1
2 /* pngrutil.c - utilities to read a PNG file
3 *
4 * Copyright (c) 2018-2024 Cosmin Truta
5 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6 * Copyright (c) 1996-1997 Andreas Dilger
7 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 *
13 * This file contains routines that are only called from within
14 * libpng itself during the course of reading an image.
15 */
16
17 #include "pngpriv.h"
18
19 #ifdef PNG_READ_SUPPORTED
20
21 png_uint_32 PNGAPI
png_get_uint_31(png_const_structrp png_ptr,png_const_bytep buf)22 png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
23 {
24 png_uint_32 uval = png_get_uint_32(buf);
25
26 if (uval > PNG_UINT_31_MAX)
27 png_error(png_ptr, "PNG unsigned integer out of range");
28
29 return uval;
30 }
31
32 #if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
33 /* The following is a variation on the above for use with the fixed
34 * point values used for gAMA and cHRM. Instead of png_error it
35 * issues a warning and returns (-1) - an invalid value because both
36 * gAMA and cHRM use *unsigned* integers for fixed point values.
37 */
38 #define PNG_FIXED_ERROR (-1)
39
40 static png_fixed_point /* PRIVATE */
png_get_fixed_point(png_structrp png_ptr,png_const_bytep buf)41 png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
42 {
43 png_uint_32 uval = png_get_uint_32(buf);
44
45 if (uval <= PNG_UINT_31_MAX)
46 return (png_fixed_point)uval; /* known to be in range */
47
48 /* The caller can turn off the warning by passing NULL. */
49 if (png_ptr != NULL)
50 png_warning(png_ptr, "PNG fixed point integer out of range");
51
52 return PNG_FIXED_ERROR;
53 }
54 #endif
55
56 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
57 /* NOTE: the read macros will obscure these definitions, so that if
58 * PNG_USE_READ_MACROS is set the library will not use them internally,
59 * but the APIs will still be available externally.
60 *
61 * The parentheses around "PNGAPI function_name" in the following three
62 * functions are necessary because they allow the macros to co-exist with
63 * these (unused but exported) functions.
64 */
65
66 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
png_uint_32(PNGAPI png_get_uint_32)67 png_uint_32 (PNGAPI
68 png_get_uint_32)(png_const_bytep buf)
69 {
70 png_uint_32 uval =
71 ((png_uint_32)(*(buf )) << 24) +
72 ((png_uint_32)(*(buf + 1)) << 16) +
73 ((png_uint_32)(*(buf + 2)) << 8) +
74 ((png_uint_32)(*(buf + 3)) ) ;
75
76 return uval;
77 }
78
79 /* Grab a signed 32-bit integer from a buffer in big-endian format. The
80 * data is stored in the PNG file in two's complement format and there
81 * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
82 * the following code does a two's complement to native conversion.
83 */
png_int_32(PNGAPI png_get_int_32)84 png_int_32 (PNGAPI
85 png_get_int_32)(png_const_bytep buf)
86 {
87 png_uint_32 uval = png_get_uint_32(buf);
88 if ((uval & 0x80000000) == 0) /* non-negative */
89 return (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. */
png_uint_16(PNGAPI png_get_uint_16)102 png_uint_16 (PNGAPI
103 png_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 */
120 void /* PRIVATE */
png_read_sig(png_structrp png_ptr,png_inforp info_ptr)121 png_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) != 0)
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 */
155 png_uint_32 /* PRIVATE */
png_read_chunk_header(png_structrp png_ptr)156 png_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 chunk typeid = 0x%lx, 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. */
195 void /* PRIVATE */
png_crc_read(png_structrp png_ptr,png_bytep buf,png_uint_32 length)196 png_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 */
210 int /* PRIVATE */
png_crc_finish(png_structrp png_ptr,png_uint_32 skip)211 png_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 */
250 int /* PRIVATE */
png_crc_error(png_structrp png_ptr)251 png_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 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 */
297 static png_bytep
png_read_buffer(png_structrp png_ptr,png_alloc_size_t new_size,int warn)298 png_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_size = 0;
306 png_free(png_ptr, buffer);
307 buffer = NULL;
308 }
309
310 if (buffer == NULL)
311 {
312 buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
313
314 if (buffer != NULL)
315 {
316 memset(buffer, 0, new_size); /* just in case */
317 png_ptr->read_buffer = buffer;
318 png_ptr->read_buffer_size = new_size;
319 }
320
321 else if (warn < 2) /* else silent */
322 {
323 if (warn != 0)
324 png_chunk_warning(png_ptr, "insufficient memory to read chunk");
325
326 else
327 png_chunk_error(png_ptr, "insufficient memory to read chunk");
328 }
329 }
330
331 return buffer;
332 }
333 #endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
334
335 /* png_inflate_claim: claim the zstream for some nefarious purpose that involves
336 * decompression. Returns Z_OK on success, else a zlib error code. It checks
337 * the owner but, in final release builds, just issues a warning if some other
338 * chunk apparently owns the stream. Prior to release it does a png_error.
339 */
340 static int
png_inflate_claim(png_structrp png_ptr,png_uint_32 owner)341 png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
342 {
343 if (png_ptr->zowner != 0)
344 {
345 char msg[64];
346
347 PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
348 /* So the message that results is "<chunk> using zstream"; this is an
349 * internal error, but is very useful for debugging. i18n requirements
350 * are minimal.
351 */
352 (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
353 #if PNG_RELEASE_BUILD
354 png_chunk_warning(png_ptr, msg);
355 png_ptr->zowner = 0;
356 #else
357 png_chunk_error(png_ptr, msg);
358 #endif
359 }
360
361 /* Implementation note: unlike 'png_deflate_claim' this internal function
362 * does not take the size of the data as an argument. Some efficiency could
363 * be gained by using this when it is known *if* the zlib stream itself does
364 * not record the number; however, this is an illusion: the original writer
365 * of the PNG may have selected a lower window size, and we really must
366 * follow that because, for systems with with limited capabilities, we
367 * would otherwise reject the application's attempts to use a smaller window
368 * size (zlib doesn't have an interface to say "this or lower"!).
369 *
370 * inflateReset2 was added to zlib 1.2.4; before this the window could not be
371 * reset, therefore it is necessary to always allocate the maximum window
372 * size with earlier zlibs just in case later compressed chunks need it.
373 */
374 {
375 int ret; /* zlib return code */
376 #if ZLIB_VERNUM >= 0x1240
377 int window_bits = 0;
378
379 # if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
380 if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
381 PNG_OPTION_ON)
382 {
383 window_bits = 15;
384 png_ptr->zstream_start = 0; /* fixed window size */
385 }
386
387 else
388 {
389 png_ptr->zstream_start = 1;
390 }
391 # endif
392
393 #endif /* ZLIB_VERNUM >= 0x1240 */
394
395 /* Set this for safety, just in case the previous owner left pointers to
396 * memory allocations.
397 */
398 png_ptr->zstream.next_in = NULL;
399 png_ptr->zstream.avail_in = 0;
400 png_ptr->zstream.next_out = NULL;
401 png_ptr->zstream.avail_out = 0;
402
403 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
404 {
405 #if ZLIB_VERNUM >= 0x1240
406 ret = inflateReset2(&png_ptr->zstream, window_bits);
407 #else
408 ret = inflateReset(&png_ptr->zstream);
409 #endif
410 }
411
412 else
413 {
414 #if ZLIB_VERNUM >= 0x1240
415 ret = inflateInit2(&png_ptr->zstream, window_bits);
416 #else
417 ret = inflateInit(&png_ptr->zstream);
418 #endif
419
420 if (ret == Z_OK)
421 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
422 }
423
424 #ifdef PNG_DISABLE_ADLER32_CHECK_SUPPORTED
425 if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON)
426 /* Turn off validation of the ADLER32 checksum in IDAT chunks */
427 ret = inflateValidate(&png_ptr->zstream, 0);
428 #endif
429
430 if (ret == Z_OK)
431 png_ptr->zowner = owner;
432
433 else
434 png_zstream_error(png_ptr, ret);
435
436 return ret;
437 }
438
439 #ifdef window_bits
440 # undef window_bits
441 #endif
442 }
443
444 #if ZLIB_VERNUM >= 0x1240
445 /* Handle the start of the inflate stream if we called inflateInit2(strm,0);
446 * in this case some zlib versions skip validation of the CINFO field and, in
447 * certain circumstances, libpng may end up displaying an invalid image, in
448 * contrast to implementations that call zlib in the normal way (e.g. libpng
449 * 1.5).
450 */
451 int /* PRIVATE */
png_zlib_inflate(png_structrp png_ptr,int flush)452 png_zlib_inflate(png_structrp png_ptr, int flush)
453 {
454 if (png_ptr->zstream_start && png_ptr->zstream.avail_in > 0)
455 {
456 if ((*png_ptr->zstream.next_in >> 4) > 7)
457 {
458 png_ptr->zstream.msg = "invalid window size (libpng)";
459 return Z_DATA_ERROR;
460 }
461
462 png_ptr->zstream_start = 0;
463 }
464
465 return inflate(&png_ptr->zstream, flush);
466 }
467 #endif /* Zlib >= 1.2.4 */
468
469 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
470 #if defined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED)
471 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
472 * allow the caller to do multiple calls if required. If the 'finish' flag is
473 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
474 * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
475 * Z_OK or Z_STREAM_END will be returned on success.
476 *
477 * The input and output sizes are updated to the actual amounts of data consumed
478 * or written, not the amount available (as in a z_stream). The data pointers
479 * are not changed, so the next input is (data+input_size) and the next
480 * available output is (output+output_size).
