1
2 /* pngrutil.c - utilities to read a PNG file
3 *
4 * Copyright (c) 2018 Cosmin Truta
5 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6 * Copyright (c) 1996-1997 Andreas Dilger
7 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 *
13 * This file contains routines that are only called from within
14 * libpng itself during the course of reading an image.
15 */
16
17 #include "pngpriv.h"
18
19 #ifdef PNG_READ_SUPPORTED
20
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))
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 %lx chunk, length = %lu",
175 (unsigned long)png_ptr->chunk_name, (unsigned long)length);
176
177 /* Reset the crc and run it over the chunk name. */
178 png_reset_crc(png_ptr);
179 png_calculate_crc(png_ptr, buf + 4, 4);
180
181 /* Check to see if chunk name is valid. */
182 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
183
184 /* Check for too-large chunk length */
185 png_check_chunk_length(png_ptr, length);
186
187 #ifdef PNG_IO_STATE_SUPPORTED
188 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
189 #endif
190
191 return length;
192 }
193
194 /* Read data, and (optionally) run it through the CRC. */
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 ((int)(crc != png_ptr->crc));
281 }
282
283 else
284 return (0);
285 }
286
287 #if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
288 defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
289 defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
290 defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
291 /* Manage the read buffer; this simply reallocates the buffer if it is not small
292 * enough (or if it is not allocated). The routine returns a pointer to the
293 * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
294 * it will call png_error (via png_malloc) on failure. (warn == 2 means
295 * 'silent').
296 */
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 = NULL;
306 png_ptr->read_buffer_size = 0;
307 png_free(png_ptr, buffer);
308 buffer = NULL;
309 }
310
311 if (buffer == NULL)
312 {
313 buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
314
315 if (buffer != NULL)
316 {
317 memset(buffer, 0, new_size); /* just in case */
318 png_ptr->read_buffer = buffer;
319 png_ptr->read_buffer_size = new_size;
320 }
321
322 else if (warn < 2) /* else silent */
323 {
324 if (warn != 0)
325 png_chunk_warning(png_ptr, "insufficient memory to read chunk");
326
327 else
328 png_chunk_error(png_ptr, "insufficient memory to read chunk");
329 }
330 }
331
332 return buffer;
333 }
334 #endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
335
336 /* png_inflate_claim: claim the zstream for some nefarious purpose that involves
337 * decompression. Returns Z_OK on success, else a zlib error code. It checks
338 * the owner but, in final release builds, just issues a warning if some other
339 * chunk apparently owns the stream. Prior to release it does a png_error.
340 */
341 static int
png_inflate_claim(png_structrp png_ptr,png_uint_32 owner)342 png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
343 {
344 if (png_ptr->zowner != 0)
345 {
346 char msg[64];
347
348 PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
349 /* So the message that results is "<chunk> using zstream"; this is an
350 * internal error, but is very useful for debugging. i18n requirements
351 * are minimal.
352 */
353 (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
354 #if PNG_RELEASE_BUILD
355 png_chunk_warning(png_ptr, msg);
356 png_ptr->zowner = 0;
357 #else
358 png_chunk_error(png_ptr, msg);
359 #endif
360 }
361
362 /* Implementation note: unlike 'png_deflate_claim' this internal function
363 * does not take the size of the data as an argument. Some efficiency could
364 * be gained by using this when it is known *if* the zlib stream itself does
365 * not record the number; however, this is an illusion: the original writer
366 * of the PNG may have selected a lower window size, and we really must
367 * follow that because, for systems with with limited capabilities, we
368 * would otherwise reject the application's attempts to use a smaller window
369 * size (zlib doesn't have an interface to say "this or lower"!).
370 *
371 * inflateReset2 was added to zlib 1.2.4; before this the window could not be
372 * reset, therefore it is necessary to always allocate the maximum window
373 * size with earlier zlibs just in case later compressed chunks need it.
374 */
375 {
376 int ret; /* zlib return code */
377 #if ZLIB_VERNUM >= 0x1240
378 int window_bits = 0;
379
380 # if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
381 if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
382 PNG_OPTION_ON)
383 {
384 window_bits = 15;
385 png_ptr->zstream_start = 0; /* fixed window size */
386 }
387
388 else
389 {
390 png_ptr->zstream_start = 1;
391 }
392 # endif
393
394 #endif /* ZLIB_VERNUM >= 0x1240 */
395
396 /* Set this for safety, just in case the previous owner left pointers to
397 * memory allocations.
398 */
399 png_ptr->zstream.next_in = NULL;
400 png_ptr->zstream.avail_in = 0;
401 png_ptr->zstream.next_out = NULL;
402 png_ptr->zstream.avail_out = 0;
403
404 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
405 {
406 #if ZLIB_VERNUM >= 0x1240
407 ret = inflateReset2(&png_ptr->zstream, window_bits);
408 #else
409 ret = inflateReset(&png_ptr->zstream);
410 #endif
411 }
412
413 else
414 {
415 #if ZLIB_VERNUM >= 0x1240
416 ret = inflateInit2(&png_ptr->zstream, window_bits);
417 #else
418 ret = inflateInit(&png_ptr->zstream);
419 #endif
420
421 if (ret == Z_OK)
422 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
423 }
424
425 #if ZLIB_VERNUM >= 0x1290 && \
426 defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_IGNORE_ADLER32)
427 if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON)
428 /* Turn off validation of the ADLER32 checksum in IDAT chunks */
429 ret = inflateValidate(&png_ptr->zstream, 0);
430 #endif
431
432 if (ret == Z_OK)
433 png_ptr->zowner = owner;
434
435 else
436 png_zstream_error(png_ptr, ret);
437
438 return ret;
439 }
440
441 #ifdef window_bits
442 # undef window_bits
443 #endif
444 }
445
446 #if ZLIB_VERNUM >= 0x1240
447 /* Handle the start of the inflate stream if we called inflateInit2(strm,0);
448 * in this case some zlib versions skip validation of the CINFO field and, in
449 * certain circumstances, libpng may end up displaying an invalid image, in
450 * contrast to implementations that call zlib in the normal way (e.g. libpng
451 * 1.5).
452 */
453 int /* PRIVATE */
png_zlib_inflate(png_structrp png_ptr,int flush)454 png_zlib_inflate(png_structrp png_ptr, int flush)
455 {
456 if (png_ptr->zstream_start && png_ptr->zstream.avail_in > 0)
457 {
458 if ((*png_ptr->zstream.next_in >> 4) > 7)
459 {
460 png_ptr->zstream.msg = "invalid window size (libpng)";
461 return Z_DATA_ERROR;
462 }
463
464 png_ptr->zstream_start = 0;
465 }
466
467 return inflate(&png_ptr->zstream, flush);
468 }
469 #endif /* Zlib >= 1.2.4 */
470
471 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
472 #if defined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED)
473 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
474 * allow the caller to do multiple calls if required. If the 'finish' flag is
475 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
476 * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
477 * Z_OK or Z_STREAM_END will be returned on success.
478 *
479 * The input and output sizes are updated to the actual amounts of data consumed
480 * or written, not the amount available (as in a z_stream). The data pointers
481 * are not changed, so the next input is (data+input_size) and the next
482 * available output is (output+output_size).
483 */
484 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)485 png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
486 /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
487 /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
488 {
489 if (png_ptr->zowner == owner) /* Else not claimed */
490 {
491 int ret;
492 png_alloc_size_t avail_out = *output_size_ptr;
493 png_uint_32 avail_in = *input_size_ptr;
494
495 /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
496 * can't even necessarily handle 65536 bytes) because the type uInt is
497 * "16 bits or more". Consequently it is necessary to chunk the input to
498 * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
499 * maximum value that can be stored in a uInt.) It is possible to set
500 * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
501 * a performance advantage, because it reduces the amount of data accessed
502 * at each step and that may give the OS more time to page it in.
503 */
504 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
505 /* avail_in and avail_out are set below from 'size' */
506 png_ptr->zstream.avail_in = 0;
507 png_ptr->zstream.avail_out = 0;
508
509 /* Read directly into the output if it is available (this is set to
510 * a local buffer below if output is NULL).
511 */
512 if (output != NULL)
513 png_ptr->zstream.next_out = output;
514
515 do
516 {
517 uInt avail;
518 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
519
520 /* zlib INPUT BUFFER */
521 /* The setting of 'avail_in' used to be outside the loop; by setting it
522 * inside it is possible to chunk the input to zlib and simply rely on
523 * zlib to advance the 'next_in' pointer. This allows arbitrary
524 * amounts of data to be passed through zlib at the unavoidable cost of
525 * requiring a window save (memcpy of up to 32768 output bytes)
526 * every ZLIB_IO_MAX input bytes.
527 */
528 avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
529
530 avail = ZLIB_IO_MAX;
531
532 if (avail_in < avail)
533 avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
534
535 avail_in -= avail;
536 png_ptr->zstream.avail_in = avail;
537
538 /* zlib OUTPUT BUFFER */
539 avail_out += png_ptr->zstream.avail_out; /* not written last time */
540
541 avail = ZLIB_IO_MAX; /* maximum zlib can process */
542
543 if (output == NULL)
544 {
545 /* Reset the output buffer each time round if output is NULL and
546 * make available the full buffer, up to 'remaining_space'
547 */
548 png_ptr->zstream.next_out = local_buffer;
549 if ((sizeof local_buffer) < avail)
550 avail = (sizeof local_buffer);
551 }
552
553 if (avail_out < avail)
554 avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
555
556 png_ptr->zstream.avail_out = avail;
557 avail_out -= avail;
558
559 /* zlib inflate call */
560 /* In fact 'avail_out' may be 0 at this point, that happens at the end
561 * of the read when the final LZ end code was not passed at the end of
562 * the previous chunk of input data. Tell zlib if we have reached the
563 * end of the output buffer.
564 */
565 ret = PNG_INFLATE(png_ptr, avail_out > 0 ? Z_NO_FLUSH :
566 (finish ? Z_FINISH : Z_SYNC_FLUSH));
567 } while (ret == Z_OK);
568
569 /* For safety kill the local buffer pointer now */
570 if (output == NULL)
571 png_ptr->zstream.next_out = NULL;
572
573 /* Claw back the 'size' and 'remaining_space' byte counts. */
574 avail_in += png_ptr->zstream.avail_in;
575 avail_out += png_ptr->zstream.avail_out;
576
577 /* Update the input and output sizes; the updated values are the amount
578 * consumed or written, effectively the inverse of what zlib uses.
579 */
580 if (avail_out > 0)
581 *output_size_ptr -= avail_out;
582
583 if (avail_in > 0)
584 *input_size_ptr -= avail_in;
585
586 /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
587 png_zstream_error(png_ptr, ret);
588 return ret;
589 }
590
591 else
592 {
593 /* This is a bad internal error. The recovery assigns to the zstream msg
594 * pointer, which is not owned by the caller, but this is safe; it's only
595 * used on errors!
596 */
597 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
598 return Z_STREAM_ERROR;
599 }
600 }
601
602 /*
603 * Decompress trailing data in a chunk. The assumption is that read_buffer
604 * points at an allocated area holding the contents of a chunk with a
605 * trailing compressed part. What we get back is an allocated area
606 * holding the original prefix part and an uncompressed version of the
607 * trailing part (the malloc area passed in is freed).
608 */
609 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)610 png_decompress_chunk(png_structrp png_ptr,
611 png_uint_32 chunklength, png_uint_32 prefix_size,
612 png_alloc_size_t *newlength /* must be initialized to the maximum! */,
613 int terminate /*add a '\0' to the end of the uncompressed data*/)
614 {
615 /* TODO: implement different limits for different types of chunk.
616 *
617 * The caller supplies *newlength set to the maximum length of the
618 * uncompressed data, but this routine allocates space for the prefix and
619 * maybe a '\0' terminator too. We have to assume that 'prefix_size' is
620 * limited only by the maximum chunk size.
621 */
622 png_alloc_size_t limit = PNG_SIZE_MAX;
623
624 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
625 if (png_ptr->user_chunk_malloc_max > 0 &&
626 png_ptr->user_chunk_malloc_max < limit)
627 limit = png_ptr->user_chunk_malloc_max;
628 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
629 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
630 limit = PNG_USER_CHUNK_MALLOC_MAX;
631 # endif
632
633 if (limit >= prefix_size + (terminate != 0))
634 {
635 int ret;
636
637 limit -= prefix_size + (terminate != 0);
638
639 if (limit < *newlength)
640 *newlength = limit;
641
642 /* Now try to claim the stream. */
643 ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
644
645 if (ret == Z_OK)
646 {
647 png_uint_32 lzsize = chunklength - prefix_size;
648
649 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
650 /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
651 /* output: */ NULL, newlength);
652
653 if (ret == Z_STREAM_END)
654 {
655 /* Use 'inflateReset' here, not 'inflateReset2' because this
656 * preserves the previously decided window size (otherwise it would
657 * be necessary to store the previous window size.) In practice
658 * this doesn't matter anyway, because png_inflate will call inflate
659 * with Z_FINISH in almost all cases, so the window will not be
660 * maintained.
661 */
662 if (inflateReset(&png_ptr->zstream) == Z_OK)
663 {
664 /* Because of the limit checks above we know that the new,
665 * expanded, size will fit in a size_t (let alone an
666 * png_alloc_size_t). Use png_malloc_base here to avoid an
667 * extra OOM message.
668 */
669 png_alloc_size_t new_size = *newlength;
670 png_alloc_size_t buffer_size = prefix_size + new_size +
671 (terminate != 0);
672 png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
673 buffer_size));
674
675 if (text != NULL)
676 {
677 memset(text, 0, buffer_size);
678
679 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
680 png_ptr->read_buffer + prefix_size, &lzsize,
681 text + prefix_size, newlength);
682
683 if (ret == Z_STREAM_END)
684 {
685 if (new_size == *newlength)
686 {
687 if (terminate != 0)
688 text[prefix_size + *newlength] = 0;
689
690 if (prefix_size > 0)
691 memcpy(text, png_ptr->read_buffer, prefix_size);
692
693 {
694 png_bytep old_ptr = png_ptr->read_buffer;
695
696 png_ptr->read_buffer = text;
697 png_ptr->read_buffer_size = buffer_size;
698 text = old_ptr; /* freed below */
699 }
700 }
701
702 else
703 {
704 /* The size changed on the second read, there can be no
705 * guarantee that anything is correct at this point.
706 * The 'msg' pointer has been set to "unexpected end of
707 * LZ stream", which is fine, but return an error code
708 * that the caller won't accept.
709 */
710 ret = PNG_UNEXPECTED_ZLIB_RETURN;
711 }
712 }
713
714 else if (ret == Z_OK)
715 ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
716
717 /* Free the text pointer (this is the old read_buffer on
718 * success)
719 */
720 png_free(png_ptr, text);
721
722 /* This really is very benign, but it's still an error because
723 * the extra space may otherwise be used as a Trojan Horse.
724 */
725 if (ret == Z_STREAM_END &&
726 chunklength - prefix_size != lzsize)
727 png_chunk_benign_error(png_ptr, "extra compressed data");
728 }
729
730 else
731 {
732 /* Out of memory allocating the buffer */
733 ret = Z_MEM_ERROR;
734 png_zstream_error(png_ptr, Z_MEM_ERROR);
735 }
736 }
737
738 else
739 {
740 /* inflateReset failed, store the error message */
741 png_zstream_error(png_ptr, ret);
742 ret = PNG_UNEXPECTED_ZLIB_RETURN;
743 }
744 }
745
746 else if (ret == Z_OK)
747 ret = PNG_UNEXPECTED_ZLIB_RETURN;
748
749 /* Release the claimed stream */
750 png_ptr->zowner = 0;
751 }
752
753 else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
754 ret = PNG_UNEXPECTED_ZLIB_RETURN;
755
756 return ret;
757 }
758
759 else
760 {
761 /* Application/configuration limits exceeded */
762 png_zstream_error(png_ptr, Z_MEM_ERROR);
763 return Z_MEM_ERROR;
764 }
765 }
766 #endif /* READ_zTXt || READ_iTXt */
767 #endif /* READ_COMPRESSED_TEXT */
768
769 #ifdef PNG_READ_iCCP_SUPPORTED
770 /* Perform a partial read and decompress, producing 'avail_out' bytes and
771 * reading from the current chunk as required.
772 */
773 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)774 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
775 png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
776 int finish)
777 {
778 if (png_ptr->zowner == png_ptr->chunk_name)
779 {
780 int ret;
781
782 /* next_in and avail_in must have been initialized by the caller. */
783 png_ptr->zstream.next_out = next_out;
784 png_ptr->zstream.avail_out = 0; /* set in the loop */
785
786 do
787 {
788 if (png_ptr->zstream.avail_in == 0)
789 {
790 if (read_size > *chunk_bytes)
791 read_size = (uInt)*chunk_bytes;
792 *chunk_bytes -= read_size;
793
794 if (read_size > 0)
795 png_crc_read(png_ptr, read_buffer, read_size);
796
797 png_ptr->zstream.next_in = read_buffer;
798 png_ptr->zstream.avail_in = read_size;
799 }
800
801 if (png_ptr->zstream.avail_out == 0)
802 {
803 uInt avail = ZLIB_IO_MAX;
804 if (avail > *out_size)
805 avail = (uInt)*out_size;
806 *out_size -= avail;
807
808 png_ptr->zstream.avail_out = avail;
809 }
810
811 /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
812 * the available output is produced; this allows reading of truncated
813 * streams.
814 */
815 ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ?
