1
2 /* pngrutil.c - utilities to read a PNG file
3 *
4 * Last changed in libpng 1.6.29 [March 16, 2017]
5 * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 *
13 * This file contains routines that are only called from within
14 * libpng itself during the course of reading an image.
15 */
16
17 #include "pngpriv.h"
18
19 #ifdef PNG_READ_SUPPORTED
20
21 png_uint_32 PNGAPI
png_get_uint_31(png_const_structrp png_ptr,png_const_bytep buf)22 png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
23 {
24 png_uint_32 uval = png_get_uint_32(buf);
25
26 if (uval > PNG_UINT_31_MAX)
27 png_error(png_ptr, "PNG unsigned integer out of range");
28
29 return (uval);
30 }
31
32 #if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
33 /* The following is a variation on the above for use with the fixed
34 * point values used for gAMA and cHRM. Instead of png_error it
35 * issues a warning and returns (-1) - an invalid value because both
36 * gAMA and cHRM use *unsigned* integers for fixed point values.
37 */
38 #define PNG_FIXED_ERROR (-1)
39
40 static png_fixed_point /* PRIVATE */
png_get_fixed_point(png_structrp png_ptr,png_const_bytep buf)41 png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
42 {
43 png_uint_32 uval = png_get_uint_32(buf);
44
45 if (uval <= PNG_UINT_31_MAX)
46 return (png_fixed_point)uval; /* known to be in range */
47
48 /* The caller can turn off the warning by passing NULL. */
49 if (png_ptr != NULL)
50 png_warning(png_ptr, "PNG fixed point integer out of range");
51
52 return PNG_FIXED_ERROR;
53 }
54 #endif
55
56 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
57 /* NOTE: the read macros will obscure these definitions, so that if
58 * PNG_USE_READ_MACROS is set the library will not use them internally,
59 * but the APIs will still be available externally.
60 *
61 * The parentheses around "PNGAPI function_name" in the following three
62 * functions are necessary because they allow the macros to co-exist with
63 * these (unused but exported) functions.
64 */
65
66 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
png_uint_32(PNGAPI png_get_uint_32)67 png_uint_32 (PNGAPI
68 png_get_uint_32)(png_const_bytep buf)
69 {
70 png_uint_32 uval =
71 ((png_uint_32)(*(buf )) << 24) +
72 ((png_uint_32)(*(buf + 1)) << 16) +
73 ((png_uint_32)(*(buf + 2)) << 8) +
74 ((png_uint_32)(*(buf + 3)) ) ;
75
76 return uval;
77 }
78
79 /* Grab a signed 32-bit integer from a buffer in big-endian format. The
80 * data is stored in the PNG file in two's complement format and there
81 * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
82 * the following code does a two's complement to native conversion.
83 */
png_int_32(PNGAPI png_get_int_32)84 png_int_32 (PNGAPI
85 png_get_int_32)(png_const_bytep buf)
86 {
87 png_uint_32 uval = png_get_uint_32(buf);
88 if ((uval & 0x80000000) == 0) /* non-negative */
89 return (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 accomodate 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 png_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 #ifdef PNG_IO_STATE_SUPPORTED
185 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
186 #endif
187
188 return length;
189 }
190
191 /* Read data, and (optionally) run it through the CRC. */
192 void /* PRIVATE */
png_crc_read(png_structrp png_ptr,png_bytep buf,png_uint_32 length)193 png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
194 {
195 if (png_ptr == NULL)
196 return;
197
198 png_read_data(png_ptr, buf, length);
199 png_calculate_crc(png_ptr, buf, length);
200 }
201
202 /* Optionally skip data and then check the CRC. Depending on whether we
203 * are reading an ancillary or critical chunk, and how the program has set
204 * things up, we may calculate the CRC on the data and print a message.
205 * Returns '1' if there was a CRC error, '0' otherwise.
206 */
207 int /* PRIVATE */
png_crc_finish(png_structrp png_ptr,png_uint_32 skip)208 png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
209 {
210 /* The size of the local buffer for inflate is a good guess as to a
211 * reasonable size to use for buffering reads from the application.
212 */
213 while (skip > 0)
214 {
215 png_uint_32 len;
216 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
217
218 len = (sizeof tmpbuf);
219 if (len > skip)
220 len = skip;
221 skip -= len;
222
223 png_crc_read(png_ptr, tmpbuf, len);
224 }
225
226 if (png_crc_error(png_ptr) != 0)
227 {
228 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0 ?
229 (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0 :
230 (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE) != 0)
231 {
232 png_chunk_warning(png_ptr, "CRC error");
233 }
234
235 else
236 png_chunk_error(png_ptr, "CRC error");
237
238 return (1);
239 }
240
241 return (0);
242 }
243
244 /* Compare the CRC stored in the PNG file with that calculated by libpng from
245 * the data it has read thus far.
246 */
247 int /* PRIVATE */
png_crc_error(png_structrp png_ptr)248 png_crc_error(png_structrp png_ptr)
249 {
250 png_byte crc_bytes[4];
251 png_uint_32 crc;
252 int need_crc = 1;
253
254 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
255 {
256 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
257 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
258 need_crc = 0;
259 }
260
261 else /* critical */
262 {
263 if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
264 need_crc = 0;
265 }
266
267 #ifdef PNG_IO_STATE_SUPPORTED
268 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
269 #endif
270
271 /* The chunk CRC must be serialized in a single I/O call. */
272 png_read_data(png_ptr, crc_bytes, 4);
273
274 if (need_crc != 0)
275 {
276 crc = png_get_uint_32(crc_bytes);
277 return ((int)(crc != png_ptr->crc));
278 }
279
280 else
281 return (0);
282 }
283
284 #if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
285 defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
286 defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
287 defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
288 /* Manage the read buffer; this simply reallocates the buffer if it is not small
289 * enough (or if it is not allocated). The routine returns a pointer to the
290 * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
291 * it will call png_error (via png_malloc) on failure. (warn == 2 means
292 * 'silent').
293 */
294 static png_bytep
png_read_buffer(png_structrp png_ptr,png_alloc_size_t new_size,int warn)295 png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
296 {
297 png_bytep buffer = png_ptr->read_buffer;
298
299 if (buffer != NULL && new_size > png_ptr->read_buffer_size)
300 {
301 png_ptr->read_buffer = NULL;
302 png_ptr->read_buffer = NULL;
303 png_ptr->read_buffer_size = 0;
304 png_free(png_ptr, buffer);
305 buffer = NULL;
306 }
307
308 if (buffer == NULL)
309 {
310 buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
311
312 if (buffer != NULL)
313 {
314 png_ptr->read_buffer = buffer;
315 png_ptr->read_buffer_size = new_size;
316 }
317
318 else if (warn < 2) /* else silent */
319 {
320 if (warn != 0)
321 png_chunk_warning(png_ptr, "insufficient memory to read chunk");
322
323 else
324 png_chunk_error(png_ptr, "insufficient memory to read chunk");
325 }
326 }
327
328 return buffer;
329 }
330 #endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
331
332 /* png_inflate_claim: claim the zstream for some nefarious purpose that involves
333 * decompression. Returns Z_OK on success, else a zlib error code. It checks
334 * the owner but, in final release builds, just issues a warning if some other
335 * chunk apparently owns the stream. Prior to release it does a png_error.
336 */
337 static int
png_inflate_claim(png_structrp png_ptr,png_uint_32 owner)338 png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
339 {
340 if (png_ptr->zowner != 0)
341 {
342 char msg[64];
343
344 PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
345 /* So the message that results is "<chunk> using zstream"; this is an
346 * internal error, but is very useful for debugging. i18n requirements
347 * are minimal.
348 */
349 (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
350 #if PNG_RELEASE_BUILD
351 png_chunk_warning(png_ptr, msg);
352 png_ptr->zowner = 0;
353 #else
354 png_chunk_error(png_ptr, msg);
355 #endif
356 }
357
358 /* Implementation note: unlike 'png_deflate_claim' this internal function
359 * does not take the size of the data as an argument. Some efficiency could
360 * be gained by using this when it is known *if* the zlib stream itself does
361 * not record the number; however, this is an illusion: the original writer
362 * of the PNG may have selected a lower window size, and we really must
363 * follow that because, for systems with with limited capabilities, we
364 * would otherwise reject the application's attempts to use a smaller window
365 * size (zlib doesn't have an interface to say "this or lower"!).
366 *
367 * inflateReset2 was added to zlib 1.2.4; before this the window could not be
368 * reset, therefore it is necessary to always allocate the maximum window
369 * size with earlier zlibs just in case later compressed chunks need it.
370 */
371 {
372 int ret; /* zlib return code */
373 #if ZLIB_VERNUM >= 0x1240
374 int window_bits = 0;
375
376 # if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
377 if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
378 PNG_OPTION_ON)
379 {
380 window_bits = 15;
381 png_ptr->zstream_start = 0; /* fixed window size */
382 }
383
384 else
385 {
386 png_ptr->zstream_start = 1;
387 }
388 # endif
389
390 #endif /* ZLIB_VERNUM >= 0x1240 */
391
392 /* Set this for safety, just in case the previous owner left pointers to
393 * memory allocations.
394 */
395 png_ptr->zstream.next_in = NULL;
396 png_ptr->zstream.avail_in = 0;
397 png_ptr->zstream.next_out = NULL;
398 png_ptr->zstream.avail_out = 0;
399
400 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
401 {
402 #if ZLIB_VERNUM >= 0x1240
403 ret = inflateReset2(&png_ptr->zstream, window_bits);
404 #else
405 ret = inflateReset(&png_ptr->zstream);
406 #endif
407 }
408
409 else
410 {
411 #if ZLIB_VERNUM >= 0x1240
412 ret = inflateInit2(&png_ptr->zstream, window_bits);
413 #else
414 ret = inflateInit(&png_ptr->zstream);
415 #endif
416
417 if (ret == Z_OK)
418 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
419 }
420
421 #if ZLIB_VERNUM >= 0x1290 && \
422 defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_IGNORE_ADLER32)
423 if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON)
424 /* Turn off validation of the ADLER32 checksum in IDAT chunks */
425 ret = inflateValidate(&png_ptr->zstream, 0);
426 #endif
427
428 if (ret == Z_OK)
429 png_ptr->zowner = owner;
430
431 else
432 png_zstream_error(png_ptr, ret);
433
434 return ret;
435 }
436
437 #ifdef window_bits
438 # undef window_bits
439 #endif
440 }
441
442 #if ZLIB_VERNUM >= 0x1240
443 /* Handle the start of the inflate stream if we called inflateInit2(strm,0);
444 * in this case some zlib versions skip validation of the CINFO field and, in
445 * certain circumstances, libpng may end up displaying an invalid image, in
446 * contrast to implementations that call zlib in the normal way (e.g. libpng
447 * 1.5).
448 */
449 int /* PRIVATE */
png_zlib_inflate(png_structrp png_ptr,int flush)450 png_zlib_inflate(png_structrp png_ptr, int flush)
451 {
452 if (png_ptr->zstream_start && png_ptr->zstream.avail_in > 0)
453 {
454 if ((*png_ptr->zstream.next_in >> 4) > 7)
455 {
456 png_ptr->zstream.msg = "invalid window size (libpng)";
457 return Z_DATA_ERROR;
458 }
459
460 png_ptr->zstream_start = 0;
461 }
462
463 return inflate(&png_ptr->zstream, flush);
464 }
465 #endif /* Zlib >= 1.2.4 */
466
467 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
468 #if defined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED)
469 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
470 * allow the caller to do multiple calls if required. If the 'finish' flag is
471 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
472 * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
473 * Z_OK or Z_STREAM_END will be returned on success.
474 *
475 * The input and output sizes are updated to the actual amounts of data consumed
476 * or written, not the amount available (as in a z_stream). The data pointers
477 * are not changed, so the next input is (data+input_size) and the next
478 * available output is (output+output_size).
479 */
480 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)481 png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
482 /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
483 /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
484 {
485 if (png_ptr->zowner == owner) /* Else not claimed */
486 {
487 int ret;
488 png_alloc_size_t avail_out = *output_size_ptr;
489 png_uint_32 avail_in = *input_size_ptr;
490
491 /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
492 * can't even necessarily handle 65536 bytes) because the type uInt is
493 * "16 bits or more". Consequently it is necessary to chunk the input to
494 * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
495 * maximum value that can be stored in a uInt.) It is possible to set
496 * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
497 * a performance advantage, because it reduces the amount of data accessed
498 * at each step and that may give the OS more time to page it in.
499 */
500 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
501 /* avail_in and avail_out are set below from 'size' */
502 png_ptr->zstream.avail_in = 0;
503 png_ptr->zstream.avail_out = 0;
504
505 /* Read directly into the output if it is available (this is set to
506 * a local buffer below if output is NULL).
507 */
508 if (output != NULL)
509 png_ptr->zstream.next_out = output;
510
511 do
512 {
513 uInt avail;
514 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
515
516 /* zlib INPUT BUFFER */
517 /* The setting of 'avail_in' used to be outside the loop; by setting it
518 * inside it is possible to chunk the input to zlib and simply rely on
519 * zlib to advance the 'next_in' pointer. This allows arbitrary
520 * amounts of data to be passed through zlib at the unavoidable cost of
521 * requiring a window save (memcpy of up to 32768 output bytes)
522 * every ZLIB_IO_MAX input bytes.
523 */
524 avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
525
526 avail = ZLIB_IO_MAX;
527
528 if (avail_in < avail)
529 avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
530
531 avail_in -= avail;
532 png_ptr->zstream.avail_in = avail;
533
534 /* zlib OUTPUT BUFFER */
535 avail_out += png_ptr->zstream.avail_out; /* not written last time */
536
537 avail = ZLIB_IO_MAX; /* maximum zlib can process */
538
539 if (output == NULL)
540 {
541 /* Reset the output buffer each time round if output is NULL and
542 * make available the full buffer, up to 'remaining_space'
543 */
544 png_ptr->zstream.next_out = local_buffer;
545 if ((sizeof local_buffer) < avail)
546 avail = (sizeof local_buffer);
547 }
548
549 if (avail_out < avail)
550 avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
551
552 png_ptr->zstream.avail_out = avail;
553 avail_out -= avail;
554
555 /* zlib inflate call */
556 /* In fact 'avail_out' may be 0 at this point, that happens at the end
557 * of the read when the final LZ end code was not passed at the end of
558 * the previous chunk of input data. Tell zlib if we have reached the
559 * end of the output buffer.
560 */
561 ret = PNG_INFLATE(png_ptr, avail_out > 0 ? Z_NO_FLUSH :
562 (finish ? Z_FINISH : Z_SYNC_FLUSH));
563 } while (ret == Z_OK);
564
565 /* For safety kill the local buffer pointer now */
566 if (output == NULL)
567 png_ptr->zstream.next_out = NULL;
568
569 /* Claw back the 'size' and 'remaining_space' byte counts. */
570 avail_in += png_ptr->zstream.avail_in;
571 avail_out += png_ptr->zstream.avail_out;
572
573 /* Update the input and output sizes; the updated values are the amount
574 * consumed or written, effectively the inverse of what zlib uses.
575 */
576 if (avail_out > 0)
577 *output_size_ptr -= avail_out;
578
579 if (avail_in > 0)
580 *input_size_ptr -= avail_in;
581
582 /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
583 png_zstream_error(png_ptr, ret);
584 return ret;
585 }
586
587 else
588 {
589 /* This is a bad internal error. The recovery assigns to the zstream msg
590 * pointer, which is not owned by the caller, but this is safe; it's only
591 * used on errors!
592 */
593 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
594 return Z_STREAM_ERROR;
595 }
596 }
597
598 /*
599 * Decompress trailing data in a chunk. The assumption is that read_buffer
600 * points at an allocated area holding the contents of a chunk with a
601 * trailing compressed part. What we get back is an allocated area
602 * holding the original prefix part and an uncompressed version of the
603 * trailing part (the malloc area passed in is freed).
604 */
605 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)606 png_decompress_chunk(png_structrp png_ptr,
607 png_uint_32 chunklength, png_uint_32 prefix_size,
608 png_alloc_size_t *newlength /* must be initialized to the maximum! */,
609 int terminate /*add a '\0' to the end of the uncompressed data*/)
610 {
611 /* TODO: implement different limits for different types of chunk.
612 *
613 * The caller supplies *newlength set to the maximum length of the
614 * uncompressed data, but this routine allocates space for the prefix and
615 * maybe a '\0' terminator too. We have to assume that 'prefix_size' is
616 * limited only by the maximum chunk size.
