1
2 /* pngrutil.c - utilities to read a PNG file
3 *
4 * Last changed in libpng 1.6.10 [March 6, 2014]
5 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 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 are only called from within
14 * libpng itself during the course of reading an image.
15 */
16
17 #include "pngpriv.h"
18
19 #ifdef PNG_READ_SUPPORTED
20
21 png_uint_32 PNGAPI
png_get_uint_31(png_const_structrp png_ptr,png_const_bytep buf)22 png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
23 {
24 png_uint_32 uval = png_get_uint_32(buf);
25
26 if (uval > PNG_UINT_31_MAX)
27 png_error(png_ptr, "PNG unsigned integer out of range");
28
29 return (uval);
30 }
31
32 #if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
33 /* The following is a variation on the above for use with the fixed
34 * point values used for gAMA and cHRM. Instead of png_error it
35 * issues a warning and returns (-1) - an invalid value because both
36 * gAMA and cHRM use *unsigned* integers for fixed point values.
37 */
38 #define PNG_FIXED_ERROR (-1)
39
40 static png_fixed_point /* PRIVATE */
png_get_fixed_point(png_structrp png_ptr,png_const_bytep buf)41 png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
42 {
43 png_uint_32 uval = png_get_uint_32(buf);
44
45 if (uval <= PNG_UINT_31_MAX)
46 return (png_fixed_point)uval; /* known to be in range */
47
48 /* The caller can turn off the warning by passing NULL. */
49 if (png_ptr != NULL)
50 png_warning(png_ptr, "PNG fixed point integer out of range");
51
52 return PNG_FIXED_ERROR;
53 }
54 #endif
55
56 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
57 /* NOTE: the read macros will obscure these definitions, so that if
58 * PNG_USE_READ_MACROS is set the library will not use them internally,
59 * but the APIs will still be available externally.
60 *
61 * The parentheses around "PNGAPI function_name" in the following three
62 * functions are necessary because they allow the macros to co-exist with
63 * these (unused but exported) functions.
64 */
65
66 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
png_uint_32(PNGAPI png_get_uint_32)67 png_uint_32 (PNGAPI
68 png_get_uint_32)(png_const_bytep buf)
69 {
70 png_uint_32 uval =
71 ((png_uint_32)(*(buf )) << 24) +
72 ((png_uint_32)(*(buf + 1)) << 16) +
73 ((png_uint_32)(*(buf + 2)) << 8) +
74 ((png_uint_32)(*(buf + 3)) ) ;
75
76 return uval;
77 }
78
79 /* Grab a signed 32-bit integer from a buffer in big-endian format. The
80 * data is stored in the PNG file in two's complement format and there
81 * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
82 * the following code does a two's complement to native conversion.
83 */
png_int_32(PNGAPI png_get_int_32)84 png_int_32 (PNGAPI
85 png_get_int_32)(png_const_bytep buf)
86 {
87 png_uint_32 uval = png_get_uint_32(buf);
88 if ((uval & 0x80000000) == 0) /* non-negative */
89 return uval;
90
91 uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */
92 return -(png_int_32)uval;
93 }
94
95 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
png_uint_16(PNGAPI png_get_uint_16)96 png_uint_16 (PNGAPI
97 png_get_uint_16)(png_const_bytep buf)
98 {
99 /* ANSI-C requires an int value to accomodate at least 16 bits so this
100 * works and allows the compiler not to worry about possible narrowing
101 * on 32 bit systems. (Pre-ANSI systems did not make integers smaller
102 * than 16 bits either.)
103 */
104 unsigned int val =
105 ((unsigned int)(*buf) << 8) +
106 ((unsigned int)(*(buf + 1)));
107
108 return (png_uint_16)val;
109 }
110
111 #endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
112
113 /* Read and check the PNG file signature */
114 void /* PRIVATE */
png_read_sig(png_structrp png_ptr,png_inforp info_ptr)115 png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
116 {
117 png_size_t num_checked, num_to_check;
118
119 /* Exit if the user application does not expect a signature. */
120 if (png_ptr->sig_bytes >= 8)
121 return;
122
123 num_checked = png_ptr->sig_bytes;
124 num_to_check = 8 - num_checked;
125
126 #ifdef PNG_IO_STATE_SUPPORTED
127 png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
128 #endif
129
130 /* The signature must be serialized in a single I/O call. */
131 png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
132 png_ptr->sig_bytes = 8;
133
134 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
135 {
136 if (num_checked < 4 &&
137 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
138 png_error(png_ptr, "Not a PNG file");
139 else
140 png_error(png_ptr, "PNG file corrupted by ASCII conversion");
141 }
142 if (num_checked < 3)
143 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
144 }
145
146 /* Read the chunk header (length + type name).
147 * Put the type name into png_ptr->chunk_name, and return the length.
148 */
149 png_uint_32 /* PRIVATE */
png_read_chunk_header(png_structrp png_ptr)150 png_read_chunk_header(png_structrp png_ptr)
151 {
152 png_byte buf[8];
153 png_uint_32 length;
154
155 #ifdef PNG_IO_STATE_SUPPORTED
156 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
157 #endif
158
159 /* Read the length and the chunk name.
160 * This must be performed in a single I/O call.
161 */
162 png_read_data(png_ptr, buf, 8);
163 length = png_get_uint_31(png_ptr, buf);
164
165 /* Put the chunk name into png_ptr->chunk_name. */
166 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
167
168 png_debug2(0, "Reading %lx chunk, length = %lu",
169 (unsigned long)png_ptr->chunk_name, (unsigned long)length);
170
171 /* Reset the crc and run it over the chunk name. */
172 png_reset_crc(png_ptr);
173 png_calculate_crc(png_ptr, buf + 4, 4);
174
175 /* Check to see if chunk name is valid. */
176 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
177
178 #ifdef PNG_IO_STATE_SUPPORTED
179 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
180 #endif
181
182 return length;
183 }
184
185 /* Read data, and (optionally) run it through the CRC. */
186 void /* PRIVATE */
png_crc_read(png_structrp png_ptr,png_bytep buf,png_uint_32 length)187 png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
188 {
189 if (png_ptr == NULL)
190 return;
191
192 png_read_data(png_ptr, buf, length);
193 png_calculate_crc(png_ptr, buf, length);
194 }
195
196 /* Optionally skip data and then check the CRC. Depending on whether we
197 * are reading an ancillary or critical chunk, and how the program has set
198 * things up, we may calculate the CRC on the data and print a message.
199 * Returns '1' if there was a CRC error, '0' otherwise.
200 */
201 int /* PRIVATE */
png_crc_finish(png_structrp png_ptr,png_uint_32 skip)202 png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
203 {
204 /* The size of the local buffer for inflate is a good guess as to a
205 * reasonable size to use for buffering reads from the application.
206 */
207 while (skip > 0)
208 {
209 png_uint_32 len;
210 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
211
212 len = (sizeof tmpbuf);
213 if (len > skip)
214 len = skip;
215 skip -= len;
216
217 png_crc_read(png_ptr, tmpbuf, len);
218 }
219
220 if (png_crc_error(png_ptr))
221 {
222 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) ?
223 !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
224 (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
225 {
226 png_chunk_warning(png_ptr, "CRC error");
227 }
228
229 else
230 png_chunk_error(png_ptr, "CRC error");
231
232 return (1);
233 }
234
235 return (0);
236 }
237
238 #ifdef PNG_INDEX_SUPPORTED
239 /* If tile index is used to skip over data and decode a partial image
240 * the crc value may be incorrect.
241 * The crc will only be calculated for the partial data read,
242 * not the entire data, which will result in an incorrect crc value.
243 * This function treats a png_crc_error as a warning, as opposed to the
244 * original function png_crc_finish, which will treat it as an error.
245 */
246 int /* PRIVATE */
png_opt_crc_finish(png_structrp png_ptr,png_uint_32 skip)247 png_opt_crc_finish(png_structrp png_ptr, png_uint_32 skip)
248 {
249 while (skip > 0)
250 {
251 png_uint_32 len;
252 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
253
254 len = (sizeof tmpbuf);
255 if (len > skip)
256 len = skip;
257 skip -= len;
258
259 png_crc_read(png_ptr, tmpbuf, len);
260 }
261
262 if (png_crc_error(png_ptr))
263 {
264 png_chunk_warning(png_ptr, "CRC error");
265 return (1);
266 }
267
268 return (0);
269 }
270 #endif
271
272 /* Compare the CRC stored in the PNG file with that calculated by libpng from
273 * the data it has read thus far.
274 */
275 int /* PRIVATE */
png_crc_error(png_structrp png_ptr)276 png_crc_error(png_structrp png_ptr)
277 {
278 png_byte crc_bytes[4];
279 png_uint_32 crc;
280 int need_crc = 1;
281
282 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
283 {
284 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
285 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
286 need_crc = 0;
287 }
288
289 else /* critical */
290 {
291 if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
292 need_crc = 0;
293 }
294
295 #ifdef PNG_IO_STATE_SUPPORTED
296 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
297 #endif
298
299 /* The chunk CRC must be serialized in a single I/O call. */
300 png_read_data(png_ptr, crc_bytes, 4);
301
302 if (need_crc)
303 {
304 crc = png_get_uint_32(crc_bytes);
305 return ((int)(crc != png_ptr->crc));
306 }
307
308 else
309 return (0);
310 }
311
312 #if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
313 defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
314 defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
315 defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
316 /* Manage the read buffer; this simply reallocates the buffer if it is not small
317 * enough (or if it is not allocated). The routine returns a pointer to the
318 * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
319 * it will call png_error (via png_malloc) on failure. (warn == 2 means
320 * 'silent').
321 */
322 static png_bytep
png_read_buffer(png_structrp png_ptr,png_alloc_size_t new_size,int warn)323 png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
324 {
325 png_bytep buffer = png_ptr->read_buffer;
326
327 if (buffer != NULL && new_size > png_ptr->read_buffer_size)
328 {
329 png_ptr->read_buffer = NULL;
330 png_ptr->read_buffer = NULL;
331 png_ptr->read_buffer_size = 0;
332 png_free(png_ptr, buffer);
333 buffer = NULL;
334 }
335
336 if (buffer == NULL)
337 {
338 buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
339
340 if (buffer != NULL)
341 {
342 png_ptr->read_buffer = buffer;
343 png_ptr->read_buffer_size = new_size;
344 }
345
346 else if (warn < 2) /* else silent */
347 {
348 if (warn)
349 png_chunk_warning(png_ptr, "insufficient memory to read chunk");
350
351 else
352 png_chunk_error(png_ptr, "insufficient memory to read chunk");
353 }
354 }
355
356 return buffer;
357 }
358 #endif /* PNG_READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
359
360 /* png_inflate_claim: claim the zstream for some nefarious purpose that involves
361 * decompression. Returns Z_OK on success, else a zlib error code. It checks
362 * the owner but, in final release builds, just issues a warning if some other
363 * chunk apparently owns the stream. Prior to release it does a png_error.
364 */
365 static int
png_inflate_claim(png_structrp png_ptr,png_uint_32 owner)366 png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
367 {
368 if (png_ptr->zowner != 0)
369 {
370 char msg[64];
371
372 PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
373 /* So the message that results is "<chunk> using zstream"; this is an
374 * internal error, but is very useful for debugging. i18n requirements
375 * are minimal.
376 */
377 (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
378 # if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
379 png_chunk_warning(png_ptr, msg);
380 png_ptr->zowner = 0;
381 # else
382 png_chunk_error(png_ptr, msg);
383 # endif
384 }
385
386 /* Implementation note: unlike 'png_deflate_claim' this internal function
387 * does not take the size of the data as an argument. Some efficiency could
388 * be gained by using this when it is known *if* the zlib stream itself does
389 * not record the number; however, this is an illusion: the original writer
390 * of the PNG may have selected a lower window size, and we really must
391 * follow that because, for systems with with limited capabilities, we
392 * would otherwise reject the application's attempts to use a smaller window
393 * size (zlib doesn't have an interface to say "this or lower"!).
394 *
395 * inflateReset2 was added to zlib 1.2.4; before this the window could not be
396 * reset, therefore it is necessary to always allocate the maximum window
397 * size with earlier zlibs just in case later compressed chunks need it.
398 */
399 {
400 int ret; /* zlib return code */
401 # if PNG_ZLIB_VERNUM >= 0x1240
402
403 # if defined(PNG_SET_OPTION_SUPPORTED) && \
404 defined(PNG_MAXIMUM_INFLATE_WINDOW)
405 int window_bits;
406
407 if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
408 PNG_OPTION_ON)
409 window_bits = 15;
410
411 else
412 window_bits = 0;
413 # else
414 # define window_bits 0
415 # endif
416 # endif
417
418 /* Set this for safety, just in case the previous owner left pointers to
419 * memory allocations.
420 */
421 png_ptr->zstream.next_in = NULL;
422 png_ptr->zstream.avail_in = 0;
423 png_ptr->zstream.next_out = NULL;
424 png_ptr->zstream.avail_out = 0;
425
426 if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
427 {
428 # if PNG_ZLIB_VERNUM < 0x1240
429 ret = inflateReset(&png_ptr->zstream);
430 # else
431 ret = inflateReset2(&png_ptr->zstream, window_bits);
432 # endif
433 }
434
435 else
436 {
437 # if PNG_ZLIB_VERNUM < 0x1240
438 ret = inflateInit(&png_ptr->zstream);
439 # else
440 ret = inflateInit2(&png_ptr->zstream, window_bits);
441 # endif
442
443 if (ret == Z_OK)
444 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
445 }
446
447 if (ret == Z_OK)
448 png_ptr->zowner = owner;
449
450 else
451 png_zstream_error(png_ptr, ret);
452
453 return ret;
454 }
455
456 # ifdef window_bits
457 # undef window_bits
458 # endif
459 }
460
461 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
462 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
463 * allow the caller to do multiple calls if required. If the 'finish' flag is
464 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
465 * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
466 * Z_OK or Z_STREAM_END will be returned on success.
467 *
468 * The input and output sizes are updated to the actual amounts of data consumed
469 * or written, not the amount available (as in a z_stream). The data pointers
470 * are not changed, so the next input is (data+input_size) and the next
471 * available output is (output+output_size).
472 */
473 static int
png_inflate(png_structrp png_ptr,png_uint_32 owner,int finish,png_const_bytep input,png_uint_32p input_size_ptr,png_bytep output,png_alloc_size_t * output_size_ptr)474 png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
475 /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
476 /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
477 {
478 if (png_ptr->zowner == owner) /* Else not claimed */
479 {
480 int ret;
481 png_alloc_size_t avail_out = *output_size_ptr;
482 png_uint_32 avail_in = *input_size_ptr;
483
484 /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
485 * can't even necessarily handle 65536 bytes) because the type uInt is
486 * "16 bits or more". Consequently it is necessary to chunk the input to
487 * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
488 * maximum value that can be stored in a uInt.) It is possible to set
489 * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
490 * a performance advantage, because it reduces the amount of data accessed
491 * at each step and that may give the OS more time to page it in.
492 */
493 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
494 /* avail_in and avail_out are set below from 'size' */
495 png_ptr->zstream.avail_in = 0;
496 png_ptr->zstream.avail_out = 0;
497
498 /* Read directly into the output if it is available (this is set to
499 * a local buffer below if output is NULL).
500 */
501 if (output != NULL)
502 png_ptr->zstream.next_out = output;
503
504 do
505 {
506 uInt avail;
507 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
508
509 /* zlib INPUT BUFFER */
510 /* The setting of 'avail_in' used to be outside the loop; by setting it
511 * inside it is possible to chunk the input to zlib and simply rely on
512 * zlib to advance the 'next_in' pointer. This allows arbitrary
513 * amounts of data to be passed through zlib at the unavoidable cost of
514 * requiring a window save (memcpy of up to 32768 output bytes)
515 * every ZLIB_IO_MAX input bytes.
516 */
517 avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
518
519 avail = ZLIB_IO_MAX;
520
521 if (avail_in < avail)
522 avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
523
524 avail_in -= avail;
525 png_ptr->zstream.avail_in = avail;
526
527 /* zlib OUTPUT BUFFER */
528 avail_out += png_ptr->zstream.avail_out; /* not written last time */
529
530 avail = ZLIB_IO_MAX; /* maximum zlib can process */
531
532 if (output == NULL)
533 {
534 /* Reset the output buffer each time round if output is NULL and
535 * make available the full buffer, up to 'remaining_space'
536 */
537 png_ptr->zstream.next_out = local_buffer;
538 if ((sizeof local_buffer) < avail)
539 avail = (sizeof local_buffer);
540 }
541
542 if (avail_out < avail)
543 avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
544
545 png_ptr->zstream.avail_out = avail;
546 avail_out -= avail;
547
548 /* zlib inflate call */
549 /* In fact 'avail_out' may be 0 at this point, that happens at the end
550 * of the read when the final LZ end code was not passed at the end of
551 * the previous chunk of input data. Tell zlib if we have reached the
552 * end of the output buffer.
553 */
554 ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH :
555 (finish ? Z_FINISH : Z_SYNC_FLUSH));
556 } while (ret == Z_OK);
557
558 /* For safety kill the local buffer pointer now */
559 if (output == NULL)
560 png_ptr->zstream.next_out = NULL;
561
562 /* Claw back the 'size' and 'remaining_space' byte counts. */
563 avail_in += png_ptr->zstream.avail_in;
564 avail_out += png_ptr->zstream.avail_out;
565
566 /* Update the input and output sizes; the updated values are the amount
567 * consumed or written, effectively the inverse of what zlib uses.
