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