Check for SYS/GL during library init. Reason is that
[AROS.git] / workbench / libs / png / pngrutil.c
blob0a75cd81ce39889fb7c4a20390732e26b186d5ec
2 /* pngrutil.c - utilities to read a PNG file
4 * Last changed in libpng 1.6.3 [July 18, 2013]
5 * Copyright (c) 1998-2013 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.)
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
13 * This file contains routines that are only called from within
14 * libpng itself during the course of reading an image.
17 #include "pngpriv.h"
19 #ifdef PNG_READ_SUPPORTED
21 png_uint_32 PNGAPI
22 png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
24 png_uint_32 uval = png_get_uint_32(buf);
26 if (uval > PNG_UINT_31_MAX)
27 png_error(png_ptr, "PNG unsigned integer out of range");
29 return (uval);
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.
38 #define PNG_FIXED_ERROR (-1)
40 static png_fixed_point /* PRIVATE */
41 png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
43 png_uint_32 uval = png_get_uint_32(buf);
45 if (uval <= PNG_UINT_31_MAX)
46 return (png_fixed_point)uval; /* known to be in range */
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");
52 return PNG_FIXED_ERROR;
54 #endif
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.
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.
66 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
67 png_uint_32 (PNGAPI
68 png_get_uint_32)(png_const_bytep buf)
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)) ) ;
76 return uval;
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.
84 png_int_32 (PNGAPI
85 png_get_int_32)(png_const_bytep buf)
87 png_uint_32 uval = png_get_uint_32(buf);
88 if ((uval & 0x80000000) == 0) /* non-negative */
89 return uval;
91 uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */
92 return -(png_int_32)uval;
95 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
96 png_uint_16 (PNGAPI
97 png_get_uint_16)(png_const_bytep buf)
99 /* ANSI-C requires an int value to accomodate at least 16 bits so this
100 * works and allows the compiler not to worry about possible narrowing
101 * on 32 bit systems. (Pre-ANSI systems did not make integers smaller
102 * than 16 bits either.)
104 unsigned int val =
105 ((unsigned int)(*buf) << 8) +
106 ((unsigned int)(*(buf + 1)));
108 return (png_uint_16)val;
111 #endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
113 /* Read and check the PNG file signature */
114 void /* PRIVATE */
115 png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
117 png_size_t num_checked, num_to_check;
119 /* Exit if the user application does not expect a signature. */
120 if (png_ptr->sig_bytes >= 8)
121 return;
123 num_checked = png_ptr->sig_bytes;
124 num_to_check = 8 - num_checked;
126 #ifdef PNG_IO_STATE_SUPPORTED
127 png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
128 #endif
130 /* The signature must be serialized in a single I/O call. */
131 png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
132 png_ptr->sig_bytes = 8;
134 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
136 if (num_checked < 4 &&
137 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
138 png_error(png_ptr, "Not a PNG file");
139 else
140 png_error(png_ptr, "PNG file corrupted by ASCII conversion");
142 if (num_checked < 3)
143 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
146 /* Read the chunk header (length + type name).
147 * Put the type name into png_ptr->chunk_name, and return the length.
149 png_uint_32 /* PRIVATE */
150 png_read_chunk_header(png_structrp png_ptr)
152 png_byte buf[8];
153 png_uint_32 length;
155 #ifdef PNG_IO_STATE_SUPPORTED
156 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
157 #endif
159 /* Read the length and the chunk name.
160 * This must be performed in a single I/O call.
162 png_read_data(png_ptr, buf, 8);
163 length = png_get_uint_31(png_ptr, buf);
165 /* Put the chunk name into png_ptr->chunk_name. */
166 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
168 png_debug2(0, "Reading %lx chunk, length = %lu",
169 (unsigned long)png_ptr->chunk_name, (unsigned long)length);
171 /* Reset the crc and run it over the chunk name. */
172 png_reset_crc(png_ptr);
173 png_calculate_crc(png_ptr, buf + 4, 4);
175 /* Check to see if chunk name is valid. */
176 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
178 #ifdef PNG_IO_STATE_SUPPORTED
179 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
180 #endif
182 return length;
185 /* Read data, and (optionally) run it through the CRC. */
186 void /* PRIVATE */
187 png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
189 if (png_ptr == NULL)
190 return;
192 png_read_data(png_ptr, buf, length);
193 png_calculate_crc(png_ptr, buf, length);
196 /* Optionally skip data and then check the CRC. Depending on whether we
197 * are reading an ancillary or critical chunk, and how the program has set
198 * things up, we may calculate the CRC on the data and print a message.
199 * Returns '1' if there was a CRC error, '0' otherwise.
201 int /* PRIVATE */
202 png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
204 /* The size of the local buffer for inflate is a good guess as to a
205 * reasonable size to use for buffering reads from the application.
207 while (skip > 0)
209 png_uint_32 len;
210 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
212 len = (sizeof tmpbuf);
213 if (len > skip)
214 len = skip;
215 skip -= len;
217 png_crc_read(png_ptr, tmpbuf, len);
220 if (png_crc_error(png_ptr))
222 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) ?
223 !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
224 (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
226 png_chunk_warning(png_ptr, "CRC error");
229 else
231 png_chunk_benign_error(png_ptr, "CRC error");
232 return (0);
235 return (1);
238 return (0);
241 /* Compare the CRC stored in the PNG file with that calculated by libpng from
242 * the data it has read thus far.
244 int /* PRIVATE */
245 png_crc_error(png_structrp png_ptr)
247 png_byte crc_bytes[4];
248 png_uint_32 crc;
249 int need_crc = 1;
251 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
253 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
254 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
255 need_crc = 0;
258 else /* critical */
260 if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
261 need_crc = 0;
264 #ifdef PNG_IO_STATE_SUPPORTED
265 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
266 #endif
268 /* The chunk CRC must be serialized in a single I/O call. */
269 png_read_data(png_ptr, crc_bytes, 4);
271 if (need_crc)
273 crc = png_get_uint_32(crc_bytes);
274 return ((int)(crc != png_ptr->crc));
277 else
278 return (0);
281 /* Manage the read buffer; this simply reallocates the buffer if it is not small
282 * enough (or if it is not allocated). The routine returns a pointer to the
283 * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
284 * it will call png_error (via png_malloc) on failure. (warn == 2 means
285 * 'silent').
287 static png_bytep
288 png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
290 png_bytep buffer = png_ptr->read_buffer;
292 if (buffer != NULL && new_size > png_ptr->read_buffer_size)
294 png_ptr->read_buffer = NULL;
295 png_ptr->read_buffer = NULL;
296 png_ptr->read_buffer_size = 0;
297 png_free(png_ptr, buffer);
298 buffer = NULL;
301 if (buffer == NULL)
303 buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
305 if (buffer != NULL)
307 png_ptr->read_buffer = buffer;
308 png_ptr->read_buffer_size = new_size;
311 else if (warn < 2) /* else silent */
313 #ifdef PNG_WARNINGS_SUPPORTED
314 if (warn)
315 png_chunk_warning(png_ptr, "insufficient memory to read chunk");
316 else
317 #endif
319 #ifdef PNG_ERROR_TEXT_SUPPORTED
320 png_chunk_error(png_ptr, "insufficient memory to read chunk");
321 #endif
326 return buffer;
329 /* png_inflate_claim: claim the zstream for some nefarious purpose that involves
330 * decompression. Returns Z_OK on success, else a zlib error code. It checks
331 * the owner but, in final release builds, just issues a warning if some other
332 * chunk apparently owns the stream. Prior to release it does a png_error.
334 static int
335 png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
337 if (png_ptr->zowner != 0)
339 char msg[64];
341 PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
342 /* So the message that results is "<chunk> using zstream"; this is an
343 * internal error, but is very useful for debugging. i18n requirements
344 * are minimal.
346 (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
347 # if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
348 png_chunk_warning(png_ptr, msg);
349 png_ptr->zowner = 0;
350 # else
351 png_chunk_error(png_ptr, msg);
352 # endif
355 /* Implementation note: unlike 'png_deflate_claim' this internal function
356 * does not take the size of the data as an argument. Some efficiency could
357 * be gained by using this when it is known *if* the zlib stream itself does
358 * not record the number; however, this is an illusion: the original writer
359 * of the PNG may have selected a lower window size, and we really must
360 * follow that because, for systems with with limited capabilities, we
361 * would otherwise reject the application's attempts to use a smaller window
362 * size (zlib doesn't have an interface to say "this or lower"!).
364 * inflateReset2 was added to zlib 1.2.4; before this the window could not be
365 * reset, therefore it is necessary to always allocate the maximum window
366 * size with earlier zlibs just in case later compressed chunks need it.
369 int ret; /* zlib return code */
370 # if PNG_ZLIB_VERNUM >= 0x1240
372 # if defined(PNG_SET_OPTION_SUPPORTED) && \
373 defined(PNG_MAXIMUM_INFLATE_WINDOW)
374 int window_bits;
376 if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
377 PNG_OPTION_ON)
378 window_bits = 15;
380 else
381 window_bits = 0;
382 # else
383 # define window_bits 0
384 # endif
385 # endif
387 /* Set this for safety, just in case the previous owner left pointers to
388 * memory allocations.
390 png_ptr->zstream.next_in = NULL;
391 png_ptr->zstream.avail_in = 0;
392 png_ptr->zstream.next_out = NULL;
393 png_ptr->zstream.avail_out = 0;
395 if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
397 # if PNG_ZLIB_VERNUM < 0x1240
398 ret = inflateReset(&png_ptr->zstream);
399 # else
400 ret = inflateReset2(&png_ptr->zstream, window_bits);
401 # endif
404 else
406 # if PNG_ZLIB_VERNUM < 0x1240
407 ret = inflateInit(&png_ptr->zstream);
408 # else
409 ret = inflateInit2(&png_ptr->zstream, window_bits);
410 # endif
412 if (ret == Z_OK)
413 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
416 if (ret == Z_OK)
417 png_ptr->zowner = owner;
419 else
420 png_zstream_error(png_ptr, ret);
422 return ret;
425 # ifdef window_bits
426 # undef window_bits
427 # endif
430 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
431 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
432 * allow the caller to do multiple calls if required. If the 'finish' flag is
433 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
434 * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
435 * Z_OK or Z_STREAM_END will be returned on success.
437 * The input and output sizes are updated to the actual amounts of data consumed
438 * or written, not the amount available (as in a z_stream). The data pointers
439 * are not changed, so the next input is (data+input_size) and the next
440 * available output is (output+output_size).
442 static int
443 png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
444 /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
445 /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
447 if (png_ptr->zowner == owner) /* Else not claimed */
449 int ret;
450 png_alloc_size_t avail_out = *output_size_ptr;
451 png_uint_32 avail_in = *input_size_ptr;
453 /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
454 * can't even necessarily handle 65536 bytes) because the type uInt is
455 * "16 bits or more". Consequently it is necessary to chunk the input to
456 * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
457 * maximum value that can be stored in a uInt.) It is possible to set
458 * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
459 * a performance advantage, because it reduces the amount of data accessed
460 * at each step and that may give the OS more time to page it in.
462 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
463 /* avail_in and avail_out are set below from 'size' */
464 png_ptr->zstream.avail_in = 0;
465 png_ptr->zstream.avail_out = 0;
467 /* Read directly into the output if it is available (this is set to
468 * a local buffer below if output is NULL).
470 if (output != NULL)
471 png_ptr->zstream.next_out = output;
475 uInt avail;
476 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
478 /* zlib INPUT BUFFER */
479 /* The setting of 'avail_in' used to be outside the loop; by setting it
480 * inside it is possible to chunk the input to zlib and simply rely on
481 * zlib to advance the 'next_in' pointer. This allows arbitrary
482 * amounts of data to be passed through zlib at the unavoidable cost of
483 * requiring a window save (memcpy of up to 32768 output bytes)
484 * every ZLIB_IO_MAX input bytes.
486 avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
488 avail = ZLIB_IO_MAX;
490 if (avail_in < avail)
491 avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
493 avail_in -= avail;
494 png_ptr->zstream.avail_in = avail;
496 /* zlib OUTPUT BUFFER */
497 avail_out += png_ptr->zstream.avail_out; /* not written last time */
499 avail = ZLIB_IO_MAX; /* maximum zlib can process */
501 if (output == NULL)
503 /* Reset the output buffer each time round if output is NULL and
504 * make available the full buffer, up to 'remaining_space'
506 png_ptr->zstream.next_out = local_buffer;
507 if ((sizeof local_buffer) < avail)
508 avail = (sizeof local_buffer);
511 if (avail_out < avail)
512 avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
514 png_ptr->zstream.avail_out = avail;
515 avail_out -= avail;
517 /* zlib inflate call */
518 /* In fact 'avail_out' may be 0 at this point, that happens at the end
519 * of the read when the final LZ end code was not passed at the end of
520 * the previous chunk of input data. Tell zlib if we have reached the
521 * end of the output buffer.
523 ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH :
524 (finish ? Z_FINISH : Z_SYNC_FLUSH));
525 } while (ret == Z_OK);
527 /* For safety kill the local buffer pointer now */
528 if (output == NULL)
529 png_ptr->zstream.next_out = NULL;
531 /* Claw back the 'size' and 'remaining_space' byte counts. */
532 avail_in += png_ptr->zstream.avail_in;
533 avail_out += png_ptr->zstream.avail_out;
535 /* Update the input and output sizes; the updated values are the amount
536 * consumed or written, effectively the inverse of what zlib uses.
538 if (avail_out > 0)
539 *output_size_ptr -= avail_out;
541 if (avail_in > 0)
542 *input_size_ptr -= avail_in;
544 /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
545 png_zstream_error(png_ptr, ret);
546 return ret;
549 else
551 /* This is a bad internal error. The recovery assigns to the zstream msg
552 * pointer, which is not owned by the caller, but this is safe; it's only
553 * used on errors!
555 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
556 return Z_STREAM_ERROR;
561 * Decompress trailing data in a chunk. The assumption is that read_buffer
562 * points at an allocated area holding the contents of a chunk with a
563 * trailing compressed part. What we get back is an allocated area
564 * holding the original prefix part and an uncompressed version of the
565 * trailing part (the malloc area passed in is freed).
567 static int
568 png_decompress_chunk(png_structrp png_ptr,
569 png_uint_32 chunklength, png_uint_32 prefix_size,
570 png_alloc_size_t *newlength /* must be initialized to the maximum! */,
571 int terminate /*add a '\0' to the end of the uncompressed data*/)
573 /* TODO: implement different limits for different types of chunk.
575 * The caller supplies *newlength set to the maximum length of the
576 * uncompressed data, but this routine allocates space for the prefix and
577 * maybe a '\0' terminator too. We have to assume that 'prefix_size' is
578 * limited only by the maximum chunk size.
