        if (inrow[0] & 0x80) back_i += 3; /* green */
3117
0
                        if (inrow[0] & 0x40) back_i += 3;
3118
0
                        if (inrow[0] & 0x80) back_i += 1; /* blue */
3119
0
                        if (inrow[0] & 0x40) back_i += 1;
3120
3121
0
                        *outrow = (png_byte)back_i;
3122
0
                     }
3123
3124
0
                     inrow += 4;
3125
0
                  }
3126
0
                  break;
3127
3128
0
               default:
3129
0
                  break;
3130
0
            }
3131
0
         }
3132
0
      }
3133
0
   }
3134
3135
0
   return 1;
3136
0
}
3137
3138
static int
3139
png_image_read_colormapped(png_voidp argument)
3140
0
{
3141
0
   png_image_read_control *display = png_voidcast(png_image_read_control*,
3142
0
       argument);
3143
0
   png_imagep image = display->image;
3144
0
   png_controlp control = image->opaque;
3145
0
   png_structrp png_ptr = control->png_ptr;
3146
0
   png_inforp info_ptr = control->info_ptr;
3147
3148
0
   int passes = 0; /* As a flag */
3149
3150
0
   PNG_SKIP_CHUNKS(png_ptr);
3151
3152
   /* Update the 'info' structure and make sure the result is as required; first
3153
    * make sure to turn on the interlace handling if it will be required
3154
    * (because it can't be turned on *after* the call to png_read_update_info!)
3155
    */
3156
0
   if (display->colormap_processing == PNG_CMAP_NONE)
3157
0
      passes = png_set_interlace_handling(png_ptr);
3158
3159
0
   png_read_update_info(png_ptr, info_ptr);
3160
3161
   /* The expected output can be deduced from the colormap_processing option. */
3162
0
   switch (display->colormap_processing)
3163
0
   {
3164
0
      case PNG_CMAP_NONE:
3165
         /* Output must be one channel and one byte per pixel, the output
3166
          * encoding can be anything.
3167
          */
3168
0
         if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
3169
0
            info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
3170
0
            info_ptr->bit_depth == 8)
3171
0
            break;
3172
3173
0
         goto bad_output;
3174
3175
0
      case PNG_CMAP_TRANS:
3176
0
      case PNG_CMAP_GA:
3177
         /* Output must be two channels and the 'G' one must be sRGB, the latter
3178
          * can be checked with an exact number because it should have been set
3179
          * to this number above!
3180
          */
3181
0
         if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
3182
0
            info_ptr->bit_depth == 8 &&
3183
0
            png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3184
0
            image->colormap_entries == 256)
3185
0
            break;
3186
3187
0
         goto bad_output;
3188
3189
0
      case PNG_CMAP_RGB:
3190
         /* Output must be 8-bit sRGB encoded RGB */
3191
0
         if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
3192
0
            info_ptr->bit_depth == 8 &&
3193
0
            png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3194
0
            image->colormap_entries == 216)
3195
0
            break;
3196
3197
0
         goto bad_output;
3198
3199
0
      case PNG_CMAP_RGB_ALPHA:
3200
         /* Output must be 8-bit sRGB encoded RGBA */
3201
0
         if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
3202
0
            info_ptr->bit_depth == 8 &&
3203
0
            png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3204
0
            image->colormap_entries == 244 /* 216 + 1 + 27 */)
3205
0
            break;
3206
3207
0
         goto bad_output;
3208
3209
0
      default:
3210
0
      bad_output:
3211
0
         png_error(png_ptr, "bad color-map processing (internal error)");
3212
0
   }
3213
3214
   /* Now read the rows.  Do this here if it is possible to read directly into
3215
    * the output buffer, otherwise allocate a local row buffer of the maximum
3216
    * size libpng requires and call the relevant processing routine safely.
3217
    */
3218
0
   {
3219
0
      png_voidp first_row = display->buffer;
3220
0
      ptrdiff_t row_bytes = display->row_stride;
3221
3222
      /* The following expression is designed to work correctly whether it gives
3223
       * a signed or an unsigned result.