617 */
618 png_alloc_size_t limit = PNG_SIZE_MAX;
619
620 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
621 if (png_ptr->user_chunk_malloc_max > 0 &&
622 png_ptr->user_chunk_malloc_max < limit)
623 limit = png_ptr->user_chunk_malloc_max;
624 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
625 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
626 limit = PNG_USER_CHUNK_MALLOC_MAX;
627 # endif
628
629 if (limit >= prefix_size + (terminate != 0))
630 {
631 int ret;
632
633 limit -= prefix_size + (terminate != 0);
634
635 if (limit < *newlength)
636 *newlength = limit;
637
638 /* Now try to claim the stream. */
639 ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
640
641 if (ret == Z_OK)
642 {
643 png_uint_32 lzsize = chunklength - prefix_size;
644
645 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
646 /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
647 /* output: */ NULL, newlength);
648
649 if (ret == Z_STREAM_END)
650 {
651 /* Use 'inflateReset' here, not 'inflateReset2' because this
652 * preserves the previously decided window size (otherwise it would
653 * be necessary to store the previous window size.) In practice
654 * this doesn't matter anyway, because png_inflate will call inflate
655 * with Z_FINISH in almost all cases, so the window will not be
656 * maintained.
657 */
658 if (inflateReset(&png_ptr->zstream) == Z_OK)
659 {
660 /* Because of the limit checks above we know that the new,
661 * expanded, size will fit in a size_t (let alone an
662 * png_alloc_size_t). Use png_malloc_base here to avoid an
663 * extra OOM message.
664 */
665 png_alloc_size_t new_size = *newlength;
666 png_alloc_size_t buffer_size = prefix_size + new_size +
667 (terminate != 0);
668 png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
669 buffer_size));
670
671 if (text != NULL)
672 {
673 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
674 png_ptr->read_buffer + prefix_size, &lzsize,
675 text + prefix_size, newlength);
676
677 if (ret == Z_STREAM_END)
678 {
679 if (new_size == *newlength)
680 {
681 if (terminate != 0)
682 text[prefix_size + *newlength] = 0;
683
684 if (prefix_size > 0)
685 memcpy(text, png_ptr->read_buffer, prefix_size);
686
687 {
688 png_bytep old_ptr = png_ptr->read_buffer;
689
690 png_ptr->read_buffer = text;
691 png_ptr->read_buffer_size = buffer_size;
692 text = old_ptr; /* freed below */
693 }
694 }
695
696 else
697 {
698 /* The size changed on the second read, there can be no
699 * guarantee that anything is correct at this point.
700 * The 'msg' pointer has been set to "unexpected end of
701 * LZ stream", which is fine, but return an error code
702 * that the caller won't accept.
703 */
704 ret = PNG_UNEXPECTED_ZLIB_RETURN;
705 }
706 }
707
708 else if (ret == Z_OK)
709 ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
710
711 /* Free the text pointer (this is the old read_buffer on
712 * success)
713 */
714 png_free(png_ptr, text);
715
716 /* This really is very benign, but it's still an error because
717 * the extra space may otherwise be used as a Trojan Horse.
718 */
719 if (ret == Z_STREAM_END &&
720 chunklength - prefix_size != lzsize)
721 png_chunk_benign_error(png_ptr, "extra compressed data");
722 }
723
724 else
725 {
726 /* Out of memory allocating the buffer */
727 ret = Z_MEM_ERROR;
728 png_zstream_error(png_ptr, Z_MEM_ERROR);
729 }
730 }
731
732 else
733 {
734 /* inflateReset failed, store the error message */
735 png_zstream_error(png_ptr, ret);
736
737 if (ret == Z_STREAM_END)
738 ret = PNG_UNEXPECTED_ZLIB_RETURN;
739 }
740 }
741
742 else if (ret == Z_OK)
743 ret = PNG_UNEXPECTED_ZLIB_RETURN;
744
745 /* Release the claimed stream */
746 png_ptr->zowner = 0;
747 }
748
749 else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
750 ret = PNG_UNEXPECTED_ZLIB_RETURN;
751
752 return ret;
753 }
754
755 else
756 {
757 /* Application/configuration limits exceeded */
758 png_zstream_error(png_ptr, Z_MEM_ERROR);
759 return Z_MEM_ERROR;
760 }
761 }
762 #endif /* READ_zTXt || READ_iTXt */
763 #endif /* READ_COMPRESSED_TEXT */
764
765 #ifdef PNG_READ_iCCP_SUPPORTED
766 /* Perform a partial read and decompress, producing 'avail_out' bytes and
767 * reading from the current chunk as required.
768 */
769 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)770 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
771 png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
772 int finish)
773 {
774 if (png_ptr->zowner == png_ptr->chunk_name)
775 {
776 int ret;
777
778 /* next_in and avail_in must have been initialized by the caller. */
779 png_ptr->zstream.next_out = next_out;
780 png_ptr->zstream.avail_out = 0; /* set in the loop */
781
782 do
783 {
784 if (png_ptr->zstream.avail_in == 0)
785 {
786 if (read_size > *chunk_bytes)
787 read_size = (uInt)*chunk_bytes;
788 *chunk_bytes -= read_size;
789
790 if (read_size > 0)
791 png_crc_read(png_ptr, read_buffer, read_size);
792
793 png_ptr->zstream.next_in = read_buffer;
794 png_ptr->zstream.avail_in = read_size;
795 }
796
797 if (png_ptr->zstream.avail_out == 0)
798 {
799 uInt avail = ZLIB_IO_MAX;
800 if (avail > *out_size)
801 avail = (uInt)*out_size;
802 *out_size -= avail;
803
804 png_ptr->zstream.avail_out = avail;
805 }
806
807 /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
808 * the available output is produced; this allows reading of truncated
809 * streams.
810 */
811 ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ?
812 Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
813 }
814 while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
815
816 *out_size += png_ptr->zstream.avail_out;
817 png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
818
819 /* Ensure the error message pointer is always set: */
820 png_zstream_error(png_ptr, ret);
821 return ret;
822 }
823
824 else
825 {
826 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
827 return Z_STREAM_ERROR;
828 }
829 }
830 #endif /* READ_iCCP */
831
832 /* Read and check the IDHR chunk */
833
834 void /* PRIVATE */
png_handle_IHDR(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)835 png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
836 {
837 png_byte buf[13];
838 png_uint_32 width, height;
839 int bit_depth, color_type, compression_type, filter_type;
840 int interlace_type;
841
842 png_debug(1, "in png_handle_IHDR");
843
844 if ((png_ptr->mode & PNG_HAVE_IHDR) != 0)
845 png_chunk_error(png_ptr, "out of place");
846
847 /* Check the length */
848 if (length != 13)
849 png_chunk_error(png_ptr, "invalid");
850
851 png_ptr->mode |= PNG_HAVE_IHDR;
852
853 png_crc_read(png_ptr, buf, 13);
854 png_crc_finish(png_ptr, 0);
855
856 width = png_get_uint_31(png_ptr, buf);
857 height = png_get_uint_31(png_ptr, buf + 4);
858 bit_depth = buf[8];
859 color_type = buf[9];
860 compression_type = buf[10];
861 filter_type = buf[11];
862 interlace_type = buf[12];
863
864 /* Set internal variables */
865 png_ptr->width = width;
866 png_ptr->height = height;
867 png_ptr->bit_depth = (png_byte)bit_depth;
868 png_ptr->interlaced = (png_byte)interlace_type;
869 png_ptr->color_type = (png_byte)color_type;
870 #ifdef PNG_MNG_FEATURES_SUPPORTED
871 png_ptr->filter_type = (png_byte)filter_type;
872 #endif
873 png_ptr->compression_type = (png_byte)compression_type;
874
875 /* Find number of channels */
876 switch (png_ptr->color_type)
877 {
878 default: /* invalid, png_set_IHDR calls png_error */
879 case PNG_COLOR_TYPE_GRAY:
880 case PNG_COLOR_TYPE_PALETTE:
881 png_ptr->channels = 1;
882 break;
883
884 case PNG_COLOR_TYPE_RGB:
885 png_ptr->channels = 3;
886 break;
887
888 case PNG_COLOR_TYPE_GRAY_ALPHA:
889 png_ptr->channels = 2;
890 break;
891
892 case PNG_COLOR_TYPE_RGB_ALPHA:
893 png_ptr->channels = 4;
894 break;
895 }
896
897 /* Set up other useful info */
898 png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels);
899 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
900 png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
901 png_debug1(3, "channels = %d", png_ptr->channels);
902 png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
903 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
904 color_type, interlace_type, compression_type, filter_type);
905 }
906
907 /* Read and check the palette */
908 void /* PRIVATE */
png_handle_PLTE(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)909 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
910 {
911 png_color palette[PNG_MAX_PALETTE_LENGTH];
912 int max_palette_length, num, i;
913 #ifdef PNG_POINTER_INDEXING_SUPPORTED
914 png_colorp pal_ptr;
915 #endif
916
917 png_debug(1, "in png_handle_PLTE");
918
919 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
920 png_chunk_error(png_ptr, "missing IHDR");
921
922 /* Moved to before the 'after IDAT' check below because otherwise duplicate
923 * PLTE chunks are potentially ignored (the spec says there shall not be more
924 * than one PLTE, the error is not treated as benign, so this check trumps
925 * the requirement that PLTE appears before IDAT.)
926 */
927 else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
928 png_chunk_error(png_ptr, "duplicate");
929
930 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
931 {
932 /* This is benign because the non-benign error happened before, when an
933 * IDAT was encountered in a color-mapped image with no PLTE.
934 */
935 png_crc_finish(png_ptr, length);
936 png_chunk_benign_error(png_ptr, "out of place");
937 return;
938 }
939
940 png_ptr->mode |= PNG_HAVE_PLTE;
941
942 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
943 {
944 png_crc_finish(png_ptr, length);
945 png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
946 return;
947 }
948
949 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
950 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
951 {
952 png_crc_finish(png_ptr, length);
953 return;
954 }
955 #endif
956
957 if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
958 {
959 png_crc_finish(png_ptr, length);
960
961 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
962 png_chunk_benign_error(png_ptr, "invalid");
963
964 else
965 png_chunk_error(png_ptr, "invalid");
966
967 return;
968 }
969
970 /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
971 num = (int)length / 3;
972
973 /* If the palette has 256 or fewer entries but is too large for the bit
974 * depth, we don't issue an error, to preserve the behavior of previous
975 * libpng versions. We silently truncate the unused extra palette entries
976 * here.
977 */
978 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
979 max_palette_length = (1 << png_ptr->bit_depth);
980 else
981 max_palette_length = PNG_MAX_PALETTE_LENGTH;
982
983 if (num > max_palette_length)
984 num = max_palette_length;
985
986 #ifdef PNG_POINTER_INDEXING_SUPPORTED
987 for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
988 {
989 png_byte buf[3];
990
991 png_crc_read(png_ptr, buf, 3);
992 pal_ptr->red = buf[0];
993 pal_ptr->green = buf[1];
994 pal_ptr->blue = buf[2];
995 }
996 #else
997 for (i = 0; i < num; i++)
998 {
999 png_byte buf[3];
1000
1001 png_crc_read(png_ptr, buf, 3);
1002 /* Don't depend upon png_color being any order */
1003 palette[i].red = buf[0];
1004 palette[i].green = buf[1];
1005 palette[i].blue = buf[2];
1006 }
1007 #endif
1008
1009 /* If we actually need the PLTE chunk (ie for a paletted image), we do
1010 * whatever the normal CRC configuration tells us. However, if we
1011 * have an RGB image, the PLTE can be considered ancillary, so
1012 * we will act as though it is.
1013 */
1014 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1015 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1016 #endif
1017 {
1018 png_crc_finish(png_ptr, (png_uint_32) (length - (unsigned int)num * 3));
1019 }
1020
1021 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
1022 else if (png_crc_error(png_ptr) != 0) /* Only if we have a CRC error */
1023 {
1024 /* If we don't want to use the data from an ancillary chunk,
1025 * we have two options: an error abort, or a warning and we
1026 * ignore the data in this chunk (which should be OK, since
1027 * it's considered ancillary for a RGB or RGBA image).
1028 *
1029 * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
1030 * chunk type to determine whether to check the ancillary or the critical
1031 * flags.
1032 */
1033 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
1034 {
1035 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0)
1036 return;
1037
1038 else
1039 png_chunk_error(png_ptr, "CRC error");
1040 }
1041
1042 /* Otherwise, we (optionally) emit a warning and use the chunk. */
1043 else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
1044 png_chunk_warning(png_ptr, "CRC error");
1045 }
1046 #endif
1047
1048 /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
1049 * own copy of the palette. This has the side effect that when png_start_row
1050 * is called (this happens after any call to png_read_update_info) the
1051 * info_ptr palette gets changed. This is extremely unexpected and
1052 * confusing.
1053 *
1054 * Fix this by not sharing the palette in this way.
1055 */
1056 png_set_PLTE(png_ptr, info_ptr, palette, num);
1057
1058 /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
1059 * IDAT. Prior to 1.6.0 this was not checked; instead the code merely
1060 * checked the apparent validity of a tRNS chunk inserted before PLTE on a
1061 * palette PNG. 1.6.0 attempts to rigorously follow the standard and
1062 * therefore does a benign error if the erroneous condition is detected *and*
1063 * cancels the tRNS if the benign error returns. The alternative is to
1064 * amend the standard since it would be rather hypocritical of the standards
1065 * maintainers to ignore it.
1066 */
1067 #ifdef PNG_READ_tRNS_SUPPORTED
1068 if (png_ptr->num_trans > 0 ||
1069 (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
1070 {
1071 /* Cancel this because otherwise it would be used if the transforms
1072 * require it. Don't cancel the 'valid' flag because this would prevent
1073 * detection of duplicate chunks.