568 */
569 if (avail_out > 0)
570 *output_size_ptr -= avail_out;
571
572 if (avail_in > 0)
573 *input_size_ptr -= avail_in;
574
575 /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
576 png_zstream_error(png_ptr, ret);
577 return ret;
578 }
579
580 else
581 {
582 /* This is a bad internal error. The recovery assigns to the zstream msg
583 * pointer, which is not owned by the caller, but this is safe; it's only
584 * used on errors!
585 */
586 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
587 return Z_STREAM_ERROR;
588 }
589 }
590
591 /*
592 * Decompress trailing data in a chunk. The assumption is that read_buffer
593 * points at an allocated area holding the contents of a chunk with a
594 * trailing compressed part. What we get back is an allocated area
595 * holding the original prefix part and an uncompressed version of the
596 * trailing part (the malloc area passed in is freed).
597 */
598 static int
png_decompress_chunk(png_structrp png_ptr,png_uint_32 chunklength,png_uint_32 prefix_size,png_alloc_size_t * newlength,int terminate)599 png_decompress_chunk(png_structrp png_ptr,
600 png_uint_32 chunklength, png_uint_32 prefix_size,
601 png_alloc_size_t *newlength /* must be initialized to the maximum! */,
602 int terminate /*add a '\0' to the end of the uncompressed data*/)
603 {
604 /* TODO: implement different limits for different types of chunk.
605 *
606 * The caller supplies *newlength set to the maximum length of the
607 * uncompressed data, but this routine allocates space for the prefix and
608 * maybe a '\0' terminator too. We have to assume that 'prefix_size' is
609 * limited only by the maximum chunk size.
610 */
611 png_alloc_size_t limit = PNG_SIZE_MAX;
612
613 # ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
614 if (png_ptr->user_chunk_malloc_max > 0 &&
615 png_ptr->user_chunk_malloc_max < limit)
616 limit = png_ptr->user_chunk_malloc_max;
617 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
618 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
619 limit = PNG_USER_CHUNK_MALLOC_MAX;
620 # endif
621
622 if (limit >= prefix_size + (terminate != 0))
623 {
624 int ret;
625
626 limit -= prefix_size + (terminate != 0);
627
628 if (limit < *newlength)
629 *newlength = limit;
630
631 /* Now try to claim the stream. */
632 ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
633
634 if (ret == Z_OK)
635 {
636 png_uint_32 lzsize = chunklength - prefix_size;
637
638 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
639 /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
640 /* output: */ NULL, newlength);
641
642 if (ret == Z_STREAM_END)
643 {
644 /* Use 'inflateReset' here, not 'inflateReset2' because this
645 * preserves the previously decided window size (otherwise it would
646 * be necessary to store the previous window size.) In practice
647 * this doesn't matter anyway, because png_inflate will call inflate
648 * with Z_FINISH in almost all cases, so the window will not be
649 * maintained.
650 */
651 if (inflateReset(&png_ptr->zstream) == Z_OK)
652 {
653 /* Because of the limit checks above we know that the new,
654 * expanded, size will fit in a size_t (let alone an
655 * png_alloc_size_t). Use png_malloc_base here to avoid an
656 * extra OOM message.
657 */
658 png_alloc_size_t new_size = *newlength;
659 png_alloc_size_t buffer_size = prefix_size + new_size +
660 (terminate != 0);
661 png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
662 buffer_size));
663
664 if (text != NULL)
665 {
666 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
667 png_ptr->read_buffer + prefix_size, &lzsize,
668 text + prefix_size, newlength);
669
670 if (ret == Z_STREAM_END)
671 {
672 if (new_size == *newlength)
673 {
674 if (terminate)
675 text[prefix_size + *newlength] = 0;
676
677 if (prefix_size > 0)
678 memcpy(text, png_ptr->read_buffer, prefix_size);
679
680 {
681 png_bytep old_ptr = png_ptr->read_buffer;
682
683 png_ptr->read_buffer = text;
684 png_ptr->read_buffer_size = buffer_size;
685 text = old_ptr; /* freed below */
686 }
687 }
688
689 else
690 {
691 /* The size changed on the second read, there can be no
692 * guarantee that anything is correct at this point.
693 * The 'msg' pointer has been set to "unexpected end of
694 * LZ stream", which is fine, but return an error code
695 * that the caller won't accept.
696 */
697 ret = PNG_UNEXPECTED_ZLIB_RETURN;
698 }
699 }
700
701 else if (ret == Z_OK)
702 ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
703
704 /* Free the text pointer (this is the old read_buffer on
705 * success)
706 */
707 png_free(png_ptr, text);
708
709 /* This really is very benign, but it's still an error because
710 * the extra space may otherwise be used as a Trojan Horse.
711 */
712 if (ret == Z_STREAM_END &&
713 chunklength - prefix_size != lzsize)
714 png_chunk_benign_error(png_ptr, "extra compressed data");
715 }
716
717 else
718 {
719 /* Out of memory allocating the buffer */
720 ret = Z_MEM_ERROR;
721 png_zstream_error(png_ptr, Z_MEM_ERROR);
722 }
723 }
724
725 else
726 {
727 /* inflateReset failed, store the error message */
728 png_zstream_error(png_ptr, ret);
729
730 if (ret == Z_STREAM_END)
731 ret = PNG_UNEXPECTED_ZLIB_RETURN;
732 }
733 }
734
735 else if (ret == Z_OK)
736 ret = PNG_UNEXPECTED_ZLIB_RETURN;
737
738 /* Release the claimed stream */
739 png_ptr->zowner = 0;
740 }
741
742 else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
743 ret = PNG_UNEXPECTED_ZLIB_RETURN;
744
745 return ret;
746 }
747
748 else
749 {
750 /* Application/configuration limits exceeded */
751 png_zstream_error(png_ptr, Z_MEM_ERROR);
752 return Z_MEM_ERROR;
753 }
754 }
755 #endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
756
757 #ifdef PNG_READ_iCCP_SUPPORTED
758 /* Perform a partial read and decompress, producing 'avail_out' bytes and
759 * reading from the current chunk as required.
760 */
761 static int
png_inflate_read(png_structrp png_ptr,png_bytep read_buffer,uInt read_size,png_uint_32p chunk_bytes,png_bytep next_out,png_alloc_size_t * out_size,int finish)762 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
763 png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
764 int finish)
765 {
766 if (png_ptr->zowner == png_ptr->chunk_name)
767 {
768 int ret;
769
770 /* next_in and avail_in must have been initialized by the caller. */
771 png_ptr->zstream.next_out = next_out;
772 png_ptr->zstream.avail_out = 0; /* set in the loop */
773
774 do
775 {
776 if (png_ptr->zstream.avail_in == 0)
777 {
778 if (read_size > *chunk_bytes)
779 read_size = (uInt)*chunk_bytes;
780 *chunk_bytes -= read_size;
781
782 if (read_size > 0)
783 png_crc_read(png_ptr, read_buffer, read_size);
784
785 png_ptr->zstream.next_in = read_buffer;
786 png_ptr->zstream.avail_in = read_size;
787 }
788
789 if (png_ptr->zstream.avail_out == 0)
790 {
791 uInt avail = ZLIB_IO_MAX;
792 if (avail > *out_size)
793 avail = (uInt)*out_size;
794 *out_size -= avail;
795
796 png_ptr->zstream.avail_out = avail;
797 }
798
799 /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
800 * the available output is produced; this allows reading of truncated
801 * streams.
802 */
803 ret = inflate(&png_ptr->zstream,
804 *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
805 }
806 while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
807
808 *out_size += png_ptr->zstream.avail_out;
809 png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
810
811 /* Ensure the error message pointer is always set: */
812 png_zstream_error(png_ptr, ret);
813 return ret;
814 }
815
816 else
817 {
818 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
819 return Z_STREAM_ERROR;
820 }
821 }
822 #endif
823
824 /* Read and check the IDHR chunk */
825 void /* PRIVATE */
png_handle_IHDR(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)826 png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
827 {
828 png_byte buf[13];
829 png_uint_32 width, height;
830 int bit_depth, color_type, compression_type, filter_type;
831 int interlace_type;
832
833 png_debug(1, "in png_handle_IHDR");
834
835 if (png_ptr->mode & PNG_HAVE_IHDR)
836 png_chunk_error(png_ptr, "out of place");
837
838 /* Check the length */
839 if (length != 13)
840 png_chunk_error(png_ptr, "invalid");
841
842 png_ptr->mode |= PNG_HAVE_IHDR;
843
844 png_crc_read(png_ptr, buf, 13);
845 png_crc_finish(png_ptr, 0);
846
847 width = png_get_uint_31(png_ptr, buf);
848 height = png_get_uint_31(png_ptr, buf + 4);
849 bit_depth = buf[8];
850 color_type = buf[9];
851 compression_type = buf[10];
852 filter_type = buf[11];
853 interlace_type = buf[12];
854
855 /* Set internal variables */
856 png_ptr->width = width;
857 png_ptr->height = height;
858 png_ptr->bit_depth = (png_byte)bit_depth;
859 png_ptr->interlaced = (png_byte)interlace_type;
860 png_ptr->color_type = (png_byte)color_type;
861 #ifdef PNG_MNG_FEATURES_SUPPORTED
862 png_ptr->filter_type = (png_byte)filter_type;
863 #endif
864 png_ptr->compression_type = (png_byte)compression_type;
865
866 /* Find number of channels */
867 switch (png_ptr->color_type)
868 {
869 default: /* invalid, png_set_IHDR calls png_error */
870 case PNG_COLOR_TYPE_GRAY:
871 case PNG_COLOR_TYPE_PALETTE:
872 png_ptr->channels = 1;
873 break;
874
875 case PNG_COLOR_TYPE_RGB:
876 png_ptr->channels = 3;
877 break;
878
879 case PNG_COLOR_TYPE_GRAY_ALPHA:
880 png_ptr->channels = 2;
881 break;
882
883 case PNG_COLOR_TYPE_RGB_ALPHA:
884 png_ptr->channels = 4;
885 break;
886 }
887
888 /* Set up other useful info */
889 png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
890 png_ptr->channels);
891 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
892 png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
893 png_debug1(3, "channels = %d", png_ptr->channels);
894 png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
895 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
896 color_type, interlace_type, compression_type, filter_type);
897 }
898
899 /* Read and check the palette */
900 void /* PRIVATE */
png_handle_PLTE(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)901 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
902 {
903 png_color palette[PNG_MAX_PALETTE_LENGTH];
904 int num, i;
905 #ifdef PNG_POINTER_INDEXING_SUPPORTED
906 png_colorp pal_ptr;
907 #endif
908
909 png_debug(1, "in png_handle_PLTE");
910
911 if (!(png_ptr->mode & PNG_HAVE_IHDR))
912 png_chunk_error(png_ptr, "missing IHDR");
913
914 /* Moved to before the 'after IDAT' check below because otherwise duplicate
915 * PLTE chunks are potentially ignored (the spec says there shall not be more
916 * than one PLTE, the error is not treated as benign, so this check trumps
917 * the requirement that PLTE appears before IDAT.)
918 */
919 else if (png_ptr->mode & PNG_HAVE_PLTE)
920 png_chunk_error(png_ptr, "duplicate");
921
922 else if (png_ptr->mode & PNG_HAVE_IDAT)
923 {
924 /* This is benign because the non-benign error happened before, when an
925 * IDAT was encountered in a color-mapped image with no PLTE.
926 */
927 png_crc_finish(png_ptr, length);
928 png_chunk_benign_error(png_ptr, "out of place");
929 return;
930 }
931
932 png_ptr->mode |= PNG_HAVE_PLTE;
933
934 if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
935 {
936 png_crc_finish(png_ptr, length);
937 png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
938 return;
939 }
940
941 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
942 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
943 {
944 png_crc_finish(png_ptr, length);
945 return;
946 }
947 #endif
948
949 if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
950 {
951 png_crc_finish(png_ptr, length);
952
953 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
954 png_chunk_benign_error(png_ptr, "invalid");
955
956 else
957 png_chunk_error(png_ptr, "invalid");
958
959 return;
960 }
961
962 /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
963 num = (int)length / 3;
964
965 #ifdef PNG_POINTER_INDEXING_SUPPORTED
966 for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
967 {
968 png_byte buf[3];
969
970 png_crc_read(png_ptr, buf, 3);
971 pal_ptr->red = buf[0];
972 pal_ptr->green = buf[1];
973 pal_ptr->blue = buf[2];
974 }
975 #else
976 for (i = 0; i < num; i++)
977 {
978 png_byte buf[3];
979
980 png_crc_read(png_ptr, buf, 3);
981 /* Don't depend upon png_color being any order */
982 palette[i].red = buf[0];
983 palette[i].green = buf[1];
984 palette[i].blue = buf[2];
985 }
986 #endif
987
988 /* If we actually need the PLTE chunk (ie for a paletted image), we do
989 * whatever the normal CRC configuration tells us. However, if we
990 * have an RGB image, the PLTE can be considered ancillary, so
991 * we will act as though it is.
992 */
993 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
994 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
995 #endif
996 {
997 png_crc_finish(png_ptr, 0);
998 }
999
1000 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1001 else if (png_crc_error(png_ptr)) /* Only if we have a CRC error */
1002 {
1003 /* If we don't want to use the data from an ancillary chunk,
1004 * we have two options: an error abort, or a warning and we
1005 * ignore the data in this chunk (which should be OK, since
1006 * it's considered ancillary for a RGB or RGBA image).
1007 *
1008 * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
1009 * chunk type to determine whether to check the ancillary or the critical
1010 * flags.
1011 */
1012 if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
1013 {
1014 if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
1015 return;
1016
1017 else
1018 png_chunk_error(png_ptr, "CRC error");
1019 }
1020
1021 /* Otherwise, we (optionally) emit a warning and use the chunk. */
1022 else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
1023 png_chunk_warning(png_ptr, "CRC error");
1024 }
1025 #endif
1026
1027 /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
1028 * own copy of the palette. This has the side effect that when png_start_row
1029 * is called (this happens after any call to png_read_update_info) the
1030 * info_ptr palette gets changed. This is extremely unexpected and
1031 * confusing.
1032 *
1033 * Fix this by not sharing the palette in this way.
1034 */
1035 png_set_PLTE(png_ptr, info_ptr, palette, num);
1036
1037 /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
1038 * IDAT. Prior to 1.6.0 this was not checked; instead the code merely
1039 * checked the apparent validity of a tRNS chunk inserted before PLTE on a
1040 * palette PNG. 1.6.0 attempts to rigorously follow the standard and
1041 * therefore does a benign error if the erroneous condition is detected *and*
1042 * cancels the tRNS if the benign error returns. The alternative is to
1043 * amend the standard since it would be rather hypocritical of the standards
1044 * maintainers to ignore it.
1045 */
1046 #ifdef PNG_READ_tRNS_SUPPORTED
1047 if (png_ptr->num_trans > 0 ||
1048 (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
1049 {
1050 /* Cancel this because otherwise it would be used if the transforms
1051 * require it. Don't cancel the 'valid' flag because this would prevent
1052 * detection of duplicate chunks.