3224
       */
3225
0
      if (row_bytes < 0)
3226
0
      {
3227
0
         char *ptr = png_voidcast(char*, first_row);
3228
0
         ptr += (image->height-1) * (-row_bytes);
3229
0
         first_row = png_voidcast(png_voidp, ptr);
3230
0
      }
3231
3232
0
      display->first_row = first_row;
3233
0
      display->row_bytes = row_bytes;
3234
0
   }
3235
3236
0
   if (passes == 0)
3237
0
   {
3238
0
      int result;
3239
0
      png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
3240
3241
0
      display->local_row = row;
3242
0
      result = png_safe_execute(image, png_image_read_and_map, display);
3243
0
      display->local_row = NULL;
3244
0
      png_free(png_ptr, row);
3245
3246
0
      return result;
3247
0
   }
3248
3249
0
   else
3250
0
   {
3251
0
      png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
3252
3253
0
      while (--passes >= 0)
3254
0
      {
3255
0
         png_uint_32      y = image->height;
3256
0
         png_bytep        row = png_voidcast(png_bytep, display->first_row);
3257
3258
0
         for (; y > 0; --y)
3259
0
         {
3260
0
            png_read_row(png_ptr, row, NULL);
3261
0
            row += row_bytes;
3262
0
         }
3263
0
      }
3264
3265
0
      return 1;
3266
0
   }
3267
0
}
3268
3269
/* Just the row reading part of png_image_read. */
3270
static int
3271
png_image_read_composite(png_voidp argument)
3272
0
{
3273
0
   png_image_read_control *display = png_voidcast(png_image_read_control*,
3274
0
       argument);
3275
0
   png_imagep image = display->image;
3276
0
   png_structrp png_ptr = image->opaque->png_ptr;
3277
0
   int passes;
3278
3279
0
   switch (png_ptr->interlaced)
3280
0
   {
3281
0
      case PNG_INTERLACE_NONE:
3282
0
         passes = 1;
3283
0
         break;
3284
3285
0
      case PNG_INTERLACE_ADAM7:
3286
0
         passes = PNG_INTERLACE_ADAM7_PASSES;
3287
0
         break;
3288
3289
0
      default:
3290
0
         png_error(png_ptr, "unknown interlace type");
3291
0
   }
3292
3293
0
   {
3294
0
      png_uint_32  height = image->height;
3295
0
      png_uint_32  width = image->width;
3296
0
      ptrdiff_t    step_row = display->row_bytes;
3297
0
      unsigned int channels =
3298
0
          (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
3299
0
      int pass;
3300
3301
0
      for (pass = 0; pass < passes; ++pass)
3302
0
      {
3303
0
         unsigned int     startx, stepx, stepy;
3304
0
         png_uint_32      y;
3305
3306
0
         if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3307
0
         {
3308
            /* The row may be empty for a short image: */
3309
0
            if (PNG_PASS_COLS(width, pass) == 0)
3310
0
               continue;
3311
3312
0
            startx = PNG_PASS_START_COL(pass) * channels;
3313
0
            stepx = PNG_PASS_COL_OFFSET(pass) * channels;
3314
0
            y = PNG_PASS_START_ROW(pass);
3315
0
            stepy = PNG_PASS_ROW_OFFSET(pass);
3316
0
         }
3317
3318
0
         else
3319
0
         {
3320
0
            y = 0;
3321
0
            startx = 0;
3322
0
            stepx = channels;
3323
0
            stepy = 1;
3324
0
         }
3325
3326
0
         for (; y<height; y += stepy)
3327
0
         {
3328
0
            png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3329
0
            png_bytep outrow;
3330
0
            png_const_bytep end_row;
3331
3332
            /* Read the row, which is packed: */
3333
0
            png_read_row(png_ptr, inrow, NULL);
3334
3335
0
            outrow = png_voidcast(png_bytep, display->first_row);
3336
0
            outrow += y * step_row;
3337
0
            end_row = outrow + width * channels;
3338
3339
            /* Now do the composition on each pixel in this row. */
3340
0
            outrow += startx;
3341
0
            for (; outrow < end_row; outrow += stepx)
3342
0
            {
3343
0
               png_byte alpha = inrow[channels];
3344
3345
0
               if (alpha > 0) /* else no change to the output */
3346
0
               {
3347
0
                  unsigned int c;
3348
3349
0
                  for (c=0; c<channels; ++c)
3350
0
                  {
3351
0
                     png_uint_32 component = inrow[c];
3352
3353
0
                     if (alpha < 255) /* else just use component */
3354
0
                     {
3355
                        /* This is PNG_OPTIMIZED_ALPHA, the component value
3356
                         * is a linear 8-bit value.  Combine this with the
3357
                         * current outrow[c] value which is sRGB encoded.
3358
                         * Arithmetic here is 16-bits to preserve the output
3359
                         * values correctly.
3360
                         */
3361
0
                        component *= 257*255; /* =65535 */
3362
0
                        component += (255-alpha)*png_sRGB_table[outrow[c]];
3363
3364
                        /* So 'component' is scaled by 255*65535 and is
3365
                         * therefore appropriate for the sRGB to linear
3366
                         * conversion table.
3367
                         */
3368
0
                        component = PNG_sRGB_FROM_LINEAR(component);
3369
0
                     }
3370
3371
0
                     outrow[c] = (png_byte)component;
3372
0
                  }
3373
0
               }
3374
3375
0
               inrow += channels+1; /* components and alpha channel */
3376
0
            }
3377
0
         }
3378
0
      }
3379
0
   }
3380
3381
0
   return 1;
3382
0
}
3383
3384
/* The do_local_background case; called when all the following transforms are to
3385
 * be done:
3386
 *
3387
 * PNG_RGB_TO_GRAY
3388
 * PNG_COMPOSITE
3389
 * PNG_GAMMA
3390
 *
3391
 * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
3392
 * PNG_COMPOSITE code performs gamma correction, so we get double gamma
3393
 * correction.  The fix-up is to prevent the PNG_COMPOSITE operation from
3394
 * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
3395
 * row and handles the removal or pre-multiplication of the alpha channel.