1074 */
1075 png_ptr->num_trans = 0;
1076
1077 if (info_ptr != NULL)
1078 info_ptr->num_trans = 0;
1079
1080 png_chunk_benign_error(png_ptr, "tRNS must be after");
1081 }
1082 #endif
1083
1084 #ifdef PNG_READ_hIST_SUPPORTED
1085 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
1086 png_chunk_benign_error(png_ptr, "hIST must be after");
1087 #endif
1088
1089 #ifdef PNG_READ_bKGD_SUPPORTED
1090 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1091 png_chunk_benign_error(png_ptr, "bKGD must be after");
1092 #endif
1093 }
1094
1095 void /* PRIVATE */
png_handle_IEND(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1096 png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1097 {
1098 png_debug(1, "in png_handle_IEND");
1099
1100 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0 ||
1101 (png_ptr->mode & PNG_HAVE_IDAT) == 0)
1102 png_chunk_error(png_ptr, "out of place");
1103
1104 png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
1105
1106 png_crc_finish(png_ptr, length);
1107
1108 if (length != 0)
1109 png_chunk_benign_error(png_ptr, "invalid");
1110
1111 PNG_UNUSED(info_ptr)
1112 }
1113
1114 #ifdef PNG_READ_gAMA_SUPPORTED
1115 void /* PRIVATE */
png_handle_gAMA(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1116 png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1117 {
1118 png_fixed_point igamma;
1119 png_byte buf[4];
1120
1121 png_debug(1, "in png_handle_gAMA");
1122
1123 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1124 png_chunk_error(png_ptr, "missing IHDR");
1125
1126 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1127 {
1128 png_crc_finish(png_ptr, length);
1129 png_chunk_benign_error(png_ptr, "out of place");
1130 return;
1131 }
1132
1133 if (length != 4)
1134 {
1135 png_crc_finish(png_ptr, length);
1136 png_chunk_benign_error(png_ptr, "invalid");
1137 return;
1138 }
1139
1140 png_crc_read(png_ptr, buf, 4);
1141
1142 if (png_crc_finish(png_ptr, 0) != 0)
1143 return;
1144
1145 igamma = png_get_fixed_point(NULL, buf);
1146
1147 png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
1148 png_colorspace_sync(png_ptr, info_ptr);
1149 }
1150 #endif
1151
1152 #ifdef PNG_READ_sBIT_SUPPORTED
1153 void /* PRIVATE */
png_handle_sBIT(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1154 png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1155 {
1156 unsigned int truelen, i;
1157 png_byte sample_depth;
1158 png_byte buf[4];
1159
1160 png_debug(1, "in png_handle_sBIT");
1161
1162 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1163 png_chunk_error(png_ptr, "missing IHDR");
1164
1165 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1166 {
1167 png_crc_finish(png_ptr, length);
1168 png_chunk_benign_error(png_ptr, "out of place");
1169 return;
1170 }
1171
1172 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT) != 0)
1173 {
1174 png_crc_finish(png_ptr, length);
1175 png_chunk_benign_error(png_ptr, "duplicate");
1176 return;
1177 }
1178
1179 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1180 {
1181 truelen = 3;
1182 sample_depth = 8;
1183 }
1184
1185 else
1186 {
1187 truelen = png_ptr->channels;
1188 sample_depth = png_ptr->bit_depth;
1189 }
1190
1191 if (length != truelen || length > 4)
1192 {
1193 png_chunk_benign_error(png_ptr, "invalid");
1194 png_crc_finish(png_ptr, length);
1195 return;
1196 }
1197
1198 buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
1199 png_crc_read(png_ptr, buf, truelen);
1200
1201 if (png_crc_finish(png_ptr, 0) != 0)
1202 return;
1203
1204 for (i=0; i<truelen; ++i)
1205 {
1206 if (buf[i] == 0 || buf[i] > sample_depth)
1207 {
1208 png_chunk_benign_error(png_ptr, "invalid");
1209 return;
1210 }
1211 }
1212
1213 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1214 {
1215 png_ptr->sig_bit.red = buf[0];
1216 png_ptr->sig_bit.green = buf[1];
1217 png_ptr->sig_bit.blue = buf[2];
1218 png_ptr->sig_bit.alpha = buf[3];
1219 }
1220
1221 else
1222 {
1223 png_ptr->sig_bit.gray = buf[0];
1224 png_ptr->sig_bit.red = buf[0];
1225 png_ptr->sig_bit.green = buf[0];
1226 png_ptr->sig_bit.blue = buf[0];
1227 png_ptr->sig_bit.alpha = buf[1];
1228 }
1229
1230 png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
1231 }
1232 #endif
1233
1234 #ifdef PNG_READ_cHRM_SUPPORTED
1235 void /* PRIVATE */
png_handle_cHRM(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1236 png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1237 {
1238 png_byte buf[32];
1239 png_xy xy;
1240
1241 png_debug(1, "in png_handle_cHRM");
1242
1243 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1244 png_chunk_error(png_ptr, "missing IHDR");
1245
1246 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1247 {
1248 png_crc_finish(png_ptr, length);
1249 png_chunk_benign_error(png_ptr, "out of place");
1250 return;
1251 }
1252
1253 if (length != 32)
1254 {
1255 png_crc_finish(png_ptr, length);
1256 png_chunk_benign_error(png_ptr, "invalid");
1257 return;
1258 }
1259
1260 png_crc_read(png_ptr, buf, 32);
1261
1262 if (png_crc_finish(png_ptr, 0) != 0)
1263 return;
1264
1265 xy.whitex = png_get_fixed_point(NULL, buf);
1266 xy.whitey = png_get_fixed_point(NULL, buf + 4);
1267 xy.redx = png_get_fixed_point(NULL, buf + 8);
1268 xy.redy = png_get_fixed_point(NULL, buf + 12);
1269 xy.greenx = png_get_fixed_point(NULL, buf + 16);
1270 xy.greeny = png_get_fixed_point(NULL, buf + 20);
1271 xy.bluex = png_get_fixed_point(NULL, buf + 24);
1272 xy.bluey = png_get_fixed_point(NULL, buf + 28);
1273
1274 if (xy.whitex == PNG_FIXED_ERROR ||
1275 xy.whitey == PNG_FIXED_ERROR ||
1276 xy.redx == PNG_FIXED_ERROR ||
1277 xy.redy == PNG_FIXED_ERROR ||
1278 xy.greenx == PNG_FIXED_ERROR ||
1279 xy.greeny == PNG_FIXED_ERROR ||
1280 xy.bluex == PNG_FIXED_ERROR ||
1281 xy.bluey == PNG_FIXED_ERROR)
1282 {
1283 png_chunk_benign_error(png_ptr, "invalid values");
1284 return;
1285 }
1286
1287 /* If a colorspace error has already been output skip this chunk */
1288 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1289 return;
1290
1291 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0)
1292 {
1293 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1294 png_colorspace_sync(png_ptr, info_ptr);
1295 png_chunk_benign_error(png_ptr, "duplicate");
1296 return;
1297 }
1298
1299 png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
1300 (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1301 1/*prefer cHRM values*/);
1302 png_colorspace_sync(png_ptr, info_ptr);
1303 }
1304 #endif
1305
1306 #ifdef PNG_READ_sRGB_SUPPORTED
1307 void /* PRIVATE */
png_handle_sRGB(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1308 png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1309 {
1310 png_byte intent;
1311
1312 png_debug(1, "in png_handle_sRGB");
1313
1314 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1315 png_chunk_error(png_ptr, "missing IHDR");
1316
1317 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1318 {
1319 png_crc_finish(png_ptr, length);
1320 png_chunk_benign_error(png_ptr, "out of place");
1321 return;
1322 }
1323
1324 if (length != 1)
1325 {
1326 png_crc_finish(png_ptr, length);
1327 png_chunk_benign_error(png_ptr, "invalid");
1328 return;
1329 }
1330
1331 png_crc_read(png_ptr, &intent, 1);
1332
1333 if (png_crc_finish(png_ptr, 0) != 0)
1334 return;
1335
1336 /* If a colorspace error has already been output skip this chunk */
1337 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1338 return;
1339
1340 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1341 * this.
1342 */
1343 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0)
1344 {
1345 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1346 png_colorspace_sync(png_ptr, info_ptr);
1347 png_chunk_benign_error(png_ptr, "too many profiles");
1348 return;
1349 }
1350
1351 (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
1352 png_colorspace_sync(png_ptr, info_ptr);
1353 }
1354 #endif /* READ_sRGB */
1355
1356 #ifdef PNG_READ_iCCP_SUPPORTED
1357 void /* PRIVATE */
png_handle_iCCP(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1358 png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1359 /* Note: this does not properly handle profiles that are > 64K under DOS */
1360 {
1361 png_const_charp errmsg = NULL; /* error message output, or no error */
1362 int finished = 0; /* crc checked */
1363
1364 png_debug(1, "in png_handle_iCCP");
1365
1366 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1367 png_chunk_error(png_ptr, "missing IHDR");
1368
1369 else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
1370 {
1371 png_crc_finish(png_ptr, length);
1372 png_chunk_benign_error(png_ptr, "out of place");
1373 return;
1374 }
1375
1376 /* Consistent with all the above colorspace handling an obviously *invalid*
1377 * chunk is just ignored, so does not invalidate the color space. An
1378 * alternative is to set the 'invalid' flags at the start of this routine
1379 * and only clear them in they were not set before and all the tests pass.
1380 * The minimum 'deflate' stream is assumed to be just the 2 byte header and
1381 * 4 byte checksum. The keyword must be at least one character and there is
1382 * a terminator (0) byte and the compression method.
1383 */
1384 if (length < 9)
1385 {
1386 png_crc_finish(png_ptr, length);
1387 png_chunk_benign_error(png_ptr, "too short");
1388 return;
1389 }
1390
1391 /* If a colorspace error has already been output skip this chunk */
1392 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
1393 {
1394 png_crc_finish(png_ptr, length);
1395 return;
1396 }
1397
1398 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1399 * this.
1400 */
1401 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
1402 {
1403 uInt read_length, keyword_length;
1404 char keyword[81];
1405
1406 /* Find the keyword; the keyword plus separator and compression method
1407 * bytes can be at most 81 characters long.
1408 */
1409 read_length = 81; /* maximum */
1410 if (read_length > length)
1411 read_length = (uInt)length;
1412
1413 png_crc_read(png_ptr, (png_bytep)keyword, read_length);
1414 length -= read_length;
1415
1416 keyword_length = 0;
1417 while (keyword_length < 80 && keyword_length < read_length &&
1418 keyword[keyword_length] != 0)
1419 ++keyword_length;
1420
1421 /* TODO: make the keyword checking common */
1422 if (keyword_length >= 1 && keyword_length <= 79)
1423 {
1424 /* We only understand '0' compression - deflate - so if we get a
1425 * different value we can't safely decode the chunk.
1426 */
1427 if (keyword_length+1 < read_length &&
1428 keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
1429 {
1430 read_length -= keyword_length+2;
1431
1432 if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
1433 {
1434 Byte profile_header[132];
1435 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
1436 png_alloc_size_t size = (sizeof profile_header);
1437
1438 png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
1439 png_ptr->zstream.avail_in = read_length;
1440 (void)png_inflate_read(png_ptr, local_buffer,
1441 (sizeof local_buffer), &length, profile_header, &size,
1442 0/*finish: don't, because the output is too small*/);
1443
1444 if (size == 0)
1445 {
1446 /* We have the ICC profile header; do the basic header checks.
1447 */
1448 const png_uint_32 profile_length =
1449 png_get_uint_32(profile_header);
1450
1451 if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
1452 keyword, profile_length) != 0)
1453 {
1454 /* The length is apparently ok, so we can check the 132
1455 * byte header.
1456 */
1457 if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
1458 keyword, profile_length, profile_header,
1459 png_ptr->color_type) != 0)
1460 {
1461 /* Now read the tag table; a variable size buffer is
1462 * needed at this point, allocate one for the whole
1463 * profile. The header check has already validated
1464 * that none of these stuff will overflow.
1465 */
1466 const png_uint_32 tag_count = png_get_uint_32(
1467 profile_header+128);
1468 png_bytep profile = png_read_buffer(png_ptr,
1469 profile_length, 2/*silent*/);
1470
1471 if (profile != NULL)
1472 {
1473 memcpy(profile, profile_header,
1474 (sizeof profile_header));
1475
1476 size = 12 * tag_count;
1477
1478 (void)png_inflate_read(png_ptr, local_buffer,
1479 (sizeof local_buffer), &length,
1480 profile + (sizeof profile_header), &size, 0);
1481
1482 /* Still expect a buffer error because we expect
1483 * there to be some tag data!
1484 */
1485 if (size == 0)
1486 {
1487 if (png_icc_check_tag_table(png_ptr,
1488 &png_ptr->colorspace, keyword, profile_length,
1489 profile) != 0)
1490 {
1491 /* The profile has been validated for basic
1492 * security issues, so read the whole thing in.
1493 */
1494 size = profile_length - (sizeof profile_header)
1495 - 12 * tag_count;
1496
1497 (void)png_inflate_read(png_ptr, local_buffer,
1498 (sizeof local_buffer), &length,
1499 profile + (sizeof profile_header) +
1500 12 * tag_count, &size, 1/*finish*/);
1501
1502 if (length > 0 && !(png_ptr->flags &
1503 PNG_FLAG_BENIGN_ERRORS_WARN))
1504 errmsg = "extra compressed data";
1505
1506 /* But otherwise allow extra data: */
1507 else if (size == 0)
1508 {
1509 if (length > 0)
1510 {
1511 /* This can be handled completely, so
1512 * keep going.
1513 */
1514 png_chunk_warning(png_ptr,
1515 "extra compressed data");
1516 }
1517
1518 png_crc_finish(png_ptr, length);
1519 finished = 1;
1520
1521 # if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
1522 /* Check for a match against sRGB */
1523 png_icc_set_sRGB(png_ptr,
1524 &png_ptr->colorspace, profile,
1525 png_ptr->zstream.adler);
1526 # endif
1527
1528 /* Steal the profile for info_ptr. */
1529 if (info_ptr != NULL)
1530 {
1531 png_free_data(png_ptr, info_ptr,
1532 PNG_FREE_ICCP, 0);
1533
1534 info_ptr->iccp_name = png_voidcast(char*,
1535 png_malloc_base(png_ptr,
1536 keyword_length+1));
1537 if (info_ptr->iccp_name != NULL)
1538 {
1539 memcpy(info_ptr->iccp_name, keyword,
1540 keyword_length+1);
1541 info_ptr->iccp_proflen =
1542 profile_length;
1543 info_ptr->iccp_profile = profile;
1544 png_ptr->read_buffer = NULL; /*steal*/
1545 info_ptr->free_me |= PNG_FREE_ICCP;
1546 info_ptr->valid |= PNG_INFO_iCCP;
1547 }
1548
1549 else
1550 {
1551 png_ptr->colorspace.flags |=
1552 PNG_COLORSPACE_INVALID;
1553 errmsg = "out of memory";
1554 }
1555 }
1556
1557 /* else the profile remains in the read
1558 * buffer which gets reused for subsequent
1559 * chunks.
1560 */
1561
1562 if (info_ptr != NULL)
1563 png_colorspace_sync(png_ptr, info_ptr);
1564
1565 if (errmsg == NULL)
1566 {
1567 png_ptr->zowner = 0;
1568 return;
1569 }
1570 }
1571
1572 else if (size > 0)
1573 errmsg = "truncated";
1574
1575 #ifndef __COVERITY__
1576 else
1577 errmsg = png_ptr->zstream.msg;
1578 #endif
1579 }
1580
1581 /* else png_icc_check_tag_table output an error */
1582 }
1583
1584 else /* profile truncated */
1585 errmsg = png_ptr->zstream.msg;
1586 }
1587
1588 else
1589 errmsg = "out of memory";
1590 }
1591
1592 /* else png_icc_check_header output an error */
1593 }
1594
1595 /* else png_icc_check_length output an error */
1596 }
1597
1598 else /* profile truncated */
1599 errmsg = png_ptr->zstream.msg;
1600
1601 /* Release the stream */
1602 png_ptr->zowner = 0;
1603 }
1604
1605 else /* png_inflate_claim failed */
1606 errmsg = png_ptr->zstream.msg;
1607 }
1608
1609 else
1610 errmsg = "bad compression method"; /* or missing */
1611 }
1612
1613 else
1614 errmsg = "bad keyword";
1615 }
1616
1617 else
1618 errmsg = "too many profiles";
1619
1620 /* Failure: the reason is in 'errmsg' */
1621 if (finished == 0)
1622 png_crc_finish(png_ptr, length);
1623
1624 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1625 png_colorspace_sync(png_ptr, info_ptr);
1626 if (errmsg != NULL) /* else already output */
1627 png_chunk_benign_error(png_ptr, errmsg);
1628 }
1629 #endif /* READ_iCCP */
1630
1631 #ifdef PNG_READ_sPLT_SUPPORTED
1632 void /* PRIVATE */
png_handle_sPLT(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1633 png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1634 /* Note: this does not properly handle chunks that are > 64K under DOS */
1635 {
1636 png_bytep entry_start, buffer;
1637 png_sPLT_t new_palette;
1638 png_sPLT_entryp pp;
1639 png_uint_32 data_length;
1640 int entry_size, i;
1641 png_uint_32 skip = 0;
1642 png_uint_32 dl;
1643 png_size_t max_dl;
1644
1645 png_debug(1, "in png_handle_sPLT");
1646
1647 #ifdef PNG_USER_LIMITS_SUPPORTED
1648 if (png_ptr->user_chunk_cache_max != 0)
1649 {
1650 if (png_ptr->user_chunk_cache_max == 1)
1651 {
1652 png_crc_finish(png_ptr, length);
1653 return;
1654 }
1655
1656 if (--png_ptr->user_chunk_cache_max == 1)
1657 {
1658 png_warning(png_ptr, "No space in chunk cache for sPLT");
1659 png_crc_finish(png_ptr, length);
1660 return;
1661 }
1662 }
1663 #endif
1664
1665 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1666 png_chunk_error(png_ptr, "missing IHDR");
1667
1668 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
1669 {
1670 png_crc_finish(png_ptr, length);
1671 png_chunk_benign_error(png_ptr, "out of place");
1672 return;
1673 }
1674
1675 #ifdef PNG_MAX_MALLOC_64K
1676 if (length > 65535U)
1677 {
1678 png_crc_finish(png_ptr, length);
1679 png_chunk_benign_error(png_ptr, "too large to fit in memory");
1680 return;
1681 }
1682 #endif
1683
1684 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
1685 if (buffer == NULL)
1686 {
1687 png_crc_finish(png_ptr, length);
1688 png_chunk_benign_error(png_ptr, "out of memory");
1689 return;
1690 }
1691
1692
1693 /* WARNING: this may break if size_t is less than 32 bits; it is assumed
1694 * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
1695 * potential breakage point if the types in pngconf.h aren't exactly right.
1696 */
1697 png_crc_read(png_ptr, buffer, length);
1698
1699 if (png_crc_finish(png_ptr, skip) != 0)
1700 return;
1701
1702 buffer[length] = 0;
1703
1704 for (entry_start = buffer; *entry_start; entry_start++)
1705 /* Empty loop to find end of name */ ;
1706
1707 ++entry_start;
1708
1709 /* A sample depth should follow the separator, and we should be on it */
1710 if (length < 2U || entry_start > buffer + (length - 2U))
1711 {
1712 png_warning(png_ptr, "malformed sPLT chunk");
1713 return;
1714 }
1715
1716 new_palette.depth = *entry_start++;
1717 entry_size = (new_palette.depth == 8 ? 6 : 10);
1718 /* This must fit in a png_uint_32 because it is derived from the original
1719 * chunk data length.
