1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngrutil.c - utilities to read a PNG file
26 *
27 * Copyright (c) 2018 Cosmin Truta
28 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
29 * Copyright (c) 1996-1997 Andreas Dilger
30 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
31 *
32 * This code is released under the libpng license.
33 * For conditions of distribution and use, see the disclaimer
34 * and license in png.h
35 *
36 * This file contains routines that are only called from within
37 * libpng itself during the course of reading an image.
38 */
39
40 #include "pngpriv.h"
41
42 #ifdef PNG_READ_SUPPORTED
43
44 png_uint_32 PNGAPI
45 png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
46 {
47 png_uint_32 uval = png_get_uint_32(buf);
48
49 if (uval > PNG_UINT_31_MAX)
50 png_error(png_ptr, "PNG unsigned integer out of range");
51
52 return (uval);
53 }
54
55 #if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
56 /* The following is a variation on the above for use with the fixed
57 * point values used for gAMA and cHRM. Instead of png_error it
58 * issues a warning and returns (-1) - an invalid value because both
59 * gAMA and cHRM use *unsigned* integers for fixed point values.
60 */
61 #define PNG_FIXED_ERROR (-1)
62
63 static png_fixed_point /* PRIVATE */
64 png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
65 {
66 png_uint_32 uval = png_get_uint_32(buf);
67
68 if (uval <= PNG_UINT_31_MAX)
69 return (png_fixed_point)uval; /* known to be in range */
70
71 /* The caller can turn off the warning by passing NULL. */
72 if (png_ptr != NULL)
73 png_warning(png_ptr, "PNG fixed point integer out of range");
74
75 return PNG_FIXED_ERROR;
76 }
77 #endif
78
79 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
80 /* NOTE: the read macros will obscure these definitions, so that if
81 * PNG_USE_READ_MACROS is set the library will not use them internally,
82 * but the APIs will still be available externally.
83 *
84 * The parentheses around "PNGAPI function_name" in the following three
85 * functions are necessary because they allow the macros to co-exist with
86 * these (unused but exported) functions.
87 */
88
89 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
90 png_uint_32 (PNGAPI
91 png_get_uint_32)(png_const_bytep buf)
92 {
93 png_uint_32 uval =
94 ((png_uint_32)(*(buf )) << 24) +
95 ((png_uint_32)(*(buf + 1)) << 16) +
96 ((png_uint_32)(*(buf + 2)) << 8) +
97 ((png_uint_32)(*(buf + 3)) ) ;
98
99 return uval;
100 }
101
102 /* Grab a signed 32-bit integer from a buffer in big-endian format. The
103 * data is stored in the PNG file in two's complement format and there
104 * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
105 * the following code does a two's complement to native conversion.
106 */
107 png_int_32 (PNGAPI
108 png_get_int_32)(png_const_bytep buf)
109 {
110 png_uint_32 uval = png_get_uint_32(buf);
111 if ((uval & 0x80000000) == 0) /* non-negative */
112 return (png_int_32)uval;
113
114 uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */
115 if ((uval & 0x80000000) == 0) /* no overflow */
116 return -(png_int_32)uval;
117 /* The following has to be safe; this function only gets called on PNG data
118 * and if we get here that data is invalid. 0 is the most safe value and
119 * if not then an attacker would surely just generate a PNG with 0 instead.
120 */
121 return 0;
122 }
123
124 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
125 png_uint_16 (PNGAPI
126 png_get_uint_16)(png_const_bytep buf)
127 {
128 /* ANSI-C requires an int value to accommodate at least 16 bits so this
129 * works and allows the compiler not to worry about possible narrowing
130 * on 32-bit systems. (Pre-ANSI systems did not make integers smaller
131 * than 16 bits either.)
132 */
133 unsigned int val =
134 ((unsigned int)(*buf) << 8) +
135 ((unsigned int)(*(buf + 1)));
136
137 return (png_uint_16)val;
138 }
139
140 #endif /* READ_INT_FUNCTIONS */
141
142 /* Read and check the PNG file signature */
143 void /* PRIVATE */
144 png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
145 {
146 size_t num_checked, num_to_check;
147
148 /* Exit if the user application does not expect a signature. */
149 if (png_ptr->sig_bytes >= 8)
150 return;
151
152 num_checked = png_ptr->sig_bytes;
153 num_to_check = 8 - num_checked;
154
155 #ifdef PNG_IO_STATE_SUPPORTED
156 png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
157 #endif
158
159 /* The signature must be serialized in a single I/O call. */
160 png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
161 png_ptr->sig_bytes = 8;
162
163 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check) != 0)
164 {
165 if (num_checked < 4 &&
166 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
167 png_error(png_ptr, "Not a PNG file");
168 else
169 png_error(png_ptr, "PNG file corrupted by ASCII conversion");
170 }
171 if (num_checked < 3)
172 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
173 }
174
175 /* Read the chunk header (length + type name).
176 * Put the type name into png_ptr->chunk_name, and return the length.
177 */
178 png_uint_32 /* PRIVATE */
179 png_read_chunk_header(png_structrp png_ptr)
180 {
181 png_byte buf[8];
182 png_uint_32 length;
183
184 #ifdef PNG_IO_STATE_SUPPORTED
185 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
186 #endif
187
188 /* Read the length and the chunk name.
189 * This must be performed in a single I/O call.
190 */
191 png_read_data(png_ptr, buf, 8);
192 length = png_get_uint_31(png_ptr, buf);
193
194 /* Put the chunk name into png_ptr->chunk_name. */
195 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
196
197 png_debug2(0, "Reading %lx chunk, length = %lu",
198 (unsigned long)png_ptr->chunk_name, (unsigned long)length);
199
200 /* Reset the crc and run it over the chunk name. */
201 png_reset_crc(png_ptr);
202 png_calculate_crc(png_ptr, buf + 4, 4);
203
204 /* Check to see if chunk name is valid. */
205 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
206
207 /* Check for too-large chunk length */
208 png_check_chunk_length(png_ptr, length);
209
210 #ifdef PNG_IO_STATE_SUPPORTED
211 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
212 #endif
213
214 return length;
215 }
216
217 /* Read data, and (optionally) run it through the CRC. */
218 void /* PRIVATE */
219 png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
220 {
221 if (png_ptr == NULL)
222 return;
223
224 png_read_data(png_ptr, buf, length);
225 png_calculate_crc(png_ptr, buf, length);
226 }
227
228 /* Optionally skip data and then check the CRC. Depending on whether we
229 * are reading an ancillary or critical chunk, and how the program has set
230 * things up, we may calculate the CRC on the data and print a message.
231 * Returns '1' if there was a CRC error, '0' otherwise.
232 */
233 int /* PRIVATE */
234 png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
235 {
236 /* The size of the local buffer for inflate is a good guess as to a
237 * reasonable size to use for buffering reads from the application.
238 */
239 while (skip > 0)
240 {
241 png_uint_32 len;
242 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
243
244 len = (sizeof tmpbuf);
245 if (len > skip)
246 len = skip;
247 skip -= len;
248
249 png_crc_read(png_ptr, tmpbuf, len);
250 }
251
252 if (png_crc_error(png_ptr) != 0)
253 {
254 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0 ?
255 (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0 :
256 (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE) != 0)
257 {
258 png_chunk_warning(png_ptr, "CRC error");
259 }
260
261 else
262 png_chunk_error(png_ptr, "CRC error");
263
264 return (1);
265 }
266
267 return (0);
268 }
269
270 /* Compare the CRC stored in the PNG file with that calculated by libpng from
271 * the data it has read thus far.
272 */
273 int /* PRIVATE */
274 png_crc_error(png_structrp png_ptr)
275 {
276 png_byte crc_bytes[4];
277 png_uint_32 crc;
278 int need_crc = 1;
279
280 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
281 {
282 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
283 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
284 need_crc = 0;
285 }
286
287 else /* critical */
288 {
289 if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
290 need_crc = 0;
291 }
292
293 #ifdef PNG_IO_STATE_SUPPORTED
294 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
295 #endif
296
297 /* The chunk CRC must be serialized in a single I/O call. */
298 png_read_data(png_ptr, crc_bytes, 4);
299
300 if (need_crc != 0)
301 {
302 crc = png_get_uint_32(crc_bytes);
303 return ((int)(crc != png_ptr->crc));
304 }
305
306 else
307 return (0);
308 }
309
310 #if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
311 defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
312 defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
313 defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
314 /* Manage the read buffer; this simply reallocates the buffer if it is not small
315 * enough (or if it is not allocated). The routine returns a pointer to the
316 * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
317 * it will call png_error (via png_malloc) on failure. (warn == 2 means
318 * 'silent').
319 */
320 static png_bytep
321 png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
322 {
323 png_bytep buffer = png_ptr->read_buffer;
324
325 if (buffer != NULL && new_size > png_ptr->read_buffer_size)
326 {
327 png_ptr->read_buffer = NULL;
328 png_ptr->read_buffer = NULL;
329 png_ptr->read_buffer_size = 0;
330 png_free(png_ptr, buffer);
331 buffer = NULL;
332 }
333
334 if (buffer == NULL)
335 {
336 buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
337
338 if (buffer != NULL)
339 {
340 memset(buffer, 0, new_size); /* just in case */
341 png_ptr->read_buffer = buffer;
342 png_ptr->read_buffer_size = new_size;
343 }
344
345 else if (warn < 2) /* else silent */
346 {
347 if (warn != 0)
348 png_chunk_warning(png_ptr, "insufficient memory to read chunk");
349
350 else
351 png_chunk_error(png_ptr, "insufficient memory to read chunk");
352 }
353 }
354
355 return buffer;
356 }
357 #endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
358
359 /* png_inflate_claim: claim the zstream for some nefarious purpose that involves
360 * decompression. Returns Z_OK on success, else a zlib error code. It checks
361 * the owner but, in final release builds, just issues a warning if some other
362 * chunk apparently owns the stream. Prior to release it does a png_error.
363 */
364 static int
365 png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
366 {
367 if (png_ptr->zowner != 0)
368 {
369 char msg[64];
370
371 PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
372 /* So the message that results is "<chunk> using zstream"; this is an
373 * internal error, but is very useful for debugging. i18n requirements
374 * are minimal.
375 */
376 (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
377 #if PNG_RELEASE_BUILD
378 png_chunk_warning(png_ptr, msg);
379 png_ptr->zowner = 0;
380 #else
381 png_chunk_error(png_ptr, msg);
382 #endif
383 }
384
385 /* Implementation note: unlike 'png_deflate_claim' this internal function
386 * does not take the size of the data as an argument. Some efficiency could
387 * be gained by using this when it is known *if* the zlib stream itself does
388 * not record the number; however, this is an illusion: the original writer
389 * of the PNG may have selected a lower window size, and we really must
390 * follow that because, for systems with with limited capabilities, we
391 * would otherwise reject the application's attempts to use a smaller window
392 * size (zlib doesn't have an interface to say "this or lower"!).
393 *
394 * inflateReset2 was added to zlib 1.2.4; before this the window could not be
395 * reset, therefore it is necessary to always allocate the maximum window
396 * size with earlier zlibs just in case later compressed chunks need it.
397 */
398 {
399 int ret; /* zlib return code */
400 #if ZLIB_VERNUM >= 0x1240
401 int window_bits = 0;
402
403 # if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
404 if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
405 PNG_OPTION_ON)
406 {
407 window_bits = 15;
408 png_ptr->zstream_start = 0; /* fixed window size */
409 }
410
411 else
412 {
413 png_ptr->zstream_start = 1;
414 }
415 # endif
416
417 #endif /* ZLIB_VERNUM >= 0x1240 */
418
419 /* Set this for safety, just in case the previous owner left pointers to
420 * memory allocations.
421 */
422 png_ptr->zstream.next_in = NULL;
423 png_ptr->zstream.avail_in = 0;
424 png_ptr->zstream.next_out = NULL;
425 png_ptr->zstream.avail_out = 0;
426
427 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
428 {
429 #if ZLIB_VERNUM >= 0x1240
430 ret = inflateReset2(&png_ptr->zstream, window_bits);
431 #else
432 ret = inflateReset(&png_ptr->zstream);
433 #endif
434 }
435
436 else
437 {
438 #if ZLIB_VERNUM >= 0x1240
439 ret = inflateInit2(&png_ptr->zstream, window_bits);
440 #else
441 ret = inflateInit(&png_ptr->zstream);
442 #endif
443
444 if (ret == Z_OK)
445 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
446 }
447
448 #if ZLIB_VERNUM >= 0x1290 && \
449 defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_IGNORE_ADLER32)
450 if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON)
451 /* Turn off validation of the ADLER32 checksum in IDAT chunks */
452 ret = inflateValidate(&png_ptr->zstream, 0);
453 #endif
454
455 if (ret == Z_OK)
456 png_ptr->zowner = owner;
457
458 else
459 png_zstream_error(png_ptr, ret);
460
461 return ret;
462 }
463
464 #ifdef window_bits
465 # undef window_bits
466 #endif
467 }
468
469 #if ZLIB_VERNUM >= 0x1240
470 /* Handle the start of the inflate stream if we called inflateInit2(strm,0);
471 * in this case some zlib versions skip validation of the CINFO field and, in
472 * certain circumstances, libpng may end up displaying an invalid image, in
473 * contrast to implementations that call zlib in the normal way (e.g. libpng
474 * 1.5).
475 */
476 int /* PRIVATE */
477 png_zlib_inflate(png_structrp png_ptr, int flush)
478 {
479 if (png_ptr->zstream_start && png_ptr->zstream.avail_in > 0)
480 {
481 if ((*png_ptr->zstream.next_in >> 4) > 7)
482 {
483 png_ptr->zstream.msg = "invalid window size (libpng)";
484 return Z_DATA_ERROR;
485 }
486
487 png_ptr->zstream_start = 0;
488 }
489
490 return inflate(&png_ptr->zstream, flush);
491 }
492 #endif /* Zlib >= 1.2.4 */
493
494 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
495 #if defined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED)
496 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
497 * allow the caller to do multiple calls if required. If the 'finish' flag is
498 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
499 * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
500 * Z_OK or Z_STREAM_END will be returned on success.
501 *
502 * The input and output sizes are updated to the actual amounts of data consumed
503 * or written, not the amount available (as in a z_stream). The data pointers
504 * are not changed, so the next input is (data+input_size) and the next
505 * available output is (output+output_size).
506 */
507 static int
508 png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
509 /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
510 /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
511 {
512 if (png_ptr->zowner == owner) /* Else not claimed */
513 {
514 int ret;
515 png_alloc_size_t avail_out = *output_size_ptr;
516 png_uint_32 avail_in = *input_size_ptr;
517
518 /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
519 * can't even necessarily handle 65536 bytes) because the type uInt is
520 * "16 bits or more". Consequently it is necessary to chunk the input to
521 * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
522 * maximum value that can be stored in a uInt.) It is possible to set
523 * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
524 * a performance advantage, because it reduces the amount of data accessed
525 * at each step and that may give the OS more time to page it in.
526 */
527 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
528 /* avail_in and avail_out are set below from 'size' */
529 png_ptr->zstream.avail_in = 0;
530 png_ptr->zstream.avail_out = 0;
531
532 /* Read directly into the output if it is available (this is set to
533 * a local buffer below if output is NULL).
534 */
535 if (output != NULL)
536 png_ptr->zstream.next_out = output;
537
538 do
539 {
540 uInt avail;
541 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
542
543 /* zlib INPUT BUFFER */
544 /* The setting of 'avail_in' used to be outside the loop; by setting it
545 * inside it is possible to chunk the input to zlib and simply rely on
546 * zlib to advance the 'next_in' pointer. This allows arbitrary
547 * amounts of data to be passed through zlib at the unavoidable cost of
548 * requiring a window save (memcpy of up to 32768 output bytes)
549 * every ZLIB_IO_MAX input bytes.
550 */
551 avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
552
553 avail = ZLIB_IO_MAX;
554
555 if (avail_in < avail)
556 avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
557
558 avail_in -= avail;
559 png_ptr->zstream.avail_in = avail;
560
561 /* zlib OUTPUT BUFFER */
562 avail_out += png_ptr->zstream.avail_out; /* not written last time */
563
564 avail = ZLIB_IO_MAX; /* maximum zlib can process */
565
566 if (output == NULL)
567 {
568 /* Reset the output buffer each time round if output is NULL and
569 * make available the full buffer, up to 'remaining_space'
570 */
571 png_ptr->zstream.next_out = local_buffer;
572 if ((sizeof local_buffer) < avail)
573 avail = (sizeof local_buffer);
574 }
575
576 if (avail_out < avail)
577 avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
578
579 png_ptr->zstream.avail_out = avail;
580 avail_out -= avail;
581
582 /* zlib inflate call */
583 /* In fact 'avail_out' may be 0 at this point, that happens at the end
584 * of the read when the final LZ end code was not passed at the end of
585 * the previous chunk of input data. Tell zlib if we have reached the
586 * end of the output buffer.
587 */
588 ret = PNG_INFLATE(png_ptr, avail_out > 0 ? Z_NO_FLUSH :
589 (finish ? Z_FINISH : Z_SYNC_FLUSH));
590 } while (ret == Z_OK);
591
592 /* For safety kill the local buffer pointer now */
593 if (output == NULL)
594 png_ptr->zstream.next_out = NULL;
595
596 /* Claw back the 'size' and 'remaining_space' byte counts. */
597 avail_in += png_ptr->zstream.avail_in;
598 avail_out += png_ptr->zstream.avail_out;
599
600 /* Update the input and output sizes; the updated values are the amount
601 * consumed or written, effectively the inverse of what zlib uses.
602 */
603 if (avail_out > 0)
604 *output_size_ptr -= avail_out;
605
606 if (avail_in > 0)
607 *input_size_ptr -= avail_in;
608
609 /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
610 png_zstream_error(png_ptr, ret);
611 return ret;
612 }
613
614 else
615 {
616 /* This is a bad internal error. The recovery assigns to the zstream msg
617 * pointer, which is not owned by the caller, but this is safe; it's only
618 * used on errors!