816 Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
817 }
818 while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
819
820 *out_size += png_ptr->zstream.avail_out;
821 png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
822
823 /* Ensure the error message pointer is always set: */
824 png_zstream_error(png_ptr, ret);
825 return ret;
826 }
827
828 else
829 {
830 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
831 return Z_STREAM_ERROR;
832 }
833 }
834 #endif /* READ_iCCP */
835
836 /* Read and check the IDHR chunk */
837
838 void /* PRIVATE */
png_handle_IHDR(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)839 png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
840 {
841 png_byte buf[13];
842 png_uint_32 width, height;
843 int bit_depth, color_type, compression_type, filter_type;
844 int interlace_type;
845
846 png_debug(1, "in png_handle_IHDR");
847
848 if ((png_ptr->mode & PNG_HAVE_IHDR) != 0)
849 png_chunk_error(png_ptr, "out of place");
850
851 /* Check the length */
852 if (length != 13)
853 png_chunk_error(png_ptr, "invalid");
854
855 png_ptr->mode |= PNG_HAVE_IHDR;
856
857 png_crc_read(png_ptr, buf, 13);
858 png_crc_finish(png_ptr, 0);
859
860 width = png_get_uint_31(png_ptr, buf);
861 height = png_get_uint_31(png_ptr, buf + 4);
862 bit_depth = buf[8];
863 color_type = buf[9];
864 compression_type = buf[10];
865 filter_type = buf[11];
866 interlace_type = buf[12];
867
868 #ifdef PNG_READ_APNG_SUPPORTED
869 png_ptr->first_frame_width = width;
870 png_ptr->first_frame_height = height;
871 #endif
872
873 /* Set internal variables */
874 png_ptr->width = width;
875 png_ptr->height = height;
876 png_ptr->bit_depth = (png_byte)bit_depth;
877 png_ptr->interlaced = (png_byte)interlace_type;
878 png_ptr->color_type = (png_byte)color_type;
879 #ifdef PNG_MNG_FEATURES_SUPPORTED
880 png_ptr->filter_type = (png_byte)filter_type;
881 #endif
882 png_ptr->compression_type = (png_byte)compression_type;
883
884 /* Find number of channels */
885 switch (png_ptr->color_type)
886 {
887 default: /* invalid, png_set_IHDR calls png_error */
888 case PNG_COLOR_TYPE_GRAY:
889 case PNG_COLOR_TYPE_PALETTE:
890 png_ptr->channels = 1;
891 break;
892
893 case PNG_COLOR_TYPE_RGB:
894 png_ptr->channels = 3;
895 break;
896
897 case PNG_COLOR_TYPE_GRAY_ALPHA:
898 png_ptr->channels = 2;
899 break;
900
901 case PNG_COLOR_TYPE_RGB_ALPHA:
902 png_ptr->channels = 4;
903 break;
904 }
905
906 /* Set up other useful info */
907 png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels);
908 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
909 png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
910 png_debug1(3, "channels = %d", png_ptr->channels);
911 png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
912 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
913 color_type, interlace_type, compression_type, filter_type);
914 }
915
916 /* Read and check the palette */
917 void /* PRIVATE */
png_handle_PLTE(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)918 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
919 {
920 png_color palette[PNG_MAX_PALETTE_LENGTH];
921 int max_palette_length, num, i;
922 #ifdef PNG_POINTER_INDEXING_SUPPORTED
923 png_colorp pal_ptr;
924 #endif
925
926 png_debug(1, "in png_handle_PLTE");
927
928 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
929 png_chunk_error(png_ptr, "missing IHDR");
930
931 /* Moved to before the 'after IDAT' check below because otherwise duplicate
932 * PLTE chunks are potentially ignored (the spec says there shall not be more
933 * than one PLTE, the error is not treated as benign, so this check trumps
934 * the requirement that PLTE appears before IDAT.)
935 */
936 else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
937 png_chunk_error(png_ptr, "duplicate");
938
939 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
940 {
941 /* This is benign because the non-benign error happened before, when an
942 * IDAT was encountered in a color-mapped image with no PLTE.
943 */
944 png_crc_finish(png_ptr, length);
945 png_chunk_benign_error(png_ptr, "out of place");
946 return;
947 }
948
949 png_ptr->mode |= PNG_HAVE_PLTE;
950
951 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
952 {
953 png_crc_finish(png_ptr, length);
954 png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
955 return;
956 }
957
958 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
959 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
960 {
961 png_crc_finish(png_ptr, length);
962 return;
963 }
964 #endif
965
966 if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
967 {
968 png_crc_finish(png_ptr, length);
969
970 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
971 png_chunk_benign_error(png_ptr, "invalid");
972
973 else
974 png_chunk_error(png_ptr, "invalid");
975
976 return;
977 }
978
979 /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
980 num = (int)length / 3;
981
982 /* If the palette has 256 or fewer entries but is too large for the bit
983 * depth, we don't issue an error, to preserve the behavior of previous
984 * libpng versions. We silently truncate the unused extra palette entries
985 * here.
986 */
987 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
988 max_palette_length = (1 << png_ptr->bit_depth);
989 else
990 max_palette_length = PNG_MAX_PALETTE_LENGTH;
991
992 if (num > max_palette_length)
993 num = max_palette_length;
994
995 #ifdef PNG_POINTER_INDEXING_SUPPORTED
996 for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
997 {
998 png_byte buf[3];
999
1000 png_crc_read(png_ptr, buf, 3);
1001 pal_ptr->red = buf[0];
1002 pal_ptr->green = buf[1];
1003 pal_ptr->blue = buf[2];
1004 }
1005 #else
1006 for (i = 0; i < num; i++)
1007 {
1008 png_byte buf[3];
1009
1010 png_crc_read(png_ptr, buf, 3);
1011 /* Don't depend upon png_color being any order */
1012 palette[i].red = buf[0];
1013 palette[i].green = buf[1];
1014 palette[i].blue = buf[2];
1015 }
1016 #endif
1017
1018 /* If we actually need the PLTE chunk (ie for a paletted image), we do
1019 * whatever the normal CRC configuration tells us. However, if we
1020 * have an RGB image, the PLTE can be considered ancillary, so
1021 * we will act as though it is.
1022 */
1023 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1024 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1025 #endif
1026 {
1027 png_crc_finish(png_ptr, (png_uint_32) (length - (unsigned int)num * 3));
1028 }
1029
1030 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1031 else if (png_crc_error(png_ptr) != 0) /* Only if we have a CRC error */
1032 {
1033 /* If we don't want to use the data from an ancillary chunk,
1034 * we have two options: an error abort, or a warning and we
1035 * ignore the data in this chunk (which should be OK, since
1036 * it's considered ancillary for a RGB or RGBA image).
1037 *
1038 * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
1039 * chunk type to determine whether to check the ancillary or the critical
1040 * flags.
1041 */
1042 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
1043 {
1044 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0)
1045 return;
1046
1047 else
1048 png_chunk_error(png_ptr, "CRC error");
1049 }
1050
1051 /* Otherwise, we (optionally) emit a warning and use the chunk. */
1052 else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
1053 png_chunk_warning(png_ptr, "CRC error");
1054 }
1055 #endif
1056
1057 /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
1058 * own copy of the palette. This has the side effect that when png_start_row
1059 * is called (this happens after any call to png_read_update_info) the
1060 * info_ptr palette gets changed. This is extremely unexpected and
1061 * confusing.
1062 *
1063 * Fix this by not sharing the palette in this way.
1064 */
1065 png_set_PLTE(png_ptr, info_ptr, palette, num);
1066
1067 /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
1068 * IDAT. Prior to 1.6.0 this was not checked; instead the code merely
1069 * checked the apparent validity of a tRNS chunk inserted before PLTE on a
1070 * palette PNG. 1.6.0 attempts to rigorously follow the standard and
1071 * therefore does a benign error if the erroneous condition is detected *and*
1072 * cancels the tRNS if the benign error returns. The alternative is to
1073 * amend the standard since it would be rather hypocritical of the standards
1074 * maintainers to ignore it.
1075 */
1076 #ifdef PNG_READ_tRNS_SUPPORTED
1077 if (png_ptr->num_trans > 0 ||
1078 (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
1079 {
1080 /* Cancel this because otherwise it would be used if the transforms
1081 * require it. Don't cancel the 'valid' flag because this would prevent
1082 * detection of duplicate chunks.
1083 */
1084 png_ptr->num_trans = 0;
1085
1086 if (info_ptr != NULL)
1087 info_ptr->num_trans = 0;
1088
1089 png_chunk_benign_error(png_ptr, "tRNS must be after");
1090 }
1091 #endif
1092
1093 #ifdef PNG_READ_hIST_SUPPORTED
1094 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
1095 png_chunk_benign_error(png_ptr, "hIST must be after");
1096 #endif
1097
1098 #ifdef PNG_READ_bKGD_SUPPORTED
1099 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1100 png_chunk_benign_error(png_ptr, "bKGD must be after");
1101 #endif
1102 }
1103
1104 void /* PRIVATE */
png_handle_IEND(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1105 png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1106 {
1107 png_debug(1, "in png_handle_IEND");
1108
1109 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0 ||
1110 (png_ptr->mode & PNG_HAVE_IDAT) == 0)
1111 png_chunk_error(png_ptr, "out of place");
1112
1113 png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
1114
1115 png_crc_finish(png_ptr, length);
1116
1117 if (length != 0)
1118 png_chunk_benign_error(png_ptr, "invalid");
1119
1120 PNG_UNUSED(info_ptr)
1121 }
1122
1123 #ifdef PNG_READ_gAMA_SUPPORTED
1124 void /* PRIVATE */
png_handle_gAMA(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1125 png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1126 {
1127 png_fixed_point igamma;
1128 png_byte buf[4];
1129
1130 png_debug(1, "in png_handle_gAMA");
1131
1132 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1133 png_chunk_error(png_ptr, "missing IHDR");
1134
1135 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1136 {
1137 png_crc_finish(png_ptr, length);
1138 png_chunk_benign_error(png_ptr, "out of place");
1139 return;
1140 }
1141
1142 if (length != 4)
1143 {
1144 png_crc_finish(png_ptr, length);
1145 png_chunk_benign_error(png_ptr, "invalid");
1146 return;
1147 }
1148
1149 png_crc_read(png_ptr, buf, 4);
1150
1151 if (png_crc_finish(png_ptr, 0) != 0)
1152 return;
1153
1154 igamma = png_get_fixed_point(NULL, buf);
1155
1156 png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
1157 png_colorspace_sync(png_ptr, info_ptr);
1158 }
1159 #endif
1160
1161 #ifdef PNG_READ_sBIT_SUPPORTED
1162 void /* PRIVATE */
png_handle_sBIT(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1163 png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1164 {
1165 unsigned int truelen, i;
1166 png_byte sample_depth;
1167 png_byte buf[4];
1168
1169 png_debug(1, "in png_handle_sBIT");
1170
1171 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1172 png_chunk_error(png_ptr, "missing IHDR");
1173
1174 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1175 {
1176 png_crc_finish(png_ptr, length);
1177 png_chunk_benign_error(png_ptr, "out of place");
1178 return;
1179 }
1180
1181 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT) != 0)
1182 {
1183 png_crc_finish(png_ptr, length);
1184 png_chunk_benign_error(png_ptr, "duplicate");
1185 return;
1186 }
1187
1188 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1189 {
1190 truelen = 3;
1191 sample_depth = 8;
1192 }
1193
1194 else
1195 {
1196 truelen = png_ptr->channels;
1197 sample_depth = png_ptr->bit_depth;
1198 }
1199
1200 if (length != truelen || length > 4)
1201 {
1202 png_chunk_benign_error(png_ptr, "invalid");
1203 png_crc_finish(png_ptr, length);
1204 return;
1205 }
1206
1207 buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
1208 png_crc_read(png_ptr, buf, truelen);
1209
1210 if (png_crc_finish(png_ptr, 0) != 0)
1211 return;
1212
1213 for (i=0; i<truelen; ++i)
1214 {
1215 if (buf[i] == 0 || buf[i] > sample_depth)
1216 {
1217 png_chunk_benign_error(png_ptr, "invalid");
1218 return;
1219 }
1220 }
1221
1222 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1223 {
1224 png_ptr->sig_bit.red = buf[0];
1225 png_ptr->sig_bit.green = buf[1];
1226 png_ptr->sig_bit.blue = buf[2];
1227 png_ptr->sig_bit.alpha = buf[3];
1228 }
1229
1230 else
1231 {
1232 png_ptr->sig_bit.gray = buf[0];
1233 png_ptr->sig_bit.red = buf[0];
1234 png_ptr->sig_bit.green = buf[0];
1235 png_ptr->sig_bit.blue = buf[0];
1236 png_ptr->sig_bit.alpha = buf[1];
1237 }
1238
1239 png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
1240 }
1241 #endif
1242
1243 #ifdef PNG_READ_cHRM_SUPPORTED
1244 void /* PRIVATE */
png_handle_cHRM(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1245 png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1246 {
1247 png_byte buf[32];
1248 png_xy xy;
1249
1250 png_debug(1, "in png_handle_cHRM");
1251
1252 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1253 png_chunk_error(png_ptr, "missing IHDR");
1254
1255 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1256 {
1257 png_crc_finish(png_ptr, length);
1258 png_chunk_benign_error(png_ptr, "out of place");
1259 return;
1260 }
1261
1262 if (length != 32)
1263 {
1264 png_crc_finish(png_ptr, length);
1265 png_chunk_benign_error(png_ptr, "invalid");
1266 return;
1267 }
1268
1269 png_crc_read(png_ptr, buf, 32);
1270
1271 if (png_crc_finish(png_ptr, 0) != 0)
1272 return;
1273
1274 xy.whitex = png_get_fixed_point(NULL, buf);
1275 xy.whitey = png_get_fixed_point(NULL, buf + 4);
1276 xy.redx = png_get_fixed_point(NULL, buf + 8);
1277 xy.redy = png_get_fixed_point(NULL, buf + 12);
1278 xy.greenx = png_get_fixed_point(NULL, buf + 16);
1279 xy.greeny = png_get_fixed_point(NULL, buf + 20);
1280 xy.bluex = png_get_fixed_point(NULL, buf + 24);
1281 xy.bluey = png_get_fixed_point(NULL, buf + 28);
1282
1283 if (xy.whitex == PNG_FIXED_ERROR ||
1284 xy.whitey == PNG_FIXED_ERROR ||
1285 xy.redx == PNG_FIXED_ERROR ||
1286 xy.redy == PNG_FIXED_ERROR ||
1287 xy.greenx == PNG_FIXED_ERROR ||
1288 xy.greeny == PNG_FIXED_ERROR ||
1289 xy.bluex == PNG_FIXED_ERROR ||
1290 xy.bluey == PNG_FIXED_ERROR)
1291 {
1292 png_chunk_benign_error(png_ptr, "invalid values");
1293 return;
1294 }
1295
1296 /* If a colorspace error has already been output skip this chunk */
1297 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1298 return;
1299
1300 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0)
1301 {
1302 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1303 png_colorspace_sync(png_ptr, info_ptr);
1304 png_chunk_benign_error(png_ptr, "duplicate");
1305 return;
1306 }
1307
1308 png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
1309 (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1310 1/*prefer cHRM values*/);
1311 png_colorspace_sync(png_ptr, info_ptr);
1312 }
1313 #endif
1314
1315 #ifdef PNG_READ_sRGB_SUPPORTED
1316 void /* PRIVATE */
png_handle_sRGB(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1317 png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1318 {
1319 png_byte intent;
1320
1321 png_debug(1, "in png_handle_sRGB");
1322
1323 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1324 png_chunk_error(png_ptr, "missing IHDR");
1325
1326 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1327 {
1328 png_crc_finish(png_ptr, length);
1329 png_chunk_benign_error(png_ptr, "out of place");
1330 return;
1331 }
1332
1333 if (length != 1)
1334 {
1335 png_crc_finish(png_ptr, length);
1336 png_chunk_benign_error(png_ptr, "invalid");
1337 return;
1338 }
1339
1340 png_crc_read(png_ptr, &intent, 1);
1341
1342 if (png_crc_finish(png_ptr, 0) != 0)
1343 return;
1344
1345 /* If a colorspace error has already been output skip this chunk */
1346 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1347 return;
1348
1349 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1350 * this.
1351 */
1352 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0)
1353 {
1354 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1355 png_colorspace_sync(png_ptr, info_ptr);
1356 png_chunk_benign_error(png_ptr, "too many profiles");
1357 return;
1358 }
1359
1360 (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
1361 png_colorspace_sync(png_ptr, info_ptr);
1362 }
1363 #endif /* READ_sRGB */
1364
1365 #ifdef PNG_READ_iCCP_SUPPORTED
1366 void /* PRIVATE */
png_handle_iCCP(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1367 png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1368 /* Note: this does not properly handle profiles that are > 64K under DOS */
1369 {
1370 png_const_charp errmsg = NULL; /* error message output, or no error */
1371 int finished = 0; /* crc checked */
1372
1373 png_debug(1, "in png_handle_iCCP");
1374
1375 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1376 png_chunk_error(png_ptr, "missing IHDR");
1377
1378 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1379 {
1380 png_crc_finish(png_ptr, length);
1381 png_chunk_benign_error(png_ptr, "out of place");
1382 return;
1383 }
1384
1385 /* Consistent with all the above colorspace handling an obviously *invalid*
1386 * chunk is just ignored, so does not invalidate the color space. An
1387 * alternative is to set the 'invalid' flags at the start of this routine
1388 * and only clear them in they were not set before and all the tests pass.
1389 */
1390
1391 /* The keyword must be at least one character and there is a
1392 * terminator (0) byte and the compression method byte, and the
1393 * 'zlib' datastream is at least 11 bytes.
1394 */
1395 if (length < 14)
1396 {
1397 png_crc_finish(png_ptr, length);
1398 png_chunk_benign_error(png_ptr, "too short");
1399 return;
1400 }
1401
1402 /* If a colorspace error has already been output skip this chunk */
1403 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1404 {
1405 png_crc_finish(png_ptr, length);
1406 return;
1407 }
1408
1409 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1410 * this.
1411 */
1412 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
1413 {
1414 uInt read_length, keyword_length;
1415 char keyword[81];
1416
1417 /* Find the keyword; the keyword plus separator and compression method
1418 * bytes can be at most 81 characters long.
1419 */
1420 read_length = 81; /* maximum */
1421 if (read_length > length)
1422 read_length = (uInt)length;
1423
1424 png_crc_read(png_ptr, (png_bytep)keyword, read_length);
1425 length -= read_length;
1426
1427 /* The minimum 'zlib' stream is assumed to be just the 2 byte header,
1428 * 5 bytes minimum 'deflate' stream, and the 4 byte checksum.
1429 */
1430 if (length < 11)
1431 {
1432 png_crc_finish(png_ptr, length);
1433 png_chunk_benign_error(png_ptr, "too short");
1434 return;
1435 }
1436
1437 keyword_length = 0;
1438 while (keyword_length < 80 && keyword_length < read_length &&
1439 keyword[keyword_length] != 0)
1440 ++keyword_length;
1441
1442 /* TODO: make the keyword checking common */
1443 if (keyword_length >= 1 && keyword_length <= 79)
1444 {
1445 /* We only understand '0' compression - deflate - so if we get a
1446 * different value we can't safely decode the chunk.
1447 */
1448 if (keyword_length+1 < read_length &&
1449 keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
1450 {
1451 read_length -= keyword_length+2;
1452
1453 if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
1454 {
1455 Byte profile_header[132]={0};
1456 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
1457 png_alloc_size_t size = (sizeof profile_header);
1458
1459 png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
1460 png_ptr->zstream.avail_in = read_length;
1461 (void)png_inflate_read(png_ptr, local_buffer,
1462 (sizeof local_buffer), &length, profile_header, &size,
1463 0/*finish: don't, because the output is too small*/);
1464
1465 if (size == 0)
1466 {
1467 /* We have the ICC profile header; do the basic header checks.