1053 */
1054 png_ptr->num_trans = 0;
1055
1056 if (info_ptr != NULL)
1057 info_ptr->num_trans = 0;
1058
1059 png_chunk_benign_error(png_ptr, "tRNS must be after");
1060 }
1061 #endif
1062
1063 #ifdef PNG_READ_hIST_SUPPORTED
1064 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
1065 png_chunk_benign_error(png_ptr, "hIST must be after");
1066 #endif
1067
1068 #ifdef PNG_READ_bKGD_SUPPORTED
1069 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1070 png_chunk_benign_error(png_ptr, "bKGD must be after");
1071 #endif
1072 }
1073
1074 void /* PRIVATE */
png_handle_IEND(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1075 png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1076 {
1077 png_debug(1, "in png_handle_IEND");
1078
1079 if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
1080 png_chunk_error(png_ptr, "out of place");
1081
1082 png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
1083
1084 png_crc_finish(png_ptr, length);
1085
1086 if (length != 0)
1087 png_chunk_benign_error(png_ptr, "invalid");
1088
1089 PNG_UNUSED(info_ptr)
1090 }
1091
1092 #ifdef PNG_READ_gAMA_SUPPORTED
1093 void /* PRIVATE */
png_handle_gAMA(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1094 png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1095 {
1096 png_fixed_point igamma;
1097 png_byte buf[4];
1098
1099 png_debug(1, "in png_handle_gAMA");
1100
1101 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1102 png_chunk_error(png_ptr, "missing IHDR");
1103
1104 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1105 {
1106 png_crc_finish(png_ptr, length);
1107 png_chunk_benign_error(png_ptr, "out of place");
1108 return;
1109 }
1110
1111 if (length != 4)
1112 {
1113 png_crc_finish(png_ptr, length);
1114 png_chunk_benign_error(png_ptr, "invalid");
1115 return;
1116 }
1117
1118 png_crc_read(png_ptr, buf, 4);
1119
1120 if (png_crc_finish(png_ptr, 0))
1121 return;
1122
1123 igamma = png_get_fixed_point(NULL, buf);
1124
1125 png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
1126 png_colorspace_sync(png_ptr, info_ptr);
1127 }
1128 #endif
1129
1130 #ifdef PNG_READ_sBIT_SUPPORTED
1131 void /* PRIVATE */
png_handle_sBIT(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1132 png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1133 {
1134 unsigned int truelen, i;
1135 png_byte sample_depth;
1136 png_byte buf[4];
1137
1138 png_debug(1, "in png_handle_sBIT");
1139
1140 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1141 png_chunk_error(png_ptr, "missing IHDR");
1142
1143 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1144 {
1145 png_crc_finish(png_ptr, length);
1146 png_chunk_benign_error(png_ptr, "out of place");
1147 return;
1148 }
1149
1150 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
1151 {
1152 png_crc_finish(png_ptr, length);
1153 png_chunk_benign_error(png_ptr, "duplicate");
1154 return;
1155 }
1156
1157 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1158 {
1159 truelen = 3;
1160 sample_depth = 8;
1161 }
1162
1163 else
1164 {
1165 truelen = png_ptr->channels;
1166 sample_depth = png_ptr->bit_depth;
1167 }
1168
1169 if (length != truelen || length > 4)
1170 {
1171 png_chunk_benign_error(png_ptr, "invalid");
1172 png_crc_finish(png_ptr, length);
1173 return;
1174 }
1175
1176 buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
1177 png_crc_read(png_ptr, buf, truelen);
1178
1179 if (png_crc_finish(png_ptr, 0))
1180 return;
1181
1182 for (i=0; i<truelen; ++i)
1183 if (buf[i] == 0 || buf[i] > sample_depth)
1184 {
1185 png_chunk_benign_error(png_ptr, "invalid");
1186 return;
1187 }
1188
1189 if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
1190 {
1191 png_ptr->sig_bit.red = buf[0];
1192 png_ptr->sig_bit.green = buf[1];
1193 png_ptr->sig_bit.blue = buf[2];
1194 png_ptr->sig_bit.alpha = buf[3];
1195 }
1196
1197 else
1198 {
1199 png_ptr->sig_bit.gray = buf[0];
1200 png_ptr->sig_bit.red = buf[0];
1201 png_ptr->sig_bit.green = buf[0];
1202 png_ptr->sig_bit.blue = buf[0];
1203 png_ptr->sig_bit.alpha = buf[1];
1204 }
1205
1206 png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
1207 }
1208 #endif
1209
1210 #ifdef PNG_READ_cHRM_SUPPORTED
1211 void /* PRIVATE */
png_handle_cHRM(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1212 png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1213 {
1214 png_byte buf[32];
1215 png_xy xy;
1216
1217 png_debug(1, "in png_handle_cHRM");
1218
1219 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1220 png_chunk_error(png_ptr, "missing IHDR");
1221
1222 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1223 {
1224 png_crc_finish(png_ptr, length);
1225 png_chunk_benign_error(png_ptr, "out of place");
1226 return;
1227 }
1228
1229 if (length != 32)
1230 {
1231 png_crc_finish(png_ptr, length);
1232 png_chunk_benign_error(png_ptr, "invalid");
1233 return;
1234 }
1235
1236 png_crc_read(png_ptr, buf, 32);
1237
1238 if (png_crc_finish(png_ptr, 0))
1239 return;
1240
1241 xy.whitex = png_get_fixed_point(NULL, buf);
1242 xy.whitey = png_get_fixed_point(NULL, buf + 4);
1243 xy.redx = png_get_fixed_point(NULL, buf + 8);
1244 xy.redy = png_get_fixed_point(NULL, buf + 12);
1245 xy.greenx = png_get_fixed_point(NULL, buf + 16);
1246 xy.greeny = png_get_fixed_point(NULL, buf + 20);
1247 xy.bluex = png_get_fixed_point(NULL, buf + 24);
1248 xy.bluey = png_get_fixed_point(NULL, buf + 28);
1249
1250 if (xy.whitex == PNG_FIXED_ERROR ||
1251 xy.whitey == PNG_FIXED_ERROR ||
1252 xy.redx == PNG_FIXED_ERROR ||
1253 xy.redy == PNG_FIXED_ERROR ||
1254 xy.greenx == PNG_FIXED_ERROR ||
1255 xy.greeny == PNG_FIXED_ERROR ||
1256 xy.bluex == PNG_FIXED_ERROR ||
1257 xy.bluey == PNG_FIXED_ERROR)
1258 {
1259 png_chunk_benign_error(png_ptr, "invalid values");
1260 return;
1261 }
1262
1263 /* If a colorspace error has already been output skip this chunk */
1264 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1265 return;
1266
1267 if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM)
1268 {
1269 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1270 png_colorspace_sync(png_ptr, info_ptr);
1271 png_chunk_benign_error(png_ptr, "duplicate");
1272 return;
1273 }
1274
1275 png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
1276 (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1277 1/*prefer cHRM values*/);
1278 png_colorspace_sync(png_ptr, info_ptr);
1279 }
1280 #endif
1281
1282 #ifdef PNG_READ_sRGB_SUPPORTED
1283 void /* PRIVATE */
png_handle_sRGB(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1284 png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1285 {
1286 png_byte intent;
1287
1288 png_debug(1, "in png_handle_sRGB");
1289
1290 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1291 png_chunk_error(png_ptr, "missing IHDR");
1292
1293 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1294 {
1295 png_crc_finish(png_ptr, length);
1296 png_chunk_benign_error(png_ptr, "out of place");
1297 return;
1298 }
1299
1300 if (length != 1)
1301 {
1302 png_crc_finish(png_ptr, length);
1303 png_chunk_benign_error(png_ptr, "invalid");
1304 return;
1305 }
1306
1307 png_crc_read(png_ptr, &intent, 1);
1308
1309 if (png_crc_finish(png_ptr, 0))
1310 return;
1311
1312 /* If a colorspace error has already been output skip this chunk */
1313 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1314 return;
1315
1316 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1317 * this.
1318 */
1319 if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT)
1320 {
1321 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1322 png_colorspace_sync(png_ptr, info_ptr);
1323 png_chunk_benign_error(png_ptr, "too many profiles");
1324 return;
1325 }
1326
1327 (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
1328 png_colorspace_sync(png_ptr, info_ptr);
1329 }
1330 #endif /* PNG_READ_sRGB_SUPPORTED */
1331
1332 #ifdef PNG_READ_iCCP_SUPPORTED
1333 void /* PRIVATE */
png_handle_iCCP(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1334 png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1335 /* Note: this does not properly handle profiles that are > 64K under DOS */
1336 {
1337 png_const_charp errmsg = NULL; /* error message output, or no error */
1338 int finished = 0; /* crc checked */
1339
1340 png_debug(1, "in png_handle_iCCP");
1341
1342 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1343 png_chunk_error(png_ptr, "missing IHDR");
1344
1345 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1346 {
1347 png_crc_finish(png_ptr, length);
1348 png_chunk_benign_error(png_ptr, "out of place");
1349 return;
1350 }
1351
1352 /* Consistent with all the above colorspace handling an obviously *invalid*
1353 * chunk is just ignored, so does not invalidate the color space. An
1354 * alternative is to set the 'invalid' flags at the start of this routine
1355 * and only clear them in they were not set before and all the tests pass.
1356 * The minimum 'deflate' stream is assumed to be just the 2 byte header and 4
1357 * byte checksum. The keyword must be one character and there is a
1358 * terminator (0) byte and the compression method.
1359 */
1360 if (length < 9)
1361 {
1362 png_crc_finish(png_ptr, length);
1363 png_chunk_benign_error(png_ptr, "too short");
1364 return;
1365 }
1366
1367 /* If a colorspace error has already been output skip this chunk */
1368 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1369 {
1370 png_crc_finish(png_ptr, length);
1371 return;
1372 }
1373
1374 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1375 * this.
1376 */
1377 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
1378 {
1379 uInt read_length, keyword_length;
1380 char keyword[81];
1381
1382 /* Find the keyword; the keyword plus separator and compression method
1383 * bytes can be at most 81 characters long.
1384 */
1385 read_length = 81; /* maximum */
1386 if (read_length > length)
1387 read_length = (uInt)length;
1388
1389 png_crc_read(png_ptr, (png_bytep)keyword, read_length);
1390 length -= read_length;
1391
1392 keyword_length = 0;
1393 while (keyword_length < 80 && keyword_length < read_length &&
1394 keyword[keyword_length] != 0)
1395 ++keyword_length;
1396
1397 /* TODO: make the keyword checking common */
1398 if (keyword_length >= 1 && keyword_length <= 79)
1399 {
1400 /* We only understand '0' compression - deflate - so if we get a
1401 * different value we can't safely decode the chunk.
1402 */
1403 if (keyword_length+1 < read_length &&
1404 keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
1405 {
1406 read_length -= keyword_length+2;
1407
1408 if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
1409 {
1410 Byte profile_header[132];
1411 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
1412 png_alloc_size_t size = (sizeof profile_header);
1413
1414 png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
1415 png_ptr->zstream.avail_in = read_length;
1416 (void)png_inflate_read(png_ptr, local_buffer,
1417 (sizeof local_buffer), &length, profile_header, &size,
1418 0/*finish: don't, because the output is too small*/);
1419
1420 if (size == 0)
1421 {
1422 /* We have the ICC profile header; do the basic header checks.
1423 */
1424 const png_uint_32 profile_length =
1425 png_get_uint_32(profile_header);
1426
1427 if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
1428 keyword, profile_length))
1429 {
1430 /* The length is apparently ok, so we can check the 132
1431 * byte header.
1432 */
1433 if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
1434 keyword, profile_length, profile_header,
1435 png_ptr->color_type))
1436 {
1437 /* Now read the tag table; a variable size buffer is
1438 * needed at this point, allocate one for the whole
1439 * profile. The header check has already validated
1440 * that none of these stuff will overflow.
1441 */
1442 const png_uint_32 tag_count = png_get_uint_32(
1443 profile_header+128);
1444 png_bytep profile = png_read_buffer(png_ptr,
1445 profile_length, 2/*silent*/);
1446
1447 if (profile != NULL)
1448 {
1449 memcpy(profile, profile_header,
1450 (sizeof profile_header));
1451
1452 size = 12 * tag_count;
1453
1454 (void)png_inflate_read(png_ptr, local_buffer,
1455 (sizeof local_buffer), &length,
1456 profile + (sizeof profile_header), &size, 0);
1457
1458 /* Still expect a buffer error because we expect
1459 * there to be some tag data!
1460 */
1461 if (size == 0)
1462 {
1463 if (png_icc_check_tag_table(png_ptr,
1464 &png_ptr->colorspace, keyword, profile_length,
1465 profile))
1466 {
1467 /* The profile has been validated for basic
1468 * security issues, so read the whole thing in.
1469 */
1470 size = profile_length - (sizeof profile_header)
1471 - 12 * tag_count;
1472
1473 (void)png_inflate_read(png_ptr, local_buffer,
1474 (sizeof local_buffer), &length,
1475 profile + (sizeof profile_header) +
1476 12 * tag_count, &size, 1/*finish*/);
1477
1478 if (length > 0 && !(png_ptr->flags &
1479 PNG_FLAG_BENIGN_ERRORS_WARN))
1480 errmsg = "extra compressed data";
1481
1482 /* But otherwise allow extra data: */
1483 else if (size == 0)
1484 {
1485 if (length > 0)
1486 {
1487 /* This can be handled completely, so
1488 * keep going.
1489 */
1490 png_chunk_warning(png_ptr,
1491 "extra compressed data");
1492 }
1493
1494 png_crc_finish(png_ptr, length);
1495 finished = 1;
1496
1497 # ifdef PNG_sRGB_SUPPORTED
1498 /* Check for a match against sRGB */
1499 png_icc_set_sRGB(png_ptr,
1500 &png_ptr->colorspace, profile,
1501 png_ptr->zstream.adler);
1502 # endif
1503
1504 /* Steal the profile for info_ptr. */
1505 if (info_ptr != NULL)
1506 {
1507 png_free_data(png_ptr, info_ptr,
1508 PNG_FREE_ICCP, 0);
1509
1510 info_ptr->iccp_name = png_voidcast(char*,
1511 png_malloc_base(png_ptr,
1512 keyword_length+1));
1513 if (info_ptr->iccp_name != NULL)
1514 {
1515 memcpy(info_ptr->iccp_name, keyword,
1516 keyword_length+1);
1517 info_ptr->iccp_proflen =
1518 profile_length;
1519 info_ptr->iccp_profile = profile;
1520 png_ptr->read_buffer = NULL; /*steal*/
1521 info_ptr->free_me |= PNG_FREE_ICCP;
1522 info_ptr->valid |= PNG_INFO_iCCP;
1523 }
1524
1525 else
1526 {
1527 png_ptr->colorspace.flags |=
1528 PNG_COLORSPACE_INVALID;
1529 errmsg = "out of memory";
1530 }
1531 }
1532
1533 /* else the profile remains in the read
1534 * buffer which gets reused for subsequent
1535 * chunks.
1536 */
1537
1538 if (info_ptr != NULL)
1539 png_colorspace_sync(png_ptr, info_ptr);
1540
1541 if (errmsg == NULL)
1542 {
1543 png_ptr->zowner = 0;
1544 return;
1545 }
1546 }
1547
1548 else if (size > 0)
1549 errmsg = "truncated";
1550
1551 else
1552 errmsg = png_ptr->zstream.msg;
1553 }
1554
1555 /* else png_icc_check_tag_table output an error */
1556 }
1557
1558 else /* profile truncated */
1559 errmsg = png_ptr->zstream.msg;
1560 }
1561
1562 else
1563 errmsg = "out of memory";
1564 }
1565
1566 /* else png_icc_check_header output an error */
1567 }
1568
1569 /* else png_icc_check_length output an error */
1570 }
1571
1572 else /* profile truncated */
1573 errmsg = png_ptr->zstream.msg;
1574
1575 /* Release the stream */
1576 png_ptr->zowner = 0;
1577 }
1578
1579 else /* png_inflate_claim failed */
1580 errmsg = png_ptr->zstream.msg;
1581 }
1582
1583 else
1584 errmsg = "bad compression method"; /* or missing */
1585 }
1586
1587 else
1588 errmsg = "bad keyword";
1589 }
1590
1591 else
1592 errmsg = "too many profiles";
1593
1594 /* Failure: the reason is in 'errmsg' */
1595 if (!finished)
1596 png_crc_finish(png_ptr, length);
1597
1598 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1599 png_colorspace_sync(png_ptr, info_ptr);
1600 if (errmsg != NULL) /* else already output */
1601 png_chunk_benign_error(png_ptr, errmsg);
1602 }
1603 #endif /* PNG_READ_iCCP_SUPPORTED */
1604
1605 #ifdef PNG_READ_sPLT_SUPPORTED
1606 void /* PRIVATE */
png_handle_sPLT(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1607 png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1608 /* Note: this does not properly handle chunks that are > 64K under DOS */
1609 {
1610 png_bytep entry_start, buffer;
1611 png_sPLT_t new_palette;
1612 png_sPLT_entryp pp;
1613 png_uint_32 data_length;
1614 int entry_size, i;
1615 png_uint_32 skip = 0;
1616 png_uint_32 dl;
1617 png_size_t max_dl;
1618
1619 png_debug(1, "in png_handle_sPLT");
1620
1621 #ifdef PNG_USER_LIMITS_SUPPORTED
1622 if (png_ptr->user_chunk_cache_max != 0)
1623 {
1624 if (png_ptr->user_chunk_cache_max == 1)
1625 {
1626 png_crc_finish(png_ptr, length);
1627 return;
1628 }
1629
1630 if (--png_ptr->user_chunk_cache_max == 1)
1631 {
1632 png_warning(png_ptr, "No space in chunk cache for sPLT");
1633 png_crc_finish(png_ptr, length);
1634 return;
1635 }
1636 }
1637 #endif
1638
1639 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1640 png_chunk_error(png_ptr, "missing IHDR");
1641
1642 else if (png_ptr->mode & PNG_HAVE_IDAT)
1643 {
1644 png_crc_finish(png_ptr, length);
1645 png_chunk_benign_error(png_ptr, "out of place");
1646 return;
1647 }
1648
1649 #ifdef PNG_MAX_MALLOC_64K
1650 if (length > 65535U)
1651 {
1652 png_crc_finish(png_ptr, length);
1653 png_chunk_benign_error(png_ptr, "too large to fit in memory");
1654 return;
1655 }
1656 #endif
1657
1658 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
1659 if (buffer == NULL)
1660 {
1661 png_crc_finish(png_ptr, length);
1662 png_chunk_benign_error(png_ptr, "out of memory");
1663 return;
1664 }
1665
1666
1667 /* WARNING: this may break if size_t is less than 32 bits; it is assumed
1668 * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
1669 * potential breakage point if the types in pngconf.h aren't exactly right.
1670 */
1671 png_crc_read(png_ptr, buffer, length);
1672
1673 if (png_crc_finish(png_ptr, skip))
1674 return;
1675
1676 buffer[length] = 0;
1677
1678 for (entry_start = buffer; *entry_start; entry_start++)
1679 /* Empty loop to find end of name */ ;
1680
1681 ++entry_start;
1682
1683 /* A sample depth should follow the separator, and we should be on it */
1684 if (entry_start > buffer + length - 2)
1685 {
1686 png_warning(png_ptr, "malformed sPLT chunk");
1687 return;
1688 }
1689
1690 new_palette.depth = *entry_start++;
1691 entry_size = (new_palette.depth == 8 ? 6 : 10);
1692 /* This must fit in a png_uint_32 because it is derived from the original
1693 * chunk data length.