3396
 */
3397
static int
3398
png_image_read_background(png_voidp argument)
3399
0
{
3400
0
   png_image_read_control *display = png_voidcast(png_image_read_control*,
3401
0
       argument);
3402
0
   png_imagep image = display->image;
3403
0
   png_structrp png_ptr = image->opaque->png_ptr;
3404
0
   png_inforp info_ptr = image->opaque->info_ptr;
3405
0
   png_uint_32 height = image->height;
3406
0
   png_uint_32 width = image->width;
3407
0
   int pass, passes;
3408
3409
   /* Double check the convoluted logic below.  We expect to get here with
3410
    * libpng doing rgb to gray and gamma correction but background processing
3411
    * left to the png_image_read_background function.  The rows libpng produce
3412
    * might be 8 or 16-bit but should always have two channels; gray plus alpha.
3413
    */
3414
0
   if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
3415
0
      png_error(png_ptr, "lost rgb to gray");
3416
3417
0
   if ((png_ptr->transformations & PNG_COMPOSE) != 0)
3418
0
      png_error(png_ptr, "unexpected compose");
3419
3420
0
   if (png_get_channels(png_ptr, info_ptr) != 2)
3421
0
      png_error(png_ptr, "lost/gained channels");
3422
3423
   /* Expect the 8-bit case to always remove the alpha channel */
3424
0
   if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
3425
0
      (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
3426
0
      png_error(png_ptr, "unexpected 8-bit transformation");
3427
3428
0
   switch (png_ptr->interlaced)
3429
0
   {
3430
0
      case PNG_INTERLACE_NONE:
3431
0
         passes = 1;
3432
0
         break;
3433
3434
0
      case PNG_INTERLACE_ADAM7:
3435
0
         passes = PNG_INTERLACE_ADAM7_PASSES;
3436
0
         break;
3437
3438
0
      default:
3439
0
         png_error(png_ptr, "unknown interlace type");
3440
0
   }
3441
3442
   /* Use direct access to info_ptr here because otherwise the simplified API
3443
    * would require PNG_EASY_ACCESS_SUPPORTED (just for this.)  Note this is
3444
    * checking the value after libpng expansions, not the original value in the
3445
    * PNG.
3446
    */
3447
0
   switch (info_ptr->bit_depth)
3448
0
   {
3449
0
      case 8:
3450
         /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
3451
          * to be removed by composing on a background: either the row if
3452
          * display->background is NULL or display->background->green if not.
3453
          * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
3454
          */
3455
0
         {
3456
0
            png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3457
0
            ptrdiff_t step_row = display->row_bytes;
3458
3459
0
            for (pass = 0; pass < passes; ++pass)
3460
0
            {
3461
0
               unsigned int     startx, stepx, stepy;
3462
0
               png_uint_32      y;
3463
3464
0
               if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3465
0
               {
3466
                  /* The row may be empty for a short image: */
3467
0
                  if (PNG_PASS_COLS(width, pass) == 0)
3468
0
                     continue;
3469
3470
0
                  startx = PNG_PASS_START_COL(pass);
3471
0
                  stepx = PNG_PASS_COL_OFFSET(pass);
3472
0
                  y = PNG_PASS_START_ROW(pass);
3473
0
                  stepy = PNG_PASS_ROW_OFFSET(pass);
3474
0
               }
3475
3476
0
               else
3477
0
               {
3478
0
                  y = 0;
3479
0
                  startx = 0;
3480
0
                  stepx = stepy = 1;
3481
0
               }
3482
3483
0
               if (display->background == NULL)
3484
0
               {
3485
0
                  for (; y<height; y += stepy)
3486
0
                  {
3487
0
                     png_bytep inrow = png_voidcast(png_bytep,
3488
0
                         display->local_row);
3489
0
                     png_bytep outrow = first_row + y * step_row;
3490
0
                     png_const_bytep end_row = outrow + width;
3491
3492
                     /* Read the row, which is packed: */
3493
0
                     png_read_row(png_ptr, inrow, NULL);
3494
3495
                     /* Now do the composition on each pixel in this row. */
3496
0
                     outrow += startx;
3497
0
                     for (; outrow < end_row; outrow += stepx)
3498
0
                     {
3499
0
                        png_byte alpha = inrow[1];
3500
3501
0
                        if (alpha > 0) /* else no change to the output */
3502
0
                        {
3503
0
                           png_uint_32 component = inrow[0];
3504
3505
0
                           if (alpha < 255) /* else just use component */
3506
0
                           {
3507
                              /* Since PNG_OPTIMIZED_ALPHA was not set it is
3508
                               * necessary to invert the sRGB transfer
3509
                               * function and multiply the alpha out.