481 */
482 static int
png_inflate(png_structrp png_ptr,png_uint_32 owner,int finish,png_const_bytep input,png_uint_32p input_size_ptr,png_bytep output,png_alloc_size_t * output_size_ptr)483 png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
484 /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
485 /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
486 {
487 if (png_ptr->zowner == owner) /* Else not claimed */
488 {
489 int ret;
490 png_alloc_size_t avail_out = *output_size_ptr;
491 png_uint_32 avail_in = *input_size_ptr;
492
493 /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
494 * can't even necessarily handle 65536 bytes) because the type uInt is
495 * "16 bits or more". Consequently it is necessary to chunk the input to
496 * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
497 * maximum value that can be stored in a uInt.) It is possible to set
498 * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
499 * a performance advantage, because it reduces the amount of data accessed
500 * at each step and that may give the OS more time to page it in.
501 */
502 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
503 /* avail_in and avail_out are set below from 'size' */
504 png_ptr->zstream.avail_in = 0;
505 png_ptr->zstream.avail_out = 0;
506
507 /* Read directly into the output if it is available (this is set to
508 * a local buffer below if output is NULL).
509 */
510 if (output != NULL)
511 png_ptr->zstream.next_out = output;
512
513 do
514 {
515 uInt avail;
516 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
517
518 /* zlib INPUT BUFFER */
519 /* The setting of 'avail_in' used to be outside the loop; by setting it
520 * inside it is possible to chunk the input to zlib and simply rely on
521 * zlib to advance the 'next_in' pointer. This allows arbitrary
522 * amounts of data to be passed through zlib at the unavoidable cost of
523 * requiring a window save (memcpy of up to 32768 output bytes)
524 * every ZLIB_IO_MAX input bytes.
525 */
526 avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
527
528 avail = ZLIB_IO_MAX;
529
530 if (avail_in < avail)
531 avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
532
533 avail_in -= avail;
534 png_ptr->zstream.avail_in = avail;
535
536 /* zlib OUTPUT BUFFER */
537 avail_out += png_ptr->zstream.avail_out; /* not written last time */
538
539 avail = ZLIB_IO_MAX; /* maximum zlib can process */
540
541 if (output == NULL)
542 {
543 /* Reset the output buffer each time round if output is NULL and
544 * make available the full buffer, up to 'remaining_space'
545 */
546 png_ptr->zstream.next_out = local_buffer;
547 if ((sizeof local_buffer) < avail)
548 avail = (sizeof local_buffer);
549 }
550
551 if (avail_out < avail)
552 avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
553
554 png_ptr->zstream.avail_out = avail;
555 avail_out -= avail;
556
557 /* zlib inflate call */
558 /* In fact 'avail_out' may be 0 at this point, that happens at the end
559 * of the read when the final LZ end code was not passed at the end of
560 * the previous chunk of input data. Tell zlib if we have reached the
561 * end of the output buffer.
562 */
563 ret = PNG_INFLATE(png_ptr, avail_out > 0 ? Z_NO_FLUSH :
564 (finish ? Z_FINISH : Z_SYNC_FLUSH));
565 } while (ret == Z_OK);
566
567 /* For safety kill the local buffer pointer now */
568 if (output == NULL)
569 png_ptr->zstream.next_out = NULL;
570
571 /* Claw back the 'size' and 'remaining_space' byte counts. */
572 avail_in += png_ptr->zstream.avail_in;
573 avail_out += png_ptr->zstream.avail_out;
574
575 /* Update the input and output sizes; the updated values are the amount
576 * consumed or written, effectively the inverse of what zlib uses.
577 */
578 if (avail_out > 0)
579 *output_size_ptr -= avail_out;
580
581 if (avail_in > 0)
582 *input_size_ptr -= avail_in;
583
584 /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
585 png_zstream_error(png_ptr, ret);
586 return ret;
587 }
588
589 else
590 {
591 /* This is a bad internal error. The recovery assigns to the zstream msg
592 * pointer, which is not owned by the caller, but this is safe; it's only
593 * used on errors!
594 */
595 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
596 return Z_STREAM_ERROR;
597 }
598 }
599
600 /*
601 * Decompress trailing data in a chunk. The assumption is that read_buffer
602 * points at an allocated area holding the contents of a chunk with a
603 * trailing compressed part. What we get back is an allocated area
604 * holding the original prefix part and an uncompressed version of the
605 * trailing part (the malloc area passed in is freed).
606 */
607 static int
png_decompress_chunk(png_structrp png_ptr,png_uint_32 chunklength,png_uint_32 prefix_size,png_alloc_size_t * newlength,int terminate)608 png_decompress_chunk(png_structrp png_ptr,
609 png_uint_32 chunklength, png_uint_32 prefix_size,
610 png_alloc_size_t *newlength /* must be initialized to the maximum! */,
611 int terminate /*add a '\0' to the end of the uncompressed data*/)
612 {
613 /* TODO: implement different limits for different types of chunk.
614 *
615 * The caller supplies *newlength set to the maximum length of the
616 * uncompressed data, but this routine allocates space for the prefix and
617 * maybe a '\0' terminator too. We have to assume that 'prefix_size' is
618 * limited only by the maximum chunk size.
619 */
620 png_alloc_size_t limit = PNG_SIZE_MAX;
621
622 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
623 if (png_ptr->user_chunk_malloc_max > 0 &&
624 png_ptr->user_chunk_malloc_max < limit)
625 limit = png_ptr->user_chunk_malloc_max;
626 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
627 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
628 limit = PNG_USER_CHUNK_MALLOC_MAX;
629 # endif
630
631 if (limit >= prefix_size + (terminate != 0))
632 {
633 int ret;
634
635 limit -= prefix_size + (terminate != 0);
636
637 if (limit < *newlength)
638 *newlength = limit;
639
640 /* Now try to claim the stream. */
641 ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
642
643 if (ret == Z_OK)
644 {
645 png_uint_32 lzsize = chunklength - prefix_size;
646
647 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
648 /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
649 /* output: */ NULL, newlength);
650
651 if (ret == Z_STREAM_END)
652 {
653 /* Use 'inflateReset' here, not 'inflateReset2' because this
654 * preserves the previously decided window size (otherwise it would
655 * be necessary to store the previous window size.) In practice
656 * this doesn't matter anyway, because png_inflate will call inflate
657 * with Z_FINISH in almost all cases, so the window will not be
658 * maintained.
659 */
660 if (inflateReset(&png_ptr->zstream) == Z_OK)
661 {
662 /* Because of the limit checks above we know that the new,
663 * expanded, size will fit in a size_t (let alone an
664 * png_alloc_size_t). Use png_malloc_base here to avoid an
665 * extra OOM message.
666 */
667 png_alloc_size_t new_size = *newlength;
668 png_alloc_size_t buffer_size = prefix_size + new_size +
669 (terminate != 0);
670 png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
671 buffer_size));
672
673 if (text != NULL)
674 {
675 memset(text, 0, buffer_size);
676
677 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
678 png_ptr->read_buffer + prefix_size, &lzsize,
679 text + prefix_size, newlength);
680
681 if (ret == Z_STREAM_END)
682 {
683 if (new_size == *newlength)
684 {
685 if (terminate != 0)
686 text[prefix_size + *newlength] = 0;
687
688 if (prefix_size > 0)
689 memcpy(text, png_ptr->read_buffer, prefix_size);
690
691 {
692 png_bytep old_ptr = png_ptr->read_buffer;
693
694 png_ptr->read_buffer = text;
695 png_ptr->read_buffer_size = buffer_size;
696 text = old_ptr; /* freed below */
697 }
698 }
699
700 else
701 {
702 /* The size changed on the second read, there can be no
703 * guarantee that anything is correct at this point.
704 * The 'msg' pointer has been set to "unexpected end of
705 * LZ stream", which is fine, but return an error code
706 * that the caller won't accept.
707 */
708 ret = PNG_UNEXPECTED_ZLIB_RETURN;
709 }
710 }
711
712 else if (ret == Z_OK)
713 ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
714
715 /* Free the text pointer (this is the old read_buffer on
716 * success)
717 */
718 png_free(png_ptr, text);
719
720 /* This really is very benign, but it's still an error because
721 * the extra space may otherwise be used as a Trojan Horse.
722 */
723 if (ret == Z_STREAM_END &&
724 chunklength - prefix_size != lzsize)
725 png_chunk_benign_error(png_ptr, "extra compressed data");
726 }
727
728 else
729 {
730 /* Out of memory allocating the buffer */
731 ret = Z_MEM_ERROR;
732 png_zstream_error(png_ptr, Z_MEM_ERROR);
733 }
734 }
735
736 else
737 {
738 /* inflateReset failed, store the error message */
739 png_zstream_error(png_ptr, ret);
740 ret = PNG_UNEXPECTED_ZLIB_RETURN;
741 }
742 }
743
744 else if (ret == Z_OK)
745 ret = PNG_UNEXPECTED_ZLIB_RETURN;
746
747 /* Release the claimed stream */
748 png_ptr->zowner = 0;
749 }
750
751 else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
752 ret = PNG_UNEXPECTED_ZLIB_RETURN;
753
754 return ret;
755 }
756
757 else
758 {
759 /* Application/configuration limits exceeded */
760 png_zstream_error(png_ptr, Z_MEM_ERROR);
761 return Z_MEM_ERROR;
762 }
763 }
764 #endif /* READ_zTXt || READ_iTXt */
765 #endif /* READ_COMPRESSED_TEXT */
766
767 #ifdef PNG_READ_iCCP_SUPPORTED
768 /* Perform a partial read and decompress, producing 'avail_out' bytes and
769 * reading from the current chunk as required.