619 */
620 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
621 return Z_STREAM_ERROR;
622 }
623 }
624
625 /*
626 * Decompress trailing data in a chunk. The assumption is that read_buffer
627 * points at an allocated area holding the contents of a chunk with a
628 * trailing compressed part. What we get back is an allocated area
629 * holding the original prefix part and an uncompressed version of the
630 * trailing part (the malloc area passed in is freed).
631 */
632 static int
633 png_decompress_chunk(png_structrp png_ptr,
634 png_uint_32 chunklength, png_uint_32 prefix_size,
635 png_alloc_size_t *newlength /* must be initialized to the maximum! */,
636 int terminate /*add a '\0' to the end of the uncompressed data*/)
637 {
638 /* TODO: implement different limits for different types of chunk.
639 *
640 * The caller supplies *newlength set to the maximum length of the
641 * uncompressed data, but this routine allocates space for the prefix and
642 * maybe a '\0' terminator too. We have to assume that 'prefix_size' is
643 * limited only by the maximum chunk size.
644 */
645 png_alloc_size_t limit = PNG_SIZE_MAX;
646
647 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
648 if (png_ptr->user_chunk_malloc_max > 0 &&
649 png_ptr->user_chunk_malloc_max < limit)
650 limit = png_ptr->user_chunk_malloc_max;
651 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
652 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
653 limit = PNG_USER_CHUNK_MALLOC_MAX;
654 # endif
655
656 if (limit >= prefix_size + (terminate != 0))
657 {
658 int ret;
659
660 limit -= prefix_size + (terminate != 0);
661
662 if (limit < *newlength)
663 *newlength = limit;
664
665 /* Now try to claim the stream. */
666 ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
667
668 if (ret == Z_OK)
669 {
670 png_uint_32 lzsize = chunklength - prefix_size;
671
672 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
673 /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
674 /* output: */ NULL, newlength);
675
676 if (ret == Z_STREAM_END)
677 {
678 /* Use 'inflateReset' here, not 'inflateReset2' because this
679 * preserves the previously decided window size (otherwise it would
680 * be necessary to store the previous window size.) In practice
681 * this doesn't matter anyway, because png_inflate will call inflate
682 * with Z_FINISH in almost all cases, so the window will not be
683 * maintained.
684 */
685 if (inflateReset(&png_ptr->zstream) == Z_OK)
686 {
687 /* Because of the limit checks above we know that the new,
688 * expanded, size will fit in a size_t (let alone an
689 * png_alloc_size_t). Use png_malloc_base here to avoid an
690 * extra OOM message.
691 */
692 png_alloc_size_t new_size = *newlength;
693 png_alloc_size_t buffer_size = prefix_size + new_size +
694 (terminate != 0);
695 png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
696 buffer_size));
697
698 if (text != NULL)
699 {
700 memset(text, 0, buffer_size);
701
702 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
703 png_ptr->read_buffer + prefix_size, &lzsize,
704 text + prefix_size, newlength);
705
706 if (ret == Z_STREAM_END)
707 {
708 if (new_size == *newlength)
709 {
710 if (terminate != 0)
711 text[prefix_size + *newlength] = 0;
712
713 if (prefix_size > 0)
714 memcpy(text, png_ptr->read_buffer, prefix_size);
715
716 {
717 png_bytep old_ptr = png_ptr->read_buffer;
718
719 png_ptr->read_buffer = text;
720 png_ptr->read_buffer_size = buffer_size;
721 text = old_ptr; /* freed below */
722 }
723 }
724
725 else
726 {
727 /* The size changed on the second read, there can be no
728 * guarantee that anything is correct at this point.
729 * The 'msg' pointer has been set to "unexpected end of
730 * LZ stream", which is fine, but return an error code
731 * that the caller won't accept.
732 */
733 ret = PNG_UNEXPECTED_ZLIB_RETURN;
734 }
735 }
736
737 else if (ret == Z_OK)
738 ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
739
740 /* Free the text pointer (this is the old read_buffer on
741 * success)
742 */
743 png_free(png_ptr, text);
744
745 /* This really is very benign, but it's still an error because
746 * the extra space may otherwise be used as a Trojan Horse.
747 */
748 if (ret == Z_STREAM_END &&
749 chunklength - prefix_size != lzsize)
750 png_chunk_benign_error(png_ptr, "extra compressed data");
751 }
752
753 else
754 {
755 /* Out of memory allocating the buffer */
756 ret = Z_MEM_ERROR;
757 png_zstream_error(png_ptr, Z_MEM_ERROR);
758 }
759 }
760
761 else
762 {
763 /* inflateReset failed, store the error message */
764 png_zstream_error(png_ptr, ret);
765 ret = PNG_UNEXPECTED_ZLIB_RETURN;
766 }
767 }
768
769 else if (ret == Z_OK)
770 ret = PNG_UNEXPECTED_ZLIB_RETURN;
771
772 /* Release the claimed stream */
773 png_ptr->zowner = 0;
774 }
775
776 else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
777 ret = PNG_UNEXPECTED_ZLIB_RETURN;
778
779 return ret;
780 }
781
782 else
783 {
784 /* Application/configuration limits exceeded */
785 png_zstream_error(png_ptr, Z_MEM_ERROR);
786 return Z_MEM_ERROR;
787 }
788 }
789 #endif /* READ_zTXt || READ_iTXt */
790 #endif /* READ_COMPRESSED_TEXT */
791
792 #ifdef PNG_READ_iCCP_SUPPORTED
793 /* Perform a partial read and decompress, producing 'avail_out' bytes and
794 * reading from the current chunk as required.
795 */
796 static int
797 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
798 png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
799 int finish)
800 {
801 if (png_ptr->zowner == png_ptr->chunk_name)
802 {
803 int ret;
804
805 /* next_in and avail_in must have been initialized by the caller. */
806 png_ptr->zstream.next_out = next_out;
807 png_ptr->zstream.avail_out = 0; /* set in the loop */
808
809 do
810 {
811 if (png_ptr->zstream.avail_in == 0)
812 {
813 if (read_size > *chunk_bytes)
814 read_size = (uInt)*chunk_bytes;
815 *chunk_bytes -= read_size;
816
817 if (read_size > 0)
818 png_crc_read(png_ptr, read_buffer, read_size);
819
820 png_ptr->zstream.next_in = read_buffer;
821 png_ptr->zstream.avail_in = read_size;
822 }
823
824 if (png_ptr->zstream.avail_out == 0)
825 {
826 uInt avail = ZLIB_IO_MAX;
827 if (avail > *out_size)
828 avail = (uInt)*out_size;
829 *out_size -= avail;
830
831 png_ptr->zstream.avail_out = avail;
832 }
833
834 /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
835 * the available output is produced; this allows reading of truncated
836 * streams.
837 */
838 ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ?
839 Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
840 }
841 while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
842
843 *out_size += png_ptr->zstream.avail_out;
844 png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
845
846 /* Ensure the error message pointer is always set: */
847 png_zstream_error(png_ptr, ret);
848 return ret;
849 }
850
851 else
852 {
853 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
854 return Z_STREAM_ERROR;
855 }
856 }
857 #endif /* READ_iCCP */
858
859 /* Read and check the IDHR chunk */
860
861 void /* PRIVATE */
862 png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
863 {
864 png_byte buf[13];
865 png_uint_32 width, height;
866 int bit_depth, color_type, compression_type, filter_type;
867 int interlace_type;
868
869 png_debug(1, "in png_handle_IHDR");
870
871 if ((png_ptr->mode & PNG_HAVE_IHDR) != 0)
872 png_chunk_error(png_ptr, "out of place");
873
874 /* Check the length */
875 if (length != 13)
876 png_chunk_error(png_ptr, "invalid");
877
878 png_ptr->mode |= PNG_HAVE_IHDR;
879
880 png_crc_read(png_ptr, buf, 13);
881 png_crc_finish(png_ptr, 0);
882
883 width = png_get_uint_31(png_ptr, buf);
884 height = png_get_uint_31(png_ptr, buf + 4);
885 bit_depth = buf[8];
886 color_type = buf[9];
887 compression_type = buf[10];
888 filter_type = buf[11];
889 interlace_type = buf[12];
890
891 /* Set internal variables */
892 png_ptr->width = width;
893 png_ptr->height = height;
894 png_ptr->bit_depth = (png_byte)bit_depth;
895 png_ptr->interlaced = (png_byte)interlace_type;
896 png_ptr->color_type = (png_byte)color_type;
897 #ifdef PNG_MNG_FEATURES_SUPPORTED
898 png_ptr->filter_type = (png_byte)filter_type;
899 #endif
900 png_ptr->compression_type = (png_byte)compression_type;
901
902 /* Find number of channels */
903 switch (png_ptr->color_type)
904 {
905 default: /* invalid, png_set_IHDR calls png_error */
906 case PNG_COLOR_TYPE_GRAY:
907 case PNG_COLOR_TYPE_PALETTE:
908 png_ptr->channels = 1;
909 break;
910
911 case PNG_COLOR_TYPE_RGB:
912 png_ptr->channels = 3;
913 break;
914
915 case PNG_COLOR_TYPE_GRAY_ALPHA:
916 png_ptr->channels = 2;
917 break;
918
919 case PNG_COLOR_TYPE_RGB_ALPHA:
920 png_ptr->channels = 4;
921 break;
922 }
923
924 /* Set up other useful info */
925 png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels);
926 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
927 png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
928 png_debug1(3, "channels = %d", png_ptr->channels);
929 png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
930 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
931 color_type, interlace_type, compression_type, filter_type);
932 }
933
934 /* Read and check the palette */
935 void /* PRIVATE */
936 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
937 {
938 png_color palette[PNG_MAX_PALETTE_LENGTH];
939 int max_palette_length, num, i;
940 #ifdef PNG_POINTER_INDEXING_SUPPORTED
941 png_colorp pal_ptr;
942 #endif
943
944 png_debug(1, "in png_handle_PLTE");
945
946 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
947 png_chunk_error(png_ptr, "missing IHDR");
948
949 /* Moved to before the 'after IDAT' check below because otherwise duplicate
950 * PLTE chunks are potentially ignored (the spec says there shall not be more
951 * than one PLTE, the error is not treated as benign, so this check trumps
952 * the requirement that PLTE appears before IDAT.)
953 */
954 else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
955 png_chunk_error(png_ptr, "duplicate");
956
957 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
958 {
959 /* This is benign because the non-benign error happened before, when an
960 * IDAT was encountered in a color-mapped image with no PLTE.
961 */
962 png_crc_finish(png_ptr, length);
963 png_chunk_benign_error(png_ptr, "out of place");
964 return;
965 }
966
967 png_ptr->mode |= PNG_HAVE_PLTE;
968
969 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
970 {
971 png_crc_finish(png_ptr, length);
972 png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
973 return;
974 }
975
976 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
977 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
978 {
979 png_crc_finish(png_ptr, length);
980 return;
981 }
982 #endif
983
984 if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
985 {
986 png_crc_finish(png_ptr, length);
987
988 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
989 png_chunk_benign_error(png_ptr, "invalid");
990
991 else
992 png_chunk_error(png_ptr, "invalid");
993
994 return;
995 }
996
997 /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
998 num = (int)length / 3;
999
1000 /* If the palette has 256 or fewer entries but is too large for the bit
1001 * depth, we don't issue an error, to preserve the behavior of previous
1002 * libpng versions. We silently truncate the unused extra palette entries
1003 * here.
1004 */
1005 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1006 max_palette_length = (1 << png_ptr->bit_depth);
1007 else
1008 max_palette_length = PNG_MAX_PALETTE_LENGTH;
1009
1010 if (num > max_palette_length)
1011 num = max_palette_length;
1012
1013 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1014 for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
1015 {
1016 png_byte buf[3];
1017
1018 png_crc_read(png_ptr, buf, 3);
1019 pal_ptr->red = buf[0];
1020 pal_ptr->green = buf[1];
1021 pal_ptr->blue = buf[2];
1022 }
1023 #else
1024 for (i = 0; i < num; i++)
1025 {
1026 png_byte buf[3];
1027
1028 png_crc_read(png_ptr, buf, 3);
1029 /* Don't depend upon png_color being any order */
1030 palette[i].red = buf[0];
1031 palette[i].green = buf[1];
1032 palette[i].blue = buf[2];
1033 }
1034 #endif
1035
1036 /* If we actually need the PLTE chunk (ie for a paletted image), we do
1037 * whatever the normal CRC configuration tells us. However, if we
1038 * have an RGB image, the PLTE can be considered ancillary, so
1039 * we will act as though it is.
1040 */
1041 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1042 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1043 #endif
1044 {
1045 png_crc_finish(png_ptr, (png_uint_32) (length - (unsigned int)num * 3));
1046 }
1047
1048 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1049 else if (png_crc_error(png_ptr) != 0) /* Only if we have a CRC error */
1050 {
1051 /* If we don't want to use the data from an ancillary chunk,
1052 * we have two options: an error abort, or a warning and we
1053 * ignore the data in this chunk (which should be OK, since
1054 * it's considered ancillary for a RGB or RGBA image).
1055 *
1056 * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
1057 * chunk type to determine whether to check the ancillary or the critical
1058 * flags.
1059 */
1060 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
1061 {
1062 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0)
1063 return;
1064
1065 else
1066 png_chunk_error(png_ptr, "CRC error");
1067 }
1068
1069 /* Otherwise, we (optionally) emit a warning and use the chunk. */
1070 else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
1071 png_chunk_warning(png_ptr, "CRC error");
1072 }
1073 #endif
1074
1075 /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
1076 * own copy of the palette. This has the side effect that when png_start_row
1077 * is called (this happens after any call to png_read_update_info) the
1078 * info_ptr palette gets changed. This is extremely unexpected and
1079 * confusing.
1080 *
1081 * Fix this by not sharing the palette in this way.
1082 */
1083 png_set_PLTE(png_ptr, info_ptr, palette, num);
1084
1085 /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
1086 * IDAT. Prior to 1.6.0 this was not checked; instead the code merely
1087 * checked the apparent validity of a tRNS chunk inserted before PLTE on a
1088 * palette PNG. 1.6.0 attempts to rigorously follow the standard and
1089 * therefore does a benign error if the erroneous condition is detected *and*
1090 * cancels the tRNS if the benign error returns. The alternative is to
1091 * amend the standard since it would be rather hypocritical of the standards
1092 * maintainers to ignore it.
1093 */
1094 #ifdef PNG_READ_tRNS_SUPPORTED
1095 if (png_ptr->num_trans > 0 ||
1096 (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
1097 {
1098 /* Cancel this because otherwise it would be used if the transforms
1099 * require it. Don't cancel the 'valid' flag because this would prevent
1100 * detection of duplicate chunks.