3510
                               */
3511
0
                              component = png_sRGB_table[component] * alpha;
3512
0
                              component += png_sRGB_table[outrow[0]] *
3513
0
                                 (255-alpha);
3514
0
                              component = PNG_sRGB_FROM_LINEAR(component);
3515
0
                           }
3516
3517
0
                           outrow[0] = (png_byte)component;
3518
0
                        }
3519
3520
0
                        inrow += 2; /* gray and alpha channel */
3521
0
                     }
3522
0
                  }
3523
0
               }
3524
3525
0
               else /* constant background value */
3526
0
               {
3527
0
                  png_byte background8 = display->background->green;
3528
0
                  png_uint_16 background = png_sRGB_table[background8];
3529
3530
0
                  for (; y<height; y += stepy)
3531
0
                  {
3532
0
                     png_bytep inrow = png_voidcast(png_bytep,
3533
0
                         display->local_row);
3534
0
                     png_bytep outrow = first_row + y * step_row;
3535
0
                     png_const_bytep end_row = outrow + width;
3536
3537
                     /* Read the row, which is packed: */
3538
0
                     png_read_row(png_ptr, inrow, NULL);
3539
3540
                     /* Now do the composition on each pixel in this row. */
3541
0
                     outrow += startx;
3542
0
                     for (; outrow < end_row; outrow += stepx)
3543
0
                     {
3544
0
                        png_byte alpha = inrow[1];
3545
3546
0
                        if (alpha > 0) /* else use background */
3547
0
                        {
3548
0
                           png_uint_32 component = inrow[0];
3549
3550
0
                           if (alpha < 255) /* else just use component */
3551
0
                           {
3552
0
                              component = png_sRGB_table[component] * alpha;
3553
0
                              component += background * (255-alpha);
3554
0
                              component = PNG_sRGB_FROM_LINEAR(component);
3555
0
                           }
3556
3557
0
                           outrow[0] = (png_byte)component;
3558
0
                        }
3559
3560
0
                        else
3561
0
                           outrow[0] = background8;
3562
3563
0
                        inrow += 2; /* gray and alpha channel */
3564
0
                     }
3565
0
                  }
3566
0
               }
3567
0
            }
3568
0
         }
3569
0
         break;
3570
3571
0
      case 16:
3572
         /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
3573
          * still be done and, maybe, the alpha channel removed.  This code also
3574
          * handles the alpha-first option.
3575
          */
3576
0
         {
3577
0
            png_uint_16p first_row = png_voidcast(png_uint_16p,
3578
0
                display->first_row);
3579
            /* The division by two is safe because the caller passed in a
3580
             * stride which was multiplied by 2 (below) to get row_bytes.
3581
             */
3582
0
            ptrdiff_t    step_row = display->row_bytes / 2;
3583
0
            unsigned int preserve_alpha = (image->format &
3584
0
                PNG_FORMAT_FLAG_ALPHA) != 0;
3585
0
            unsigned int outchannels = 1U+preserve_alpha;
3586
0
            int swap_alpha = 0;
3587
3588
0
#           ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
3589
0
               if (preserve_alpha != 0 &&
3590
0
                   (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
3591
0
                  swap_alpha = 1;
3592
0
#           endif
3593
3594
0
            for (pass = 0; pass < passes; ++pass)
3595
0
            {
3596
0
               unsigned int     startx, stepx, stepy;
3597
0
               png_uint_32      y;
3598
3599
               /* The 'x' start and step are adjusted to output components here.
3600
                */
3601
0
               if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3602
0
               {
3603
                  /* The row may be empty for a short image: */
3604
0
                  if (PNG_PASS_COLS(width, pass) == 0)
3605
0
                     continue;
3606
3607
0
                  startx = PNG_PASS_START_COL(pass) * outchannels;
3608
0
                  stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
3609
0
                  y = PNG_PASS_START_ROW(pass);
3610
0
                  stepy = PNG_PASS_ROW_OFFSET(pass);
3611
0
               }
3612
3613
0
               else
3614
0
               {
3615
0
                  y = 0;
3616
0
                  startx = 0;
3617
0
                  stepx = outchannels;
3618
0
                  stepy = 1;
3619
0
               }
3620
3621
0
               for (; y<height; y += stepy)
3622
0
               {
3623
0
                  png_const_uint_16p inrow;
3624
0
                  png_uint_16p outrow = first_row + y*step_row;
3625
0
                  png_uint_16p end_row = outrow + width * outchannels;
3626
3627
                  /* Read the row, which is packed: */
3628
0
                  png_read_row(png_ptr, png_voidcast(png_bytep,
3629
0
                      display->local_row), NULL);
3630
0
                  inrow = png_voidcast(png_const_uint_16p, display->local_row);
3631
3632
                  /* Now do the pre-multiplication on each pixel in this row.