770 */
771 static int
png_inflate_read(png_structrp png_ptr,png_bytep read_buffer,uInt read_size,png_uint_32p chunk_bytes,png_bytep next_out,png_alloc_size_t * out_size,int finish)772 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
773 png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
774 int finish)
775 {
776 if (png_ptr->zowner == png_ptr->chunk_name)
777 {
778 int ret;
779
780 /* next_in and avail_in must have been initialized by the caller. */
781 png_ptr->zstream.next_out = next_out;
782 png_ptr->zstream.avail_out = 0; /* set in the loop */
783
784 do
785 {
786 if (png_ptr->zstream.avail_in == 0)
787 {
788 if (read_size > *chunk_bytes)
789 read_size = (uInt)*chunk_bytes;
790 *chunk_bytes -= read_size;
791
792 if (read_size > 0)
793 png_crc_read(png_ptr, read_buffer, read_size);
794
795 png_ptr->zstream.next_in = read_buffer;
796 png_ptr->zstream.avail_in = read_size;
797 }
798
799 if (png_ptr->zstream.avail_out == 0)
800 {
801 uInt avail = ZLIB_IO_MAX;
802 if (avail > *out_size)
803 avail = (uInt)*out_size;
804 *out_size -= avail;
805
806 png_ptr->zstream.avail_out = avail;
807 }
808
809 /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
810 * the available output is produced; this allows reading of truncated
811 * streams.
812 */
813 ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ?
814 Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
815 }
816 while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
817
818 *out_size += png_ptr->zstream.avail_out;
819 png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
820
821 /* Ensure the error message pointer is always set: */
822 png_zstream_error(png_ptr, ret);
823 return ret;
824 }
825
826 else
827 {
828 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
829 return Z_STREAM_ERROR;
830 }
831 }
832 #endif /* READ_iCCP */
833
834 /* Read and check the IDHR chunk */
835
836 void /* PRIVATE */
png_handle_IHDR(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)837 png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
838 {
839 png_byte buf[13];
840 png_uint_32 width, height;
841 int bit_depth, color_type, compression_type, filter_type;
842 int interlace_type;
843
844 png_debug(1, "in png_handle_IHDR");
845
846 if ((png_ptr->mode & PNG_HAVE_IHDR) != 0)
847 png_chunk_error(png_ptr, "out of place");
848
849 /* Check the length */
850 if (length != 13)
851 png_chunk_error(png_ptr, "invalid");
852
853 png_ptr->mode |= PNG_HAVE_IHDR;
854
855 png_crc_read(png_ptr, buf, 13);
856 png_crc_finish(png_ptr, 0);
857
858 width = png_get_uint_31(png_ptr, buf);
859 height = png_get_uint_31(png_ptr, buf + 4);
860 bit_depth = buf[8];
861 color_type = buf[9];
862 compression_type = buf[10];
863 filter_type = buf[11];
864 interlace_type = buf[12];
865
866 /* Set internal variables */
867 png_ptr->width = width;
868 png_ptr->height = height;
869 png_ptr->bit_depth = (png_byte)bit_depth;
870 png_ptr->interlaced = (png_byte)interlace_type;
871 png_ptr->color_type = (png_byte)color_type;
872 #ifdef PNG_MNG_FEATURES_SUPPORTED
873 png_ptr->filter_type = (png_byte)filter_type;
874 #endif
875 png_ptr->compression_type = (png_byte)compression_type;
876
877 /* Find number of channels */
878 switch (png_ptr->color_type)
879 {
880 default: /* invalid, png_set_IHDR calls png_error */
881 case PNG_COLOR_TYPE_GRAY:
882 case PNG_COLOR_TYPE_PALETTE:
883 png_ptr->channels = 1;
884 break;
885
886 case PNG_COLOR_TYPE_RGB:
887 png_ptr->channels = 3;
888 break;
889
890 case PNG_COLOR_TYPE_GRAY_ALPHA:
891 png_ptr->channels = 2;
892 break;
893
894 case PNG_COLOR_TYPE_RGB_ALPHA:
895 png_ptr->channels = 4;
896 break;
897 }
898
899 /* Set up other useful info */
900 png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels);
901 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
902 png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
903 png_debug1(3, "channels = %d", png_ptr->channels);
904 png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
905 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
906 color_type, interlace_type, compression_type, filter_type);
907 }
908
909 /* Read and check the palette */
910 void /* PRIVATE */
png_handle_PLTE(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)911 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
912 {
913 png_color palette[PNG_MAX_PALETTE_LENGTH];
914 int max_palette_length, num, i;
915 #ifdef PNG_POINTER_INDEXING_SUPPORTED
916 png_colorp pal_ptr;
917 #endif
918
919 png_debug(1, "in png_handle_PLTE");
920
921 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
922 png_chunk_error(png_ptr, "missing IHDR");
923
924 /* Moved to before the 'after IDAT' check below because otherwise duplicate
925 * PLTE chunks are potentially ignored (the spec says there shall not be more
926 * than one PLTE, the error is not treated as benign, so this check trumps
927 * the requirement that PLTE appears before IDAT.)
928 */
929 else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
930 png_chunk_error(png_ptr, "duplicate");
931
932 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
933 {
934 /* This is benign because the non-benign error happened before, when an
935 * IDAT was encountered in a color-mapped image with no PLTE.
936 */
937 png_crc_finish(png_ptr, length);
938 png_chunk_benign_error(png_ptr, "out of place");
939 return;
940 }
941
942 png_ptr->mode |= PNG_HAVE_PLTE;
943
944 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
945 {
946 png_crc_finish(png_ptr, length);
947 png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
948 return;
949 }
950
951 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
952 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
953 {
954 png_crc_finish(png_ptr, length);
955 return;
956 }
957 #endif
958
959 if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
960 {
961 png_crc_finish(png_ptr, length);
962
963 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
964 png_chunk_benign_error(png_ptr, "invalid");
965
966 else
967 png_chunk_error(png_ptr, "invalid");
968
969 return;
970 }
971
972 /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
973 num = (int)length / 3;
974
975 /* If the palette has 256 or fewer entries but is too large for the bit
976 * depth, we don't issue an error, to preserve the behavior of previous
977 * libpng versions. We silently truncate the unused extra palette entries
978 * here.
979 */
980 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
981 max_palette_length = (1 << png_ptr->bit_depth);
982 else
983 max_palette_length = PNG_MAX_PALETTE_LENGTH;
984
985 if (num > max_palette_length)
986 num = max_palette_length;
987
988 #ifdef PNG_POINTER_INDEXING_SUPPORTED
989 for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
990 {
991 png_byte buf[3];
992
993 png_crc_read(png_ptr, buf, 3);
994 pal_ptr->red = buf[0];
995 pal_ptr->green = buf[1];
996 pal_ptr->blue = buf[2];
997 }
998 #else
999 for (i = 0; i < num; i++)
1000 {
1001 png_byte buf[3];
1002
1003 png_crc_read(png_ptr, buf, 3);
1004 /* Don't depend upon png_color being any order */
1005 palette[i].red = buf[0];
1006 palette[i].green = buf[1];
1007 palette[i].blue = buf[2];
1008 }
1009 #endif
1010
1011 /* If we actually need the PLTE chunk (ie for a paletted image), we do
1012 * whatever the normal CRC configuration tells us. However, if we
1013 * have an RGB image, the PLTE can be considered ancillary, so
1014 * we will act as though it is.
1015 */
1016 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1017 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1018 #endif
1019 {
1020 png_crc_finish(png_ptr, (png_uint_32) (length - (unsigned int)num * 3));
1021 }
1022
1023 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1024 else if (png_crc_error(png_ptr) != 0) /* Only if we have a CRC error */
1025 {
1026 /* If we don't want to use the data from an ancillary chunk,
1027 * we have two options: an error abort, or a warning and we
1028 * ignore the data in this chunk (which should be OK, since
1029 * it's considered ancillary for a RGB or RGBA image).
1030 *
1031 * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
1032 * chunk type to determine whether to check the ancillary or the critical
1033 * flags.
1034 */
1035 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
1036 {
1037 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0)
1038 return;
1039
1040 else
1041 png_chunk_error(png_ptr, "CRC error");
1042 }
1043
1044 /* Otherwise, we (optionally) emit a warning and use the chunk. */
1045 else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
1046 png_chunk_warning(png_ptr, "CRC error");
1047 }
1048 #endif
1049
1050 /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
1051 * own copy of the palette. This has the side effect that when png_start_row
1052 * is called (this happens after any call to png_read_update_info) the
1053 * info_ptr palette gets changed. This is extremely unexpected and
1054 * confusing.
1055 *
1056 * Fix this by not sharing the palette in this way.
1057 */
1058 png_set_PLTE(png_ptr, info_ptr, palette, num);
1059
1060 /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
1061 * IDAT. Prior to 1.6.0 this was not checked; instead the code merely
1062 * checked the apparent validity of a tRNS chunk inserted before PLTE on a
1063 * palette PNG. 1.6.0 attempts to rigorously follow the standard and
1064 * therefore does a benign error if the erroneous condition is detected *and*
1065 * cancels the tRNS if the benign error returns. The alternative is to
1066 * amend the standard since it would be rather hypocritical of the standards
1067 * maintainers to ignore it.
1068 */
1069 #ifdef PNG_READ_tRNS_SUPPORTED
1070 if (png_ptr->num_trans > 0 ||
1071 (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
1072 {
1073 /* Cancel this because otherwise it would be used if the transforms
1074 * require it. Don't cancel the 'valid' flag because this would prevent
1075 * detection of duplicate chunks.