580 png_alloc_size_t limit = PNG_SIZE_MAX;
582 # ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
583 if (png_ptr->user_chunk_malloc_max > 0 &&
584 png_ptr->user_chunk_malloc_max < limit)
585 limit = png_ptr->user_chunk_malloc_max;
586 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
587 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
588 limit = PNG_USER_CHUNK_MALLOC_MAX;
589 # endif
591 if (limit >= prefix_size + (terminate != 0))
593 int ret;
595 limit -= prefix_size + (terminate != 0);
597 if (limit < *newlength)
598 *newlength = limit;
600 /* Now try to claim the stream. */
601 ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
603 if (ret == Z_OK)
605 png_uint_32 lzsize = chunklength - prefix_size;
607 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
608 /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
609 /* output: */ NULL, newlength);
611 if (ret == Z_STREAM_END)
613 /* Use 'inflateReset' here, not 'inflateReset2' because this
614 * preserves the previously decided window size (otherwise it would
615 * be necessary to store the previous window size.) In practice
616 * this doesn't matter anyway, because png_inflate will call inflate
617 * with Z_FINISH in almost all cases, so the window will not be
618 * maintained.
620 if (inflateReset(&png_ptr->zstream) == Z_OK)
622 /* Because of the limit checks above we know that the new,
623 * expanded, size will fit in a size_t (let alone an
624 * png_alloc_size_t). Use png_malloc_base here to avoid an
625 * extra OOM message.
627 png_alloc_size_t new_size = *newlength;
628 png_alloc_size_t buffer_size = prefix_size + new_size +
629 (terminate != 0);
630 png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
631 buffer_size));
633 if (text != NULL)
635 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
636 png_ptr->read_buffer + prefix_size, &lzsize,
637 text + prefix_size, newlength);
639 if (ret == Z_STREAM_END)
641 if (new_size == *newlength)
643 if (terminate)
644 text[prefix_size + *newlength] = 0;
646 if (prefix_size > 0)
647 memcpy(text, png_ptr->read_buffer, prefix_size);
650 png_bytep old_ptr = png_ptr->read_buffer;
652 png_ptr->read_buffer = text;
653 png_ptr->read_buffer_size = buffer_size;
654 text = old_ptr; /* freed below */
658 else
660 /* The size changed on the second read, there can be no
661 * guarantee that anything is correct at this point.
662 * The 'msg' pointer has been set to "unexpected end of
663 * LZ stream", which is fine, but return an error code
664 * that the caller won't accept.
666 ret = PNG_UNEXPECTED_ZLIB_RETURN;
670 else if (ret == Z_OK)
671 ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
673 /* Free the text pointer (this is the old read_buffer on
674 * success)
676 png_free(png_ptr, text);
678 /* This really is very benign, but it's still an error because
679 * the extra space may otherwise be used as a Trojan Horse.
681 if (ret == Z_STREAM_END &&
682 chunklength - prefix_size != lzsize)
683 png_chunk_benign_error(png_ptr, "extra compressed data");
686 else
688 /* Out of memory allocating the buffer */
689 ret = Z_MEM_ERROR;
690 png_zstream_error(png_ptr, Z_MEM_ERROR);
694 else
696 /* inflateReset failed, store the error message */
697 png_zstream_error(png_ptr, ret);
699 if (ret == Z_STREAM_END)
700 ret = PNG_UNEXPECTED_ZLIB_RETURN;
704 else if (ret == Z_OK)
705 ret = PNG_UNEXPECTED_ZLIB_RETURN;
707 /* Release the claimed stream */
708 png_ptr->zowner = 0;
711 else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
712 ret = PNG_UNEXPECTED_ZLIB_RETURN;
714 return ret;
717 else
719 /* Application/configuration limits exceeded */
720 png_zstream_error(png_ptr, Z_MEM_ERROR);
721 return Z_MEM_ERROR;
724 #endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
726 #ifdef PNG_READ_iCCP_SUPPORTED
727 /* Perform a partial read and decompress, producing 'avail_out' bytes and
728 * reading from the current chunk as required.
730 static int
731 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
732 png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
733 int finish)
735 if (png_ptr->zowner == png_ptr->chunk_name)
737 int ret;
739 /* next_in and avail_in must have been initialized by the caller. */
740 png_ptr->zstream.next_out = next_out;
741 png_ptr->zstream.avail_out = 0; /* set in the loop */
745 if (png_ptr->zstream.avail_in == 0)
747 if (read_size > *chunk_bytes)
748 read_size = (uInt)*chunk_bytes;
749 *chunk_bytes -= read_size;
751 if (read_size > 0)
752 png_crc_read(png_ptr, read_buffer, read_size);
754 png_ptr->zstream.next_in = read_buffer;
755 png_ptr->zstream.avail_in = read_size;
758 if (png_ptr->zstream.avail_out == 0)
760 uInt avail = ZLIB_IO_MAX;
761 if (avail > *out_size)
762 avail = (uInt)*out_size;
763 *out_size -= avail;
765 png_ptr->zstream.avail_out = avail;
768 /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
769 * the available output is produced; this allows reading of truncated
770 * streams.
772 ret = inflate(&png_ptr->zstream,
773 *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
775 while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
777 *out_size += png_ptr->zstream.avail_out;
778 png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
780 /* Ensure the error message pointer is always set: */
781 png_zstream_error(png_ptr, ret);
782 return ret;
785 else
787 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
788 return Z_STREAM_ERROR;
791 #endif
793 /* Read and check the IDHR chunk */
794 void /* PRIVATE */
795 png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
797 png_byte buf[13];
798 png_uint_32 width, height;
799 int bit_depth, color_type, compression_type, filter_type;
800 int interlace_type;
802 png_debug(1, "in png_handle_IHDR");
804 if (png_ptr->mode & PNG_HAVE_IHDR)
805 png_chunk_error(png_ptr, "out of place");
807 /* Check the length */
808 if (length != 13)
809 png_chunk_error(png_ptr, "invalid");
811 png_ptr->mode |= PNG_HAVE_IHDR;
813 png_crc_read(png_ptr, buf, 13);
814 png_crc_finish(png_ptr, 0);
816 width = png_get_uint_31(png_ptr, buf);
817 height = png_get_uint_31(png_ptr, buf + 4);
818 bit_depth = buf[8];
819 color_type = buf[9];
820 compression_type = buf[10];
821 filter_type = buf[11];
822 interlace_type = buf[12];
824 /* Set internal variables */
825 png_ptr->width = width;
826 png_ptr->height = height;
827 png_ptr->bit_depth = (png_byte)bit_depth;
828 png_ptr->interlaced = (png_byte)interlace_type;
829 png_ptr->color_type = (png_byte)color_type;
830 #ifdef PNG_MNG_FEATURES_SUPPORTED
831 png_ptr->filter_type = (png_byte)filter_type;
832 #endif
833 png_ptr->compression_type = (png_byte)compression_type;
835 /* Find number of channels */
836 switch (png_ptr->color_type)
838 default: /* invalid, png_set_IHDR calls png_error */
839 case PNG_COLOR_TYPE_GRAY:
840 case PNG_COLOR_TYPE_PALETTE:
841 png_ptr->channels = 1;
842 break;
844 case PNG_COLOR_TYPE_RGB:
845 png_ptr->channels = 3;
846 break;
848 case PNG_COLOR_TYPE_GRAY_ALPHA:
849 png_ptr->channels = 2;
850 break;
852 case PNG_COLOR_TYPE_RGB_ALPHA:
853 png_ptr->channels = 4;
854 break;
857 /* Set up other useful info */
858 png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
859 png_ptr->channels);
860 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
861 png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
862 png_debug1(3, "channels = %d", png_ptr->channels);
863 png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
864 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
865 color_type, interlace_type, compression_type, filter_type);
868 /* Read and check the palette */
869 void /* PRIVATE */
870 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
872 png_color palette[PNG_MAX_PALETTE_LENGTH];
873 int num, i;
874 #ifdef PNG_POINTER_INDEXING_SUPPORTED
875 png_colorp pal_ptr;
876 #endif
878 png_debug(1, "in png_handle_PLTE");
880 if (!(png_ptr->mode & PNG_HAVE_IHDR))
881 png_chunk_error(png_ptr, "missing IHDR");
883 /* Moved to before the 'after IDAT' check below because otherwise duplicate
884 * PLTE chunks are potentially ignored (the spec says there shall not be more
885 * than one PLTE, the error is not treated as benign, so this check trumps
886 * the requirement that PLTE appears before IDAT.)
888 else if (png_ptr->mode & PNG_HAVE_PLTE)
889 png_chunk_error(png_ptr, "duplicate");
891 else if (png_ptr->mode & PNG_HAVE_IDAT)
893 /* This is benign because the non-benign error happened before, when an
894 * IDAT was encountered in a color-mapped image with no PLTE.
896 png_crc_finish(png_ptr, length);
897 png_chunk_benign_error(png_ptr, "out of place");
898 return;
901 png_ptr->mode |= PNG_HAVE_PLTE;
903 if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
905 png_crc_finish(png_ptr, length);
906 png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
907 return;
910 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
911 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
913 png_crc_finish(png_ptr, length);
914 return;
916 #endif
918 if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
920 png_crc_finish(png_ptr, length);
922 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
923 png_chunk_benign_error(png_ptr, "invalid");
925 else
926 png_chunk_error(png_ptr, "invalid");
928 return;
931 /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
932 num = (int)length / 3;
934 #ifdef PNG_POINTER_INDEXING_SUPPORTED
935 for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
937 png_byte buf[3];
939 png_crc_read(png_ptr, buf, 3);
940 pal_ptr->red = buf[0];
941 pal_ptr->green = buf[1];
942 pal_ptr->blue = buf[2];
944 #else
945 for (i = 0; i < num; i++)
947 png_byte buf[3];
949 png_crc_read(png_ptr, buf, 3);
950 /* Don't depend upon png_color being any order */
951 palette[i].red = buf[0];
952 palette[i].green = buf[1];
953 palette[i].blue = buf[2];
955 #endif
957 /* If we actually need the PLTE chunk (ie for a paletted image), we do
958 * whatever the normal CRC configuration tells us. However, if we
959 * have an RGB image, the PLTE can be considered ancillary, so
960 * we will act as though it is.
962 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
963 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
964 #endif
966 png_crc_finish(png_ptr, 0);
969 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
970 else if (png_crc_error(png_ptr)) /* Only if we have a CRC error */
972 /* If we don't want to use the data from an ancillary chunk,
973 * we have two options: an error abort, or a warning and we
974 * ignore the data in this chunk (which should be OK, since
975 * it's considered ancillary for a RGB or RGBA image).
977 * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
978 * chunk type to determine whether to check the ancillary or the critical
979 * flags.
981 if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
983 if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
985 png_chunk_benign_error(png_ptr, "CRC error");
988 else
990 png_chunk_warning(png_ptr, "CRC error");
991 return;
995 /* Otherwise, we (optionally) emit a warning and use the chunk. */
996 else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
998 png_chunk_warning(png_ptr, "CRC error");
1001 #endif
1003 /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
1004 * own copy of the palette. This has the side effect that when png_start_row
1005 * is called (this happens after any call to png_read_update_info) the
1006 * info_ptr palette gets changed. This is extremely unexpected and
1007 * confusing.
1009 * Fix this by not sharing the palette in this way.
1011 png_set_PLTE(png_ptr, info_ptr, palette, num);
1013 /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
1014 * IDAT. Prior to 1.6.0 this was not checked; instead the code merely
1015 * checked the apparent validity of a tRNS chunk inserted before PLTE on a
1016 * palette PNG. 1.6.0 attempts to rigorously follow the standard and
1017 * therefore does a benign error if the erroneous condition is detected *and*
1018 * cancels the tRNS if the benign error returns. The alternative is to
1019 * amend the standard since it would be rather hypocritical of the standards
1020 * maintainers to ignore it.
1022 #ifdef PNG_READ_tRNS_SUPPORTED
1023 if (png_ptr->num_trans > 0 ||
1024 (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
1026 /* Cancel this because otherwise it would be used if the transforms
1027 * require it. Don't cancel the 'valid' flag because this would prevent
1028 * detection of duplicate chunks.