3633
                   */
3634
0
                  outrow += startx;
3635
0
                  for (; outrow < end_row; outrow += stepx)
3636
0
                  {
3637
0
                     png_uint_32 component = inrow[0];
3638
0
                     png_uint_16 alpha = inrow[1];
3639
3640
0
                     if (alpha > 0) /* else 0 */
3641
0
                     {
3642
0
                        if (alpha < 65535) /* else just use component */
3643
0
                        {
3644
0
                           component *= alpha;
3645
0
                           component += 32767;
3646
0
                           component /= 65535;
3647
0
                        }
3648
0
                     }
3649
3650
0
                     else
3651
0
                        component = 0;
3652
3653
0
                     outrow[swap_alpha] = (png_uint_16)component;
3654
0
                     if (preserve_alpha != 0)
3655
0
                        outrow[1 ^ swap_alpha] = alpha;
3656
3657
0
                     inrow += 2; /* components and alpha channel */
3658
0
                  }
3659
0
               }
3660
0
            }
3661
0
         }
3662
0
         break;
3663
3664
0
#ifdef __GNUC__
3665
0
      default:
3666
0
         png_error(png_ptr, "unexpected bit depth");
3667
0
#endif
3668
0
   }
3669
3670
0
   return 1;
3671
0
}
3672
3673
/* The guts of png_image_finish_read as a png_safe_execute callback. */
3674
static int
3675
png_image_read_direct(png_voidp argument)
3676
0
{
3677
0
   png_image_read_control *display = png_voidcast(png_image_read_control*,
3678
0
       argument);
3679
0
   png_imagep image = display->image;
3680
0
   png_structrp png_ptr = image->opaque->png_ptr;
3681
0
   png_inforp info_ptr = image->opaque->info_ptr;
3682
3683
0
   png_uint_32 format = image->format;
3684
0
   int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
3685
0
   int do_local_compose = 0;
3686
0
   int do_local_background = 0; /* to avoid double gamma correction bug */
3687
0
   int passes = 0;
3688
3689
   /* Add transforms to ensure the correct output format is produced then check
3690
    * that the required implementation support is there.  Always expand; always
3691
    * need 8 bits minimum, no palette and expanded tRNS.
3692
    */
3693
0
   png_set_expand(png_ptr);
3694
3695
   /* Now check the format to see if it was modified. */
3696
0
   {
3697
0
      png_uint_32 base_format = png_image_format(png_ptr) &
3698
0
         ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
3699
0
      png_uint_32 change = format ^ base_format;
3700
0
      png_fixed_point output_gamma;
3701
0
      int mode; /* alpha mode */
3702
3703
      /* Do this first so that we have a record if rgb to gray is happening. */
3704
0
      if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
3705
0
      {
3706
         /* gray<->color transformation required. */
3707
0
         if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3708
0
            png_set_gray_to_rgb(png_ptr);
3709
3710
0
         else
3711
0
         {
3712
            /* libpng can't do both rgb to gray and
3713
             * background/pre-multiplication if there is also significant gamma
3714
             * correction, because both operations require linear colors and
3715
             * the code only supports one transform doing the gamma correction.
3716
             * Handle this by doing the pre-multiplication or background
3717
             * operation in this code, if necessary.
3718
             *
3719
             * TODO: fix this by rewriting pngrtran.c (!)
3720
             *
3721
             * For the moment (given that fixing this in pngrtran.c is an
3722
             * enormous change) 'do_local_background' is used to indicate that
3723
             * the problem exists.
3724
             */
3725
0
            if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3726
0
               do_local_background = 1/*maybe*/;
3727
3728
0
            png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
3729
0
                PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
3730
0
         }
3731
3732
0
         change &= ~PNG_FORMAT_FLAG_COLOR;
3733
0
      }
3734
3735
      /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
3736
       */
3737
0
      {
3738
0
         png_fixed_point input_gamma_default;
3739
3740
0
         if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3741
0
             (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
3742
0
            input_gamma_default = PNG_GAMMA_LINEAR;
3743
0
         else
3744
0
            input_gamma_default = PNG_DEFAULT_sRGB;
3745
3746
         /* Call png_set_alpha_mode to set the default for the input gamma; the
3747
          * output gamma is set by a second call below.
3748
          */
3749
0
         png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
3750
0
      }
3751
3752
0
      if (linear != 0)
3753
0
      {
3754
         /* If there *is* an alpha channel in the input it must be multiplied
3755
          * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
3756
          */
3757
0
         if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3758
0
            mode = PNG_ALPHA_STANDARD; /* associated alpha */
3759
3760
0
         else
3761
0
            mode = PNG_ALPHA_PNG;
3762
3763
0
         output_gamma = PNG_GAMMA_LINEAR;
3764
0
      }
3765
3766
0
      else
3767
0
      {
3768
0
         mode = PNG_ALPHA_PNG;
3769
0
         output_gamma = PNG_DEFAULT_sRGB;
3770
0
      }
3771
3772
0
      if ((change & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0)
3773
0
      {
3774
0
         mode = PNG_ALPHA_OPTIMIZED;
3775
0
         change &= ~PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
3776
0
      }
3777
3778
      /* If 'do_local_background' is set check for the presence of gamma
3779
       * correction; this is part of the work-round for the libpng bug
3780
       * described above.
3781
       *
3782
       * TODO: fix libpng and remove this.
3783
       */
3784
0
      if (do_local_background != 0)
3785
0
      {
3786
0
         png_fixed_point gtest;
3787
3788
         /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
3789
          * gamma correction, the screen gamma hasn't been set on png_struct
3790
          * yet; it's set below.  png_struct::gamma, however, is set to the
3791
          * final value.
3792
          */
3793
0
         if (png_muldiv(&gtest, output_gamma, png_ptr->colorspace.gamma,
3794
0
             PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
3795
0
            do_local_background = 0;
3796
3797
0
         else if (mode == PNG_ALPHA_STANDARD)
3798
0
         {
3799
0
            do_local_background = 2/*required*/;
3800
0
            mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
3801
0
         }
3802
3803
         /* else leave as 1 for the checks below */
3804
0
      }
3805
3806
      /* If the bit-depth changes then handle that here. */
3807
0
      if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
3808
0
      {
3809
0
         if (linear != 0 /*16-bit output*/)
3810
0
            png_set_expand_16(png_ptr);
3811
3812
0
         else /* 8-bit output */
3813
0
            png_set_scale_16(png_ptr);
3814
3815
0
         change &= ~PNG_FORMAT_FLAG_LINEAR;
3816
0
      }
3817
3818
      /* Now the background/alpha channel changes. */
3819
0
      if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
3820
0
      {
3821
         /* Removing an alpha channel requires composition for the 8-bit
3822
          * formats; for the 16-bit it is already done, above, by the
3823
          * pre-multiplication and the channel just needs to be stripped.