1076 */
1077 png_ptr->num_trans = 0;
1078
1079 if (info_ptr != NULL)
1080 info_ptr->num_trans = 0;
1081
1082 png_chunk_benign_error(png_ptr, "tRNS must be after");
1083 }
1084 #endif
1085
1086 #ifdef PNG_READ_hIST_SUPPORTED
1087 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
1088 png_chunk_benign_error(png_ptr, "hIST must be after");
1089 #endif
1090
1091 #ifdef PNG_READ_bKGD_SUPPORTED
1092 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1093 png_chunk_benign_error(png_ptr, "bKGD must be after");
1094 #endif
1095 }
1096
1097 void /* PRIVATE */
png_handle_IEND(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1098 png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1099 {
1100 png_debug(1, "in png_handle_IEND");
1101
1102 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0 ||
1103 (png_ptr->mode & PNG_HAVE_IDAT) == 0)
1104 png_chunk_error(png_ptr, "out of place");
1105
1106 png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
1107
1108 png_crc_finish(png_ptr, length);
1109
1110 if (length != 0)
1111 png_chunk_benign_error(png_ptr, "invalid");
1112
1113 PNG_UNUSED(info_ptr)
1114 }
1115
1116 #ifdef PNG_READ_gAMA_SUPPORTED
1117 void /* PRIVATE */
png_handle_gAMA(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1118 png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1119 {
1120 png_fixed_point igamma;
1121 png_byte buf[4];
1122
1123 png_debug(1, "in png_handle_gAMA");
1124
1125 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1126 png_chunk_error(png_ptr, "missing IHDR");
1127
1128 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1129 {
1130 png_crc_finish(png_ptr, length);
1131 png_chunk_benign_error(png_ptr, "out of place");
1132 return;
1133 }
1134
1135 if (length != 4)
1136 {
1137 png_crc_finish(png_ptr, length);
1138 png_chunk_benign_error(png_ptr, "invalid");
1139 return;
1140 }
1141
1142 png_crc_read(png_ptr, buf, 4);
1143
1144 if (png_crc_finish(png_ptr, 0) != 0)
1145 return;
1146
1147 igamma = png_get_fixed_point(NULL, buf);
1148
1149 png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
1150 png_colorspace_sync(png_ptr, info_ptr);
1151 }
1152 #endif
1153
1154 #ifdef PNG_READ_sBIT_SUPPORTED
1155 void /* PRIVATE */
png_handle_sBIT(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1156 png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1157 {
1158 unsigned int truelen, i;
1159 png_byte sample_depth;
1160 png_byte buf[4];
1161
1162 png_debug(1, "in png_handle_sBIT");
1163
1164 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1165 png_chunk_error(png_ptr, "missing IHDR");
1166
1167 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1168 {
1169 png_crc_finish(png_ptr, length);
1170 png_chunk_benign_error(png_ptr, "out of place");
1171 return;
1172 }
1173
1174 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT) != 0)
1175 {
1176 png_crc_finish(png_ptr, length);
1177 png_chunk_benign_error(png_ptr, "duplicate");
1178 return;
1179 }
1180
1181 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1182 {
1183 truelen = 3;
1184 sample_depth = 8;
1185 }
1186
1187 else
1188 {
1189 truelen = png_ptr->channels;
1190 sample_depth = png_ptr->bit_depth;
1191 }
1192
1193 if (length != truelen || length > 4)
1194 {
1195 png_chunk_benign_error(png_ptr, "invalid");
1196 png_crc_finish(png_ptr, length);
1197 return;
1198 }
1199
1200 buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
1201 png_crc_read(png_ptr, buf, truelen);
1202
1203 if (png_crc_finish(png_ptr, 0) != 0)
1204 return;
1205
1206 for (i=0; i<truelen; ++i)
1207 {
1208 if (buf[i] == 0 || buf[i] > sample_depth)
1209 {
1210 png_chunk_benign_error(png_ptr, "invalid");
1211 return;
1212 }
1213 }
1214
1215 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1216 {
1217 png_ptr->sig_bit.red = buf[0];
1218 png_ptr->sig_bit.green = buf[1];
1219 png_ptr->sig_bit.blue = buf[2];
1220 png_ptr->sig_bit.alpha = buf[3];
1221 }
1222
1223 else
1224 {
1225 png_ptr->sig_bit.gray = buf[0];
1226 png_ptr->sig_bit.red = buf[0];
1227 png_ptr->sig_bit.green = buf[0];
1228 png_ptr->sig_bit.blue = buf[0];
1229 png_ptr->sig_bit.alpha = buf[1];
1230 }
1231
1232 png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
1233 }
1234 #endif
1235
1236 #ifdef PNG_READ_cHRM_SUPPORTED
1237 void /* PRIVATE */
png_handle_cHRM(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1238 png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1239 {
1240 png_byte buf[32];
1241 png_xy xy;
1242
1243 png_debug(1, "in png_handle_cHRM");
1244
1245 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1246 png_chunk_error(png_ptr, "missing IHDR");
1247
1248 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1249 {
1250 png_crc_finish(png_ptr, length);
1251 png_chunk_benign_error(png_ptr, "out of place");
1252 return;
1253 }
1254
1255 if (length != 32)
1256 {
1257 png_crc_finish(png_ptr, length);
1258 png_chunk_benign_error(png_ptr, "invalid");
1259 return;
1260 }
1261
1262 png_crc_read(png_ptr, buf, 32);
1263
1264 if (png_crc_finish(png_ptr, 0) != 0)
1265 return;
1266
1267 xy.whitex = png_get_fixed_point(NULL, buf);
1268 xy.whitey = png_get_fixed_point(NULL, buf + 4);
1269 xy.redx = png_get_fixed_point(NULL, buf + 8);
1270 xy.redy = png_get_fixed_point(NULL, buf + 12);
1271 xy.greenx = png_get_fixed_point(NULL, buf + 16);
1272 xy.greeny = png_get_fixed_point(NULL, buf + 20);
1273 xy.bluex = png_get_fixed_point(NULL, buf + 24);
1274 xy.bluey = png_get_fixed_point(NULL, buf + 28);
1275
1276 if (xy.whitex == PNG_FIXED_ERROR ||
1277 xy.whitey == PNG_FIXED_ERROR ||
1278 xy.redx == PNG_FIXED_ERROR ||
1279 xy.redy == PNG_FIXED_ERROR ||
1280 xy.greenx == PNG_FIXED_ERROR ||
1281 xy.greeny == PNG_FIXED_ERROR ||
1282 xy.bluex == PNG_FIXED_ERROR ||
1283 xy.bluey == PNG_FIXED_ERROR)
1284 {
1285 png_chunk_benign_error(png_ptr, "invalid values");
1286 return;
1287 }
1288
1289 /* If a colorspace error has already been output skip this chunk */
1290 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1291 return;
1292
1293 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0)
1294 {
1295 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1296 png_colorspace_sync(png_ptr, info_ptr);
1297 png_chunk_benign_error(png_ptr, "duplicate");
1298 return;
1299 }
1300
1301 png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
1302 (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1303 1/*prefer cHRM values*/);
1304 png_colorspace_sync(png_ptr, info_ptr);
1305 }
1306 #endif
1307
1308 #ifdef PNG_READ_sRGB_SUPPORTED
1309 void /* PRIVATE */
png_handle_sRGB(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1310 png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1311 {
1312 png_byte intent;
1313
1314 png_debug(1, "in png_handle_sRGB");
1315
1316 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1317 png_chunk_error(png_ptr, "missing IHDR");
1318
1319 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1320 {
1321 png_crc_finish(png_ptr, length);
1322 png_chunk_benign_error(png_ptr, "out of place");
1323 return;
1324 }
1325
1326 if (length != 1)
1327 {
1328 png_crc_finish(png_ptr, length);
1329 png_chunk_benign_error(png_ptr, "invalid");
1330 return;
1331 }
1332
1333 png_crc_read(png_ptr, &intent, 1);
1334
1335 if (png_crc_finish(png_ptr, 0) != 0)
1336 return;
1337
1338 /* If a colorspace error has already been output skip this chunk */
1339 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1340 return;
1341
1342 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1343 * this.
1344 */
1345 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0)
1346 {
1347 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1348 png_colorspace_sync(png_ptr, info_ptr);
1349 png_chunk_benign_error(png_ptr, "too many profiles");
1350 return;
1351 }
1352
1353 (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
1354 png_colorspace_sync(png_ptr, info_ptr);
1355 }
1356 #endif /* READ_sRGB */
1357
1358 #ifdef PNG_READ_iCCP_SUPPORTED
1359 void /* PRIVATE */
png_handle_iCCP(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1360 png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1361 /* Note: this does not properly handle profiles that are > 64K under DOS */
1362 {
1363 png_const_charp errmsg = NULL; /* error message output, or no error */
1364 int finished = 0; /* crc checked */
1365
1366 png_debug(1, "in png_handle_iCCP");
1367
1368 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1369 png_chunk_error(png_ptr, "missing IHDR");
1370
1371 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1372 {
1373 png_crc_finish(png_ptr, length);
1374 png_chunk_benign_error(png_ptr, "out of place");
1375 return;
1376 }
1377
1378 /* Consistent with all the above colorspace handling an obviously *invalid*
1379 * chunk is just ignored, so does not invalidate the color space. An
1380 * alternative is to set the 'invalid' flags at the start of this routine
1381 * and only clear them in they were not set before and all the tests pass.
1382 */
1383
1384 /* The keyword must be at least one character and there is a
1385 * terminator (0) byte and the compression method byte, and the
1386 * 'zlib' datastream is at least 11 bytes.