1101 */
1102 png_ptr->num_trans = 0;
1103
1104 if (info_ptr != NULL)
1105 info_ptr->num_trans = 0;
1106
1107 png_chunk_benign_error(png_ptr, "tRNS must be after");
1108 }
1109 #endif
1110
1111 #ifdef PNG_READ_hIST_SUPPORTED
1112 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
1113 png_chunk_benign_error(png_ptr, "hIST must be after");
1114 #endif
1115
1116 #ifdef PNG_READ_bKGD_SUPPORTED
1117 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1118 png_chunk_benign_error(png_ptr, "bKGD must be after");
1119 #endif
1120 }
1121
1122 void /* PRIVATE */
1123 png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1124 {
1125 png_debug(1, "in png_handle_IEND");
1126
1127 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0 ||
1128 (png_ptr->mode & PNG_HAVE_IDAT) == 0)
1129 png_chunk_error(png_ptr, "out of place");
1130
1131 png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
1132
1133 png_crc_finish(png_ptr, length);
1134
1135 if (length != 0)
1136 png_chunk_benign_error(png_ptr, "invalid");
1137
1138 PNG_UNUSED(info_ptr)
1139 }
1140
1141 #ifdef PNG_READ_gAMA_SUPPORTED
1142 void /* PRIVATE */
1143 png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1144 {
1145 png_fixed_point igamma;
1146 png_byte buf[4];
1147
1148 png_debug(1, "in png_handle_gAMA");
1149
1150 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1151 png_chunk_error(png_ptr, "missing IHDR");
1152
1153 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1154 {
1155 png_crc_finish(png_ptr, length);
1156 png_chunk_benign_error(png_ptr, "out of place");
1157 return;
1158 }
1159
1160 if (length != 4)
1161 {
1162 png_crc_finish(png_ptr, length);
1163 png_chunk_benign_error(png_ptr, "invalid");
1164 return;
1165 }
1166
1167 png_crc_read(png_ptr, buf, 4);
1168
1169 if (png_crc_finish(png_ptr, 0) != 0)
1170 return;
1171
1172 igamma = png_get_fixed_point(NULL, buf);
1173
1174 png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
1175 png_colorspace_sync(png_ptr, info_ptr);
1176 }
1177 #endif
1178
1179 #ifdef PNG_READ_sBIT_SUPPORTED
1180 void /* PRIVATE */
1181 png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1182 {
1183 unsigned int truelen, i;
1184 png_byte sample_depth;
1185 png_byte buf[4];
1186
1187 png_debug(1, "in png_handle_sBIT");
1188
1189 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1190 png_chunk_error(png_ptr, "missing IHDR");
1191
1192 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1193 {
1194 png_crc_finish(png_ptr, length);
1195 png_chunk_benign_error(png_ptr, "out of place");
1196 return;
1197 }
1198
1199 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT) != 0)
1200 {
1201 png_crc_finish(png_ptr, length);
1202 png_chunk_benign_error(png_ptr, "duplicate");
1203 return;
1204 }
1205
1206 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1207 {
1208 truelen = 3;
1209 sample_depth = 8;
1210 }
1211
1212 else
1213 {
1214 truelen = png_ptr->channels;
1215 sample_depth = png_ptr->bit_depth;
1216 }
1217
1218 if (length != truelen || length > 4)
1219 {
1220 png_chunk_benign_error(png_ptr, "invalid");
1221 png_crc_finish(png_ptr, length);
1222 return;
1223 }
1224
1225 buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
1226 png_crc_read(png_ptr, buf, truelen);
1227
1228 if (png_crc_finish(png_ptr, 0) != 0)
1229 return;
1230
1231 for (i=0; i<truelen; ++i)
1232 {
1233 if (buf[i] == 0 || buf[i] > sample_depth)
1234 {
1235 png_chunk_benign_error(png_ptr, "invalid");
1236 return;
1237 }
1238 }
1239
1240 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1241 {
1242 png_ptr->sig_bit.red = buf[0];
1243 png_ptr->sig_bit.green = buf[1];
1244 png_ptr->sig_bit.blue = buf[2];
1245 png_ptr->sig_bit.alpha = buf[3];
1246 }
1247
1248 else
1249 {
1250 png_ptr->sig_bit.gray = buf[0];
1251 png_ptr->sig_bit.red = buf[0];
1252 png_ptr->sig_bit.green = buf[0];
1253 png_ptr->sig_bit.blue = buf[0];
1254 png_ptr->sig_bit.alpha = buf[1];
1255 }
1256
1257 png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
1258 }
1259 #endif
1260
1261 #ifdef PNG_READ_cHRM_SUPPORTED
1262 void /* PRIVATE */
1263 png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1264 {
1265 png_byte buf[32];
1266 png_xy xy;
1267
1268 png_debug(1, "in png_handle_cHRM");
1269
1270 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1271 png_chunk_error(png_ptr, "missing IHDR");
1272
1273 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1274 {
1275 png_crc_finish(png_ptr, length);
1276 png_chunk_benign_error(png_ptr, "out of place");
1277 return;
1278 }
1279
1280 if (length != 32)
1281 {
1282 png_crc_finish(png_ptr, length);
1283 png_chunk_benign_error(png_ptr, "invalid");
1284 return;
1285 }
1286
1287 png_crc_read(png_ptr, buf, 32);
1288
1289 if (png_crc_finish(png_ptr, 0) != 0)
1290 return;
1291
1292 xy.whitex = png_get_fixed_point(NULL, buf);
1293 xy.whitey = png_get_fixed_point(NULL, buf + 4);
1294 xy.redx = png_get_fixed_point(NULL, buf + 8);
1295 xy.redy = png_get_fixed_point(NULL, buf + 12);
1296 xy.greenx = png_get_fixed_point(NULL, buf + 16);
1297 xy.greeny = png_get_fixed_point(NULL, buf + 20);
1298 xy.bluex = png_get_fixed_point(NULL, buf + 24);
1299 xy.bluey = png_get_fixed_point(NULL, buf + 28);
1300
1301 if (xy.whitex == PNG_FIXED_ERROR ||
1302 xy.whitey == PNG_FIXED_ERROR ||
1303 xy.redx == PNG_FIXED_ERROR ||
1304 xy.redy == PNG_FIXED_ERROR ||
1305 xy.greenx == PNG_FIXED_ERROR ||
1306 xy.greeny == PNG_FIXED_ERROR ||
1307 xy.bluex == PNG_FIXED_ERROR ||
1308 xy.bluey == PNG_FIXED_ERROR)
1309 {
1310 png_chunk_benign_error(png_ptr, "invalid values");
1311 return;
1312 }
1313
1314 /* If a colorspace error has already been output skip this chunk */
1315 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1316 return;
1317
1318 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0)
1319 {
1320 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1321 png_colorspace_sync(png_ptr, info_ptr);
1322 png_chunk_benign_error(png_ptr, "duplicate");
1323 return;
1324 }
1325
1326 png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
1327 (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1328 1/*prefer cHRM values*/);
1329 png_colorspace_sync(png_ptr, info_ptr);
1330 }
1331 #endif
1332
1333 #ifdef PNG_READ_sRGB_SUPPORTED
1334 void /* PRIVATE */
1335 png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1336 {
1337 png_byte intent;
1338
1339 png_debug(1, "in png_handle_sRGB");
1340
1341 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1342 png_chunk_error(png_ptr, "missing IHDR");
1343
1344 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1345 {
1346 png_crc_finish(png_ptr, length);
1347 png_chunk_benign_error(png_ptr, "out of place");
1348 return;
1349 }
1350
1351 if (length != 1)
1352 {
1353 png_crc_finish(png_ptr, length);
1354 png_chunk_benign_error(png_ptr, "invalid");
1355 return;
1356 }
1357
1358 png_crc_read(png_ptr, &intent, 1);
1359
1360 if (png_crc_finish(png_ptr, 0) != 0)
1361 return;
1362
1363 /* If a colorspace error has already been output skip this chunk */
1364 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1365 return;
1366
1367 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1368 * this.
1369 */
1370 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0)
1371 {
1372 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1373 png_colorspace_sync(png_ptr, info_ptr);
1374 png_chunk_benign_error(png_ptr, "too many profiles");
1375 return;
1376 }
1377
1378 (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
1379 png_colorspace_sync(png_ptr, info_ptr);
1380 }
1381 #endif /* READ_sRGB */
1382
1383 #ifdef PNG_READ_iCCP_SUPPORTED
1384 void /* PRIVATE */
1385 png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1386 /* Note: this does not properly handle profiles that are > 64K under DOS */
1387 {
1388 png_const_charp errmsg = NULL; /* error message output, or no error */
1389 int finished = 0; /* crc checked */
1390
1391 png_debug(1, "in png_handle_iCCP");
1392
1393 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1394 png_chunk_error(png_ptr, "missing IHDR");
1395
1396 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1397 {
1398 png_crc_finish(png_ptr, length);
1399 png_chunk_benign_error(png_ptr, "out of place");
1400 return;
1401 }
1402
1403 /* Consistent with all the above colorspace handling an obviously *invalid*
1404 * chunk is just ignored, so does not invalidate the color space. An
1405 * alternative is to set the 'invalid' flags at the start of this routine
1406 * and only clear them in they were not set before and all the tests pass.
1407 */
1408
1409 /* The keyword must be at least one character and there is a
1410 * terminator (0) byte and the compression method byte, and the
1411 * 'zlib' datastream is at least 11 bytes.
1412 */
1413 if (length < 14)
1414 {
1415 png_crc_finish(png_ptr, length);
1416 png_chunk_benign_error(png_ptr, "too short");
1417 return;
1418 }
1419
1420 /* If a colorspace error has already been output skip this chunk */
1421 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1422 {
1423 png_crc_finish(png_ptr, length);
1424 return;
1425 }
1426
1427 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1428 * this.
1429 */
1430 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
1431 {
1432 uInt read_length, keyword_length;
1433 char keyword[81];
1434
1435 /* Find the keyword; the keyword plus separator and compression method
1436 * bytes can be at most 81 characters long.
1437 */
1438 read_length = 81; /* maximum */
1439 if (read_length > length)
1440 read_length = (uInt)length;
1441
1442 png_crc_read(png_ptr, (png_bytep)keyword, read_length);
1443 length -= read_length;
1444
1445 /* The minimum 'zlib' stream is assumed to be just the 2 byte header,
1446 * 5 bytes minimum 'deflate' stream, and the 4 byte checksum.
1447 */
1448 if (length < 11)
1449 {
1450 png_crc_finish(png_ptr, length);
1451 png_chunk_benign_error(png_ptr, "too short");
1452 return;
1453 }
1454
1455 keyword_length = 0;
1456 while (keyword_length < 80 && keyword_length < read_length &&
1457 keyword[keyword_length] != 0)
1458 ++keyword_length;
1459
1460 /* TODO: make the keyword checking common */
1461 if (keyword_length >= 1 && keyword_length <= 79)
1462 {
1463 /* We only understand '0' compression - deflate - so if we get a
1464 * different value we can't safely decode the chunk.
1465 */
1466 if (keyword_length+1 < read_length &&
1467 keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
1468 {
1469 read_length -= keyword_length+2;
1470
1471 if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
1472 {
1473 Byte profile_header[132]={0};
1474 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
1475 png_alloc_size_t size = (sizeof profile_header);
1476
1477 png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
1478 png_ptr->zstream.avail_in = read_length;
1479 (void)png_inflate_read(png_ptr, local_buffer,
1480 (sizeof local_buffer), &length, profile_header, &size,
1481 0/*finish: don't, because the output is too small*/);
1482
1483 if (size == 0)
1484 {
1485 /* We have the ICC profile header; do the basic header checks.
1486 */
1487 png_uint_32 profile_length = png_get_uint_32(profile_header);
1488
1489 if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
1490 keyword, profile_length) != 0)
1491 {
1492 /* The length is apparently ok, so we can check the 132
1493 * byte header.
1494 */
1495 if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
1496 keyword, profile_length, profile_header,
1497 png_ptr->color_type) != 0)
1498 {
1499 /* Now read the tag table; a variable size buffer is
1500 * needed at this point, allocate one for the whole
1501 * profile. The header check has already validated
1502 * that none of this stuff will overflow.
1503 */
1504 png_uint_32 tag_count =
1505 png_get_uint_32(profile_header + 128);
1506 png_bytep profile = png_read_buffer(png_ptr,
1507 profile_length, 2/*silent*/);
1508
1509 if (profile != NULL)
1510 {
1511 memcpy(profile, profile_header,
1512 (sizeof profile_header));
1513
1514 size = 12 * tag_count;
1515
1516 (void)png_inflate_read(png_ptr, local_buffer,
1517 (sizeof local_buffer), &length,
1518 profile + (sizeof profile_header), &size, 0);
1519
1520 /* Still expect a buffer error because we expect
1521 * there to be some tag data!
1522 */
1523 if (size == 0)
1524 {
1525 if (png_icc_check_tag_table(png_ptr,
1526 &png_ptr->colorspace, keyword, profile_length,
1527 profile) != 0)
1528 {
1529 /* The profile has been validated for basic
1530 * security issues, so read the whole thing in.
1531 */
1532 size = profile_length - (sizeof profile_header)
1533 - 12 * tag_count;
1534
1535 (void)png_inflate_read(png_ptr, local_buffer,
1536 (sizeof local_buffer), &length,
1537 profile + (sizeof profile_header) +
1538 12 * tag_count, &size, 1/*finish*/);
1539
1540 if (length > 0 && !(png_ptr->flags &
1541 PNG_FLAG_BENIGN_ERRORS_WARN))
1542 errmsg = "extra compressed data";
1543
1544 /* But otherwise allow extra data: */
1545 else if (size == 0)
1546 {
1547 if (length > 0)
1548 {
1549 /* This can be handled completely, so
1550 * keep going.
1551 */
1552 png_chunk_warning(png_ptr,
1553 "extra compressed data");
1554 }
1555
1556 png_crc_finish(png_ptr, length);
1557 finished = 1;
1558
1559 # if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
1560 /* Check for a match against sRGB */
1561 png_icc_set_sRGB(png_ptr,
1562 &png_ptr->colorspace, profile,
1563 png_ptr->zstream.adler);
1564 # endif
1565
1566 /* Steal the profile for info_ptr. */
1567 if (info_ptr != NULL)
1568 {
1569 png_free_data(png_ptr, info_ptr,
1570 PNG_FREE_ICCP, 0);
1571
1572 info_ptr->iccp_name = png_voidcast(char*,
1573 png_malloc_base(png_ptr,
1574 keyword_length+1));
1575 if (info_ptr->iccp_name != NULL)
1576 {
1577 memcpy(info_ptr->iccp_name, keyword,
1578 keyword_length+1);
1579 info_ptr->iccp_proflen =
1580 profile_length;
1581 info_ptr->iccp_profile = profile;
1582 png_ptr->read_buffer = NULL; /*steal*/
1583 info_ptr->free_me |= PNG_FREE_ICCP;
1584 info_ptr->valid |= PNG_INFO_iCCP;
1585 }
1586
1587 else
1588 {
1589 png_ptr->colorspace.flags |=
1590 PNG_COLORSPACE_INVALID;
1591 errmsg = "out of memory";
1592 }
1593 }
1594
1595 /* else the profile remains in the read
1596 * buffer which gets reused for subsequent
1597 * chunks.
1598 */
1599
1600 if (info_ptr != NULL)
1601 png_colorspace_sync(png_ptr, info_ptr);
1602
1603 if (errmsg == NULL)
1604 {
1605 png_ptr->zowner = 0;
1606 return;
1607 }
1608 }
1609 if (errmsg == NULL)
1610 errmsg = png_ptr->zstream.msg;
1611 }
1612 /* else png_icc_check_tag_table output an error */
1613 }
1614 else /* profile truncated */
1615 errmsg = png_ptr->zstream.msg;
1616 }
1617
1618 else
1619 errmsg = "out of memory";
1620 }
1621
1622 /* else png_icc_check_header output an error */
1623 }
1624
1625 /* else png_icc_check_length output an error */
1626 }
1627
1628 else /* profile truncated */
1629 errmsg = png_ptr->zstream.msg;
1630
1631 /* Release the stream */
1632 png_ptr->zowner = 0;
1633 }
1634
1635 else /* png_inflate_claim failed */
1636 errmsg = png_ptr->zstream.msg;
1637 }
1638
1639 else
1640 errmsg = "bad compression method"; /* or missing */
1641 }
1642
1643 else
1644 errmsg = "bad keyword";
1645 }
1646
1647 else
1648 errmsg = "too many profiles";
1649
1650 /* Failure: the reason is in 'errmsg' */
1651 if (finished == 0)
1652 png_crc_finish(png_ptr, length);
1653
1654 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1655 png_colorspace_sync(png_ptr, info_ptr);
1656 if (errmsg != NULL) /* else already output */
1657 png_chunk_benign_error(png_ptr, errmsg);
1658 }
1659 #endif /* READ_iCCP */
1660
1661 #ifdef PNG_READ_sPLT_SUPPORTED
1662 void /* PRIVATE */
1663 png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1664 /* Note: this does not properly handle chunks that are > 64K under DOS */
1665 {
1666 png_bytep entry_start, buffer;
1667 png_sPLT_t new_palette;
1668 png_sPLT_entryp pp;
1669 png_uint_32 data_length;
1670 int entry_size, i;
1671 png_uint_32 skip = 0;
1672 png_uint_32 dl;
1673 size_t max_dl;
1674
1675 png_debug(1, "in png_handle_sPLT");
1676
1677 #ifdef PNG_USER_LIMITS_SUPPORTED
1678 if (png_ptr->user_chunk_cache_max != 0)
1679 {
1680 if (png_ptr->user_chunk_cache_max == 1)
1681 {
1682 png_crc_finish(png_ptr, length);
1683 return;
1684 }
1685
1686 if (--png_ptr->user_chunk_cache_max == 1)
1687 {
1688 png_warning(png_ptr, "No space in chunk cache for sPLT");
1689 png_crc_finish(png_ptr, length);
1690 return;
1691 }
1692 }
1693 #endif
1694
1695 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1696 png_chunk_error(png_ptr, "missing IHDR");
1697
1698 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
1699 {
1700 png_crc_finish(png_ptr, length);
1701 png_chunk_benign_error(png_ptr, "out of place");
1702 return;
1703 }
1704
1705 #ifdef PNG_MAX_MALLOC_64K
1706 if (length > 65535U)
1707 {
1708 png_crc_finish(png_ptr, length);
1709 png_chunk_benign_error(png_ptr, "too large to fit in memory");
1710 return;
1711 }
1712 #endif
1713
1714 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
1715 if (buffer == NULL)
1716 {
1717 png_crc_finish(png_ptr, length);
1718 png_chunk_benign_error(png_ptr, "out of memory");
1719 return;
1720 }
1721
1722
1723 /* WARNING: this may break if size_t is less than 32 bits; it is assumed
1724 * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
1725 * potential breakage point if the types in pngconf.h aren't exactly right.
1726 */
1727 png_crc_read(png_ptr, buffer, length);
1728
1729 if (png_crc_finish(png_ptr, skip) != 0)
1730 return;
1731
1732 buffer[length] = 0;
1733
1734 for (entry_start = buffer; *entry_start; entry_start++)
1735 /* Empty loop to find end of name */ ;
1736
1737 ++entry_start;
1738
1739 /* A sample depth should follow the separator, and we should be on it */
1740 if (length < 2U || entry_start > buffer + (length - 2U))
1741 {
1742 png_warning(png_ptr, "malformed sPLT chunk");
1743 return;
1744 }
1745
1746 new_palette.depth = *entry_start++;
1747 entry_size = (new_palette.depth == 8 ? 6 : 10);
1748 /* This must fit in a png_uint_32 because it is derived from the original
1749 * chunk data length.