1720 */
1721 data_length = length - (png_uint_32)(entry_start - buffer);
1722
1723 /* Integrity-check the data length */
1724 if ((data_length % (unsigned int)entry_size) != 0)
1725 {
1726 png_warning(png_ptr, "sPLT chunk has bad length");
1727 return;
1728 }
1729
1730 dl = (png_uint_32)(data_length / (unsigned int)entry_size);
1731 max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
1732
1733 if (dl > max_dl)
1734 {
1735 png_warning(png_ptr, "sPLT chunk too long");
1736 return;
1737 }
1738
1739 new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size);
1740
1741 new_palette.entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
1742 (png_alloc_size_t) new_palette.nentries * (sizeof (png_sPLT_entry)));
1743
1744 if (new_palette.entries == NULL)
1745 {
1746 png_warning(png_ptr, "sPLT chunk requires too much memory");
1747 return;
1748 }
1749
1750 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1751 for (i = 0; i < new_palette.nentries; i++)
1752 {
1753 pp = new_palette.entries + i;
1754
1755 if (new_palette.depth == 8)
1756 {
1757 pp->red = *entry_start++;
1758 pp->green = *entry_start++;
1759 pp->blue = *entry_start++;
1760 pp->alpha = *entry_start++;
1761 }
1762
1763 else
1764 {
1765 pp->red = png_get_uint_16(entry_start); entry_start += 2;
1766 pp->green = png_get_uint_16(entry_start); entry_start += 2;
1767 pp->blue = png_get_uint_16(entry_start); entry_start += 2;
1768 pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
1769 }
1770
1771 pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
1772 }
1773 #else
1774 pp = new_palette.entries;
1775
1776 for (i = 0; i < new_palette.nentries; i++)
1777 {
1778
1779 if (new_palette.depth == 8)
1780 {
1781 pp[i].red = *entry_start++;
1782 pp[i].green = *entry_start++;
1783 pp[i].blue = *entry_start++;
1784 pp[i].alpha = *entry_start++;
1785 }
1786
1787 else
1788 {
1789 pp[i].red = png_get_uint_16(entry_start); entry_start += 2;
1790 pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
1791 pp[i].blue = png_get_uint_16(entry_start); entry_start += 2;
1792 pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
1793 }
1794
1795 pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
1796 }
1797 #endif
1798
1799 /* Discard all chunk data except the name and stash that */
1800 new_palette.name = (png_charp)buffer;
1801
1802 png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
1803
1804 png_free(png_ptr, new_palette.entries);
1805 }
1806 #endif /* READ_sPLT */
1807
1808 #ifdef PNG_READ_tRNS_SUPPORTED
1809 void /* PRIVATE */
png_handle_tRNS(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1810 png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1811 {
1812 png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
1813
1814 png_debug(1, "in png_handle_tRNS");
1815
1816 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1817 png_chunk_error(png_ptr, "missing IHDR");
1818
1819 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
1820 {
1821 png_crc_finish(png_ptr, length);
1822 png_chunk_benign_error(png_ptr, "out of place");
1823 return;
1824 }
1825
1826 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)
1827 {
1828 png_crc_finish(png_ptr, length);
1829 png_chunk_benign_error(png_ptr, "duplicate");
1830 return;
1831 }
1832
1833 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
1834 {
1835 png_byte buf[2];
1836
1837 if (length != 2)
1838 {
1839 png_crc_finish(png_ptr, length);
1840 png_chunk_benign_error(png_ptr, "invalid");
1841 return;
1842 }
1843
1844 png_crc_read(png_ptr, buf, 2);
1845 png_ptr->num_trans = 1;
1846 png_ptr->trans_color.gray = png_get_uint_16(buf);
1847 }
1848
1849 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
1850 {
1851 png_byte buf[6];
1852
1853 if (length != 6)
1854 {
1855 png_crc_finish(png_ptr, length);
1856 png_chunk_benign_error(png_ptr, "invalid");
1857 return;
1858 }
1859
1860 png_crc_read(png_ptr, buf, length);
1861 png_ptr->num_trans = 1;
1862 png_ptr->trans_color.red = png_get_uint_16(buf);
1863 png_ptr->trans_color.green = png_get_uint_16(buf + 2);
1864 png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
1865 }
1866
1867 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1868 {
1869 if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
1870 {
1871 /* TODO: is this actually an error in the ISO spec? */
1872 png_crc_finish(png_ptr, length);
1873 png_chunk_benign_error(png_ptr, "out of place");
1874 return;
1875 }
1876
1877 if (length > (unsigned int) png_ptr->num_palette ||
1878 length > (unsigned int) PNG_MAX_PALETTE_LENGTH ||
1879 length == 0)
1880 {
1881 png_crc_finish(png_ptr, length);
1882 png_chunk_benign_error(png_ptr, "invalid");
1883 return;
1884 }
1885
1886 png_crc_read(png_ptr, readbuf, length);
1887 png_ptr->num_trans = (png_uint_16)length;
1888 }
1889
1890 else
1891 {
1892 png_crc_finish(png_ptr, length);
1893 png_chunk_benign_error(png_ptr, "invalid with alpha channel");
1894 return;
1895 }
1896
1897 if (png_crc_finish(png_ptr, 0) != 0)
1898 {
1899 png_ptr->num_trans = 0;
1900 return;
1901 }
1902
1903 /* TODO: this is a horrible side effect in the palette case because the
1904 * png_struct ends up with a pointer to the tRNS buffer owned by the
1905 * png_info. Fix this.
1906 */
1907 png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
1908 &(png_ptr->trans_color));
1909 }
1910 #endif
1911
1912 #ifdef PNG_READ_bKGD_SUPPORTED
1913 void /* PRIVATE */
png_handle_bKGD(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)1914 png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1915 {
1916 unsigned int truelen;
1917 png_byte buf[6];
1918 png_color_16 background;
1919
1920 png_debug(1, "in png_handle_bKGD");
1921
1922 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
1923 png_chunk_error(png_ptr, "missing IHDR");
1924
1925 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
1926 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
1927 (png_ptr->mode & PNG_HAVE_PLTE) == 0))
1928 {
1929 png_crc_finish(png_ptr, length);
1930 png_chunk_benign_error(png_ptr, "out of place");
1931 return;
1932 }
1933
1934 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1935 {
1936 png_crc_finish(png_ptr, length);
1937 png_chunk_benign_error(png_ptr, "duplicate");
1938 return;
1939 }
1940
1941 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1942 truelen = 1;
1943
1944 else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1945 truelen = 6;
1946
1947 else
1948 truelen = 2;
1949
1950 if (length != truelen)
1951 {
1952 png_crc_finish(png_ptr, length);
1953 png_chunk_benign_error(png_ptr, "invalid");
1954 return;
1955 }
1956
1957 png_crc_read(png_ptr, buf, truelen);
1958
1959 if (png_crc_finish(png_ptr, 0) != 0)
1960 return;
1961
1962 /* We convert the index value into RGB components so that we can allow
1963 * arbitrary RGB values for background when we have transparency, and
1964 * so it is easy to determine the RGB values of the background color
1965 * from the info_ptr struct.
1966 */
1967 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1968 {
1969 background.index = buf[0];
1970
1971 if (info_ptr != NULL && info_ptr->num_palette != 0)
1972 {
1973 if (buf[0] >= info_ptr->num_palette)
1974 {
1975 png_chunk_benign_error(png_ptr, "invalid index");
1976 return;
1977 }
1978
1979 background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
1980 background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
1981 background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
1982 }
1983
1984 else
1985 background.red = background.green = background.blue = 0;
1986
1987 background.gray = 0;
1988 }
1989
1990 else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
1991 {
1992 background.index = 0;
1993 background.red =
1994 background.green =
1995 background.blue =
1996 background.gray = png_get_uint_16(buf);
1997 }
1998
1999 else
2000 {
2001 background.index = 0;
2002 background.red = png_get_uint_16(buf);
2003 background.green = png_get_uint_16(buf + 2);
2004 background.blue = png_get_uint_16(buf + 4);
2005 background.gray = 0;
2006 }
2007
2008 png_set_bKGD(png_ptr, info_ptr, &background);
2009 }
2010 #endif
2011
2012 #ifdef PNG_READ_hIST_SUPPORTED
2013 void /* PRIVATE */
png_handle_hIST(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2014 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2015 {
2016 unsigned int num, i;
2017 png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
2018
2019 png_debug(1, "in png_handle_hIST");
2020
2021 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2022 png_chunk_error(png_ptr, "missing IHDR");
2023
2024 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
2025 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
2026 {
2027 png_crc_finish(png_ptr, length);
2028 png_chunk_benign_error(png_ptr, "out of place");
2029 return;
2030 }
2031
2032 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
2033 {
2034 png_crc_finish(png_ptr, length);
2035 png_chunk_benign_error(png_ptr, "duplicate");
2036 return;
2037 }
2038
2039 num = length / 2 ;
2040
2041 if (num != (unsigned int) png_ptr->num_palette ||
2042 num > (unsigned int) PNG_MAX_PALETTE_LENGTH)
2043 {
2044 png_crc_finish(png_ptr, length);
2045 png_chunk_benign_error(png_ptr, "invalid");
2046 return;
2047 }
2048
2049 for (i = 0; i < num; i++)
2050 {
2051 png_byte buf[2];
2052
2053 png_crc_read(png_ptr, buf, 2);
2054 readbuf[i] = png_get_uint_16(buf);
2055 }
2056
2057 if (png_crc_finish(png_ptr, 0) != 0)
2058 return;
2059
2060 png_set_hIST(png_ptr, info_ptr, readbuf);
2061 }
2062 #endif
2063
2064 #ifdef PNG_READ_pHYs_SUPPORTED
2065 void /* PRIVATE */
png_handle_pHYs(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2066 png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2067 {
2068 png_byte buf[9];
2069 png_uint_32 res_x, res_y;
2070 int unit_type;
2071
2072 png_debug(1, "in png_handle_pHYs");
2073
2074 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2075 png_chunk_error(png_ptr, "missing IHDR");
2076
2077 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2078 {
2079 png_crc_finish(png_ptr, length);
2080 png_chunk_benign_error(png_ptr, "out of place");
2081 return;
2082 }
2083
2084 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs) != 0)
2085 {
2086 png_crc_finish(png_ptr, length);
2087 png_chunk_benign_error(png_ptr, "duplicate");
2088 return;
2089 }
2090
2091 if (length != 9)
2092 {
2093 png_crc_finish(png_ptr, length);
2094 png_chunk_benign_error(png_ptr, "invalid");
2095 return;
2096 }
2097
2098 png_crc_read(png_ptr, buf, 9);
2099
2100 if (png_crc_finish(png_ptr, 0) != 0)
2101 return;
2102
2103 res_x = png_get_uint_32(buf);
2104 res_y = png_get_uint_32(buf + 4);
2105 unit_type = buf[8];
2106 png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
2107 }
2108 #endif
2109
2110 #ifdef PNG_READ_oFFs_SUPPORTED
2111 void /* PRIVATE */
png_handle_oFFs(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2112 png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2113 {
2114 png_byte buf[9];
2115 png_int_32 offset_x, offset_y;
2116 int unit_type;
2117
2118 png_debug(1, "in png_handle_oFFs");
2119
2120 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2121 png_chunk_error(png_ptr, "missing IHDR");
2122
2123 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2124 {
2125 png_crc_finish(png_ptr, length);
2126 png_chunk_benign_error(png_ptr, "out of place");
2127 return;
2128 }
2129
2130 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs) != 0)
2131 {
2132 png_crc_finish(png_ptr, length);
2133 png_chunk_benign_error(png_ptr, "duplicate");
2134 return;
2135 }
2136
2137 if (length != 9)
2138 {
2139 png_crc_finish(png_ptr, length);
2140 png_chunk_benign_error(png_ptr, "invalid");
2141 return;
2142 }
2143
2144 png_crc_read(png_ptr, buf, 9);
2145
2146 if (png_crc_finish(png_ptr, 0) != 0)
2147 return;
2148
2149 offset_x = png_get_int_32(buf);
2150 offset_y = png_get_int_32(buf + 4);
2151 unit_type = buf[8];
2152 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
2153 }
2154 #endif
2155
2156 #ifdef PNG_READ_pCAL_SUPPORTED
2157 /* Read the pCAL chunk (described in the PNG Extensions document) */
2158 void /* PRIVATE */
png_handle_pCAL(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2159 png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2160 {
2161 png_int_32 X0, X1;
2162 png_byte type, nparams;
2163 png_bytep buffer, buf, units, endptr;
2164 png_charpp params;
2165 int i;
2166
2167 png_debug(1, "in png_handle_pCAL");
2168
2169 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2170 png_chunk_error(png_ptr, "missing IHDR");
2171
2172 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2173 {
2174 png_crc_finish(png_ptr, length);
2175 png_chunk_benign_error(png_ptr, "out of place");
2176 return;
2177 }
2178
2179 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL) != 0)
2180 {
2181 png_crc_finish(png_ptr, length);
2182 png_chunk_benign_error(png_ptr, "duplicate");
2183 return;
2184 }
2185
2186 png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
2187 length + 1);
2188
2189 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2190
2191 if (buffer == NULL)
2192 {
2193 png_crc_finish(png_ptr, length);
2194 png_chunk_benign_error(png_ptr, "out of memory");
2195 return;
2196 }
2197
2198 png_crc_read(png_ptr, buffer, length);
2199
2200 if (png_crc_finish(png_ptr, 0) != 0)
2201 return;
2202
2203 buffer[length] = 0; /* Null terminate the last string */
2204
2205 png_debug(3, "Finding end of pCAL purpose string");
2206 for (buf = buffer; *buf; buf++)
2207 /* Empty loop */ ;
2208
2209 endptr = buffer + length;
2210
2211 /* We need to have at least 12 bytes after the purpose string
2212 * in order to get the parameter information.
2213 */
2214 if (endptr - buf <= 12)
2215 {
2216 png_chunk_benign_error(png_ptr, "invalid");
2217 return;
2218 }
2219
2220 png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
2221 X0 = png_get_int_32((png_bytep)buf+1);
2222 X1 = png_get_int_32((png_bytep)buf+5);
2223 type = buf[9];
2224 nparams = buf[10];
2225 units = buf + 11;
2226
2227 png_debug(3, "Checking pCAL equation type and number of parameters");
2228 /* Check that we have the right number of parameters for known
2229 * equation types.
2230 */
2231 if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
2232 (type == PNG_EQUATION_BASE_E && nparams != 3) ||
2233 (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
2234 (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
2235 {
2236 png_chunk_benign_error(png_ptr, "invalid parameter count");
2237 return;
2238 }
2239
2240 else if (type >= PNG_EQUATION_LAST)
2241 {
2242 png_chunk_benign_error(png_ptr, "unrecognized equation type");
2243 }
2244
2245 for (buf = units; *buf; buf++)
2246 /* Empty loop to move past the units string. */ ;
2247
2248 png_debug(3, "Allocating pCAL parameters array");
2249
2250 params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
2251 nparams * (sizeof (png_charp))));
2252
2253 if (params == NULL)
2254 {
2255 png_chunk_benign_error(png_ptr, "out of memory");
2256 return;
2257 }
2258
2259 /* Get pointers to the start of each parameter string. */
2260 for (i = 0; i < nparams; i++)
2261 {
2262 buf++; /* Skip the null string terminator from previous parameter. */
2263
2264 png_debug1(3, "Reading pCAL parameter %d", i);
2265
2266 for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
2267 /* Empty loop to move past each parameter string */ ;
2268
2269 /* Make sure we haven't run out of data yet */
2270 if (buf > endptr)
2271 {
2272 png_free(png_ptr, params);
2273 png_chunk_benign_error(png_ptr, "invalid data");
2274 return;
2275 }
2276 }
2277
2278 png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
2279 (png_charp)units, params);
2280
2281 png_free(png_ptr, params);
2282 }
2283 #endif
2284
2285 #ifdef PNG_READ_sCAL_SUPPORTED
2286 /* Read the sCAL chunk */
2287 void /* PRIVATE */
png_handle_sCAL(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2288 png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2289 {
2290 png_bytep buffer;
2291 png_size_t i;
2292 int state;
2293
2294 png_debug(1, "in png_handle_sCAL");
2295
2296 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2297 png_chunk_error(png_ptr, "missing IHDR");
2298
2299 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2300 {
2301 png_crc_finish(png_ptr, length);
2302 png_chunk_benign_error(png_ptr, "out of place");
2303 return;
2304 }
2305
2306 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL) != 0)
2307 {
2308 png_crc_finish(png_ptr, length);
2309 png_chunk_benign_error(png_ptr, "duplicate");
2310 return;
2311 }
2312
2313 /* Need unit type, width, \0, height: minimum 4 bytes */
2314 else if (length < 4)
2315 {
2316 png_crc_finish(png_ptr, length);
2317 png_chunk_benign_error(png_ptr, "invalid");
2318 return;
2319 }
2320
2321 png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
2322 length + 1);
2323
2324 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2325
2326 if (buffer == NULL)
2327 {
2328 png_chunk_benign_error(png_ptr, "out of memory");
2329 png_crc_finish(png_ptr, length);
2330 return;
2331 }
2332
2333 png_crc_read(png_ptr, buffer, length);
2334 buffer[length] = 0; /* Null terminate the last string */
2335
2336 if (png_crc_finish(png_ptr, 0) != 0)
2337 return;
2338
2339 /* Validate the unit. */
2340 if (buffer[0] != 1 && buffer[0] != 2)
2341 {
2342 png_chunk_benign_error(png_ptr, "invalid unit");
2343 return;
2344 }
2345
2346 /* Validate the ASCII numbers, need two ASCII numbers separated by
2347 * a '\0' and they need to fit exactly in the chunk data.