1387 */
1388 if (length < 14)
1389 {
1390 png_crc_finish(png_ptr, length);
1391 png_chunk_benign_error(png_ptr, "too short");
1392 return;
1393 }
1394
1395 /* If a colorspace error has already been output skip this chunk */
1396 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1397 {
1398 png_crc_finish(png_ptr, length);
1399 return;
1400 }
1401
1402 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1403 * this.
1404 */
1405 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
1406 {
1407 uInt read_length, keyword_length;
1408 char keyword[81];
1409
1410 /* Find the keyword; the keyword plus separator and compression method
1411 * bytes can be at most 81 characters long.
1412 */
1413 read_length = 81; /* maximum */
1414 if (read_length > length)
1415 read_length = (uInt)length;
1416
1417 png_crc_read(png_ptr, (png_bytep)keyword, read_length);
1418 length -= read_length;
1419
1420 /* The minimum 'zlib' stream is assumed to be just the 2 byte header,
1421 * 5 bytes minimum 'deflate' stream, and the 4 byte checksum.
1422 */
1423 if (length < 11)
1424 {
1425 png_crc_finish(png_ptr, length);
1426 png_chunk_benign_error(png_ptr, "too short");
1427 return;
1428 }
1429
1430 keyword_length = 0;
1431 while (keyword_length < 80 && keyword_length < read_length &&
1432 keyword[keyword_length] != 0)
1433 ++keyword_length;
1434
1435 /* TODO: make the keyword checking common */
1436 if (keyword_length >= 1 && keyword_length <= 79)
1437 {
1438 /* We only understand '0' compression - deflate - so if we get a
1439 * different value we can't safely decode the chunk.
1440 */
1441 if (keyword_length+1 < read_length &&
1442 keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
1443 {
1444 read_length -= keyword_length+2;
1445
1446 if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
1447 {
1448 Byte profile_header[132]={0};
1449 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
1450 png_alloc_size_t size = (sizeof profile_header);
1451
1452 png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
1453 png_ptr->zstream.avail_in = read_length;
1454 (void)png_inflate_read(png_ptr, local_buffer,
1455 (sizeof local_buffer), &length, profile_header, &size,
1456 0/*finish: don't, because the output is too small*/);
1457
1458 if (size == 0)
1459 {
1460 /* We have the ICC profile header; do the basic header checks.
1461 */
1462 png_uint_32 profile_length = png_get_uint_32(profile_header);
1463
1464 if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
1465 keyword, profile_length) != 0)
1466 {
1467 /* The length is apparently ok, so we can check the 132
1468 * byte header.
1469 */
1470 if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
1471 keyword, profile_length, profile_header,
1472 png_ptr->color_type) != 0)
1473 {
1474 /* Now read the tag table; a variable size buffer is
1475 * needed at this point, allocate one for the whole
1476 * profile. The header check has already validated
1477 * that none of this stuff will overflow.
1478 */
1479 png_uint_32 tag_count =
1480 png_get_uint_32(profile_header + 128);
1481 png_bytep profile = png_read_buffer(png_ptr,
1482 profile_length, 2/*silent*/);
1483
1484 if (profile != NULL)
1485 {
1486 memcpy(profile, profile_header,
1487 (sizeof profile_header));
1488
1489 size = 12 * tag_count;
1490
1491 (void)png_inflate_read(png_ptr, local_buffer,
1492 (sizeof local_buffer), &length,
1493 profile + (sizeof profile_header), &size, 0);
1494
1495 /* Still expect a buffer error because we expect
1496 * there to be some tag data!
1497 */
1498 if (size == 0)
1499 {
1500 if (png_icc_check_tag_table(png_ptr,
1501 &png_ptr->colorspace, keyword, profile_length,
1502 profile) != 0)
1503 {
1504 /* The profile has been validated for basic
1505 * security issues, so read the whole thing in.
1506 */
1507 size = profile_length - (sizeof profile_header)
1508 - 12 * tag_count;
1509
1510 (void)png_inflate_read(png_ptr, local_buffer,
1511 (sizeof local_buffer), &length,
1512 profile + (sizeof profile_header) +
1513 12 * tag_count, &size, 1/*finish*/);
1514
1515 if (length > 0 && !(png_ptr->flags &
1516 PNG_FLAG_BENIGN_ERRORS_WARN))
1517 errmsg = "extra compressed data";
1518
1519 /* But otherwise allow extra data: */
1520 else if (size == 0)
1521 {
1522 if (length > 0)
1523 {
1524 /* This can be handled completely, so
1525 * keep going.
1526 */
1527 png_chunk_warning(png_ptr,
1528 "extra compressed data");
1529 }
1530
1531 png_crc_finish(png_ptr, length);
1532 finished = 1;
1533
1534 # if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
1535 /* Check for a match against sRGB */
1536 png_icc_set_sRGB(png_ptr,
1537 &png_ptr->colorspace, profile,
1538 png_ptr->zstream.adler);
1539 # endif
1540
1541 /* Steal the profile for info_ptr. */
1542 if (info_ptr != NULL)
1543 {
1544 png_free_data(png_ptr, info_ptr,
1545 PNG_FREE_ICCP, 0);
1546
1547 info_ptr->iccp_name = png_voidcast(char*,
1548 png_malloc_base(png_ptr,
1549 keyword_length+1));
1550 if (info_ptr->iccp_name != NULL)
1551 {
1552 memcpy(info_ptr->iccp_name, keyword,
1553 keyword_length+1);
1554 info_ptr->iccp_proflen =
1555 profile_length;
1556 info_ptr->iccp_profile = profile;
1557 png_ptr->read_buffer = NULL; /*steal*/
1558 info_ptr->free_me |= PNG_FREE_ICCP;
1559 info_ptr->valid |= PNG_INFO_iCCP;
1560 }
1561
1562 else
1563 {
1564 png_ptr->colorspace.flags |=
1565 PNG_COLORSPACE_INVALID;
1566 errmsg = "out of memory";
1567 }
1568 }
1569
1570 /* else the profile remains in the read
1571 * buffer which gets reused for subsequent
1572 * chunks.
1573 */
1574
1575 if (info_ptr != NULL)
1576 png_colorspace_sync(png_ptr, info_ptr);
1577
1578 if (errmsg == NULL)
1579 {
1580 png_ptr->zowner = 0;
1581 return;
1582 }
1583 }
1584 if (errmsg == NULL)
1585 errmsg = png_ptr->zstream.msg;
1586 }
1587 /* else png_icc_check_tag_table output an error */
1588 }
1589 else /* profile truncated */
1590 errmsg = png_ptr->zstream.msg;
1591 }
1592
1593 else
1594 errmsg = "out of memory";
1595 }
1596
1597 /* else png_icc_check_header output an error */
1598 }
1599
1600 /* else png_icc_check_length output an error */
1601 }
1602
1603 else /* profile truncated */
1604 errmsg = png_ptr->zstream.msg;
1605
1606 /* Release the stream */
1607 png_ptr->zowner = 0;
1608 }
1609
1610 else /* png_inflate_claim failed */
1611 errmsg = png_ptr->zstream.msg;
1612 }
1613
1614 else
1615 errmsg = "bad compression method"; /* or missing */
1616 }
1617
1618 else
1619 errmsg = "bad keyword";
1620 }
1621
1622 else
1623 errmsg = "too many profiles";
1624
1625 /* Failure: the reason is in 'errmsg' */
1626 if (finished == 0)
1627 png_crc_finish(png_ptr, length);
1628
1629 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1630 png_colorspace_sync(png_ptr, info_ptr);
1631 if (errmsg != NULL) /* else already output */
1632 png_chunk_benign_error(png_ptr, errmsg);
1633 }
1634 #endif /* READ_iCCP */
1635
1636 #ifdef PNG_READ_sPLT_SUPPORTED
1637 void /* PRIVATE */
png_handle_sPLT(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1638 png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1639 /* Note: this does not properly handle chunks that are > 64K under DOS */
1640 {
1641 png_bytep entry_start, buffer;
1642 png_sPLT_t new_palette;
1643 png_sPLT_entryp pp;
1644 png_uint_32 data_length;
1645 int entry_size, i;
1646 png_uint_32 skip = 0;
1647 png_uint_32 dl;
1648 size_t max_dl;
1649
1650 png_debug(1, "in png_handle_sPLT");
1651
1652 #ifdef PNG_USER_LIMITS_SUPPORTED
1653 if (png_ptr->user_chunk_cache_max != 0)
1654 {
1655 if (png_ptr->user_chunk_cache_max == 1)
1656 {
1657 png_crc_finish(png_ptr, length);
1658 return;
1659 }
1660
1661 if (--png_ptr->user_chunk_cache_max == 1)
1662 {
1663 png_warning(png_ptr, "No space in chunk cache for sPLT");
1664 png_crc_finish(png_ptr, length);
1665 return;
1666 }
1667 }
1668 #endif
1669
1670 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1671 png_chunk_error(png_ptr, "missing IHDR");
1672
1673 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
1674 {
1675 png_crc_finish(png_ptr, length);
1676 png_chunk_benign_error(png_ptr, "out of place");
1677 return;
1678 }
1679
1680 #ifdef PNG_MAX_MALLOC_64K
1681 if (length > 65535U)
1682 {
1683 png_crc_finish(png_ptr, length);
1684 png_chunk_benign_error(png_ptr, "too large to fit in memory");
1685 return;
1686 }
1687 #endif
1688
1689 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
1690 if (buffer == NULL)
1691 {
1692 png_crc_finish(png_ptr, length);
1693 png_chunk_benign_error(png_ptr, "out of memory");
1694 return;
1695 }
1696
1697
1698 /* WARNING: this may break if size_t is less than 32 bits; it is assumed
1699 * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
1700 * potential breakage point if the types in pngconf.h aren't exactly right.