1030 png_ptr->num_trans = 0;
1032 if (info_ptr != NULL)
1033 info_ptr->num_trans = 0;
1035 png_chunk_benign_error(png_ptr, "tRNS must be after");
1037 #endif
1039 #ifdef PNG_READ_hIST_SUPPORTED
1040 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
1041 png_chunk_benign_error(png_ptr, "hIST must be after");
1042 #endif
1044 #ifdef PNG_READ_bKGD_SUPPORTED
1045 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1046 png_chunk_benign_error(png_ptr, "bKGD must be after");
1047 #endif
1050 void /* PRIVATE */
1051 png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1053 png_debug(1, "in png_handle_IEND");
1055 if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
1056 png_chunk_error(png_ptr, "out of place");
1058 png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
1060 png_crc_finish(png_ptr, length);
1062 if (length != 0)
1063 png_chunk_benign_error(png_ptr, "invalid");
1065 PNG_UNUSED(info_ptr)
1068 #ifdef PNG_READ_gAMA_SUPPORTED
1069 void /* PRIVATE */
1070 png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1072 png_fixed_point igamma;
1073 png_byte buf[4];
1075 png_debug(1, "in png_handle_gAMA");
1077 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1078 png_chunk_error(png_ptr, "missing IHDR");
1080 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1082 png_crc_finish(png_ptr, length);
1083 png_chunk_benign_error(png_ptr, "out of place");
1084 return;
1087 if (length != 4)
1089 png_crc_finish(png_ptr, length);
1090 png_chunk_benign_error(png_ptr, "invalid");
1091 return;
1094 png_crc_read(png_ptr, buf, 4);
1096 if (png_crc_finish(png_ptr, 0))
1097 return;
1099 igamma = png_get_fixed_point(NULL, buf);
1101 png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
1102 png_colorspace_sync(png_ptr, info_ptr);
1104 #endif
1106 #ifdef PNG_READ_sBIT_SUPPORTED
1107 void /* PRIVATE */
1108 png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1110 unsigned int truelen;
1111 png_byte buf[4];
1113 png_debug(1, "in png_handle_sBIT");
1115 buf[0] = buf[1] = buf[2] = buf[3] = 0;
1117 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1118 png_chunk_error(png_ptr, "missing IHDR");
1120 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1122 png_crc_finish(png_ptr, length);
1123 png_chunk_benign_error(png_ptr, "out of place");
1124 return;
1127 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
1129 png_crc_finish(png_ptr, length);
1130 png_chunk_benign_error(png_ptr, "duplicate");
1131 return;
1134 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1135 truelen = 3;
1137 else
1138 truelen = png_ptr->channels;
1140 if (length != truelen || length > 4)
1142 png_chunk_benign_error(png_ptr, "invalid");
1143 png_crc_finish(png_ptr, length);
1144 return;
1147 png_crc_read(png_ptr, buf, truelen);
1149 if (png_crc_finish(png_ptr, 0))
1150 return;
1152 if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
1154 png_ptr->sig_bit.red = buf[0];
1155 png_ptr->sig_bit.green = buf[1];
1156 png_ptr->sig_bit.blue = buf[2];
1157 png_ptr->sig_bit.alpha = buf[3];
1160 else
1162 png_ptr->sig_bit.gray = buf[0];
1163 png_ptr->sig_bit.red = buf[0];
1164 png_ptr->sig_bit.green = buf[0];
1165 png_ptr->sig_bit.blue = buf[0];
1166 png_ptr->sig_bit.alpha = buf[1];
1169 png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
1171 #endif
1173 #ifdef PNG_READ_cHRM_SUPPORTED
1174 void /* PRIVATE */
1175 png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1177 png_byte buf[32];
1178 png_xy xy;
1180 png_debug(1, "in png_handle_cHRM");
1182 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1183 png_chunk_error(png_ptr, "missing IHDR");
1185 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1187 png_crc_finish(png_ptr, length);
1188 png_chunk_benign_error(png_ptr, "out of place");
1189 return;
1192 if (length != 32)
1194 png_crc_finish(png_ptr, length);
1195 png_chunk_benign_error(png_ptr, "invalid");
1196 return;
1199 png_crc_read(png_ptr, buf, 32);
1201 if (png_crc_finish(png_ptr, 0))
1202 return;
1204 xy.whitex = png_get_fixed_point(NULL, buf);
1205 xy.whitey = png_get_fixed_point(NULL, buf + 4);
1206 xy.redx = png_get_fixed_point(NULL, buf + 8);
1207 xy.redy = png_get_fixed_point(NULL, buf + 12);
1208 xy.greenx = png_get_fixed_point(NULL, buf + 16);
1209 xy.greeny = png_get_fixed_point(NULL, buf + 20);
1210 xy.bluex = png_get_fixed_point(NULL, buf + 24);
1211 xy.bluey = png_get_fixed_point(NULL, buf + 28);
1213 if (xy.whitex == PNG_FIXED_ERROR ||
1214 xy.whitey == PNG_FIXED_ERROR ||
1215 xy.redx == PNG_FIXED_ERROR ||
1216 xy.redy == PNG_FIXED_ERROR ||
1217 xy.greenx == PNG_FIXED_ERROR ||
1218 xy.greeny == PNG_FIXED_ERROR ||
1219 xy.bluex == PNG_FIXED_ERROR ||
1220 xy.bluey == PNG_FIXED_ERROR)
1222 png_chunk_benign_error(png_ptr, "invalid values");
1223 return;
1226 /* If a colorspace error has already been output skip this chunk */
1227 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1228 return;
1230 if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM)
1232 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1233 png_colorspace_sync(png_ptr, info_ptr);
1234 png_chunk_benign_error(png_ptr, "duplicate");
1235 return;
1238 png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
1239 (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1240 1/*prefer cHRM values*/);
1241 png_colorspace_sync(png_ptr, info_ptr);
1243 #endif
1245 #ifdef PNG_READ_sRGB_SUPPORTED
1246 void /* PRIVATE */
1247 png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1249 png_byte intent;
1251 png_debug(1, "in png_handle_sRGB");
1253 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1254 png_chunk_error(png_ptr, "missing IHDR");
1256 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1258 png_crc_finish(png_ptr, length);
1259 png_chunk_benign_error(png_ptr, "out of place");
1260 return;
1263 if (length != 1)
1265 png_crc_finish(png_ptr, length);
1266 png_chunk_benign_error(png_ptr, "invalid");
1267 return;
1270 png_crc_read(png_ptr, &intent, 1);
1272 if (png_crc_finish(png_ptr, 0))
1273 return;
1275 /* If a colorspace error has already been output skip this chunk */
1276 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1277 return;
1279 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1280 * this.
1282 if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT)
1284 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1285 png_colorspace_sync(png_ptr, info_ptr);
1286 png_chunk_benign_error(png_ptr, "too many profiles");
1287 return;
1290 (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
1291 png_colorspace_sync(png_ptr, info_ptr);
1293 #endif /* PNG_READ_sRGB_SUPPORTED */
1295 #ifdef PNG_READ_iCCP_SUPPORTED
1296 void /* PRIVATE */
1297 png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1298 /* Note: this does not properly handle profiles that are > 64K under DOS */
1300 png_const_charp errmsg = NULL; /* error message output, or no error */
1301 int finished = 0; /* crc checked */
1303 png_debug(1, "in png_handle_iCCP");
1305 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1306 png_chunk_error(png_ptr, "missing IHDR");
1308 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1310 png_crc_finish(png_ptr, length);
1311 png_chunk_benign_error(png_ptr, "out of place");
1312 return;
1315 /* Consistent with all the above colorspace handling an obviously *invalid*
1316 * chunk is just ignored, so does not invalidate the color space. An
1317 * alternative is to set the 'invalid' flags at the start of this routine
1318 * and only clear them in they were not set before and all the tests pass.
1319 * The minimum 'deflate' stream is assumed to be just the 2 byte header and 4
1320 * byte checksum. The keyword must be one character and there is a
1321 * terminator (0) byte and the compression method.
1323 if (length < 9)
1325 png_crc_finish(png_ptr, length);
1326 png_chunk_benign_error(png_ptr, "too short");
1327 return;
1330 /* If a colorspace error has already been output skip this chunk */
1331 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1333 png_crc_finish(png_ptr, length);
1334 return;
1337 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1338 * this.
1340 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
1342 uInt read_length, keyword_length;
1343 char keyword[81];
1345 /* Find the keyword; the keyword plus separator and compression method
1346 * bytes can be at most 81 characters long.
1348 read_length = 81; /* maximum */
1349 if (read_length > length)
1350 read_length = (uInt)length;
1352 png_crc_read(png_ptr, (png_bytep)keyword, read_length);
1353 length -= read_length;
1355 keyword_length = 0;
1356 while (keyword_length < 80 && keyword_length < read_length &&
1357 keyword[keyword_length] != 0)
1358 ++keyword_length;
1360 /* TODO: make the keyword checking common */
1361 if (keyword_length >= 1 && keyword_length <= 79)
1363 /* We only understand '0' compression - deflate - so if we get a
1364 * different value we can't safely decode the chunk.
1366 if (keyword_length+1 < read_length &&
1367 keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
1369 read_length -= keyword_length+2;
1371 if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
1373 Byte profile_header[132];
1374 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
1375 png_alloc_size_t size = (sizeof profile_header);
1377 png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
1378 png_ptr->zstream.avail_in = read_length;
1379 (void)png_inflate_read(png_ptr, local_buffer,
1380 (sizeof local_buffer), &length, profile_header, &size,
1381 0/*finish: don't, because the output is too small*/);
1383 if (size == 0)
1385 /* We have the ICC profile header; do the basic header checks.
1387 const png_uint_32 profile_length =
1388 png_get_uint_32(profile_header);
1390 if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
1391 keyword, profile_length))
1393 /* The length is apparently ok, so we can check the 132
1394 * byte header.
1396 if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
1397 keyword, profile_length, profile_header,
1398 png_ptr->color_type))
1400 /* Now read the tag table; a variable size buffer is
1401 * needed at this point, allocate one for the whole
1402 * profile. The header check has already validated
1403 * that none of these stuff will overflow.
1405 const png_uint_32 tag_count = png_get_uint_32(
1406 profile_header+128);
1407 png_bytep profile = png_read_buffer(png_ptr,
1408 profile_length, 2/*silent*/);
1410 if (profile != NULL)
1412 memcpy(profile, profile_header,
1413 (sizeof profile_header));
1415 size = 12 * tag_count;
1417 (void)png_inflate_read(png_ptr, local_buffer,
1418 (sizeof local_buffer), &length,
1419 profile + (sizeof profile_header), &size, 0);
1421 /* Still expect a a buffer error because we expect
1422 * there to be some tag data!
1424 if (size == 0)
1426 if (png_icc_check_tag_table(png_ptr,
1427 &png_ptr->colorspace, keyword, profile_length,
1428 profile))
1430 /* The profile has been validated for basic
1431 * security issues, so read the whole thing in.
1433 size = profile_length - (sizeof profile_header)
1434 - 12 * tag_count;
1436 (void)png_inflate_read(png_ptr, local_buffer,
1437 (sizeof local_buffer), &length,
1438 profile + (sizeof profile_header) +
1439 12 * tag_count, &size, 1/*finish*/);
1441 if (length > 0 && !(png_ptr->flags &
1442 PNG_FLAG_BENIGN_ERRORS_WARN))
1443 errmsg = "extra compressed data";
1445 /* But otherwise allow extra data: */
1446 else if (size == 0)
1448 if (length > 0)
1450 /* This can be handled completely, so
1451 * keep going.
1453 png_chunk_warning(png_ptr,
1454 "extra compressed data");
1457 png_crc_finish(png_ptr, length);
1458 finished = 1;
1460 # ifdef PNG_sRGB_SUPPORTED
1461 /* Check for a match against sRGB */
1462 png_icc_set_sRGB(png_ptr,
1463 &png_ptr->colorspace, profile,
1464 png_ptr->zstream.adler);
1465 # endif
1467 /* Steal the profile for info_ptr. */
1468 if (info_ptr != NULL)
1470 png_free_data(png_ptr, info_ptr,
1471 PNG_FREE_ICCP, 0);
1473 info_ptr->iccp_name = png_voidcast(char*,
1474 png_malloc_base(png_ptr,
1475 keyword_length+1));
1476 if (info_ptr->iccp_name != NULL)
1478 memcpy(info_ptr->iccp_name, keyword,
1479 keyword_length+1);
1480 info_ptr->iccp_proflen =
1481 profile_length;
1482 info_ptr->iccp_profile = profile;
1483 png_ptr->read_buffer = NULL; /*steal*/
1484 info_ptr->free_me |= PNG_FREE_ICCP;
1485 info_ptr->valid |= PNG_INFO_iCCP;
1488 else
1490 png_ptr->colorspace.flags |=
1491 PNG_COLORSPACE_INVALID;
1492 errmsg = "out of memory";
1496 /* else the profile remains in the read
1497 * buffer which gets reused for subsequent
1498 * chunks.
1501 if (info_ptr != NULL)
1502 png_colorspace_sync(png_ptr, info_ptr);
1504 if (errmsg == NULL)
1506 png_ptr->zowner = 0;
1507 return;
1511 else if (size > 0)
1512 errmsg = "truncated";
1514 else
1515 errmsg = png_ptr->zstream.msg;
1518 /* else png_icc_check_tag_table output an error */
1521 else /* profile truncated */
1522 errmsg = png_ptr->zstream.msg;
1525 else
1526 errmsg = "out of memory";
1529 /* else png_icc_check_header output an error */
1532 /* else png_icc_check_length output an error */
1535 else /* profile truncated */
1536 errmsg = png_ptr->zstream.msg;
1538 /* Release the stream */
1539 png_ptr->zowner = 0;
1542 else /* png_inflate_claim failed */
1543 errmsg = png_ptr->zstream.msg;
1546 else
1547 errmsg = "bad compression method"; /* or missing */
1550 else
1551 errmsg = "bad keyword";
1554 else
1555 errmsg = "too many profiles";
1557 /* Failure: the reason is in 'errmsg' */
1558 if (!finished)
1559 png_crc_finish(png_ptr, length);
1561 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1562 png_colorspace_sync(png_ptr, info_ptr);
1563 if (errmsg != NULL) /* else already output */
1564 png_chunk_benign_error(png_ptr, errmsg);
1566 #endif /* PNG_READ_iCCP_SUPPORTED */
1568 #ifdef PNG_READ_sPLT_SUPPORTED
1569 void /* PRIVATE */
1570 png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1571 /* Note: this does not properly handle chunks that are > 64K under DOS */
1573 png_bytep entry_start, buffer;
1574 png_sPLT_t new_palette;
1575 png_sPLT_entryp pp;
1576 png_uint_32 data_length;
1577 int entry_size, i;
1578 png_uint_32 skip = 0;
1579 png_uint_32 dl;
1580 png_size_t max_dl;
1582 png_debug(1, "in png_handle_sPLT");
1584 #ifdef PNG_USER_LIMITS_SUPPORTED
1585 if (png_ptr->user_chunk_cache_max != 0)
1587 if (png_ptr->user_chunk_cache_max == 1)
1589 png_crc_finish(png_ptr, length);
1590 return;
1593 if (--png_ptr->user_chunk_cache_max == 1)
1595 png_warning(png_ptr, "No space in chunk cache for sPLT");
1596 png_crc_finish(png_ptr, length);
1597 return;
1600 #endif
1602 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1603 png_chunk_error(png_ptr, "missing IHDR");
1605 else if (png_ptr->mode & PNG_HAVE_IDAT)
1607 png_crc_finish(png_ptr, length);
1608 png_chunk_benign_error(png_ptr, "out of place");
1609 return;
1612 #ifdef PNG_MAX_MALLOC_64K
1613 if (length > 65535U)
1615 png_crc_finish(png_ptr, length);
1616 png_chunk_benign_error(png_ptr, "too large to fit in memory");
1617 return;
1619 #endif
1621 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
1622 if (buffer == NULL)
1624 png_crc_finish(png_ptr, length);
1625 png_chunk_benign_error(png_ptr, "out of memory");
1626 return;
1630 /* WARNING: this may break if size_t is less than 32 bits; it is assumed
1631 * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
1632 * potential breakage point if the types in pngconf.h aren't exactly right.
1634 png_crc_read(png_ptr, buffer, length);
1636 if (png_crc_finish(png_ptr, skip))
1637 return;
1639 buffer[length] = 0;
1641 for (entry_start = buffer; *entry_start; entry_start++)
1642 /* Empty loop to find end of name */ ;
1644 ++entry_start;
1646 /* A sample depth should follow the separator, and we should be on it */
1647 if (entry_start > buffer + length - 2)
1649 png_warning(png_ptr, "malformed sPLT chunk");
1650 return;
1653 new_palette.depth = *entry_start++;
1654 entry_size = (new_palette.depth == 8 ? 6 : 10);
1655 /* This must fit in a png_uint_32 because it is derived from the original
1656 * chunk data length.