1750 */
1751 data_length = length - (png_uint_32)(entry_start - buffer);
1752
1753 /* Integrity-check the data length */
1754 if ((data_length % (unsigned int)entry_size) != 0)
1755 {
1756 png_warning(png_ptr, "sPLT chunk has bad length");
1757 return;
1758 }
1759
1760 dl = (png_uint_32)(data_length / (unsigned int)entry_size);
1761 max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
1762
1763 if (dl > max_dl)
1764 {
1765 png_warning(png_ptr, "sPLT chunk too long");
1766 return;
1767 }
1768
1769 new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size);
1770
1771 new_palette.entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
1772 (png_alloc_size_t) new_palette.nentries * (sizeof (png_sPLT_entry)));
1773
1774 if (new_palette.entries == NULL)
1775 {
1776 png_warning(png_ptr, "sPLT chunk requires too much memory");
1777 return;
1778 }
1779
1780 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1781 for (i = 0; i < new_palette.nentries; i++)
1782 {
1783 pp = new_palette.entries + i;
1784
1785 if (new_palette.depth == 8)
1786 {
1787 pp->red = *entry_start++;
1788 pp->green = *entry_start++;
1789 pp->blue = *entry_start++;
1790 pp->alpha = *entry_start++;
1791 }
1792
1793 else
1794 {
1795 pp->red = png_get_uint_16(entry_start); entry_start += 2;
1796 pp->green = png_get_uint_16(entry_start); entry_start += 2;
1797 pp->blue = png_get_uint_16(entry_start); entry_start += 2;
1798 pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
1799 }
1800
1801 pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
1802 }
1803 #else
1804 pp = new_palette.entries;
1805
1806 for (i = 0; i < new_palette.nentries; i++)
1807 {
1808
1809 if (new_palette.depth == 8)
1810 {
1811 pp[i].red = *entry_start++;
1812 pp[i].green = *entry_start++;
1813 pp[i].blue = *entry_start++;
1814 pp[i].alpha = *entry_start++;
1815 }
1816
1817 else
1818 {
1819 pp[i].red = png_get_uint_16(entry_start); entry_start += 2;
1820 pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
1821 pp[i].blue = png_get_uint_16(entry_start); entry_start += 2;
1822 pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
1823 }
1824
1825 pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
1826 }
1827 #endif
1828
1829 /* Discard all chunk data except the name and stash that */
1830 new_palette.name = (png_charp)buffer;
1831
1832 png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
1833
1834 png_free(png_ptr, new_palette.entries);
1835 }
1836 #endif /* READ_sPLT */
1837
1838 #ifdef PNG_READ_tRNS_SUPPORTED
1839 void /* PRIVATE */
1840 png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1841 {
1842 png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
1843
1844 png_debug(1, "in png_handle_tRNS");
1845
1846 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1847 png_chunk_error(png_ptr, "missing IHDR");
1848
1849 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
1850 {
1851 png_crc_finish(png_ptr, length);
1852 png_chunk_benign_error(png_ptr, "out of place");
1853 return;
1854 }
1855
1856 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)
1857 {
1858 png_crc_finish(png_ptr, length);
1859 png_chunk_benign_error(png_ptr, "duplicate");
1860 return;
1861 }
1862
1863 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
1864 {
1865 png_byte buf[2];
1866
1867 if (length != 2)
1868 {
1869 png_crc_finish(png_ptr, length);
1870 png_chunk_benign_error(png_ptr, "invalid");
1871 return;
1872 }
1873
1874 png_crc_read(png_ptr, buf, 2);
1875 png_ptr->num_trans = 1;
1876 png_ptr->trans_color.gray = png_get_uint_16(buf);
1877 }
1878
1879 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
1880 {
1881 png_byte buf[6];
1882
1883 if (length != 6)
1884 {
1885 png_crc_finish(png_ptr, length);
1886 png_chunk_benign_error(png_ptr, "invalid");
1887 return;
1888 }
1889
1890 png_crc_read(png_ptr, buf, length);
1891 png_ptr->num_trans = 1;
1892 png_ptr->trans_color.red = png_get_uint_16(buf);
1893 png_ptr->trans_color.green = png_get_uint_16(buf + 2);
1894 png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
1895 }
1896
1897 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1898 {
1899 if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
1900 {
1901 /* TODO: is this actually an error in the ISO spec? */
1902 png_crc_finish(png_ptr, length);
1903 png_chunk_benign_error(png_ptr, "out of place");
1904 return;
1905 }
1906
1907 if (length > (unsigned int) png_ptr->num_palette ||
1908 length > (unsigned int) PNG_MAX_PALETTE_LENGTH ||
1909 length == 0)
1910 {
1911 png_crc_finish(png_ptr, length);
1912 png_chunk_benign_error(png_ptr, "invalid");
1913 return;
1914 }
1915
1916 png_crc_read(png_ptr, readbuf, length);
1917 png_ptr->num_trans = (png_uint_16)length;
1918 }
1919
1920 else
1921 {
1922 png_crc_finish(png_ptr, length);
1923 png_chunk_benign_error(png_ptr, "invalid with alpha channel");
1924 return;
1925 }
1926
1927 if (png_crc_finish(png_ptr, 0) != 0)
1928 {
1929 png_ptr->num_trans = 0;
1930 return;
1931 }
1932
1933 /* TODO: this is a horrible side effect in the palette case because the
1934 * png_struct ends up with a pointer to the tRNS buffer owned by the
1935 * png_info. Fix this.
1936 */
1937 png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
1938 &(png_ptr->trans_color));
1939 }
1940 #endif
1941
1942 #ifdef PNG_READ_bKGD_SUPPORTED
1943 void /* PRIVATE */
1944 png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1945 {
1946 unsigned int truelen;
1947 png_byte buf[6];
1948 png_color_16 background;
1949
1950 png_debug(1, "in png_handle_bKGD");
1951
1952 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1953 png_chunk_error(png_ptr, "missing IHDR");
1954
1955 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
1956 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
1957 (png_ptr->mode & PNG_HAVE_PLTE) == 0))
1958 {
1959 png_crc_finish(png_ptr, length);
1960 png_chunk_benign_error(png_ptr, "out of place");
1961 return;
1962 }
1963
1964 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1965 {
1966 png_crc_finish(png_ptr, length);
1967 png_chunk_benign_error(png_ptr, "duplicate");
1968 return;
1969 }
1970
1971 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1972 truelen = 1;
1973
1974 else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1975 truelen = 6;
1976
1977 else
1978 truelen = 2;
1979
1980 if (length != truelen)
1981 {
1982 png_crc_finish(png_ptr, length);
1983 png_chunk_benign_error(png_ptr, "invalid");
1984 return;
1985 }
1986
1987 png_crc_read(png_ptr, buf, truelen);
1988
1989 if (png_crc_finish(png_ptr, 0) != 0)
1990 return;
1991
1992 /* We convert the index value into RGB components so that we can allow
1993 * arbitrary RGB values for background when we have transparency, and
1994 * so it is easy to determine the RGB values of the background color
1995 * from the info_ptr struct.
1996 */
1997 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1998 {
1999 background.index = buf[0];
2000
2001 if (info_ptr != NULL && info_ptr->num_palette != 0)
2002 {
2003 if (buf[0] >= info_ptr->num_palette)
2004 {
2005 png_chunk_benign_error(png_ptr, "invalid index");
2006 return;
2007 }
2008
2009 background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
2010 background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
2011 background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
2012 }
2013
2014 else
2015 background.red = background.green = background.blue = 0;
2016
2017 background.gray = 0;
2018 }
2019
2020 else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
2021 {
2022 if (png_ptr->bit_depth <= 8)
2023 {
2024 if (buf[0] != 0 || buf[1] >= (unsigned int)(1 << png_ptr->bit_depth))
2025 {
2026 png_chunk_benign_error(png_ptr, "invalid gray level");
2027 return;
2028 }
2029 }
2030
2031 background.index = 0;
2032 background.red =
2033 background.green =
2034 background.blue =
2035 background.gray = png_get_uint_16(buf);
2036 }
2037
2038 else
2039 {
2040 if (png_ptr->bit_depth <= 8)
2041 {
2042 if (buf[0] != 0 || buf[2] != 0 || buf[4] != 0)
2043 {
2044 png_chunk_benign_error(png_ptr, "invalid color");
2045 return;
2046 }
2047 }
2048
2049 background.index = 0;
2050 background.red = png_get_uint_16(buf);
2051 background.green = png_get_uint_16(buf + 2);
2052 background.blue = png_get_uint_16(buf + 4);
2053 background.gray = 0;
2054 }
2055
2056 png_set_bKGD(png_ptr, info_ptr, &background);
2057 }
2058 #endif
2059
2060 #ifdef PNG_READ_eXIf_SUPPORTED
2061 void /* PRIVATE */
2062 png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2063 {
2064 unsigned int i;
2065
2066 png_debug(1, "in png_handle_eXIf");
2067
2068 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2069 png_chunk_error(png_ptr, "missing IHDR");
2070
2071 if (length < 2)
2072 {
2073 png_crc_finish(png_ptr, length);
2074 png_chunk_benign_error(png_ptr, "too short");
2075 return;
2076 }
2077
2078 else if (info_ptr == NULL || (info_ptr->valid & PNG_INFO_eXIf) != 0)
2079 {
2080 png_crc_finish(png_ptr, length);
2081 png_chunk_benign_error(png_ptr, "duplicate");
2082 return;
2083 }
2084
2085 info_ptr->free_me |= PNG_FREE_EXIF;
2086
2087 info_ptr->eXIf_buf = png_voidcast(png_bytep,
2088 png_malloc_warn(png_ptr, length));
2089
2090 if (info_ptr->eXIf_buf == NULL)
2091 {
2092 png_crc_finish(png_ptr, length);
2093 png_chunk_benign_error(png_ptr, "out of memory");
2094 return;
2095 }
2096
2097 for (i = 0; i < length; i++)
2098 {
2099 png_byte buf[1];
2100 png_crc_read(png_ptr, buf, 1);
2101 info_ptr->eXIf_buf[i] = buf[0];
2102 if (i == 1 && buf[0] != 'M' && buf[0] != 'I'
2103 && info_ptr->eXIf_buf[0] != buf[0])
2104 {
2105 png_crc_finish(png_ptr, length);
2106 png_chunk_benign_error(png_ptr, "incorrect byte-order specifier");
2107 png_free(png_ptr, info_ptr->eXIf_buf);
2108 info_ptr->eXIf_buf = NULL;
2109 return;
2110 }
2111 }
2112
2113 if (png_crc_finish(png_ptr, 0) != 0)
2114 return;
2115
2116 png_set_eXIf_1(png_ptr, info_ptr, length, info_ptr->eXIf_buf);
2117
2118 png_free(png_ptr, info_ptr->eXIf_buf);
2119 info_ptr->eXIf_buf = NULL;
2120 }
2121 #endif
2122
2123 #ifdef PNG_READ_hIST_SUPPORTED
2124 void /* PRIVATE */
2125 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2126 {
2127 unsigned int num, i;
2128 png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
2129
2130 png_debug(1, "in png_handle_hIST");
2131
2132 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2133 png_chunk_error(png_ptr, "missing IHDR");
2134
2135 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
2136 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
2137 {
2138 png_crc_finish(png_ptr, length);
2139 png_chunk_benign_error(png_ptr, "out of place");
2140 return;
2141 }
2142
2143 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
2144 {
2145 png_crc_finish(png_ptr, length);
2146 png_chunk_benign_error(png_ptr, "duplicate");
2147 return;
2148 }
2149
2150 num = length / 2 ;
2151
2152 if (num != (unsigned int) png_ptr->num_palette ||
2153 num > (unsigned int) PNG_MAX_PALETTE_LENGTH)
2154 {
2155 png_crc_finish(png_ptr, length);
2156 png_chunk_benign_error(png_ptr, "invalid");
2157 return;
2158 }
2159
2160 for (i = 0; i < num; i++)
2161 {
2162 png_byte buf[2];
2163
2164 png_crc_read(png_ptr, buf, 2);
2165 readbuf[i] = png_get_uint_16(buf);
2166 }
2167
2168 if (png_crc_finish(png_ptr, 0) != 0)
2169 return;
2170
2171 png_set_hIST(png_ptr, info_ptr, readbuf);
2172 }
2173 #endif
2174
2175 #ifdef PNG_READ_pHYs_SUPPORTED
2176 void /* PRIVATE */
2177 png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2178 {
2179 png_byte buf[9];
2180 png_uint_32 res_x, res_y;
2181 int unit_type;
2182
2183 png_debug(1, "in png_handle_pHYs");
2184
2185 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2186 png_chunk_error(png_ptr, "missing IHDR");
2187
2188 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2189 {
2190 png_crc_finish(png_ptr, length);
2191 png_chunk_benign_error(png_ptr, "out of place");
2192 return;
2193 }
2194
2195 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs) != 0)
2196 {
2197 png_crc_finish(png_ptr, length);
2198 png_chunk_benign_error(png_ptr, "duplicate");
2199 return;
2200 }
2201
2202 if (length != 9)
2203 {
2204 png_crc_finish(png_ptr, length);
2205 png_chunk_benign_error(png_ptr, "invalid");
2206 return;
2207 }
2208
2209 png_crc_read(png_ptr, buf, 9);
2210
2211 if (png_crc_finish(png_ptr, 0) != 0)
2212 return;
2213
2214 res_x = png_get_uint_32(buf);
2215 res_y = png_get_uint_32(buf + 4);
2216 unit_type = buf[8];
2217 png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
2218 }
2219 #endif
2220
2221 #ifdef PNG_READ_oFFs_SUPPORTED
2222 void /* PRIVATE */
2223 png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2224 {
2225 png_byte buf[9];
2226 png_int_32 offset_x, offset_y;
2227 int unit_type;
2228
2229 png_debug(1, "in png_handle_oFFs");
2230
2231 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2232 png_chunk_error(png_ptr, "missing IHDR");
2233
2234 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2235 {
2236 png_crc_finish(png_ptr, length);
2237 png_chunk_benign_error(png_ptr, "out of place");
2238 return;
2239 }
2240
2241 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs) != 0)
2242 {
2243 png_crc_finish(png_ptr, length);
2244 png_chunk_benign_error(png_ptr, "duplicate");
2245 return;
2246 }
2247
2248 if (length != 9)
2249 {
2250 png_crc_finish(png_ptr, length);
2251 png_chunk_benign_error(png_ptr, "invalid");
2252 return;
2253 }
2254
2255 png_crc_read(png_ptr, buf, 9);
2256
2257 if (png_crc_finish(png_ptr, 0) != 0)
2258 return;
2259
2260 offset_x = png_get_int_32(buf);
2261 offset_y = png_get_int_32(buf + 4);
2262 unit_type = buf[8];
2263 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
2264 }
2265 #endif
2266
2267 #ifdef PNG_READ_pCAL_SUPPORTED
2268 /* Read the pCAL chunk (described in the PNG Extensions document) */
2269 void /* PRIVATE */
2270 png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2271 {
2272 png_int_32 X0, X1;
2273 png_byte type, nparams;
2274 png_bytep buffer, buf, units, endptr;
2275 png_charpp params;
2276 int i;
2277
2278 png_debug(1, "in png_handle_pCAL");
2279
2280 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2281 png_chunk_error(png_ptr, "missing IHDR");
2282
2283 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2284 {
2285 png_crc_finish(png_ptr, length);
2286 png_chunk_benign_error(png_ptr, "out of place");
2287 return;
2288 }
2289
2290 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL) != 0)
2291 {
2292 png_crc_finish(png_ptr, length);
2293 png_chunk_benign_error(png_ptr, "duplicate");
2294 return;
2295 }
2296
2297 png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
2298 length + 1);
2299
2300 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2301
2302 if (buffer == NULL)
2303 {
2304 png_crc_finish(png_ptr, length);
2305 png_chunk_benign_error(png_ptr, "out of memory");
2306 return;
2307 }
2308
2309 png_crc_read(png_ptr, buffer, length);
2310
2311 if (png_crc_finish(png_ptr, 0) != 0)
2312 return;
2313
2314 buffer[length] = 0; /* Null terminate the last string */
2315
2316 png_debug(3, "Finding end of pCAL purpose string");
2317 for (buf = buffer; *buf; buf++)
2318 /* Empty loop */ ;
2319
2320 endptr = buffer + length;
2321
2322 /* We need to have at least 12 bytes after the purpose string
2323 * in order to get the parameter information.
2324 */
2325 if (endptr - buf <= 12)
2326 {
2327 png_chunk_benign_error(png_ptr, "invalid");
2328 return;
2329 }
2330
2331 png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
2332 X0 = png_get_int_32((png_bytep)buf+1);
2333 X1 = png_get_int_32((png_bytep)buf+5);
2334 type = buf[9];
2335 nparams = buf[10];
2336 units = buf + 11;
2337
2338 png_debug(3, "Checking pCAL equation type and number of parameters");
2339 /* Check that we have the right number of parameters for known
2340 * equation types.
2341 */
2342 if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
2343 (type == PNG_EQUATION_BASE_E && nparams != 3) ||
2344 (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
2345 (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
2346 {
2347 png_chunk_benign_error(png_ptr, "invalid parameter count");
2348 return;
2349 }
2350
2351 else if (type >= PNG_EQUATION_LAST)
2352 {
2353 png_chunk_benign_error(png_ptr, "unrecognized equation type");
2354 }
2355
2356 for (buf = units; *buf; buf++)
2357 /* Empty loop to move past the units string. */ ;
2358
2359 png_debug(3, "Allocating pCAL parameters array");
2360
2361 params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
2362 nparams * (sizeof (png_charp))));
2363
2364 if (params == NULL)
2365 {
2366 png_chunk_benign_error(png_ptr, "out of memory");
2367 return;
2368 }
2369
2370 /* Get pointers to the start of each parameter string. */
2371 for (i = 0; i < nparams; i++)
2372 {
2373 buf++; /* Skip the null string terminator from previous parameter. */
2374
2375 png_debug1(3, "Reading pCAL parameter %d", i);
2376
2377 for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
2378 /* Empty loop to move past each parameter string */ ;
2379
2380 /* Make sure we haven't run out of data yet */
2381 if (buf > endptr)
2382 {
2383 png_free(png_ptr, params);
2384 png_chunk_benign_error(png_ptr, "invalid data");
2385 return;
2386 }
2387 }
2388
2389 png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
2390 (png_charp)units, params);
2391
2392 png_free(png_ptr, params);
2393 }
2394 #endif
2395
2396 #ifdef PNG_READ_sCAL_SUPPORTED
2397 /* Read the sCAL chunk */
2398 void /* PRIVATE */
2399 png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2400 {
2401 png_bytep buffer;
2402 size_t i;
2403 int state;
2404
2405 png_debug(1, "in png_handle_sCAL");
2406
2407 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2408 png_chunk_error(png_ptr, "missing IHDR");
2409
2410 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2411 {
2412 png_crc_finish(png_ptr, length);
2413 png_chunk_benign_error(png_ptr, "out of place");
2414 return;
2415 }
2416
2417 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL) != 0)
2418 {
2419 png_crc_finish(png_ptr, length);
2420 png_chunk_benign_error(png_ptr, "duplicate");
2421 return;
2422 }
2423
2424 /* Need unit type, width, \0, height: minimum 4 bytes */
2425 else if (length < 4)
2426 {
2427 png_crc_finish(png_ptr, length);
2428 png_chunk_benign_error(png_ptr, "invalid");
2429 return;
2430 }
2431
2432 png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
2433 length + 1);
2434
2435 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2436
2437 if (buffer == NULL)
2438 {
2439 png_chunk_benign_error(png_ptr, "out of memory");
2440 png_crc_finish(png_ptr, length);
2441 return;
2442 }
2443
2444 png_crc_read(png_ptr, buffer, length);
2445 buffer[length] = 0; /* Null terminate the last string */
2446
2447 if (png_crc_finish(png_ptr, 0) != 0)
2448 return;
2449
2450 /* Validate the unit. */
2451 if (buffer[0] != 1 && buffer[0] != 2)
2452 {
2453 png_chunk_benign_error(png_ptr, "invalid unit");
2454 return;
2455 }
2456
2457 /* Validate the ASCII numbers, need two ASCII numbers separated by
2458 * a '\0' and they need to fit exactly in the chunk data.