3824
          */
3825
0
         if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3826
0
         {
3827
            /* If RGB->gray is happening the alpha channel must be left and the
3828
             * operation completed locally.
3829
             *
3830
             * TODO: fix libpng and remove this.
3831
             */
3832
0
            if (do_local_background != 0)
3833
0
               do_local_background = 2/*required*/;
3834
3835
            /* 16-bit output: just remove the channel */
3836
0
            else if (linear != 0) /* compose on black (well, pre-multiply) */
3837
0
               png_set_strip_alpha(png_ptr);
3838
3839
            /* 8-bit output: do an appropriate compose */
3840
0
            else if (display->background != NULL)
3841
0
            {
3842
0
               png_color_16 c;
3843
3844
0
               c.index = 0; /*unused*/
3845
0
               c.red = display->background->red;
3846
0
               c.green = display->background->green;
3847
0
               c.blue = display->background->blue;
3848
0
               c.gray = display->background->green;
3849
3850
               /* This is always an 8-bit sRGB value, using the 'green' channel
3851
                * for gray is much better than calculating the luminance here;
3852
                * we can get off-by-one errors in that calculation relative to
3853
                * the app expectations and that will show up in transparent
3854
                * pixels.
3855
                */
3856
0
               png_set_background_fixed(png_ptr, &c,
3857
0
                   PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
3858
0
                   0/*gamma: not used*/);
3859
0
            }
3860
3861
0
            else /* compose on row: implemented below. */
3862
0
            {
3863
0
               do_local_compose = 1;
3864
               /* This leaves the alpha channel in the output, so it has to be
3865
                * removed by the code below.  Set the encoding to the 'OPTIMIZE'
3866
                * one so the code only has to hack on the pixels that require
3867
                * composition.
3868
                */
3869
0
               mode = PNG_ALPHA_OPTIMIZED;
3870
0
            }
3871
0
         }
3872
3873
0
         else /* output needs an alpha channel */
3874
0
         {
3875
            /* This is tricky because it happens before the swap operation has
3876
             * been accomplished; however, the swap does *not* swap the added
3877
             * alpha channel (weird API), so it must be added in the correct
3878
             * place.
3879
             */
3880
0
            png_uint_32 filler; /* opaque filler */
3881
0
            int where;
3882
3883
0
            if (linear != 0)
3884
0
               filler = 65535;
3885
3886
0
            else
3887
0
               filler = 255;
3888
3889
0
#ifdef PNG_FORMAT_AFIRST_SUPPORTED
3890
0
            if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
3891
0
            {
3892
0
               where = PNG_FILLER_BEFORE;
3893
0
               change &= ~PNG_FORMAT_FLAG_AFIRST;
3894
0
            }
3895
3896
0
            else
3897
0
#endif
3898
0
            where = PNG_FILLER_AFTER;
3899
3900
0
            png_set_add_alpha(png_ptr, filler, where);
3901
0
         }
3902
3903
         /* This stops the (irrelevant) call to swap_alpha below. */
3904
0
         change &= ~PNG_FORMAT_FLAG_ALPHA;
3905
0
      }
3906
3907
      /* Now set the alpha mode correctly; this is always done, even if there is
3908
       * no alpha channel in either the input or the output because it correctly
3909
       * sets the output gamma.
3910
       */
3911
0
      png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
3912
3913
0
#     ifdef PNG_FORMAT_BGR_SUPPORTED
3914
0
         if ((change & PNG_FORMAT_FLAG_BGR) != 0)
3915
0
         {
3916
            /* Check only the output format; PNG is never BGR; don't do this if
3917
             * the output is gray, but fix up the 'format' value in that case.
3918
             */
3919
0
            if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3920
0
               png_set_bgr(png_ptr);
3921
3922
0
            else
3923
0
               format &= ~PNG_FORMAT_FLAG_BGR;
3924
3925
0
            change &= ~PNG_FORMAT_FLAG_BGR;
3926
0
         }
3927
0
#     endif
3928
3929
0
#     ifdef PNG_FORMAT_AFIRST_SUPPORTED
3930
0
         if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
3931
0
         {
3932
            /* Only relevant if there is an alpha channel - it's particularly
3933
             * important to handle this correctly because do_local_compose may
3934
             * be set above and then libpng will keep the alpha channel for this
3935
             * code to remove.
3936
             */
3937
0
            if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
3938
0
            {
3939
               /* Disable this if doing a local background,
3940
                * TODO: remove this when local background is no longer required.