1468 */
1469 png_uint_32 profile_length = png_get_uint_32(profile_header);
1470
1471 if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
1472 keyword, profile_length) != 0)
1473 {
1474 /* The length is apparently ok, so we can check the 132
1475 * byte header.
1476 */
1477 if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
1478 keyword, profile_length, profile_header,
1479 png_ptr->color_type) != 0)
1480 {
1481 /* Now read the tag table; a variable size buffer is
1482 * needed at this point, allocate one for the whole
1483 * profile. The header check has already validated
1484 * that none of this stuff will overflow.
1485 */
1486 png_uint_32 tag_count =
1487 png_get_uint_32(profile_header + 128);
1488 png_bytep profile = png_read_buffer(png_ptr,
1489 profile_length, 2/*silent*/);
1490
1491 if (profile != NULL)
1492 {
1493 memcpy(profile, profile_header,
1494 (sizeof profile_header));
1495
1496 size = 12 * tag_count;
1497
1498 (void)png_inflate_read(png_ptr, local_buffer,
1499 (sizeof local_buffer), &length,
1500 profile + (sizeof profile_header), &size, 0);
1501
1502 /* Still expect a buffer error because we expect
1503 * there to be some tag data!
1504 */
1505 if (size == 0)
1506 {
1507 if (png_icc_check_tag_table(png_ptr,
1508 &png_ptr->colorspace, keyword, profile_length,
1509 profile) != 0)
1510 {
1511 /* The profile has been validated for basic
1512 * security issues, so read the whole thing in.
1513 */
1514 size = profile_length - (sizeof profile_header)
1515 - 12 * tag_count;
1516
1517 (void)png_inflate_read(png_ptr, local_buffer,
1518 (sizeof local_buffer), &length,
1519 profile + (sizeof profile_header) +
1520 12 * tag_count, &size, 1/*finish*/);
1521
1522 if (length > 0 && !(png_ptr->flags &
1523 PNG_FLAG_BENIGN_ERRORS_WARN))
1524 errmsg = "extra compressed data";
1525
1526 /* But otherwise allow extra data: */
1527 else if (size == 0)
1528 {
1529 if (length > 0)
1530 {
1531 /* This can be handled completely, so
1532 * keep going.
1533 */
1534 png_chunk_warning(png_ptr,
1535 "extra compressed data");
1536 }
1537
1538 png_crc_finish(png_ptr, length);
1539 finished = 1;
1540
1541 # if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
1542 /* Check for a match against sRGB */
1543 png_icc_set_sRGB(png_ptr,
1544 &png_ptr->colorspace, profile,
1545 png_ptr->zstream.adler);
1546 # endif
1547
1548 /* Steal the profile for info_ptr. */
1549 if (info_ptr != NULL)
1550 {
1551 png_free_data(png_ptr, info_ptr,
1552 PNG_FREE_ICCP, 0);
1553
1554 info_ptr->iccp_name = png_voidcast(char*,
1555 png_malloc_base(png_ptr,
1556 keyword_length+1));
1557 if (info_ptr->iccp_name != NULL)
1558 {
1559 memcpy(info_ptr->iccp_name, keyword,
1560 keyword_length+1);
1561 info_ptr->iccp_proflen =
1562 profile_length;
1563 info_ptr->iccp_profile = profile;
1564 png_ptr->read_buffer = NULL; /*steal*/
1565 info_ptr->free_me |= PNG_FREE_ICCP;
1566 info_ptr->valid |= PNG_INFO_iCCP;
1567 }
1568
1569 else
1570 {
1571 png_ptr->colorspace.flags |=
1572 PNG_COLORSPACE_INVALID;
1573 errmsg = "out of memory";
1574 }
1575 }
1576
1577 /* else the profile remains in the read
1578 * buffer which gets reused for subsequent
1579 * chunks.
1580 */
1581
1582 if (info_ptr != NULL)
1583 png_colorspace_sync(png_ptr, info_ptr);
1584
1585 if (errmsg == NULL)
1586 {
1587 png_ptr->zowner = 0;
1588 return;
1589 }
1590 }
1591 if (errmsg == NULL)
1592 errmsg = png_ptr->zstream.msg;
1593 }
1594 /* else png_icc_check_tag_table output an error */
1595 }
1596 else /* profile truncated */
1597 errmsg = png_ptr->zstream.msg;
1598 }
1599
1600 else
1601 errmsg = "out of memory";
1602 }
1603
1604 /* else png_icc_check_header output an error */
1605 }
1606
1607 /* else png_icc_check_length output an error */
1608 }
1609
1610 else /* profile truncated */
1611 errmsg = png_ptr->zstream.msg;
1612
1613 /* Release the stream */
1614 png_ptr->zowner = 0;
1615 }
1616
1617 else /* png_inflate_claim failed */
1618 errmsg = png_ptr->zstream.msg;
1619 }
1620
1621 else
1622 errmsg = "bad compression method"; /* or missing */
1623 }
1624
1625 else
1626 errmsg = "bad keyword";
1627 }
1628
1629 else
1630 errmsg = "too many profiles";
1631
1632 /* Failure: the reason is in 'errmsg' */
1633 if (finished == 0)
1634 png_crc_finish(png_ptr, length);
1635
1636 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1637 png_colorspace_sync(png_ptr, info_ptr);
1638 if (errmsg != NULL) /* else already output */
1639 png_chunk_benign_error(png_ptr, errmsg);
1640 }
1641 #endif /* READ_iCCP */
1642
1643 #ifdef PNG_READ_sPLT_SUPPORTED
1644 void /* PRIVATE */
png_handle_sPLT(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1645 png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1646 /* Note: this does not properly handle chunks that are > 64K under DOS */
1647 {
1648 png_bytep entry_start, buffer;
1649 png_sPLT_t new_palette;
1650 png_sPLT_entryp pp;
1651 png_uint_32 data_length;
1652 int entry_size, i;
1653 png_uint_32 skip = 0;
1654 png_uint_32 dl;
1655 size_t max_dl;
1656
1657 png_debug(1, "in png_handle_sPLT");
1658
1659 #ifdef PNG_USER_LIMITS_SUPPORTED
1660 if (png_ptr->user_chunk_cache_max != 0)
1661 {
1662 if (png_ptr->user_chunk_cache_max == 1)
1663 {
1664 png_crc_finish(png_ptr, length);
1665 return;
1666 }
1667
1668 if (--png_ptr->user_chunk_cache_max == 1)
1669 {
1670 png_warning(png_ptr, "No space in chunk cache for sPLT");
1671 png_crc_finish(png_ptr, length);
1672 return;
1673 }
1674 }
1675 #endif
1676
1677 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1678 png_chunk_error(png_ptr, "missing IHDR");
1679
1680 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
1681 {
1682 png_crc_finish(png_ptr, length);
1683 png_chunk_benign_error(png_ptr, "out of place");
1684 return;
1685 }
1686
1687 #ifdef PNG_MAX_MALLOC_64K
1688 if (length > 65535U)
1689 {
1690 png_crc_finish(png_ptr, length);
1691 png_chunk_benign_error(png_ptr, "too large to fit in memory");
1692 return;
1693 }
1694 #endif
1695
1696 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
1697 if (buffer == NULL)
1698 {
1699 png_crc_finish(png_ptr, length);
1700 png_chunk_benign_error(png_ptr, "out of memory");
1701 return;
1702 }
1703
1704
1705 /* WARNING: this may break if size_t is less than 32 bits; it is assumed
1706 * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
1707 * potential breakage point if the types in pngconf.h aren't exactly right.
1708 */
1709 png_crc_read(png_ptr, buffer, length);
1710
1711 if (png_crc_finish(png_ptr, skip) != 0)
1712 return;
1713
1714 buffer[length] = 0;
1715
1716 for (entry_start = buffer; *entry_start; entry_start++)
1717 /* Empty loop to find end of name */ ;
1718
1719 ++entry_start;
1720
1721 /* A sample depth should follow the separator, and we should be on it */
1722 if (length < 2U || entry_start > buffer + (length - 2U))
1723 {
1724 png_warning(png_ptr, "malformed sPLT chunk");
1725 return;
1726 }
1727
1728 new_palette.depth = *entry_start++;
1729 entry_size = (new_palette.depth == 8 ? 6 : 10);
1730 /* This must fit in a png_uint_32 because it is derived from the original
1731 * chunk data length.
1732 */
1733 data_length = length - (png_uint_32)(entry_start - buffer);
1734
1735 /* Integrity-check the data length */
1736 if ((data_length % (unsigned int)entry_size) != 0)
1737 {
1738 png_warning(png_ptr, "sPLT chunk has bad length");
1739 return;
1740 }
1741
1742 dl = (png_uint_32)(data_length / (unsigned int)entry_size);
1743 max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
1744
1745 if (dl > max_dl)
1746 {
1747 png_warning(png_ptr, "sPLT chunk too long");
1748 return;
1749 }
1750
1751 new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size);
1752
1753 new_palette.entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
1754 (png_alloc_size_t) new_palette.nentries * (sizeof (png_sPLT_entry)));
1755
1756 if (new_palette.entries == NULL)
1757 {
1758 png_warning(png_ptr, "sPLT chunk requires too much memory");
1759 return;
1760 }
1761
1762 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1763 for (i = 0; i < new_palette.nentries; i++)
1764 {
1765 pp = new_palette.entries + i;
1766
1767 if (new_palette.depth == 8)
1768 {
1769 pp->red = *entry_start++;
1770 pp->green = *entry_start++;
1771 pp->blue = *entry_start++;
1772 pp->alpha = *entry_start++;
1773 }
1774
1775 else
1776 {
1777 pp->red = png_get_uint_16(entry_start); entry_start += 2;
1778 pp->green = png_get_uint_16(entry_start); entry_start += 2;
1779 pp->blue = png_get_uint_16(entry_start); entry_start += 2;
1780 pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
1781 }
1782
1783 pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
1784 }
1785 #else
1786 pp = new_palette.entries;
1787
1788 for (i = 0; i < new_palette.nentries; i++)
1789 {
1790
1791 if (new_palette.depth == 8)
1792 {
1793 pp[i].red = *entry_start++;
1794 pp[i].green = *entry_start++;
1795 pp[i].blue = *entry_start++;
1796 pp[i].alpha = *entry_start++;
1797 }
1798
1799 else
1800 {
1801 pp[i].red = png_get_uint_16(entry_start); entry_start += 2;
1802 pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
1803 pp[i].blue = png_get_uint_16(entry_start); entry_start += 2;
1804 pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
1805 }
1806
1807 pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
1808 }
1809 #endif
1810
1811 /* Discard all chunk data except the name and stash that */
1812 new_palette.name = (png_charp)buffer;
1813
1814 png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
1815
1816 png_free(png_ptr, new_palette.entries);
1817 }
1818 #endif /* READ_sPLT */
1819
1820 #ifdef PNG_READ_tRNS_SUPPORTED
1821 void /* PRIVATE */
png_handle_tRNS(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1822 png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1823 {
1824 png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
1825
1826 png_debug(1, "in png_handle_tRNS");
1827
1828 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1829 png_chunk_error(png_ptr, "missing IHDR");
1830
1831 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
1832 {
1833 png_crc_finish(png_ptr, length);
1834 png_chunk_benign_error(png_ptr, "out of place");
1835 return;
1836 }
1837
1838 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)
1839 {
1840 png_crc_finish(png_ptr, length);
1841 png_chunk_benign_error(png_ptr, "duplicate");
1842 return;
1843 }
1844
1845 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
1846 {
1847 png_byte buf[2];
1848
1849 if (length != 2)
1850 {
1851 png_crc_finish(png_ptr, length);
1852 png_chunk_benign_error(png_ptr, "invalid");
1853 return;
1854 }
1855
1856 png_crc_read(png_ptr, buf, 2);
1857 png_ptr->num_trans = 1;
1858 png_ptr->trans_color.gray = png_get_uint_16(buf);
1859 }
1860
1861 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
1862 {
1863 png_byte buf[6];
1864
1865 if (length != 6)
1866 {
1867 png_crc_finish(png_ptr, length);
1868 png_chunk_benign_error(png_ptr, "invalid");
1869 return;
1870 }
1871
1872 png_crc_read(png_ptr, buf, length);
1873 png_ptr->num_trans = 1;
1874 png_ptr->trans_color.red = png_get_uint_16(buf);
1875 png_ptr->trans_color.green = png_get_uint_16(buf + 2);
1876 png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
1877 }
1878
1879 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1880 {
1881 if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
1882 {
1883 /* TODO: is this actually an error in the ISO spec? */
1884 png_crc_finish(png_ptr, length);
1885 png_chunk_benign_error(png_ptr, "out of place");
1886 return;
1887 }
1888
1889 if (length > (unsigned int) png_ptr->num_palette ||
1890 length > (unsigned int) PNG_MAX_PALETTE_LENGTH ||
1891 length == 0)
1892 {
1893 png_crc_finish(png_ptr, length);
1894 png_chunk_benign_error(png_ptr, "invalid");
1895 return;
1896 }
1897
1898 png_crc_read(png_ptr, readbuf, length);
1899 png_ptr->num_trans = (png_uint_16)length;
1900 }
1901
1902 else
1903 {
1904 png_crc_finish(png_ptr, length);
1905 png_chunk_benign_error(png_ptr, "invalid with alpha channel");
1906 return;
1907 }
1908
1909 if (png_crc_finish(png_ptr, 0) != 0)
1910 {
1911 png_ptr->num_trans = 0;
1912 return;
1913 }
1914
1915 /* TODO: this is a horrible side effect in the palette case because the
1916 * png_struct ends up with a pointer to the tRNS buffer owned by the
1917 * png_info. Fix this.
1918 */
1919 png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
1920 &(png_ptr->trans_color));
1921 }
1922 #endif
1923
1924 #ifdef PNG_READ_bKGD_SUPPORTED
1925 void /* PRIVATE */
png_handle_bKGD(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1926 png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1927 {
1928 unsigned int truelen;
1929 png_byte buf[6];
1930 png_color_16 background;
1931
1932 png_debug(1, "in png_handle_bKGD");
1933
1934 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1935 png_chunk_error(png_ptr, "missing IHDR");
1936
1937 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
1938 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
1939 (png_ptr->mode & PNG_HAVE_PLTE) == 0))
1940 {
1941 png_crc_finish(png_ptr, length);
1942 png_chunk_benign_error(png_ptr, "out of place");
1943 return;
1944 }
1945
1946 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1947 {
1948 png_crc_finish(png_ptr, length);
1949 png_chunk_benign_error(png_ptr, "duplicate");
1950 return;
1951 }
1952
1953 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1954 truelen = 1;
1955
1956 else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1957 truelen = 6;
1958
1959 else
1960 truelen = 2;
1961
1962 if (length != truelen)
1963 {
1964 png_crc_finish(png_ptr, length);
1965 png_chunk_benign_error(png_ptr, "invalid");
1966 return;
1967 }
1968
1969 png_crc_read(png_ptr, buf, truelen);
1970
1971 if (png_crc_finish(png_ptr, 0) != 0)
1972 return;
1973
1974 /* We convert the index value into RGB components so that we can allow
1975 * arbitrary RGB values for background when we have transparency, and
1976 * so it is easy to determine the RGB values of the background color
1977 * from the info_ptr struct.