1658 data_length = length - (png_uint_32)(entry_start - buffer);
1660 /* Integrity-check the data length */
1661 if (data_length % entry_size)
1663 png_warning(png_ptr, "sPLT chunk has bad length");
1664 return;
1667 dl = (png_int_32)(data_length / entry_size);
1668 max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
1670 if (dl > max_dl)
1672 png_warning(png_ptr, "sPLT chunk too long");
1673 return;
1676 new_palette.nentries = (png_int_32)(data_length / entry_size);
1678 new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
1679 png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
1681 if (new_palette.entries == NULL)
1683 png_warning(png_ptr, "sPLT chunk requires too much memory");
1684 return;
1687 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1688 for (i = 0; i < new_palette.nentries; i++)
1690 pp = new_palette.entries + i;
1692 if (new_palette.depth == 8)
1694 pp->red = *entry_start++;
1695 pp->green = *entry_start++;
1696 pp->blue = *entry_start++;
1697 pp->alpha = *entry_start++;
1700 else
1702 pp->red = png_get_uint_16(entry_start); entry_start += 2;
1703 pp->green = png_get_uint_16(entry_start); entry_start += 2;
1704 pp->blue = png_get_uint_16(entry_start); entry_start += 2;
1705 pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
1708 pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
1710 #else
1711 pp = new_palette.entries;
1713 for (i = 0; i < new_palette.nentries; i++)
1716 if (new_palette.depth == 8)
1718 pp[i].red = *entry_start++;
1719 pp[i].green = *entry_start++;
1720 pp[i].blue = *entry_start++;
1721 pp[i].alpha = *entry_start++;
1724 else
1726 pp[i].red = png_get_uint_16(entry_start); entry_start += 2;
1727 pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
1728 pp[i].blue = png_get_uint_16(entry_start); entry_start += 2;
1729 pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
1732 pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
1734 #endif
1736 /* Discard all chunk data except the name and stash that */
1737 new_palette.name = (png_charp)buffer;
1739 png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
1741 png_free(png_ptr, new_palette.entries);
1743 #endif /* PNG_READ_sPLT_SUPPORTED */
1745 #ifdef PNG_READ_tRNS_SUPPORTED
1746 void /* PRIVATE */
1747 png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1749 png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
1751 png_debug(1, "in png_handle_tRNS");
1753 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1754 png_chunk_error(png_ptr, "missing IHDR");
1756 else if (png_ptr->mode & PNG_HAVE_IDAT)
1758 png_crc_finish(png_ptr, length);
1759 png_chunk_benign_error(png_ptr, "out of place");
1760 return;
1763 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
1765 png_crc_finish(png_ptr, length);
1766 png_chunk_benign_error(png_ptr, "duplicate");
1767 return;
1770 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
1772 png_byte buf[2];
1774 if (length != 2)
1776 png_crc_finish(png_ptr, length);
1777 png_chunk_benign_error(png_ptr, "invalid");
1778 return;
1781 png_crc_read(png_ptr, buf, 2);
1782 png_ptr->num_trans = 1;
1783 png_ptr->trans_color.gray = png_get_uint_16(buf);
1786 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
1788 png_byte buf[6];
1790 if (length != 6)
1792 png_crc_finish(png_ptr, length);
1793 png_chunk_benign_error(png_ptr, "invalid");
1794 return;
1797 png_crc_read(png_ptr, buf, length);
1798 png_ptr->num_trans = 1;
1799 png_ptr->trans_color.red = png_get_uint_16(buf);
1800 png_ptr->trans_color.green = png_get_uint_16(buf + 2);
1801 png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
1804 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1806 if (!(png_ptr->mode & PNG_HAVE_PLTE))
1808 /* TODO: is this actually an error in the ISO spec? */
1809 png_crc_finish(png_ptr, length);
1810 png_chunk_benign_error(png_ptr, "out of place");
1811 return;
1814 if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH ||
1815 length == 0)
1817 png_crc_finish(png_ptr, length);
1818 png_chunk_benign_error(png_ptr, "invalid");
1819 return;
1822 png_crc_read(png_ptr, readbuf, length);
1823 png_ptr->num_trans = (png_uint_16)length;
1826 else
1828 png_crc_finish(png_ptr, length);
1829 png_chunk_benign_error(png_ptr, "invalid with alpha channel");
1830 return;
1833 if (png_crc_finish(png_ptr, 0))
1835 png_ptr->num_trans = 0;
1836 return;
1839 /* TODO: this is a horrible side effect in the palette case because the
1840 * png_struct ends up with a pointer to the tRNS buffer owned by the
1841 * png_info. Fix this.
1843 png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
1844 &(png_ptr->trans_color));
1846 #endif
1848 #ifdef PNG_READ_bKGD_SUPPORTED
1849 void /* PRIVATE */
1850 png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1852 unsigned int truelen;
1853 png_byte buf[6];
1854 png_color_16 background;
1856 png_debug(1, "in png_handle_bKGD");
1858 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1859 png_chunk_error(png_ptr, "missing IHDR");
1861 else if ((png_ptr->mode & PNG_HAVE_IDAT) ||
1862 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
1863 !(png_ptr->mode & PNG_HAVE_PLTE)))
1865 png_crc_finish(png_ptr, length);
1866 png_chunk_benign_error(png_ptr, "out of place");
1867 return;
1870 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
1872 png_crc_finish(png_ptr, length);
1873 png_chunk_benign_error(png_ptr, "duplicate");
1874 return;
1877 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1878 truelen = 1;
1880 else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
1881 truelen = 6;
1883 else
1884 truelen = 2;
1886 if (length != truelen)
1888 png_crc_finish(png_ptr, length);
1889 png_chunk_benign_error(png_ptr, "invalid");
1890 return;
1893 png_crc_read(png_ptr, buf, truelen);
1895 if (png_crc_finish(png_ptr, 0))
1896 return;
1898 /* We convert the index value into RGB components so that we can allow
1899 * arbitrary RGB values for background when we have transparency, and
1900 * so it is easy to determine the RGB values of the background color
1901 * from the info_ptr struct.
1903 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1905 background.index = buf[0];
1907 if (info_ptr && info_ptr->num_palette)
1909 if (buf[0] >= info_ptr->num_palette)
1911 png_chunk_benign_error(png_ptr, "invalid index");
1912 return;
1915 background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
1916 background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
1917 background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
1920 else
1921 background.red = background.green = background.blue = 0;
1923 background.gray = 0;
1926 else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
1928 background.index = 0;
1929 background.red =
1930 background.green =
1931 background.blue =
1932 background.gray = png_get_uint_16(buf);
1935 else
1937 background.index = 0;
1938 background.red = png_get_uint_16(buf);
1939 background.green = png_get_uint_16(buf + 2);
1940 background.blue = png_get_uint_16(buf + 4);
1941 background.gray = 0;
1944 png_set_bKGD(png_ptr, info_ptr, &background);
1946 #endif
1948 #ifdef PNG_READ_hIST_SUPPORTED
1949 void /* PRIVATE */
1950 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1952 unsigned int num, i;
1953 png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
1955 png_debug(1, "in png_handle_hIST");
1957 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1958 png_chunk_error(png_ptr, "missing IHDR");
1960 else if ((png_ptr->mode & PNG_HAVE_IDAT) || !(png_ptr->mode & PNG_HAVE_PLTE))
1962 png_crc_finish(png_ptr, length);
1963 png_chunk_benign_error(png_ptr, "out of place");
1964 return;
1967 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
1969 png_crc_finish(png_ptr, length);
1970 png_chunk_benign_error(png_ptr, "duplicate");
1971 return;
1974 num = length / 2 ;
1976 if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH)
1978 png_crc_finish(png_ptr, length);
1979 png_chunk_benign_error(png_ptr, "invalid");
1980 return;
1983 for (i = 0; i < num; i++)
1985 png_byte buf[2];
1987 png_crc_read(png_ptr, buf, 2);
1988 readbuf[i] = png_get_uint_16(buf);
1991 if (png_crc_finish(png_ptr, 0))
1992 return;
1994 png_set_hIST(png_ptr, info_ptr, readbuf);
1996 #endif
1998 #ifdef PNG_READ_pHYs_SUPPORTED
1999 void /* PRIVATE */
2000 png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2002 png_byte buf[9];
2003 png_uint_32 res_x, res_y;
2004 int unit_type;
2006 png_debug(1, "in png_handle_pHYs");
2008 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2009 png_chunk_error(png_ptr, "missing IHDR");
2011 else if (png_ptr->mode & PNG_HAVE_IDAT)
2013 png_crc_finish(png_ptr, length);
2014 png_chunk_benign_error(png_ptr, "out of place");
2015 return;
2018 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
2020 png_crc_finish(png_ptr, length);
2021 png_chunk_benign_error(png_ptr, "duplicate");
2022 return;
2025 if (length != 9)
2027 png_crc_finish(png_ptr, length);
2028 png_chunk_benign_error(png_ptr, "invalid");
2029 return;
2032 png_crc_read(png_ptr, buf, 9);
2034 if (png_crc_finish(png_ptr, 0))
2035 return;
2037 res_x = png_get_uint_32(buf);
2038 res_y = png_get_uint_32(buf + 4);
2039 unit_type = buf[8];
2040 png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
2042 #endif
2044 #ifdef PNG_READ_oFFs_SUPPORTED
2045 void /* PRIVATE */
2046 png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2048 png_byte buf[9];
2049 png_int_32 offset_x, offset_y;
2050 int unit_type;
2052 png_debug(1, "in png_handle_oFFs");
2054 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2055 png_chunk_error(png_ptr, "missing IHDR");
2057 else if (png_ptr->mode & PNG_HAVE_IDAT)
2059 png_crc_finish(png_ptr, length);
2060 png_chunk_benign_error(png_ptr, "out of place");
2061 return;
2064 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
2066 png_crc_finish(png_ptr, length);
2067 png_chunk_benign_error(png_ptr, "duplicate");
2068 return;
2071 if (length != 9)
2073 png_crc_finish(png_ptr, length);
2074 png_chunk_benign_error(png_ptr, "invalid");
2075 return;
2078 png_crc_read(png_ptr, buf, 9);
2080 if (png_crc_finish(png_ptr, 0))
2081 return;
2083 offset_x = png_get_int_32(buf);
2084 offset_y = png_get_int_32(buf + 4);
2085 unit_type = buf[8];
2086 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
2088 #endif
2090 #ifdef PNG_READ_pCAL_SUPPORTED
2091 /* Read the pCAL chunk (described in the PNG Extensions document) */
2092 void /* PRIVATE */
2093 png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2095 png_int_32 X0, X1;
2096 png_byte type, nparams;
2097 png_bytep buffer, buf, units, endptr;
2098 png_charpp params;
2099 int i;
2101 png_debug(1, "in png_handle_pCAL");
2103 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2104 png_chunk_error(png_ptr, "missing IHDR");
2106 else if (png_ptr->mode & PNG_HAVE_IDAT)
2108 png_crc_finish(png_ptr, length);
2109 png_chunk_benign_error(png_ptr, "out of place");
2110 return;
2113 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
2115 png_crc_finish(png_ptr, length);
2116 png_chunk_benign_error(png_ptr, "duplicate");
2117 return;
2120 png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
2121 length + 1);
2123 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2125 if (buffer == NULL)
2127 png_crc_finish(png_ptr, length);
2128 png_chunk_benign_error(png_ptr, "out of memory");
2129 return;
2132 png_crc_read(png_ptr, buffer, length);
2134 if (png_crc_finish(png_ptr, 0))
2135 return;
2137 buffer[length] = 0; /* Null terminate the last string */
2139 png_debug(3, "Finding end of pCAL purpose string");
2140 for (buf = buffer; *buf; buf++)
2141 /* Empty loop */ ;
2143 endptr = buffer + length;
2145 /* We need to have at least 12 bytes after the purpose string
2146 * in order to get the parameter information.
2148 if (endptr <= buf + 12)
2150 png_chunk_benign_error(png_ptr, "invalid");
2151 return;
2154 png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
2155 X0 = png_get_int_32((png_bytep)buf+1);
2156 X1 = png_get_int_32((png_bytep)buf+5);
2157 type = buf[9];
2158 nparams = buf[10];
2159 units = buf + 11;
2161 png_debug(3, "Checking pCAL equation type and number of parameters");
2162 /* Check that we have the right number of parameters for known
2163 * equation types.
2165 if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
2166 (type == PNG_EQUATION_BASE_E && nparams != 3) ||
2167 (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
2168 (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
2170 png_chunk_benign_error(png_ptr, "invalid parameter count");
2171 return;
2174 else if (type >= PNG_EQUATION_LAST)
2176 png_chunk_benign_error(png_ptr, "unrecognized equation type");
2179 for (buf = units; *buf; buf++)
2180 /* Empty loop to move past the units string. */ ;
2182 png_debug(3, "Allocating pCAL parameters array");
2184 params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
2185 nparams * (sizeof (png_charp))));
2187 if (params == NULL)
2189 png_chunk_benign_error(png_ptr, "out of memory");
2190 return;
2193 /* Get pointers to the start of each parameter string. */
2194 for (i = 0; i < nparams; i++)
2196 buf++; /* Skip the null string terminator from previous parameter. */
2198 png_debug1(3, "Reading pCAL parameter %d", i);
2200 for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
2201 /* Empty loop to move past each parameter string */ ;
2203 /* Make sure we haven't run out of data yet */
2204 if (buf > endptr)
2206 png_free(png_ptr, params);
2207 png_chunk_benign_error(png_ptr, "invalid data");
2208 return;
2212 png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
2213 (png_charp)units, params);
2215 png_free(png_ptr, params);
2217 #endif
2219 #ifdef PNG_READ_sCAL_SUPPORTED
2220 /* Read the sCAL chunk */
2221 void /* PRIVATE */
2222 png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2224 png_bytep buffer;
2225 png_size_t i;
2226 int state;
2228 png_debug(1, "in png_handle_sCAL");
2230 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2231 png_chunk_error(png_ptr, "missing IHDR");
2233 else if (png_ptr->mode & PNG_HAVE_IDAT)
2235 png_crc_finish(png_ptr, length);
2236 png_chunk_benign_error(png_ptr, "out of place");
2237 return;
2240 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
2242 png_crc_finish(png_ptr, length);
2243 png_chunk_benign_error(png_ptr, "duplicate");
2244 return;
2247 /* Need unit type, width, \0, height: minimum 4 bytes */
2248 else if (length < 4)
2250 png_crc_finish(png_ptr, length);
2251 png_chunk_benign_error(png_ptr, "invalid");
2252 return;
2255 png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
2256 length + 1);
2258 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2260 if (buffer == NULL)
2262 png_chunk_benign_error(png_ptr, "out of memory");
2263 png_crc_finish(png_ptr, length);
2264 return;
2267 png_crc_read(png_ptr, buffer, length);
2268 buffer[length] = 0; /* Null terminate the last string */
2270 if (png_crc_finish(png_ptr, 0))
2271 return;
2273 /* Validate the unit. */
2274 if (buffer[0] != 1 && buffer[0] != 2)
2276 png_chunk_benign_error(png_ptr, "invalid unit");
2277 return;
2280 /* Validate the ASCII numbers, need two ASCII numbers separated by
2281 * a '\0' and they need to fit exactly in the chunk data.