3941
                */
3942
0
               if (do_local_background != 2)
3943
0
                  png_set_swap_alpha(png_ptr);
3944
0
            }
3945
3946
0
            else
3947
0
               format &= ~PNG_FORMAT_FLAG_AFIRST;
3948
3949
0
            change &= ~PNG_FORMAT_FLAG_AFIRST;
3950
0
         }
3951
0
#     endif
3952
3953
      /* If the *output* is 16-bit then we need to check for a byte-swap on this
3954
       * architecture.
3955
       */
3956
0
      if (linear != 0)
3957
0
      {
3958
0
         png_uint_16 le = 0x0001;
3959
3960
0
         if ((*(png_const_bytep) & le) != 0)
3961
0
            png_set_swap(png_ptr);
3962
0
      }
3963
3964
      /* If change is not now 0 some transformation is missing - error out. */
3965
0
      if (change != 0)
3966
0
         png_error(png_ptr, "png_read_image: unsupported transformation");
3967
0
   }
3968
3969
0
   PNG_SKIP_CHUNKS(png_ptr);
3970
3971
   /* Update the 'info' structure and make sure the result is as required; first
3972
    * make sure to turn on the interlace handling if it will be required
3973
    * (because it can't be turned on *after* the call to png_read_update_info!)
3974
    *
3975
    * TODO: remove the do_local_background fixup below.
3976
    */
3977
0
   if (do_local_compose == 0 && do_local_background != 2)
3978
0
      passes = png_set_interlace_handling(png_ptr);
3979
3980
0
   png_read_update_info(png_ptr, info_ptr);
3981
3982
0
   {
3983
0
      png_uint_32 info_format = 0;
3984
3985
0
      if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
3986
0
         info_format |= PNG_FORMAT_FLAG_COLOR;
3987
3988
0
      if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
3989
0
      {
3990
         /* do_local_compose removes this channel below. */
3991
0
         if (do_local_compose == 0)
3992
0
         {
3993
            /* do_local_background does the same if required. */
3994
0
            if (do_local_background != 2 ||
3995
0
               (format & PNG_FORMAT_FLAG_ALPHA) != 0)
3996
0
               info_format |= PNG_FORMAT_FLAG_ALPHA;
3997
0
         }
3998
0
      }
3999
4000
0
      else if (do_local_compose != 0) /* internal error */
4001
0
         png_error(png_ptr, "png_image_read: alpha channel lost");
4002
4003
0
      if ((format & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) {
4004
0
         info_format |= PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
4005
0
      }
4006
4007
0
      if (info_ptr->bit_depth == 16)
4008
0
         info_format |= PNG_FORMAT_FLAG_LINEAR;
4009
4010
0
#ifdef PNG_FORMAT_BGR_SUPPORTED
4011
0
      if ((png_ptr->transformations & PNG_BGR) != 0)
4012
0
         info_format |= PNG_FORMAT_FLAG_BGR;
4013
0
#endif
4014
4015
0
#ifdef PNG_FORMAT_AFIRST_SUPPORTED
4016
0
         if (do_local_background == 2)
4017
0
         {
4018
0
            if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4019
0
               info_format |= PNG_FORMAT_FLAG_AFIRST;
4020
0
         }
4021
4022
0
         if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
4023
0
            ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
4024
0
            (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
4025
0
         {
4026
0
            if (do_local_background == 2)
4027
0
               png_error(png_ptr, "unexpected alpha swap transformation");
4028
4029
0
            info_format |= PNG_FORMAT_FLAG_AFIRST;
4030
0
         }
4031
0
#     endif
4032
4033
      /* This is actually an internal error. */
4034
0
      if (info_format != format)
4035
0
         png_error(png_ptr, "png_read_image: invalid transformations");
4036
0
   }
4037
4038
   /* Now read the rows.  If do_local_compose is set then it is necessary to use
4039
    * a local row buffer.  The output will be GA, RGBA or BGRA and must be
4040
    * converted to G, RGB or BGR as appropriate.  The 'local_row' member of the
4041
    * display acts as a flag.
4042
    */
4043
0
   {
4044
0
      png_voidp first_row = display->buffer;
4045
0
      ptrdiff_t row_bytes = display->row_stride;
4046
4047
0
      if (linear != 0)
4048
0
         row_bytes *= 2;
4049
4050
      /* The following expression is designed to work correctly whether it gives
4051
       * a signed or an unsigned result.