1978 */
1979 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1980 {
1981 background.index = buf[0];
1982
1983 if (info_ptr != NULL && info_ptr->num_palette != 0)
1984 {
1985 if (buf[0] >= info_ptr->num_palette)
1986 {
1987 png_chunk_benign_error(png_ptr, "invalid index");
1988 return;
1989 }
1990
1991 background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
1992 background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
1993 background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
1994 }
1995
1996 else
1997 background.red = background.green = background.blue = 0;
1998
1999 background.gray = 0;
2000 }
2001
2002 else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
2003 {
2004 if (png_ptr->bit_depth <= 8)
2005 {
2006 if (buf[0] != 0 || buf[1] >= (unsigned int)(1 << png_ptr->bit_depth))
2007 {
2008 png_chunk_benign_error(png_ptr, "invalid gray level");
2009 return;
2010 }
2011 }
2012
2013 background.index = 0;
2014 background.red =
2015 background.green =
2016 background.blue =
2017 background.gray = png_get_uint_16(buf);
2018 }
2019
2020 else
2021 {
2022 if (png_ptr->bit_depth <= 8)
2023 {
2024 if (buf[0] != 0 || buf[2] != 0 || buf[4] != 0)
2025 {
2026 png_chunk_benign_error(png_ptr, "invalid color");
2027 return;
2028 }
2029 }
2030
2031 background.index = 0;
2032 background.red = png_get_uint_16(buf);
2033 background.green = png_get_uint_16(buf + 2);
2034 background.blue = png_get_uint_16(buf + 4);
2035 background.gray = 0;
2036 }
2037
2038 png_set_bKGD(png_ptr, info_ptr, &background);
2039 }
2040 #endif
2041
2042 #ifdef PNG_READ_eXIf_SUPPORTED
2043 void /* PRIVATE */
png_handle_eXIf(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2044 png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2045 {
2046 unsigned int i;
2047
2048 png_debug(1, "in png_handle_eXIf");
2049
2050 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2051 png_chunk_error(png_ptr, "missing IHDR");
2052
2053 if (length < 2)
2054 {
2055 png_crc_finish(png_ptr, length);
2056 png_chunk_benign_error(png_ptr, "too short");
2057 return;
2058 }
2059
2060 else if (info_ptr == NULL || (info_ptr->valid & PNG_INFO_eXIf) != 0)
2061 {
2062 png_crc_finish(png_ptr, length);
2063 png_chunk_benign_error(png_ptr, "duplicate");
2064 return;
2065 }
2066
2067 info_ptr->free_me |= PNG_FREE_EXIF;
2068
2069 info_ptr->eXIf_buf = png_voidcast(png_bytep,
2070 png_malloc_warn(png_ptr, length));
2071
2072 if (info_ptr->eXIf_buf == NULL)
2073 {
2074 png_crc_finish(png_ptr, length);
2075 png_chunk_benign_error(png_ptr, "out of memory");
2076 return;
2077 }
2078
2079 for (i = 0; i < length; i++)
2080 {
2081 png_byte buf[1];
2082 png_crc_read(png_ptr, buf, 1);
2083 info_ptr->eXIf_buf[i] = buf[0];
2084 if (i == 1 && buf[0] != 'M' && buf[0] != 'I'
2085 && info_ptr->eXIf_buf[0] != buf[0])
2086 {
2087 png_crc_finish(png_ptr, length);
2088 png_chunk_benign_error(png_ptr, "incorrect byte-order specifier");
2089 png_free(png_ptr, info_ptr->eXIf_buf);
2090 info_ptr->eXIf_buf = NULL;
2091 return;
2092 }
2093 }
2094
2095 if (png_crc_finish(png_ptr, 0) != 0)
2096 return;
2097
2098 png_set_eXIf_1(png_ptr, info_ptr, length, info_ptr->eXIf_buf);
2099
2100 png_free(png_ptr, info_ptr->eXIf_buf);
2101 info_ptr->eXIf_buf = NULL;
2102 }
2103 #endif
2104
2105 #ifdef PNG_READ_hIST_SUPPORTED
2106 void /* PRIVATE */
png_handle_hIST(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2107 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2108 {
2109 unsigned int num, i;
2110 png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
2111
2112 png_debug(1, "in png_handle_hIST");
2113
2114 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2115 png_chunk_error(png_ptr, "missing IHDR");
2116
2117 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
2118 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
2119 {
2120 png_crc_finish(png_ptr, length);
2121 png_chunk_benign_error(png_ptr, "out of place");
2122 return;
2123 }
2124
2125 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
2126 {
2127 png_crc_finish(png_ptr, length);
2128 png_chunk_benign_error(png_ptr, "duplicate");
2129 return;
2130 }
2131
2132 num = length / 2 ;
2133
2134 if (num != (unsigned int) png_ptr->num_palette ||
2135 num > (unsigned int) PNG_MAX_PALETTE_LENGTH)
2136 {
2137 png_crc_finish(png_ptr, length);
2138 png_chunk_benign_error(png_ptr, "invalid");
2139 return;
2140 }
2141
2142 for (i = 0; i < num; i++)
2143 {
2144 png_byte buf[2];
2145
2146 png_crc_read(png_ptr, buf, 2);
2147 readbuf[i] = png_get_uint_16(buf);
2148 }
2149
2150 if (png_crc_finish(png_ptr, 0) != 0)
2151 return;
2152
2153 png_set_hIST(png_ptr, info_ptr, readbuf);
2154 }
2155 #endif
2156
2157 #ifdef PNG_READ_pHYs_SUPPORTED
2158 void /* PRIVATE */
png_handle_pHYs(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2159 png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2160 {
2161 png_byte buf[9];
2162 png_uint_32 res_x, res_y;
2163 int unit_type;
2164
2165 png_debug(1, "in png_handle_pHYs");
2166
2167 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2168 png_chunk_error(png_ptr, "missing IHDR");
2169
2170 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2171 {
2172 png_crc_finish(png_ptr, length);
2173 png_chunk_benign_error(png_ptr, "out of place");
2174 return;
2175 }
2176
2177 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs) != 0)
2178 {
2179 png_crc_finish(png_ptr, length);
2180 png_chunk_benign_error(png_ptr, "duplicate");
2181 return;
2182 }
2183
2184 if (length != 9)
2185 {
2186 png_crc_finish(png_ptr, length);
2187 png_chunk_benign_error(png_ptr, "invalid");
2188 return;
2189 }
2190
2191 png_crc_read(png_ptr, buf, 9);
2192
2193 if (png_crc_finish(png_ptr, 0) != 0)
2194 return;
2195
2196 res_x = png_get_uint_32(buf);
2197 res_y = png_get_uint_32(buf + 4);
2198 unit_type = buf[8];
2199 png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
2200 }
2201 #endif
2202
2203 #ifdef PNG_READ_oFFs_SUPPORTED
2204 void /* PRIVATE */
png_handle_oFFs(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2205 png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2206 {
2207 png_byte buf[9];
2208 png_int_32 offset_x, offset_y;
2209 int unit_type;
2210
2211 png_debug(1, "in png_handle_oFFs");
2212
2213 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2214 png_chunk_error(png_ptr, "missing IHDR");
2215
2216 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2217 {
2218 png_crc_finish(png_ptr, length);
2219 png_chunk_benign_error(png_ptr, "out of place");
2220 return;
2221 }
2222
2223 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs) != 0)
2224 {
2225 png_crc_finish(png_ptr, length);
2226 png_chunk_benign_error(png_ptr, "duplicate");
2227 return;
2228 }
2229
2230 if (length != 9)
2231 {
2232 png_crc_finish(png_ptr, length);
2233 png_chunk_benign_error(png_ptr, "invalid");
2234 return;
2235 }
2236
2237 png_crc_read(png_ptr, buf, 9);
2238
2239 if (png_crc_finish(png_ptr, 0) != 0)
2240 return;
2241
2242 offset_x = png_get_int_32(buf);
2243 offset_y = png_get_int_32(buf + 4);
2244 unit_type = buf[8];
2245 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
2246 }
2247 #endif
2248
2249 #ifdef PNG_READ_pCAL_SUPPORTED
2250 /* Read the pCAL chunk (described in the PNG Extensions document) */
2251 void /* PRIVATE */
png_handle_pCAL(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2252 png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2253 {
2254 png_int_32 X0, X1;
2255 png_byte type, nparams;
2256 png_bytep buffer, buf, units, endptr;
2257 png_charpp params;
2258 int i;
2259
2260 png_debug(1, "in png_handle_pCAL");
2261
2262 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2263 png_chunk_error(png_ptr, "missing IHDR");
2264
2265 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2266 {
2267 png_crc_finish(png_ptr, length);
2268 png_chunk_benign_error(png_ptr, "out of place");
2269 return;
2270 }
2271
2272 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL) != 0)
2273 {
2274 png_crc_finish(png_ptr, length);
2275 png_chunk_benign_error(png_ptr, "duplicate");
2276 return;
2277 }
2278
2279 png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
2280 length + 1);
2281
2282 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2283
2284 if (buffer == NULL)
2285 {
2286 png_crc_finish(png_ptr, length);
2287 png_chunk_benign_error(png_ptr, "out of memory");
2288 return;
2289 }
2290
2291 png_crc_read(png_ptr, buffer, length);
2292
2293 if (png_crc_finish(png_ptr, 0) != 0)
2294 return;
2295
2296 buffer[length] = 0; /* Null terminate the last string */
2297
2298 png_debug(3, "Finding end of pCAL purpose string");
2299 for (buf = buffer; *buf; buf++)
2300 /* Empty loop */ ;
2301
2302 endptr = buffer + length;
2303
2304 /* We need to have at least 12 bytes after the purpose string
2305 * in order to get the parameter information.
2306 */
2307 if (endptr - buf <= 12)
2308 {
2309 png_chunk_benign_error(png_ptr, "invalid");
2310 return;
2311 }
2312
2313 png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
2314 X0 = png_get_int_32((png_bytep)buf+1);
2315 X1 = png_get_int_32((png_bytep)buf+5);
2316 type = buf[9];
2317 nparams = buf[10];
2318 units = buf + 11;
2319
2320 png_debug(3, "Checking pCAL equation type and number of parameters");
2321 /* Check that we have the right number of parameters for known
2322 * equation types.
2323 */
2324 if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
2325 (type == PNG_EQUATION_BASE_E && nparams != 3) ||
2326 (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
2327 (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
2328 {
2329 png_chunk_benign_error(png_ptr, "invalid parameter count");
2330 return;
2331 }
2332
2333 else if (type >= PNG_EQUATION_LAST)
2334 {
2335 png_chunk_benign_error(png_ptr, "unrecognized equation type");
2336 }
2337
2338 for (buf = units; *buf; buf++)
2339 /* Empty loop to move past the units string. */ ;
2340
2341 png_debug(3, "Allocating pCAL parameters array");
2342
2343 params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
2344 nparams * (sizeof (png_charp))));
2345
2346 if (params == NULL)
2347 {
2348 png_chunk_benign_error(png_ptr, "out of memory");
2349 return;
2350 }
2351
2352 /* Get pointers to the start of each parameter string. */
2353 for (i = 0; i < nparams; i++)
2354 {
2355 buf++; /* Skip the null string terminator from previous parameter. */
2356
2357 png_debug1(3, "Reading pCAL parameter %d", i);
2358
2359 for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
2360 /* Empty loop to move past each parameter string */ ;
2361
2362 /* Make sure we haven't run out of data yet */
2363 if (buf > endptr)
2364 {
2365 png_free(png_ptr, params);
2366 png_chunk_benign_error(png_ptr, "invalid data");
2367 return;
2368 }
2369 }
2370
2371 png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
2372 (png_charp)units, params);
2373
2374 png_free(png_ptr, params);
2375 }
2376 #endif
2377
2378 #ifdef PNG_READ_sCAL_SUPPORTED
2379 /* Read the sCAL chunk */
2380 void /* PRIVATE */
png_handle_sCAL(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2381 png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2382 {
2383 png_bytep buffer;
2384 size_t i;
2385 int state;
2386
2387 png_debug(1, "in png_handle_sCAL");
2388
2389 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2390 png_chunk_error(png_ptr, "missing IHDR");
2391
2392 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2393 {
2394 png_crc_finish(png_ptr, length);
2395 png_chunk_benign_error(png_ptr, "out of place");
2396 return;
2397 }
2398
2399 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL) != 0)
2400 {
2401 png_crc_finish(png_ptr, length);
2402 png_chunk_benign_error(png_ptr, "duplicate");
2403 return;
2404 }
2405
2406 /* Need unit type, width, \0, height: minimum 4 bytes */
2407 else if (length < 4)
2408 {
2409 png_crc_finish(png_ptr, length);
2410 png_chunk_benign_error(png_ptr, "invalid");
2411 return;
2412 }
2413
2414 png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
2415 length + 1);
2416
2417 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2418
2419 if (buffer == NULL)
2420 {
2421 png_chunk_benign_error(png_ptr, "out of memory");
2422 png_crc_finish(png_ptr, length);
2423 return;
2424 }
2425
2426 png_crc_read(png_ptr, buffer, length);
2427 buffer[length] = 0; /* Null terminate the last string */
2428
2429 if (png_crc_finish(png_ptr, 0) != 0)
2430 return;
2431
2432 /* Validate the unit. */
2433 if (buffer[0] != 1 && buffer[0] != 2)
2434 {
2435 png_chunk_benign_error(png_ptr, "invalid unit");
2436 return;
2437 }
2438
2439 /* Validate the ASCII numbers, need two ASCII numbers separated by
2440 * a '\0' and they need to fit exactly in the chunk data.
2441 */
2442 i = 1;
2443 state = 0;
2444
2445 if (png_check_fp_number((png_const_charp)buffer, length, &state, &i) == 0 ||
2446 i >= length || buffer[i++] != 0)
2447 png_chunk_benign_error(png_ptr, "bad width format");
2448
2449 else if (PNG_FP_IS_POSITIVE(state) == 0)
2450 png_chunk_benign_error(png_ptr, "non-positive width");
2451
2452 else
2453 {
2454 size_t heighti = i;
2455
2456 state = 0;
2457 if (png_check_fp_number((png_const_charp)buffer, length,
2458 &state, &i) == 0 || i != length)
2459 png_chunk_benign_error(png_ptr, "bad height format");
2460
2461 else if (PNG_FP_IS_POSITIVE(state) == 0)
2462 png_chunk_benign_error(png_ptr, "non-positive height");
2463
2464 else
2465 /* This is the (only) success case. */
2466 png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
2467 (png_charp)buffer+1, (png_charp)buffer+heighti);
2468 }
2469 }
2470 #endif
2471
2472 #ifdef PNG_READ_tIME_SUPPORTED
2473 void /* PRIVATE */
png_handle_tIME(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2474 png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2475 {
2476 png_byte buf[7];
2477 png_time mod_time;
2478
2479 png_debug(1, "in png_handle_tIME");
2480
2481 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2482 png_chunk_error(png_ptr, "missing IHDR");
2483
2484 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME) != 0)
2485 {
2486 png_crc_finish(png_ptr, length);
2487 png_chunk_benign_error(png_ptr, "duplicate");
2488 return;
2489 }
2490
2491 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2492 png_ptr->mode |= PNG_AFTER_IDAT;
2493
2494 if (length != 7)
2495 {
2496 png_crc_finish(png_ptr, length);
2497 png_chunk_benign_error(png_ptr, "invalid");
2498 return;
2499 }
2500
2501 png_crc_read(png_ptr, buf, 7);
2502
2503 if (png_crc_finish(png_ptr, 0) != 0)
2504 return;
2505
2506 mod_time.second = buf[6];
2507 mod_time.minute = buf[5];
2508 mod_time.hour = buf[4];
2509 mod_time.day = buf[3];
2510 mod_time.month = buf[2];
2511 mod_time.year = png_get_uint_16(buf);
2512
2513 png_set_tIME(png_ptr, info_ptr, &mod_time);
2514 }
2515 #endif
2516
2517 #ifdef PNG_READ_tEXt_SUPPORTED
2518 /* Note: this does not properly handle chunks that are > 64K under DOS */
2519 void /* PRIVATE */
png_handle_tEXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2520 png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2521 {
2522 png_text text_info;
2523 png_bytep buffer;
2524 png_charp key;
2525 png_charp text;
2526 png_uint_32 skip = 0;
2527
2528 png_debug(1, "in png_handle_tEXt");
2529
2530 #ifdef PNG_USER_LIMITS_SUPPORTED
2531 if (png_ptr->user_chunk_cache_max != 0)
2532 {
2533 if (png_ptr->user_chunk_cache_max == 1)
2534 {
2535 png_crc_finish(png_ptr, length);
2536 return;
2537 }
2538
2539 if (--png_ptr->user_chunk_cache_max == 1)
2540 {
2541 png_crc_finish(png_ptr, length);
2542 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2543 return;
2544 }
2545 }
2546 #endif
2547
2548 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2549 png_chunk_error(png_ptr, "missing IHDR");
2550
2551 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2552 png_ptr->mode |= PNG_AFTER_IDAT;
2553
2554 #ifdef PNG_MAX_MALLOC_64K
2555 if (length > 65535U)
2556 {
2557 png_crc_finish(png_ptr, length);
2558 png_chunk_benign_error(png_ptr, "too large to fit in memory");
2559 return;
2560 }
2561 #endif
2562
2563 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2564
2565 if (buffer == NULL)
2566 {
2567 png_chunk_benign_error(png_ptr, "out of memory");
2568 return;
2569 }
2570
2571 png_crc_read(png_ptr, buffer, length);
2572
2573 if (png_crc_finish(png_ptr, skip) != 0)
2574 return;
2575
2576 key = (png_charp)buffer;
2577 key[length] = 0;
2578
2579 for (text = key; *text; text++)
2580 /* Empty loop to find end of key */ ;
2581
2582 if (text != key + length)
2583 text++;
2584
2585 text_info.compression = PNG_TEXT_COMPRESSION_NONE;
2586 text_info.key = key;
2587 text_info.lang = NULL;
2588 text_info.lang_key = NULL;
2589 text_info.itxt_length = 0;
2590 text_info.text = text;
2591 text_info.text_length = strlen(text);
2592
2593 if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) != 0)
2594 png_warning(png_ptr, "Insufficient memory to process text chunk");
2595 }
2596 #endif
2597
2598 #ifdef PNG_READ_zTXt_SUPPORTED
2599 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2600 void /* PRIVATE */
png_handle_zTXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2601 png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2602 {
2603 png_const_charp errmsg = NULL;
2604 png_bytep buffer;
2605 png_uint_32 keyword_length;
2606
2607 png_debug(1, "in png_handle_zTXt");
2608
2609 #ifdef PNG_USER_LIMITS_SUPPORTED
2610 if (png_ptr->user_chunk_cache_max != 0)
2611 {
2612 if (png_ptr->user_chunk_cache_max == 1)
2613 {
2614 png_crc_finish(png_ptr, length);
2615 return;
2616 }
2617
2618 if (--png_ptr->user_chunk_cache_max == 1)
2619 {
2620 png_crc_finish(png_ptr, length);
2621 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2622 return;
2623 }
2624 }
2625 #endif
2626
2627 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2628 png_chunk_error(png_ptr, "missing IHDR");
2629
2630 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2631 png_ptr->mode |= PNG_AFTER_IDAT;
2632
2633 /* Note, "length" is sufficient here; we won't be adding
2634 * a null terminator later.
2635 */
2636 buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
2637
2638 if (buffer == NULL)
2639 {
2640 png_crc_finish(png_ptr, length);
2641 png_chunk_benign_error(png_ptr, "out of memory");
2642 return;
2643 }
2644
2645 png_crc_read(png_ptr, buffer, length);
2646
2647 if (png_crc_finish(png_ptr, 0) != 0)
2648 return;
2649
2650 /* TODO: also check that the keyword contents match the spec! */
2651 for (keyword_length = 0;
2652 keyword_length < length && buffer[keyword_length] != 0;
2653 ++keyword_length)
2654 /* Empty loop to find end of name */ ;
2655
2656 if (keyword_length > 79 || keyword_length < 1)
2657 errmsg = "bad keyword";
2658
2659 /* zTXt must have some LZ data after the keyword, although it may expand to
2660 * zero bytes; we need a '\0' at the end of the keyword, the compression type
2661 * then the LZ data:
2662 */
2663 else if (keyword_length + 3 > length)
2664 errmsg = "truncated";
2665
2666 else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
2667 errmsg = "unknown compression type";
2668
2669 else
2670 {
2671 png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
2672
2673 /* TODO: at present png_decompress_chunk imposes a single application
2674 * level memory limit, this should be split to different values for iCCP
2675 * and text chunks.
2676 */
2677 if (png_decompress_chunk(png_ptr, length, keyword_length+2,
2678 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2679 {
2680 png_text text;
2681
2682 if (png_ptr->read_buffer == NULL)
2683 errmsg="Read failure in png_handle_zTXt";
2684 else
2685 {
2686 /* It worked; png_ptr->read_buffer now looks like a tEXt chunk
2687 * except for the extra compression type byte and the fact that
2688 * it isn't necessarily '\0' terminated.