2283 i = 1;
2284 state = 0;
2286 if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
2287 i >= length || buffer[i++] != 0)
2288 png_chunk_benign_error(png_ptr, "bad width format");
2290 else if (!PNG_FP_IS_POSITIVE(state))
2291 png_chunk_benign_error(png_ptr, "non-positive width");
2293 else
2295 png_size_t heighti = i;
2297 state = 0;
2298 if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
2299 i != length)
2300 png_chunk_benign_error(png_ptr, "bad height format");
2302 else if (!PNG_FP_IS_POSITIVE(state))
2303 png_chunk_benign_error(png_ptr, "non-positive height");
2305 else
2306 /* This is the (only) success case. */
2307 png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
2308 (png_charp)buffer+1, (png_charp)buffer+heighti);
2311 #endif
2313 #ifdef PNG_READ_tIME_SUPPORTED
2314 void /* PRIVATE */
2315 png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2317 png_byte buf[7];
2318 png_time mod_time;
2320 png_debug(1, "in png_handle_tIME");
2322 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2323 png_chunk_error(png_ptr, "missing IHDR");
2325 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
2327 png_crc_finish(png_ptr, length);
2328 png_chunk_benign_error(png_ptr, "duplicate");
2329 return;
2332 if (png_ptr->mode & PNG_HAVE_IDAT)
2333 png_ptr->mode |= PNG_AFTER_IDAT;
2335 if (length != 7)
2337 png_crc_finish(png_ptr, length);
2338 png_chunk_benign_error(png_ptr, "invalid");
2339 return;
2342 png_crc_read(png_ptr, buf, 7);
2344 if (png_crc_finish(png_ptr, 0))
2345 return;
2347 mod_time.second = buf[6];
2348 mod_time.minute = buf[5];
2349 mod_time.hour = buf[4];
2350 mod_time.day = buf[3];
2351 mod_time.month = buf[2];
2352 mod_time.year = png_get_uint_16(buf);
2354 png_set_tIME(png_ptr, info_ptr, &mod_time);
2356 #endif
2358 #ifdef PNG_READ_tEXt_SUPPORTED
2359 /* Note: this does not properly handle chunks that are > 64K under DOS */
2360 void /* PRIVATE */
2361 png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2363 png_text text_info;
2364 png_bytep buffer;
2365 png_charp key;
2366 png_charp text;
2367 png_uint_32 skip = 0;
2369 png_debug(1, "in png_handle_tEXt");
2371 #ifdef PNG_USER_LIMITS_SUPPORTED
2372 if (png_ptr->user_chunk_cache_max != 0)
2374 if (png_ptr->user_chunk_cache_max == 1)
2376 png_crc_finish(png_ptr, length);
2377 return;
2380 if (--png_ptr->user_chunk_cache_max == 1)
2382 png_crc_finish(png_ptr, length);
2383 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2384 return;
2387 #endif
2389 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2390 png_chunk_error(png_ptr, "missing IHDR");
2392 if (png_ptr->mode & PNG_HAVE_IDAT)
2393 png_ptr->mode |= PNG_AFTER_IDAT;
2395 #ifdef PNG_MAX_MALLOC_64K
2396 if (length > 65535U)
2398 png_crc_finish(png_ptr, length);
2399 png_chunk_benign_error(png_ptr, "too large to fit in memory");
2400 return;
2402 #endif
2404 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2406 if (buffer == NULL)
2408 png_chunk_benign_error(png_ptr, "out of memory");
2409 return;
2412 png_crc_read(png_ptr, buffer, length);
2414 if (png_crc_finish(png_ptr, skip))
2415 return;
2417 key = (png_charp)buffer;
2418 key[length] = 0;
2420 for (text = key; *text; text++)
2421 /* Empty loop to find end of key */ ;
2423 if (text != key + length)
2424 text++;
2426 text_info.compression = PNG_TEXT_COMPRESSION_NONE;
2427 text_info.key = key;
2428 text_info.lang = NULL;
2429 text_info.lang_key = NULL;
2430 text_info.itxt_length = 0;
2431 text_info.text = text;
2432 text_info.text_length = strlen(text);
2434 if (png_set_text_2(png_ptr, info_ptr, &text_info, 1))
2435 png_warning(png_ptr, "Insufficient memory to process text chunk");
2437 #endif
2439 #ifdef PNG_READ_zTXt_SUPPORTED
2440 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2441 void /* PRIVATE */
2442 png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2444 png_const_charp errmsg = NULL;
2445 png_bytep buffer;
2446 png_uint_32 keyword_length;
2448 png_debug(1, "in png_handle_zTXt");
2450 #ifdef PNG_USER_LIMITS_SUPPORTED
2451 if (png_ptr->user_chunk_cache_max != 0)
2453 if (png_ptr->user_chunk_cache_max == 1)
2455 png_crc_finish(png_ptr, length);
2456 return;
2459 if (--png_ptr->user_chunk_cache_max == 1)
2461 png_crc_finish(png_ptr, length);
2462 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2463 return;
2466 #endif
2468 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2469 png_chunk_error(png_ptr, "missing IHDR");
2471 if (png_ptr->mode & PNG_HAVE_IDAT)
2472 png_ptr->mode |= PNG_AFTER_IDAT;
2474 buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
2476 if (buffer == NULL)
2478 png_crc_finish(png_ptr, length);
2479 png_chunk_benign_error(png_ptr, "out of memory");
2480 return;
2483 png_crc_read(png_ptr, buffer, length);
2485 if (png_crc_finish(png_ptr, 0))
2486 return;
2488 /* TODO: also check that the keyword contents match the spec! */
2489 for (keyword_length = 0;
2490 keyword_length < length && buffer[keyword_length] != 0;
2491 ++keyword_length)
2492 /* Empty loop to find end of name */ ;
2494 if (keyword_length > 79 || keyword_length < 1)
2495 errmsg = "bad keyword";
2497 /* zTXt must have some LZ data after the keyword, although it may expand to
2498 * zero bytes; we need a '\0' at the end of the keyword, the compression type
2499 * then the LZ data:
2501 else if (keyword_length + 3 > length)
2502 errmsg = "truncated";
2504 else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
2505 errmsg = "unknown compression type";
2507 else
2509 png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
2511 /* TODO: at present png_decompress_chunk imposes a single application
2512 * level memory limit, this should be split to different values for iCCP
2513 * and text chunks.
2515 if (png_decompress_chunk(png_ptr, length, keyword_length+2,
2516 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2518 png_text text;
2520 /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
2521 * for the extra compression type byte and the fact that it isn't
2522 * necessarily '\0' terminated.
2524 buffer = png_ptr->read_buffer;
2525 buffer[uncompressed_length+(keyword_length+2)] = 0;
2527 text.compression = PNG_TEXT_COMPRESSION_zTXt;
2528 text.key = (png_charp)buffer;
2529 text.text = (png_charp)(buffer + keyword_length+2);
2530 text.text_length = uncompressed_length;
2531 text.itxt_length = 0;
2532 text.lang = NULL;
2533 text.lang_key = NULL;
2535 if (png_set_text_2(png_ptr, info_ptr, &text, 1))
2536 errmsg = "insufficient memory";
2539 else
2540 errmsg = png_ptr->zstream.msg;
2543 if (errmsg != NULL)
2544 png_chunk_benign_error(png_ptr, errmsg);
2546 #endif
2548 #ifdef PNG_READ_iTXt_SUPPORTED
2549 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2550 void /* PRIVATE */
2551 png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2553 png_const_charp errmsg = NULL;
2554 png_bytep buffer;
2555 png_uint_32 prefix_length;
2557 png_debug(1, "in png_handle_iTXt");
2559 #ifdef PNG_USER_LIMITS_SUPPORTED
2560 if (png_ptr->user_chunk_cache_max != 0)
2562 if (png_ptr->user_chunk_cache_max == 1)
2564 png_crc_finish(png_ptr, length);
2565 return;
2568 if (--png_ptr->user_chunk_cache_max == 1)
2570 png_crc_finish(png_ptr, length);
2571 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2572 return;
2575 #endif
2577 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2578 png_chunk_error(png_ptr, "missing IHDR");
2580 if (png_ptr->mode & PNG_HAVE_IDAT)
2581 png_ptr->mode |= PNG_AFTER_IDAT;
2583 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2585 if (buffer == NULL)
2587 png_crc_finish(png_ptr, length);
2588 png_chunk_benign_error(png_ptr, "out of memory");
2589 return;
2592 png_crc_read(png_ptr, buffer, length);
2594 if (png_crc_finish(png_ptr, 0))
2595 return;
2597 /* First the keyword. */
2598 for (prefix_length=0;
2599 prefix_length < length && buffer[prefix_length] != 0;
2600 ++prefix_length)
2601 /* Empty loop */ ;
2603 /* Perform a basic check on the keyword length here. */
2604 if (prefix_length > 79 || prefix_length < 1)
2605 errmsg = "bad keyword";
2607 /* Expect keyword, compression flag, compression type, language, translated
2608 * keyword (both may be empty but are 0 terminated) then the text, which may
2609 * be empty.
2611 else if (prefix_length + 5 > length)
2612 errmsg = "truncated";
2614 else if (buffer[prefix_length+1] == 0 ||
2615 (buffer[prefix_length+1] == 1 &&
2616 buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
2618 int compressed = buffer[prefix_length+1] != 0;
2619 png_uint_32 language_offset, translated_keyword_offset;
2620 png_alloc_size_t uncompressed_length = 0;
2622 /* Now the language tag */
2623 prefix_length += 3;
2624 language_offset = prefix_length;
2626 for (; prefix_length < length && buffer[prefix_length] != 0;
2627 ++prefix_length)
2628 /* Empty loop */ ;
2630 /* WARNING: the length may be invalid here, this is checked below. */
2631 translated_keyword_offset = ++prefix_length;
2633 for (; prefix_length < length && buffer[prefix_length] != 0;
2634 ++prefix_length)
2635 /* Empty loop */ ;
2637 /* prefix_length should now be at the trailing '\0' of the translated
2638 * keyword, but it may already be over the end. None of this arithmetic
2639 * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
2640 * systems the available allocaton may overflow.
2642 ++prefix_length;
2644 if (!compressed && prefix_length <= length)
2645 uncompressed_length = length - prefix_length;
2647 else if (compressed && prefix_length < length)
2649 uncompressed_length = PNG_SIZE_MAX;
2651 /* TODO: at present png_decompress_chunk imposes a single application
2652 * level memory limit, this should be split to different values for
2653 * iCCP and text chunks.
2655 if (png_decompress_chunk(png_ptr, length, prefix_length,
2656 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2657 buffer = png_ptr->read_buffer;
2659 else
2660 errmsg = png_ptr->zstream.msg;
2663 else
2664 errmsg = "truncated";
2666 if (errmsg == NULL)
2668 png_text text;
2670 buffer[uncompressed_length+prefix_length] = 0;
2672 if (compressed)
2673 text.compression = PNG_ITXT_COMPRESSION_NONE;
2675 else
2676 text.compression = PNG_ITXT_COMPRESSION_zTXt;
2678 text.key = (png_charp)buffer;
2679 text.lang = (png_charp)buffer + language_offset;
2680 text.lang_key = (png_charp)buffer + translated_keyword_offset;
2681 text.text = (png_charp)buffer + prefix_length;
2682 text.text_length = 0;
2683 text.itxt_length = uncompressed_length;
2685 if (png_set_text_2(png_ptr, info_ptr, &text, 1))
2686 errmsg = "insufficient memory";
2690 else
2691 errmsg = "bad compression info";
2693 if (errmsg != NULL)
2694 png_chunk_benign_error(png_ptr, errmsg);
2696 #endif
2698 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2699 /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
2700 static int
2701 png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
2703 png_alloc_size_t limit = PNG_SIZE_MAX;
2705 if (png_ptr->unknown_chunk.data != NULL)
2707 png_free(png_ptr, png_ptr->unknown_chunk.data);
2708 png_ptr->unknown_chunk.data = NULL;
2711 # ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
2712 if (png_ptr->user_chunk_malloc_max > 0 &&
2713 png_ptr->user_chunk_malloc_max < limit)
2714 limit = png_ptr->user_chunk_malloc_max;
2716 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
2717 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
2718 limit = PNG_USER_CHUNK_MALLOC_MAX;
2719 # endif
2721 if (length <= limit)
2723 PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
2724 /* The following is safe because of the PNG_SIZE_MAX init above */
2725 png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
2726 /* 'mode' is a flag array, only the bottom four bits matter here */
2727 png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
2729 if (length == 0)
2730 png_ptr->unknown_chunk.data = NULL;
2732 else
2734 /* Do a 'warn' here - it is handled below. */
2735 png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
2736 png_malloc_warn(png_ptr, length));
2740 if (png_ptr->unknown_chunk.data == NULL && length > 0)
2742 /* This is benign because we clean up correctly */
2743 png_crc_finish(png_ptr, length);
2744 png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
2745 return 0;
2748 else
2750 if (length > 0)
2751 png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
2752 png_crc_finish(png_ptr, 0);
2753 return 1;
2756 #endif /* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2758 /* Handle an unknown, or known but disabled, chunk */
2759 void /* PRIVATE */
2760 png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
2761 png_uint_32 length, int keep)
2763 int handled = 0; /* the chunk was handled */
2765 png_debug(1, "in png_handle_unknown");
2767 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2768 /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
2769 * the bug which meant that setting a non-default behavior for a specific
2770 * chunk would be ignored (the default was always used unless a user
2771 * callback was installed).
2773 * 'keep' is the value from the png_chunk_unknown_handling, the setting for
2774 * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
2775 * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
2776 * This is just an optimization to avoid multiple calls to the lookup
2777 * function.
2779 # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
2780 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2781 keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
2782 # endif
2783 # endif
2785 /* One of the following methods will read the chunk or skip it (at least one
2786 * of these is always defined because this is the only way to switch on
2787 * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
2789 # ifdef PNG_READ_USER_CHUNKS_SUPPORTED
2790 /* The user callback takes precedence over the chunk keep value, but the
2791 * keep value is still required to validate a save of a critical chunk.
2793 if (png_ptr->read_user_chunk_fn != NULL)
2795 if (png_cache_unknown_chunk(png_ptr, length))
2797 /* Callback to user unknown chunk handler */
2798 int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
2799 &png_ptr->unknown_chunk);
2801 /* ret is:
2802 * negative: An error occured, png_chunk_error will be called.
2803 * zero: The chunk was not handled, the chunk will be discarded
2804 * unless png_set_keep_unknown_chunks has been used to set
2805 * a 'keep' behavior for this particular chunk, in which
2806 * case that will be used. A critical chunk will cause an
2807 * error at this point unless it is to be saved.
2808 * positive: The chunk was handled, libpng will ignore/discard it.
2810 if (ret < 0)
2811 png_chunk_error(png_ptr, "error in user chunk");
2813 else if (ret == 0)
2815 /* If the keep value is 'default' or 'never' override it, but
2816 * still error out on critical chunks unless the keep value is
2817 * 'always' While this is weird it is the behavior in 1.4.12.