2459 */
2460 i = 1;
2461 state = 0;
2462
2463 if (png_check_fp_number((png_const_charp)buffer, length, &state, &i) == 0 ||
2464 i >= length || buffer[i++] != 0)
2465 png_chunk_benign_error(png_ptr, "bad width format");
2466
2467 else if (PNG_FP_IS_POSITIVE(state) == 0)
2468 png_chunk_benign_error(png_ptr, "non-positive width");
2469
2470 else
2471 {
2472 size_t heighti = i;
2473
2474 state = 0;
2475 if (png_check_fp_number((png_const_charp)buffer, length,
2476 &state, &i) == 0 || i != length)
2477 png_chunk_benign_error(png_ptr, "bad height format");
2478
2479 else if (PNG_FP_IS_POSITIVE(state) == 0)
2480 png_chunk_benign_error(png_ptr, "non-positive height");
2481
2482 else
2483 /* This is the (only) success case. */
2484 png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
2485 (png_charp)buffer+1, (png_charp)buffer+heighti);
2486 }
2487 }
2488 #endif
2489
2490 #ifdef PNG_READ_tIME_SUPPORTED
2491 void /* PRIVATE */
2492 png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2493 {
2494 png_byte buf[7];
2495 png_time mod_time;
2496
2497 png_debug(1, "in png_handle_tIME");
2498
2499 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2500 png_chunk_error(png_ptr, "missing IHDR");
2501
2502 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME) != 0)
2503 {
2504 png_crc_finish(png_ptr, length);
2505 png_chunk_benign_error(png_ptr, "duplicate");
2506 return;
2507 }
2508
2509 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2510 png_ptr->mode |= PNG_AFTER_IDAT;
2511
2512 if (length != 7)
2513 {
2514 png_crc_finish(png_ptr, length);
2515 png_chunk_benign_error(png_ptr, "invalid");
2516 return;
2517 }
2518
2519 png_crc_read(png_ptr, buf, 7);
2520
2521 if (png_crc_finish(png_ptr, 0) != 0)
2522 return;
2523
2524 mod_time.second = buf[6];
2525 mod_time.minute = buf[5];
2526 mod_time.hour = buf[4];
2527 mod_time.day = buf[3];
2528 mod_time.month = buf[2];
2529 mod_time.year = png_get_uint_16(buf);
2530
2531 png_set_tIME(png_ptr, info_ptr, &mod_time);
2532 }
2533 #endif
2534
2535 #ifdef PNG_READ_tEXt_SUPPORTED
2536 /* Note: this does not properly handle chunks that are > 64K under DOS */
2537 void /* PRIVATE */
2538 png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2539 {
2540 png_text text_info;
2541 png_bytep buffer;
2542 png_charp key;
2543 png_charp text;
2544 png_uint_32 skip = 0;
2545
2546 png_debug(1, "in png_handle_tEXt");
2547
2548 #ifdef PNG_USER_LIMITS_SUPPORTED
2549 if (png_ptr->user_chunk_cache_max != 0)
2550 {
2551 if (png_ptr->user_chunk_cache_max == 1)
2552 {
2553 png_crc_finish(png_ptr, length);
2554 return;
2555 }
2556
2557 if (--png_ptr->user_chunk_cache_max == 1)
2558 {
2559 png_crc_finish(png_ptr, length);
2560 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2561 return;
2562 }
2563 }
2564 #endif
2565
2566 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2567 png_chunk_error(png_ptr, "missing IHDR");
2568
2569 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2570 png_ptr->mode |= PNG_AFTER_IDAT;
2571
2572 #ifdef PNG_MAX_MALLOC_64K
2573 if (length > 65535U)
2574 {
2575 png_crc_finish(png_ptr, length);
2576 png_chunk_benign_error(png_ptr, "too large to fit in memory");
2577 return;
2578 }
2579 #endif
2580
2581 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2582
2583 if (buffer == NULL)
2584 {
2585 png_chunk_benign_error(png_ptr, "out of memory");
2586 return;
2587 }
2588
2589 png_crc_read(png_ptr, buffer, length);
2590
2591 if (png_crc_finish(png_ptr, skip) != 0)
2592 return;
2593
2594 key = (png_charp)buffer;
2595 key[length] = 0;
2596
2597 for (text = key; *text; text++)
2598 /* Empty loop to find end of key */ ;
2599
2600 if (text != key + length)
2601 text++;
2602
2603 text_info.compression = PNG_TEXT_COMPRESSION_NONE;
2604 text_info.key = key;
2605 text_info.lang = NULL;
2606 text_info.lang_key = NULL;
2607 text_info.itxt_length = 0;
2608 text_info.text = text;
2609 text_info.text_length = strlen(text);
2610
2611 if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) != 0)
2612 png_warning(png_ptr, "Insufficient memory to process text chunk");
2613 }
2614 #endif
2615
2616 #ifdef PNG_READ_zTXt_SUPPORTED
2617 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2618 void /* PRIVATE */
2619 png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2620 {
2621 png_const_charp errmsg = NULL;
2622 png_bytep buffer;
2623 png_uint_32 keyword_length;
2624
2625 png_debug(1, "in png_handle_zTXt");
2626
2627 #ifdef PNG_USER_LIMITS_SUPPORTED
2628 if (png_ptr->user_chunk_cache_max != 0)
2629 {
2630 if (png_ptr->user_chunk_cache_max == 1)
2631 {
2632 png_crc_finish(png_ptr, length);
2633 return;
2634 }
2635
2636 if (--png_ptr->user_chunk_cache_max == 1)
2637 {
2638 png_crc_finish(png_ptr, length);
2639 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2640 return;
2641 }
2642 }
2643 #endif
2644
2645 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2646 png_chunk_error(png_ptr, "missing IHDR");
2647
2648 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2649 png_ptr->mode |= PNG_AFTER_IDAT;
2650
2651 /* Note, "length" is sufficient here; we won't be adding
2652 * a null terminator later.
2653 */
2654 buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
2655
2656 if (buffer == NULL)
2657 {
2658 png_crc_finish(png_ptr, length);
2659 png_chunk_benign_error(png_ptr, "out of memory");
2660 return;
2661 }
2662
2663 png_crc_read(png_ptr, buffer, length);
2664
2665 if (png_crc_finish(png_ptr, 0) != 0)
2666 return;
2667
2668 /* TODO: also check that the keyword contents match the spec! */
2669 for (keyword_length = 0;
2670 keyword_length < length && buffer[keyword_length] != 0;
2671 ++keyword_length)
2672 /* Empty loop to find end of name */ ;
2673
2674 if (keyword_length > 79 || keyword_length < 1)
2675 errmsg = "bad keyword";
2676
2677 /* zTXt must have some LZ data after the keyword, although it may expand to
2678 * zero bytes; we need a '\0' at the end of the keyword, the compression type
2679 * then the LZ data:
2680 */
2681 else if (keyword_length + 3 > length)
2682 errmsg = "truncated";
2683
2684 else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
2685 errmsg = "unknown compression type";
2686
2687 else
2688 {
2689 png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
2690
2691 /* TODO: at present png_decompress_chunk imposes a single application
2692 * level memory limit, this should be split to different values for iCCP
2693 * and text chunks.
2694 */
2695 if (png_decompress_chunk(png_ptr, length, keyword_length+2,
2696 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2697 {
2698 png_text text;
2699
2700 if (png_ptr->read_buffer == NULL)
2701 errmsg="Read failure in png_handle_zTXt";
2702 else
2703 {
2704 /* It worked; png_ptr->read_buffer now looks like a tEXt chunk
2705 * except for the extra compression type byte and the fact that
2706 * it isn't necessarily '\0' terminated.
2707 */
2708 buffer = png_ptr->read_buffer;
2709 buffer[uncompressed_length+(keyword_length+2)] = 0;
2710
2711 text.compression = PNG_TEXT_COMPRESSION_zTXt;
2712 text.key = (png_charp)buffer;
2713 text.text = (png_charp)(buffer + keyword_length+2);
2714 text.text_length = uncompressed_length;
2715 text.itxt_length = 0;
2716 text.lang = NULL;
2717 text.lang_key = NULL;
2718
2719 if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
2720 errmsg = "insufficient memory";
2721 }
2722 }
2723
2724 else
2725 errmsg = png_ptr->zstream.msg;
2726 }
2727
2728 if (errmsg != NULL)
2729 png_chunk_benign_error(png_ptr, errmsg);
2730 }
2731 #endif
2732
2733 #ifdef PNG_READ_iTXt_SUPPORTED
2734 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2735 void /* PRIVATE */
2736 png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2737 {
2738 png_const_charp errmsg = NULL;
2739 png_bytep buffer;
2740 png_uint_32 prefix_length;
2741
2742 png_debug(1, "in png_handle_iTXt");
2743
2744 #ifdef PNG_USER_LIMITS_SUPPORTED
2745 if (png_ptr->user_chunk_cache_max != 0)
2746 {
2747 if (png_ptr->user_chunk_cache_max == 1)
2748 {
2749 png_crc_finish(png_ptr, length);
2750 return;
2751 }
2752
2753 if (--png_ptr->user_chunk_cache_max == 1)
2754 {
2755 png_crc_finish(png_ptr, length);
2756 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2757 return;
2758 }
2759 }
2760 #endif
2761
2762 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2763 png_chunk_error(png_ptr, "missing IHDR");
2764
2765 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2766 png_ptr->mode |= PNG_AFTER_IDAT;
2767
2768 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2769
2770 if (buffer == NULL)
2771 {
2772 png_crc_finish(png_ptr, length);
2773 png_chunk_benign_error(png_ptr, "out of memory");
2774 return;
2775 }
2776
2777 png_crc_read(png_ptr, buffer, length);
2778
2779 if (png_crc_finish(png_ptr, 0) != 0)
2780 return;
2781
2782 /* First the keyword. */
2783 for (prefix_length=0;
2784 prefix_length < length && buffer[prefix_length] != 0;
2785 ++prefix_length)
2786 /* Empty loop */ ;
2787
2788 /* Perform a basic check on the keyword length here. */
2789 if (prefix_length > 79 || prefix_length < 1)
2790 errmsg = "bad keyword";
2791
2792 /* Expect keyword, compression flag, compression type, language, translated
2793 * keyword (both may be empty but are 0 terminated) then the text, which may
2794 * be empty.
2795 */
2796 else if (prefix_length + 5 > length)
2797 errmsg = "truncated";
2798
2799 else if (buffer[prefix_length+1] == 0 ||
2800 (buffer[prefix_length+1] == 1 &&
2801 buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
2802 {
2803 int compressed = buffer[prefix_length+1] != 0;
2804 png_uint_32 language_offset, translated_keyword_offset;
2805 png_alloc_size_t uncompressed_length = 0;
2806
2807 /* Now the language tag */
2808 prefix_length += 3;
2809 language_offset = prefix_length;
2810
2811 for (; prefix_length < length && buffer[prefix_length] != 0;
2812 ++prefix_length)
2813 /* Empty loop */ ;
2814
2815 /* WARNING: the length may be invalid here, this is checked below. */
2816 translated_keyword_offset = ++prefix_length;
2817
2818 for (; prefix_length < length && buffer[prefix_length] != 0;
2819 ++prefix_length)
2820 /* Empty loop */ ;
2821
2822 /* prefix_length should now be at the trailing '\0' of the translated
2823 * keyword, but it may already be over the end. None of this arithmetic
2824 * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
2825 * systems the available allocation may overflow.
2826 */
2827 ++prefix_length;
2828
2829 if (compressed == 0 && prefix_length <= length)
2830 uncompressed_length = length - prefix_length;
2831
2832 else if (compressed != 0 && prefix_length < length)
2833 {
2834 uncompressed_length = PNG_SIZE_MAX;
2835
2836 /* TODO: at present png_decompress_chunk imposes a single application
2837 * level memory limit, this should be split to different values for
2838 * iCCP and text chunks.
2839 */
2840 if (png_decompress_chunk(png_ptr, length, prefix_length,
2841 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2842 buffer = png_ptr->read_buffer;
2843
2844 else
2845 errmsg = png_ptr->zstream.msg;
2846 }
2847
2848 else
2849 errmsg = "truncated";
2850
2851 if (errmsg == NULL)
2852 {
2853 png_text text;
2854
2855 buffer[uncompressed_length+prefix_length] = 0;
2856
2857 if (compressed == 0)
2858 text.compression = PNG_ITXT_COMPRESSION_NONE;
2859
2860 else
2861 text.compression = PNG_ITXT_COMPRESSION_zTXt;
2862
2863 text.key = (png_charp)buffer;
2864 text.lang = (png_charp)buffer + language_offset;
2865 text.lang_key = (png_charp)buffer + translated_keyword_offset;
2866 text.text = (png_charp)buffer + prefix_length;
2867 text.text_length = 0;
2868 text.itxt_length = uncompressed_length;
2869
2870 if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
2871 errmsg = "insufficient memory";
2872 }
2873 }
2874
2875 else
2876 errmsg = "bad compression info";
2877
2878 if (errmsg != NULL)
2879 png_chunk_benign_error(png_ptr, errmsg);
2880 }
2881 #endif
2882
2883 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2884 /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
2885 static int
2886 png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
2887 {
2888 png_alloc_size_t limit = PNG_SIZE_MAX;
2889
2890 if (png_ptr->unknown_chunk.data != NULL)
2891 {
2892 png_free(png_ptr, png_ptr->unknown_chunk.data);
2893 png_ptr->unknown_chunk.data = NULL;
2894 }
2895
2896 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
2897 if (png_ptr->user_chunk_malloc_max > 0 &&
2898 png_ptr->user_chunk_malloc_max < limit)
2899 limit = png_ptr->user_chunk_malloc_max;
2900
2901 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
2902 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
2903 limit = PNG_USER_CHUNK_MALLOC_MAX;
2904 # endif
2905
2906 if (length <= limit)
2907 {
2908 PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
2909 /* The following is safe because of the PNG_SIZE_MAX init above */
2910 png_ptr->unknown_chunk.size = (size_t)length/*SAFE*/;
2911 /* 'mode' is a flag array, only the bottom four bits matter here */
2912 png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
2913
2914 if (length == 0)
2915 png_ptr->unknown_chunk.data = NULL;
2916
2917 else
2918 {
2919 /* Do a 'warn' here - it is handled below. */
2920 png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
2921 png_malloc_warn(png_ptr, length));
2922 }
2923 }
2924
2925 if (png_ptr->unknown_chunk.data == NULL && length > 0)
2926 {
2927 /* This is benign because we clean up correctly */
2928 png_crc_finish(png_ptr, length);
2929 png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
2930 return 0;
2931 }
2932
2933 else
2934 {
2935 if (length > 0)
2936 png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
2937 png_crc_finish(png_ptr, 0);
2938 return 1;
2939 }
2940 }
2941 #endif /* READ_UNKNOWN_CHUNKS */
2942
2943 /* Handle an unknown, or known but disabled, chunk */
2944 void /* PRIVATE */
2945 png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
2946 png_uint_32 length, int keep)
2947 {
2948 int handled = 0; /* the chunk was handled */
2949
2950 png_debug(1, "in png_handle_unknown");
2951
2952 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2953 /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
2954 * the bug which meant that setting a non-default behavior for a specific
2955 * chunk would be ignored (the default was always used unless a user
2956 * callback was installed).
2957 *
2958 * 'keep' is the value from the png_chunk_unknown_handling, the setting for
2959 * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
2960 * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
2961 * This is just an optimization to avoid multiple calls to the lookup
2962 * function.
2963 */
2964 # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
2965 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2966 keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
2967 # endif
2968 # endif
2969
2970 /* One of the following methods will read the chunk or skip it (at least one
2971 * of these is always defined because this is the only way to switch on
2972 * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
2973 */
2974 # ifdef PNG_READ_USER_CHUNKS_SUPPORTED
2975 /* The user callback takes precedence over the chunk keep value, but the
2976 * keep value is still required to validate a save of a critical chunk.
2977 */
2978 if (png_ptr->read_user_chunk_fn != NULL)
2979 {
2980 if (png_cache_unknown_chunk(png_ptr, length) != 0)
2981 {
2982 /* Callback to user unknown chunk handler */
2983 int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
2984 &png_ptr->unknown_chunk);
2985
2986 /* ret is:
2987 * negative: An error occurred; png_chunk_error will be called.