2689 */
2690 buffer = png_ptr->read_buffer;
2691 buffer[uncompressed_length+(keyword_length+2)] = 0;
2692
2693 text.compression = PNG_TEXT_COMPRESSION_zTXt;
2694 text.key = (png_charp)buffer;
2695 text.text = (png_charp)(buffer + keyword_length+2);
2696 text.text_length = uncompressed_length;
2697 text.itxt_length = 0;
2698 text.lang = NULL;
2699 text.lang_key = NULL;
2700
2701 if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
2702 errmsg = "insufficient memory";
2703 }
2704 }
2705
2706 else
2707 errmsg = png_ptr->zstream.msg;
2708 }
2709
2710 if (errmsg != NULL)
2711 png_chunk_benign_error(png_ptr, errmsg);
2712 }
2713 #endif
2714
2715 #ifdef PNG_READ_iTXt_SUPPORTED
2716 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2717 void /* PRIVATE */
png_handle_iTXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2718 png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2719 {
2720 png_const_charp errmsg = NULL;
2721 png_bytep buffer;
2722 png_uint_32 prefix_length;
2723
2724 png_debug(1, "in png_handle_iTXt");
2725
2726 #ifdef PNG_USER_LIMITS_SUPPORTED
2727 if (png_ptr->user_chunk_cache_max != 0)
2728 {
2729 if (png_ptr->user_chunk_cache_max == 1)
2730 {
2731 png_crc_finish(png_ptr, length);
2732 return;
2733 }
2734
2735 if (--png_ptr->user_chunk_cache_max == 1)
2736 {
2737 png_crc_finish(png_ptr, length);
2738 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2739 return;
2740 }
2741 }
2742 #endif
2743
2744 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2745 png_chunk_error(png_ptr, "missing IHDR");
2746
2747 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2748 png_ptr->mode |= PNG_AFTER_IDAT;
2749
2750 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2751
2752 if (buffer == NULL)
2753 {
2754 png_crc_finish(png_ptr, length);
2755 png_chunk_benign_error(png_ptr, "out of memory");
2756 return;
2757 }
2758
2759 png_crc_read(png_ptr, buffer, length);
2760
2761 if (png_crc_finish(png_ptr, 0) != 0)
2762 return;
2763
2764 /* First the keyword. */
2765 for (prefix_length=0;
2766 prefix_length < length && buffer[prefix_length] != 0;
2767 ++prefix_length)
2768 /* Empty loop */ ;
2769
2770 /* Perform a basic check on the keyword length here. */
2771 if (prefix_length > 79 || prefix_length < 1)
2772 errmsg = "bad keyword";
2773
2774 /* Expect keyword, compression flag, compression type, language, translated
2775 * keyword (both may be empty but are 0 terminated) then the text, which may
2776 * be empty.
2777 */
2778 else if (prefix_length + 5 > length)
2779 errmsg = "truncated";
2780
2781 else if (buffer[prefix_length+1] == 0 ||
2782 (buffer[prefix_length+1] == 1 &&
2783 buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
2784 {
2785 int compressed = buffer[prefix_length+1] != 0;
2786 png_uint_32 language_offset, translated_keyword_offset;
2787 png_alloc_size_t uncompressed_length = 0;
2788
2789 /* Now the language tag */
2790 prefix_length += 3;
2791 language_offset = prefix_length;
2792
2793 for (; prefix_length < length && buffer[prefix_length] != 0;
2794 ++prefix_length)
2795 /* Empty loop */ ;
2796
2797 /* WARNING: the length may be invalid here, this is checked below. */
2798 translated_keyword_offset = ++prefix_length;
2799
2800 for (; prefix_length < length && buffer[prefix_length] != 0;
2801 ++prefix_length)
2802 /* Empty loop */ ;
2803
2804 /* prefix_length should now be at the trailing '\0' of the translated
2805 * keyword, but it may already be over the end. None of this arithmetic
2806 * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
2807 * systems the available allocation may overflow.
2808 */
2809 ++prefix_length;
2810
2811 if (compressed == 0 && prefix_length <= length)
2812 uncompressed_length = length - prefix_length;
2813
2814 else if (compressed != 0 && prefix_length < length)
2815 {
2816 uncompressed_length = PNG_SIZE_MAX;
2817
2818 /* TODO: at present png_decompress_chunk imposes a single application
2819 * level memory limit, this should be split to different values for
2820 * iCCP and text chunks.
2821 */
2822 if (png_decompress_chunk(png_ptr, length, prefix_length,
2823 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2824 buffer = png_ptr->read_buffer;
2825
2826 else
2827 errmsg = png_ptr->zstream.msg;
2828 }
2829
2830 else
2831 errmsg = "truncated";
2832
2833 if (errmsg == NULL)
2834 {
2835 png_text text;
2836
2837 buffer[uncompressed_length+prefix_length] = 0;
2838
2839 if (compressed == 0)
2840 text.compression = PNG_ITXT_COMPRESSION_NONE;
2841
2842 else
2843 text.compression = PNG_ITXT_COMPRESSION_zTXt;
2844
2845 text.key = (png_charp)buffer;
2846 text.lang = (png_charp)buffer + language_offset;
2847 text.lang_key = (png_charp)buffer + translated_keyword_offset;
2848 text.text = (png_charp)buffer + prefix_length;
2849 text.text_length = 0;
2850 text.itxt_length = uncompressed_length;
2851
2852 if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
2853 errmsg = "insufficient memory";
2854 }
2855 }
2856
2857 else
2858 errmsg = "bad compression info";
2859
2860 if (errmsg != NULL)
2861 png_chunk_benign_error(png_ptr, errmsg);
2862 }
2863 #endif
2864
2865 #ifdef PNG_READ_APNG_SUPPORTED
2866 void /* PRIVATE */
png_handle_acTL(png_structp png_ptr,png_infop info_ptr,png_uint_32 length)2867 png_handle_acTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
2868 {
2869 png_byte data[8];
2870 png_uint_32 num_frames;
2871 png_uint_32 num_plays;
2872 png_uint_32 didSet;
2873
2874 png_debug(1, "in png_handle_acTL");
2875
2876 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2877 {
2878 png_error(png_ptr, "Missing IHDR before acTL");
2879 }
2880 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2881 {
2882 png_warning(png_ptr, "Invalid acTL after IDAT skipped");
2883 png_crc_finish(png_ptr, length);
2884 return;
2885 }
2886 else if ((png_ptr->mode & PNG_HAVE_acTL) != 0)
2887 {
2888 png_warning(png_ptr, "Duplicate acTL skipped");
2889 png_crc_finish(png_ptr, length);
2890 return;
2891 }
2892 else if (length != 8)
2893 {
2894 png_warning(png_ptr, "acTL with invalid length skipped");
2895 png_crc_finish(png_ptr, length);
2896 return;
2897 }
2898
2899 png_crc_read(png_ptr, data, 8);
2900 png_crc_finish(png_ptr, 0);
2901
2902 num_frames = png_get_uint_31(png_ptr, data);
2903 num_plays = png_get_uint_31(png_ptr, data + 4);
2904
2905 /* the set function will do error checking on num_frames */
2906 didSet = png_set_acTL(png_ptr, info_ptr, num_frames, num_plays);
2907 if (didSet != 0)
2908 png_ptr->mode |= PNG_HAVE_acTL;
2909 }
2910
2911 void /* PRIVATE */
png_handle_fcTL(png_structp png_ptr,png_infop info_ptr,png_uint_32 length)2912 png_handle_fcTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
2913 {
2914 png_byte data[22];
2915 png_uint_32 width;
2916 png_uint_32 height;
2917 png_uint_32 x_offset;
2918 png_uint_32 y_offset;
2919 png_uint_16 delay_num;
2920 png_uint_16 delay_den;
2921 png_byte dispose_op;
2922 png_byte blend_op;
2923
2924 png_debug(1, "in png_handle_fcTL");
2925
2926 png_ensure_sequence_number(png_ptr, length);
2927
2928 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2929 {
2930 png_error(png_ptr, "Missing IHDR before fcTL");
2931 }
2932 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2933 {
2934 /* for any frames other then the first this message may be misleading,
2935 * but correct. PNG_HAVE_IDAT is unset before the frame head is read
2936 * i can't think of a better message */
2937 png_warning(png_ptr, "Invalid fcTL after IDAT skipped");
2938 png_crc_finish(png_ptr, length-4);
2939 return;
2940 }
2941 else if ((png_ptr->mode & PNG_HAVE_fcTL) != 0)
2942 {
2943 png_warning(png_ptr, "Duplicate fcTL within one frame skipped");
2944 png_crc_finish(png_ptr, length-4);
2945 return;
2946 }
2947 else if (length != 26)
2948 {
2949 png_warning(png_ptr, "fcTL with invalid length skipped");
2950 png_crc_finish(png_ptr, length-4);
2951 return;
2952 }
2953
2954 png_crc_read(png_ptr, data, 22);
2955 png_crc_finish(png_ptr, 0);
2956
2957 width = png_get_uint_31(png_ptr, data);
2958 height = png_get_uint_31(png_ptr, data + 4);
2959 x_offset = png_get_uint_31(png_ptr, data + 8);
2960 y_offset = png_get_uint_31(png_ptr, data + 12);
2961 delay_num = png_get_uint_16(data + 16);
2962 delay_den = png_get_uint_16(data + 18);
2963 dispose_op = data[20];
2964 blend_op = data[21];
2965
2966 if (png_ptr->num_frames_read == 0 && (x_offset != 0 || y_offset != 0))
2967 {
2968 png_warning(png_ptr, "fcTL for the first frame must have zero offset");
2969 return;
2970 }
2971
2972 if (info_ptr != NULL)
2973 {
2974 if (png_ptr->num_frames_read == 0 &&
2975 (width != info_ptr->width || height != info_ptr->height))
2976 {
2977 png_warning(png_ptr, "size in first frame's fcTL must match "
2978 "the size in IHDR");
2979 return;
2980 }
2981
2982 /* The set function will do more error checking */
2983 png_set_next_frame_fcTL(png_ptr, info_ptr, width, height,
2984 x_offset, y_offset, delay_num, delay_den,
2985 dispose_op, blend_op);
2986
2987 png_read_reinit(png_ptr, info_ptr);
2988
2989 png_ptr->mode |= PNG_HAVE_fcTL;
2990 }
2991 }
2992
2993 void /* PRIVATE */
png_have_info(png_structp png_ptr,png_infop info_ptr)2994 png_have_info(png_structp png_ptr, png_infop info_ptr)
2995 {
2996 if ((info_ptr->valid & PNG_INFO_acTL) != 0 &&
2997 (info_ptr->valid & PNG_INFO_fcTL) == 0)
2998 {
2999 png_ptr->apng_flags |= PNG_FIRST_FRAME_HIDDEN;
3000 info_ptr->num_frames++;
3001 }
3002 }
3003
3004 void /* PRIVATE */
png_handle_fdAT(png_structp png_ptr,png_infop info_ptr,png_uint_32 length)3005 png_handle_fdAT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
3006 {
3007 png_ensure_sequence_number(png_ptr, length);
3008
3009 /* This function is only called from png_read_end(), png_read_info(),
3010 * and png_push_read_chunk() which means that:
3011 * - the user doesn't want to read this frame
3012 * - or this is an out-of-place fdAT
3013 * in either case it is safe to ignore the chunk with a warning */
3014 png_warning(png_ptr, "ignoring fdAT chunk");
3015 png_crc_finish(png_ptr, length - 4);
3016 PNG_UNUSED(info_ptr)
3017 }
3018
3019 void /* PRIVATE */
png_ensure_sequence_number(png_structp png_ptr,png_uint_32 length)3020 png_ensure_sequence_number(png_structp png_ptr, png_uint_32 length)
3021 {
3022 png_byte data[4];
3023 png_uint_32 sequence_number;
3024
3025 if (length < 4)
3026 png_error(png_ptr, "invalid fcTL or fdAT chunk found");
3027
3028 png_crc_read(png_ptr, data, 4);
3029 sequence_number = png_get_uint_31(png_ptr, data);
3030
3031 if (sequence_number != png_ptr->next_seq_num)
3032 png_error(png_ptr, "fcTL or fdAT chunk with out-of-order sequence "
3033 "number found");
3034
3035 png_ptr->next_seq_num++;
3036 }
3037 #endif /* READ_APNG */
3038
3039 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
3040 /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
3041 static int
png_cache_unknown_chunk(png_structrp png_ptr,png_uint_32 length)3042 png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
3043 {
3044 png_alloc_size_t limit = PNG_SIZE_MAX;
3045
3046 if (png_ptr->unknown_chunk.data != NULL)
3047 {
3048 png_free(png_ptr, png_ptr->unknown_chunk.data);
3049 png_ptr->unknown_chunk.data = NULL;
3050 }
3051
3052 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
3053 if (png_ptr->user_chunk_malloc_max > 0 &&
3054 png_ptr->user_chunk_malloc_max < limit)
3055 limit = png_ptr->user_chunk_malloc_max;
3056
3057 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
3058 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
3059 limit = PNG_USER_CHUNK_MALLOC_MAX;
3060 # endif
3061
3062 if (length <= limit)
3063 {
3064 PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
3065 /* The following is safe because of the PNG_SIZE_MAX init above */
3066 png_ptr->unknown_chunk.size = (size_t)length/*SAFE*/;
3067 /* 'mode' is a flag array, only the bottom four bits matter here */
3068 png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
3069
3070 if (length == 0)
3071 png_ptr->unknown_chunk.data = NULL;
3072
3073 else
3074 {
3075 /* Do a 'warn' here - it is handled below. */
3076 png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
3077 png_malloc_warn(png_ptr, length));
3078 }
3079 }
3080
3081 if (png_ptr->unknown_chunk.data == NULL && length > 0)
3082 {
3083 /* This is benign because we clean up correctly */
3084 png_crc_finish(png_ptr, length);
3085 png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
3086 return 0;
3087 }
3088
3089 else
3090 {
3091 if (length > 0)
3092 png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
3093 png_crc_finish(png_ptr, 0);
3094 return 1;
3095 }
3096 }
3097 #endif /* READ_UNKNOWN_CHUNKS */
3098
3099 /* Handle an unknown, or known but disabled, chunk */
3100 void /* PRIVATE */
png_handle_unknown(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length,int keep)3101 png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
3102 png_uint_32 length, int keep)
3103 {
3104 int handled = 0; /* the chunk was handled */
3105
3106 png_debug(1, "in png_handle_unknown");
3107
3108 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
3109 /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
3110 * the bug which meant that setting a non-default behavior for a specific
3111 * chunk would be ignored (the default was always used unless a user
3112 * callback was installed).
3113 *
3114 * 'keep' is the value from the png_chunk_unknown_handling, the setting for
3115 * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
3116 * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
3117 * This is just an optimization to avoid multiple calls to the lookup
3118 * function.
3119 */
3120 # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
3121 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
3122 keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
3123 # endif
3124 # endif
3125
3126 /* One of the following methods will read the chunk or skip it (at least one
3127 * of these is always defined because this is the only way to switch on
3128 * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
3129 */
3130 # ifdef PNG_READ_USER_CHUNKS_SUPPORTED
3131 /* The user callback takes precedence over the chunk keep value, but the
3132 * keep value is still required to validate a save of a critical chunk.
3133 */
3134 if (png_ptr->read_user_chunk_fn != NULL)
3135 {
3136 if (png_cache_unknown_chunk(png_ptr, length) != 0)
3137 {
3138 /* Callback to user unknown chunk handler */
3139 int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
3140 &png_ptr->unknown_chunk);
3141
3142 /* ret is:
3143 * negative: An error occurred; png_chunk_error will be called.
3144 * zero: The chunk was not handled, the chunk will be discarded
3145 * unless png_set_keep_unknown_chunks has been used to set
3146 * a 'keep' behavior for this particular chunk, in which
3147 * case that will be used. A critical chunk will cause an
3148 * error at this point unless it is to be saved.
3149 * positive: The chunk was handled, libpng will ignore/discard it.
3150 */
3151 if (ret < 0)
3152 png_chunk_error(png_ptr, "error in user chunk");
3153
3154 else if (ret == 0)
3155 {
3156 /* If the keep value is 'default' or 'never' override it, but
3157 * still error out on critical chunks unless the keep value is
3158 * 'always' While this is weird it is the behavior in 1.4.12.
3159 * A possible improvement would be to obey the value set for the
3160 * chunk, but this would be an API change that would probably
3161 * damage some applications.
3162 *
3163 * The png_app_warning below catches the case that matters, where
3164 * the application has not set specific save or ignore for this
3165 * chunk or global save or ignore.
3166 */
3167 if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
3168 {
3169 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
3170 if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
3171 {
3172 png_chunk_warning(png_ptr, "Saving unknown chunk:");
3173 png_app_warning(png_ptr,
3174 "forcing save of an unhandled chunk;"
3175 " please call png_set_keep_unknown_chunks");
3176 /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
3177 }
3178 # endif
3179 keep = PNG_HANDLE_CHUNK_IF_SAFE;
3180 }
3181 }
3182
3183 else /* chunk was handled */
3184 {
3185 handled = 1;
3186 /* Critical chunks can be safely discarded at this point. */
3187 keep = PNG_HANDLE_CHUNK_NEVER;
3188 }
3189 }
3190
3191 else
3192 keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
3193 }
3194
3195 else
3196 /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
3197 # endif /* READ_USER_CHUNKS */
3198
3199 # ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
3200 {
3201 /* keep is currently just the per-chunk setting, if there was no
3202 * setting change it to the global default now (not that this may
3203 * still be AS_DEFAULT) then obtain the cache of the chunk if required,
3204 * if not simply skip the chunk.
3205 */
3206 if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
3207 keep = png_ptr->unknown_default;
3208
3209 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
3210 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
3211 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
3212 {
3213 if (png_cache_unknown_chunk(png_ptr, length) == 0)
3214 keep = PNG_HANDLE_CHUNK_NEVER;
3215 }
3216
3217 else
3218 png_crc_finish(png_ptr, length);
3219 }
3220 # else
3221 # ifndef PNG_READ_USER_CHUNKS_SUPPORTED
3222 # error no method to support READ_UNKNOWN_CHUNKS
3223 # endif
3224
3225 {
3226 /* If here there is no read callback pointer set and no support is
3227 * compiled in to just save the unknown chunks, so simply skip this
3228 * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then
3229 * the app has erroneously asked for unknown chunk saving when there
3230 * is no support.
3231 */
3232 if (keep > PNG_HANDLE_CHUNK_NEVER)
3233 png_app_error(png_ptr, "no unknown chunk support available");
3234
3235 png_crc_finish(png_ptr, length);
3236 }
3237 # endif
3238
3239 # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
3240 /* Now store the chunk in the chunk list if appropriate, and if the limits
3241 * permit it.
3242 */
3243 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
3244 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
3245 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
3246 {
3247 # ifdef PNG_USER_LIMITS_SUPPORTED
3248 switch (png_ptr->user_chunk_cache_max)
3249 {
3250 case 2:
3251 png_ptr->user_chunk_cache_max = 1;
3252 png_chunk_benign_error(png_ptr, "no space in chunk cache");
3253 /* FALLTHROUGH */
3254 case 1:
3255 /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
3256 * chunk being skipped, now there will be a hard error below.