1701 */
1702 png_crc_read(png_ptr, buffer, length);
1703
1704 if (png_crc_finish(png_ptr, skip) != 0)
1705 return;
1706
1707 buffer[length] = 0;
1708
1709 for (entry_start = buffer; *entry_start; entry_start++)
1710 /* Empty loop to find end of name */ ;
1711
1712 ++entry_start;
1713
1714 /* A sample depth should follow the separator, and we should be on it */
1715 if (length < 2U || entry_start > buffer + (length - 2U))
1716 {
1717 png_warning(png_ptr, "malformed sPLT chunk");
1718 return;
1719 }
1720
1721 new_palette.depth = *entry_start++;
1722 entry_size = (new_palette.depth == 8 ? 6 : 10);
1723 /* This must fit in a png_uint_32 because it is derived from the original
1724 * chunk data length.
1725 */
1726 data_length = length - (png_uint_32)(entry_start - buffer);
1727
1728 /* Integrity-check the data length */
1729 if ((data_length % (unsigned int)entry_size) != 0)
1730 {
1731 png_warning(png_ptr, "sPLT chunk has bad length");
1732 return;
1733 }
1734
1735 dl = (png_uint_32)(data_length / (unsigned int)entry_size);
1736 max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
1737
1738 if (dl > max_dl)
1739 {
1740 png_warning(png_ptr, "sPLT chunk too long");
1741 return;
1742 }
1743
1744 new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size);
1745
1746 new_palette.entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
1747 (png_alloc_size_t) new_palette.nentries * (sizeof (png_sPLT_entry)));
1748
1749 if (new_palette.entries == NULL)
1750 {
1751 png_warning(png_ptr, "sPLT chunk requires too much memory");
1752 return;
1753 }
1754
1755 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1756 for (i = 0; i < new_palette.nentries; i++)
1757 {
1758 pp = new_palette.entries + i;
1759
1760 if (new_palette.depth == 8)
1761 {
1762 pp->red = *entry_start++;
1763 pp->green = *entry_start++;
1764 pp->blue = *entry_start++;
1765 pp->alpha = *entry_start++;
1766 }
1767
1768 else
1769 {
1770 pp->red = png_get_uint_16(entry_start); entry_start += 2;
1771 pp->green = png_get_uint_16(entry_start); entry_start += 2;
1772 pp->blue = png_get_uint_16(entry_start); entry_start += 2;
1773 pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
1774 }
1775
1776 pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
1777 }
1778 #else
1779 pp = new_palette.entries;
1780
1781 for (i = 0; i < new_palette.nentries; i++)
1782 {
1783
1784 if (new_palette.depth == 8)
1785 {
1786 pp[i].red = *entry_start++;
1787 pp[i].green = *entry_start++;
1788 pp[i].blue = *entry_start++;
1789 pp[i].alpha = *entry_start++;
1790 }
1791
1792 else
1793 {
1794 pp[i].red = png_get_uint_16(entry_start); entry_start += 2;
1795 pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
1796 pp[i].blue = png_get_uint_16(entry_start); entry_start += 2;
1797 pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
1798 }
1799
1800 pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
1801 }
1802 #endif
1803
1804 /* Discard all chunk data except the name and stash that */
1805 new_palette.name = (png_charp)buffer;
1806
1807 png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
1808
1809 png_free(png_ptr, new_palette.entries);
1810 }
1811 #endif /* READ_sPLT */
1812
1813 #ifdef PNG_READ_tRNS_SUPPORTED
1814 void /* PRIVATE */
png_handle_tRNS(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1815 png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1816 {
1817 png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
1818
1819 png_debug(1, "in png_handle_tRNS");
1820
1821 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1822 png_chunk_error(png_ptr, "missing IHDR");
1823
1824 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
1825 {
1826 png_crc_finish(png_ptr, length);
1827 png_chunk_benign_error(png_ptr, "out of place");
1828 return;
1829 }
1830
1831 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)
1832 {
1833 png_crc_finish(png_ptr, length);
1834 png_chunk_benign_error(png_ptr, "duplicate");
1835 return;
1836 }
1837
1838 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
1839 {
1840 png_byte buf[2];
1841
1842 if (length != 2)
1843 {
1844 png_crc_finish(png_ptr, length);
1845 png_chunk_benign_error(png_ptr, "invalid");
1846 return;
1847 }
1848
1849 png_crc_read(png_ptr, buf, 2);
1850 png_ptr->num_trans = 1;
1851 png_ptr->trans_color.gray = png_get_uint_16(buf);
1852 }
1853
1854 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
1855 {
1856 png_byte buf[6];
1857
1858 if (length != 6)
1859 {
1860 png_crc_finish(png_ptr, length);
1861 png_chunk_benign_error(png_ptr, "invalid");
1862 return;
1863 }
1864
1865 png_crc_read(png_ptr, buf, length);
1866 png_ptr->num_trans = 1;
1867 png_ptr->trans_color.red = png_get_uint_16(buf);
1868 png_ptr->trans_color.green = png_get_uint_16(buf + 2);
1869 png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
1870 }
1871
1872 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1873 {
1874 if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
1875 {
1876 /* TODO: is this actually an error in the ISO spec? */
1877 png_crc_finish(png_ptr, length);
1878 png_chunk_benign_error(png_ptr, "out of place");
1879 return;
1880 }
1881
1882 if (length > (unsigned int) png_ptr->num_palette ||
1883 length > (unsigned int) PNG_MAX_PALETTE_LENGTH ||
1884 length == 0)
1885 {
1886 png_crc_finish(png_ptr, length);
1887 png_chunk_benign_error(png_ptr, "invalid");
1888 return;
1889 }
1890
1891 png_crc_read(png_ptr, readbuf, length);
1892 png_ptr->num_trans = (png_uint_16)length;
1893 }
1894
1895 else
1896 {
1897 png_crc_finish(png_ptr, length);
1898 png_chunk_benign_error(png_ptr, "invalid with alpha channel");
1899 return;
1900 }
1901
1902 if (png_crc_finish(png_ptr, 0) != 0)
1903 {
1904 png_ptr->num_trans = 0;
1905 return;
1906 }
1907
1908 /* TODO: this is a horrible side effect in the palette case because the
1909 * png_struct ends up with a pointer to the tRNS buffer owned by the
1910 * png_info. Fix this.
1911 */
1912 png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
1913 &(png_ptr->trans_color));
1914 }
1915 #endif
1916
1917 #ifdef PNG_READ_bKGD_SUPPORTED
1918 void /* PRIVATE */
png_handle_bKGD(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1919 png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1920 {
1921 unsigned int truelen;
1922 png_byte buf[6];
1923 png_color_16 background;
1924
1925 png_debug(1, "in png_handle_bKGD");
1926
1927 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1928 png_chunk_error(png_ptr, "missing IHDR");
1929
1930 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
1931 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
1932 (png_ptr->mode & PNG_HAVE_PLTE) == 0))
1933 {
1934 png_crc_finish(png_ptr, length);
1935 png_chunk_benign_error(png_ptr, "out of place");
1936 return;
1937 }
1938
1939 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1940 {
1941 png_crc_finish(png_ptr, length);
1942 png_chunk_benign_error(png_ptr, "duplicate");
1943 return;
1944 }
1945
1946 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1947 truelen = 1;
1948
1949 else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1950 truelen = 6;
1951
1952 else
1953 truelen = 2;
1954
1955 if (length != truelen)
1956 {
1957 png_crc_finish(png_ptr, length);
1958 png_chunk_benign_error(png_ptr, "invalid");
1959 return;
1960 }
1961
1962 png_crc_read(png_ptr, buf, truelen);
1963
1964 if (png_crc_finish(png_ptr, 0) != 0)
1965 return;
1966
1967 /* We convert the index value into RGB components so that we can allow
1968 * arbitrary RGB values for background when we have transparency, and
1969 * so it is easy to determine the RGB values of the background color
1970 * from the info_ptr struct.