1694 */
1695 data_length = length - (png_uint_32)(entry_start - buffer);
1696
1697 /* Integrity-check the data length */
1698 if (data_length % entry_size)
1699 {
1700 png_warning(png_ptr, "sPLT chunk has bad length");
1701 return;
1702 }
1703
1704 dl = (png_int_32)(data_length / entry_size);
1705 max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
1706
1707 if (dl > max_dl)
1708 {
1709 png_warning(png_ptr, "sPLT chunk too long");
1710 return;
1711 }
1712
1713 new_palette.nentries = (png_int_32)(data_length / entry_size);
1714
1715 new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
1716 png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
1717
1718 if (new_palette.entries == NULL)
1719 {
1720 png_warning(png_ptr, "sPLT chunk requires too much memory");
1721 return;
1722 }
1723
1724 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1725 for (i = 0; i < new_palette.nentries; i++)
1726 {
1727 pp = new_palette.entries + i;
1728
1729 if (new_palette.depth == 8)
1730 {
1731 pp->red = *entry_start++;
1732 pp->green = *entry_start++;
1733 pp->blue = *entry_start++;
1734 pp->alpha = *entry_start++;
1735 }
1736
1737 else
1738 {
1739 pp->red = png_get_uint_16(entry_start); entry_start += 2;
1740 pp->green = png_get_uint_16(entry_start); entry_start += 2;
1741 pp->blue = png_get_uint_16(entry_start); entry_start += 2;
1742 pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
1743 }
1744
1745 pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
1746 }
1747 #else
1748 pp = new_palette.entries;
1749
1750 for (i = 0; i < new_palette.nentries; i++)
1751 {
1752
1753 if (new_palette.depth == 8)
1754 {
1755 pp[i].red = *entry_start++;
1756 pp[i].green = *entry_start++;
1757 pp[i].blue = *entry_start++;
1758 pp[i].alpha = *entry_start++;
1759 }
1760
1761 else
1762 {
1763 pp[i].red = png_get_uint_16(entry_start); entry_start += 2;
1764 pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
1765 pp[i].blue = png_get_uint_16(entry_start); entry_start += 2;
1766 pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
1767 }
1768
1769 pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
1770 }
1771 #endif
1772
1773 /* Discard all chunk data except the name and stash that */
1774 new_palette.name = (png_charp)buffer;
1775
1776 png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
1777
1778 png_free(png_ptr, new_palette.entries);
1779 }
1780 #endif /* PNG_READ_sPLT_SUPPORTED */
1781
1782 #ifdef PNG_READ_tRNS_SUPPORTED
1783 void /* PRIVATE */
png_handle_tRNS(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1784 png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1785 {
1786 png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
1787
1788 png_debug(1, "in png_handle_tRNS");
1789
1790 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1791 png_chunk_error(png_ptr, "missing IHDR");
1792
1793 else if (png_ptr->mode & PNG_HAVE_IDAT)
1794 {
1795 png_crc_finish(png_ptr, length);
1796 png_chunk_benign_error(png_ptr, "out of place");
1797 return;
1798 }
1799
1800 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
1801 {
1802 png_crc_finish(png_ptr, length);
1803 png_chunk_benign_error(png_ptr, "duplicate");
1804 return;
1805 }
1806
1807 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
1808 {
1809 png_byte buf[2];
1810
1811 if (length != 2)
1812 {
1813 png_crc_finish(png_ptr, length);
1814 png_chunk_benign_error(png_ptr, "invalid");
1815 return;
1816 }
1817
1818 png_crc_read(png_ptr, buf, 2);
1819 png_ptr->num_trans = 1;
1820 png_ptr->trans_color.gray = png_get_uint_16(buf);
1821 }
1822
1823 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
1824 {
1825 png_byte buf[6];
1826
1827 if (length != 6)
1828 {
1829 png_crc_finish(png_ptr, length);
1830 png_chunk_benign_error(png_ptr, "invalid");
1831 return;
1832 }
1833
1834 png_crc_read(png_ptr, buf, length);
1835 png_ptr->num_trans = 1;
1836 png_ptr->trans_color.red = png_get_uint_16(buf);
1837 png_ptr->trans_color.green = png_get_uint_16(buf + 2);
1838 png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
1839 }
1840
1841 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1842 {
1843 if (!(png_ptr->mode & PNG_HAVE_PLTE))
1844 {
1845 /* TODO: is this actually an error in the ISO spec? */
1846 png_crc_finish(png_ptr, length);
1847 png_chunk_benign_error(png_ptr, "out of place");
1848 return;
1849 }
1850
1851 if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH ||
1852 length == 0)
1853 {
1854 png_crc_finish(png_ptr, length);
1855 png_chunk_benign_error(png_ptr, "invalid");
1856 return;
1857 }
1858
1859 png_crc_read(png_ptr, readbuf, length);
1860 png_ptr->num_trans = (png_uint_16)length;
1861 }
1862
1863 else
1864 {
1865 png_crc_finish(png_ptr, length);
1866 png_chunk_benign_error(png_ptr, "invalid with alpha channel");
1867 return;
1868 }
1869
1870 if (png_crc_finish(png_ptr, 0))
1871 {
1872 png_ptr->num_trans = 0;
1873 return;
1874 }
1875
1876 /* TODO: this is a horrible side effect in the palette case because the
1877 * png_struct ends up with a pointer to the tRNS buffer owned by the
1878 * png_info. Fix this.
1879 */
1880 png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
1881 &(png_ptr->trans_color));
1882 }
1883 #endif
1884
1885 #ifdef PNG_READ_bKGD_SUPPORTED
1886 void /* PRIVATE */
png_handle_bKGD(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1887 png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1888 {
1889 unsigned int truelen;
1890 png_byte buf[6];
1891 png_color_16 background;
1892
1893 png_debug(1, "in png_handle_bKGD");
1894
1895 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1896 png_chunk_error(png_ptr, "missing IHDR");
1897
1898 else if ((png_ptr->mode & PNG_HAVE_IDAT) ||
1899 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
1900 !(png_ptr->mode & PNG_HAVE_PLTE)))
1901 {
1902 png_crc_finish(png_ptr, length);
1903 png_chunk_benign_error(png_ptr, "out of place");
1904 return;
1905 }
1906
1907 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
1908 {
1909 png_crc_finish(png_ptr, length);
1910 png_chunk_benign_error(png_ptr, "duplicate");
1911 return;
1912 }
1913
1914 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1915 truelen = 1;
1916
1917 else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
1918 truelen = 6;
1919
1920 else
1921 truelen = 2;
1922
1923 if (length != truelen)
1924 {
1925 png_crc_finish(png_ptr, length);
1926 png_chunk_benign_error(png_ptr, "invalid");
1927 return;
1928 }
1929
1930 png_crc_read(png_ptr, buf, truelen);
1931
1932 if (png_crc_finish(png_ptr, 0))
1933 return;
1934
1935 /* We convert the index value into RGB components so that we can allow
1936 * arbitrary RGB values for background when we have transparency, and
1937 * so it is easy to determine the RGB values of the background color
1938 * from the info_ptr struct.
1939 */
1940 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1941 {
1942 background.index = buf[0];
1943
1944 if (info_ptr && info_ptr->num_palette)
1945 {
1946 if (buf[0] >= info_ptr->num_palette)
1947 {
1948 png_chunk_benign_error(png_ptr, "invalid index");
1949 return;
1950 }
1951
1952 background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
1953 background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
1954 background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
1955 }
1956
1957 else
1958 background.red = background.green = background.blue = 0;
1959
1960 background.gray = 0;
1961 }
1962
1963 else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
1964 {
1965 background.index = 0;
1966 background.red =
1967 background.green =
1968 background.blue =
1969 background.gray = png_get_uint_16(buf);
1970 }
1971
1972 else
1973 {
1974 background.index = 0;
1975 background.red = png_get_uint_16(buf);
1976 background.green = png_get_uint_16(buf + 2);
1977 background.blue = png_get_uint_16(buf + 4);
1978 background.gray = 0;
1979 }
1980
1981 png_set_bKGD(png_ptr, info_ptr, &background);
1982 }
1983 #endif
1984
1985 #ifdef PNG_READ_hIST_SUPPORTED
1986 void /* PRIVATE */
png_handle_hIST(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1987 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1988 {
1989 unsigned int num, i;
1990 png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
1991
1992 png_debug(1, "in png_handle_hIST");
1993
1994 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1995 png_chunk_error(png_ptr, "missing IHDR");
1996
1997 else if ((png_ptr->mode & PNG_HAVE_IDAT) || !(png_ptr->mode & PNG_HAVE_PLTE))
1998 {
1999 png_crc_finish(png_ptr, length);
2000 png_chunk_benign_error(png_ptr, "out of place");
2001 return;
2002 }
2003
2004 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
2005 {
2006 png_crc_finish(png_ptr, length);
2007 png_chunk_benign_error(png_ptr, "duplicate");
2008 return;
2009 }
2010
2011 num = length / 2 ;
2012
2013 if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH)
2014 {
2015 png_crc_finish(png_ptr, length);
2016 png_chunk_benign_error(png_ptr, "invalid");
2017 return;
2018 }
2019
2020 for (i = 0; i < num; i++)
2021 {
2022 png_byte buf[2];
2023
2024 png_crc_read(png_ptr, buf, 2);
2025 readbuf[i] = png_get_uint_16(buf);
2026 }
2027
2028 if (png_crc_finish(png_ptr, 0))
2029 return;
2030
2031 png_set_hIST(png_ptr, info_ptr, readbuf);
2032 }
2033 #endif
2034
2035 #ifdef PNG_READ_pHYs_SUPPORTED
2036 void /* PRIVATE */
png_handle_pHYs(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2037 png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2038 {
2039 png_byte buf[9];
2040 png_uint_32 res_x, res_y;
2041 int unit_type;
2042
2043 png_debug(1, "in png_handle_pHYs");
2044
2045 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2046 png_chunk_error(png_ptr, "missing IHDR");
2047
2048 else if (png_ptr->mode & PNG_HAVE_IDAT)
2049 {
2050 png_crc_finish(png_ptr, length);
2051 png_chunk_benign_error(png_ptr, "out of place");
2052 return;
2053 }
2054
2055 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
2056 {
2057 png_crc_finish(png_ptr, length);
2058 png_chunk_benign_error(png_ptr, "duplicate");
2059 return;
2060 }
2061
2062 if (length != 9)
2063 {
2064 png_crc_finish(png_ptr, length);
2065 png_chunk_benign_error(png_ptr, "invalid");
2066 return;
2067 }
2068
2069 png_crc_read(png_ptr, buf, 9);
2070
2071 if (png_crc_finish(png_ptr, 0))
2072 return;
2073
2074 res_x = png_get_uint_32(buf);
2075 res_y = png_get_uint_32(buf + 4);
2076 unit_type = buf[8];
2077 png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
2078 }
2079 #endif
2080
2081 #ifdef PNG_READ_oFFs_SUPPORTED
2082 void /* PRIVATE */
png_handle_oFFs(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2083 png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2084 {
2085 png_byte buf[9];
2086 png_int_32 offset_x, offset_y;
2087 int unit_type;
2088
2089 png_debug(1, "in png_handle_oFFs");
2090
2091 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2092 png_chunk_error(png_ptr, "missing IHDR");
2093
2094 else if (png_ptr->mode & PNG_HAVE_IDAT)
2095 {
2096 png_crc_finish(png_ptr, length);
2097 png_chunk_benign_error(png_ptr, "out of place");
2098 return;
2099 }
2100
2101 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
2102 {
2103 png_crc_finish(png_ptr, length);
2104 png_chunk_benign_error(png_ptr, "duplicate");
2105 return;
2106 }
2107
2108 if (length != 9)
2109 {
2110 png_crc_finish(png_ptr, length);
2111 png_chunk_benign_error(png_ptr, "invalid");
2112 return;
2113 }
2114
2115 png_crc_read(png_ptr, buf, 9);
2116
2117 if (png_crc_finish(png_ptr, 0))
2118 return;
2119
2120 offset_x = png_get_int_32(buf);
2121 offset_y = png_get_int_32(buf + 4);
2122 unit_type = buf[8];
2123 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
2124 }
2125 #endif
2126
2127 #ifdef PNG_READ_pCAL_SUPPORTED
2128 /* Read the pCAL chunk (described in the PNG Extensions document) */
2129 void /* PRIVATE */
png_handle_pCAL(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2130 png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2131 {
2132 png_int_32 X0, X1;
2133 png_byte type, nparams;
2134 png_bytep buffer, buf, units, endptr;
2135 png_charpp params;
2136 int i;
2137
2138 png_debug(1, "in png_handle_pCAL");
2139
2140 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2141 png_chunk_error(png_ptr, "missing IHDR");
2142
2143 else if (png_ptr->mode & PNG_HAVE_IDAT)
2144 {
2145 png_crc_finish(png_ptr, length);
2146 png_chunk_benign_error(png_ptr, "out of place");
2147 return;
2148 }
2149
2150 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
2151 {
2152 png_crc_finish(png_ptr, length);
2153 png_chunk_benign_error(png_ptr, "duplicate");
2154 return;
2155 }
2156
2157 png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
2158 length + 1);
2159
2160 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2161
2162 if (buffer == NULL)
2163 {
2164 png_crc_finish(png_ptr, length);
2165 png_chunk_benign_error(png_ptr, "out of memory");
2166 return;
2167 }
2168
2169 png_crc_read(png_ptr, buffer, length);
2170
2171 if (png_crc_finish(png_ptr, 0))
2172 return;
2173
2174 buffer[length] = 0; /* Null terminate the last string */
2175
2176 png_debug(3, "Finding end of pCAL purpose string");
2177 for (buf = buffer; *buf; buf++)
2178 /* Empty loop */ ;
2179
2180 endptr = buffer + length;
2181
2182 /* We need to have at least 12 bytes after the purpose string
2183 * in order to get the parameter information.
2184 */
2185 if (endptr <= buf + 12)
2186 {
2187 png_chunk_benign_error(png_ptr, "invalid");
2188 return;
2189 }
2190
2191 png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
2192 X0 = png_get_int_32((png_bytep)buf+1);
2193 X1 = png_get_int_32((png_bytep)buf+5);
2194 type = buf[9];
2195 nparams = buf[10];
2196 units = buf + 11;
2197
2198 png_debug(3, "Checking pCAL equation type and number of parameters");
2199 /* Check that we have the right number of parameters for known
2200 * equation types.
2201 */
2202 if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
2203 (type == PNG_EQUATION_BASE_E && nparams != 3) ||
2204 (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
2205 (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
2206 {
2207 png_chunk_benign_error(png_ptr, "invalid parameter count");
2208 return;
2209 }
2210
2211 else if (type >= PNG_EQUATION_LAST)
2212 {
2213 png_chunk_benign_error(png_ptr, "unrecognized equation type");
2214 }
2215
2216 for (buf = units; *buf; buf++)
2217 /* Empty loop to move past the units string. */ ;
2218
2219 png_debug(3, "Allocating pCAL parameters array");
2220
2221 params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
2222 nparams * (sizeof (png_charp))));
2223
2224 if (params == NULL)
2225 {
2226 png_chunk_benign_error(png_ptr, "out of memory");
2227 return;
2228 }
2229
2230 /* Get pointers to the start of each parameter string. */
2231 for (i = 0; i < nparams; i++)
2232 {
2233 buf++; /* Skip the null string terminator from previous parameter. */
2234
2235 png_debug1(3, "Reading pCAL parameter %d", i);
2236
2237 for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
2238 /* Empty loop to move past each parameter string */ ;
2239
2240 /* Make sure we haven't run out of data yet */
2241 if (buf > endptr)
2242 {
2243 png_free(png_ptr, params);
2244 png_chunk_benign_error(png_ptr, "invalid data");
2245 return;
2246 }
2247 }
2248
2249 png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
2250 (png_charp)units, params);
2251
2252 png_free(png_ptr, params);
2253 }
2254 #endif
2255
2256 #ifdef PNG_READ_sCAL_SUPPORTED
2257 /* Read the sCAL chunk */
2258 void /* PRIVATE */
png_handle_sCAL(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2259 png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2260 {
2261 png_bytep buffer;
2262 png_size_t i;
2263 int state;
2264
2265 png_debug(1, "in png_handle_sCAL");
2266
2267 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2268 png_chunk_error(png_ptr, "missing IHDR");
2269
2270 else if (png_ptr->mode & PNG_HAVE_IDAT)
2271 {
2272 png_crc_finish(png_ptr, length);
2273 png_chunk_benign_error(png_ptr, "out of place");
2274 return;
2275 }
2276
2277 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
2278 {
2279 png_crc_finish(png_ptr, length);
2280 png_chunk_benign_error(png_ptr, "duplicate");
2281 return;
2282 }
2283
2284 /* Need unit type, width, \0, height: minimum 4 bytes */
2285 else if (length < 4)
2286 {
2287 png_crc_finish(png_ptr, length);
2288 png_chunk_benign_error(png_ptr, "invalid");
2289 return;
2290 }
2291
2292 png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
2293 length + 1);
2294
2295 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2296
2297 if (buffer == NULL)
2298 {
2299 png_chunk_benign_error(png_ptr, "out of memory");
2300 png_crc_finish(png_ptr, length);
2301 return;
2302 }
2303
2304 png_crc_read(png_ptr, buffer, length);
2305 buffer[length] = 0; /* Null terminate the last string */
2306
2307 if (png_crc_finish(png_ptr, 0))
2308 return;
2309
2310 /* Validate the unit. */
2311 if (buffer[0] != 1 && buffer[0] != 2)
2312 {
2313 png_chunk_benign_error(png_ptr, "invalid unit");
2314 return;
2315 }
2316
2317 /* Validate the ASCII numbers, need two ASCII numbers separated by
2318 * a '\0' and they need to fit exactly in the chunk data.