3257 */
3258 break;
3259
3260 default: /* not at limit */
3261 --(png_ptr->user_chunk_cache_max);
3262 /* FALLTHROUGH */
3263 case 0: /* no limit */
3264 # endif /* USER_LIMITS */
3265 /* Here when the limit isn't reached or when limits are compiled
3266 * out; store the chunk.
3267 */
3268 png_set_unknown_chunks(png_ptr, info_ptr,
3269 &png_ptr->unknown_chunk, 1);
3270 handled = 1;
3271 # ifdef PNG_USER_LIMITS_SUPPORTED
3272 break;
3273 }
3274 # endif
3275 }
3276 # else /* no store support: the chunk must be handled by the user callback */
3277 PNG_UNUSED(info_ptr)
3278 # endif
3279
3280 /* Regardless of the error handling below the cached data (if any) can be
3281 * freed now. Notice that the data is not freed if there is a png_error, but
3282 * it will be freed by destroy_read_struct.
3283 */
3284 if (png_ptr->unknown_chunk.data != NULL)
3285 png_free(png_ptr, png_ptr->unknown_chunk.data);
3286 png_ptr->unknown_chunk.data = NULL;
3287
3288 #else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
3289 /* There is no support to read an unknown chunk, so just skip it. */
3290 png_crc_finish(png_ptr, length);
3291 PNG_UNUSED(info_ptr)
3292 PNG_UNUSED(keep)
3293 #endif /* !READ_UNKNOWN_CHUNKS */
3294
3295 /* Check for unhandled critical chunks */
3296 if (handled == 0 && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
3297 png_chunk_error(png_ptr, "unhandled critical chunk");
3298 }
3299
3300 /* This function is called to verify that a chunk name is valid.
3301 * This function can't have the "critical chunk check" incorporated
3302 * into it, since in the future we will need to be able to call user
3303 * functions to handle unknown critical chunks after we check that
3304 * the chunk name itself is valid.
3305 */
3306
3307 /* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
3308 *
3309 * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
3310 */
3311
3312 void /* PRIVATE */
png_check_chunk_name(png_const_structrp png_ptr,png_uint_32 chunk_name)3313 png_check_chunk_name(png_const_structrp png_ptr, png_uint_32 chunk_name)
3314 {
3315 int i;
3316 png_uint_32 cn=chunk_name;
3317
3318 png_debug(1, "in png_check_chunk_name");
3319
3320 for (i=1; i<=4; ++i)
3321 {
3322 int c = cn & 0xff;
3323
3324 if (c < 65 || c > 122 || (c > 90 && c < 97))
3325 png_chunk_error(png_ptr, "invalid chunk type");
3326
3327 cn >>= 8;
3328 }
3329 }
3330
3331 void /* PRIVATE */
png_check_chunk_length(png_const_structrp png_ptr,png_uint_32 length)3332 png_check_chunk_length(png_const_structrp png_ptr, png_uint_32 length)
3333 {
3334 png_alloc_size_t limit = PNG_UINT_31_MAX;
3335
3336 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
3337 if (png_ptr->user_chunk_malloc_max > 0 &&
3338 png_ptr->user_chunk_malloc_max < limit)
3339 limit = png_ptr->user_chunk_malloc_max;
3340 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
3341 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
3342 limit = PNG_USER_CHUNK_MALLOC_MAX;
3343 # endif
3344 #ifdef PNG_READ_APNG_SUPPORTED
3345 if (png_ptr->chunk_name == png_IDAT || png_ptr->chunk_name == png_fdAT)
3346 #else
3347 if (png_ptr->chunk_name == png_IDAT)
3348 #endif
3349 {
3350 png_alloc_size_t idat_limit = PNG_UINT_31_MAX;
3351 size_t row_factor =
3352 (size_t)png_ptr->width
3353 * (size_t)png_ptr->channels
3354 * (png_ptr->bit_depth > 8? 2: 1)
3355 + 1
3356 + (png_ptr->interlaced? 6: 0);
3357 if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
3358 idat_limit = PNG_UINT_31_MAX;
3359 else
3360 idat_limit = png_ptr->height * row_factor;
3361 row_factor = row_factor > 32566? 32566 : row_factor;
3362 idat_limit += 6 + 5*(idat_limit/row_factor+1); /* zlib+deflate overhead */
3363 idat_limit=idat_limit < PNG_UINT_31_MAX? idat_limit : PNG_UINT_31_MAX;
3364 limit = limit < idat_limit? idat_limit : limit;
3365 }
3366
3367 if (length > limit)
3368 {
3369 png_debug2(0," length = %lu, limit = %lu",
3370 (unsigned long)length,(unsigned long)limit);
3371 png_chunk_error(png_ptr, "chunk data is too large");
3372 }
3373 }
3374
3375 /* Combines the row recently read in with the existing pixels in the row. This
3376 * routine takes care of alpha and transparency if requested. This routine also
3377 * handles the two methods of progressive display of interlaced images,
3378 * depending on the 'display' value; if 'display' is true then the whole row
3379 * (dp) is filled from the start by replicating the available pixels. If
3380 * 'display' is false only those pixels present in the pass are filled in.
3381 */
3382 void /* PRIVATE */
png_combine_row(png_const_structrp png_ptr,png_bytep dp,int display)3383 png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
3384 {
3385 unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
3386 png_const_bytep sp = png_ptr->row_buf + 1;
3387 png_alloc_size_t row_width = png_ptr->width;
3388 unsigned int pass = png_ptr->pass;
3389 png_bytep end_ptr = 0;
3390 png_byte end_byte = 0;
3391 unsigned int end_mask;
3392
3393 png_debug(1, "in png_combine_row");
3394
3395 /* Added in 1.5.6: it should not be possible to enter this routine until at
3396 * least one row has been read from the PNG data and transformed.
3397 */
3398 if (pixel_depth == 0)
3399 png_error(png_ptr, "internal row logic error");
3400
3401 /* Added in 1.5.4: the pixel depth should match the information returned by
3402 * any call to png_read_update_info at this point. Do not continue if we got
3403 * this wrong.
3404 */
3405 if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
3406 PNG_ROWBYTES(pixel_depth, row_width))
3407 png_error(png_ptr, "internal row size calculation error");
3408
3409 /* Don't expect this to ever happen: */
3410 if (row_width == 0)
3411 png_error(png_ptr, "internal row width error");
3412
3413 /* Preserve the last byte in cases where only part of it will be overwritten,
3414 * the multiply below may overflow, we don't care because ANSI-C guarantees
3415 * we get the low bits.
3416 */
3417 end_mask = (pixel_depth * row_width) & 7;
3418 if (end_mask != 0)
3419 {
3420 /* end_ptr == NULL is a flag to say do nothing */
3421 end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
3422 end_byte = *end_ptr;
3423 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3424 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
3425 /* little-endian byte */
3426 end_mask = (unsigned int)(0xff << end_mask);
3427
3428 else /* big-endian byte */
3429 # endif
3430 end_mask = 0xff >> end_mask;
3431 /* end_mask is now the bits to *keep* from the destination row */
3432 }
3433
3434 /* For non-interlaced images this reduces to a memcpy(). A memcpy()
3435 * will also happen if interlacing isn't supported or if the application
3436 * does not call png_set_interlace_handling(). In the latter cases the
3437 * caller just gets a sequence of the unexpanded rows from each interlace
3438 * pass.
3439 */
3440 #ifdef PNG_READ_INTERLACING_SUPPORTED
3441 if (png_ptr->interlaced != 0 &&
3442 (png_ptr->transformations & PNG_INTERLACE) != 0 &&
3443 pass < 6 && (display == 0 ||
3444 /* The following copies everything for 'display' on passes 0, 2 and 4. */
3445 (display == 1 && (pass & 1) != 0)))
3446 {
3447 /* Narrow images may have no bits in a pass; the caller should handle
3448 * this, but this test is cheap:
3449 */
3450 if (row_width <= PNG_PASS_START_COL(pass))
3451 return;
3452
3453 if (pixel_depth < 8)
3454 {
3455 /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
3456 * into 32 bits, then a single loop over the bytes using the four byte
3457 * values in the 32-bit mask can be used. For the 'display' option the
3458 * expanded mask may also not require any masking within a byte. To
3459 * make this work the PACKSWAP option must be taken into account - it
3460 * simply requires the pixels to be reversed in each byte.
3461 *
3462 * The 'regular' case requires a mask for each of the first 6 passes,
3463 * the 'display' case does a copy for the even passes in the range
3464 * 0..6. This has already been handled in the test above.
3465 *
3466 * The masks are arranged as four bytes with the first byte to use in
3467 * the lowest bits (little-endian) regardless of the order (PACKSWAP or
3468 * not) of the pixels in each byte.
3469 *
3470 * NOTE: the whole of this logic depends on the caller of this function
3471 * only calling it on rows appropriate to the pass. This function only
3472 * understands the 'x' logic; the 'y' logic is handled by the caller.
3473 *
3474 * The following defines allow generation of compile time constant bit
3475 * masks for each pixel depth and each possibility of swapped or not
3476 * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index,
3477 * is in the range 0..7; and the result is 1 if the pixel is to be
3478 * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B'
3479 * for the block method.
3480 *
3481 * With some compilers a compile time expression of the general form:
3482 *
3483 * (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
3484 *
3485 * Produces warnings with values of 'shift' in the range 33 to 63
3486 * because the right hand side of the ?: expression is evaluated by
3487 * the compiler even though it isn't used. Microsoft Visual C (various
3488 * versions) and the Intel C compiler are known to do this. To avoid
3489 * this the following macros are used in 1.5.6. This is a temporary
3490 * solution to avoid destabilizing the code during the release process.
3491 */
3492 # if PNG_USE_COMPILE_TIME_MASKS
3493 # define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
3494 # define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
3495 # else
3496 # define PNG_LSR(x,s) ((x)>>(s))
3497 # define PNG_LSL(x,s) ((x)<<(s))
3498 # endif
3499 # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
3500 PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
3501 # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
3502 PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
3503
3504 /* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is
3505 * little endian - the first pixel is at bit 0 - however the extra
3506 * parameter 's' can be set to cause the mask position to be swapped
3507 * within each byte, to match the PNG format. This is done by XOR of
3508 * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
3509 */
3510 # define PIXEL_MASK(p,x,d,s) \
3511 (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
3512
3513 /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
3514 */
3515 # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3516 # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3517
3518 /* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp
3519 * cases the result needs replicating, for the 4-bpp case the above
3520 * generates a full 32 bits.
3521 */
3522 # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
3523
3524 # define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
3525 S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
3526 S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
3527
3528 # define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
3529 B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
3530 B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
3531
3532 #if PNG_USE_COMPILE_TIME_MASKS
3533 /* Utility macros to construct all the masks for a depth/swap
3534 * combination. The 's' parameter says whether the format is PNG
3535 * (big endian bytes) or not. Only the three odd-numbered passes are
3536 * required for the display/block algorithm.
3537 */
3538 # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
3539 S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
3540
3541 # define B_MASKS(d,s) { B_MASK(1,d,s), B_MASK(3,d,s), B_MASK(5,d,s) }
3542
3543 # define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
3544
3545 /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
3546 * then pass:
3547 */
3548 static const png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
3549 {
3550 /* Little-endian byte masks for PACKSWAP */
3551 { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
3552 /* Normal (big-endian byte) masks - PNG format */
3553 { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
3554 };
3555
3556 /* display_mask has only three entries for the odd passes, so index by
3557 * pass>>1.
3558 */
3559 static const png_uint_32 display_mask[2][3][3] =
3560 {
3561 /* Little-endian byte masks for PACKSWAP */
3562 { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
3563 /* Normal (big-endian byte) masks - PNG format */
3564 { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
3565 };
3566
3567 # define MASK(pass,depth,display,png)\
3568 ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
3569 row_mask[png][DEPTH_INDEX(depth)][pass])
3570
3571 #else /* !PNG_USE_COMPILE_TIME_MASKS */
3572 /* This is the runtime alternative: it seems unlikely that this will
3573 * ever be either smaller or faster than the compile time approach.
3574 */
3575 # define MASK(pass,depth,display,png)\
3576 ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
3577 #endif /* !USE_COMPILE_TIME_MASKS */
3578
3579 /* Use the appropriate mask to copy the required bits. In some cases
3580 * the byte mask will be 0 or 0xff; optimize these cases. row_width is
3581 * the number of pixels, but the code copies bytes, so it is necessary
3582 * to special case the end.
3583 */
3584 png_uint_32 pixels_per_byte = 8 / pixel_depth;
3585 png_uint_32 mask;
3586
3587 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3588 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
3589 mask = MASK(pass, pixel_depth, display, 0);
3590
3591 else
3592 # endif
3593 mask = MASK(pass, pixel_depth, display, 1);
3594
3595 for (;;)
3596 {
3597 png_uint_32 m;
3598
3599 /* It doesn't matter in the following if png_uint_32 has more than
3600 * 32 bits because the high bits always match those in m<<24; it is,
3601 * however, essential to use OR here, not +, because of this.
3602 */
3603 m = mask;
3604 mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
3605 m &= 0xff;
3606
3607 if (m != 0) /* something to copy */
3608 {
3609 if (m != 0xff)
3610 *dp = (png_byte)((*dp & ~m) | (*sp & m));
3611 else
3612 *dp = *sp;
3613 }
3614
3615 /* NOTE: this may overwrite the last byte with garbage if the image
3616 * is not an exact number of bytes wide; libpng has always done
3617 * this.
3618 */
3619 if (row_width <= pixels_per_byte)
3620 break; /* May need to restore part of the last byte */
3621
3622 row_width -= pixels_per_byte;
3623 ++dp;
3624 ++sp;
3625 }
3626 }
3627
3628 else /* pixel_depth >= 8 */
3629 {
3630 unsigned int bytes_to_copy, bytes_to_jump;
3631
3632 /* Validate the depth - it must be a multiple of 8 */
3633 if (pixel_depth & 7)
3634 png_error(png_ptr, "invalid user transform pixel depth");
3635
3636 pixel_depth >>= 3; /* now in bytes */
3637 row_width *= pixel_depth;
3638
3639 /* Regardless of pass number the Adam 7 interlace always results in a
3640 * fixed number of pixels to copy then to skip. There may be a
3641 * different number of pixels to skip at the start though.
3642 */
3643 {
3644 unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
3645
3646 row_width -= offset;
3647 dp += offset;
3648 sp += offset;
3649 }
3650
3651 /* Work out the bytes to copy. */
3652 if (display != 0)
3653 {
3654 /* When doing the 'block' algorithm the pixel in the pass gets
3655 * replicated to adjacent pixels. This is why the even (0,2,4,6)
3656 * passes are skipped above - the entire expanded row is copied.
3657 */
3658 bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
3659
3660 /* But don't allow this number to exceed the actual row width. */
3661 if (bytes_to_copy > row_width)
3662 bytes_to_copy = (unsigned int)/*SAFE*/row_width;
3663 }
3664
3665 else /* normal row; Adam7 only ever gives us one pixel to copy. */
3666 bytes_to_copy = pixel_depth;
3667
3668 /* In Adam7 there is a constant offset between where the pixels go. */
3669 bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
3670
3671 /* And simply copy these bytes. Some optimization is possible here,
3672 * depending on the value of 'bytes_to_copy'. Special case the low
3673 * byte counts, which we know to be frequent.
3674 *
3675 * Notice that these cases all 'return' rather than 'break' - this
3676 * avoids an unnecessary test on whether to restore the last byte
3677 * below.
3678 */
3679 switch (bytes_to_copy)
3680 {
3681 case 1:
3682 for (;;)
3683 {
3684 *dp = *sp;
3685
3686 if (row_width <= bytes_to_jump)
3687 return;
3688
3689 dp += bytes_to_jump;
3690 sp += bytes_to_jump;
3691 row_width -= bytes_to_jump;
3692 }
3693
3694 case 2:
3695 /* There is a possibility of a partial copy at the end here; this
3696 * slows the code down somewhat.
3697 */
3698 do
3699 {
3700 dp[0] = sp[0]; dp[1] = sp[1];
3701
3702 if (row_width <= bytes_to_jump)
3703 return;
3704
3705 sp += bytes_to_jump;
3706 dp += bytes_to_jump;
3707 row_width -= bytes_to_jump;
3708 }
3709 while (row_width > 1);
3710
3711 /* And there can only be one byte left at this point: */
3712 *dp = *sp;
3713 return;
3714
3715 case 3:
3716 /* This can only be the RGB case, so each copy is exactly one
3717 * pixel and it is not necessary to check for a partial copy.
3718 */
3719 for (;;)
3720 {
3721 dp[0] = sp[0]; dp[1] = sp[1]; dp[2] = sp[2];
3722
3723 if (row_width <= bytes_to_jump)
3724 return;
3725
3726 sp += bytes_to_jump;
3727 dp += bytes_to_jump;
3728 row_width -= bytes_to_jump;
3729 }
3730
3731 default:
3732 #if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
3733 /* Check for double byte alignment and, if possible, use a
3734 * 16-bit copy. Don't attempt this for narrow images - ones that
3735 * are less than an interlace panel wide. Don't attempt it for
3736 * wide bytes_to_copy either - use the memcpy there.
3737 */
3738 if (bytes_to_copy < 16 /*else use memcpy*/ &&
3739 png_isaligned(dp, png_uint_16) &&
3740 png_isaligned(sp, png_uint_16) &&
3741 bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
3742 bytes_to_jump % (sizeof (png_uint_16)) == 0)
3743 {
3744 /* Everything is aligned for png_uint_16 copies, but try for
3745 * png_uint_32 first.
3746 */
3747 if (png_isaligned(dp, png_uint_32) &&
3748 png_isaligned(sp, png_uint_32) &&
3749 bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
3750 bytes_to_jump % (sizeof (png_uint_32)) == 0)
3751 {
3752 png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
3753 png_const_uint_32p sp32 = png_aligncastconst(
3754 png_const_uint_32p, sp);
3755 size_t skip = (bytes_to_jump-bytes_to_copy) /
3756 (sizeof (png_uint_32));
3757
3758 do
3759 {
3760 size_t c = bytes_to_copy;
3761 do
3762 {
3763 *dp32++ = *sp32++;
3764 c -= (sizeof (png_uint_32));
3765 }
3766 while (c > 0);
3767
3768 if (row_width <= bytes_to_jump)
3769 return;
3770
3771 dp32 += skip;
3772 sp32 += skip;
3773 row_width -= bytes_to_jump;
3774 }
3775 while (bytes_to_copy <= row_width);
3776
3777 /* Get to here when the row_width truncates the final copy.