2348 */
2349 i = 1;
2350 state = 0;
2351
2352 if (png_check_fp_number((png_const_charp)buffer, length, &state, &i) == 0 ||
2353 i >= length || buffer[i++] != 0)
2354 png_chunk_benign_error(png_ptr, "bad width format");
2355
2356 else if (PNG_FP_IS_POSITIVE(state) == 0)
2357 png_chunk_benign_error(png_ptr, "non-positive width");
2358
2359 else
2360 {
2361 png_size_t heighti = i;
2362
2363 state = 0;
2364 if (png_check_fp_number((png_const_charp)buffer, length,
2365 &state, &i) == 0 || i != length)
2366 png_chunk_benign_error(png_ptr, "bad height format");
2367
2368 else if (PNG_FP_IS_POSITIVE(state) == 0)
2369 png_chunk_benign_error(png_ptr, "non-positive height");
2370
2371 else
2372 /* This is the (only) success case. */
2373 png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
2374 (png_charp)buffer+1, (png_charp)buffer+heighti);
2375 }
2376 }
2377 #endif
2378
2379 #ifdef PNG_READ_tIME_SUPPORTED
2380 void /* PRIVATE */
png_handle_tIME(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2381 png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2382 {
2383 png_byte buf[7];
2384 png_time mod_time;
2385
2386 png_debug(1, "in png_handle_tIME");
2387
2388 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2389 png_chunk_error(png_ptr, "missing IHDR");
2390
2391 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME) != 0)
2392 {
2393 png_crc_finish(png_ptr, length);
2394 png_chunk_benign_error(png_ptr, "duplicate");
2395 return;
2396 }
2397
2398 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2399 png_ptr->mode |= PNG_AFTER_IDAT;
2400
2401 if (length != 7)
2402 {
2403 png_crc_finish(png_ptr, length);
2404 png_chunk_benign_error(png_ptr, "invalid");
2405 return;
2406 }
2407
2408 png_crc_read(png_ptr, buf, 7);
2409
2410 if (png_crc_finish(png_ptr, 0) != 0)
2411 return;
2412
2413 mod_time.second = buf[6];
2414 mod_time.minute = buf[5];
2415 mod_time.hour = buf[4];
2416 mod_time.day = buf[3];
2417 mod_time.month = buf[2];
2418 mod_time.year = png_get_uint_16(buf);
2419
2420 png_set_tIME(png_ptr, info_ptr, &mod_time);
2421 }
2422 #endif
2423
2424 #ifdef PNG_READ_tEXt_SUPPORTED
2425 /* Note: this does not properly handle chunks that are > 64K under DOS */
2426 void /* PRIVATE */
png_handle_tEXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2427 png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2428 {
2429 png_text text_info;
2430 png_bytep buffer;
2431 png_charp key;
2432 png_charp text;
2433 png_uint_32 skip = 0;
2434
2435 png_debug(1, "in png_handle_tEXt");
2436
2437 #ifdef PNG_USER_LIMITS_SUPPORTED
2438 if (png_ptr->user_chunk_cache_max != 0)
2439 {
2440 if (png_ptr->user_chunk_cache_max == 1)
2441 {
2442 png_crc_finish(png_ptr, length);
2443 return;
2444 }
2445
2446 if (--png_ptr->user_chunk_cache_max == 1)
2447 {
2448 png_crc_finish(png_ptr, length);
2449 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2450 return;
2451 }
2452 }
2453 #endif
2454
2455 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2456 png_chunk_error(png_ptr, "missing IHDR");
2457
2458 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2459 png_ptr->mode |= PNG_AFTER_IDAT;
2460
2461 #ifdef PNG_MAX_MALLOC_64K
2462 if (length > 65535U)
2463 {
2464 png_crc_finish(png_ptr, length);
2465 png_chunk_benign_error(png_ptr, "too large to fit in memory");
2466 return;
2467 }
2468 #endif
2469
2470 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2471
2472 if (buffer == NULL)
2473 {
2474 png_chunk_benign_error(png_ptr, "out of memory");
2475 return;
2476 }
2477
2478 png_crc_read(png_ptr, buffer, length);
2479
2480 if (png_crc_finish(png_ptr, skip) != 0)
2481 return;
2482
2483 key = (png_charp)buffer;
2484 key[length] = 0;
2485
2486 for (text = key; *text; text++)
2487 /* Empty loop to find end of key */ ;
2488
2489 if (text != key + length)
2490 text++;
2491
2492 text_info.compression = PNG_TEXT_COMPRESSION_NONE;
2493 text_info.key = key;
2494 text_info.lang = NULL;
2495 text_info.lang_key = NULL;
2496 text_info.itxt_length = 0;
2497 text_info.text = text;
2498 text_info.text_length = strlen(text);
2499
2500 if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) != 0)
2501 png_warning(png_ptr, "Insufficient memory to process text chunk");
2502 }
2503 #endif
2504
2505 #ifdef PNG_READ_zTXt_SUPPORTED
2506 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2507 void /* PRIVATE */
png_handle_zTXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2508 png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2509 {
2510 png_const_charp errmsg = NULL;
2511 png_bytep buffer;
2512 png_uint_32 keyword_length;
2513
2514 png_debug(1, "in png_handle_zTXt");
2515
2516 #ifdef PNG_USER_LIMITS_SUPPORTED
2517 if (png_ptr->user_chunk_cache_max != 0)
2518 {
2519 if (png_ptr->user_chunk_cache_max == 1)
2520 {
2521 png_crc_finish(png_ptr, length);
2522 return;
2523 }
2524
2525 if (--png_ptr->user_chunk_cache_max == 1)
2526 {
2527 png_crc_finish(png_ptr, length);
2528 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2529 return;
2530 }
2531 }
2532 #endif
2533
2534 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2535 png_chunk_error(png_ptr, "missing IHDR");
2536
2537 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2538 png_ptr->mode |= PNG_AFTER_IDAT;
2539
2540 buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
2541
2542 if (buffer == NULL)
2543 {
2544 png_crc_finish(png_ptr, length);
2545 png_chunk_benign_error(png_ptr, "out of memory");
2546 return;
2547 }
2548
2549 png_crc_read(png_ptr, buffer, length);
2550
2551 if (png_crc_finish(png_ptr, 0) != 0)
2552 return;
2553
2554 /* TODO: also check that the keyword contents match the spec! */
2555 for (keyword_length = 0;
2556 keyword_length < length && buffer[keyword_length] != 0;
2557 ++keyword_length)
2558 /* Empty loop to find end of name */ ;
2559
2560 if (keyword_length > 79 || keyword_length < 1)
2561 errmsg = "bad keyword";
2562
2563 /* zTXt must have some LZ data after the keyword, although it may expand to
2564 * zero bytes; we need a '\0' at the end of the keyword, the compression type
2565 * then the LZ data:
2566 */
2567 else if (keyword_length + 3 > length)
2568 errmsg = "truncated";
2569
2570 else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
2571 errmsg = "unknown compression type";
2572
2573 else
2574 {
2575 png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
2576
2577 /* TODO: at present png_decompress_chunk imposes a single application
2578 * level memory limit, this should be split to different values for iCCP
2579 * and text chunks.
2580 */
2581 if (png_decompress_chunk(png_ptr, length, keyword_length+2,
2582 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2583 {
2584 png_text text;
2585
2586 /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
2587 * for the extra compression type byte and the fact that it isn't
2588 * necessarily '\0' terminated.
2589 */
2590 buffer = png_ptr->read_buffer;
2591 buffer[uncompressed_length+(keyword_length+2)] = 0;
2592
2593 text.compression = PNG_TEXT_COMPRESSION_zTXt;
2594 text.key = (png_charp)buffer;
2595 text.text = (png_charp)(buffer + keyword_length+2);
2596 text.text_length = uncompressed_length;
2597 text.itxt_length = 0;
2598 text.lang = NULL;
2599 text.lang_key = NULL;
2600
2601 if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
2602 errmsg = "insufficient memory";
2603 }
2604
2605 else
2606 errmsg = png_ptr->zstream.msg;
2607 }
2608
2609 if (errmsg != NULL)
2610 png_chunk_benign_error(png_ptr, errmsg);
2611 }
2612 #endif
2613
2614 #ifdef PNG_READ_iTXt_SUPPORTED
2615 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2616 void /* PRIVATE */
png_handle_iTXt(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length)2617 png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2618 {
2619 png_const_charp errmsg = NULL;
2620 png_bytep buffer;
2621 png_uint_32 prefix_length;
2622
2623 png_debug(1, "in png_handle_iTXt");
2624
2625 #ifdef PNG_USER_LIMITS_SUPPORTED
2626 if (png_ptr->user_chunk_cache_max != 0)
2627 {
2628 if (png_ptr->user_chunk_cache_max == 1)
2629 {
2630 png_crc_finish(png_ptr, length);
2631 return;
2632 }
2633
2634 if (--png_ptr->user_chunk_cache_max == 1)
2635 {
2636 png_crc_finish(png_ptr, length);
2637 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2638 return;
2639 }
2640 }
2641 #endif
2642
2643 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
2644 png_chunk_error(png_ptr, "missing IHDR");
2645
2646 if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
2647 png_ptr->mode |= PNG_AFTER_IDAT;
2648
2649 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2650
2651 if (buffer == NULL)
2652 {
2653 png_crc_finish(png_ptr, length);
2654 png_chunk_benign_error(png_ptr, "out of memory");
2655 return;
2656 }
2657
2658 png_crc_read(png_ptr, buffer, length);
2659
2660 if (png_crc_finish(png_ptr, 0) != 0)
2661 return;
2662
2663 /* First the keyword. */
2664 for (prefix_length=0;
2665 prefix_length < length && buffer[prefix_length] != 0;
2666 ++prefix_length)
2667 /* Empty loop */ ;
2668
2669 /* Perform a basic check on the keyword length here. */
2670 if (prefix_length > 79 || prefix_length < 1)
2671 errmsg = "bad keyword";
2672
2673 /* Expect keyword, compression flag, compression type, language, translated
2674 * keyword (both may be empty but are 0 terminated) then the text, which may
2675 * be empty.
2676 */
2677 else if (prefix_length + 5 > length)
2678 errmsg = "truncated";
2679
2680 else if (buffer[prefix_length+1] == 0 ||
2681 (buffer[prefix_length+1] == 1 &&
2682 buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
2683 {
2684 int compressed = buffer[prefix_length+1] != 0;
2685 png_uint_32 language_offset, translated_keyword_offset;
2686 png_alloc_size_t uncompressed_length = 0;
2687
2688 /* Now the language tag */
2689 prefix_length += 3;
2690 language_offset = prefix_length;
2691
2692 for (; prefix_length < length && buffer[prefix_length] != 0;
2693 ++prefix_length)
2694 /* Empty loop */ ;
2695
2696 /* WARNING: the length may be invalid here, this is checked below. */
2697 translated_keyword_offset = ++prefix_length;
2698
2699 for (; prefix_length < length && buffer[prefix_length] != 0;
2700 ++prefix_length)
2701 /* Empty loop */ ;
2702
2703 /* prefix_length should now be at the trailing '\0' of the translated
2704 * keyword, but it may already be over the end. None of this arithmetic
2705 * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
2706 * systems the available allocation may overflow.
2707 */
2708 ++prefix_length;
2709
2710 if (compressed == 0 && prefix_length <= length)
2711 uncompressed_length = length - prefix_length;
2712
2713 else if (compressed != 0 && prefix_length < length)
2714 {
2715 uncompressed_length = PNG_SIZE_MAX;
2716
2717 /* TODO: at present png_decompress_chunk imposes a single application
2718 * level memory limit, this should be split to different values for
2719 * iCCP and text chunks.
2720 */
2721 if (png_decompress_chunk(png_ptr, length, prefix_length,
2722 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2723 buffer = png_ptr->read_buffer;
2724
2725 else
2726 errmsg = png_ptr->zstream.msg;
2727 }
2728
2729 else
2730 errmsg = "truncated";
2731
2732 if (errmsg == NULL)
2733 {
2734 png_text text;
2735
2736 buffer[uncompressed_length+prefix_length] = 0;
2737
2738 if (compressed == 0)
2739 text.compression = PNG_ITXT_COMPRESSION_NONE;
2740
2741 else
2742 text.compression = PNG_ITXT_COMPRESSION_zTXt;
2743
2744 text.key = (png_charp)buffer;
2745 text.lang = (png_charp)buffer + language_offset;
2746 text.lang_key = (png_charp)buffer + translated_keyword_offset;
2747 text.text = (png_charp)buffer + prefix_length;
2748 text.text_length = 0;
2749 text.itxt_length = uncompressed_length;
2750
2751 if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
2752 errmsg = "insufficient memory";
2753 }
2754 }
2755
2756 else
2757 errmsg = "bad compression info";
2758
2759 if (errmsg != NULL)
2760 png_chunk_benign_error(png_ptr, errmsg);
2761 }
2762 #endif
2763
2764 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2765 /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
2766 static int
png_cache_unknown_chunk(png_structrp png_ptr,png_uint_32 length)2767 png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
2768 {
2769 png_alloc_size_t limit = PNG_SIZE_MAX;
2770
2771 if (png_ptr->unknown_chunk.data != NULL)
2772 {
2773 png_free(png_ptr, png_ptr->unknown_chunk.data);
2774 png_ptr->unknown_chunk.data = NULL;
2775 }
2776
2777 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
2778 if (png_ptr->user_chunk_malloc_max > 0 &&
2779 png_ptr->user_chunk_malloc_max < limit)
2780 limit = png_ptr->user_chunk_malloc_max;
2781
2782 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
2783 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
2784 limit = PNG_USER_CHUNK_MALLOC_MAX;
2785 # endif
2786
2787 if (length <= limit)
2788 {
2789 PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
2790 /* The following is safe because of the PNG_SIZE_MAX init above */
2791 png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
2792 /* 'mode' is a flag array, only the bottom four bits matter here */
2793 png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
2794
2795 if (length == 0)
2796 png_ptr->unknown_chunk.data = NULL;
2797
2798 else
2799 {
2800 /* Do a 'warn' here - it is handled below. */
2801 png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
2802 png_malloc_warn(png_ptr, length));
2803 }
2804 }
2805
2806 if (png_ptr->unknown_chunk.data == NULL && length > 0)
2807 {
2808 /* This is benign because we clean up correctly */
2809 png_crc_finish(png_ptr, length);
2810 png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
2811 return 0;
2812 }
2813
2814 else
2815 {
2816 if (length > 0)
2817 png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
2818 png_crc_finish(png_ptr, 0);
2819 return 1;
2820 }
2821 }
2822 #endif /* READ_UNKNOWN_CHUNKS */
2823
2824 /* Handle an unknown, or known but disabled, chunk */
2825 void /* PRIVATE */
png_handle_unknown(png_structrp png_ptr,png_inforp info_ptr,png_uint_32 length,int keep)2826 png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
2827 png_uint_32 length, int keep)
2828 {
2829 int handled = 0; /* the chunk was handled */
2830
2831 png_debug(1, "in png_handle_unknown");
2832
2833 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2834 /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
2835 * the bug which meant that setting a non-default behavior for a specific
2836 * chunk would be ignored (the default was always used unless a user
2837 * callback was installed).
2838 *
2839 * 'keep' is the value from the png_chunk_unknown_handling, the setting for
2840 * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
2841 * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
2842 * This is just an optimization to avoid multiple calls to the lookup
2843 * function.
2844 */
2845 # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
2846 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2847 keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
2848 # endif
2849 # endif
2850
2851 /* One of the following methods will read the chunk or skip it (at least one
2852 * of these is always defined because this is the only way to switch on
2853 * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
2854 */
2855 # ifdef PNG_READ_USER_CHUNKS_SUPPORTED
2856 /* The user callback takes precedence over the chunk keep value, but the
2857 * keep value is still required to validate a save of a critical chunk.
2858 */
2859 if (png_ptr->read_user_chunk_fn != NULL)
2860 {
2861 if (png_cache_unknown_chunk(png_ptr, length) != 0)
2862 {
2863 /* Callback to user unknown chunk handler */
2864 int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
2865 &png_ptr->unknown_chunk);
2866
2867 /* ret is:
2868 * negative: An error occurred; png_chunk_error will be called.
2869 * zero: The chunk was not handled, the chunk will be discarded
2870 * unless png_set_keep_unknown_chunks has been used to set
2871 * a 'keep' behavior for this particular chunk, in which
2872 * case that will be used. A critical chunk will cause an
2873 * error at this point unless it is to be saved.
2874 * positive: The chunk was handled, libpng will ignore/discard it.
2875 */
2876 if (ret < 0)
2877 png_chunk_error(png_ptr, "error in user chunk");
2878
2879 else if (ret == 0)
2880 {
2881 /* If the keep value is 'default' or 'never' override it, but
2882 * still error out on critical chunks unless the keep value is
2883 * 'always' While this is weird it is the behavior in 1.4.12.
2884 * A possible improvement would be to obey the value set for the
2885 * chunk, but this would be an API change that would probably
2886 * damage some applications.
2887 *
2888 * The png_app_warning below catches the case that matters, where
2889 * the application has not set specific save or ignore for this
2890 * chunk or global save or ignore.