2319 */
2320 i = 1;
2321 state = 0;
2322
2323 if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
2324 i >= length || buffer[i++] != 0)
2325 png_chunk_benign_error(png_ptr, "bad width format");
2326
2327 else if (!PNG_FP_IS_POSITIVE(state))
2328 png_chunk_benign_error(png_ptr, "non-positive width");
2329
2330 else
2331 {
2332 png_size_t heighti = i;
2333
2334 state = 0;
2335 if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
2336 i != length)
2337 png_chunk_benign_error(png_ptr, "bad height format");
2338
2339 else if (!PNG_FP_IS_POSITIVE(state))
2340 png_chunk_benign_error(png_ptr, "non-positive height");
2341
2342 else
2343 /* This is the (only) success case. */
2344 png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
2345 (png_charp)buffer+1, (png_charp)buffer+heighti);
2346 }
2347 }
2348 #endif
2349
2350 #ifdef PNG_READ_tIME_SUPPORTED
2351 void /* PRIVATE */
png_handle_tIME(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2352 png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2353 {
2354 png_byte buf[7];
2355 png_time mod_time;
2356
2357 png_debug(1, "in png_handle_tIME");
2358
2359 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2360 png_chunk_error(png_ptr, "missing IHDR");
2361
2362 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
2363 {
2364 png_crc_finish(png_ptr, length);
2365 png_chunk_benign_error(png_ptr, "duplicate");
2366 return;
2367 }
2368
2369 if (png_ptr->mode & PNG_HAVE_IDAT)
2370 png_ptr->mode |= PNG_AFTER_IDAT;
2371
2372 if (length != 7)
2373 {
2374 png_crc_finish(png_ptr, length);
2375 png_chunk_benign_error(png_ptr, "invalid");
2376 return;
2377 }
2378
2379 png_crc_read(png_ptr, buf, 7);
2380
2381 if (png_crc_finish(png_ptr, 0))
2382 return;
2383
2384 mod_time.second = buf[6];
2385 mod_time.minute = buf[5];
2386 mod_time.hour = buf[4];
2387 mod_time.day = buf[3];
2388 mod_time.month = buf[2];
2389 mod_time.year = png_get_uint_16(buf);
2390
2391 png_set_tIME(png_ptr, info_ptr, &mod_time);
2392 }
2393 #endif
2394
2395 #ifdef PNG_READ_tEXt_SUPPORTED
2396 /* Note: this does not properly handle chunks that are > 64K under DOS */
2397 void /* PRIVATE */
png_handle_tEXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2398 png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2399 {
2400 png_text text_info;
2401 png_bytep buffer;
2402 png_charp key;
2403 png_charp text;
2404 png_uint_32 skip = 0;
2405
2406 png_debug(1, "in png_handle_tEXt");
2407
2408 #ifdef PNG_USER_LIMITS_SUPPORTED
2409 if (png_ptr->user_chunk_cache_max != 0)
2410 {
2411 if (png_ptr->user_chunk_cache_max == 1)
2412 {
2413 png_crc_finish(png_ptr, length);
2414 return;
2415 }
2416
2417 if (--png_ptr->user_chunk_cache_max == 1)
2418 {
2419 png_crc_finish(png_ptr, length);
2420 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2421 return;
2422 }
2423 }
2424 #endif
2425
2426 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2427 png_chunk_error(png_ptr, "missing IHDR");
2428
2429 if (png_ptr->mode & PNG_HAVE_IDAT)
2430 png_ptr->mode |= PNG_AFTER_IDAT;
2431
2432 #ifdef PNG_MAX_MALLOC_64K
2433 if (length > 65535U)
2434 {
2435 png_crc_finish(png_ptr, length);
2436 png_chunk_benign_error(png_ptr, "too large to fit in memory");
2437 return;
2438 }
2439 #endif
2440
2441 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2442
2443 if (buffer == NULL)
2444 {
2445 png_chunk_benign_error(png_ptr, "out of memory");
2446 return;
2447 }
2448
2449 png_crc_read(png_ptr, buffer, length);
2450
2451 if (png_crc_finish(png_ptr, skip))
2452 return;
2453
2454 key = (png_charp)buffer;
2455 key[length] = 0;
2456
2457 for (text = key; *text; text++)
2458 /* Empty loop to find end of key */ ;
2459
2460 if (text != key + length)
2461 text++;
2462
2463 text_info.compression = PNG_TEXT_COMPRESSION_NONE;
2464 text_info.key = key;
2465 text_info.lang = NULL;
2466 text_info.lang_key = NULL;
2467 text_info.itxt_length = 0;
2468 text_info.text = text;
2469 text_info.text_length = strlen(text);
2470
2471 if (png_set_text_2(png_ptr, info_ptr, &text_info, 1))
2472 png_warning(png_ptr, "Insufficient memory to process text chunk");
2473 }
2474 #endif
2475
2476 #ifdef PNG_READ_zTXt_SUPPORTED
2477 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2478 void /* PRIVATE */
png_handle_zTXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2479 png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2480 {
2481 png_const_charp errmsg = NULL;
2482 png_bytep buffer;
2483 png_uint_32 keyword_length;
2484
2485 png_debug(1, "in png_handle_zTXt");
2486
2487 #ifdef PNG_USER_LIMITS_SUPPORTED
2488 if (png_ptr->user_chunk_cache_max != 0)
2489 {
2490 if (png_ptr->user_chunk_cache_max == 1)
2491 {
2492 png_crc_finish(png_ptr, length);
2493 return;
2494 }
2495
2496 if (--png_ptr->user_chunk_cache_max == 1)
2497 {
2498 png_crc_finish(png_ptr, length);
2499 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2500 return;
2501 }
2502 }
2503 #endif
2504
2505 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2506 png_chunk_error(png_ptr, "missing IHDR");
2507
2508 if (png_ptr->mode & PNG_HAVE_IDAT)
2509 png_ptr->mode |= PNG_AFTER_IDAT;
2510
2511 buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
2512
2513 if (buffer == NULL)
2514 {
2515 png_crc_finish(png_ptr, length);
2516 png_chunk_benign_error(png_ptr, "out of memory");
2517 return;
2518 }
2519
2520 png_crc_read(png_ptr, buffer, length);
2521
2522 if (png_crc_finish(png_ptr, 0))
2523 return;
2524
2525 /* TODO: also check that the keyword contents match the spec! */
2526 for (keyword_length = 0;
2527 keyword_length < length && buffer[keyword_length] != 0;
2528 ++keyword_length)
2529 /* Empty loop to find end of name */ ;
2530
2531 if (keyword_length > 79 || keyword_length < 1)
2532 errmsg = "bad keyword";
2533
2534 /* zTXt must have some LZ data after the keyword, although it may expand to
2535 * zero bytes; we need a '\0' at the end of the keyword, the compression type
2536 * then the LZ data:
2537 */
2538 else if (keyword_length + 3 > length)
2539 errmsg = "truncated";
2540
2541 else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
2542 errmsg = "unknown compression type";
2543
2544 else
2545 {
2546 png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
2547
2548 /* TODO: at present png_decompress_chunk imposes a single application
2549 * level memory limit, this should be split to different values for iCCP
2550 * and text chunks.
2551 */
2552 if (png_decompress_chunk(png_ptr, length, keyword_length+2,
2553 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2554 {
2555 png_text text;
2556
2557 /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
2558 * for the extra compression type byte and the fact that it isn't
2559 * necessarily '\0' terminated.
2560 */
2561 buffer = png_ptr->read_buffer;
2562 buffer[uncompressed_length+(keyword_length+2)] = 0;
2563
2564 text.compression = PNG_TEXT_COMPRESSION_zTXt;
2565 text.key = (png_charp)buffer;
2566 text.text = (png_charp)(buffer + keyword_length+2);
2567 text.text_length = uncompressed_length;
2568 text.itxt_length = 0;
2569 text.lang = NULL;
2570 text.lang_key = NULL;
2571
2572 if (png_set_text_2(png_ptr, info_ptr, &text, 1))
2573 errmsg = "insufficient memory";
2574 }
2575
2576 else
2577 errmsg = png_ptr->zstream.msg;
2578 }
2579
2580 if (errmsg != NULL)
2581 png_chunk_benign_error(png_ptr, errmsg);
2582 }
2583 #endif
2584
2585 #ifdef PNG_READ_iTXt_SUPPORTED
2586 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2587 void /* PRIVATE */
png_handle_iTXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2588 png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2589 {
2590 png_const_charp errmsg = NULL;
2591 png_bytep buffer;
2592 png_uint_32 prefix_length;
2593
2594 png_debug(1, "in png_handle_iTXt");
2595
2596 #ifdef PNG_USER_LIMITS_SUPPORTED
2597 if (png_ptr->user_chunk_cache_max != 0)
2598 {
2599 if (png_ptr->user_chunk_cache_max == 1)
2600 {
2601 png_crc_finish(png_ptr, length);
2602 return;
2603 }
2604
2605 if (--png_ptr->user_chunk_cache_max == 1)
2606 {
2607 png_crc_finish(png_ptr, length);
2608 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2609 return;
2610 }
2611 }
2612 #endif
2613
2614 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2615 png_chunk_error(png_ptr, "missing IHDR");
2616
2617 if (png_ptr->mode & PNG_HAVE_IDAT)
2618 png_ptr->mode |= PNG_AFTER_IDAT;
2619
2620 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2621
2622 if (buffer == NULL)
2623 {
2624 png_crc_finish(png_ptr, length);
2625 png_chunk_benign_error(png_ptr, "out of memory");
2626 return;
2627 }
2628
2629 png_crc_read(png_ptr, buffer, length);
2630
2631 if (png_crc_finish(png_ptr, 0))
2632 return;
2633
2634 /* First the keyword. */
2635 for (prefix_length=0;
2636 prefix_length < length && buffer[prefix_length] != 0;
2637 ++prefix_length)
2638 /* Empty loop */ ;
2639
2640 /* Perform a basic check on the keyword length here. */
2641 if (prefix_length > 79 || prefix_length < 1)
2642 errmsg = "bad keyword";
2643
2644 /* Expect keyword, compression flag, compression type, language, translated
2645 * keyword (both may be empty but are 0 terminated) then the text, which may
2646 * be empty.
2647 */
2648 else if (prefix_length + 5 > length)
2649 errmsg = "truncated";
2650
2651 else if (buffer[prefix_length+1] == 0 ||
2652 (buffer[prefix_length+1] == 1 &&
2653 buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
2654 {
2655 int compressed = buffer[prefix_length+1] != 0;
2656 png_uint_32 language_offset, translated_keyword_offset;
2657 png_alloc_size_t uncompressed_length = 0;
2658
2659 /* Now the language tag */
2660 prefix_length += 3;
2661 language_offset = prefix_length;
2662
2663 for (; prefix_length < length && buffer[prefix_length] != 0;
2664 ++prefix_length)
2665 /* Empty loop */ ;
2666
2667 /* WARNING: the length may be invalid here, this is checked below. */
2668 translated_keyword_offset = ++prefix_length;
2669
2670 for (; prefix_length < length && buffer[prefix_length] != 0;
2671 ++prefix_length)
2672 /* Empty loop */ ;
2673
2674 /* prefix_length should now be at the trailing '\0' of the translated
2675 * keyword, but it may already be over the end. None of this arithmetic
2676 * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
2677 * systems the available allocaton may overflow.
2678 */
2679 ++prefix_length;
2680
2681 if (!compressed && prefix_length <= length)
2682 uncompressed_length = length - prefix_length;
2683
2684 else if (compressed && prefix_length < length)
2685 {
2686 uncompressed_length = PNG_SIZE_MAX;
2687
2688 /* TODO: at present png_decompress_chunk imposes a single application
2689 * level memory limit, this should be split to different values for
2690 * iCCP and text chunks.
2691 */
2692 if (png_decompress_chunk(png_ptr, length, prefix_length,
2693 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2694 buffer = png_ptr->read_buffer;
2695
2696 else
2697 errmsg = png_ptr->zstream.msg;
2698 }
2699
2700 else
2701 errmsg = "truncated";
2702
2703 if (errmsg == NULL)
2704 {
2705 png_text text;
2706
2707 buffer[uncompressed_length+prefix_length] = 0;
2708
2709 if (compressed)
2710 text.compression = PNG_ITXT_COMPRESSION_NONE;
2711
2712 else
2713 text.compression = PNG_ITXT_COMPRESSION_zTXt;
2714
2715 text.key = (png_charp)buffer;
2716 text.lang = (png_charp)buffer + language_offset;
2717 text.lang_key = (png_charp)buffer + translated_keyword_offset;
2718 text.text = (png_charp)buffer + prefix_length;
2719 text.text_length = 0;
2720 text.itxt_length = uncompressed_length;
2721
2722 if (png_set_text_2(png_ptr, info_ptr, &text, 1))
2723 errmsg = "insufficient memory";
2724 }
2725 }
2726
2727 else
2728 errmsg = "bad compression info";
2729
2730 if (errmsg != NULL)
2731 png_chunk_benign_error(png_ptr, errmsg);
2732 }
2733 #endif
2734
2735 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2736 /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
2737 static int
png_cache_unknown_chunk(png_structrp png_ptr,png_uint_32 length)2738 png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
2739 {
2740 png_alloc_size_t limit = PNG_SIZE_MAX;
2741
2742 if (png_ptr->unknown_chunk.data != NULL)
2743 {
2744 png_free(png_ptr, png_ptr->unknown_chunk.data);
2745 png_ptr->unknown_chunk.data = NULL;
2746 }
2747
2748 # ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
2749 if (png_ptr->user_chunk_malloc_max > 0 &&
2750 png_ptr->user_chunk_malloc_max < limit)
2751 limit = png_ptr->user_chunk_malloc_max;
2752
2753 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
2754 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
2755 limit = PNG_USER_CHUNK_MALLOC_MAX;
2756 # endif
2757
2758 if (length <= limit)
2759 {
2760 PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
2761 /* The following is safe because of the PNG_SIZE_MAX init above */
2762 png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
2763 /* 'mode' is a flag array, only the bottom four bits matter here */
2764 png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
2765
2766 if (length == 0)
2767 png_ptr->unknown_chunk.data = NULL;
2768
2769 else
2770 {
2771 /* Do a 'warn' here - it is handled below. */
2772 png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
2773 png_malloc_warn(png_ptr, length));
2774 }
2775 }
2776
2777 if (png_ptr->unknown_chunk.data == NULL && length > 0)
2778 {
2779 /* This is benign because we clean up correctly */
2780 png_crc_finish(png_ptr, length);
2781 png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
2782 return 0;
2783 }
2784
2785 else
2786 {
2787 if (length > 0)
2788 png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
2789 png_crc_finish(png_ptr, 0);
2790 return 1;
2791 }
2792 }
2793 #endif /* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2794
2795 /* Handle an unknown, or known but disabled, chunk */
2796 void /* PRIVATE */
png_handle_unknown(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length,int keep)2797 png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
2798 png_uint_32 length, int keep)
2799 {
2800 int handled = 0; /* the chunk was handled */
2801
2802 png_debug(1, "in png_handle_unknown");
2803
2804 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2805 /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
2806 * the bug which meant that setting a non-default behavior for a specific
2807 * chunk would be ignored (the default was always used unless a user
2808 * callback was installed).
2809 *
2810 * 'keep' is the value from the png_chunk_unknown_handling, the setting for
2811 * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
2812 * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
2813 * This is just an optimization to avoid multiple calls to the lookup
2814 * function.
2815 */
2816 # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
2817 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2818 keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
2819 # endif
2820 # endif
2821
2822 /* One of the following methods will read the chunk or skip it (at least one
2823 * of these is always defined because this is the only way to switch on
2824 * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
2825 */
2826 # ifdef PNG_READ_USER_CHUNKS_SUPPORTED
2827 /* The user callback takes precedence over the chunk keep value, but the
2828 * keep value is still required to validate a save of a critical chunk.
2829 */
2830 if (png_ptr->read_user_chunk_fn != NULL)
2831 {
2832 if (png_cache_unknown_chunk(png_ptr, length))
2833 {
2834 /* Callback to user unknown chunk handler */
2835 int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
2836 &png_ptr->unknown_chunk);
2837
2838 /* ret is:
2839 * negative: An error occured, png_chunk_error will be called.
2840 * zero: The chunk was not handled, the chunk will be discarded
2841 * unless png_set_keep_unknown_chunks has been used to set
2842 * a 'keep' behavior for this particular chunk, in which
2843 * case that will be used. A critical chunk will cause an
2844 * error at this point unless it is to be saved.
2845 * positive: The chunk was handled, libpng will ignore/discard it.
2846 */
2847 if (ret < 0)
2848 png_chunk_error(png_ptr, "error in user chunk");
2849
2850 else if (ret == 0)
2851 {
2852 /* If the keep value is 'default' or 'never' override it, but
2853 * still error out on critical chunks unless the keep value is
2854 * 'always' While this is weird it is the behavior in 1.4.12.
2855 * A possible improvement would be to obey the value set for the
2856 * chunk, but this would be an API change that would probably
2857 * damage some applications.