3778 * There will be 1-3 bytes left to copy, so don't try the
3779 * 16-bit loop below.
3780 */
3781 dp = (png_bytep)dp32;
3782 sp = (png_const_bytep)sp32;
3783 do
3784 *dp++ = *sp++;
3785 while (--row_width > 0);
3786 return;
3787 }
3788
3789 /* Else do it in 16-bit quantities, but only if the size is
3790 * not too large.
3791 */
3792 else
3793 {
3794 png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
3795 png_const_uint_16p sp16 = png_aligncastconst(
3796 png_const_uint_16p, sp);
3797 size_t skip = (bytes_to_jump-bytes_to_copy) /
3798 (sizeof (png_uint_16));
3799
3800 do
3801 {
3802 size_t c = bytes_to_copy;
3803 do
3804 {
3805 *dp16++ = *sp16++;
3806 c -= (sizeof (png_uint_16));
3807 }
3808 while (c > 0);
3809
3810 if (row_width <= bytes_to_jump)
3811 return;
3812
3813 dp16 += skip;
3814 sp16 += skip;
3815 row_width -= bytes_to_jump;
3816 }
3817 while (bytes_to_copy <= row_width);
3818
3819 /* End of row - 1 byte left, bytes_to_copy > row_width: */
3820 dp = (png_bytep)dp16;
3821 sp = (png_const_bytep)sp16;
3822 do
3823 *dp++ = *sp++;
3824 while (--row_width > 0);
3825 return;
3826 }
3827 }
3828 #endif /* ALIGN_TYPE code */
3829
3830 /* The true default - use a memcpy: */
3831 for (;;)
3832 {
3833 memcpy(dp, sp, bytes_to_copy);
3834
3835 if (row_width <= bytes_to_jump)
3836 return;
3837
3838 sp += bytes_to_jump;
3839 dp += bytes_to_jump;
3840 row_width -= bytes_to_jump;
3841 if (bytes_to_copy > row_width)
3842 bytes_to_copy = (unsigned int)/*SAFE*/row_width;
3843 }
3844 }
3845
3846 /* NOT REACHED*/
3847 } /* pixel_depth >= 8 */
3848
3849 /* Here if pixel_depth < 8 to check 'end_ptr' below. */
3850 }
3851 else
3852 #endif /* READ_INTERLACING */
3853
3854 /* If here then the switch above wasn't used so just memcpy the whole row
3855 * from the temporary row buffer (notice that this overwrites the end of the
3856 * destination row if it is a partial byte.)
3857 */
3858 memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
3859
3860 /* Restore the overwritten bits from the last byte if necessary. */
3861 if (end_ptr != NULL)
3862 *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
3863 }
3864
3865 #ifdef PNG_READ_INTERLACING_SUPPORTED
3866 void /* PRIVATE */
png_do_read_interlace(png_row_infop row_info,png_bytep row,int pass,png_uint_32 transformations)3867 png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
3868 png_uint_32 transformations /* Because these may affect the byte layout */)
3869 {
3870 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
3871 /* Offset to next interlace block */
3872 static const unsigned int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
3873
3874 png_debug(1, "in png_do_read_interlace");
3875 if (row != NULL && row_info != NULL)
3876 {
3877 png_uint_32 final_width;
3878
3879 final_width = row_info->width * png_pass_inc[pass];
3880
3881 switch (row_info->pixel_depth)
3882 {
3883 case 1:
3884 {
3885 png_bytep sp = row + (size_t)((row_info->width - 1) >> 3);
3886 png_bytep dp = row + (size_t)((final_width - 1) >> 3);
3887 unsigned int sshift, dshift;
3888 unsigned int s_start, s_end;
3889 int s_inc;
3890 int jstop = (int)png_pass_inc[pass];
3891 png_byte v;
3892 png_uint_32 i;
3893 int j;
3894
3895 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3896 if ((transformations & PNG_PACKSWAP) != 0)
3897 {
3898 sshift = ((row_info->width + 7) & 0x07);
3899 dshift = ((final_width + 7) & 0x07);
3900 s_start = 7;
3901 s_end = 0;
3902 s_inc = -1;
3903 }
3904
3905 else
3906 #endif
3907 {
3908 sshift = 7 - ((row_info->width + 7) & 0x07);
3909 dshift = 7 - ((final_width + 7) & 0x07);
3910 s_start = 0;
3911 s_end = 7;
3912 s_inc = 1;
3913 }
3914
3915 for (i = 0; i < row_info->width; i++)
3916 {
3917 v = (png_byte)((*sp >> sshift) & 0x01);
3918 for (j = 0; j < jstop; j++)
3919 {
3920 unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
3921 tmp |= (unsigned int)(v << dshift);
3922 *dp = (png_byte)(tmp & 0xff);
3923
3924 if (dshift == s_end)
3925 {
3926 dshift = s_start;
3927 dp--;
3928 }
3929
3930 else
3931 dshift = (unsigned int)((int)dshift + s_inc);
3932 }
3933
3934 if (sshift == s_end)
3935 {
3936 sshift = s_start;
3937 sp--;
3938 }
3939
3940 else
3941 sshift = (unsigned int)((int)sshift + s_inc);
3942 }
3943 break;
3944 }
3945
3946 case 2:
3947 {
3948 png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
3949 png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
3950 unsigned int sshift, dshift;
3951 unsigned int s_start, s_end;
3952 int s_inc;
3953 int jstop = (int)png_pass_inc[pass];
3954 png_uint_32 i;
3955
3956 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3957 if ((transformations & PNG_PACKSWAP) != 0)
3958 {
3959 sshift = (((row_info->width + 3) & 0x03) << 1);
3960 dshift = (((final_width + 3) & 0x03) << 1);
3961 s_start = 6;
3962 s_end = 0;
3963 s_inc = -2;
3964 }
3965
3966 else
3967 #endif
3968 {
3969 sshift = ((3 - ((row_info->width + 3) & 0x03)) << 1);
3970 dshift = ((3 - ((final_width + 3) & 0x03)) << 1);
3971 s_start = 0;
3972 s_end = 6;
3973 s_inc = 2;
3974 }
3975
3976 for (i = 0; i < row_info->width; i++)
3977 {
3978 png_byte v;
3979 int j;
3980
3981 v = (png_byte)((*sp >> sshift) & 0x03);
3982 for (j = 0; j < jstop; j++)
3983 {
3984 unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
3985 tmp |= (unsigned int)(v << dshift);
3986 *dp = (png_byte)(tmp & 0xff);
3987
3988 if (dshift == s_end)
3989 {
3990 dshift = s_start;
3991 dp--;
3992 }
3993
3994 else
3995 dshift = (unsigned int)((int)dshift + s_inc);
3996 }
3997
3998 if (sshift == s_end)
3999 {
4000 sshift = s_start;
4001 sp--;
4002 }
4003
4004 else
4005 sshift = (unsigned int)((int)sshift + s_inc);
4006 }
4007 break;
4008 }
4009
4010 case 4:
4011 {
4012 png_bytep sp = row + (size_t)((row_info->width - 1) >> 1);
4013 png_bytep dp = row + (size_t)((final_width - 1) >> 1);
4014 unsigned int sshift, dshift;
4015 unsigned int s_start, s_end;
4016 int s_inc;
4017 png_uint_32 i;
4018 int jstop = (int)png_pass_inc[pass];
4019
4020 #ifdef PNG_READ_PACKSWAP_SUPPORTED
4021 if ((transformations & PNG_PACKSWAP) != 0)
4022 {
4023 sshift = (((row_info->width + 1) & 0x01) << 2);
4024 dshift = (((final_width + 1) & 0x01) << 2);
4025 s_start = 4;
4026 s_end = 0;
4027 s_inc = -4;
4028 }
4029
4030 else
4031 #endif
4032 {
4033 sshift = ((1 - ((row_info->width + 1) & 0x01)) << 2);
4034 dshift = ((1 - ((final_width + 1) & 0x01)) << 2);
4035 s_start = 0;
4036 s_end = 4;
4037 s_inc = 4;
4038 }
4039
4040 for (i = 0; i < row_info->width; i++)
4041 {
4042 png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
4043 int j;
4044
4045 for (j = 0; j < jstop; j++)
4046 {
4047 unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
4048 tmp |= (unsigned int)(v << dshift);
4049 *dp = (png_byte)(tmp & 0xff);
4050
4051 if (dshift == s_end)
4052 {
4053 dshift = s_start;
4054 dp--;
4055 }
4056
4057 else
4058 dshift = (unsigned int)((int)dshift + s_inc);
4059 }
4060
4061 if (sshift == s_end)
4062 {
4063 sshift = s_start;
4064 sp--;
4065 }
4066
4067 else
4068 sshift = (unsigned int)((int)sshift + s_inc);
4069 }
4070 break;
4071 }
4072
4073 default:
4074 {
4075 size_t pixel_bytes = (row_info->pixel_depth >> 3);
4076
4077 png_bytep sp = row + (size_t)(row_info->width - 1)
4078 * pixel_bytes;
4079
4080 png_bytep dp = row + (size_t)(final_width - 1) * pixel_bytes;
4081
4082 int jstop = (int)png_pass_inc[pass];
4083 png_uint_32 i;
4084
4085 for (i = 0; i < row_info->width; i++)
4086 {
4087 png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
4088 int j;
4089
4090 memcpy(v, sp, pixel_bytes);
4091
4092 for (j = 0; j < jstop; j++)
4093 {
4094 memcpy(dp, v, pixel_bytes);
4095 dp -= pixel_bytes;
4096 }
4097
4098 sp -= pixel_bytes;
4099 }
4100 break;
4101 }
4102 }
4103
4104 row_info->width = final_width;
4105 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
4106 }
4107 #ifndef PNG_READ_PACKSWAP_SUPPORTED
4108 PNG_UNUSED(transformations) /* Silence compiler warning */
4109 #endif
4110 }
4111 #endif /* READ_INTERLACING */
4112
4113 static void
png_read_filter_row_sub(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)4114 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
4115 png_const_bytep prev_row)
4116 {
4117 size_t i;
4118 size_t istop = row_info->rowbytes;
4119 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
4120 png_bytep rp = row + bpp;
4121
4122 PNG_UNUSED(prev_row)
4123
4124 for (i = bpp; i < istop; i++)
4125 {
4126 *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
4127 rp++;
4128 }
4129 }
4130
4131 static void
png_read_filter_row_up(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)4132 png_read_filter_row_up(png_row_infop row_info, png_bytep row,
4133 png_const_bytep prev_row)
4134 {
4135 size_t i;
4136 size_t istop = row_info->rowbytes;
4137 png_bytep rp = row;
4138 png_const_bytep pp = prev_row;
4139
4140 for (i = 0; i < istop; i++)
4141 {
4142 *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
4143 rp++;
4144 }
4145 }
4146
4147 static void
png_read_filter_row_avg(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)4148 png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
4149 png_const_bytep prev_row)
4150 {
4151 size_t i;
4152 png_bytep rp = row;
4153 png_const_bytep pp = prev_row;
4154 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
4155 size_t istop = row_info->rowbytes - bpp;
4156
4157 for (i = 0; i < bpp; i++)
4158 {
4159 *rp = (png_byte)(((int)(*rp) +
4160 ((int)(*pp++) / 2 )) & 0xff);
4161
4162 rp++;
4163 }
4164
4165 for (i = 0; i < istop; i++)
4166 {
4167 *rp = (png_byte)(((int)(*rp) +
4168 (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
4169
4170 rp++;
4171 }
4172 }
4173
4174 static void
png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)4175 png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
4176 png_const_bytep prev_row)
4177 {
4178 png_bytep rp_end = row + row_info->rowbytes;
4179 int a, c;
4180
4181 /* First pixel/byte */
4182 c = *prev_row++;
4183 a = *row + c;
4184 *row++ = (png_byte)a;
4185
4186 /* Remainder */
4187 while (row < rp_end)
4188 {
4189 int b, pa, pb, pc, p;
4190
4191 a &= 0xff; /* From previous iteration or start */
4192 b = *prev_row++;
4193
4194 p = b - c;
4195 pc = a - c;
4196
4197 #ifdef PNG_USE_ABS
4198 pa = abs(p);
4199 pb = abs(pc);
4200 pc = abs(p + pc);
4201 #else
4202 pa = p < 0 ? -p : p;
4203 pb = pc < 0 ? -pc : pc;
4204 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
4205 #endif
4206
4207 /* Find the best predictor, the least of pa, pb, pc favoring the earlier
4208 * ones in the case of a tie.
4209 */
4210 if (pb < pa)
4211 {
4212 pa = pb; a = b;
4213 }
4214 if (pc < pa) a = c;
4215
4216 /* Calculate the current pixel in a, and move the previous row pixel to c
4217 * for the next time round the loop
4218 */
4219 c = b;
4220 a += *row;
4221 *row++ = (png_byte)a;
4222 }
4223 }
4224
4225 static void
png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)4226 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
4227 png_const_bytep prev_row)
4228 {
4229 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
4230 png_bytep rp_end = row + bpp;
4231
4232 /* Process the first pixel in the row completely (this is the same as 'up'
4233 * because there is only one candidate predictor for the first row).
4234 */
4235 while (row < rp_end)
4236 {
4237 int a = *row + *prev_row++;
4238 *row++ = (png_byte)a;
4239 }
4240
4241 /* Remainder */
4242 rp_end = rp_end + (row_info->rowbytes - bpp);
4243
4244 while (row < rp_end)
4245 {
4246 int a, b, c, pa, pb, pc, p;
4247
4248 c = *(prev_row - bpp);
4249 a = *(row - bpp);
4250 b = *prev_row++;
4251
4252 p = b - c;
4253 pc = a - c;
4254
4255 #ifdef PNG_USE_ABS
4256 pa = abs(p);
4257 pb = abs(pc);
4258 pc = abs(p + pc);
4259 #else
4260 pa = p < 0 ? -p : p;
4261 pb = pc < 0 ? -pc : pc;
4262 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
4263 #endif
4264
4265 if (pb < pa)
4266 {
4267 pa = pb; a = b;
4268 }
4269 if (pc < pa) a = c;
4270
4271 a += *row;
4272 *row++ = (png_byte)a;
4273 }
4274 }
4275
4276 static void
png_init_filter_functions(png_structrp pp)4277 png_init_filter_functions(png_structrp pp)
4278 /* This function is called once for every PNG image (except for PNG images
4279 * that only use PNG_FILTER_VALUE_NONE for all rows) to set the
4280 * implementations required to reverse the filtering of PNG rows. Reversing
4281 * the filter is the first transformation performed on the row data. It is
4282 * performed in place, therefore an implementation can be selected based on
4283 * the image pixel format. If the implementation depends on image width then
4284 * take care to ensure that it works correctly if the image is interlaced -
4285 * interlacing causes the actual row width to vary.
4286 */
4287 {
4288 unsigned int bpp = (pp->pixel_depth + 7) >> 3;
4289
4290 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
4291 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
4292 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
4293 if (bpp == 1)
4294 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
4295 png_read_filter_row_paeth_1byte_pixel;
4296 else
4297 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
4298 png_read_filter_row_paeth_multibyte_pixel;
4299
4300 #ifdef PNG_FILTER_OPTIMIZATIONS
4301 /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
4302 * call to install hardware optimizations for the above functions; simply
4303 * replace whatever elements of the pp->read_filter[] array with a hardware
4304 * specific (or, for that matter, generic) optimization.
4305 *
4306 * To see an example of this examine what configure.ac does when
4307 * --enable-arm-neon is specified on the command line.
4308 */
4309 PNG_FILTER_OPTIMIZATIONS(pp, bpp);
4310 #endif
4311 }
4312
4313 void /* PRIVATE */
png_read_filter_row(png_structrp pp,png_row_infop row_info,png_bytep row,png_const_bytep prev_row,int filter)4314 png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
4315 png_const_bytep prev_row, int filter)
4316 {
4317 /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
4318 * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
4319 * implementations. See png_init_filter_functions above.
4320 */
4321 if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
4322 {
4323 if (pp->read_filter[0] == NULL)
4324 png_init_filter_functions(pp);
4325
4326 pp->read_filter[filter-1](row_info, row, prev_row);
4327 }
4328 }
4329
4330 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
4331 void /* PRIVATE */
png_read_IDAT_data(png_structrp png_ptr,png_bytep output,png_alloc_size_t avail_out)4332 png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
4333 png_alloc_size_t avail_out)
4334 {
4335 /* Loop reading IDATs and decompressing the result into output[avail_out] */
4336 png_ptr->zstream.next_out = output;
4337 png_ptr->zstream.avail_out = 0; /* safety: set below */
4338
4339 if (output == NULL)
4340 avail_out = 0;
4341
4342 do
4343 {
4344 int ret;
4345 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
4346
4347 if (png_ptr->zstream.avail_in == 0)
4348 {
4349 uInt avail_in;
4350 png_bytep buffer;
4351
4352 #ifdef PNG_READ_APNG_SUPPORTED
4353 png_uint_32 bytes_to_skip = 0;
4354
4355 while (png_ptr->idat_size == 0 || bytes_to_skip != 0)
4356 {
4357 png_crc_finish(png_ptr, bytes_to_skip);
4358 bytes_to_skip = 0;
4359
4360 png_ptr->idat_size = png_read_chunk_header(png_ptr);
4361 if (png_ptr->num_frames_read == 0)
4362 {
4363 if (png_ptr->chunk_name != png_IDAT)
4364 png_error(png_ptr, "Not enough image data");
4365 }
4366 else
4367 {
4368 if (png_ptr->chunk_name == png_IEND)
4369 png_error(png_ptr, "Not enough image data");
4370 if (png_ptr->chunk_name != png_fdAT)
4371 {
4372 png_warning(png_ptr, "Skipped (ignored) a chunk "
4373 "between APNG chunks");
4374 bytes_to_skip = png_ptr->idat_size;
4375 continue;
4376 }
4377
4378 png_ensure_sequence_number(png_ptr, png_ptr->idat_size);
4379
4380 png_ptr->idat_size -= 4;
4381 }
4382 }
4383 #else
4384 while (png_ptr->idat_size == 0)
4385 {
4386 png_crc_finish(png_ptr, 0);
4387
4388 png_ptr->idat_size = png_read_chunk_header(png_ptr);
4389 /* This is an error even in the 'check' case because the code just
4390 * consumed a non-IDAT header.