2891 */
2892 if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
2893 {
2894 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2895 if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
2896 {
2897 png_chunk_warning(png_ptr, "Saving unknown chunk:");
2898 png_app_warning(png_ptr,
2899 "forcing save of an unhandled chunk;"
2900 " please call png_set_keep_unknown_chunks");
2901 /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
2902 }
2903 # endif
2904 keep = PNG_HANDLE_CHUNK_IF_SAFE;
2905 }
2906 }
2907
2908 else /* chunk was handled */
2909 {
2910 handled = 1;
2911 /* Critical chunks can be safely discarded at this point. */
2912 keep = PNG_HANDLE_CHUNK_NEVER;
2913 }
2914 }
2915
2916 else
2917 keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
2918 }
2919
2920 else
2921 /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
2922 # endif /* READ_USER_CHUNKS */
2923
2924 # ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
2925 {
2926 /* keep is currently just the per-chunk setting, if there was no
2927 * setting change it to the global default now (not that this may
2928 * still be AS_DEFAULT) then obtain the cache of the chunk if required,
2929 * if not simply skip the chunk.
2930 */
2931 if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
2932 keep = png_ptr->unknown_default;
2933
2934 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
2935 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
2936 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
2937 {
2938 if (png_cache_unknown_chunk(png_ptr, length) == 0)
2939 keep = PNG_HANDLE_CHUNK_NEVER;
2940 }
2941
2942 else
2943 png_crc_finish(png_ptr, length);
2944 }
2945 # else
2946 # ifndef PNG_READ_USER_CHUNKS_SUPPORTED
2947 # error no method to support READ_UNKNOWN_CHUNKS
2948 # endif
2949
2950 {
2951 /* If here there is no read callback pointer set and no support is
2952 * compiled in to just save the unknown chunks, so simply skip this
2953 * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then
2954 * the app has erroneously asked for unknown chunk saving when there
2955 * is no support.
2956 */
2957 if (keep > PNG_HANDLE_CHUNK_NEVER)
2958 png_app_error(png_ptr, "no unknown chunk support available");
2959
2960 png_crc_finish(png_ptr, length);
2961 }
2962 # endif
2963
2964 # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2965 /* Now store the chunk in the chunk list if appropriate, and if the limits
2966 * permit it.
2967 */
2968 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
2969 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
2970 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
2971 {
2972 # ifdef PNG_USER_LIMITS_SUPPORTED
2973 switch (png_ptr->user_chunk_cache_max)
2974 {
2975 case 2:
2976 png_ptr->user_chunk_cache_max = 1;
2977 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2978 /* FALL THROUGH */
2979 case 1:
2980 /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
2981 * chunk being skipped, now there will be a hard error below.
2982 */
2983 break;
2984
2985 default: /* not at limit */
2986 --(png_ptr->user_chunk_cache_max);
2987 /* FALL THROUGH */
2988 case 0: /* no limit */
2989 # endif /* USER_LIMITS */
2990 /* Here when the limit isn't reached or when limits are compiled
2991 * out; store the chunk.
2992 */
2993 png_set_unknown_chunks(png_ptr, info_ptr,
2994 &png_ptr->unknown_chunk, 1);
2995 handled = 1;
2996 # ifdef PNG_USER_LIMITS_SUPPORTED
2997 break;
2998 }
2999 # endif
3000 }
3001 # else /* no store support: the chunk must be handled by the user callback */
3002 PNG_UNUSED(info_ptr)
3003 # endif
3004
3005 /* Regardless of the error handling below the cached data (if any) can be
3006 * freed now. Notice that the data is not freed if there is a png_error, but
3007 * it will be freed by destroy_read_struct.
3008 */
3009 if (png_ptr->unknown_chunk.data != NULL)
3010 png_free(png_ptr, png_ptr->unknown_chunk.data);
3011 png_ptr->unknown_chunk.data = NULL;
3012
3013 #else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
3014 /* There is no support to read an unknown chunk, so just skip it. */
3015 png_crc_finish(png_ptr, length);
3016 PNG_UNUSED(info_ptr)
3017 PNG_UNUSED(keep)
3018 #endif /* !READ_UNKNOWN_CHUNKS */
3019
3020 /* Check for unhandled critical chunks */
3021 if (handled == 0 && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
3022 png_chunk_error(png_ptr, "unhandled critical chunk");
3023 }
3024
3025 /* This function is called to verify that a chunk name is valid.
3026 * This function can't have the "critical chunk check" incorporated
3027 * into it, since in the future we will need to be able to call user
3028 * functions to handle unknown critical chunks after we check that
3029 * the chunk name itself is valid.
3030 */
3031
3032 /* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
3033 *
3034 * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
3035 */
3036
3037 void /* PRIVATE */
png_check_chunk_name(png_structrp png_ptr,png_uint_32 chunk_name)3038 png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
3039 {
3040 int i;
3041
3042 png_debug(1, "in png_check_chunk_name");
3043
3044 for (i=1; i<=4; ++i)
3045 {
3046 int c = chunk_name & 0xff;
3047
3048 if (c < 65 || c > 122 || (c > 90 && c < 97))
3049 png_chunk_error(png_ptr, "invalid chunk type");
3050
3051 chunk_name >>= 8;
3052 }
3053 }
3054
3055 /* Combines the row recently read in with the existing pixels in the row. This
3056 * routine takes care of alpha and transparency if requested. This routine also
3057 * handles the two methods of progressive display of interlaced images,
3058 * depending on the 'display' value; if 'display' is true then the whole row
3059 * (dp) is filled from the start by replicating the available pixels. If
3060 * 'display' is false only those pixels present in the pass are filled in.
3061 */
3062 void /* PRIVATE */
png_combine_row(png_const_structrp png_ptr,png_bytep dp,int display)3063 png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
3064 {
3065 unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
3066 png_const_bytep sp = png_ptr->row_buf + 1;
3067 png_alloc_size_t row_width = png_ptr->width;
3068 unsigned int pass = png_ptr->pass;
3069 png_bytep end_ptr = 0;
3070 png_byte end_byte = 0;
3071 unsigned int end_mask;
3072
3073 png_debug(1, "in png_combine_row");
3074
3075 /* Added in 1.5.6: it should not be possible to enter this routine until at
3076 * least one row has been read from the PNG data and transformed.
3077 */
3078 if (pixel_depth == 0)
3079 png_error(png_ptr, "internal row logic error");
3080
3081 /* Added in 1.5.4: the pixel depth should match the information returned by
3082 * any call to png_read_update_info at this point. Do not continue if we got
3083 * this wrong.
3084 */
3085 if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
3086 PNG_ROWBYTES(pixel_depth, row_width))
3087 png_error(png_ptr, "internal row size calculation error");
3088
3089 /* Don't expect this to ever happen: */
3090 if (row_width == 0)
3091 png_error(png_ptr, "internal row width error");
3092
3093 /* Preserve the last byte in cases where only part of it will be overwritten,
3094 * the multiply below may overflow, we don't care because ANSI-C guarantees
3095 * we get the low bits.
3096 */
3097 end_mask = (pixel_depth * row_width) & 7;
3098 if (end_mask != 0)
3099 {
3100 /* end_ptr == NULL is a flag to say do nothing */
3101 end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
3102 end_byte = *end_ptr;
3103 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3104 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
3105 /* little-endian byte */
3106 end_mask = (unsigned int)(0xff << end_mask);
3107
3108 else /* big-endian byte */
3109 # endif
3110 end_mask = 0xff >> end_mask;
3111 /* end_mask is now the bits to *keep* from the destination row */
3112 }
3113
3114 /* For non-interlaced images this reduces to a memcpy(). A memcpy()
3115 * will also happen if interlacing isn't supported or if the application
3116 * does not call png_set_interlace_handling(). In the latter cases the
3117 * caller just gets a sequence of the unexpanded rows from each interlace
3118 * pass.
3119 */
3120 #ifdef PNG_READ_INTERLACING_SUPPORTED
3121 if (png_ptr->interlaced != 0 &&
3122 (png_ptr->transformations & PNG_INTERLACE) != 0 &&
3123 pass < 6 && (display == 0 ||
3124 /* The following copies everything for 'display' on passes 0, 2 and 4. */
3125 (display == 1 && (pass & 1) != 0)))
3126 {
3127 /* Narrow images may have no bits in a pass; the caller should handle
3128 * this, but this test is cheap:
3129 */
3130 if (row_width <= PNG_PASS_START_COL(pass))
3131 return;
3132
3133 if (pixel_depth < 8)
3134 {
3135 /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
3136 * into 32 bits, then a single loop over the bytes using the four byte
3137 * values in the 32-bit mask can be used. For the 'display' option the
3138 * expanded mask may also not require any masking within a byte. To
3139 * make this work the PACKSWAP option must be taken into account - it
3140 * simply requires the pixels to be reversed in each byte.
3141 *
3142 * The 'regular' case requires a mask for each of the first 6 passes,
3143 * the 'display' case does a copy for the even passes in the range
3144 * 0..6. This has already been handled in the test above.
3145 *
3146 * The masks are arranged as four bytes with the first byte to use in
3147 * the lowest bits (little-endian) regardless of the order (PACKSWAP or
3148 * not) of the pixels in each byte.
3149 *
3150 * NOTE: the whole of this logic depends on the caller of this function
3151 * only calling it on rows appropriate to the pass. This function only
3152 * understands the 'x' logic; the 'y' logic is handled by the caller.
3153 *
3154 * The following defines allow generation of compile time constant bit
3155 * masks for each pixel depth and each possibility of swapped or not
3156 * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index,
3157 * is in the range 0..7; and the result is 1 if the pixel is to be
3158 * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B'
3159 * for the block method.
3160 *
3161 * With some compilers a compile time expression of the general form:
3162 *
3163 * (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
3164 *
3165 * Produces warnings with values of 'shift' in the range 33 to 63
3166 * because the right hand side of the ?: expression is evaluated by
3167 * the compiler even though it isn't used. Microsoft Visual C (various
3168 * versions) and the Intel C compiler are known to do this. To avoid
3169 * this the following macros are used in 1.5.6. This is a temporary
3170 * solution to avoid destabilizing the code during the release process.
3171 */
3172 # if PNG_USE_COMPILE_TIME_MASKS
3173 # define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
3174 # define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
3175 # else
3176 # define PNG_LSR(x,s) ((x)>>(s))
3177 # define PNG_LSL(x,s) ((x)<<(s))
3178 # endif
3179 # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
3180 PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
3181 # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
3182 PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
3183
3184 /* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is
3185 * little endian - the first pixel is at bit 0 - however the extra
3186 * parameter 's' can be set to cause the mask position to be swapped
3187 * within each byte, to match the PNG format. This is done by XOR of
3188 * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
3189 */
3190 # define PIXEL_MASK(p,x,d,s) \
3191 (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
3192
3193 /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
3194 */
3195 # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3196 # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3197
3198 /* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp
3199 * cases the result needs replicating, for the 4-bpp case the above
3200 * generates a full 32 bits.
3201 */
3202 # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
3203
3204 # define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
3205 S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
3206 S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
3207
3208 # define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
3209 B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
3210 B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
3211
3212 #if PNG_USE_COMPILE_TIME_MASKS
3213 /* Utility macros to construct all the masks for a depth/swap
3214 * combination. The 's' parameter says whether the format is PNG
3215 * (big endian bytes) or not. Only the three odd-numbered passes are
3216 * required for the display/block algorithm.
3217 */
3218 # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
3219 S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
3220
3221 # define B_MASKS(d,s) { B_MASK(1,d,s), B_MASK(3,d,s), B_MASK(5,d,s) }
3222
3223 # define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
3224
3225 /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
3226 * then pass:
3227 */
3228 static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
3229 {
3230 /* Little-endian byte masks for PACKSWAP */
3231 { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
3232 /* Normal (big-endian byte) masks - PNG format */
3233 { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
3234 };
3235
3236 /* display_mask has only three entries for the odd passes, so index by
3237 * pass>>1.
3238 */
3239 static PNG_CONST png_uint_32 display_mask[2][3][3] =
3240 {
3241 /* Little-endian byte masks for PACKSWAP */
3242 { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
3243 /* Normal (big-endian byte) masks - PNG format */
3244 { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
3245 };
3246
3247 # define MASK(pass,depth,display,png)\
3248 ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
3249 row_mask[png][DEPTH_INDEX(depth)][pass])
3250
3251 #else /* !PNG_USE_COMPILE_TIME_MASKS */
3252 /* This is the runtime alternative: it seems unlikely that this will
3253 * ever be either smaller or faster than the compile time approach.
3254 */
3255 # define MASK(pass,depth,display,png)\
3256 ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
3257 #endif /* !USE_COMPILE_TIME_MASKS */
3258
3259 /* Use the appropriate mask to copy the required bits. In some cases
3260 * the byte mask will be 0 or 0xff; optimize these cases. row_width is
3261 * the number of pixels, but the code copies bytes, so it is necessary
3262 * to special case the end.
3263 */
3264 png_uint_32 pixels_per_byte = 8 / pixel_depth;
3265 png_uint_32 mask;
3266
3267 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3268 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
3269 mask = MASK(pass, pixel_depth, display, 0);
3270
3271 else
3272 # endif
3273 mask = MASK(pass, pixel_depth, display, 1);
3274
3275 for (;;)
3276 {
3277 png_uint_32 m;
3278
3279 /* It doesn't matter in the following if png_uint_32 has more than
3280 * 32 bits because the high bits always match those in m<<24; it is,
3281 * however, essential to use OR here, not +, because of this.
3282 */
3283 m = mask;
3284 mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
3285 m &= 0xff;
3286
3287 if (m != 0) /* something to copy */
3288 {
3289 if (m != 0xff)
3290 *dp = (png_byte)((*dp & ~m) | (*sp & m));
3291 else
3292 *dp = *sp;
3293 }
3294
3295 /* NOTE: this may overwrite the last byte with garbage if the image
3296 * is not an exact number of bytes wide; libpng has always done
3297 * this.
3298 */
3299 if (row_width <= pixels_per_byte)
3300 break; /* May need to restore part of the last byte */
3301
3302 row_width -= pixels_per_byte;
3303 ++dp;
3304 ++sp;
3305 }
3306 }
3307
3308 else /* pixel_depth >= 8 */
3309 {
3310 unsigned int bytes_to_copy, bytes_to_jump;
3311
3312 /* Validate the depth - it must be a multiple of 8 */
3313 if (pixel_depth & 7)
3314 png_error(png_ptr, "invalid user transform pixel depth");
3315
3316 pixel_depth >>= 3; /* now in bytes */
3317 row_width *= pixel_depth;
3318
3319 /* Regardless of pass number the Adam 7 interlace always results in a
3320 * fixed number of pixels to copy then to skip. There may be a
3321 * different number of pixels to skip at the start though.
3322 */
3323 {
3324 unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
3325
3326 row_width -= offset;
3327 dp += offset;
3328 sp += offset;
3329 }
3330
3331 /* Work out the bytes to copy. */
3332 if (display != 0)
3333 {
3334 /* When doing the 'block' algorithm the pixel in the pass gets
3335 * replicated to adjacent pixels. This is why the even (0,2,4,6)
3336 * passes are skipped above - the entire expanded row is copied.
3337 */
3338 bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
3339
3340 /* But don't allow this number to exceed the actual row width. */
3341 if (bytes_to_copy > row_width)
3342 bytes_to_copy = (unsigned int)/*SAFE*/row_width;
3343 }
3344
3345 else /* normal row; Adam7 only ever gives us one pixel to copy. */
3346 bytes_to_copy = pixel_depth;
3347
3348 /* In Adam7 there is a constant offset between where the pixels go. */
3349 bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
3350
3351 /* And simply copy these bytes. Some optimization is possible here,
3352 * depending on the value of 'bytes_to_copy'. Special case the low
3353 * byte counts, which we know to be frequent.
3354 *
3355 * Notice that these cases all 'return' rather than 'break' - this
3356 * avoids an unnecessary test on whether to restore the last byte
3357 * below.
3358 */
3359 switch (bytes_to_copy)
3360 {
3361 case 1:
3362 for (;;)
3363 {
3364 *dp = *sp;
3365
3366 if (row_width <= bytes_to_jump)
3367 return;
3368
3369 dp += bytes_to_jump;
3370 sp += bytes_to_jump;
3371 row_width -= bytes_to_jump;
3372 }
3373
3374 case 2:
3375 /* There is a possibility of a partial copy at the end here; this
3376 * slows the code down somewhat.
3377 */
3378 do
3379 {
3380 dp[0] = sp[0], dp[1] = sp[1];
3381
3382 if (row_width <= bytes_to_jump)
3383 return;
3384
3385 sp += bytes_to_jump;
3386 dp += bytes_to_jump;
3387 row_width -= bytes_to_jump;
3388 }
3389 while (row_width > 1);
3390
3391 /* And there can only be one byte left at this point: */
3392 *dp = *sp;
3393 return;
3394
3395 case 3:
3396 /* This can only be the RGB case, so each copy is exactly one
3397 * pixel and it is not necessary to check for a partial copy.