2858 *
2859 * The png_app_warning below catches the case that matters, where
2860 * the application has not set specific save or ignore for this
2861 * chunk or global save or ignore.
2862 */
2863 if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
2864 {
2865 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2866 if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
2867 {
2868 png_chunk_warning(png_ptr, "Saving unknown chunk:");
2869 png_app_warning(png_ptr,
2870 "forcing save of an unhandled chunk;"
2871 " please call png_set_keep_unknown_chunks");
2872 /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
2873 }
2874 # endif
2875 keep = PNG_HANDLE_CHUNK_IF_SAFE;
2876 }
2877 }
2878
2879 else /* chunk was handled */
2880 {
2881 handled = 1;
2882 /* Critical chunks can be safely discarded at this point. */
2883 keep = PNG_HANDLE_CHUNK_NEVER;
2884 }
2885 }
2886
2887 else
2888 keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
2889 }
2890
2891 else
2892 /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
2893 # endif /* PNG_READ_USER_CHUNKS_SUPPORTED */
2894
2895 # ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
2896 {
2897 /* keep is currently just the per-chunk setting, if there was no
2898 * setting change it to the global default now (not that this may
2899 * still be AS_DEFAULT) then obtain the cache of the chunk if required,
2900 * if not simply skip the chunk.
2901 */
2902 if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
2903 keep = png_ptr->unknown_default;
2904
2905 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
2906 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
2907 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
2908 {
2909 if (!png_cache_unknown_chunk(png_ptr, length))
2910 keep = PNG_HANDLE_CHUNK_NEVER;
2911 }
2912
2913 else
2914 png_crc_finish(png_ptr, length);
2915 }
2916 # else
2917 # ifndef PNG_READ_USER_CHUNKS_SUPPORTED
2918 # error no method to support READ_UNKNOWN_CHUNKS
2919 # endif
2920
2921 {
2922 /* If here there is no read callback pointer set and no support is
2923 * compiled in to just save the unknown chunks, so simply skip this
2924 * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then
2925 * the app has erroneously asked for unknown chunk saving when there
2926 * is no support.
2927 */
2928 if (keep > PNG_HANDLE_CHUNK_NEVER)
2929 png_app_error(png_ptr, "no unknown chunk support available");
2930
2931 png_crc_finish(png_ptr, length);
2932 }
2933 # endif
2934
2935 # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2936 /* Now store the chunk in the chunk list if appropriate, and if the limits
2937 * permit it.
2938 */
2939 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
2940 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
2941 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
2942 {
2943 # ifdef PNG_USER_LIMITS_SUPPORTED
2944 switch (png_ptr->user_chunk_cache_max)
2945 {
2946 case 2:
2947 png_ptr->user_chunk_cache_max = 1;
2948 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2949 /* FALL THROUGH */
2950 case 1:
2951 /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
2952 * chunk being skipped, now there will be a hard error below.
2953 */
2954 break;
2955
2956 default: /* not at limit */
2957 --(png_ptr->user_chunk_cache_max);
2958 /* FALL THROUGH */
2959 case 0: /* no limit */
2960 # endif /* PNG_USER_LIMITS_SUPPORTED */
2961 /* Here when the limit isn't reached or when limits are compiled
2962 * out; store the chunk.
2963 */
2964 png_set_unknown_chunks(png_ptr, info_ptr,
2965 &png_ptr->unknown_chunk, 1);
2966 handled = 1;
2967 # ifdef PNG_USER_LIMITS_SUPPORTED
2968 break;
2969 }
2970 # endif
2971 }
2972 # else /* no store support: the chunk must be handled by the user callback */
2973 PNG_UNUSED(info_ptr)
2974 # endif
2975
2976 /* Regardless of the error handling below the cached data (if any) can be
2977 * freed now. Notice that the data is not freed if there is a png_error, but
2978 * it will be freed by destroy_read_struct.
2979 */
2980 if (png_ptr->unknown_chunk.data != NULL)
2981 png_free(png_ptr, png_ptr->unknown_chunk.data);
2982 png_ptr->unknown_chunk.data = NULL;
2983
2984 #else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2985 /* There is no support to read an unknown chunk, so just skip it. */
2986 png_crc_finish(png_ptr, length);
2987 PNG_UNUSED(info_ptr)
2988 PNG_UNUSED(keep)
2989 #endif /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2990
2991 /* Check for unhandled critical chunks */
2992 if (!handled && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
2993 png_chunk_error(png_ptr, "unhandled critical chunk");
2994 }
2995
2996 /* This function is called to verify that a chunk name is valid.
2997 * This function can't have the "critical chunk check" incorporated
2998 * into it, since in the future we will need to be able to call user
2999 * functions to handle unknown critical chunks after we check that
3000 * the chunk name itself is valid.
3001 */
3002
3003 /* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
3004 *
3005 * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
3006 */
3007
3008 void /* PRIVATE */
png_check_chunk_name(png_structrp png_ptr,png_uint_32 chunk_name)3009 png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
3010 {
3011 int i;
3012
3013 png_debug(1, "in png_check_chunk_name");
3014
3015 for (i=1; i<=4; ++i)
3016 {
3017 int c = chunk_name & 0xff;
3018
3019 if (c < 65 || c > 122 || (c > 90 && c < 97))
3020 png_chunk_error(png_ptr, "invalid chunk type");
3021
3022 chunk_name >>= 8;
3023 }
3024 }
3025
3026 /* Combines the row recently read in with the existing pixels in the row. This
3027 * routine takes care of alpha and transparency if requested. This routine also
3028 * handles the two methods of progressive display of interlaced images,
3029 * depending on the 'display' value; if 'display' is true then the whole row
3030 * (dp) is filled from the start by replicating the available pixels. If
3031 * 'display' is false only those pixels present in the pass are filled in.
3032 */
3033 void /* PRIVATE */
png_combine_row(png_const_structrp png_ptr,png_bytep dp,int display)3034 png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
3035 {
3036 unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
3037 png_const_bytep sp = png_ptr->row_buf + 1;
3038 png_alloc_size_t row_width = png_ptr->width;
3039 unsigned int pass = png_ptr->pass;
3040 png_bytep end_ptr = 0;
3041 png_byte end_byte = 0;
3042 unsigned int end_mask;
3043
3044 png_debug(1, "in png_combine_row");
3045
3046 /* Added in 1.5.6: it should not be possible to enter this routine until at
3047 * least one row has been read from the PNG data and transformed.
3048 */
3049 if (pixel_depth == 0)
3050 png_error(png_ptr, "internal row logic error");
3051
3052 /* Added in 1.5.4: the pixel depth should match the information returned by
3053 * any call to png_read_update_info at this point. Do not continue if we got
3054 * this wrong.
3055 */
3056 if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
3057 PNG_ROWBYTES(pixel_depth, row_width))
3058 png_error(png_ptr, "internal row size calculation error");
3059
3060 /* Don't expect this to ever happen: */
3061 if (row_width == 0)
3062 png_error(png_ptr, "internal row width error");
3063
3064 /* Preserve the last byte in cases where only part of it will be overwritten,
3065 * the multiply below may overflow, we don't care because ANSI-C guarantees
3066 * we get the low bits.
3067 */
3068 end_mask = (pixel_depth * row_width) & 7;
3069 if (end_mask != 0)
3070 {
3071 /* end_ptr == NULL is a flag to say do nothing */
3072 end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
3073 end_byte = *end_ptr;
3074 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3075 if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
3076 end_mask = 0xff << end_mask;
3077
3078 else /* big-endian byte */
3079 # endif
3080 end_mask = 0xff >> end_mask;
3081 /* end_mask is now the bits to *keep* from the destination row */
3082 }
3083
3084 /* For non-interlaced images this reduces to a memcpy(). A memcpy()
3085 * will also happen if interlacing isn't supported or if the application
3086 * does not call png_set_interlace_handling(). In the latter cases the
3087 * caller just gets a sequence of the unexpanded rows from each interlace
3088 * pass.
3089 */
3090 #ifdef PNG_READ_INTERLACING_SUPPORTED
3091 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
3092 pass < 6 && (display == 0 ||
3093 /* The following copies everything for 'display' on passes 0, 2 and 4. */
3094 (display == 1 && (pass & 1) != 0)))
3095 {
3096 /* Narrow images may have no bits in a pass; the caller should handle
3097 * this, but this test is cheap:
3098 */
3099 if (row_width <= PNG_PASS_START_COL(pass))
3100 return;
3101
3102 if (pixel_depth < 8)
3103 {
3104 /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
3105 * into 32 bits, then a single loop over the bytes using the four byte
3106 * values in the 32-bit mask can be used. For the 'display' option the
3107 * expanded mask may also not require any masking within a byte. To
3108 * make this work the PACKSWAP option must be taken into account - it
3109 * simply requires the pixels to be reversed in each byte.
3110 *
3111 * The 'regular' case requires a mask for each of the first 6 passes,
3112 * the 'display' case does a copy for the even passes in the range
3113 * 0..6. This has already been handled in the test above.
3114 *
3115 * The masks are arranged as four bytes with the first byte to use in
3116 * the lowest bits (little-endian) regardless of the order (PACKSWAP or
3117 * not) of the pixels in each byte.
3118 *
3119 * NOTE: the whole of this logic depends on the caller of this function
3120 * only calling it on rows appropriate to the pass. This function only
3121 * understands the 'x' logic; the 'y' logic is handled by the caller.
3122 *
3123 * The following defines allow generation of compile time constant bit
3124 * masks for each pixel depth and each possibility of swapped or not
3125 * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index,
3126 * is in the range 0..7; and the result is 1 if the pixel is to be
3127 * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B'
3128 * for the block method.
3129 *
3130 * With some compilers a compile time expression of the general form:
3131 *
3132 * (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
3133 *
3134 * Produces warnings with values of 'shift' in the range 33 to 63
3135 * because the right hand side of the ?: expression is evaluated by
3136 * the compiler even though it isn't used. Microsoft Visual C (various
3137 * versions) and the Intel C compiler are known to do this. To avoid
3138 * this the following macros are used in 1.5.6. This is a temporary
3139 * solution to avoid destabilizing the code during the release process.
3140 */
3141 # if PNG_USE_COMPILE_TIME_MASKS
3142 # define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
3143 # define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
3144 # else
3145 # define PNG_LSR(x,s) ((x)>>(s))
3146 # define PNG_LSL(x,s) ((x)<<(s))
3147 # endif
3148 # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
3149 PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
3150 # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
3151 PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
3152
3153 /* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is
3154 * little endian - the first pixel is at bit 0 - however the extra
3155 * parameter 's' can be set to cause the mask position to be swapped
3156 * within each byte, to match the PNG format. This is done by XOR of
3157 * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
3158 */
3159 # define PIXEL_MASK(p,x,d,s) \
3160 (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
3161
3162 /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
3163 */
3164 # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3165 # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3166
3167 /* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp
3168 * cases the result needs replicating, for the 4-bpp case the above
3169 * generates a full 32 bits.
3170 */
3171 # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
3172
3173 # define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
3174 S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
3175 S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
3176
3177 # define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
3178 B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
3179 B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
3180
3181 #if PNG_USE_COMPILE_TIME_MASKS
3182 /* Utility macros to construct all the masks for a depth/swap
3183 * combination. The 's' parameter says whether the format is PNG
3184 * (big endian bytes) or not. Only the three odd-numbered passes are
3185 * required for the display/block algorithm.
3186 */
3187 # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
3188 S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
3189
3190 # define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }
3191
3192 # define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
3193
3194 /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
3195 * then pass:
3196 */
3197 static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
3198 {
3199 /* Little-endian byte masks for PACKSWAP */
3200 { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
3201 /* Normal (big-endian byte) masks - PNG format */
3202 { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
3203 };
3204
3205 /* display_mask has only three entries for the odd passes, so index by
3206 * pass>>1.
3207 */
3208 static PNG_CONST png_uint_32 display_mask[2][3][3] =
3209 {
3210 /* Little-endian byte masks for PACKSWAP */
3211 { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
3212 /* Normal (big-endian byte) masks - PNG format */
3213 { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
3214 };
3215
3216 # define MASK(pass,depth,display,png)\
3217 ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
3218 row_mask[png][DEPTH_INDEX(depth)][pass])
3219
3220 #else /* !PNG_USE_COMPILE_TIME_MASKS */
3221 /* This is the runtime alternative: it seems unlikely that this will
3222 * ever be either smaller or faster than the compile time approach.
3223 */
3224 # define MASK(pass,depth,display,png)\
3225 ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
3226 #endif /* !PNG_USE_COMPILE_TIME_MASKS */
3227
3228 /* Use the appropriate mask to copy the required bits. In some cases
3229 * the byte mask will be 0 or 0xff, optimize these cases. row_width is
3230 * the number of pixels, but the code copies bytes, so it is necessary
3231 * to special case the end.
3232 */
3233 png_uint_32 pixels_per_byte = 8 / pixel_depth;
3234 png_uint_32 mask;
3235
3236 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3237 if (png_ptr->transformations & PNG_PACKSWAP)
3238 mask = MASK(pass, pixel_depth, display, 0);
3239
3240 else
3241 # endif
3242 mask = MASK(pass, pixel_depth, display, 1);
3243
3244 for (;;)
3245 {
3246 png_uint_32 m;
3247
3248 /* It doesn't matter in the following if png_uint_32 has more than
3249 * 32 bits because the high bits always match those in m<<24; it is,
3250 * however, essential to use OR here, not +, because of this.
3251 */
3252 m = mask;
3253 mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
3254 m &= 0xff;
3255
3256 if (m != 0) /* something to copy */
3257 {
3258 if (m != 0xff)
3259 *dp = (png_byte)((*dp & ~m) | (*sp & m));
3260 else
3261 *dp = *sp;
3262 }
3263
3264 /* NOTE: this may overwrite the last byte with garbage if the image
3265 * is not an exact number of bytes wide; libpng has always done
3266 * this.
3267 */
3268 if (row_width <= pixels_per_byte)
3269 break; /* May need to restore part of the last byte */
3270
3271 row_width -= pixels_per_byte;
3272 ++dp;
3273 ++sp;
3274 }
3275 }
3276
3277 else /* pixel_depth >= 8 */
3278 {
3279 unsigned int bytes_to_copy, bytes_to_jump;
3280
3281 /* Validate the depth - it must be a multiple of 8 */
3282 if (pixel_depth & 7)
3283 png_error(png_ptr, "invalid user transform pixel depth");
3284
3285 pixel_depth >>= 3; /* now in bytes */
3286 row_width *= pixel_depth;
3287
3288 /* Regardless of pass number the Adam 7 interlace always results in a
3289 * fixed number of pixels to copy then to skip. There may be a
3290 * different number of pixels to skip at the start though.
3291 */
3292 {
3293 unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
3294
3295 row_width -= offset;
3296 dp += offset;
3297 sp += offset;
3298 }
3299
3300 /* Work out the bytes to copy. */
3301 if (display)
3302 {
3303 /* When doing the 'block' algorithm the pixel in the pass gets
3304 * replicated to adjacent pixels. This is why the even (0,2,4,6)
3305 * passes are skipped above - the entire expanded row is copied.
3306 */
3307 bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
3308
3309 /* But don't allow this number to exceed the actual row width. */
3310 if (bytes_to_copy > row_width)
3311 bytes_to_copy = (unsigned int)/*SAFE*/row_width;
3312 }
3313
3314 else /* normal row; Adam7 only ever gives us one pixel to copy. */
3315 bytes_to_copy = pixel_depth;
3316
3317 /* In Adam7 there is a constant offset between where the pixels go. */
3318 bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
3319
3320 /* And simply copy these bytes. Some optimization is possible here,
3321 * depending on the value of 'bytes_to_copy'. Special case the low
3322 * byte counts, which we know to be frequent.
3323 *
3324 * Notice that these cases all 'return' rather than 'break' - this
3325 * avoids an unnecessary test on whether to restore the last byte
3326 * below.
3327 */
3328 switch (bytes_to_copy)
3329 {
3330 case 1:
3331 for (;;)
3332 {
3333 *dp = *sp;
3334
3335 if (row_width <= bytes_to_jump)
3336 return;
3337
3338 dp += bytes_to_jump;
3339 sp += bytes_to_jump;
3340 row_width -= bytes_to_jump;
3341 }
3342
3343 case 2:
3344 /* There is a possibility of a partial copy at the end here; this
3345 * slows the code down somewhat.
3346 */
3347 do
3348 {
3349 dp[0] = sp[0], dp[1] = sp[1];
3350
3351 if (row_width <= bytes_to_jump)
3352 return;
3353
3354 sp += bytes_to_jump;
3355 dp += bytes_to_jump;
3356 row_width -= bytes_to_jump;
3357 }
3358 while (row_width > 1);
3359
3360 /* And there can only be one byte left at this point: */
3361 *dp = *sp;
3362 return;
3363
3364 case 3:
3365 /* This can only be the RGB case, so each copy is exactly one
3366 * pixel and it is not necessary to check for a partial copy.
3367 */
3368 for(;;)
3369 {
3370 dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
3371
3372 if (row_width <= bytes_to_jump)
3373 return;
3374
3375 sp += bytes_to_jump;
3376 dp += bytes_to_jump;
3377 row_width -= bytes_to_jump;
3378 }
3379
3380 default:
3381 #if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
3382 /* Check for double byte alignment and, if possible, use a
3383 * 16-bit copy. Don't attempt this for narrow images - ones that
3384 * are less than an interlace panel wide. Don't attempt it for
3385 * wide bytes_to_copy either - use the memcpy there.