2988 * zero: The chunk was not handled, the chunk will be discarded
2989 * unless png_set_keep_unknown_chunks has been used to set
2990 * a 'keep' behavior for this particular chunk, in which
2991 * case that will be used. A critical chunk will cause an
2992 * error at this point unless it is to be saved.
2993 * positive: The chunk was handled, libpng will ignore/discard it.
2994 */
2995 if (ret < 0)
2996 png_chunk_error(png_ptr, "error in user chunk");
2997
2998 else if (ret == 0)
2999 {
3000 /* If the keep value is 'default' or 'never' override it, but
3001 * still error out on critical chunks unless the keep value is
3002 * 'always' While this is weird it is the behavior in 1.4.12.
3003 * A possible improvement would be to obey the value set for the
3004 * chunk, but this would be an API change that would probably
3005 * damage some applications.
3006 *
3007 * The png_app_warning below catches the case that matters, where
3008 * the application has not set specific save or ignore for this
3009 * chunk or global save or ignore.
3010 */
3011 if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
3012 {
3013 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
3014 if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
3015 {
3016 png_chunk_warning(png_ptr, "Saving unknown chunk:");
3017 png_app_warning(png_ptr,
3018 "forcing save of an unhandled chunk;"
3019 " please call png_set_keep_unknown_chunks");
3020 /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
3021 }
3022 # endif
3023 keep = PNG_HANDLE_CHUNK_IF_SAFE;
3024 }
3025 }
3026
3027 else /* chunk was handled */
3028 {
3029 handled = 1;
3030 /* Critical chunks can be safely discarded at this point. */
3031 keep = PNG_HANDLE_CHUNK_NEVER;
3032 }
3033 }
3034
3035 else
3036 keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
3037 }
3038
3039 else
3040 /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
3041 # endif /* READ_USER_CHUNKS */
3042
3043 # ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
3044 {
3045 /* keep is currently just the per-chunk setting, if there was no
3046 * setting change it to the global default now (not that this may
3047 * still be AS_DEFAULT) then obtain the cache of the chunk if required,
3048 * if not simply skip the chunk.
3049 */
3050 if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
3051 keep = png_ptr->unknown_default;
3052
3053 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
3054 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
3055 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
3056 {
3057 if (png_cache_unknown_chunk(png_ptr, length) == 0)
3058 keep = PNG_HANDLE_CHUNK_NEVER;
3059 }
3060
3061 else
3062 png_crc_finish(png_ptr, length);
3063 }
3064 # else
3065 # ifndef PNG_READ_USER_CHUNKS_SUPPORTED
3066 # error no method to support READ_UNKNOWN_CHUNKS
3067 # endif
3068
3069 {
3070 /* If here there is no read callback pointer set and no support is
3071 * compiled in to just save the unknown chunks, so simply skip this
3072 * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then
3073 * the app has erroneously asked for unknown chunk saving when there
3074 * is no support.
3075 */
3076 if (keep > PNG_HANDLE_CHUNK_NEVER)
3077 png_app_error(png_ptr, "no unknown chunk support available");
3078
3079 png_crc_finish(png_ptr, length);
3080 }
3081 # endif
3082
3083 # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
3084 /* Now store the chunk in the chunk list if appropriate, and if the limits
3085 * permit it.
3086 */
3087 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
3088 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
3089 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
3090 {
3091 # ifdef PNG_USER_LIMITS_SUPPORTED
3092 switch (png_ptr->user_chunk_cache_max)
3093 {
3094 case 2:
3095 png_ptr->user_chunk_cache_max = 1;
3096 png_chunk_benign_error(png_ptr, "no space in chunk cache");
3097 /* FALLTHROUGH */
3098 case 1:
3099 /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
3100 * chunk being skipped, now there will be a hard error below.
3101 */
3102 break;
3103
3104 default: /* not at limit */
3105 --(png_ptr->user_chunk_cache_max);
3106 /* FALLTHROUGH */
3107 case 0: /* no limit */
3108 # endif /* USER_LIMITS */
3109 /* Here when the limit isn't reached or when limits are compiled
3110 * out; store the chunk.
3111 */
3112 png_set_unknown_chunks(png_ptr, info_ptr,
3113 &png_ptr->unknown_chunk, 1);
3114 handled = 1;
3115 # ifdef PNG_USER_LIMITS_SUPPORTED
3116 break;
3117 }
3118 # endif
3119 }
3120 # else /* no store support: the chunk must be handled by the user callback */
3121 PNG_UNUSED(info_ptr)
3122 # endif
3123
3124 /* Regardless of the error handling below the cached data (if any) can be
3125 * freed now. Notice that the data is not freed if there is a png_error, but
3126 * it will be freed by destroy_read_struct.
3127 */
3128 if (png_ptr->unknown_chunk.data != NULL)
3129 png_free(png_ptr, png_ptr->unknown_chunk.data);
3130 png_ptr->unknown_chunk.data = NULL;
3131
3132 #else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
3133 /* There is no support to read an unknown chunk, so just skip it. */
3134 png_crc_finish(png_ptr, length);
3135 PNG_UNUSED(info_ptr)
3136 PNG_UNUSED(keep)
3137 #endif /* !READ_UNKNOWN_CHUNKS */
3138
3139 /* Check for unhandled critical chunks */
3140 if (handled == 0 && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
3141 png_chunk_error(png_ptr, "unhandled critical chunk");
3142 }
3143
3144 /* This function is called to verify that a chunk name is valid.
3145 * This function can't have the "critical chunk check" incorporated
3146 * into it, since in the future we will need to be able to call user
3147 * functions to handle unknown critical chunks after we check that
3148 * the chunk name itself is valid.
3149 */
3150
3151 /* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
3152 *
3153 * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
3154 */
3155
3156 void /* PRIVATE */
3157 png_check_chunk_name(png_const_structrp png_ptr, png_uint_32 chunk_name)
3158 {
3159 int i;
3160 png_uint_32 cn=chunk_name;
3161
3162 png_debug(1, "in png_check_chunk_name");
3163
3164 for (i=1; i<=4; ++i)
3165 {
3166 int c = cn & 0xff;
3167
3168 if (c < 65 || c > 122 || (c > 90 && c < 97))
3169 png_chunk_error(png_ptr, "invalid chunk type");
3170
3171 cn >>= 8;
3172 }
3173 }
3174
3175 void /* PRIVATE */
3176 png_check_chunk_length(png_const_structrp png_ptr, png_uint_32 length)
3177 {
3178 png_alloc_size_t limit = PNG_UINT_31_MAX;
3179
3180 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
3181 if (png_ptr->user_chunk_malloc_max > 0 &&
3182 png_ptr->user_chunk_malloc_max < limit)
3183 limit = png_ptr->user_chunk_malloc_max;
3184 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
3185 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
3186 limit = PNG_USER_CHUNK_MALLOC_MAX;
3187 # endif
3188 if (png_ptr->chunk_name == png_IDAT)
3189 {
3190 png_alloc_size_t idat_limit = PNG_UINT_31_MAX;
3191 size_t row_factor =
3192 (size_t)png_ptr->width
3193 * (size_t)png_ptr->channels
3194 * (png_ptr->bit_depth > 8? 2: 1)
3195 + 1
3196 + (png_ptr->interlaced? 6: 0);
3197 if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
3198 idat_limit = PNG_UINT_31_MAX;
3199 else
3200 idat_limit = png_ptr->height * row_factor;
3201 row_factor = row_factor > 32566? 32566 : row_factor;
3202 idat_limit += 6 + 5*(idat_limit/row_factor+1); /* zlib+deflate overhead */
3203 idat_limit=idat_limit < PNG_UINT_31_MAX? idat_limit : PNG_UINT_31_MAX;
3204 limit = limit < idat_limit? idat_limit : limit;
3205 }
3206
3207 if (length > limit)
3208 {
3209 png_debug2(0," length = %lu, limit = %lu",
3210 (unsigned long)length,(unsigned long)limit);
3211 png_chunk_error(png_ptr, "chunk data is too large");
3212 }
3213 }
3214
3215 /* Combines the row recently read in with the existing pixels in the row. This
3216 * routine takes care of alpha and transparency if requested. This routine also
3217 * handles the two methods of progressive display of interlaced images,
3218 * depending on the 'display' value; if 'display' is true then the whole row
3219 * (dp) is filled from the start by replicating the available pixels. If
3220 * 'display' is false only those pixels present in the pass are filled in.
3221 */
3222 void /* PRIVATE */
3223 png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
3224 {
3225 unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
3226 png_const_bytep sp = png_ptr->row_buf + 1;
3227 png_alloc_size_t row_width = png_ptr->width;
3228 unsigned int pass = png_ptr->pass;
3229 png_bytep end_ptr = 0;
3230 png_byte end_byte = 0;
3231 unsigned int end_mask;
3232
3233 png_debug(1, "in png_combine_row");
3234
3235 /* Added in 1.5.6: it should not be possible to enter this routine until at
3236 * least one row has been read from the PNG data and transformed.
3237 */
3238 if (pixel_depth == 0)
3239 png_error(png_ptr, "internal row logic error");
3240
3241 /* Added in 1.5.4: the pixel depth should match the information returned by
3242 * any call to png_read_update_info at this point. Do not continue if we got
3243 * this wrong.
3244 */
3245 if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
3246 PNG_ROWBYTES(pixel_depth, row_width))
3247 png_error(png_ptr, "internal row size calculation error");
3248
3249 /* Don't expect this to ever happen: */
3250 if (row_width == 0)
3251 png_error(png_ptr, "internal row width error");
3252
3253 /* Preserve the last byte in cases where only part of it will be overwritten,
3254 * the multiply below may overflow, we don't care because ANSI-C guarantees
3255 * we get the low bits.
3256 */
3257 end_mask = (pixel_depth * row_width) & 7;
3258 if (end_mask != 0)
3259 {
3260 /* end_ptr == NULL is a flag to say do nothing */
3261 end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
3262 end_byte = *end_ptr;
3263 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3264 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
3265 /* little-endian byte */
3266 end_mask = (unsigned int)(0xff << end_mask);
3267
3268 else /* big-endian byte */
3269 # endif
3270 end_mask = 0xff >> end_mask;
3271 /* end_mask is now the bits to *keep* from the destination row */
3272 }
3273
3274 /* For non-interlaced images this reduces to a memcpy(). A memcpy()
3275 * will also happen if interlacing isn't supported or if the application
3276 * does not call png_set_interlace_handling(). In the latter cases the
3277 * caller just gets a sequence of the unexpanded rows from each interlace
3278 * pass.
3279 */
3280 #ifdef PNG_READ_INTERLACING_SUPPORTED
3281 if (png_ptr->interlaced != 0 &&
3282 (png_ptr->transformations & PNG_INTERLACE) != 0 &&
3283 pass < 6 && (display == 0 ||
3284 /* The following copies everything for 'display' on passes 0, 2 and 4. */
3285 (display == 1 && (pass & 1) != 0)))
3286 {
3287 /* Narrow images may have no bits in a pass; the caller should handle
3288 * this, but this test is cheap:
3289 */
3290 if (row_width <= PNG_PASS_START_COL(pass))
3291 return;
3292
3293 if (pixel_depth < 8)
3294 {
3295 /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
3296 * into 32 bits, then a single loop over the bytes using the four byte
3297 * values in the 32-bit mask can be used. For the 'display' option the
3298 * expanded mask may also not require any masking within a byte. To
3299 * make this work the PACKSWAP option must be taken into account - it
3300 * simply requires the pixels to be reversed in each byte.
3301 *
3302 * The 'regular' case requires a mask for each of the first 6 passes,
3303 * the 'display' case does a copy for the even passes in the range
3304 * 0..6. This has already been handled in the test above.
3305 *
3306 * The masks are arranged as four bytes with the first byte to use in
3307 * the lowest bits (little-endian) regardless of the order (PACKSWAP or
3308 * not) of the pixels in each byte.
3309 *
3310 * NOTE: the whole of this logic depends on the caller of this function
3311 * only calling it on rows appropriate to the pass. This function only
3312 * understands the 'x' logic; the 'y' logic is handled by the caller.
3313 *
3314 * The following defines allow generation of compile time constant bit
3315 * masks for each pixel depth and each possibility of swapped or not
3316 * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index,
3317 * is in the range 0..7; and the result is 1 if the pixel is to be
3318 * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B'
3319 * for the block method.
3320 *
3321 * With some compilers a compile time expression of the general form:
3322 *
3323 * (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
3324 *
3325 * Produces warnings with values of 'shift' in the range 33 to 63
3326 * because the right hand side of the ?: expression is evaluated by
3327 * the compiler even though it isn't used. Microsoft Visual C (various
3328 * versions) and the Intel C compiler are known to do this. To avoid
3329 * this the following macros are used in 1.5.6. This is a temporary
3330 * solution to avoid destabilizing the code during the release process.
3331 */
3332 # if PNG_USE_COMPILE_TIME_MASKS
3333 # define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
3334 # define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
3335 # else
3336 # define PNG_LSR(x,s) ((x)>>(s))
3337 # define PNG_LSL(x,s) ((x)<<(s))
3338 # endif
3339 # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
3340 PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
3341 # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
3342 PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
3343
3344 /* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is
3345 * little endian - the first pixel is at bit 0 - however the extra
3346 * parameter 's' can be set to cause the mask position to be swapped
3347 * within each byte, to match the PNG format. This is done by XOR of
3348 * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
3349 */
3350 # define PIXEL_MASK(p,x,d,s) \
3351 (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
3352
3353 /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
3354 */
3355 # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3356 # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3357
3358 /* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp
3359 * cases the result needs replicating, for the 4-bpp case the above
3360 * generates a full 32 bits.
3361 */
3362 # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
3363
3364 # define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
3365 S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
3366 S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
3367
3368 # define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
3369 B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
3370 B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
3371
3372 #if PNG_USE_COMPILE_TIME_MASKS
3373 /* Utility macros to construct all the masks for a depth/swap
3374 * combination. The 's' parameter says whether the format is PNG
3375 * (big endian bytes) or not. Only the three odd-numbered passes are
3376 * required for the display/block algorithm.
3377 */
3378 # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
3379 S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
3380
3381 # define B_MASKS(d,s) { B_MASK(1,d,s), B_MASK(3,d,s), B_MASK(5,d,s) }
3382
3383 # define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
3384
3385 /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
3386 * then pass:
3387 */
3388 static const png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
3389 {
3390 /* Little-endian byte masks for PACKSWAP */
3391 { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
3392 /* Normal (big-endian byte) masks - PNG format */
3393 { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
3394 };
3395
3396 /* display_mask has only three entries for the odd passes, so index by
3397 * pass>>1.
3398 */
3399 static const png_uint_32 display_mask[2][3][3] =
3400 {
3401 /* Little-endian byte masks for PACKSWAP */
3402 { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
3403 /* Normal (big-endian byte) masks - PNG format */
3404 { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
3405 };
3406
3407 # define MASK(pass,depth,display,png)\
3408 ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
3409 row_mask[png][DEPTH_INDEX(depth)][pass])
3410
3411 #else /* !PNG_USE_COMPILE_TIME_MASKS */
3412 /* This is the runtime alternative: it seems unlikely that this will
3413 * ever be either smaller or faster than the compile time approach.
3414 */
3415 # define MASK(pass,depth,display,png)\
3416 ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
3417 #endif /* !USE_COMPILE_TIME_MASKS */
3418
3419 /* Use the appropriate mask to copy the required bits. In some cases
3420 * the byte mask will be 0 or 0xff; optimize these cases. row_width is
3421 * the number of pixels, but the code copies bytes, so it is necessary
3422 * to special case the end.
3423 */
3424 png_uint_32 pixels_per_byte = 8 / pixel_depth;
3425 png_uint_32 mask;
3426
3427 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3428 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
3429 mask = MASK(pass, pixel_depth, display, 0);
3430
3431 else
3432 # endif
3433 mask = MASK(pass, pixel_depth, display, 1);
3434
3435 for (;;)
3436 {
3437 png_uint_32 m;
3438
3439 /* It doesn't matter in the following if png_uint_32 has more than
3440 * 32 bits because the high bits always match those in m<<24; it is,
3441 * however, essential to use OR here, not +, because of this.
3442 */
3443 m = mask;
3444 mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
3445 m &= 0xff;
3446
3447 if (m != 0) /* something to copy */
3448 {
3449 if (m != 0xff)
3450 *dp = (png_byte)((*dp & ~m) | (*sp & m));
3451 else
3452 *dp = *sp;
3453 }
3454
3455 /* NOTE: this may overwrite the last byte with garbage if the image
3456 * is not an exact number of bytes wide; libpng has always done
3457 * this.
3458 */
3459 if (row_width <= pixels_per_byte)
3460 break; /* May need to restore part of the last byte */
3461
3462 row_width -= pixels_per_byte;
3463 ++dp;
3464 ++sp;
3465 }
3466 }
3467
3468 else /* pixel_depth >= 8 */
3469 {
3470 unsigned int bytes_to_copy, bytes_to_jump;
3471
3472 /* Validate the depth - it must be a multiple of 8 */
3473 if (pixel_depth & 7)
3474 png_error(png_ptr, "invalid user transform pixel depth");
3475
3476 pixel_depth >>= 3; /* now in bytes */
3477 row_width *= pixel_depth;
3478
3479 /* Regardless of pass number the Adam 7 interlace always results in a
3480 * fixed number of pixels to copy then to skip. There may be a
3481 * different number of pixels to skip at the start though.
3482 */
3483 {
3484 unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
3485
3486 row_width -= offset;
3487 dp += offset;
3488 sp += offset;
3489 }
3490
3491 /* Work out the bytes to copy. */
3492 if (display != 0)
3493 {
3494 /* When doing the 'block' algorithm the pixel in the pass gets
3495 * replicated to adjacent pixels. This is why the even (0,2,4,6)
3496 * passes are skipped above - the entire expanded row is copied.