1971 */
1972 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1973 {
1974 background.index = buf[0];
1975
1976 if (info_ptr != NULL && info_ptr->num_palette != 0)
1977 {
1978 if (buf[0] >= info_ptr->num_palette)
1979 {
1980 png_chunk_benign_error(png_ptr, "invalid index");
1981 return;
1982 }
1983
1984 background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
1985 background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
1986 background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
1987 }
1988
1989 else
1990 background.red = background.green = background.blue = 0;
1991
1992 background.gray = 0;
1993 }
1994
1995 else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
1996 {
1997 if (png_ptr->bit_depth <= 8)
1998 {
1999 if (buf[0] != 0 || buf[1] >= (unsigned int)(1 << png_ptr->bit_depth))
2000 {
2001 png_chunk_benign_error(png_ptr, "invalid gray level");
2002 return;
2003 }
2004 }
2005
2006 background.index = 0;
2007 background.red =
2008 background.green =
2009 background.blue =
2010 background.gray = png_get_uint_16(buf);
2011 }
2012
2013 else
2014 {
2015 if (png_ptr->bit_depth <= 8)
2016 {
2017 if (buf[0] != 0 || buf[2] != 0 || buf[4] != 0)
2018 {
2019 png_chunk_benign_error(png_ptr, "invalid color");
2020 return;
2021 }
2022 }
2023
2024 background.index = 0;
2025 background.red = png_get_uint_16(buf);
2026 background.green = png_get_uint_16(buf + 2);
2027 background.blue = png_get_uint_16(buf + 4);
2028 background.gray = 0;
2029 }
2030
2031 png_set_bKGD(png_ptr, info_ptr, &background);
2032 }
2033 #endif
2034
2035 #ifdef PNG_READ_eXIf_SUPPORTED
2036 void /* PRIVATE */
png_handle_eXIf(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2037 png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2038 {
2039 unsigned int i;
2040
2041 png_debug(1, "in png_handle_eXIf");
2042
2043 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2044 png_chunk_error(png_ptr, "missing IHDR");
2045
2046 if (length < 2)
2047 {
2048 png_crc_finish(png_ptr, length);
2049 png_chunk_benign_error(png_ptr, "too short");
2050 return;
2051 }
2052
2053 else if (info_ptr == NULL || (info_ptr->valid & PNG_INFO_eXIf) != 0)
2054 {
2055 png_crc_finish(png_ptr, length);
2056 png_chunk_benign_error(png_ptr, "duplicate");
2057 return;
2058 }
2059
2060 info_ptr->free_me |= PNG_FREE_EXIF;
2061
2062 info_ptr->eXIf_buf = png_voidcast(png_bytep,
2063 png_malloc_warn(png_ptr, length));
2064
2065 if (info_ptr->eXIf_buf == NULL)
2066 {
2067 png_crc_finish(png_ptr, length);
2068 png_chunk_benign_error(png_ptr, "out of memory");
2069 return;
2070 }
2071
2072 for (i = 0; i < length; i++)
2073 {
2074 png_byte buf[1];
2075 png_crc_read(png_ptr, buf, 1);
2076 info_ptr->eXIf_buf[i] = buf[0];
2077 if (i == 1)
2078 {
2079 if ((buf[0] != 'M' && buf[0] != 'I') ||
2080 (info_ptr->eXIf_buf[0] != buf[0]))
2081 {
2082 png_crc_finish(png_ptr, length - 2);
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
2091 if (png_crc_finish(png_ptr, 0) == 0)
2092 png_set_eXIf_1(png_ptr, info_ptr, length, info_ptr->eXIf_buf);
2093
2094 png_free(png_ptr, info_ptr->eXIf_buf);
2095 info_ptr->eXIf_buf = NULL;
2096 }
2097 #endif
2098
2099 #ifdef PNG_READ_hIST_SUPPORTED
2100 void /* PRIVATE */
png_handle_hIST(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2101 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2102 {
2103 unsigned int num, i;
2104 png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
2105
2106 png_debug(1, "in png_handle_hIST");
2107
2108 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2109 png_chunk_error(png_ptr, "missing IHDR");
2110
2111 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
2112 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
2113 {
2114 png_crc_finish(png_ptr, length);
2115 png_chunk_benign_error(png_ptr, "out of place");
2116 return;
2117 }
2118
2119 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
2120 {
2121 png_crc_finish(png_ptr, length);
2122 png_chunk_benign_error(png_ptr, "duplicate");
2123 return;
2124 }
2125
2126 num = length / 2 ;
2127
2128 if (length != num * 2 ||
2129 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
2153 void /* PRIVATE */
png_handle_pHYs(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2154 png_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
2199 void /* PRIVATE */
png_handle_oFFs(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2200 png_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) */
2246 void /* PRIVATE */
png_handle_pCAL(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2247 png_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 */
2375 void /* PRIVATE */
png_handle_sCAL(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2376 png_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
2468 void /* PRIVATE */
png_handle_tIME(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2469 png_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 */
2514 void /* PRIVATE */
png_handle_tEXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2515 png_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 */
2595 void /* PRIVATE */
png_handle_zTXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2596 png_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 */
2712 void /* PRIVATE */
png_handle_iTXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2713 png_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 */
2862 static int
png_cache_unknown_chunk(png_structrp png_ptr,png_uint_32 length)2863 png_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 */
2921 void /* PRIVATE */
png_handle_unknown(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length,int keep)2922 png_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
3133 void /* PRIVATE */
png_check_chunk_name(png_const_structrp png_ptr,png_uint_32 chunk_name)3134 png_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
3152 void /* PRIVATE */
png_check_chunk_length(png_const_structrp png_ptr,png_uint_32 length)3153 png_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_benign_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 */
3199 void /* PRIVATE */
png_combine_row(png_const_structrp png_ptr,png_bytep dp,int display)3200 png_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
3683 void /* PRIVATE */
png_do_read_interlace(png_row_infop row_info,png_bytep row,int pass,png_uint_32 transformations)3684 png_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
3930 static void
png_read_filter_row_sub(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3931 png_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
3948 static void
png_read_filter_row_up(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3949 png_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
3964 static void
png_read_filter_row_avg(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3965 png_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
3991 static void
png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3992 png_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
4042 static void
png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)4043 png_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
4093 static void
png_init_filter_functions(png_structrp pp)4094 png_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
4130 void /* PRIVATE */
png_read_filter_row(png_structrp pp,png_row_infop row_info,png_bytep row,png_const_bytep prev_row,int filter)4131 png_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
4148 void /* PRIVATE */
png_read_IDAT_data(png_structrp png_ptr,png_bytep output,png_alloc_size_t avail_out)4149 png_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 sequential reader will
4220 * terminally damage the stream, above, by reading the chunk header of the
4221 * following chunk (it then exits with png_error).
4222 *
4223 * TODO: deal more elegantly with truncated IDAT lists.
4224 */
4225 ret = PNG_INFLATE(png_ptr, Z_NO_FLUSH);
4226
4227 /* Take the unconsumed output back. */
4228 if (output != NULL)
4229 avail_out += png_ptr->zstream.avail_out;
4230
4231 else /* avail_out counts the extra bytes */
4232 avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
4233
4234 png_ptr->zstream.avail_out = 0;
4235
4236 if (ret == Z_STREAM_END)
4237 {
4238 /* Do this for safety; we won't read any more into this row. */
4239 png_ptr->zstream.next_out = NULL;
4240
4241 png_ptr->mode |= PNG_AFTER_IDAT;
4242 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4243
4244 if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
4245 png_chunk_benign_error(png_ptr, "Extra compressed data");
4246 break;
4247 }
4248
4249 if (ret != Z_OK)
4250 {
4251 png_zstream_error(png_ptr, ret);
4252
4253 if (output != NULL)
4254 png_chunk_error(png_ptr, png_ptr->zstream.msg);
4255
4256 else /* checking */
4257 {
4258 png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
4259 return;
4260 }
4261 }
4262 } while (avail_out > 0);
4263
4264 if (avail_out > 0)
4265 {
4266 /* The stream ended before the image; this is the same as too few IDATs so
4267 * should be handled the same way.
4268 */
4269 if (output != NULL)
4270 png_error(png_ptr, "Not enough image data");
4271
4272 else /* the deflate stream contained extra data */
4273 png_chunk_benign_error(png_ptr, "Too much image data");
4274 }
4275 }
4276
4277 void /* PRIVATE */
png_read_finish_IDAT(png_structrp png_ptr)4278 png_read_finish_IDAT(png_structrp png_ptr)
4279 {
4280 /* We don't need any more data and the stream should have ended, however the
4281 * LZ end code may actually not have been processed. In this case we must
4282 * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
4283 * may still remain to be consumed.
4284 */
4285 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
4286 {
4287 /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
4288 * the compressed stream, but the stream may be damaged too, so even after
4289 * this call we may need to terminate the zstream ownership.
4290 */
4291 png_read_IDAT_data(png_ptr, NULL, 0);
4292 png_ptr->zstream.next_out = NULL; /* safety */
4293
4294 /* Now clear everything out for safety; the following may not have been
4295 * done.
4296 */
4297 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
4298 {
4299 png_ptr->mode |= PNG_AFTER_IDAT;
4300 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4301 }
4302 }
4303
4304 /* If the zstream has not been released do it now *and* terminate the reading
4305 * of the final IDAT chunk.
4306 */
4307 if (png_ptr->zowner == png_IDAT)
4308 {
4309 /* Always do this; the pointers otherwise point into the read buffer. */
4310 png_ptr->zstream.next_in = NULL;
4311 png_ptr->zstream.avail_in = 0;
4312
4313 /* Now we no longer own the zstream. */
4314 png_ptr->zowner = 0;
4315
4316 /* The slightly weird semantics of the sequential IDAT reading is that we
4317 * are always in or at the end of an IDAT chunk, so we always need to do a
4318 * crc_finish here. If idat_size is non-zero we also need to read the
4319 * spurious bytes at the end of the chunk now.
4320 */
4321 (void)png_crc_finish(png_ptr, png_ptr->idat_size);
4322 }
4323 }
4324
4325 void /* PRIVATE */
png_read_finish_row(png_structrp png_ptr)4326 png_read_finish_row(png_structrp png_ptr)
4327 {
4328 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4329
4330 /* Start of interlace block */
4331 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4332
4333 /* Offset to next interlace block */
4334 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4335
4336 /* Start of interlace block in the y direction */
4337 static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4338
4339 /* Offset to next interlace block in the y direction */
4340 static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4341
4342 png_debug(1, "in png_read_finish_row");
4343 png_ptr->row_number++;
4344 if (png_ptr->row_number < png_ptr->num_rows)
4345 return;
4346
4347 if (png_ptr->interlaced != 0)
4348 {
4349 png_ptr->row_number = 0;
4350
4351 /* TO DO: don't do this if prev_row isn't needed (requires
4352 * read-ahead of the next row's filter byte.