3398 */
3399 for (;;)
3400 {
3401 dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
3402
3403 if (row_width <= bytes_to_jump)
3404 return;
3405
3406 sp += bytes_to_jump;
3407 dp += bytes_to_jump;
3408 row_width -= bytes_to_jump;
3409 }
3410
3411 default:
3412 #if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
3413 /* Check for double byte alignment and, if possible, use a
3414 * 16-bit copy. Don't attempt this for narrow images - ones that
3415 * are less than an interlace panel wide. Don't attempt it for
3416 * wide bytes_to_copy either - use the memcpy there.
3417 */
3418 if (bytes_to_copy < 16 /*else use memcpy*/ &&
3419 png_isaligned(dp, png_uint_16) &&
3420 png_isaligned(sp, png_uint_16) &&
3421 bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
3422 bytes_to_jump % (sizeof (png_uint_16)) == 0)
3423 {
3424 /* Everything is aligned for png_uint_16 copies, but try for
3425 * png_uint_32 first.
3426 */
3427 if (png_isaligned(dp, png_uint_32) &&
3428 png_isaligned(sp, png_uint_32) &&
3429 bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
3430 bytes_to_jump % (sizeof (png_uint_32)) == 0)
3431 {
3432 png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
3433 png_const_uint_32p sp32 = png_aligncastconst(
3434 png_const_uint_32p, sp);
3435 size_t skip = (bytes_to_jump-bytes_to_copy) /
3436 (sizeof (png_uint_32));
3437
3438 do
3439 {
3440 size_t c = bytes_to_copy;
3441 do
3442 {
3443 *dp32++ = *sp32++;
3444 c -= (sizeof (png_uint_32));
3445 }
3446 while (c > 0);
3447
3448 if (row_width <= bytes_to_jump)
3449 return;
3450
3451 dp32 += skip;
3452 sp32 += skip;
3453 row_width -= bytes_to_jump;
3454 }
3455 while (bytes_to_copy <= row_width);
3456
3457 /* Get to here when the row_width truncates the final copy.
3458 * There will be 1-3 bytes left to copy, so don't try the
3459 * 16-bit loop below.
3460 */
3461 dp = (png_bytep)dp32;
3462 sp = (png_const_bytep)sp32;
3463 do
3464 *dp++ = *sp++;
3465 while (--row_width > 0);
3466 return;
3467 }
3468
3469 /* Else do it in 16-bit quantities, but only if the size is
3470 * not too large.
3471 */
3472 else
3473 {
3474 png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
3475 png_const_uint_16p sp16 = png_aligncastconst(
3476 png_const_uint_16p, sp);
3477 size_t skip = (bytes_to_jump-bytes_to_copy) /
3478 (sizeof (png_uint_16));
3479
3480 do
3481 {
3482 size_t c = bytes_to_copy;
3483 do
3484 {
3485 *dp16++ = *sp16++;
3486 c -= (sizeof (png_uint_16));
3487 }
3488 while (c > 0);
3489
3490 if (row_width <= bytes_to_jump)
3491 return;
3492
3493 dp16 += skip;
3494 sp16 += skip;
3495 row_width -= bytes_to_jump;
3496 }
3497 while (bytes_to_copy <= row_width);
3498
3499 /* End of row - 1 byte left, bytes_to_copy > row_width: */
3500 dp = (png_bytep)dp16;
3501 sp = (png_const_bytep)sp16;
3502 do
3503 *dp++ = *sp++;
3504 while (--row_width > 0);
3505 return;
3506 }
3507 }
3508 #endif /* ALIGN_TYPE code */
3509
3510 /* The true default - use a memcpy: */
3511 for (;;)
3512 {
3513 memcpy(dp, sp, bytes_to_copy);
3514
3515 if (row_width <= bytes_to_jump)
3516 return;
3517
3518 sp += bytes_to_jump;
3519 dp += bytes_to_jump;
3520 row_width -= bytes_to_jump;
3521 if (bytes_to_copy > row_width)
3522 bytes_to_copy = (unsigned int)/*SAFE*/row_width;
3523 }
3524 }
3525
3526 /* NOT REACHED*/
3527 } /* pixel_depth >= 8 */
3528
3529 /* Here if pixel_depth < 8 to check 'end_ptr' below. */
3530 }
3531 else
3532 #endif /* READ_INTERLACING */
3533
3534 /* If here then the switch above wasn't used so just memcpy the whole row
3535 * from the temporary row buffer (notice that this overwrites the end of the
3536 * destination row if it is a partial byte.)
3537 */
3538 memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
3539
3540 /* Restore the overwritten bits from the last byte if necessary. */
3541 if (end_ptr != NULL)
3542 *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
3543 }
3544
3545 #ifdef PNG_READ_INTERLACING_SUPPORTED
3546 void /* PRIVATE */
png_do_read_interlace(png_row_infop row_info,png_bytep row,int pass,png_uint_32 transformations)3547 png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
3548 png_uint_32 transformations /* Because these may affect the byte layout */)
3549 {
3550 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
3551 /* Offset to next interlace block */
3552 static PNG_CONST unsigned int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
3553
3554 png_debug(1, "in png_do_read_interlace");
3555 if (row != NULL && row_info != NULL)
3556 {
3557 png_uint_32 final_width;
3558
3559 final_width = row_info->width * png_pass_inc[pass];
3560
3561 switch (row_info->pixel_depth)
3562 {
3563 case 1:
3564 {
3565 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
3566 png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
3567 unsigned int sshift, dshift;
3568 unsigned int s_start, s_end;
3569 int s_inc;
3570 int jstop = (int)png_pass_inc[pass];
3571 png_byte v;
3572 png_uint_32 i;
3573 int j;
3574
3575 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3576 if ((transformations & PNG_PACKSWAP) != 0)
3577 {
3578 sshift = ((row_info->width + 7) & 0x07);
3579 dshift = ((final_width + 7) & 0x07);
3580 s_start = 7;
3581 s_end = 0;
3582 s_inc = -1;
3583 }
3584
3585 else
3586 #endif
3587 {
3588 sshift = 7 - ((row_info->width + 7) & 0x07);
3589 dshift = 7 - ((final_width + 7) & 0x07);
3590 s_start = 0;
3591 s_end = 7;
3592 s_inc = 1;
3593 }
3594
3595 for (i = 0; i < row_info->width; i++)
3596 {
3597 v = (png_byte)((*sp >> sshift) & 0x01);
3598 for (j = 0; j < jstop; j++)
3599 {
3600 unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
3601 tmp |= (unsigned int)(v << dshift);
3602 *dp = (png_byte)(tmp & 0xff);
3603
3604 if (dshift == s_end)
3605 {
3606 dshift = s_start;
3607 dp--;
3608 }
3609
3610 else
3611 dshift = (unsigned int)((int)dshift + s_inc);
3612 }
3613
3614 if (sshift == s_end)
3615 {
3616 sshift = s_start;
3617 sp--;
3618 }
3619
3620 else
3621 sshift = (unsigned int)((int)sshift + s_inc);
3622 }
3623 break;
3624 }
3625
3626 case 2:
3627 {
3628 png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
3629 png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
3630 unsigned int sshift, dshift;
3631 unsigned int s_start, s_end;
3632 int s_inc;
3633 int jstop = (int)png_pass_inc[pass];
3634 png_uint_32 i;
3635
3636 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3637 if ((transformations & PNG_PACKSWAP) != 0)
3638 {
3639 sshift = (((row_info->width + 3) & 0x03) << 1);
3640 dshift = (((final_width + 3) & 0x03) << 1);
3641 s_start = 6;
3642 s_end = 0;
3643 s_inc = -2;
3644 }
3645
3646 else
3647 #endif
3648 {
3649 sshift = ((3 - ((row_info->width + 3) & 0x03)) << 1);
3650 dshift = ((3 - ((final_width + 3) & 0x03)) << 1);
3651 s_start = 0;
3652 s_end = 6;
3653 s_inc = 2;
3654 }
3655
3656 for (i = 0; i < row_info->width; i++)
3657 {
3658 png_byte v;
3659 int j;
3660
3661 v = (png_byte)((*sp >> sshift) & 0x03);
3662 for (j = 0; j < jstop; j++)
3663 {
3664 unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
3665 tmp |= (unsigned int)(v << dshift);
3666 *dp = (png_byte)(tmp & 0xff);
3667
3668 if (dshift == s_end)
3669 {
3670 dshift = s_start;
3671 dp--;
3672 }
3673
3674 else
3675 dshift = (unsigned int)((int)dshift + s_inc);
3676 }
3677
3678 if (sshift == s_end)
3679 {
3680 sshift = s_start;
3681 sp--;
3682 }
3683
3684 else
3685 sshift = (unsigned int)((int)sshift + s_inc);
3686 }
3687 break;
3688 }
3689
3690 case 4:
3691 {
3692 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
3693 png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
3694 unsigned int sshift, dshift;
3695 unsigned int s_start, s_end;
3696 int s_inc;
3697 png_uint_32 i;
3698 int jstop = (int)png_pass_inc[pass];
3699
3700 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3701 if ((transformations & PNG_PACKSWAP) != 0)
3702 {
3703 sshift = (((row_info->width + 1) & 0x01) << 2);
3704 dshift = (((final_width + 1) & 0x01) << 2);
3705 s_start = 4;
3706 s_end = 0;
3707 s_inc = -4;
3708 }
3709
3710 else
3711 #endif
3712 {
3713 sshift = ((1 - ((row_info->width + 1) & 0x01)) << 2);
3714 dshift = ((1 - ((final_width + 1) & 0x01)) << 2);
3715 s_start = 0;
3716 s_end = 4;
3717 s_inc = 4;
3718 }
3719
3720 for (i = 0; i < row_info->width; i++)
3721 {
3722 png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
3723 int j;
3724
3725 for (j = 0; j < jstop; j++)
3726 {
3727 unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
3728 tmp |= (unsigned int)(v << dshift);
3729 *dp = (png_byte)(tmp & 0xff);
3730
3731 if (dshift == s_end)
3732 {
3733 dshift = s_start;
3734 dp--;
3735 }
3736
3737 else
3738 dshift = (unsigned int)((int)dshift + s_inc);
3739 }
3740
3741 if (sshift == s_end)
3742 {
3743 sshift = s_start;
3744 sp--;
3745 }
3746
3747 else
3748 sshift = (unsigned int)((int)sshift + s_inc);
3749 }
3750 break;
3751 }
3752
3753 default:
3754 {
3755 png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
3756
3757 png_bytep sp = row + (png_size_t)(row_info->width - 1)
3758 * pixel_bytes;
3759
3760 png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
3761
3762 int jstop = (int)png_pass_inc[pass];
3763 png_uint_32 i;
3764
3765 for (i = 0; i < row_info->width; i++)
3766 {
3767 png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
3768 int j;
3769
3770 memcpy(v, sp, pixel_bytes);
3771
3772 for (j = 0; j < jstop; j++)
3773 {
3774 memcpy(dp, v, pixel_bytes);
3775 dp -= pixel_bytes;
3776 }
3777
3778 sp -= pixel_bytes;
3779 }
3780 break;
3781 }
3782 }
3783
3784 row_info->width = final_width;
3785 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
3786 }
3787 #ifndef PNG_READ_PACKSWAP_SUPPORTED
3788 PNG_UNUSED(transformations) /* Silence compiler warning */
3789 #endif
3790 }
3791 #endif /* READ_INTERLACING */
3792
3793 static void
png_read_filter_row_sub(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3794 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
3795 png_const_bytep prev_row)
3796 {
3797 png_size_t i;
3798 png_size_t istop = row_info->rowbytes;
3799 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3800 png_bytep rp = row + bpp;
3801
3802 PNG_UNUSED(prev_row)
3803
3804 for (i = bpp; i < istop; i++)
3805 {
3806 *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
3807 rp++;
3808 }
3809 }
3810
3811 static void
png_read_filter_row_up(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3812 png_read_filter_row_up(png_row_infop row_info, png_bytep row,
3813 png_const_bytep prev_row)
3814 {
3815 png_size_t i;
3816 png_size_t istop = row_info->rowbytes;
3817 png_bytep rp = row;
3818 png_const_bytep pp = prev_row;
3819
3820 for (i = 0; i < istop; i++)
3821 {
3822 *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
3823 rp++;
3824 }
3825 }
3826
3827 static void
png_read_filter_row_avg(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3828 png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
3829 png_const_bytep prev_row)
3830 {
3831 png_size_t i;
3832 png_bytep rp = row;
3833 png_const_bytep pp = prev_row;
3834 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3835 png_size_t istop = row_info->rowbytes - bpp;
3836
3837 for (i = 0; i < bpp; i++)
3838 {
3839 *rp = (png_byte)(((int)(*rp) +
3840 ((int)(*pp++) / 2 )) & 0xff);
3841
3842 rp++;
3843 }
3844
3845 for (i = 0; i < istop; i++)
3846 {
3847 *rp = (png_byte)(((int)(*rp) +
3848 (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
3849
3850 rp++;
3851 }
3852 }
3853
3854 static void
png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3855 png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
3856 png_const_bytep prev_row)
3857 {
3858 png_bytep rp_end = row + row_info->rowbytes;
3859 int a, c;
3860
3861 /* First pixel/byte */
3862 c = *prev_row++;
3863 a = *row + c;
3864 *row++ = (png_byte)a;
3865
3866 /* Remainder */
3867 while (row < rp_end)
3868 {
3869 int b, pa, pb, pc, p;
3870
3871 a &= 0xff; /* From previous iteration or start */
3872 b = *prev_row++;
3873
3874 p = b - c;
3875 pc = a - c;
3876
3877 #ifdef PNG_USE_ABS
3878 pa = abs(p);
3879 pb = abs(pc);
3880 pc = abs(p + pc);
3881 #else
3882 pa = p < 0 ? -p : p;
3883 pb = pc < 0 ? -pc : pc;
3884 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3885 #endif
3886
3887 /* Find the best predictor, the least of pa, pb, pc favoring the earlier
3888 * ones in the case of a tie.
3889 */
3890 if (pb < pa) pa = pb, a = b;
3891 if (pc < pa) a = c;
3892
3893 /* Calculate the current pixel in a, and move the previous row pixel to c
3894 * for the next time round the loop
3895 */
3896 c = b;
3897 a += *row;
3898 *row++ = (png_byte)a;
3899 }
3900 }
3901
3902 static void
png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info,png_bytep row,png_const_bytep prev_row)3903 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
3904 png_const_bytep prev_row)
3905 {
3906 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3907 png_bytep rp_end = row + bpp;
3908
3909 /* Process the first pixel in the row completely (this is the same as 'up'
3910 * because there is only one candidate predictor for the first row).
3911 */
3912 while (row < rp_end)
3913 {
3914 int a = *row + *prev_row++;
3915 *row++ = (png_byte)a;
3916 }
3917
3918 /* Remainder */
3919 rp_end = rp_end + (row_info->rowbytes - bpp);
3920
3921 while (row < rp_end)
3922 {
3923 int a, b, c, pa, pb, pc, p;
3924
3925 c = *(prev_row - bpp);
3926 a = *(row - bpp);
3927 b = *prev_row++;
3928
3929 p = b - c;
3930 pc = a - c;
3931
3932 #ifdef PNG_USE_ABS
3933 pa = abs(p);
3934 pb = abs(pc);
3935 pc = abs(p + pc);
3936 #else
3937 pa = p < 0 ? -p : p;
3938 pb = pc < 0 ? -pc : pc;
3939 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3940 #endif
3941
3942 if (pb < pa) pa = pb, a = b;
3943 if (pc < pa) a = c;
3944
3945 a += *row;
3946 *row++ = (png_byte)a;
3947 }
3948 }
3949
3950 static void
png_init_filter_functions(png_structrp pp)3951 png_init_filter_functions(png_structrp pp)
3952 /* This function is called once for every PNG image (except for PNG images
3953 * that only use PNG_FILTER_VALUE_NONE for all rows) to set the
3954 * implementations required to reverse the filtering of PNG rows. Reversing
3955 * the filter is the first transformation performed on the row data. It is
3956 * performed in place, therefore an implementation can be selected based on
3957 * the image pixel format. If the implementation depends on image width then
3958 * take care to ensure that it works correctly if the image is interlaced -
3959 * interlacing causes the actual row width to vary.
3960 */
3961 {
3962 unsigned int bpp = (pp->pixel_depth + 7) >> 3;
3963
3964 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
3965 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
3966 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
3967 if (bpp == 1)
3968 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
3969 png_read_filter_row_paeth_1byte_pixel;
3970 else
3971 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
3972 png_read_filter_row_paeth_multibyte_pixel;
3973
3974 #ifdef PNG_FILTER_OPTIMIZATIONS
3975 /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
3976 * call to install hardware optimizations for the above functions; simply
3977 * replace whatever elements of the pp->read_filter[] array with a hardware
3978 * specific (or, for that matter, generic) optimization.
3979 *
3980 * To see an example of this examine what configure.ac does when
3981 * --enable-arm-neon is specified on the command line.