3497 */
3498 bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
3499
3500 /* But don't allow this number to exceed the actual row width. */
3501 if (bytes_to_copy > row_width)
3502 bytes_to_copy = (unsigned int)/*SAFE*/row_width;
3503 }
3504
3505 else /* normal row; Adam7 only ever gives us one pixel to copy. */
3506 bytes_to_copy = pixel_depth;
3507
3508 /* In Adam7 there is a constant offset between where the pixels go. */
3509 bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
3510
3511 /* And simply copy these bytes. Some optimization is possible here,
3512 * depending on the value of 'bytes_to_copy'. Special case the low
3513 * byte counts, which we know to be frequent.
3514 *
3515 * Notice that these cases all 'return' rather than 'break' - this
3516 * avoids an unnecessary test on whether to restore the last byte
3517 * below.
3518 */
3519 switch (bytes_to_copy)
3520 {
3521 case 1:
3522 for (;;)
3523 {
3524 *dp = *sp;
3525
3526 if (row_width <= bytes_to_jump)
3527 return;
3528
3529 dp += bytes_to_jump;
3530 sp += bytes_to_jump;
3531 row_width -= bytes_to_jump;
3532 }
3533
3534 case 2:
3535 /* There is a possibility of a partial copy at the end here; this
3536 * slows the code down somewhat.
3537 */
3538 do
3539 {
3540 dp[0] = sp[0]; dp[1] = sp[1];
3541
3542 if (row_width <= bytes_to_jump)
3543 return;
3544
3545 sp += bytes_to_jump;
3546 dp += bytes_to_jump;
3547 row_width -= bytes_to_jump;
3548 }
3549 while (row_width > 1);
3550
3551 /* And there can only be one byte left at this point: */
3552 *dp = *sp;
3553 return;
3554
3555 case 3:
3556 /* This can only be the RGB case, so each copy is exactly one
3557 * pixel and it is not necessary to check for a partial copy.
3558 */
3559 for (;;)
3560 {
3561 dp[0] = sp[0]; dp[1] = sp[1]; dp[2] = sp[2];
3562
3563 if (row_width <= bytes_to_jump)
3564 return;
3565
3566 sp += bytes_to_jump;
3567 dp += bytes_to_jump;
3568 row_width -= bytes_to_jump;
3569 }
3570
3571 default:
3572 #if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
3573 /* Check for double byte alignment and, if possible, use a
3574 * 16-bit copy. Don't attempt this for narrow images - ones that
3575 * are less than an interlace panel wide. Don't attempt it for
3576 * wide bytes_to_copy either - use the memcpy there.
3577 */
3578 if (bytes_to_copy < 16 /*else use memcpy*/ &&
3579 png_isaligned(dp, png_uint_16) &&
3580 png_isaligned(sp, png_uint_16) &&
3581 bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
3582 bytes_to_jump % (sizeof (png_uint_16)) == 0)
3583 {
3584 /* Everything is aligned for png_uint_16 copies, but try for
3585 * png_uint_32 first.
3586 */
3587 if (png_isaligned(dp, png_uint_32) &&
3588 png_isaligned(sp, png_uint_32) &&
3589 bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
3590 bytes_to_jump % (sizeof (png_uint_32)) == 0)
3591 {
3592 png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
3593 png_const_uint_32p sp32 = png_aligncastconst(
3594 png_const_uint_32p, sp);
3595 size_t skip = (bytes_to_jump-bytes_to_copy) /
3596 (sizeof (png_uint_32));
3597
3598 do
3599 {
3600 size_t c = bytes_to_copy;
3601 do
3602 {
3603 *dp32++ = *sp32++;
3604 c -= (sizeof (png_uint_32));
3605 }
3606 while (c > 0);
3607
3608 if (row_width <= bytes_to_jump)
3609 return;
3610
3611 dp32 += skip;
3612 sp32 += skip;
3613 row_width -= bytes_to_jump;
3614 }
3615 while (bytes_to_copy <= row_width);
3616
3617 /* Get to here when the row_width truncates the final copy.
3618 * There will be 1-3 bytes left to copy, so don't try the
3619 * 16-bit loop below.
3620 */
3621 dp = (png_bytep)dp32;
3622 sp = (png_const_bytep)sp32;
3623 do
3624 *dp++ = *sp++;
3625 while (--row_width > 0);
3626 return;
3627 }
3628
3629 /* Else do it in 16-bit quantities, but only if the size is
3630 * not too large.
3631 */
3632 else
3633 {
3634 png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
3635 png_const_uint_16p sp16 = png_aligncastconst(
3636 png_const_uint_16p, sp);
3637 size_t skip = (bytes_to_jump-bytes_to_copy) /
3638 (sizeof (png_uint_16));
3639
3640 do
3641 {
3642 size_t c = bytes_to_copy;
3643 do
3644 {
3645 *dp16++ = *sp16++;
3646 c -= (sizeof (png_uint_16));
3647 }
3648 while (c > 0);
3649
3650 if (row_width <= bytes_to_jump)
3651 return;
3652
3653 dp16 += skip;
3654 sp16 += skip;
3655 row_width -= bytes_to_jump;
3656 }
3657 while (bytes_to_copy <= row_width);
3658
3659 /* End of row - 1 byte left, bytes_to_copy > row_width: */
3660 dp = (png_bytep)dp16;
3661 sp = (png_const_bytep)sp16;
3662 do
3663 *dp++ = *sp++;
3664 while (--row_width > 0);
3665 return;
3666 }
3667 }
3668 #endif /* ALIGN_TYPE code */
3669
3670 /* The true default - use a memcpy: */
3671 for (;;)
3672 {
3673 memcpy(dp, sp, bytes_to_copy);
3674
3675 if (row_width <= bytes_to_jump)
3676 return;
3677
3678 sp += bytes_to_jump;
3679 dp += bytes_to_jump;
3680 row_width -= bytes_to_jump;
3681 if (bytes_to_copy > row_width)
3682 bytes_to_copy = (unsigned int)/*SAFE*/row_width;
3683 }
3684 }
3685
3686 /* NOT REACHED*/
3687 } /* pixel_depth >= 8 */
3688
3689 /* Here if pixel_depth < 8 to check 'end_ptr' below. */
3690 }
3691 else
3692 #endif /* READ_INTERLACING */
3693
3694 /* If here then the switch above wasn't used so just memcpy the whole row
3695 * from the temporary row buffer (notice that this overwrites the end of the
3696 * destination row if it is a partial byte.)
3697 */
3698 memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
3699
3700 /* Restore the overwritten bits from the last byte if necessary. */
3701 if (end_ptr != NULL)
3702 *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
3703 }
3704
3705 #ifdef PNG_READ_INTERLACING_SUPPORTED
3706 void /* PRIVATE */
3707 png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
3708 png_uint_32 transformations /* Because these may affect the byte layout */)
3709 {
3710 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
3711 /* Offset to next interlace block */
3712 static const unsigned int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
3713
3714 png_debug(1, "in png_do_read_interlace");
3715 if (row != NULL && row_info != NULL)
3716 {
3717 png_uint_32 final_width;
3718
3719 final_width = row_info->width * png_pass_inc[pass];
3720
3721 switch (row_info->pixel_depth)
3722 {
3723 case 1:
3724 {
3725 png_bytep sp = row + (size_t)((row_info->width - 1) >> 3);
3726 png_bytep dp = row + (size_t)((final_width - 1) >> 3);
3727 unsigned int sshift, dshift;
3728 unsigned int s_start, s_end;
3729 int s_inc;
3730 int jstop = (int)png_pass_inc[pass];
3731 png_byte v;
3732 png_uint_32 i;
3733 int j;
3734
3735 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3736 if ((transformations & PNG_PACKSWAP) != 0)
3737 {
3738 sshift = ((row_info->width + 7) & 0x07);
3739 dshift = ((final_width + 7) & 0x07);
3740 s_start = 7;
3741 s_end = 0;
3742 s_inc = -1;
3743 }
3744
3745 else
3746 #endif
3747 {
3748 sshift = 7 - ((row_info->width + 7) & 0x07);
3749 dshift = 7 - ((final_width + 7) & 0x07);
3750 s_start = 0;
3751 s_end = 7;
3752 s_inc = 1;
3753 }
3754
3755 for (i = 0; i < row_info->width; i++)
3756 {
3757 v = (png_byte)((*sp >> sshift) & 0x01);
3758 for (j = 0; j < jstop; j++)
3759 {
3760 unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
3761 tmp |= (unsigned int)(v << dshift);
3762 *dp = (png_byte)(tmp & 0xff);
3763
3764 if (dshift == s_end)
3765 {
3766 dshift = s_start;
3767 dp--;
3768 }
3769
3770 else
3771 dshift = (unsigned int)((int)dshift + s_inc);
3772 }
3773
3774 if (sshift == s_end)
3775 {
3776 sshift = s_start;
3777 sp--;
3778 }
3779
3780 else
3781 sshift = (unsigned int)((int)sshift + s_inc);
3782 }
3783 break;
3784 }
3785
3786 case 2:
3787 {
3788 png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
3789 png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
3790 unsigned int sshift, dshift;
3791 unsigned int s_start, s_end;
3792 int s_inc;
3793 int jstop = (int)png_pass_inc[pass];
3794 png_uint_32 i;
3795
3796 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3797 if ((transformations & PNG_PACKSWAP) != 0)
3798 {
3799 sshift = (((row_info->width + 3) & 0x03) << 1);
3800 dshift = (((final_width + 3) & 0x03) << 1);
3801 s_start = 6;
3802 s_end = 0;
3803 s_inc = -2;
3804 }
3805
3806 else
3807 #endif
3808 {
3809 sshift = ((3 - ((row_info->width + 3) & 0x03)) << 1);
3810 dshift = ((3 - ((final_width + 3) & 0x03)) << 1);
3811 s_start = 0;
3812 s_end = 6;
3813 s_inc = 2;
3814 }
3815
3816 for (i = 0; i < row_info->width; i++)
3817 {
3818 png_byte v;
3819 int j;
3820
3821 v = (png_byte)((*sp >> sshift) & 0x03);
3822 for (j = 0; j < jstop; j++)
3823 {
3824 unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
3825 tmp |= (unsigned int)(v << dshift);
3826 *dp = (png_byte)(tmp & 0xff);
3827
3828 if (dshift == s_end)
3829 {
3830 dshift = s_start;
3831 dp--;
3832 }
3833
3834 else
3835 dshift = (unsigned int)((int)dshift + s_inc);
3836 }
3837
3838 if (sshift == s_end)
3839 {
3840 sshift = s_start;
3841 sp--;
3842 }
3843
3844 else
3845 sshift = (unsigned int)((int)sshift + s_inc);
3846 }
3847 break;
3848 }
3849
3850 case 4:
3851 {
3852 png_bytep sp = row + (size_t)((row_info->width - 1) >> 1);
3853 png_bytep dp = row + (size_t)((final_width - 1) >> 1);
3854 unsigned int sshift, dshift;
3855 unsigned int s_start, s_end;
3856 int s_inc;
3857 png_uint_32 i;
3858 int jstop = (int)png_pass_inc[pass];
3859
3860 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3861 if ((transformations & PNG_PACKSWAP) != 0)
3862 {
3863 sshift = (((row_info->width + 1) & 0x01) << 2);
3864 dshift = (((final_width + 1) & 0x01) << 2);
3865 s_start = 4;
3866 s_end = 0;
3867 s_inc = -4;
3868 }
3869
3870 else
3871 #endif
3872 {
3873 sshift = ((1 - ((row_info->width + 1) & 0x01)) << 2);
3874 dshift = ((1 - ((final_width + 1) & 0x01)) << 2);
3875 s_start = 0;
3876 s_end = 4;
3877 s_inc = 4;
3878 }
3879
3880 for (i = 0; i < row_info->width; i++)
3881 {
3882 png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
3883 int j;
3884
3885 for (j = 0; j < jstop; j++)
3886 {
3887 unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
3888 tmp |= (unsigned int)(v << dshift);
3889 *dp = (png_byte)(tmp & 0xff);
3890
3891 if (dshift == s_end)
3892 {
3893 dshift = s_start;
3894 dp--;
3895 }
3896
3897 else
3898 dshift = (unsigned int)((int)dshift + s_inc);
3899 }
3900
3901 if (sshift == s_end)
3902 {
3903 sshift = s_start;
3904 sp--;
3905 }
3906
3907 else
3908 sshift = (unsigned int)((int)sshift + s_inc);
3909 }
3910 break;
3911 }
3912
3913 default:
3914 {
3915 size_t pixel_bytes = (row_info->pixel_depth >> 3);
3916
3917 png_bytep sp = row + (size_t)(row_info->width - 1)
3918 * pixel_bytes;
3919
3920 png_bytep dp = row + (size_t)(final_width - 1) * pixel_bytes;
3921
3922 int jstop = (int)png_pass_inc[pass];
3923 png_uint_32 i;
3924
3925 for (i = 0; i < row_info->width; i++)
3926 {
3927 png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
3928 int j;
3929
3930 memcpy(v, sp, pixel_bytes);
3931
3932 for (j = 0; j < jstop; j++)
3933 {
3934 memcpy(dp, v, pixel_bytes);
3935 dp -= pixel_bytes;
3936 }
3937
3938 sp -= pixel_bytes;
3939 }
3940 break;
3941 }
3942 }
3943
3944 row_info->width = final_width;
3945 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
3946 }
3947 #ifndef PNG_READ_PACKSWAP_SUPPORTED
3948 PNG_UNUSED(transformations) /* Silence compiler warning */
3949 #endif
3950 }
3951 #endif /* READ_INTERLACING */
3952
3953 static void
3954 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
3955 png_const_bytep prev_row)
3956 {
3957 size_t i;
3958 size_t istop = row_info->rowbytes;
3959 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3960 png_bytep rp = row + bpp;
3961
3962 PNG_UNUSED(prev_row)
3963
3964 for (i = bpp; i < istop; i++)
3965 {
3966 *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
3967 rp++;
3968 }
3969 }
3970
3971 static void
3972 png_read_filter_row_up(png_row_infop row_info, png_bytep row,
3973 png_const_bytep prev_row)
3974 {
3975 size_t i;
3976 size_t istop = row_info->rowbytes;
3977 png_bytep rp = row;
3978 png_const_bytep pp = prev_row;
3979
3980 for (i = 0; i < istop; i++)
3981 {
3982 *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
3983 rp++;
3984 }
3985 }
3986
3987 static void
3988 png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
3989 png_const_bytep prev_row)
3990 {
3991 size_t i;
3992 png_bytep rp = row;
3993 png_const_bytep pp = prev_row;
3994 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3995 size_t istop = row_info->rowbytes - bpp;
3996
3997 for (i = 0; i < bpp; i++)
3998 {
3999 *rp = (png_byte)(((int)(*rp) +
4000 ((int)(*pp++) / 2 )) & 0xff);
4001
4002 rp++;
4003 }
4004
4005 for (i = 0; i < istop; i++)
4006 {
4007 *rp = (png_byte)(((int)(*rp) +
4008 (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
4009
4010 rp++;
4011 }
4012 }
4013
4014 static void
4015 png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
4016 png_const_bytep prev_row)
4017 {
4018 png_bytep rp_end = row + row_info->rowbytes;
4019 int a, c;
4020
4021 /* First pixel/byte */
4022 c = *prev_row++;
4023 a = *row + c;
4024 *row++ = (png_byte)a;
4025
4026 /* Remainder */
4027 while (row < rp_end)
4028 {
4029 int b, pa, pb, pc, p;
4030
4031 a &= 0xff; /* From previous iteration or start */
4032 b = *prev_row++;
4033
4034 p = b - c;
4035 pc = a - c;
4036
4037 #ifdef PNG_USE_ABS
4038 pa = abs(p);
4039 pb = abs(pc);
4040 pc = abs(p + pc);
4041 #else
4042 pa = p < 0 ? -p : p;
4043 pb = pc < 0 ? -pc : pc;
4044 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
4045 #endif
4046
4047 /* Find the best predictor, the least of pa, pb, pc favoring the earlier
4048 * ones in the case of a tie.
4049 */
4050 if (pb < pa)
4051 {
4052 pa = pb; a = b;
4053 }
4054 if (pc < pa) a = c;
4055
4056 /* Calculate the current pixel in a, and move the previous row pixel to c
4057 * for the next time round the loop
4058 */
4059 c = b;
4060 a += *row;
4061 *row++ = (png_byte)a;
4062 }
4063 }
4064
4065 static void
4066 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
4067 png_const_bytep prev_row)
4068 {
4069 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
4070 png_bytep rp_end = row + bpp;
4071
4072 /* Process the first pixel in the row completely (this is the same as 'up'
4073 * because there is only one candidate predictor for the first row).
4074 */
4075 while (row < rp_end)
4076 {
4077 int a = *row + *prev_row++;
4078 *row++ = (png_byte)a;
4079 }
4080
4081 /* Remainder */
4082 rp_end = rp_end + (row_info->rowbytes - bpp);
4083
4084 while (row < rp_end)
4085 {
4086 int a, b, c, pa, pb, pc, p;
4087
4088 c = *(prev_row - bpp);
4089 a = *(row - bpp);
4090 b = *prev_row++;
4091
4092 p = b - c;
4093 pc = a - c;
4094
4095 #ifdef PNG_USE_ABS
4096 pa = abs(p);
4097 pb = abs(pc);
4098 pc = abs(p + pc);
4099 #else
4100 pa = p < 0 ? -p : p;
4101 pb = pc < 0 ? -pc : pc;
4102 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
4103 #endif
4104
4105 if (pb < pa)
4106 {
4107 pa = pb; a = b;
4108 }
4109 if (pc < pa) a = c;
4110
4111 a += *row;
4112 *row++ = (png_byte)a;
4113 }
4114 }
4115
4116 static void
4117 png_init_filter_functions(png_structrp pp)
4118 /* This function is called once for every PNG image (except for PNG images
4119 * that only use PNG_FILTER_VALUE_NONE for all rows) to set the
4120 * implementations required to reverse the filtering of PNG rows. Reversing
4121 * the filter is the first transformation performed on the row data. It is
4122 * performed in place, therefore an implementation can be selected based on
4123 * the image pixel format. If the implementation depends on image width then
4124 * take care to ensure that it works correctly if the image is interlaced -
4125 * interlacing causes the actual row width to vary.