3386 */
3387 if (bytes_to_copy < 16 /*else use memcpy*/ &&
3388 png_isaligned(dp, png_uint_16) &&
3389 png_isaligned(sp, png_uint_16) &&
3390 bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
3391 bytes_to_jump % (sizeof (png_uint_16)) == 0)
3392 {
3393 /* Everything is aligned for png_uint_16 copies, but try for
3394 * png_uint_32 first.
3395 */
3396 if (png_isaligned(dp, png_uint_32) &&
3397 png_isaligned(sp, png_uint_32) &&
3398 bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
3399 bytes_to_jump % (sizeof (png_uint_32)) == 0)
3400 {
3401 png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
3402 png_const_uint_32p sp32 = png_aligncastconst(
3403 png_const_uint_32p, sp);
3404 size_t skip = (bytes_to_jump-bytes_to_copy) /
3405 (sizeof (png_uint_32));
3406
3407 do
3408 {
3409 size_t c = bytes_to_copy;
3410 do
3411 {
3412 *dp32++ = *sp32++;
3413 c -= (sizeof (png_uint_32));
3414 }
3415 while (c > 0);
3416
3417 if (row_width <= bytes_to_jump)
3418 return;
3419
3420 dp32 += skip;
3421 sp32 += skip;
3422 row_width -= bytes_to_jump;
3423 }
3424 while (bytes_to_copy <= row_width);
3425
3426 /* Get to here when the row_width truncates the final copy.
3427 * There will be 1-3 bytes left to copy, so don't try the
3428 * 16-bit loop below.
3429 */
3430 dp = (png_bytep)dp32;
3431 sp = (png_const_bytep)sp32;
3432 do
3433 *dp++ = *sp++;
3434 while (--row_width > 0);
3435 return;
3436 }
3437
3438 /* Else do it in 16-bit quantities, but only if the size is
3439 * not too large.
3440 */
3441 else
3442 {
3443 png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
3444 png_const_uint_16p sp16 = png_aligncastconst(
3445 png_const_uint_16p, sp);
3446 size_t skip = (bytes_to_jump-bytes_to_copy) /
3447 (sizeof (png_uint_16));
3448
3449 do
3450 {
3451 size_t c = bytes_to_copy;
3452 do
3453 {
3454 *dp16++ = *sp16++;
3455 c -= (sizeof (png_uint_16));
3456 }
3457 while (c > 0);
3458
3459 if (row_width <= bytes_to_jump)
3460 return;
3461
3462 dp16 += skip;
3463 sp16 += skip;
3464 row_width -= bytes_to_jump;
3465 }
3466 while (bytes_to_copy <= row_width);
3467
3468 /* End of row - 1 byte left, bytes_to_copy > row_width: */
3469 dp = (png_bytep)dp16;
3470 sp = (png_const_bytep)sp16;
3471 do
3472 *dp++ = *sp++;
3473 while (--row_width > 0);
3474 return;
3475 }
3476 }
3477 #endif /* PNG_ALIGN_ code */
3478
3479 /* The true default - use a memcpy: */
3480 for (;;)
3481 {
3482 memcpy(dp, sp, bytes_to_copy);
3483
3484 if (row_width <= bytes_to_jump)
3485 return;
3486
3487 sp += bytes_to_jump;
3488 dp += bytes_to_jump;
3489 row_width -= bytes_to_jump;
3490 if (bytes_to_copy > row_width)
3491 bytes_to_copy = (unsigned int)/*SAFE*/row_width;
3492 }
3493 }
3494
3495 /* NOT REACHED*/
3496 } /* pixel_depth >= 8 */
3497
3498 /* Here if pixel_depth < 8 to check 'end_ptr' below. */
3499 }
3500 else
3501 #endif
3502
3503 /* If here then the switch above wasn't used so just memcpy the whole row
3504 * from the temporary row buffer (notice that this overwrites the end of the
3505 * destination row if it is a partial byte.)
3506 */
3507 memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
3508
3509 /* Restore the overwritten bits from the last byte if necessary. */
3510 if (end_ptr != NULL)
3511 *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
3512 }
3513
3514 #ifdef PNG_READ_INTERLACING_SUPPORTED
3515 void /* PRIVATE */
png_do_read_interlace(png_row_infop row_info,png_bytep row,int pass,png_uint_32 transformations)3516 png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
3517 png_uint_32 transformations /* Because these may affect the byte layout */)
3518 {
3519 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
3520 /* Offset to next interlace block */
3521 static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
3522
3523 png_debug(1, "in png_do_read_interlace");
3524 if (row != NULL && row_info != NULL)
3525 {
3526 png_uint_32 final_width;
3527
3528 final_width = row_info->width * png_pass_inc[pass];
3529
3530 switch (row_info->pixel_depth)
3531 {
3532 case 1:
3533 {
3534 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
3535 png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
3536 int sshift, dshift;
3537 int s_start, s_end, s_inc;
3538 int jstop = png_pass_inc[pass];
3539 png_byte v;
3540 png_uint_32 i;
3541 int j;
3542
3543 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3544 if (transformations & PNG_PACKSWAP)
3545 {
3546 sshift = (int)((row_info->width + 7) & 0x07);
3547 dshift = (int)((final_width + 7) & 0x07);
3548 s_start = 7;
3549 s_end = 0;
3550 s_inc = -1;
3551 }
3552
3553 else
3554 #endif
3555 {
3556 sshift = 7 - (int)((row_info->width + 7) & 0x07);
3557 dshift = 7 - (int)((final_width + 7) & 0x07);
3558 s_start = 0;
3559 s_end = 7;
3560 s_inc = 1;
3561 }
3562
3563 for (i = 0; i < row_info->width; i++)
3564 {
3565 v = (png_byte)((*sp >> sshift) & 0x01);
3566 for (j = 0; j < jstop; j++)
3567 {
3568 unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
3569 tmp |= v << dshift;
3570 *dp = (png_byte)(tmp & 0xff);
3571
3572 if (dshift == s_end)
3573 {
3574 dshift = s_start;
3575 dp--;
3576 }
3577
3578 else
3579 dshift += s_inc;
3580 }
3581
3582 if (sshift == s_end)
3583 {
3584 sshift = s_start;
3585 sp--;
3586 }
3587
3588 else
3589 sshift += s_inc;
3590 }
3591 break;
3592 }
3593
3594 case 2:
3595 {
3596 png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
3597 png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
3598 int sshift, dshift;
3599 int s_start, s_end, s_inc;
3600 int jstop = png_pass_inc[pass];
3601 png_uint_32 i;
3602
3603 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3604 if (transformations & PNG_PACKSWAP)
3605 {
3606 sshift = (int)(((row_info->width + 3) & 0x03) << 1);
3607 dshift = (int)(((final_width + 3) & 0x03) << 1);
3608 s_start = 6;
3609 s_end = 0;
3610 s_inc = -2;
3611 }
3612
3613 else
3614 #endif
3615 {
3616 sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
3617 dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
3618 s_start = 0;
3619 s_end = 6;
3620 s_inc = 2;
3621 }
3622
3623 for (i = 0; i < row_info->width; i++)
3624 {
3625 png_byte v;
3626 int j;
3627
3628 v = (png_byte)((*sp >> sshift) & 0x03);
3629 for (j = 0; j < jstop; j++)
3630 {
3631 unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
3632 tmp |= v << dshift;
3633 *dp = (png_byte)(tmp & 0xff);
3634
3635 if (dshift == s_end)
3636 {
3637 dshift = s_start;
3638 dp--;
3639 }
3640
3641 else
3642 dshift += s_inc;
3643 }
3644
3645 if (sshift == s_end)
3646 {
3647 sshift = s_start;
3648 sp--;
3649 }
3650
3651 else
3652 sshift += s_inc;
3653 }
3654 break;
3655 }
3656
3657 case 4:
3658 {
3659 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
3660 png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
3661 int sshift, dshift;
3662 int s_start, s_end, s_inc;
3663 png_uint_32 i;
3664 int jstop = png_pass_inc[pass];
3665
3666 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3667 if (transformations & PNG_PACKSWAP)
3668 {
3669 sshift = (int)(((row_info->width + 1) & 0x01) << 2);
3670 dshift = (int)(((final_width + 1) & 0x01) << 2);
3671 s_start = 4;
3672 s_end = 0;
3673 s_inc = -4;
3674 }
3675
3676 else
3677 #endif
3678 {
3679 sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
3680 dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
3681 s_start = 0;
3682 s_end = 4;
3683 s_inc = 4;
3684 }
3685
3686 for (i = 0; i < row_info->width; i++)
3687 {
3688 png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
3689 int j;
3690
3691 for (j = 0; j < jstop; j++)
3692 {
3693 unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
3694 tmp |= v << dshift;
3695 *dp = (png_byte)(tmp & 0xff);
3696
3697 if (dshift == s_end)
3698 {
3699 dshift = s_start;
3700 dp--;
3701 }
3702
3703 else
3704 dshift += s_inc;
3705 }
3706
3707 if (sshift == s_end)
3708 {
3709 sshift = s_start;
3710 sp--;
3711 }
3712
3713 else
3714 sshift += s_inc;
3715 }
3716 break;
3717 }
3718
3719 default:
3720 {
3721 png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
3722
3723 png_bytep sp = row + (png_size_t)(row_info->width - 1)
3724 * pixel_bytes;
3725
3726 png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
3727
3728 int jstop = png_pass_inc[pass];
3729 png_uint_32 i;
3730
3731 for (i = 0; i < row_info->width; i++)
3732 {
3733 png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
3734 int j;
3735
3736 memcpy(v, sp, pixel_bytes);
3737
3738 for (j = 0; j < jstop; j++)
3739 {
3740 memcpy(dp, v, pixel_bytes);
3741 dp -= pixel_bytes;
3742 }
3743
3744 sp -= pixel_bytes;
3745 }
3746 break;
3747 }
3748 }
3749
3750 row_info->width = final_width;
3751 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
3752 }
3753 #ifndef PNG_READ_PACKSWAP_SUPPORTED
3754 PNG_UNUSED(transformations) /* Silence compiler warning */
3755 #endif
3756 }
3757 #endif /* PNG_READ_INTERLACING_SUPPORTED */
3758
3759 static void
png_read_filter_row_sub(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3760 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
3761 png_const_bytep prev_row)
3762 {
3763 png_size_t i;
3764 png_size_t istop = row_info->rowbytes;
3765 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3766 png_bytep rp = row + bpp;
3767
3768 PNG_UNUSED(prev_row)
3769
3770 for (i = bpp; i < istop; i++)
3771 {
3772 *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
3773 rp++;
3774 }
3775 }
3776
3777 static void
png_read_filter_row_up(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3778 png_read_filter_row_up(png_row_infop row_info, png_bytep row,
3779 png_const_bytep prev_row)
3780 {
3781 png_size_t i;
3782 png_size_t istop = row_info->rowbytes;
3783 png_bytep rp = row;
3784 png_const_bytep pp = prev_row;
3785
3786 for (i = 0; i < istop; i++)
3787 {
3788 *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
3789 rp++;
3790 }
3791 }
3792
3793 static void
png_read_filter_row_avg(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3794 png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
3795 png_const_bytep prev_row)
3796 {
3797 png_size_t i;
3798 png_bytep rp = row;
3799 png_const_bytep pp = prev_row;
3800 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3801 png_size_t istop = row_info->rowbytes - bpp;
3802
3803 for (i = 0; i < bpp; i++)
3804 {
3805 *rp = (png_byte)(((int)(*rp) +
3806 ((int)(*pp++) / 2 )) & 0xff);
3807
3808 rp++;
3809 }
3810
3811 for (i = 0; i < istop; i++)
3812 {
3813 *rp = (png_byte)(((int)(*rp) +
3814 (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
3815
3816 rp++;
3817 }
3818 }
3819
3820 static void
png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3821 png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
3822 png_const_bytep prev_row)
3823 {
3824 png_bytep rp_end = row + row_info->rowbytes;
3825 int a, c;
3826
3827 /* First pixel/byte */
3828 c = *prev_row++;
3829 a = *row + c;
3830 *row++ = (png_byte)a;
3831
3832 /* Remainder */
3833 while (row < rp_end)
3834 {
3835 int b, pa, pb, pc, p;
3836
3837 a &= 0xff; /* From previous iteration or start */
3838 b = *prev_row++;
3839
3840 p = b - c;
3841 pc = a - c;
3842
3843 # ifdef PNG_USE_ABS
3844 pa = abs(p);
3845 pb = abs(pc);
3846 pc = abs(p + pc);
3847 # else
3848 pa = p < 0 ? -p : p;
3849 pb = pc < 0 ? -pc : pc;
3850 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3851 # endif
3852
3853 /* Find the best predictor, the least of pa, pb, pc favoring the earlier
3854 * ones in the case of a tie.
3855 */
3856 if (pb < pa) pa = pb, a = b;
3857 if (pc < pa) a = c;
3858
3859 /* Calculate the current pixel in a, and move the previous row pixel to c
3860 * for the next time round the loop
3861 */
3862 c = b;
3863 a += *row;
3864 *row++ = (png_byte)a;
3865 }
3866 }
3867
3868 static void
png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3869 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
3870 png_const_bytep prev_row)
3871 {
3872 int bpp = (row_info->pixel_depth + 7) >> 3;
3873 png_bytep rp_end = row + bpp;
3874
3875 /* Process the first pixel in the row completely (this is the same as 'up'
3876 * because there is only one candidate predictor for the first row).
3877 */
3878 while (row < rp_end)
3879 {
3880 int a = *row + *prev_row++;
3881 *row++ = (png_byte)a;
3882 }
3883
3884 /* Remainder */
3885 rp_end += row_info->rowbytes - bpp;
3886
3887 while (row < rp_end)
3888 {
3889 int a, b, c, pa, pb, pc, p;
3890
3891 c = *(prev_row - bpp);
3892 a = *(row - bpp);
3893 b = *prev_row++;
3894
3895 p = b - c;
3896 pc = a - c;
3897
3898 # ifdef PNG_USE_ABS
3899 pa = abs(p);
3900 pb = abs(pc);
3901 pc = abs(p + pc);
3902 # else
3903 pa = p < 0 ? -p : p;
3904 pb = pc < 0 ? -pc : pc;
3905 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3906 # endif
3907
3908 if (pb < pa) pa = pb, a = b;
3909 if (pc < pa) a = c;
3910
3911 a += *row;
3912 *row++ = (png_byte)a;
3913 }
3914 }
3915
3916 static void
png_init_filter_functions(png_structrp pp)3917 png_init_filter_functions(png_structrp pp)
3918 /* This function is called once for every PNG image (except for PNG images
3919 * that only use PNG_FILTER_VALUE_NONE for all rows) to set the
3920 * implementations required to reverse the filtering of PNG rows. Reversing
3921 * the filter is the first transformation performed on the row data. It is
3922 * performed in place, therefore an implementation can be selected based on
3923 * the image pixel format. If the implementation depends on image width then
3924 * take care to ensure that it works correctly if the image is interlaced -
3925 * interlacing causes the actual row width to vary.
3926 */
3927 {
3928 unsigned int bpp = (pp->pixel_depth + 7) >> 3;
3929
3930 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
3931 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
3932 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
3933 if (bpp == 1)
3934 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
3935 png_read_filter_row_paeth_1byte_pixel;
3936 else
3937 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
3938 png_read_filter_row_paeth_multibyte_pixel;
3939
3940 #ifdef PNG_FILTER_OPTIMIZATIONS
3941 /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
3942 * call to install hardware optimizations for the above functions; simply
3943 * replace whatever elements of the pp->read_filter[] array with a hardware
3944 * specific (or, for that matter, generic) optimization.
3945 *
3946 * To see an example of this examine what configure.ac does when
3947 * --enable-arm-neon is specified on the command line.
3948 */
3949 PNG_FILTER_OPTIMIZATIONS(pp, bpp);
3950 #endif
3951 }
3952
3953 void /* PRIVATE */
png_read_filter_row(png_structrp pp,png_row_infop row_info,png_bytep row,png_const_bytep prev_row,int filter)3954 png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
3955 png_const_bytep prev_row, int filter)
3956 {
3957 /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
3958 * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
3959 * implementations. See png_init_filter_functions above.
3960 */
3961 if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
3962 {
3963 if (pp->read_filter[0] == NULL)
3964 png_init_filter_functions(pp);
3965
3966 pp->read_filter[filter-1](row_info, row, prev_row);
3967 }
3968 }
3969
3970 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
3971 void /* PRIVATE */
png_read_IDAT_data(png_structrp png_ptr,png_bytep output,png_alloc_size_t avail_out)3972 png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
3973 png_alloc_size_t avail_out)
3974 {
3975 /* Loop reading IDATs and decompressing the result into output[avail_out] */
3976 png_ptr->zstream.next_out = output;
3977 png_ptr->zstream.avail_out = 0; /* safety: set below */
3978
3979 if (output == NULL)
3980 avail_out = 0;
3981
3982 do
3983 {
3984 int ret;
3985 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
3986
3987 if (png_ptr->zstream.avail_in == 0)
3988 {
3989 uInt avail_in;
3990 png_bytep buffer;
3991
3992 while (png_ptr->idat_size == 0)
3993 {
3994 #ifdef PNG_INDEX_SUPPORTED
3995 if (png_ptr->index) {
3996 png_opt_crc_finish(png_ptr, 0);
3997 png_ptr->index->stream_idat_position = png_ptr->total_data_read;
3998 } else
3999 #endif
4000 png_crc_finish(png_ptr, 0);
4001
4002 png_ptr->idat_size = png_read_chunk_header(png_ptr);
4003 /* This is an error even in the 'check' case because the code just
4004 * consumed a non-IDAT header.