3982 */
3983 PNG_FILTER_OPTIMIZATIONS(pp, bpp);
3984 #endif
3985 }
3986
3987 void /* PRIVATE */
png_read_filter_row(png_structrp pp,png_row_infop row_info,png_bytep row,png_const_bytep prev_row,int filter)3988 png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
3989 png_const_bytep prev_row, int filter)
3990 {
3991 /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
3992 * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
3993 * implementations. See png_init_filter_functions above.
3994 */
3995 if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
3996 {
3997 if (pp->read_filter[0] == NULL)
3998 png_init_filter_functions(pp);
3999
4000 pp->read_filter[filter-1](row_info, row, prev_row);
4001 }
4002 }
4003
4004 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
4005 void /* PRIVATE */
png_read_IDAT_data(png_structrp png_ptr,png_bytep output,png_alloc_size_t avail_out)4006 png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
4007 png_alloc_size_t avail_out)
4008 {
4009 /* Loop reading IDATs and decompressing the result into output[avail_out] */
4010 png_ptr->zstream.next_out = output;
4011 png_ptr->zstream.avail_out = 0; /* safety: set below */
4012
4013 if (output == NULL)
4014 avail_out = 0;
4015
4016 do
4017 {
4018 int ret;
4019 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
4020
4021 if (png_ptr->zstream.avail_in == 0)
4022 {
4023 uInt avail_in;
4024 png_bytep buffer;
4025
4026 while (png_ptr->idat_size == 0)
4027 {
4028 png_crc_finish(png_ptr, 0);
4029
4030 png_ptr->idat_size = png_read_chunk_header(png_ptr);
4031 /* This is an error even in the 'check' case because the code just
4032 * consumed a non-IDAT header.
4033 */
4034 if (png_ptr->chunk_name != png_IDAT)
4035 png_error(png_ptr, "Not enough image data");
4036 }
4037
4038 avail_in = png_ptr->IDAT_read_size;
4039
4040 if (avail_in > png_ptr->idat_size)
4041 avail_in = (uInt)png_ptr->idat_size;
4042
4043 /* A PNG with a gradually increasing IDAT size will defeat this attempt
4044 * to minimize memory usage by causing lots of re-allocs, but
4045 * realistically doing IDAT_read_size re-allocs is not likely to be a
4046 * big problem.
4047 */
4048 buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
4049
4050 png_crc_read(png_ptr, buffer, avail_in);
4051 png_ptr->idat_size -= avail_in;
4052
4053 png_ptr->zstream.next_in = buffer;
4054 png_ptr->zstream.avail_in = avail_in;
4055 }
4056
4057 /* And set up the output side. */
4058 if (output != NULL) /* standard read */
4059 {
4060 uInt out = ZLIB_IO_MAX;
4061
4062 if (out > avail_out)
4063 out = (uInt)avail_out;
4064
4065 avail_out -= out;
4066 png_ptr->zstream.avail_out = out;
4067 }
4068
4069 else /* after last row, checking for end */
4070 {
4071 png_ptr->zstream.next_out = tmpbuf;
4072 png_ptr->zstream.avail_out = (sizeof tmpbuf);
4073 }
4074
4075 /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
4076 * process. If the LZ stream is truncated the sequential reader will
4077 * terminally damage the stream, above, by reading the chunk header of the
4078 * following chunk (it then exits with png_error).
4079 *
4080 * TODO: deal more elegantly with truncated IDAT lists.
4081 */
4082 ret = PNG_INFLATE(png_ptr, Z_NO_FLUSH);
4083
4084 /* Take the unconsumed output back. */
4085 if (output != NULL)
4086 avail_out += png_ptr->zstream.avail_out;
4087
4088 else /* avail_out counts the extra bytes */
4089 avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
4090
4091 png_ptr->zstream.avail_out = 0;
4092
4093 if (ret == Z_STREAM_END)
4094 {
4095 /* Do this for safety; we won't read any more into this row. */
4096 png_ptr->zstream.next_out = NULL;
4097
4098 png_ptr->mode |= PNG_AFTER_IDAT;
4099 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4100
4101 if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
4102 png_chunk_benign_error(png_ptr, "Extra compressed data");
4103 break;
4104 }
4105
4106 if (ret != Z_OK)
4107 {
4108 png_zstream_error(png_ptr, ret);
4109
4110 if (output != NULL)
4111 png_chunk_error(png_ptr, png_ptr->zstream.msg);
4112
4113 else /* checking */
4114 {
4115 png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
4116 return;
4117 }
4118 }
4119 } while (avail_out > 0);
4120
4121 if (avail_out > 0)
4122 {
4123 /* The stream ended before the image; this is the same as too few IDATs so
4124 * should be handled the same way.
4125 */
4126 if (output != NULL)
4127 png_error(png_ptr, "Not enough image data");
4128
4129 else /* the deflate stream contained extra data */
4130 png_chunk_benign_error(png_ptr, "Too much image data");
4131 }
4132 }
4133
4134 void /* PRIVATE */
png_read_finish_IDAT(png_structrp png_ptr)4135 png_read_finish_IDAT(png_structrp png_ptr)
4136 {
4137 /* We don't need any more data and the stream should have ended, however the
4138 * LZ end code may actually not have been processed. In this case we must
4139 * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
4140 * may still remain to be consumed.
4141 */
4142 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
4143 {
4144 /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
4145 * the compressed stream, but the stream may be damaged too, so even after
4146 * this call we may need to terminate the zstream ownership.
4147 */
4148 png_read_IDAT_data(png_ptr, NULL, 0);
4149 png_ptr->zstream.next_out = NULL; /* safety */
4150
4151 /* Now clear everything out for safety; the following may not have been
4152 * done.
4153 */
4154 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
4155 {
4156 png_ptr->mode |= PNG_AFTER_IDAT;
4157 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4158 }
4159 }
4160
4161 /* If the zstream has not been released do it now *and* terminate the reading
4162 * of the final IDAT chunk.
4163 */
4164 if (png_ptr->zowner == png_IDAT)
4165 {
4166 /* Always do this; the pointers otherwise point into the read buffer. */
4167 png_ptr->zstream.next_in = NULL;
4168 png_ptr->zstream.avail_in = 0;
4169
4170 /* Now we no longer own the zstream. */
4171 png_ptr->zowner = 0;
4172
4173 /* The slightly weird semantics of the sequential IDAT reading is that we
4174 * are always in or at the end of an IDAT chunk, so we always need to do a
4175 * crc_finish here. If idat_size is non-zero we also need to read the
4176 * spurious bytes at the end of the chunk now.
4177 */
4178 (void)png_crc_finish(png_ptr, png_ptr->idat_size);
4179 }
4180 }
4181
4182 void /* PRIVATE */
png_read_finish_row(png_structrp png_ptr)4183 png_read_finish_row(png_structrp png_ptr)
4184 {
4185 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4186
4187 /* Start of interlace block */
4188 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4189
4190 /* Offset to next interlace block */
4191 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4192
4193 /* Start of interlace block in the y direction */
4194 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4195
4196 /* Offset to next interlace block in the y direction */
4197 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4198
4199 png_debug(1, "in png_read_finish_row");
4200 png_ptr->row_number++;
4201 if (png_ptr->row_number < png_ptr->num_rows)
4202 return;
4203
4204 if (png_ptr->interlaced != 0)
4205 {
4206 png_ptr->row_number = 0;
4207
4208 /* TO DO: don't do this if prev_row isn't needed (requires
4209 * read-ahead of the next row's filter byte.
4210 */
4211 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4212
4213 do
4214 {
4215 png_ptr->pass++;
4216
4217 if (png_ptr->pass >= 7)
4218 break;
4219
4220 png_ptr->iwidth = (png_ptr->width +
4221 png_pass_inc[png_ptr->pass] - 1 -
4222 png_pass_start[png_ptr->pass]) /
4223 png_pass_inc[png_ptr->pass];
4224
4225 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4226 {
4227 png_ptr->num_rows = (png_ptr->height +
4228 png_pass_yinc[png_ptr->pass] - 1 -
4229 png_pass_ystart[png_ptr->pass]) /
4230 png_pass_yinc[png_ptr->pass];
4231 }
4232
4233 else /* if (png_ptr->transformations & PNG_INTERLACE) */
4234 break; /* libpng deinterlacing sees every row */
4235
4236 } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
4237
4238 if (png_ptr->pass < 7)
4239 return;
4240 }
4241
4242 /* Here after at the end of the last row of the last pass. */
4243 png_read_finish_IDAT(png_ptr);
4244 }
4245 #endif /* SEQUENTIAL_READ */
4246
4247 void /* PRIVATE */
png_read_start_row(png_structrp png_ptr)4248 png_read_start_row(png_structrp png_ptr)
4249 {
4250 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4251
4252 /* Start of interlace block */
4253 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4254
4255 /* Offset to next interlace block */
4256 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4257
4258 /* Start of interlace block in the y direction */
4259 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4260
4261 /* Offset to next interlace block in the y direction */
4262 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4263
4264 unsigned int max_pixel_depth;
4265 png_size_t row_bytes;
4266
4267 png_debug(1, "in png_read_start_row");
4268
4269 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
4270 png_init_read_transformations(png_ptr);
4271 #endif
4272 if (png_ptr->interlaced != 0)
4273 {
4274 if ((png_ptr->transformations & PNG_INTERLACE) == 0)
4275 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
4276 png_pass_ystart[0]) / png_pass_yinc[0];
4277
4278 else
4279 png_ptr->num_rows = png_ptr->height;
4280
4281 png_ptr->iwidth = (png_ptr->width +
4282 png_pass_inc[png_ptr->pass] - 1 -
4283 png_pass_start[png_ptr->pass]) /
4284 png_pass_inc[png_ptr->pass];
4285 }
4286
4287 else
4288 {
4289 png_ptr->num_rows = png_ptr->height;
4290 png_ptr->iwidth = png_ptr->width;
4291 }
4292
4293 max_pixel_depth = (unsigned int)png_ptr->pixel_depth;
4294
4295 /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of
4296 * calculations to calculate the final pixel depth, then
4297 * png_do_read_transforms actually does the transforms. This means that the
4298 * code which effectively calculates this value is actually repeated in three
4299 * separate places. They must all match. Innocent changes to the order of
4300 * transformations can and will break libpng in a way that causes memory
4301 * overwrites.
4302 *
4303 * TODO: fix this.
4304 */
4305 #ifdef PNG_READ_PACK_SUPPORTED
4306 if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8)
4307 max_pixel_depth = 8;
4308 #endif
4309
4310 #ifdef PNG_READ_EXPAND_SUPPORTED
4311 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4312 {
4313 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4314 {
4315 if (png_ptr->num_trans != 0)
4316 max_pixel_depth = 32;
4317
4318 else
4319 max_pixel_depth = 24;
4320 }
4321
4322 else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4323 {
4324 if (max_pixel_depth < 8)
4325 max_pixel_depth = 8;
4326
4327 if (png_ptr->num_trans != 0)
4328 max_pixel_depth *= 2;
4329 }
4330
4331 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
4332 {
4333 if (png_ptr->num_trans != 0)
4334 {
4335 max_pixel_depth *= 4;
4336 max_pixel_depth /= 3;
4337 }
4338 }
4339 }
4340 #endif
4341
4342 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4343 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4344 {
4345 # ifdef PNG_READ_EXPAND_SUPPORTED
4346 /* In fact it is an error if it isn't supported, but checking is
4347 * the safe way.
4348 */
4349 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4350 {
4351 if (png_ptr->bit_depth < 16)
4352 max_pixel_depth *= 2;
4353 }
4354 else
4355 # endif
4356 png_ptr->transformations &= ~PNG_EXPAND_16;
4357 }
4358 #endif
4359
4360 #ifdef PNG_READ_FILLER_SUPPORTED
4361 if ((png_ptr->transformations & (PNG_FILLER)) != 0)
4362 {
4363 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4364 {
4365 if (max_pixel_depth <= 8)
4366 max_pixel_depth = 16;
4367
4368 else
4369 max_pixel_depth = 32;
4370 }
4371
4372 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
4373 png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4374 {
4375 if (max_pixel_depth <= 32)
4376 max_pixel_depth = 32;
4377
4378 else
4379 max_pixel_depth = 64;
4380 }
4381 }
4382 #endif
4383
4384 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4385 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
4386 {
4387 if (
4388 #ifdef PNG_READ_EXPAND_SUPPORTED
4389 (png_ptr->num_trans != 0 &&
4390 (png_ptr->transformations & PNG_EXPAND) != 0) ||
4391 #endif
4392 #ifdef PNG_READ_FILLER_SUPPORTED
4393 (png_ptr->transformations & (PNG_FILLER)) != 0 ||
4394 #endif
4395 png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4396 {
4397 if (max_pixel_depth <= 16)
4398 max_pixel_depth = 32;
4399
4400 else
4401 max_pixel_depth = 64;
4402 }
4403
4404 else
4405 {
4406 if (max_pixel_depth <= 8)
4407 {
4408 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4409 max_pixel_depth = 32;
4410
4411 else
4412 max_pixel_depth = 24;
4413 }
4414
4415 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4416 max_pixel_depth = 64;
4417
4418 else
4419 max_pixel_depth = 48;
4420 }
4421 }
4422 #endif
4423
4424 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
4425 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
4426 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
4427 {
4428 unsigned int user_pixel_depth = png_ptr->user_transform_depth *
4429 png_ptr->user_transform_channels;
4430
4431 if (user_pixel_depth > max_pixel_depth)
4432 max_pixel_depth = user_pixel_depth;
4433 }
4434 #endif
4435
4436 /* This value is stored in png_struct and double checked in the row read
4437 * code.
4438 */
4439 png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
4440 png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
4441
4442 /* Align the width on the next larger 8 pixels. Mainly used
4443 * for interlacing
4444 */
4445 row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
4446 /* Calculate the maximum bytes needed, adding a byte and a pixel
4447 * for safety's sake
4448 */
4449 row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
4450 1 + ((max_pixel_depth + 7) >> 3U);
4451
4452 #ifdef PNG_MAX_MALLOC_64K
4453 if (row_bytes > (png_uint_32)65536L)
4454 png_error(png_ptr, "This image requires a row greater than 64KB");
4455 #endif
4456
4457 if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
4458 {
4459 png_free(png_ptr, png_ptr->big_row_buf);
4460 png_free(png_ptr, png_ptr->big_prev_row);
4461
4462 if (png_ptr->interlaced != 0)
4463 png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
4464 row_bytes + 48);
4465
4466 else
4467 png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4468
4469 png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4470
4471 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
4472 /* Use 16-byte aligned memory for row_buf with at least 16 bytes
4473 * of padding before and after row_buf; treat prev_row similarly.
4474 * NOTE: the alignment is to the start of the pixels, one beyond the start
4475 * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this
4476 * was incorrect; the filter byte was aligned, which had the exact
4477 * opposite effect of that intended.
4478 */
4479 {
4480 png_bytep temp = png_ptr->big_row_buf + 32;
4481 int extra = (int)((temp - (png_bytep)0) & 0x0f);
4482 png_ptr->row_buf = temp - extra - 1/*filter byte*/;
4483
4484 temp = png_ptr->big_prev_row + 32;
4485 extra = (int)((temp - (png_bytep)0) & 0x0f);
4486 png_ptr->prev_row = temp - extra - 1/*filter byte*/;
4487 }
4488
4489 #else
4490 /* Use 31 bytes of padding before and 17 bytes after row_buf. */
4491 png_ptr->row_buf = png_ptr->big_row_buf + 31;
4492 png_ptr->prev_row = png_ptr->big_prev_row + 31;
4493 #endif
4494 png_ptr->old_big_row_buf_size = row_bytes + 48;
4495 }
4496
4497 #ifdef PNG_MAX_MALLOC_64K
4498 if (png_ptr->rowbytes > 65535)
4499 png_error(png_ptr, "This image requires a row greater than 64KB");
4500
4501 #endif
4502 if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
4503 png_error(png_ptr, "Row has too many bytes to allocate in memory");
4504
4505 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4506
4507 png_debug1(3, "width = %u,", png_ptr->width);
4508 png_debug1(3, "height = %u,", png_ptr->height);
4509 png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
4510 png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
4511 png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
4512 png_debug1(3, "irowbytes = %lu",
4513 (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
4514
4515 /* The sequential reader needs a buffer for IDAT, but the progressive reader
4516 * does not, so free the read buffer now regardless; the sequential reader
4517 * reallocates it on demand.
4518 */
4519 if (png_ptr->read_buffer != NULL)
4520 {
4521 png_bytep buffer = png_ptr->read_buffer;
4522
4523 png_ptr->read_buffer_size = 0;
4524 png_ptr->read_buffer = NULL;
4525 png_free(png_ptr, buffer);
4526 }
4527
4528 /* Finally claim the zstream for the inflate of the IDAT data, use the bits
4529 * value from the stream (note that this will result in a fatal error if the
4530 * IDAT stream has a bogus deflate header window_bits value, but this should
4531 * not be happening any longer!)
4532 */
4533 if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
4534 png_error(png_ptr, png_ptr->zstream.msg);
4535
4536 png_ptr->flags |= PNG_FLAG_ROW_INIT;
4537 }
4538 #endif /* READ */
4539