4052
       */
4053
0
      if (row_bytes < 0)
4054
0
      {
4055
0
         char *ptr = png_voidcast(char*, first_row);
4056
0
         ptr += (image->height-1) * (-row_bytes);
4057
0
         first_row = png_voidcast(png_voidp, ptr);
4058
0
      }
4059
4060
0
      display->first_row = first_row;
4061
0
      display->row_bytes = row_bytes;
4062
0
   }
4063
4064
0
   if (do_local_compose != 0)
4065
0
   {
4066
0
      int result;
4067
0
      png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4068
4069
0
      display->local_row = row;
4070
0
      result = png_safe_execute(image, png_image_read_composite, display);
4071
0
      display->local_row = NULL;
4072
0
      png_free(png_ptr, row);
4073
4074
0
      return result;
4075
0
   }
4076
4077
0
   else if (do_local_background == 2)
4078
0
   {
4079
0
      int result;
4080
0
      png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4081
4082
0
      display->local_row = row;
4083
0
      result = png_safe_execute(image, png_image_read_background, display);
4084
0
      display->local_row = NULL;
4085
0
      png_free(png_ptr, row);
4086
4087
0
      return result;
4088
0
   }
4089
4090
0
   else
4091
0
   {
4092
0
      png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
4093
4094
0
      while (--passes >= 0)
4095
0
      {
4096
0
         png_uint_32      y = image->height;
4097
0
         png_bytep        row = png_voidcast(png_bytep, display->first_row);
4098
4099
0
         for (; y > 0; --y)
4100
0
         {
4101
0
            png_read_row(png_ptr, row, NULL);
4102
0
            row += row_bytes;
4103
0
         }
4104
0
      }
4105
4106
0
      return 1;
4107
0
   }
4108
0
}
4109
4110
int PNGAPI
4111
png_image_finish_read(png_imagep image, png_const_colorp background,
4112
    void *buffer, png_int_32 row_stride, void *colormap)
4113
0
{
4114
0
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
4115
0
   {
4116
      /* Check for row_stride overflow.  This check is not performed on the
4117
       * original PNG format because it may not occur in the output PNG format
4118
       * and libpng deals with the issues of reading the original.
4119
       */
4120
0
      unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
4121
4122
      /* The following checks just the 'row_stride' calculation to ensure it
4123
       * fits in a signed 32-bit value.  Because channels/components can be
4124
       * either 1 or 2 bytes in size the length of a row can still overflow 32
4125
       * bits; this is just to verify that the 'row_stride' argument can be
4126
       * represented.
4127
       */
4128
0
      if (image->width <= 0x7fffffffU/channels) /* no overflow */
4129
0
      {
4130
0
         png_uint_32 check;
4131
0
         png_uint_32 png_row_stride = image->width * channels;
4132
4133
0
         if (row_stride == 0)
4134
0
            row_stride = (png_int_32)/*SAFE*/png_row_stride;
4135
4136
0
         if (row_stride < 0)
4137
0
            check = (png_uint_32)(-row_stride);
4138
4139
0
         else
4140
0
            check = (png_uint_32)row_stride;
4141
4142
         /* This verifies 'check', the absolute value of the actual stride
4143
          * passed in and detects overflow in the application calculation (i.e.
4144
          * if the app did actually pass in a non-zero 'row_stride'.
4145
          */
4146
0
         if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
4147
0
         {
4148
            /* Now check for overflow of the image buffer calculation; this
4149
             * limits the whole image size to 32 bits for API compatibility with
4150
             * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
4151
             *
4152
             * The PNG_IMAGE_BUFFER_SIZE macro is:
4153
             *
4154
             *    (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
4155
             *
4156
             * And the component size is always 1 or 2, so make sure that the
4157
             * number of *bytes* that the application is saying are available
4158
             * does actually fit into a 32-bit number.
4159
             *
4160
             * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
4161
             * will be changed to use png_alloc_size_t; bigger images can be
4162
             * accommodated on 64-bit systems.
4163
             */
4164
0
            if (image->height <=
4165
0
                0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
4166
0
            {
4167
0
               if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
4168
0
                  (image->colormap_entries > 0 && colormap != NULL))
4169
0
               {
4170
0
                  int result;
4171
0
                  png_image_read_control display;
4172
4173
0
                  memset(&display, 0, (sizeof display));
4174
0
                  display.image = image;
4175
0
                  display.buffer = buffer;
4176
0
                  display.row_stride = row_stride;
4177
0
                  display.colormap = colormap;
4178
0
                  display.background = background;
4179
0
                  display.local_row = NULL;
4180
4181
                  /* Choose the correct 'end' routine; for the color-map case
4182
                   * all the setup has already been done.
4183
                   */
4184
0
                  if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
4185
0
                     result =
4186
0
                         png_safe_execute(image,
4187
0
                             png_image_read_colormap, &display) &&
4188
0
                             png_safe_execute(image,
4189
0
                             png_image_read_colormapped, &display);
4190
4191
0
                  else
4192
0
                     result =
4193
0
                        png_safe_execute(image,
4194
0
                            png_image_read_direct, &display);
4195
4196
0
                  png_image_free(image);
4197
0
                  return result;
4198
0
               }
4199
4200
0
               else
4201
0
                  return png_image_error(image,
4202
0
                      "png_image_finish_read[color-map]: no color-map");
4203
0
            }
4204
4205
0
            else
4206
0
               return png_image_error(image,
4207
0
                   "png_image_finish_read: image too large");
4208
0
         }
4209
4210
0
         else
4211
0
            return png_image_error(image,
4212
0
                "png_image_finish_read: invalid argument");
4213
0
      }
4214
4215
0
      else
4216
0
         return png_image_error(image,
4217
0
             "png_image_finish_read: row_stride too large");
4218
0
   }
4219
4220
0
   else if (image != NULL)
4221
0
      return png_image_error(image,
4222
0
          "png_image_finish_read: damaged PNG_IMAGE_VERSION");
4223
4224
0
   return 0;
4225
0
}
4226
4227
#endif /* SIMPLIFIED_READ */
4228
#endif /* READ */