4391 */
4392 if (png_ptr->chunk_name != png_IDAT)
4393 png_error(png_ptr, "Not enough image data");
4394 }
4395 #endif /* READ_APNG */
4396
4397 avail_in = png_ptr->IDAT_read_size;
4398
4399 if (avail_in > png_ptr->idat_size)
4400 avail_in = (uInt)png_ptr->idat_size;
4401
4402 /* A PNG with a gradually increasing IDAT size will defeat this attempt
4403 * to minimize memory usage by causing lots of re-allocs, but
4404 * realistically doing IDAT_read_size re-allocs is not likely to be a
4405 * big problem.
4406 */
4407 buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
4408
4409 png_crc_read(png_ptr, buffer, avail_in);
4410 png_ptr->idat_size -= avail_in;
4411
4412 png_ptr->zstream.next_in = buffer;
4413 png_ptr->zstream.avail_in = avail_in;
4414 }
4415
4416 /* And set up the output side. */
4417 if (output != NULL) /* standard read */
4418 {
4419 uInt out = ZLIB_IO_MAX;
4420
4421 if (out > avail_out)
4422 out = (uInt)avail_out;
4423
4424 avail_out -= out;
4425 png_ptr->zstream.avail_out = out;
4426 }
4427
4428 else /* after last row, checking for end */
4429 {
4430 png_ptr->zstream.next_out = tmpbuf;
4431 png_ptr->zstream.avail_out = (sizeof tmpbuf);
4432 }
4433
4434 /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
4435 * process. If the LZ stream is truncated the sequential reader will
4436 * terminally damage the stream, above, by reading the chunk header of the
4437 * following chunk (it then exits with png_error).
4438 *
4439 * TODO: deal more elegantly with truncated IDAT lists.
4440 */
4441 ret = PNG_INFLATE(png_ptr, Z_NO_FLUSH);
4442
4443 /* Take the unconsumed output back. */
4444 if (output != NULL)
4445 avail_out += png_ptr->zstream.avail_out;
4446
4447 else /* avail_out counts the extra bytes */
4448 avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
4449
4450 png_ptr->zstream.avail_out = 0;
4451
4452 if (ret == Z_STREAM_END)
4453 {
4454 /* Do this for safety; we won't read any more into this row. */
4455 png_ptr->zstream.next_out = NULL;
4456
4457 png_ptr->mode |= PNG_AFTER_IDAT;
4458 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4459 #ifdef PNG_READ_APNG_SUPPORTED
4460 png_ptr->num_frames_read++;
4461 #endif
4462
4463 if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
4464 png_chunk_benign_error(png_ptr, "Extra compressed data");
4465 break;
4466 }
4467
4468 if (ret != Z_OK)
4469 {
4470 png_zstream_error(png_ptr, ret);
4471
4472 if (output != NULL)
4473 png_chunk_error(png_ptr, png_ptr->zstream.msg);
4474
4475 else /* checking */
4476 {
4477 png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
4478 return;
4479 }
4480 }
4481 } while (avail_out > 0);
4482
4483 if (avail_out > 0)
4484 {
4485 /* The stream ended before the image; this is the same as too few IDATs so
4486 * should be handled the same way.
4487 */
4488 if (output != NULL)
4489 png_error(png_ptr, "Not enough image data");
4490
4491 else /* the deflate stream contained extra data */
4492 png_chunk_benign_error(png_ptr, "Too much image data");
4493 }
4494 }
4495
4496 void /* PRIVATE */
png_read_finish_IDAT(png_structrp png_ptr)4497 png_read_finish_IDAT(png_structrp png_ptr)
4498 {
4499 /* We don't need any more data and the stream should have ended, however the
4500 * LZ end code may actually not have been processed. In this case we must
4501 * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
4502 * may still remain to be consumed.
4503 */
4504 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
4505 {
4506 /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
4507 * the compressed stream, but the stream may be damaged too, so even after
4508 * this call we may need to terminate the zstream ownership.
4509 */
4510 png_read_IDAT_data(png_ptr, NULL, 0);
4511 png_ptr->zstream.next_out = NULL; /* safety */
4512
4513 /* Now clear everything out for safety; the following may not have been
4514 * done.
4515 */
4516 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
4517 {
4518 png_ptr->mode |= PNG_AFTER_IDAT;
4519 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4520 }
4521 }
4522
4523 /* If the zstream has not been released do it now *and* terminate the reading
4524 * of the final IDAT chunk.
4525 */
4526 if (png_ptr->zowner == png_IDAT)
4527 {
4528 /* Always do this; the pointers otherwise point into the read buffer. */
4529 png_ptr->zstream.next_in = NULL;
4530 png_ptr->zstream.avail_in = 0;
4531
4532 /* Now we no longer own the zstream. */
4533 png_ptr->zowner = 0;
4534
4535 /* The slightly weird semantics of the sequential IDAT reading is that we
4536 * are always in or at the end of an IDAT chunk, so we always need to do a
4537 * crc_finish here. If idat_size is non-zero we also need to read the
4538 * spurious bytes at the end of the chunk now.
4539 */
4540 (void)png_crc_finish(png_ptr, png_ptr->idat_size);
4541 }
4542 }
4543
4544 void /* PRIVATE */
png_read_finish_row(png_structrp png_ptr)4545 png_read_finish_row(png_structrp png_ptr)
4546 {
4547 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4548
4549 /* Start of interlace block */
4550 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4551
4552 /* Offset to next interlace block */
4553 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4554
4555 /* Start of interlace block in the y direction */
4556 static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4557
4558 /* Offset to next interlace block in the y direction */
4559 static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4560
4561 png_debug(1, "in png_read_finish_row");
4562 png_ptr->row_number++;
4563 if (png_ptr->row_number < png_ptr->num_rows)
4564 return;
4565
4566 if (png_ptr->interlaced != 0)
4567 {
4568 png_ptr->row_number = 0;
4569
4570 /* TO DO: don't do this if prev_row isn't needed (requires
4571 * read-ahead of the next row's filter byte.
4572 */
4573 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4574
4575 do
4576 {
4577 png_ptr->pass++;
4578
4579 if (png_ptr->pass >= 7)
4580 break;
4581
4582 png_ptr->iwidth = (png_ptr->width +
4583 png_pass_inc[png_ptr->pass] - 1 -
4584 png_pass_start[png_ptr->pass]) /
4585 png_pass_inc[png_ptr->pass];
4586
4587 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4588 {
4589 png_ptr->num_rows = (png_ptr->height +
4590 png_pass_yinc[png_ptr->pass] - 1 -
4591 png_pass_ystart[png_ptr->pass]) /
4592 png_pass_yinc[png_ptr->pass];
4593 }
4594
4595 else /* if (png_ptr->transformations & PNG_INTERLACE) */
4596 break; /* libpng deinterlacing sees every row */
4597
4598 } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
4599
4600 if (png_ptr->pass < 7)
4601 return;
4602 }
4603
4604 /* Here after at the end of the last row of the last pass. */
4605 png_read_finish_IDAT(png_ptr);
4606 }
4607 #endif /* SEQUENTIAL_READ */
4608
4609 void /* PRIVATE */
png_read_start_row(png_structrp png_ptr)4610 png_read_start_row(png_structrp png_ptr)
4611 {
4612 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4613
4614 /* Start of interlace block */
4615 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4616
4617 /* Offset to next interlace block */
4618 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4619
4620 /* Start of interlace block in the y direction */
4621 static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4622
4623 /* Offset to next interlace block in the y direction */
4624 static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4625
4626 unsigned int max_pixel_depth;
4627 size_t row_bytes;
4628
4629 png_debug(1, "in png_read_start_row");
4630
4631 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
4632 png_init_read_transformations(png_ptr);
4633 #endif
4634 if (png_ptr->interlaced != 0)
4635 {
4636 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4637 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
4638 png_pass_ystart[0]) / png_pass_yinc[0];
4639
4640 else
4641 png_ptr->num_rows = png_ptr->height;
4642
4643 png_ptr->iwidth = (png_ptr->width +
4644 png_pass_inc[png_ptr->pass] - 1 -
4645 png_pass_start[png_ptr->pass]) /
4646 png_pass_inc[png_ptr->pass];
4647 }
4648
4649 else
4650 {
4651 png_ptr->num_rows = png_ptr->height;
4652 png_ptr->iwidth = png_ptr->width;
4653 }
4654
4655 max_pixel_depth = (unsigned int)png_ptr->pixel_depth;
4656
4657 /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of
4658 * calculations to calculate the final pixel depth, then
4659 * png_do_read_transforms actually does the transforms. This means that the
4660 * code which effectively calculates this value is actually repeated in three
4661 * separate places. They must all match. Innocent changes to the order of
4662 * transformations can and will break libpng in a way that causes memory
4663 * overwrites.
4664 *
4665 * TODO: fix this.
4666 */
4667 #ifdef PNG_READ_PACK_SUPPORTED
4668 if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8)
4669 max_pixel_depth = 8;
4670 #endif
4671
4672 #ifdef PNG_READ_EXPAND_SUPPORTED
4673 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4674 {
4675 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4676 {
4677 if (png_ptr->num_trans != 0)
4678 max_pixel_depth = 32;
4679
4680 else
4681 max_pixel_depth = 24;
4682 }
4683
4684 else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4685 {
4686 if (max_pixel_depth < 8)
4687 max_pixel_depth = 8;
4688
4689 if (png_ptr->num_trans != 0)
4690 max_pixel_depth *= 2;
4691 }
4692
4693 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
4694 {
4695 if (png_ptr->num_trans != 0)
4696 {
4697 max_pixel_depth *= 4;
4698 max_pixel_depth /= 3;
4699 }
4700 }
4701 }
4702 #endif
4703
4704 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4705 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4706 {
4707 # ifdef PNG_READ_EXPAND_SUPPORTED
4708 /* In fact it is an error if it isn't supported, but checking is
4709 * the safe way.
4710 */
4711 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4712 {
4713 if (png_ptr->bit_depth < 16)
4714 max_pixel_depth *= 2;
4715 }
4716 else
4717 # endif
4718 png_ptr->transformations &= ~PNG_EXPAND_16;
4719 }
4720 #endif
4721
4722 #ifdef PNG_READ_FILLER_SUPPORTED
4723 if ((png_ptr->transformations & (PNG_FILLER)) != 0)
4724 {
4725 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4726 {
4727 if (max_pixel_depth <= 8)
4728 max_pixel_depth = 16;
4729
4730 else
4731 max_pixel_depth = 32;
4732 }
4733
4734 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
4735 png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4736 {
4737 if (max_pixel_depth <= 32)
4738 max_pixel_depth = 32;
4739
4740 else
4741 max_pixel_depth = 64;
4742 }
4743 }
4744 #endif
4745
4746 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4747 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
4748 {
4749 if (
4750 #ifdef PNG_READ_EXPAND_SUPPORTED
4751 (png_ptr->num_trans != 0 &&
4752 (png_ptr->transformations & PNG_EXPAND) != 0) ||
4753 #endif
4754 #ifdef PNG_READ_FILLER_SUPPORTED
4755 (png_ptr->transformations & (PNG_FILLER)) != 0 ||
4756 #endif
4757 png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4758 {
4759 if (max_pixel_depth <= 16)
4760 max_pixel_depth = 32;
4761
4762 else
4763 max_pixel_depth = 64;
4764 }
4765
4766 else
4767 {
4768 if (max_pixel_depth <= 8)
4769 {
4770 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4771 max_pixel_depth = 32;
4772
4773 else
4774 max_pixel_depth = 24;
4775 }
4776
4777 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4778 max_pixel_depth = 64;
4779
4780 else
4781 max_pixel_depth = 48;
4782 }
4783 }
4784 #endif
4785
4786 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
4787 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
4788 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
4789 {
4790 unsigned int user_pixel_depth = png_ptr->user_transform_depth *
4791 png_ptr->user_transform_channels;
4792
4793 if (user_pixel_depth > max_pixel_depth)
4794 max_pixel_depth = user_pixel_depth;
4795 }
4796 #endif
4797
4798 /* This value is stored in png_struct and double checked in the row read
4799 * code.
4800 */
4801 png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
4802 png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
4803
4804 /* Align the width on the next larger 8 pixels. Mainly used
4805 * for interlacing
4806 */
4807 row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
4808 /* Calculate the maximum bytes needed, adding a byte and a pixel
4809 * for safety's sake
4810 */
4811 row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
4812 1 + ((max_pixel_depth + 7) >> 3U);
4813
4814 #ifdef PNG_MAX_MALLOC_64K
4815 if (row_bytes > (png_uint_32)65536L)
4816 png_error(png_ptr, "This image requires a row greater than 64KB");
4817 #endif
4818
4819 if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
4820 {
4821 png_free(png_ptr, png_ptr->big_row_buf);
4822 png_free(png_ptr, png_ptr->big_prev_row);
4823
4824 if (png_ptr->interlaced != 0)
4825 png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
4826 row_bytes + 48);
4827
4828 else
4829 png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4830
4831 png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4832
4833 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
4834 /* Use 16-byte aligned memory for row_buf with at least 16 bytes
4835 * of padding before and after row_buf; treat prev_row similarly.
4836 * NOTE: the alignment is to the start of the pixels, one beyond the start
4837 * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this
4838 * was incorrect; the filter byte was aligned, which had the exact
4839 * opposite effect of that intended.
4840 */
4841 {
4842 png_bytep temp = png_ptr->big_row_buf + 32;
4843 int extra = (int)((temp - (png_bytep)0) & 0x0f);
4844 png_ptr->row_buf = temp - extra - 1/*filter byte*/;
4845
4846 temp = png_ptr->big_prev_row + 32;
4847 extra = (int)((temp - (png_bytep)0) & 0x0f);
4848 png_ptr->prev_row = temp - extra - 1/*filter byte*/;
4849 }
4850
4851 #else
4852 /* Use 31 bytes of padding before and 17 bytes after row_buf. */
4853 png_ptr->row_buf = png_ptr->big_row_buf + 31;
4854 png_ptr->prev_row = png_ptr->big_prev_row + 31;
4855 #endif
4856 png_ptr->old_big_row_buf_size = row_bytes + 48;
4857 }
4858
4859 #ifdef PNG_MAX_MALLOC_64K
4860 if (png_ptr->rowbytes > 65535)
4861 png_error(png_ptr, "This image requires a row greater than 64KB");
4862
4863 #endif
4864 if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
4865 png_error(png_ptr, "Row has too many bytes to allocate in memory");
4866
4867 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4868
4869 png_debug1(3, "width = %u,", png_ptr->width);
4870 png_debug1(3, "height = %u,", png_ptr->height);
4871 png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
4872 png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
4873 png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
4874 png_debug1(3, "irowbytes = %lu",
4875 (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
4876
4877 /* The sequential reader needs a buffer for IDAT, but the progressive reader
4878 * does not, so free the read buffer now regardless; the sequential reader
4879 * reallocates it on demand.
4880 */
4881 if (png_ptr->read_buffer != NULL)
4882 {
4883 png_bytep buffer = png_ptr->read_buffer;
4884
4885 png_ptr->read_buffer_size = 0;
4886 png_ptr->read_buffer = NULL;
4887 png_free(png_ptr, buffer);
4888 }
4889
4890 /* Finally claim the zstream for the inflate of the IDAT data, use the bits
4891 * value from the stream (note that this will result in a fatal error if the
4892 * IDAT stream has a bogus deflate header window_bits value, but this should
4893 * not be happening any longer!)
4894 */
4895 if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
4896 png_error(png_ptr, png_ptr->zstream.msg);
4897
4898 png_ptr->flags |= PNG_FLAG_ROW_INIT;
4899 }
4900
4901 #ifdef PNG_READ_APNG_SUPPORTED
4902 /* This function is to be called after the main IDAT set has been read and
4903 * before a new IDAT is read. It resets some parts of png_ptr
4904 * to make them usable by the read functions again */
4905 void /* PRIVATE */
png_read_reset(png_structp png_ptr)4906 png_read_reset(png_structp png_ptr)
4907 {
4908 png_ptr->mode &= ~PNG_HAVE_IDAT;
4909 png_ptr->mode &= ~PNG_AFTER_IDAT;
4910 png_ptr->row_number = 0;
4911 png_ptr->pass = 0;
4912 }
4913
4914 void /* PRIVATE */
png_read_reinit(png_structp png_ptr,png_infop info_ptr)4915 png_read_reinit(png_structp png_ptr, png_infop info_ptr)
4916 {
4917 png_ptr->width = info_ptr->next_frame_width;
4918 png_ptr->height = info_ptr->next_frame_height;
4919 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth,png_ptr->width);
4920 png_ptr->info_rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth,
4921 png_ptr->width);
4922 if (png_ptr->prev_row != NULL)
4923 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4924 }
4925
4926 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
4927 /* same as png_read_reset() but for the progressive reader */
4928 void /* PRIVATE */
png_progressive_read_reset(png_structp png_ptr)4929 png_progressive_read_reset(png_structp png_ptr)
4930 {
4931 #ifdef PNG_READ_INTERLACING_SUPPORTED
4932 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4933
4934 /* Start of interlace block */
4935 static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
4936
4937 /* Offset to next interlace block */
4938 static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
4939
4940 /* Start of interlace block in the y direction */
4941 static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
4942
4943 /* Offset to next interlace block in the y direction */
4944 static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
4945
4946 if (png_ptr->interlaced != 0)
4947 {
4948 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4949 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
4950 png_pass_ystart[0]) / png_pass_yinc[0];
4951 else
4952 png_ptr->num_rows = png_ptr->height;
4953
4954 png_ptr->iwidth = (png_ptr->width +
4955 png_pass_inc[png_ptr->pass] - 1 -
4956 png_pass_start[png_ptr->pass]) /
4957 png_pass_inc[png_ptr->pass];
4958 }
4959 else
4960 #endif /* READ_INTERLACING */
4961 {
4962 png_ptr->num_rows = png_ptr->height;
4963 png_ptr->iwidth = png_ptr->width;
4964 }
4965 png_ptr->flags &= ~PNG_FLAG_ZSTREAM_ENDED;
4966 if (inflateReset(&(png_ptr->zstream)) != Z_OK)
4967 png_error(png_ptr, "inflateReset failed");
4968 png_ptr->zstream.avail_in = 0;
4969 png_ptr->zstream.next_in = 0;
4970 png_ptr->zstream.next_out = png_ptr->row_buf;
4971 png_ptr->zstream.avail_out = (uInt)PNG_ROWBYTES(png_ptr->pixel_depth,
4972 png_ptr->iwidth) + 1;
4973 }
4974 #endif /* PROGRESSIVE_READ */
4975 #endif /* READ_APNG */
4976 #endif /* READ */
4977