2818 * A possible improvement would be to obey the value set for the
2819 * chunk, but this would be an API change that would probably
2820 * damage some applications.
2822 * The png_app_warning below catches the case that matters, where
2823 * the application has not set specific save or ignore for this
2824 * chunk or global save or ignore.
2826 if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
2828 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2829 if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
2831 png_chunk_warning(png_ptr, "Saving unknown chunk:");
2832 png_app_warning(png_ptr,
2833 "forcing save of an unhandled chunk;"
2834 " please call png_set_keep_unknown_chunks");
2835 /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
2837 # endif
2838 keep = PNG_HANDLE_CHUNK_IF_SAFE;
2842 else /* chunk was handled */
2844 handled = 1;
2845 /* Critical chunks can be safely discarded at this point. */
2846 keep = PNG_HANDLE_CHUNK_NEVER;
2850 else
2851 keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
2854 else
2855 /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
2856 # endif /* PNG_READ_USER_CHUNKS_SUPPORTED */
2858 # ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
2860 /* keep is currently just the per-chunk setting, if there was no
2861 * setting change it to the global default now (not that this may
2862 * still be AS_DEFAULT) then obtain the cache of the chunk if required,
2863 * if not simply skip the chunk.
2865 if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
2866 keep = png_ptr->unknown_default;
2868 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
2869 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
2870 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
2872 if (!png_cache_unknown_chunk(png_ptr, length))
2873 keep = PNG_HANDLE_CHUNK_NEVER;
2876 else
2877 png_crc_finish(png_ptr, length);
2879 # else
2880 # ifndef PNG_READ_USER_CHUNKS_SUPPORTED
2881 # error no method to support READ_UNKNOWN_CHUNKS
2882 # endif
2885 /* If here there is no read callback pointer set and no support is
2886 * compiled in to just save the unknown chunks, so simply skip this
2887 * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then
2888 * the app has erroneously asked for unknown chunk saving when there
2889 * is no support.
2891 if (keep > PNG_HANDLE_CHUNK_NEVER)
2892 png_app_error(png_ptr, "no unknown chunk support available");
2894 png_crc_finish(png_ptr, length);
2896 # endif
2898 # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2899 /* Now store the chunk in the chunk list if appropriate, and if the limits
2900 * permit it.
2902 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
2903 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
2904 PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
2906 # ifdef PNG_USER_LIMITS_SUPPORTED
2907 switch (png_ptr->user_chunk_cache_max)
2909 case 2:
2910 png_ptr->user_chunk_cache_max = 1;
2911 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2912 /* FALL THROUGH */
2913 case 1:
2914 /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
2915 * chunk being skipped, now there will be a hard error below.
2917 break;
2919 default: /* not at limit */
2920 --(png_ptr->user_chunk_cache_max);
2921 /* FALL THROUGH */
2922 case 0: /* no limit */
2923 # endif /* PNG_USER_LIMITS_SUPPORTED */
2924 /* Here when the limit isn't reached or when limits are compiled
2925 * out; store the chunk.
2927 png_set_unknown_chunks(png_ptr, info_ptr,
2928 &png_ptr->unknown_chunk, 1);
2929 handled = 1;
2930 # ifdef PNG_USER_LIMITS_SUPPORTED
2931 break;
2933 # endif
2935 # else /* no store support! */
2936 PNG_UNUSED(info_ptr)
2937 # error untested code (reading unknown chunks with no store support)
2938 # endif
2940 /* Regardless of the error handling below the cached data (if any) can be
2941 * freed now. Notice that the data is not freed if there is a png_error, but
2942 * it will be freed by destroy_read_struct.
2944 if (png_ptr->unknown_chunk.data != NULL)
2945 png_free(png_ptr, png_ptr->unknown_chunk.data);
2946 png_ptr->unknown_chunk.data = NULL;
2948 #else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2949 /* There is no support to read an unknown chunk, so just skip it. */
2950 png_crc_finish(png_ptr, length);
2951 PNG_UNUSED(info_ptr)
2952 PNG_UNUSED(keep)
2953 #endif /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2955 /* Check for unhandled critical chunks */
2956 if (!handled && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
2957 png_chunk_error(png_ptr, "unhandled critical chunk");
2960 /* This function is called to verify that a chunk name is valid.
2961 * This function can't have the "critical chunk check" incorporated
2962 * into it, since in the future we will need to be able to call user
2963 * functions to handle unknown critical chunks after we check that
2964 * the chunk name itself is valid.
2967 /* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
2969 * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
2972 void /* PRIVATE */
2973 png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
2975 int i;
2977 png_debug(1, "in png_check_chunk_name");
2979 for (i=1; i<=4; ++i)
2981 int c = chunk_name & 0xff;
2983 if (c < 65 || c > 122 || (c > 90 && c < 97))
2984 png_chunk_error(png_ptr, "invalid chunk type");
2986 chunk_name >>= 8;
2990 /* Combines the row recently read in with the existing pixels in the row. This
2991 * routine takes care of alpha and transparency if requested. This routine also
2992 * handles the two methods of progressive display of interlaced images,
2993 * depending on the 'display' value; if 'display' is true then the whole row
2994 * (dp) is filled from the start by replicating the available pixels. If
2995 * 'display' is false only those pixels present in the pass are filled in.
2997 void /* PRIVATE */
2998 png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
3000 unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
3001 png_const_bytep sp = png_ptr->row_buf + 1;
3002 png_uint_32 row_width = png_ptr->width;
3003 unsigned int pass = png_ptr->pass;
3004 png_bytep end_ptr = 0;
3005 png_byte end_byte = 0;
3006 unsigned int end_mask;
3008 png_debug(1, "in png_combine_row");
3010 /* Added in 1.5.6: it should not be possible to enter this routine until at
3011 * least one row has been read from the PNG data and transformed.
3013 if (pixel_depth == 0)
3014 png_error(png_ptr, "internal row logic error");
3016 /* Added in 1.5.4: the pixel depth should match the information returned by
3017 * any call to png_read_update_info at this point. Do not continue if we got
3018 * this wrong.
3020 if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
3021 PNG_ROWBYTES(pixel_depth, row_width))
3022 png_error(png_ptr, "internal row size calculation error");
3024 /* Don't expect this to ever happen: */
3025 if (row_width == 0)
3026 png_error(png_ptr, "internal row width error");
3028 /* Preserve the last byte in cases where only part of it will be overwritten,
3029 * the multiply below may overflow, we don't care because ANSI-C guarantees
3030 * we get the low bits.
3032 end_mask = (pixel_depth * row_width) & 7;
3033 if (end_mask != 0)
3035 /* end_ptr == NULL is a flag to say do nothing */
3036 end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
3037 end_byte = *end_ptr;
3038 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3039 if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
3040 end_mask = 0xff << end_mask;
3042 else /* big-endian byte */
3043 # endif
3044 end_mask = 0xff >> end_mask;
3045 /* end_mask is now the bits to *keep* from the destination row */
3048 /* For non-interlaced images this reduces to a memcpy(). A memcpy()
3049 * will also happen if interlacing isn't supported or if the application
3050 * does not call png_set_interlace_handling(). In the latter cases the
3051 * caller just gets a sequence of the unexpanded rows from each interlace
3052 * pass.
3054 #ifdef PNG_READ_INTERLACING_SUPPORTED
3055 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
3056 pass < 6 && (display == 0 ||
3057 /* The following copies everything for 'display' on passes 0, 2 and 4. */
3058 (display == 1 && (pass & 1) != 0)))
3060 /* Narrow images may have no bits in a pass; the caller should handle
3061 * this, but this test is cheap:
3063 if (row_width <= PNG_PASS_START_COL(pass))
3064 return;
3066 if (pixel_depth < 8)
3068 /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
3069 * into 32 bits, then a single loop over the bytes using the four byte
3070 * values in the 32-bit mask can be used. For the 'display' option the
3071 * expanded mask may also not require any masking within a byte. To
3072 * make this work the PACKSWAP option must be taken into account - it
3073 * simply requires the pixels to be reversed in each byte.
3075 * The 'regular' case requires a mask for each of the first 6 passes,
3076 * the 'display' case does a copy for the even passes in the range
3077 * 0..6. This has already been handled in the test above.
3079 * The masks are arranged as four bytes with the first byte to use in
3080 * the lowest bits (little-endian) regardless of the order (PACKSWAP or
3081 * not) of the pixels in each byte.
3083 * NOTE: the whole of this logic depends on the caller of this function
3084 * only calling it on rows appropriate to the pass. This function only
3085 * understands the 'x' logic; the 'y' logic is handled by the caller.
3087 * The following defines allow generation of compile time constant bit
3088 * masks for each pixel depth and each possibility of swapped or not
3089 * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index,
3090 * is in the range 0..7; and the result is 1 if the pixel is to be
3091 * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B'
3092 * for the block method.
3094 * With some compilers a compile time expression of the general form:
3096 * (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
3098 * Produces warnings with values of 'shift' in the range 33 to 63
3099 * because the right hand side of the ?: expression is evaluated by
3100 * the compiler even though it isn't used. Microsoft Visual C (various
3101 * versions) and the Intel C compiler are known to do this. To avoid
3102 * this the following macros are used in 1.5.6. This is a temporary
3103 * solution to avoid destabilizing the code during the release process.
3105 # if PNG_USE_COMPILE_TIME_MASKS
3106 # define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
3107 # define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
3108 # else
3109 # define PNG_LSR(x,s) ((x)>>(s))
3110 # define PNG_LSL(x,s) ((x)<<(s))
3111 # endif
3112 # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
3113 PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
3114 # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
3115 PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
3117 /* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is
3118 * little endian - the first pixel is at bit 0 - however the extra
3119 * parameter 's' can be set to cause the mask position to be swapped
3120 * within each byte, to match the PNG format. This is done by XOR of
3121 * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
3123 # define PIXEL_MASK(p,x,d,s) \
3124 (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
3126 /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
3128 # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3129 # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3131 /* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp
3132 * cases the result needs replicating, for the 4-bpp case the above
3133 * generates a full 32 bits.
3135 # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
3137 # define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
3138 S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
3139 S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
3141 # define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
3142 B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
3143 B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
3145 #if PNG_USE_COMPILE_TIME_MASKS
3146 /* Utility macros to construct all the masks for a depth/swap
3147 * combination. The 's' parameter says whether the format is PNG
3148 * (big endian bytes) or not. Only the three odd-numbered passes are
3149 * required for the display/block algorithm.
3151 # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
3152 S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
3154 # define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }
3156 # define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
3158 /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
3159 * then pass:
3161 static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
3163 /* Little-endian byte masks for PACKSWAP */
3164 { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
3165 /* Normal (big-endian byte) masks - PNG format */
3166 { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
3169 /* display_mask has only three entries for the odd passes, so index by
3170 * pass>>1.
3172 static PNG_CONST png_uint_32 display_mask[2][3][3] =
3174 /* Little-endian byte masks for PACKSWAP */
3175 { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
3176 /* Normal (big-endian byte) masks - PNG format */
3177 { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
3180 # define MASK(pass,depth,display,png)\
3181 ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
3182 row_mask[png][DEPTH_INDEX(depth)][pass])
3184 #else /* !PNG_USE_COMPILE_TIME_MASKS */
3185 /* This is the runtime alternative: it seems unlikely that this will
3186 * ever be either smaller or faster than the compile time approach.
3188 # define MASK(pass,depth,display,png)\
3189 ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
3190 #endif /* !PNG_USE_COMPILE_TIME_MASKS */
3192 /* Use the appropriate mask to copy the required bits. In some cases
3193 * the byte mask will be 0 or 0xff, optimize these cases. row_width is
3194 * the number of pixels, but the code copies bytes, so it is necessary
3195 * to special case the end.
3197 png_uint_32 pixels_per_byte = 8 / pixel_depth;
3198 png_uint_32 mask;
3200 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3201 if (png_ptr->transformations & PNG_PACKSWAP)
3202 mask = MASK(pass, pixel_depth, display, 0);
3204 else
3205 # endif
3206 mask = MASK(pass, pixel_depth, display, 1);
3208 for (;;)
3210 png_uint_32 m;
3212 /* It doesn't matter in the following if png_uint_32 has more than
3213 * 32 bits because the high bits always match those in m<<24; it is,
3214 * however, essential to use OR here, not +, because of this.
3216 m = mask;
3217 mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
3218 m &= 0xff;
3220 if (m != 0) /* something to copy */
3222 if (m != 0xff)
3223 *dp = (png_byte)((*dp & ~m) | (*sp & m));
3224 else
3225 *dp = *sp;
3228 /* NOTE: this may overwrite the last byte with garbage if the image
3229 * is not an exact number of bytes wide; libpng has always done
3230 * this.
3232 if (row_width <= pixels_per_byte)
3233 break; /* May need to restore part of the last byte */
3235 row_width -= pixels_per_byte;
3236 ++dp;
3237 ++sp;
3241 else /* pixel_depth >= 8 */
3243 unsigned int bytes_to_copy, bytes_to_jump;
3245 /* Validate the depth - it must be a multiple of 8 */
3246 if (pixel_depth & 7)
3247 png_error(png_ptr, "invalid user transform pixel depth");
3249 pixel_depth >>= 3; /* now in bytes */
3250 row_width *= pixel_depth;
3252 /* Regardless of pass number the Adam 7 interlace always results in a
3253 * fixed number of pixels to copy then to skip. There may be a
3254 * different number of pixels to skip at the start though.
3257 unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
3259 row_width -= offset;
3260 dp += offset;
3261 sp += offset;
3264 /* Work out the bytes to copy. */
3265 if (display)
3267 /* When doing the 'block' algorithm the pixel in the pass gets
3268 * replicated to adjacent pixels. This is why the even (0,2,4,6)
3269 * passes are skipped above - the entire expanded row is copied.
3271 bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
3273 /* But don't allow this number to exceed the actual row width. */
3274 if (bytes_to_copy > row_width)
3275 bytes_to_copy = row_width;
3278 else /* normal row; Adam7 only ever gives us one pixel to copy. */
3279 bytes_to_copy = pixel_depth;
3281 /* In Adam7 there is a constant offset between where the pixels go. */
3282 bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
3284 /* And simply copy these bytes. Some optimization is possible here,
3285 * depending on the value of 'bytes_to_copy'. Special case the low
3286 * byte counts, which we know to be frequent.
3288 * Notice that these cases all 'return' rather than 'break' - this
3289 * avoids an unnecessary test on whether to restore the last byte
3290 * below.
3292 switch (bytes_to_copy)
3294 case 1:
3295 for (;;)
3297 *dp = *sp;
3299 if (row_width <= bytes_to_jump)
3300 return;
3302 dp += bytes_to_jump;
3303 sp += bytes_to_jump;
3304 row_width -= bytes_to_jump;
3307 case 2:
3308 /* There is a possibility of a partial copy at the end here; this
3309 * slows the code down somewhat.