4126 */
4127 {
4128 unsigned int bpp = (pp->pixel_depth + 7) >> 3;
4129
4130 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
4131 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
4132 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
4133 if (bpp == 1)
4134 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
4135 png_read_filter_row_paeth_1byte_pixel;
4136 else
4137 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
4138 png_read_filter_row_paeth_multibyte_pixel;
4139
4140 #ifdef PNG_FILTER_OPTIMIZATIONS
4141 /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
4142 * call to install hardware optimizations for the above functions; simply
4143 * replace whatever elements of the pp->read_filter[] array with a hardware
4144 * specific (or, for that matter, generic) optimization.
4145 *
4146 * To see an example of this examine what configure.ac does when
4147 * --enable-arm-neon is specified on the command line.
4148 */
4149 PNG_FILTER_OPTIMIZATIONS(pp, bpp);
4150 #endif
4151 }
4152
4153 void /* PRIVATE */
4154 png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
4155 png_const_bytep prev_row, int filter)
4156 {
4157 /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
4158 * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
4159 * implementations. See png_init_filter_functions above.
4160 */
4161 if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
4162 {
4163 if (pp->read_filter[0] == NULL)
4164 png_init_filter_functions(pp);
4165
4166 pp->read_filter[filter-1](row_info, row, prev_row);
4167 }
4168 }
4169
4170 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
4171 void /* PRIVATE */
4172 png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
4173 png_alloc_size_t avail_out)
4174 {
4175 /* Loop reading IDATs and decompressing the result into output[avail_out] */
4176 png_ptr->zstream.next_out = output;
4177 png_ptr->zstream.avail_out = 0; /* safety: set below */
4178
4179 if (output == NULL)
4180 avail_out = 0;
4181
4182 do
4183 {
4184 int ret;
4185 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
4186
4187 if (png_ptr->zstream.avail_in == 0)
4188 {
4189 uInt avail_in;
4190 png_bytep buffer;
4191
4192 while (png_ptr->idat_size == 0)
4193 {
4194 png_crc_finish(png_ptr, 0);
4195
4196 png_ptr->idat_size = png_read_chunk_header(png_ptr);
4197 /* This is an error even in the 'check' case because the code just
4198 * consumed a non-IDAT header.
4199 */
4200 if (png_ptr->chunk_name != png_IDAT)
4201 png_error(png_ptr, "Not enough image data");
4202 }
4203
4204 avail_in = png_ptr->IDAT_read_size;
4205
4206 if (avail_in > png_ptr->idat_size)
4207 avail_in = (uInt)png_ptr->idat_size;
4208
4209 /* A PNG with a gradually increasing IDAT size will defeat this attempt
4210 * to minimize memory usage by causing lots of re-allocs, but
4211 * realistically doing IDAT_read_size re-allocs is not likely to be a
4212 * big problem.
4213 */
4214 buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
4215
4216 png_crc_read(png_ptr, buffer, avail_in);
4217 png_ptr->idat_size -= avail_in;
4218
4219 png_ptr->zstream.next_in = buffer;
4220 png_ptr->zstream.avail_in = avail_in;
4221 }
4222
4223 /* And set up the output side. */
4224 if (output != NULL) /* standard read */
4225 {
4226 uInt out = ZLIB_IO_MAX;
4227
4228 if (out > avail_out)
4229 out = (uInt)avail_out;
4230
4231 avail_out -= out;
4232 png_ptr->zstream.avail_out = out;
4233 }
4234
4235 else /* after last row, checking for end */
4236 {
4237 png_ptr->zstream.next_out = tmpbuf;
4238 png_ptr->zstream.avail_out = (sizeof tmpbuf);
4239 }
4240
4241 /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
4242 * process. If the LZ stream is truncated the sequential reader will
4243 * terminally damage the stream, above, by reading the chunk header of the
4244 * following chunk (it then exits with png_error).
4245 *
4246 * TODO: deal more elegantly with truncated IDAT lists.
4247 */
4248 ret = PNG_INFLATE(png_ptr, Z_NO_FLUSH);
4249
4250 /* Take the unconsumed output back. */
4251 if (output != NULL)
4252 avail_out += png_ptr->zstream.avail_out;
4253
4254 else /* avail_out counts the extra bytes */
4255 avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
4256
4257 png_ptr->zstream.avail_out = 0;
4258
4259 if (ret == Z_STREAM_END)
4260 {
4261 /* Do this for safety; we won't read any more into this row. */
4262 png_ptr->zstream.next_out = NULL;
4263
4264 png_ptr->mode |= PNG_AFTER_IDAT;
4265 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4266
4267 if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
4268 png_chunk_benign_error(png_ptr, "Extra compressed data");
4269 break;
4270 }
4271
4272 if (ret != Z_OK)
4273 {
4274 png_zstream_error(png_ptr, ret);
4275
4276 if (output != NULL)
4277 png_chunk_error(png_ptr, png_ptr->zstream.msg);
4278
4279 else /* checking */
4280 {
4281 png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
4282 return;
4283 }
4284 }
4285 } while (avail_out > 0);
4286
4287 if (avail_out > 0)
4288 {
4289 /* The stream ended before the image; this is the same as too few IDATs so
4290 * should be handled the same way.
4291 */
4292 if (output != NULL)
4293 png_error(png_ptr, "Not enough image data");
4294
4295 else /* the deflate stream contained extra data */
4296 png_chunk_benign_error(png_ptr, "Too much image data");
4297 }
4298 }
4299
4300 void /* PRIVATE */
4301 png_read_finish_IDAT(png_structrp png_ptr)
4302 {
4303 /* We don't need any more data and the stream should have ended, however the
4304 * LZ end code may actually not have been processed. In this case we must
4305 * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
4306 * may still remain to be consumed.
4307 */
4308 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
4309 {
4310 /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
4311 * the compressed stream, but the stream may be damaged too, so even after
4312 * this call we may need to terminate the zstream ownership.
4313 */
4314 png_read_IDAT_data(png_ptr, NULL, 0);
4315 png_ptr->zstream.next_out = NULL; /* safety */
4316
4317 /* Now clear everything out for safety; the following may not have been
4318 * done.
4319 */
4320 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
4321 {
4322 png_ptr->mode |= PNG_AFTER_IDAT;
4323 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4324 }
4325 }
4326
4327 /* If the zstream has not been released do it now *and* terminate the reading
4328 * of the final IDAT chunk.
4329 */
4330 if (png_ptr->zowner == png_IDAT)
4331 {
4332 /* Always do this; the pointers otherwise point into the read buffer. */
4333 png_ptr->zstream.next_in = NULL;
4334 png_ptr->zstream.avail_in = 0;
4335
4336 /* Now we no longer own the zstream. */
4337 png_ptr->zowner = 0;
4338
4339 /* The slightly weird semantics of the sequential IDAT reading is that we
4340 * are always in or at the end of an IDAT chunk, so we always need to do a
4341 * crc_finish here. If idat_size is non-zero we also need to read the
4342 * spurious bytes at the end of the chunk now.
4343 */
4344 (void)png_crc_finish(png_ptr, png_ptr->idat_size);
4345 }
4346 }
4347
4348 void /* PRIVATE */
4349 png_read_finish_row(png_structrp png_ptr)
4350 {
4351 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4352
4353 /* Start of interlace block */
4354 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4355
4356 /* Offset to next interlace block */
4357 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4358
4359 /* Start of interlace block in the y direction */
4360 static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4361
4362 /* Offset to next interlace block in the y direction */
4363 static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4364
4365 png_debug(1, "in png_read_finish_row");
4366 png_ptr->row_number++;
4367 if (png_ptr->row_number < png_ptr->num_rows)
4368 return;
4369
4370 if (png_ptr->interlaced != 0)
4371 {
4372 png_ptr->row_number = 0;
4373
4374 /* TO DO: don't do this if prev_row isn't needed (requires
4375 * read-ahead of the next row's filter byte.
4376 */
4377 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4378
4379 do
4380 {
4381 png_ptr->pass++;
4382
4383 if (png_ptr->pass >= 7)
4384 break;
4385
4386 png_ptr->iwidth = (png_ptr->width +
4387 png_pass_inc[png_ptr->pass] - 1 -
4388 png_pass_start[png_ptr->pass]) /
4389 png_pass_inc[png_ptr->pass];
4390
4391 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4392 {
4393 png_ptr->num_rows = (png_ptr->height +
4394 png_pass_yinc[png_ptr->pass] - 1 -
4395 png_pass_ystart[png_ptr->pass]) /
4396 png_pass_yinc[png_ptr->pass];
4397 }
4398
4399 else /* if (png_ptr->transformations & PNG_INTERLACE) */
4400 break; /* libpng deinterlacing sees every row */
4401
4402 } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
4403
4404 if (png_ptr->pass < 7)
4405 return;
4406 }
4407
4408 /* Here after at the end of the last row of the last pass. */
4409 png_read_finish_IDAT(png_ptr);
4410 }
4411 #endif /* SEQUENTIAL_READ */
4412
4413 void /* PRIVATE */
4414 png_read_start_row(png_structrp png_ptr)
4415 {
4416 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4417
4418 /* Start of interlace block */
4419 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4420
4421 /* Offset to next interlace block */
4422 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4423
4424 /* Start of interlace block in the y direction */
4425 static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4426
4427 /* Offset to next interlace block in the y direction */
4428 static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4429
4430 unsigned int max_pixel_depth;
4431 size_t row_bytes;
4432
4433 png_debug(1, "in png_read_start_row");
4434
4435 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
4436 png_init_read_transformations(png_ptr);
4437 #endif
4438 if (png_ptr->interlaced != 0)
4439 {
4440 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4441 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
4442 png_pass_ystart[0]) / png_pass_yinc[0];
4443
4444 else
4445 png_ptr->num_rows = png_ptr->height;
4446
4447 png_ptr->iwidth = (png_ptr->width +
4448 png_pass_inc[png_ptr->pass] - 1 -
4449 png_pass_start[png_ptr->pass]) /
4450 png_pass_inc[png_ptr->pass];
4451 }
4452
4453 else
4454 {
4455 png_ptr->num_rows = png_ptr->height;
4456 png_ptr->iwidth = png_ptr->width;
4457 }
4458
4459 max_pixel_depth = (unsigned int)png_ptr->pixel_depth;
4460
4461 /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of
4462 * calculations to calculate the final pixel depth, then
4463 * png_do_read_transforms actually does the transforms. This means that the
4464 * code which effectively calculates this value is actually repeated in three
4465 * separate places. They must all match. Innocent changes to the order of
4466 * transformations can and will break libpng in a way that causes memory
4467 * overwrites.
4468 *
4469 * TODO: fix this.
4470 */
4471 #ifdef PNG_READ_PACK_SUPPORTED
4472 if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8)
4473 max_pixel_depth = 8;
4474 #endif
4475
4476 #ifdef PNG_READ_EXPAND_SUPPORTED
4477 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4478 {
4479 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4480 {
4481 if (png_ptr->num_trans != 0)
4482 max_pixel_depth = 32;
4483
4484 else
4485 max_pixel_depth = 24;
4486 }
4487
4488 else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4489 {
4490 if (max_pixel_depth < 8)
4491 max_pixel_depth = 8;
4492
4493 if (png_ptr->num_trans != 0)
4494 max_pixel_depth *= 2;
4495 }
4496
4497 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
4498 {
4499 if (png_ptr->num_trans != 0)
4500 {
4501 max_pixel_depth *= 4;
4502 max_pixel_depth /= 3;
4503 }
4504 }
4505 }
4506 #endif
4507
4508 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4509 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4510 {
4511 # ifdef PNG_READ_EXPAND_SUPPORTED
4512 /* In fact it is an error if it isn't supported, but checking is
4513 * the safe way.
4514 */
4515 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4516 {
4517 if (png_ptr->bit_depth < 16)
4518 max_pixel_depth *= 2;
4519 }
4520 else
4521 # endif
4522 png_ptr->transformations &= ~PNG_EXPAND_16;
4523 }
4524 #endif
4525
4526 #ifdef PNG_READ_FILLER_SUPPORTED
4527 if ((png_ptr->transformations & (PNG_FILLER)) != 0)
4528 {
4529 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4530 {
4531 if (max_pixel_depth <= 8)
4532 max_pixel_depth = 16;
4533
4534 else
4535 max_pixel_depth = 32;
4536 }
4537
4538 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
4539 png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4540 {
4541 if (max_pixel_depth <= 32)
4542 max_pixel_depth = 32;
4543
4544 else
4545 max_pixel_depth = 64;
4546 }
4547 }
4548 #endif
4549
4550 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4551 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
4552 {
4553 if (
4554 #ifdef PNG_READ_EXPAND_SUPPORTED
4555 (png_ptr->num_trans != 0 &&
4556 (png_ptr->transformations & PNG_EXPAND) != 0) ||
4557 #endif
4558 #ifdef PNG_READ_FILLER_SUPPORTED
4559 (png_ptr->transformations & (PNG_FILLER)) != 0 ||
4560 #endif
4561 png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4562 {
4563 if (max_pixel_depth <= 16)
4564 max_pixel_depth = 32;
4565
4566 else
4567 max_pixel_depth = 64;
4568 }
4569
4570 else
4571 {
4572 if (max_pixel_depth <= 8)
4573 {
4574 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4575 max_pixel_depth = 32;
4576
4577 else
4578 max_pixel_depth = 24;
4579 }
4580
4581 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4582 max_pixel_depth = 64;
4583
4584 else
4585 max_pixel_depth = 48;
4586 }
4587 }
4588 #endif
4589
4590 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
4591 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
4592 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
4593 {
4594 unsigned int user_pixel_depth = png_ptr->user_transform_depth *
4595 png_ptr->user_transform_channels;
4596
4597 if (user_pixel_depth > max_pixel_depth)
4598 max_pixel_depth = user_pixel_depth;
4599 }
4600 #endif
4601
4602 /* This value is stored in png_struct and double checked in the row read
4603 * code.
4604 */
4605 png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
4606 png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
4607
4608 /* Align the width on the next larger 8 pixels. Mainly used
4609 * for interlacing
4610 */
4611 row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
4612 /* Calculate the maximum bytes needed, adding a byte and a pixel
4613 * for safety's sake
4614 */
4615 row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
4616 1 + ((max_pixel_depth + 7) >> 3U);
4617
4618 #ifdef PNG_MAX_MALLOC_64K
4619 if (row_bytes > (png_uint_32)65536L)
4620 png_error(png_ptr, "This image requires a row greater than 64KB");
4621 #endif
4622
4623 if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
4624 {
4625 png_free(png_ptr, png_ptr->big_row_buf);
4626 png_free(png_ptr, png_ptr->big_prev_row);
4627
4628 if (png_ptr->interlaced != 0)
4629 png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
4630 row_bytes + 48);
4631
4632 else
4633 png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4634
4635 png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4636
4637 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
4638 /* Use 16-byte aligned memory for row_buf with at least 16 bytes
4639 * of padding before and after row_buf; treat prev_row similarly.
4640 * NOTE: the alignment is to the start of the pixels, one beyond the start
4641 * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this
4642 * was incorrect; the filter byte was aligned, which had the exact
4643 * opposite effect of that intended.
4644 */
4645 {
4646 png_bytep temp = png_ptr->big_row_buf + 32;
4647 int extra = (int)((temp - (png_bytep)0) & 0x0f);
4648 png_ptr->row_buf = temp - extra - 1/*filter byte*/;
4649
4650 temp = png_ptr->big_prev_row + 32;
4651 extra = (int)((temp - (png_bytep)0) & 0x0f);
4652 png_ptr->prev_row = temp - extra - 1/*filter byte*/;
4653 }
4654
4655 #else
4656 /* Use 31 bytes of padding before and 17 bytes after row_buf. */
4657 png_ptr->row_buf = png_ptr->big_row_buf + 31;
4658 png_ptr->prev_row = png_ptr->big_prev_row + 31;
4659 #endif
4660 png_ptr->old_big_row_buf_size = row_bytes + 48;
4661 }
4662
4663 #ifdef PNG_MAX_MALLOC_64K
4664 if (png_ptr->rowbytes > 65535)
4665 png_error(png_ptr, "This image requires a row greater than 64KB");
4666
4667 #endif
4668 if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
4669 png_error(png_ptr, "Row has too many bytes to allocate in memory");
4670
4671 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4672
4673 png_debug1(3, "width = %u,", png_ptr->width);
4674 png_debug1(3, "height = %u,", png_ptr->height);
4675 png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
4676 png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
4677 png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
4678 png_debug1(3, "irowbytes = %lu",
4679 (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
4680
4681 /* The sequential reader needs a buffer for IDAT, but the progressive reader
4682 * does not, so free the read buffer now regardless; the sequential reader
4683 * reallocates it on demand.
4684 */
4685 if (png_ptr->read_buffer != NULL)
4686 {
4687 png_bytep buffer = png_ptr->read_buffer;
4688
4689 png_ptr->read_buffer_size = 0;
4690 png_ptr->read_buffer = NULL;
4691 png_free(png_ptr, buffer);
4692 }
4693
4694 /* Finally claim the zstream for the inflate of the IDAT data, use the bits
4695 * value from the stream (note that this will result in a fatal error if the
4696 * IDAT stream has a bogus deflate header window_bits value, but this should
4697 * not be happening any longer!)
4698 */
4699 if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
4700 png_error(png_ptr, png_ptr->zstream.msg);
4701
4702 png_ptr->flags |= PNG_FLAG_ROW_INIT;
4703 }
4704 #endif /* READ */