4005 */
4006 if (png_ptr->chunk_name != png_IDAT)
4007 png_error(png_ptr, "Not enough image data");
4008 }
4009
4010 avail_in = png_ptr->IDAT_read_size;
4011
4012 if (avail_in > png_ptr->idat_size)
4013 avail_in = (uInt)png_ptr->idat_size;
4014
4015 /* A PNG with a gradually increasing IDAT size will defeat this attempt
4016 * to minimize memory usage by causing lots of re-allocs, but
4017 * realistically doing IDAT_read_size re-allocs is not likely to be a
4018 * big problem.
4019 */
4020 buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
4021
4022 png_crc_read(png_ptr, buffer, avail_in);
4023 png_ptr->idat_size -= avail_in;
4024
4025 png_ptr->zstream.next_in = buffer;
4026 png_ptr->zstream.avail_in = avail_in;
4027 }
4028
4029 /* And set up the output side. */
4030 if (output != NULL) /* standard read */
4031 {
4032 uInt out = ZLIB_IO_MAX;
4033
4034 if (out > avail_out)
4035 out = (uInt)avail_out;
4036
4037 avail_out -= out;
4038 png_ptr->zstream.avail_out = out;
4039 }
4040
4041 else /* after last row, checking for end */
4042 {
4043 png_ptr->zstream.next_out = tmpbuf;
4044 png_ptr->zstream.avail_out = (sizeof tmpbuf);
4045 }
4046
4047 /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
4048 * process. If the LZ stream is truncated the sequential reader will
4049 * terminally damage the stream, above, by reading the chunk header of the
4050 * following chunk (it then exits with png_error).
4051 *
4052 * TODO: deal more elegantly with truncated IDAT lists.
4053 */
4054 ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
4055
4056 /* Take the unconsumed output back. */
4057 if (output != NULL)
4058 avail_out += png_ptr->zstream.avail_out;
4059
4060 else /* avail_out counts the extra bytes */
4061 avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
4062
4063 png_ptr->zstream.avail_out = 0;
4064
4065 if (ret == Z_STREAM_END)
4066 {
4067 /* Do this for safety; we won't read any more into this row. */
4068 png_ptr->zstream.next_out = NULL;
4069
4070 png_ptr->mode |= PNG_AFTER_IDAT;
4071 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4072
4073 if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
4074 png_chunk_benign_error(png_ptr, "Extra compressed data");
4075 break;
4076 }
4077
4078 if (ret != Z_OK)
4079 #ifdef PNG_INDEX_SUPPORTED
4080 if (png_ptr->index && png_ptr->row_number != png_ptr->height - 1)
4081 #endif
4082 {
4083 png_zstream_error(png_ptr, ret);
4084
4085 if (output != NULL)
4086 png_chunk_error(png_ptr, png_ptr->zstream.msg);
4087
4088 else /* checking */
4089 {
4090 png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
4091 return;
4092 }
4093 }
4094 } while (avail_out > 0);
4095
4096 if (avail_out > 0)
4097 {
4098 /* The stream ended before the image; this is the same as too few IDATs so
4099 * should be handled the same way.
4100 */
4101 if (output != NULL)
4102 png_error(png_ptr, "Not enough image data");
4103
4104 else /* the deflate stream contained extra data */
4105 png_chunk_benign_error(png_ptr, "Too much image data");
4106 }
4107 }
4108
4109 void /* PRIVATE */
png_read_finish_IDAT(png_structrp png_ptr)4110 png_read_finish_IDAT(png_structrp png_ptr)
4111 {
4112 /* We don't need any more data and the stream should have ended, however the
4113 * LZ end code may actually not have been processed. In this case we must
4114 * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
4115 * may still remain to be consumed.
4116 */
4117 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
4118 {
4119 /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
4120 * the compressed stream, but the stream may be damaged too, so even after
4121 * this call we may need to terminate the zstream ownership.
4122 */
4123 png_read_IDAT_data(png_ptr, NULL, 0);
4124 png_ptr->zstream.next_out = NULL; /* safety */
4125
4126 /* Now clear everything out for safety; the following may not have been
4127 * done.
4128 */
4129 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
4130 {
4131 png_ptr->mode |= PNG_AFTER_IDAT;
4132 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4133 }
4134 }
4135
4136 /* If the zstream has not been released do it now *and* terminate the reading
4137 * of the final IDAT chunk.
4138 */
4139 if (png_ptr->zowner == png_IDAT)
4140 {
4141 /* Always do this; the pointers otherwise point into the read buffer. */
4142 png_ptr->zstream.next_in = NULL;
4143 png_ptr->zstream.avail_in = 0;
4144
4145 /* Now we no longer own the zstream. */
4146 png_ptr->zowner = 0;
4147
4148 /* The slightly weird semantics of the sequential IDAT reading is that we
4149 * are always in or at the end of an IDAT chunk, so we always need to do a
4150 * crc_finish here. If idat_size is non-zero we also need to read the
4151 * spurious bytes at the end of the chunk now.
4152 */
4153 #ifdef PNG_INDEX_SUPPORTED
4154 if (png_ptr->index)
4155 {
4156 (void)png_opt_crc_finish(png_ptr, png_ptr->idat_size);
4157 png_ptr->index->stream_idat_position = png_ptr->total_data_read;
4158 }
4159 else
4160 #endif
4161 (void)png_crc_finish(png_ptr, png_ptr->idat_size);
4162 }
4163 }
4164
4165 #ifdef PNG_INDEX_SUPPORTED
4166 void /* PRIVATE */
png_set_interlaced_pass(png_structp png_ptr,int pass)4167 png_set_interlaced_pass(png_structp png_ptr, int pass)
4168 {
4169 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4170 /* Start of interlace block */
4171 PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4172 /* Offset to next interlace block */
4173 PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4174 /* Start of interlace block in the y direction */
4175 PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4176 /* Offset to next interlace block in the y direction */
4177 PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4178 png_ptr->pass = pass;
4179 png_ptr->iwidth = (png_ptr->width +
4180 png_pass_inc[png_ptr->pass] - 1 -
4181 png_pass_start[png_ptr->pass]) /
4182 png_pass_inc[png_ptr->pass];
4183 }
4184 #endif
4185
4186 void /* PRIVATE */
png_read_finish_row(png_structrp png_ptr)4187 png_read_finish_row(png_structrp png_ptr)
4188 {
4189 #ifdef PNG_READ_INTERLACING_SUPPORTED
4190 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4191
4192 /* Start of interlace block */
4193 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4194
4195 /* Offset to next interlace block */
4196 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4197
4198 /* Start of interlace block in the y direction */
4199 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4200
4201 /* Offset to next interlace block in the y direction */
4202 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4203 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4204
4205 png_debug(1, "in png_read_finish_row");
4206 png_ptr->row_number++;
4207 if (png_ptr->row_number < png_ptr->num_rows)
4208 return;
4209
4210 #ifdef PNG_READ_INTERLACING_SUPPORTED
4211 if (png_ptr->interlaced)
4212 {
4213 png_ptr->row_number = 0;
4214
4215 /* TO DO: don't do this if prev_row isn't needed (requires
4216 * read-ahead of the next row's filter byte.
4217 */
4218 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4219
4220 do
4221 {
4222 png_ptr->pass++;
4223
4224 if (png_ptr->pass >= 7)
4225 break;
4226
4227 png_ptr->iwidth = (png_ptr->width +
4228 png_pass_inc[png_ptr->pass] - 1 -
4229 png_pass_start[png_ptr->pass]) /
4230 png_pass_inc[png_ptr->pass];
4231
4232 if (!(png_ptr->transformations & PNG_INTERLACE))
4233 {
4234 png_ptr->num_rows = (png_ptr->height +
4235 png_pass_yinc[png_ptr->pass] - 1 -
4236 png_pass_ystart[png_ptr->pass]) /
4237 png_pass_yinc[png_ptr->pass];
4238 }
4239
4240 else /* if (png_ptr->transformations & PNG_INTERLACE) */
4241 break; /* libpng deinterlacing sees every row */
4242
4243 } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
4244
4245 if (png_ptr->pass < 7)
4246 return;
4247 }
4248 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4249
4250 /* Here after at the end of the last row of the last pass. */
4251 png_read_finish_IDAT(png_ptr);
4252 }
4253 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
4254
4255 void /* PRIVATE */
png_read_start_row(png_structrp png_ptr)4256 png_read_start_row(png_structrp png_ptr)
4257 {
4258 #ifdef PNG_READ_INTERLACING_SUPPORTED
4259 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4260
4261 /* Start of interlace block */
4262 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4263
4264 /* Offset to next interlace block */
4265 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4266
4267 /* Start of interlace block in the y direction */
4268 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4269
4270 /* Offset to next interlace block in the y direction */
4271 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4272 #endif
4273
4274 int max_pixel_depth;
4275 png_size_t row_bytes;
4276
4277 png_debug(1, "in png_read_start_row");
4278
4279 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
4280 png_init_read_transformations(png_ptr);
4281 #endif
4282 #ifdef PNG_READ_INTERLACING_SUPPORTED
4283 if (png_ptr->interlaced)
4284 {
4285 if (!(png_ptr->transformations & PNG_INTERLACE))
4286 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
4287 png_pass_ystart[0]) / png_pass_yinc[0];
4288
4289 else
4290 png_ptr->num_rows = png_ptr->height;
4291
4292 png_ptr->iwidth = (png_ptr->width +
4293 png_pass_inc[png_ptr->pass] - 1 -
4294 png_pass_start[png_ptr->pass]) /
4295 png_pass_inc[png_ptr->pass];
4296 }
4297
4298 else
4299 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4300 {
4301 png_ptr->num_rows = png_ptr->height;
4302 png_ptr->iwidth = png_ptr->width;
4303 }
4304
4305 max_pixel_depth = png_ptr->pixel_depth;
4306
4307 /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of
4308 * calculations to calculate the final pixel depth, then
4309 * png_do_read_transforms actually does the transforms. This means that the
4310 * code which effectively calculates this value is actually repeated in three
4311 * separate places. They must all match. Innocent changes to the order of
4312 * transformations can and will break libpng in a way that causes memory
4313 * overwrites.
4314 *
4315 * TODO: fix this.
4316 */
4317 #ifdef PNG_READ_PACK_SUPPORTED
4318 if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
4319 max_pixel_depth = 8;
4320 #endif
4321
4322 #ifdef PNG_READ_EXPAND_SUPPORTED
4323 if (png_ptr->transformations & PNG_EXPAND)
4324 {
4325 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4326 {
4327 if (png_ptr->num_trans)
4328 max_pixel_depth = 32;
4329
4330 else
4331 max_pixel_depth = 24;
4332 }
4333
4334 else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4335 {
4336 if (max_pixel_depth < 8)
4337 max_pixel_depth = 8;
4338
4339 if (png_ptr->num_trans)
4340 max_pixel_depth *= 2;
4341 }
4342
4343 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
4344 {
4345 if (png_ptr->num_trans)
4346 {
4347 max_pixel_depth *= 4;
4348 max_pixel_depth /= 3;
4349 }
4350 }
4351 }
4352 #endif
4353
4354 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4355 if (png_ptr->transformations & PNG_EXPAND_16)
4356 {
4357 # ifdef PNG_READ_EXPAND_SUPPORTED
4358 /* In fact it is an error if it isn't supported, but checking is
4359 * the safe way.
4360 */
4361 if (png_ptr->transformations & PNG_EXPAND)
4362 {
4363 if (png_ptr->bit_depth < 16)
4364 max_pixel_depth *= 2;
4365 }
4366 else
4367 # endif
4368 png_ptr->transformations &= ~PNG_EXPAND_16;
4369 }
4370 #endif
4371
4372 #ifdef PNG_READ_FILLER_SUPPORTED
4373 if (png_ptr->transformations & (PNG_FILLER))
4374 {
4375 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4376 {
4377 if (max_pixel_depth <= 8)
4378 max_pixel_depth = 16;
4379
4380 else
4381 max_pixel_depth = 32;
4382 }
4383
4384 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
4385 png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4386 {
4387 if (max_pixel_depth <= 32)
4388 max_pixel_depth = 32;
4389
4390 else
4391 max_pixel_depth = 64;
4392 }
4393 }
4394 #endif
4395
4396 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4397 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
4398 {
4399 if (
4400 #ifdef PNG_READ_EXPAND_SUPPORTED
4401 (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
4402 #endif
4403 #ifdef PNG_READ_FILLER_SUPPORTED
4404 (png_ptr->transformations & (PNG_FILLER)) ||
4405 #endif
4406 png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4407 {
4408 if (max_pixel_depth <= 16)
4409 max_pixel_depth = 32;
4410
4411 else
4412 max_pixel_depth = 64;
4413 }
4414
4415 else
4416 {
4417 if (max_pixel_depth <= 8)
4418 {
4419 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4420 max_pixel_depth = 32;
4421
4422 else
4423 max_pixel_depth = 24;
4424 }
4425
4426 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4427 max_pixel_depth = 64;
4428
4429 else
4430 max_pixel_depth = 48;
4431 }
4432 }
4433 #endif
4434
4435 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
4436 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
4437 if (png_ptr->transformations & PNG_USER_TRANSFORM)
4438 {
4439 int user_pixel_depth = png_ptr->user_transform_depth *
4440 png_ptr->user_transform_channels;
4441
4442 if (user_pixel_depth > max_pixel_depth)
4443 max_pixel_depth = user_pixel_depth;
4444 }
4445 #endif
4446
4447 /* This value is stored in png_struct and double checked in the row read
4448 * code.
4449 */
4450 png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
4451 png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
4452
4453 /* Align the width on the next larger 8 pixels. Mainly used
4454 * for interlacing
4455 */
4456 row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
4457 /* Calculate the maximum bytes needed, adding a byte and a pixel
4458 * for safety's sake
4459 */
4460 row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
4461 1 + ((max_pixel_depth + 7) >> 3);
4462
4463 #ifdef PNG_MAX_MALLOC_64K
4464 if (row_bytes > (png_uint_32)65536L)
4465 png_error(png_ptr, "This image requires a row greater than 64KB");
4466 #endif
4467
4468 if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
4469 {
4470 png_free(png_ptr, png_ptr->big_row_buf);
4471 png_free(png_ptr, png_ptr->big_prev_row);
4472
4473 if (png_ptr->interlaced)
4474 png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
4475 row_bytes + 48);
4476
4477 else
4478 png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4479
4480 png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4481
4482 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
4483 /* Use 16-byte aligned memory for row_buf with at least 16 bytes
4484 * of padding before and after row_buf; treat prev_row similarly.
4485 * NOTE: the alignment is to the start of the pixels, one beyond the start
4486 * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this
4487 * was incorrect; the filter byte was aligned, which had the exact
4488 * opposite effect of that intended.
4489 */
4490 {
4491 png_bytep temp = png_ptr->big_row_buf + 32;
4492 int extra = (int)((temp - (png_bytep)0) & 0x0f);
4493 png_ptr->row_buf = temp - extra - 1/*filter byte*/;
4494
4495 temp = png_ptr->big_prev_row + 32;
4496 extra = (int)((temp - (png_bytep)0) & 0x0f);
4497 png_ptr->prev_row = temp - extra - 1/*filter byte*/;
4498 }
4499
4500 #else
4501 /* Use 31 bytes of padding before and 17 bytes after row_buf. */
4502 png_ptr->row_buf = png_ptr->big_row_buf + 31;
4503 png_ptr->prev_row = png_ptr->big_prev_row + 31;
4504 #endif
4505 png_ptr->old_big_row_buf_size = row_bytes + 48;
4506 }
4507
4508 #ifdef PNG_MAX_MALLOC_64K
4509 if (png_ptr->rowbytes > 65535)
4510 png_error(png_ptr, "This image requires a row greater than 64KB");
4511
4512 #endif
4513 if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
4514 png_error(png_ptr, "Row has too many bytes to allocate in memory");
4515
4516 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4517
4518 png_debug1(3, "width = %u,", png_ptr->width);
4519 png_debug1(3, "height = %u,", png_ptr->height);
4520 png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
4521 png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
4522 png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
4523 png_debug1(3, "irowbytes = %lu",
4524 (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
4525
4526 /* The sequential reader needs a buffer for IDAT, but the progressive reader
4527 * does not, so free the read buffer now regardless; the sequential reader
4528 * reallocates it on demand.
4529 */
4530 if (png_ptr->read_buffer)
4531 {
4532 png_bytep buffer = png_ptr->read_buffer;
4533
4534 png_ptr->read_buffer_size = 0;
4535 png_ptr->read_buffer = NULL;
4536 png_free(png_ptr, buffer);
4537 }
4538
4539 /* Finally claim the zstream for the inflate of the IDAT data, use the bits
4540 * value from the stream (note that this will result in a fatal error if the
4541 * IDAT stream has a bogus deflate header window_bits value, but this should
4542 * not be happening any longer!)
4543 */
4544 if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
4545 png_error(png_ptr, png_ptr->zstream.msg);
4546
4547 png_ptr->flags |= PNG_FLAG_ROW_INIT;
4548 }
4549 #endif /* PNG_READ_SUPPORTED */
4550