3313 dp[0] = sp[0], dp[1] = sp[1];
3315 if (row_width <= bytes_to_jump)
3316 return;
3318 sp += bytes_to_jump;
3319 dp += bytes_to_jump;
3320 row_width -= bytes_to_jump;
3322 while (row_width > 1);
3324 /* And there can only be one byte left at this point: */
3325 *dp = *sp;
3326 return;
3328 case 3:
3329 /* This can only be the RGB case, so each copy is exactly one
3330 * pixel and it is not necessary to check for a partial copy.
3332 for(;;)
3334 dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
3336 if (row_width <= bytes_to_jump)
3337 return;
3339 sp += bytes_to_jump;
3340 dp += bytes_to_jump;
3341 row_width -= bytes_to_jump;
3344 default:
3345 #if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
3346 /* Check for double byte alignment and, if possible, use a
3347 * 16-bit copy. Don't attempt this for narrow images - ones that
3348 * are less than an interlace panel wide. Don't attempt it for
3349 * wide bytes_to_copy either - use the memcpy there.
3351 if (bytes_to_copy < 16 /*else use memcpy*/ &&
3352 png_isaligned(dp, png_uint_16) &&
3353 png_isaligned(sp, png_uint_16) &&
3354 bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
3355 bytes_to_jump % (sizeof (png_uint_16)) == 0)
3357 /* Everything is aligned for png_uint_16 copies, but try for
3358 * png_uint_32 first.
3360 if (png_isaligned(dp, png_uint_32) &&
3361 png_isaligned(sp, png_uint_32) &&
3362 bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
3363 bytes_to_jump % (sizeof (png_uint_32)) == 0)
3365 png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
3366 png_const_uint_32p sp32 = png_aligncastconst(
3367 png_const_uint_32p, sp);
3368 size_t skip = (bytes_to_jump-bytes_to_copy) /
3369 (sizeof (png_uint_32));
3373 size_t c = bytes_to_copy;
3376 *dp32++ = *sp32++;
3377 c -= (sizeof (png_uint_32));
3379 while (c > 0);
3381 if (row_width <= bytes_to_jump)
3382 return;
3384 dp32 += skip;
3385 sp32 += skip;
3386 row_width -= bytes_to_jump;
3388 while (bytes_to_copy <= row_width);
3390 /* Get to here when the row_width truncates the final copy.
3391 * There will be 1-3 bytes left to copy, so don't try the
3392 * 16-bit loop below.
3394 dp = (png_bytep)dp32;
3395 sp = (png_const_bytep)sp32;
3397 *dp++ = *sp++;
3398 while (--row_width > 0);
3399 return;
3402 /* Else do it in 16-bit quantities, but only if the size is
3403 * not too large.
3405 else
3407 png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
3408 png_const_uint_16p sp16 = png_aligncastconst(
3409 png_const_uint_16p, sp);
3410 size_t skip = (bytes_to_jump-bytes_to_copy) /
3411 (sizeof (png_uint_16));
3415 size_t c = bytes_to_copy;
3418 *dp16++ = *sp16++;
3419 c -= (sizeof (png_uint_16));
3421 while (c > 0);
3423 if (row_width <= bytes_to_jump)
3424 return;
3426 dp16 += skip;
3427 sp16 += skip;
3428 row_width -= bytes_to_jump;
3430 while (bytes_to_copy <= row_width);
3432 /* End of row - 1 byte left, bytes_to_copy > row_width: */
3433 dp = (png_bytep)dp16;
3434 sp = (png_const_bytep)sp16;
3436 *dp++ = *sp++;
3437 while (--row_width > 0);
3438 return;
3441 #endif /* PNG_ALIGN_ code */
3443 /* The true default - use a memcpy: */
3444 for (;;)
3446 memcpy(dp, sp, bytes_to_copy);
3448 if (row_width <= bytes_to_jump)
3449 return;
3451 sp += bytes_to_jump;
3452 dp += bytes_to_jump;
3453 row_width -= bytes_to_jump;
3454 if (bytes_to_copy > row_width)
3455 bytes_to_copy = row_width;
3459 /* NOT REACHED*/
3460 } /* pixel_depth >= 8 */
3462 /* Here if pixel_depth < 8 to check 'end_ptr' below. */
3464 else
3465 #endif
3467 /* If here then the switch above wasn't used so just memcpy the whole row
3468 * from the temporary row buffer (notice that this overwrites the end of the
3469 * destination row if it is a partial byte.)
3471 memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
3473 /* Restore the overwritten bits from the last byte if necessary. */
3474 if (end_ptr != NULL)
3475 *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
3478 #ifdef PNG_READ_INTERLACING_SUPPORTED
3479 void /* PRIVATE */
3480 png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
3481 png_uint_32 transformations /* Because these may affect the byte layout */)
3483 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
3484 /* Offset to next interlace block */
3485 static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
3487 png_debug(1, "in png_do_read_interlace");
3488 if (row != NULL && row_info != NULL)
3490 png_uint_32 final_width;
3492 final_width = row_info->width * png_pass_inc[pass];
3494 switch (row_info->pixel_depth)
3496 case 1:
3498 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
3499 png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
3500 int sshift, dshift;
3501 int s_start, s_end, s_inc;
3502 int jstop = png_pass_inc[pass];
3503 png_byte v;
3504 png_uint_32 i;
3505 int j;
3507 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3508 if (transformations & PNG_PACKSWAP)
3510 sshift = (int)((row_info->width + 7) & 0x07);
3511 dshift = (int)((final_width + 7) & 0x07);
3512 s_start = 7;
3513 s_end = 0;
3514 s_inc = -1;
3517 else
3518 #endif
3520 sshift = 7 - (int)((row_info->width + 7) & 0x07);
3521 dshift = 7 - (int)((final_width + 7) & 0x07);
3522 s_start = 0;
3523 s_end = 7;
3524 s_inc = 1;
3527 for (i = 0; i < row_info->width; i++)
3529 v = (png_byte)((*sp >> sshift) & 0x01);
3530 for (j = 0; j < jstop; j++)
3532 unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
3533 tmp |= v << dshift;
3534 *dp = (png_byte)(tmp & 0xff);
3536 if (dshift == s_end)
3538 dshift = s_start;
3539 dp--;
3542 else
3543 dshift += s_inc;
3546 if (sshift == s_end)
3548 sshift = s_start;
3549 sp--;
3552 else
3553 sshift += s_inc;
3555 break;
3558 case 2:
3560 png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
3561 png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
3562 int sshift, dshift;
3563 int s_start, s_end, s_inc;
3564 int jstop = png_pass_inc[pass];
3565 png_uint_32 i;
3567 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3568 if (transformations & PNG_PACKSWAP)
3570 sshift = (int)(((row_info->width + 3) & 0x03) << 1);
3571 dshift = (int)(((final_width + 3) & 0x03) << 1);
3572 s_start = 6;
3573 s_end = 0;
3574 s_inc = -2;
3577 else
3578 #endif
3580 sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
3581 dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
3582 s_start = 0;
3583 s_end = 6;
3584 s_inc = 2;
3587 for (i = 0; i < row_info->width; i++)
3589 png_byte v;
3590 int j;
3592 v = (png_byte)((*sp >> sshift) & 0x03);
3593 for (j = 0; j < jstop; j++)
3595 unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
3596 tmp |= v << dshift;
3597 *dp = (png_byte)(tmp & 0xff);
3599 if (dshift == s_end)
3601 dshift = s_start;
3602 dp--;
3605 else
3606 dshift += s_inc;
3609 if (sshift == s_end)
3611 sshift = s_start;
3612 sp--;
3615 else
3616 sshift += s_inc;
3618 break;
3621 case 4:
3623 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
3624 png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
3625 int sshift, dshift;
3626 int s_start, s_end, s_inc;
3627 png_uint_32 i;
3628 int jstop = png_pass_inc[pass];
3630 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3631 if (transformations & PNG_PACKSWAP)
3633 sshift = (int)(((row_info->width + 1) & 0x01) << 2);
3634 dshift = (int)(((final_width + 1) & 0x01) << 2);
3635 s_start = 4;
3636 s_end = 0;
3637 s_inc = -4;
3640 else
3641 #endif
3643 sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
3644 dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
3645 s_start = 0;
3646 s_end = 4;
3647 s_inc = 4;
3650 for (i = 0; i < row_info->width; i++)
3652 png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
3653 int j;
3655 for (j = 0; j < jstop; j++)
3657 unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
3658 tmp |= v << dshift;
3659 *dp = (png_byte)(tmp & 0xff);
3661 if (dshift == s_end)
3663 dshift = s_start;
3664 dp--;
3667 else
3668 dshift += s_inc;
3671 if (sshift == s_end)
3673 sshift = s_start;
3674 sp--;
3677 else
3678 sshift += s_inc;
3680 break;
3683 default:
3685 png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
3687 png_bytep sp = row + (png_size_t)(row_info->width - 1)
3688 * pixel_bytes;
3690 png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
3692 int jstop = png_pass_inc[pass];
3693 png_uint_32 i;
3695 for (i = 0; i < row_info->width; i++)
3697 png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
3698 int j;
3700 memcpy(v, sp, pixel_bytes);
3702 for (j = 0; j < jstop; j++)
3704 memcpy(dp, v, pixel_bytes);
3705 dp -= pixel_bytes;
3708 sp -= pixel_bytes;
3710 break;
3714 row_info->width = final_width;
3715 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
3717 #ifndef PNG_READ_PACKSWAP_SUPPORTED
3718 PNG_UNUSED(transformations) /* Silence compiler warning */
3719 #endif
3721 #endif /* PNG_READ_INTERLACING_SUPPORTED */
3723 static void
3724 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
3725 png_const_bytep prev_row)
3727 png_size_t i;
3728 png_size_t istop = row_info->rowbytes;
3729 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3730 png_bytep rp = row + bpp;
3732 PNG_UNUSED(prev_row)
3734 for (i = bpp; i < istop; i++)
3736 *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
3737 rp++;
3741 static void
3742 png_read_filter_row_up(png_row_infop row_info, png_bytep row,
3743 png_const_bytep prev_row)
3745 png_size_t i;
3746 png_size_t istop = row_info->rowbytes;
3747 png_bytep rp = row;
3748 png_const_bytep pp = prev_row;
3750 for (i = 0; i < istop; i++)
3752 *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
3753 rp++;
3757 static void
3758 png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
3759 png_const_bytep prev_row)
3761 png_size_t i;
3762 png_bytep rp = row;
3763 png_const_bytep pp = prev_row;
3764 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3765 png_size_t istop = row_info->rowbytes - bpp;
3767 for (i = 0; i < bpp; i++)
3769 *rp = (png_byte)(((int)(*rp) +
3770 ((int)(*pp++) / 2 )) & 0xff);
3772 rp++;
3775 for (i = 0; i < istop; i++)
3777 *rp = (png_byte)(((int)(*rp) +
3778 (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
3780 rp++;
3784 static void
3785 png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
3786 png_const_bytep prev_row)
3788 png_bytep rp_end = row + row_info->rowbytes;
3789 int a, c;
3791 /* First pixel/byte */
3792 c = *prev_row++;
3793 a = *row + c;
3794 *row++ = (png_byte)a;
3796 /* Remainder */
3797 while (row < rp_end)
3799 int b, pa, pb, pc, p;
3801 a &= 0xff; /* From previous iteration or start */
3802 b = *prev_row++;
3804 p = b - c;
3805 pc = a - c;
3807 # ifdef PNG_USE_ABS
3808 pa = abs(p);
3809 pb = abs(pc);
3810 pc = abs(p + pc);
3811 # else
3812 pa = p < 0 ? -p : p;
3813 pb = pc < 0 ? -pc : pc;
3814 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3815 # endif
3817 /* Find the best predictor, the least of pa, pb, pc favoring the earlier
3818 * ones in the case of a tie.
3820 if (pb < pa) pa = pb, a = b;
3821 if (pc < pa) a = c;
3823 /* Calculate the current pixel in a, and move the previous row pixel to c
3824 * for the next time round the loop
3826 c = b;
3827 a += *row;
3828 *row++ = (png_byte)a;
3832 static void
3833 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
3834 png_const_bytep prev_row)
3836 int bpp = (row_info->pixel_depth + 7) >> 3;
3837 png_bytep rp_end = row + bpp;
3839 /* Process the first pixel in the row completely (this is the same as 'up'
3840 * because there is only one candidate predictor for the first row).
3842 while (row < rp_end)
3844 int a = *row + *prev_row++;
3845 *row++ = (png_byte)a;
3848 /* Remainder */
3849 rp_end += row_info->rowbytes - bpp;
3851 while (row < rp_end)
3853 int a, b, c, pa, pb, pc, p;
3855 c = *(prev_row - bpp);
3856 a = *(row - bpp);
3857 b = *prev_row++;
3859 p = b - c;
3860 pc = a - c;
3862 # ifdef PNG_USE_ABS
3863 pa = abs(p);
3864 pb = abs(pc);
3865 pc = abs(p + pc);
3866 # else
3867 pa = p < 0 ? -p : p;
3868 pb = pc < 0 ? -pc : pc;
3869 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3870 # endif
3872 if (pb < pa) pa = pb, a = b;
3873 if (pc < pa) a = c;
3875 c = b;
3876 a += *row;
3877 *row++ = (png_byte)a;
3881 static void
3882 png_init_filter_functions(png_structrp pp)
3883 /* This function is called once for every PNG image to set the
3884 * implementations required to reverse the filtering of PNG rows. Reversing
3885 * the filter is the first transformation performed on the row data. It is
3886 * performed in place, therefore an implementation can be selected based on
3887 * the image pixel format. If the implementation depends on image width then
3888 * take care to ensure that it works correctly if the image is interlaced -
3889 * interlacing causes the actual row width to vary.
3892 unsigned int bpp = (pp->pixel_depth + 7) >> 3;
3894 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
3895 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
3896 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
3897 if (bpp == 1)
3898 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
3899 png_read_filter_row_paeth_1byte_pixel;
3900 else
3901 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
3902 png_read_filter_row_paeth_multibyte_pixel;
3904 #ifdef PNG_FILTER_OPTIMIZATIONS
3905 /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
3906 * call to install hardware optimizations for the above functions; simply
3907 * replace whatever elements of the pp->read_filter[] array with a hardware
3908 * specific (or, for that matter, generic) optimization.
3910 * To see an example of this examine what configure.ac does when
3911 * --enable-arm-neon is specified on the command line.
3913 PNG_FILTER_OPTIMIZATIONS(pp, bpp);
3914 #endif
3917 void /* PRIVATE */
3918 png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
3919 png_const_bytep prev_row, int filter)
3921 /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
3922 * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
3923 * implementations. See png_init_filter_functions above.