4353 */
4354 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4355
4356 do
4357 {
4358 png_ptr->pass++;
4359
4360 if (png_ptr->pass >= 7)
4361 break;
4362
4363 png_ptr->iwidth = (png_ptr->width +
4364 png_pass_inc[png_ptr->pass] - 1 -
4365 png_pass_start[png_ptr->pass]) /
4366 png_pass_inc[png_ptr->pass];
4367
4368 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4369 {
4370 png_ptr->num_rows = (png_ptr->height +
4371 png_pass_yinc[png_ptr->pass] - 1 -
4372 png_pass_ystart[png_ptr->pass]) /
4373 png_pass_yinc[png_ptr->pass];
4374 }
4375
4376 else /* if (png_ptr->transformations & PNG_INTERLACE) */
4377 break; /* libpng deinterlacing sees every row */
4378
4379 } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
4380
4381 if (png_ptr->pass < 7)
4382 return;
4383 }
4384
4385 /* Here after at the end of the last row of the last pass. */
4386 png_read_finish_IDAT(png_ptr);
4387 }
4388 #endif /* SEQUENTIAL_READ */
4389
4390 void /* PRIVATE */
png_read_start_row(png_structrp png_ptr)4391 png_read_start_row(png_structrp png_ptr)
4392 {
4393 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4394
4395 /* Start of interlace block */
4396 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4397
4398 /* Offset to next interlace block */
4399 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4400
4401 /* Start of interlace block in the y direction */
4402 static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4403
4404 /* Offset to next interlace block in the y direction */
4405 static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4406
4407 unsigned int max_pixel_depth;
4408 size_t row_bytes;
4409
4410 png_debug(1, "in png_read_start_row");
4411
4412 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
4413 png_init_read_transformations(png_ptr);
4414 #endif
4415 if (png_ptr->interlaced != 0)
4416 {
4417 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4418 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
4419 png_pass_ystart[0]) / png_pass_yinc[0];
4420
4421 else
4422 png_ptr->num_rows = png_ptr->height;
4423
4424 png_ptr->iwidth = (png_ptr->width +
4425 png_pass_inc[png_ptr->pass] - 1 -
4426 png_pass_start[png_ptr->pass]) /
4427 png_pass_inc[png_ptr->pass];
4428 }
4429
4430 else
4431 {
4432 png_ptr->num_rows = png_ptr->height;
4433 png_ptr->iwidth = png_ptr->width;
4434 }
4435
4436 max_pixel_depth = (unsigned int)png_ptr->pixel_depth;
4437
4438 /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of
4439 * calculations to calculate the final pixel depth, then
4440 * png_do_read_transforms actually does the transforms. This means that the
4441 * code which effectively calculates this value is actually repeated in three
4442 * separate places. They must all match. Innocent changes to the order of
4443 * transformations can and will break libpng in a way that causes memory
4444 * overwrites.
4445 *
4446 * TODO: fix this.
4447 */
4448 #ifdef PNG_READ_PACK_SUPPORTED
4449 if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8)
4450 max_pixel_depth = 8;
4451 #endif
4452
4453 #ifdef PNG_READ_EXPAND_SUPPORTED
4454 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4455 {
4456 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4457 {
4458 if (png_ptr->num_trans != 0)
4459 max_pixel_depth = 32;
4460
4461 else
4462 max_pixel_depth = 24;
4463 }
4464
4465 else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4466 {
4467 if (max_pixel_depth < 8)
4468 max_pixel_depth = 8;
4469
4470 if (png_ptr->num_trans != 0)
4471 max_pixel_depth *= 2;
4472 }
4473
4474 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
4475 {
4476 if (png_ptr->num_trans != 0)
4477 {
4478 max_pixel_depth *= 4;
4479 max_pixel_depth /= 3;
4480 }
4481 }
4482 }
4483 #endif
4484
4485 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4486 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4487 {
4488 # ifdef PNG_READ_EXPAND_SUPPORTED
4489 /* In fact it is an error if it isn't supported, but checking is
4490 * the safe way.
4491 */
4492 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4493 {
4494 if (png_ptr->bit_depth < 16)
4495 max_pixel_depth *= 2;
4496 }
4497 else
4498 # endif
4499 png_ptr->transformations &= ~PNG_EXPAND_16;
4500 }
4501 #endif
4502
4503 #ifdef PNG_READ_FILLER_SUPPORTED
4504 if ((png_ptr->transformations & (PNG_FILLER)) != 0)
4505 {
4506 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4507 {
4508 if (max_pixel_depth <= 8)
4509 max_pixel_depth = 16;
4510
4511 else
4512 max_pixel_depth = 32;
4513 }
4514
4515 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
4516 png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4517 {
4518 if (max_pixel_depth <= 32)
4519 max_pixel_depth = 32;
4520
4521 else
4522 max_pixel_depth = 64;
4523 }
4524 }
4525 #endif
4526
4527 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4528 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
4529 {
4530 if (
4531 #ifdef PNG_READ_EXPAND_SUPPORTED
4532 (png_ptr->num_trans != 0 &&
4533 (png_ptr->transformations & PNG_EXPAND) != 0) ||
4534 #endif
4535 #ifdef PNG_READ_FILLER_SUPPORTED
4536 (png_ptr->transformations & (PNG_FILLER)) != 0 ||
4537 #endif
4538 png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4539 {
4540 if (max_pixel_depth <= 16)
4541 max_pixel_depth = 32;
4542
4543 else
4544 max_pixel_depth = 64;
4545 }
4546
4547 else
4548 {
4549 if (max_pixel_depth <= 8)
4550 {
4551 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4552 max_pixel_depth = 32;
4553
4554 else
4555 max_pixel_depth = 24;
4556 }
4557
4558 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4559 max_pixel_depth = 64;
4560
4561 else
4562 max_pixel_depth = 48;
4563 }
4564 }
4565 #endif
4566
4567 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
4568 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
4569 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
4570 {
4571 unsigned int user_pixel_depth = png_ptr->user_transform_depth *
4572 png_ptr->user_transform_channels;
4573
4574 if (user_pixel_depth > max_pixel_depth)
4575 max_pixel_depth = user_pixel_depth;
4576 }
4577 #endif
4578
4579 /* This value is stored in png_struct and double checked in the row read
4580 * code.
4581 */
4582 png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
4583 png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
4584
4585 /* Align the width on the next larger 8 pixels. Mainly used
4586 * for interlacing
4587 */
4588 row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
4589 /* Calculate the maximum bytes needed, adding a byte and a pixel
4590 * for safety's sake
4591 */
4592 row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
4593 1 + ((max_pixel_depth + 7) >> 3U);
4594
4595 #ifdef PNG_MAX_MALLOC_64K
4596 if (row_bytes > (png_uint_32)65536L)
4597 png_error(png_ptr, "This image requires a row greater than 64KB");
4598 #endif
4599
4600 if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
4601 {
4602 png_free(png_ptr, png_ptr->big_row_buf);
4603 png_free(png_ptr, png_ptr->big_prev_row);
4604
4605 if (png_ptr->interlaced != 0)
4606 png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
4607 row_bytes + 48);
4608
4609 else
4610 png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4611
4612 png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4613
4614 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
4615 /* Use 16-byte aligned memory for row_buf with at least 16 bytes
4616 * of padding before and after row_buf; treat prev_row similarly.
4617 * NOTE: the alignment is to the start of the pixels, one beyond the start
4618 * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this
4619 * was incorrect; the filter byte was aligned, which had the exact
4620 * opposite effect of that intended.
4621 */
4622 {
4623 png_bytep temp = png_ptr->big_row_buf + 32;
4624 size_t extra = (size_t)temp & 0x0f;
4625 png_ptr->row_buf = temp - extra - 1/*filter byte*/;
4626
4627 temp = png_ptr->big_prev_row + 32;
4628 extra = (size_t)temp & 0x0f;
4629 png_ptr->prev_row = temp - extra - 1/*filter byte*/;
4630 }
4631 #else
4632 /* Use 31 bytes of padding before and 17 bytes after row_buf. */
4633 png_ptr->row_buf = png_ptr->big_row_buf + 31;
4634 png_ptr->prev_row = png_ptr->big_prev_row + 31;
4635 #endif
4636 png_ptr->old_big_row_buf_size = row_bytes + 48;
4637 }
4638
4639 #ifdef PNG_MAX_MALLOC_64K
4640 if (png_ptr->rowbytes > 65535)
4641 png_error(png_ptr, "This image requires a row greater than 64KB");
4642
4643 #endif
4644 if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
4645 png_error(png_ptr, "Row has too many bytes to allocate in memory");
4646
4647 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4648
4649 png_debug1(3, "width = %u,", png_ptr->width);
4650 png_debug1(3, "height = %u,", png_ptr->height);
4651 png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
4652 png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
4653 png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
4654 png_debug1(3, "irowbytes = %lu",
4655 (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
4656
4657 /* The sequential reader needs a buffer for IDAT, but the progressive reader
4658 * does not, so free the read buffer now regardless; the sequential reader
4659 * reallocates it on demand.
4660 */
4661 if (png_ptr->read_buffer != NULL)
4662 {
4663 png_bytep buffer = png_ptr->read_buffer;
4664
4665 png_ptr->read_buffer_size = 0;
4666 png_ptr->read_buffer = NULL;
4667 png_free(png_ptr, buffer);
4668 }
4669
4670 /* Finally claim the zstream for the inflate of the IDAT data, use the bits
4671 * value from the stream (note that this will result in a fatal error if the
4672 * IDAT stream has a bogus deflate header window_bits value, but this should
4673 * not be happening any longer!)
4674 */
4675 if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
4676 png_error(png_ptr, png_ptr->zstream.msg);
4677
4678 png_ptr->flags |= PNG_FLAG_ROW_INIT;
4679 }
4680 #endif /* READ */
4681