3925 if (pp->read_filter[0] == NULL)
3926 png_init_filter_functions(pp);
3927 if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
3928 pp->read_filter[filter-1](row_info, row, prev_row);
3931 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
3932 void /* PRIVATE */
3933 png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
3934 png_alloc_size_t avail_out)
3936 /* Loop reading IDATs and decompressing the result into output[avail_out] */
3937 png_ptr->zstream.next_out = output;
3938 png_ptr->zstream.avail_out = 0; /* safety: set below */
3940 if (output == NULL)
3941 avail_out = 0;
3945 int ret;
3946 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
3948 if (png_ptr->zstream.avail_in == 0)
3950 uInt avail_in;
3951 png_bytep buffer;
3953 while (png_ptr->idat_size == 0)
3955 png_crc_finish(png_ptr, 0);
3957 png_ptr->idat_size = png_read_chunk_header(png_ptr);
3958 /* This is an error even in the 'check' case because the code just
3959 * consumed a non-IDAT header.
3961 if (png_ptr->chunk_name != png_IDAT)
3962 png_error(png_ptr, "Not enough image data");
3965 avail_in = png_ptr->IDAT_read_size;
3967 if (avail_in > png_ptr->idat_size)
3968 avail_in = (uInt)png_ptr->idat_size;
3970 /* A PNG with a gradually increasing IDAT size will defeat this attempt
3971 * to minimize memory usage by causing lots of re-allocs, but
3972 * realistically doing IDAT_read_size re-allocs is not likely to be a
3973 * big problem.
3975 buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
3977 png_crc_read(png_ptr, buffer, avail_in);
3978 png_ptr->idat_size -= avail_in;
3980 png_ptr->zstream.next_in = buffer;
3981 png_ptr->zstream.avail_in = avail_in;
3984 /* And set up the output side. */
3985 if (output != NULL) /* standard read */
3987 uInt out = ZLIB_IO_MAX;
3989 if (out > avail_out)
3990 out = (uInt)avail_out;
3992 avail_out -= out;
3993 png_ptr->zstream.avail_out = out;
3996 else /* after last row, checking for end */
3998 png_ptr->zstream.next_out = tmpbuf;
3999 png_ptr->zstream.avail_out = (sizeof tmpbuf);
4002 /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
4003 * process. If the LZ stream is truncated the sequential reader will
4004 * terminally damage the stream, above, by reading the chunk header of the
4005 * following chunk (it then exits with png_error).
4007 * TODO: deal more elegantly with truncated IDAT lists.
4009 ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
4011 /* Take the unconsumed output back. */
4012 if (output != NULL)
4013 avail_out += png_ptr->zstream.avail_out;
4015 else /* avail_out counts the extra bytes */
4016 avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
4018 png_ptr->zstream.avail_out = 0;
4020 if (ret == Z_STREAM_END)
4022 /* Do this for safety; we won't read any more into this row. */
4023 png_ptr->zstream.next_out = NULL;
4025 png_ptr->mode |= PNG_AFTER_IDAT;
4026 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4028 if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
4029 png_chunk_benign_error(png_ptr, "Extra compressed data");
4030 break;
4033 if (ret != Z_OK)
4035 png_zstream_error(png_ptr, ret);
4037 if (output != NULL)
4038 png_chunk_error(png_ptr, png_ptr->zstream.msg);
4040 else /* checking */
4042 png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
4043 return;
4046 } while (avail_out > 0);
4048 if (avail_out > 0)
4050 /* The stream ended before the image; this is the same as too few IDATs so
4051 * should be handled the same way.
4053 if (output != NULL)
4054 png_error(png_ptr, "Not enough image data");
4056 else /* the deflate stream contained extra data */
4057 png_chunk_benign_error(png_ptr, "Too much image data");
4061 void /* PRIVATE */
4062 png_read_finish_IDAT(png_structrp png_ptr)
4064 /* We don't need any more data and the stream should have ended, however the
4065 * LZ end code may actually not have been processed. In this case we must
4066 * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
4067 * may still remain to be consumed.
4069 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
4071 /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
4072 * the compressed stream, but the stream may be damaged too, so even after
4073 * this call we may need to terminate the zstream ownership.
4075 png_read_IDAT_data(png_ptr, NULL, 0);
4076 png_ptr->zstream.next_out = NULL; /* safety */
4078 /* Now clear everything out for safety; the following may not have been
4079 * done.
4081 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
4083 png_ptr->mode |= PNG_AFTER_IDAT;
4084 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4088 /* If the zstream has not been released do it now *and* terminate the reading
4089 * of the final IDAT chunk.
4091 if (png_ptr->zowner == png_IDAT)
4093 /* Always do this; the pointers otherwise point into the read buffer. */
4094 png_ptr->zstream.next_in = NULL;
4095 png_ptr->zstream.avail_in = 0;
4097 /* Now we no longer own the zstream. */
4098 png_ptr->zowner = 0;
4100 /* The slightly weird semantics of the sequential IDAT reading is that we
4101 * are always in or at the end of an IDAT chunk, so we always need to do a
4102 * crc_finish here. If idat_size is non-zero we also need to read the
4103 * spurious bytes at the end of the chunk now.
4105 (void)png_crc_finish(png_ptr, png_ptr->idat_size);
4109 void /* PRIVATE */
4110 png_read_finish_row(png_structrp png_ptr)
4112 #ifdef PNG_READ_INTERLACING_SUPPORTED
4113 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4115 /* Start of interlace block */
4116 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4118 /* Offset to next interlace block */
4119 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4121 /* Start of interlace block in the y direction */
4122 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4124 /* Offset to next interlace block in the y direction */
4125 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4126 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4128 png_debug(1, "in png_read_finish_row");
4129 png_ptr->row_number++;
4130 if (png_ptr->row_number < png_ptr->num_rows)
4131 return;
4133 #ifdef PNG_READ_INTERLACING_SUPPORTED
4134 if (png_ptr->interlaced)
4136 png_ptr->row_number = 0;
4138 /* TO DO: don't do this if prev_row isn't needed (requires
4139 * read-ahead of the next row's filter byte.
4141 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4145 png_ptr->pass++;
4147 if (png_ptr->pass >= 7)
4148 break;
4150 png_ptr->iwidth = (png_ptr->width +
4151 png_pass_inc[png_ptr->pass] - 1 -
4152 png_pass_start[png_ptr->pass]) /
4153 png_pass_inc[png_ptr->pass];
4155 if (!(png_ptr->transformations & PNG_INTERLACE))
4157 png_ptr->num_rows = (png_ptr->height +
4158 png_pass_yinc[png_ptr->pass] - 1 -
4159 png_pass_ystart[png_ptr->pass]) /
4160 png_pass_yinc[png_ptr->pass];
4163 else /* if (png_ptr->transformations & PNG_INTERLACE) */
4164 break; /* libpng deinterlacing sees every row */
4166 } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
4168 if (png_ptr->pass < 7)
4169 return;
4171 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4173 /* Here after at the end of the last row of the last pass. */
4174 png_read_finish_IDAT(png_ptr);
4176 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
4178 void /* PRIVATE */
4179 png_read_start_row(png_structrp png_ptr)
4181 #ifdef PNG_READ_INTERLACING_SUPPORTED
4182 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4184 /* Start of interlace block */
4185 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4187 /* Offset to next interlace block */
4188 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4190 /* Start of interlace block in the y direction */
4191 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4193 /* Offset to next interlace block in the y direction */
4194 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4195 #endif
4197 int max_pixel_depth;
4198 png_size_t row_bytes;
4200 png_debug(1, "in png_read_start_row");
4202 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
4203 png_init_read_transformations(png_ptr);
4204 #endif
4205 #ifdef PNG_READ_INTERLACING_SUPPORTED
4206 if (png_ptr->interlaced)
4208 if (!(png_ptr->transformations & PNG_INTERLACE))
4209 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
4210 png_pass_ystart[0]) / png_pass_yinc[0];
4212 else
4213 png_ptr->num_rows = png_ptr->height;
4215 png_ptr->iwidth = (png_ptr->width +
4216 png_pass_inc[png_ptr->pass] - 1 -
4217 png_pass_start[png_ptr->pass]) /
4218 png_pass_inc[png_ptr->pass];
4221 else
4222 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4224 png_ptr->num_rows = png_ptr->height;
4225 png_ptr->iwidth = png_ptr->width;
4228 max_pixel_depth = png_ptr->pixel_depth;
4230 /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of
4231 * calculations to calculate the final pixel depth, then
4232 * png_do_read_transforms actually does the transforms. This means that the
4233 * code which effectively calculates this value is actually repeated in three
4234 * separate places. They must all match. Innocent changes to the order of
4235 * transformations can and will break libpng in a way that causes memory
4236 * overwrites.
4238 * TODO: fix this.
4240 #ifdef PNG_READ_PACK_SUPPORTED
4241 if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
4242 max_pixel_depth = 8;
4243 #endif
4245 #ifdef PNG_READ_EXPAND_SUPPORTED
4246 if (png_ptr->transformations & PNG_EXPAND)
4248 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4250 if (png_ptr->num_trans)
4251 max_pixel_depth = 32;
4253 else
4254 max_pixel_depth = 24;
4257 else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4259 if (max_pixel_depth < 8)
4260 max_pixel_depth = 8;
4262 if (png_ptr->num_trans)
4263 max_pixel_depth *= 2;
4266 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
4268 if (png_ptr->num_trans)
4270 max_pixel_depth *= 4;
4271 max_pixel_depth /= 3;
4275 #endif
4277 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4278 if (png_ptr->transformations & PNG_EXPAND_16)
4280 # ifdef PNG_READ_EXPAND_SUPPORTED
4281 /* In fact it is an error if it isn't supported, but checking is
4282 * the safe way.
4284 if (png_ptr->transformations & PNG_EXPAND)
4286 if (png_ptr->bit_depth < 16)
4287 max_pixel_depth *= 2;
4289 else
4290 # endif
4291 png_ptr->transformations &= ~PNG_EXPAND_16;
4293 #endif
4295 #ifdef PNG_READ_FILLER_SUPPORTED
4296 if (png_ptr->transformations & (PNG_FILLER))
4298 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4300 if (max_pixel_depth <= 8)
4301 max_pixel_depth = 16;
4303 else
4304 max_pixel_depth = 32;
4307 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
4308 png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4310 if (max_pixel_depth <= 32)
4311 max_pixel_depth = 32;
4313 else
4314 max_pixel_depth = 64;
4317 #endif
4319 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4320 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
4322 if (
4323 #ifdef PNG_READ_EXPAND_SUPPORTED
4324 (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
4325 #endif
4326 #ifdef PNG_READ_FILLER_SUPPORTED
4327 (png_ptr->transformations & (PNG_FILLER)) ||
4328 #endif
4329 png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4331 if (max_pixel_depth <= 16)
4332 max_pixel_depth = 32;
4334 else
4335 max_pixel_depth = 64;
4338 else
4340 if (max_pixel_depth <= 8)
4342 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4343 max_pixel_depth = 32;
4345 else
4346 max_pixel_depth = 24;
4349 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4350 max_pixel_depth = 64;
4352 else
4353 max_pixel_depth = 48;
4356 #endif
4358 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
4359 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
4360 if (png_ptr->transformations & PNG_USER_TRANSFORM)
4362 int user_pixel_depth = png_ptr->user_transform_depth *
4363 png_ptr->user_transform_channels;
4365 if (user_pixel_depth > max_pixel_depth)
4366 max_pixel_depth = user_pixel_depth;
4368 #endif
4370 /* This value is stored in png_struct and double checked in the row read
4371 * code.
4373 png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
4374 png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
4376 /* Align the width on the next larger 8 pixels. Mainly used
4377 * for interlacing
4379 row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
4380 /* Calculate the maximum bytes needed, adding a byte and a pixel
4381 * for safety's sake
4383 row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
4384 1 + ((max_pixel_depth + 7) >> 3);
4386 #ifdef PNG_MAX_MALLOC_64K
4387 if (row_bytes > (png_uint_32)65536L)
4388 png_error(png_ptr, "This image requires a row greater than 64KB");
4389 #endif
4391 if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
4393 png_free(png_ptr, png_ptr->big_row_buf);
4394 png_free(png_ptr, png_ptr->big_prev_row);
4396 if (png_ptr->interlaced)
4397 png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
4398 row_bytes + 48);
4400 else
4401 png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4403 png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4405 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
4406 /* Use 16-byte aligned memory for row_buf with at least 16 bytes
4407 * of padding before and after row_buf; treat prev_row similarly.
4408 * NOTE: the alignment is to the start of the pixels, one beyond the start
4409 * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this
4410 * was incorrect; the filter byte was aligned, which had the exact
4411 * opposite effect of that intended.
4414 png_bytep temp = png_ptr->big_row_buf + 32;
4415 int extra = (int)((temp - (png_bytep)0) & 0x0f);
4416 png_ptr->row_buf = temp - extra - 1/*filter byte*/;
4418 temp = png_ptr->big_prev_row + 32;
4419 extra = (int)((temp - (png_bytep)0) & 0x0f);
4420 png_ptr->prev_row = temp - extra - 1/*filter byte*/;
4423 #else
4424 /* Use 31 bytes of padding before and 17 bytes after row_buf. */
4425 png_ptr->row_buf = png_ptr->big_row_buf + 31;
4426 png_ptr->prev_row = png_ptr->big_prev_row + 31;
4427 #endif
4428 png_ptr->old_big_row_buf_size = row_bytes + 48;
4431 #ifdef PNG_MAX_MALLOC_64K
4432 if (png_ptr->rowbytes > 65535)
4433 png_error(png_ptr, "This image requires a row greater than 64KB");
4435 #endif
4436 if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
4437 png_error(png_ptr, "Row has too many bytes to allocate in memory");
4439 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4441 png_debug1(3, "width = %u,", png_ptr->width);
4442 png_debug1(3, "height = %u,", png_ptr->height);
4443 png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
4444 png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
4445 png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
4446 png_debug1(3, "irowbytes = %lu",
4447 (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
4449 /* The sequential reader needs a buffer for IDAT, but the progressive reader
4450 * does not, so free the read buffer now regardless; the sequential reader
4451 * reallocates it on demand.
4453 if (png_ptr->read_buffer)
4455 png_bytep buffer = png_ptr->read_buffer;
4457 png_ptr->read_buffer_size = 0;
4458 png_ptr->read_buffer = NULL;
4459 png_free(png_ptr, buffer);
4462 /* Finally claim the zstream for the inflate of the IDAT data, use the bits
4463 * value from the stream (note that this will result in a fatal error if the
4464 * IDAT stream has a bogus deflate header window_bits value, but this should
4465 * not be happening any longer!)
4467 if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
4468 png_error(png_ptr, png_ptr->zstream.msg);
4470 png_ptr->flags |= PNG_FLAG_ROW_INIT;
4472 #endif /* PNG_READ_SUPPORTED */