2 /* pngrutil.c - utilities to read a PNG file
4 * Last changed in libpng 1.6.0 [(PENDING RELEASE)]
5 * Copyright (c) 1998-2012 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.
19 #ifdef PNG_READ_SUPPORTED
21 #define png_strtod(p,a,b) strtod(a,b)
24 png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
26 png_uint_32 uval = png_get_uint_32(buf);
28 if (uval > PNG_UINT_31_MAX)
29 png_error(png_ptr, "PNG unsigned integer out of range");
34 #if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
35 /* The following is a variation on the above for use with the fixed
36 * point values used for gAMA and cHRM. Instead of png_error it
37 * issues a warning and returns (-1) - an invalid value because both
38 * gAMA and cHRM use *unsigned* integers for fixed point values.
40 #define PNG_FIXED_ERROR (-1)
42 static png_fixed_point /* PRIVATE */
43 png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
45 png_uint_32 uval = png_get_uint_32(buf);
47 if (uval <= PNG_UINT_31_MAX)
48 return (png_fixed_point)uval; /* known to be in range */
50 /* The caller can turn off the warning by passing NULL. */
52 png_warning(png_ptr, "PNG fixed point integer out of range");
54 return PNG_FIXED_ERROR;
58 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
59 /* NOTE: the read macros will obscure these definitions, so that if
60 * PNG_USE_READ_MACROS is set the library will not use them internally,
61 * but the APIs will still be available externally.
63 * The parentheses around "PNGAPI function_name" in the following three
64 * functions are necessary because they allow the macros to co-exist with
65 * these (unused but exported) functions.
68 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
70 png_get_uint_32)(png_const_bytep buf)
73 ((png_uint_32)(*(buf )) << 24) +
74 ((png_uint_32)(*(buf + 1)) << 16) +
75 ((png_uint_32)(*(buf + 2)) << 8) +
76 ((png_uint_32)(*(buf + 3)) ) ;
81 /* Grab a signed 32-bit integer from a buffer in big-endian format. The
82 * data is stored in the PNG file in two's complement format and there
83 * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
84 * the following code does a two's complement to native conversion.
87 png_get_int_32)(png_const_bytep buf)
89 png_uint_32 uval = png_get_uint_32(buf);
90 if ((uval & 0x80000000) == 0) /* non-negative */
93 uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */
94 return -(png_int_32)uval;
97 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
99 png_get_uint_16)(png_const_bytep buf)
101 /* ANSI-C requires an int value to accomodate at least 16 bits so this
102 * works and allows the compiler not to worry about possible narrowing
103 * on 32 bit systems. (Pre-ANSI systems did not make integers smaller
104 * than 16 bits either.)
107 ((unsigned int)(*buf) << 8) +
108 ((unsigned int)(*(buf + 1)));
110 return (png_uint_16)val;
113 #endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
115 /* Read and check the PNG file signature */
117 png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
119 png_size_t num_checked, num_to_check;
121 /* Exit if the user application does not expect a signature. */
122 if (png_ptr->sig_bytes >= 8)
125 num_checked = png_ptr->sig_bytes;
126 num_to_check = 8 - num_checked;
128 #ifdef PNG_IO_STATE_SUPPORTED
129 png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
132 /* The signature must be serialized in a single I/O call. */
133 png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
134 png_ptr->sig_bytes = 8;
136 if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
138 if (num_checked < 4 &&
139 png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
140 png_error(png_ptr, "Not a PNG file");
142 png_error(png_ptr, "PNG file corrupted by ASCII conversion");
145 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
148 /* Read the chunk header (length + type name).
149 * Put the type name into png_ptr->chunk_name, and return the length.
151 png_uint_32 /* PRIVATE */
152 png_read_chunk_header(png_structrp png_ptr)
157 #ifdef PNG_IO_STATE_SUPPORTED
158 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
161 /* Read the length and the chunk name.
162 * This must be performed in a single I/O call.
164 png_read_data(png_ptr, buf, 8);
165 length = png_get_uint_31(png_ptr, buf);
167 /* Put the chunk name into png_ptr->chunk_name. */
168 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
170 png_debug2(0, "Reading %lx chunk, length = %lu",
171 (unsigned long)png_ptr->chunk_name, (unsigned long)length);
173 /* Reset the crc and run it over the chunk name. */
174 png_reset_crc(png_ptr);
175 png_calculate_crc(png_ptr, buf + 4, 4);
177 /* Check to see if chunk name is valid. */
178 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
180 #ifdef PNG_IO_STATE_SUPPORTED
181 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
187 /* Read data, and (optionally) run it through the CRC. */
189 png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
194 png_read_data(png_ptr, buf, length);
195 png_calculate_crc(png_ptr, buf, length);
198 /* Optionally skip data and then check the CRC. Depending on whether we
199 * are reading an ancillary or critical chunk, and how the program has set
200 * things up, we may calculate the CRC on the data and print a message.
201 * Returns '1' if there was a CRC error, '0' otherwise.
204 png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
206 /* The size of the local buffer for inflate is a good guess as to a
207 * reasonable size to use for buffering reads from the application.
212 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
214 len = (sizeof tmpbuf);
219 png_crc_read(png_ptr, tmpbuf, len);
222 if (png_crc_error(png_ptr))
224 if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name) ?
225 !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
226 (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
228 png_chunk_warning(png_ptr, "CRC error");
233 png_chunk_benign_error(png_ptr, "CRC error");
243 /* Compare the CRC stored in the PNG file with that calculated by libpng from
244 * the data it has read thus far.
247 png_crc_error(png_structrp png_ptr)
249 png_byte crc_bytes[4];
253 if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name))
255 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
256 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
262 if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
266 #ifdef PNG_IO_STATE_SUPPORTED
267 png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
270 /* The chunk CRC must be serialized in a single I/O call. */
271 png_read_data(png_ptr, crc_bytes, 4);
275 crc = png_get_uint_32(crc_bytes);
276 return ((int)(crc != png_ptr->crc));
283 /* Manage the read buffer; this simply reallocates the buffer if it is not small
284 * enough (or if it is not allocated). The routine returns a pointer to the
285 * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
286 * it will call png_error (via png_malloc) on failure. (warn == 2 means
290 png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
292 png_bytep buffer = png_ptr->read_buffer;
294 if (buffer != NULL && new_size > png_ptr->read_buffer_size)
296 png_ptr->read_buffer = NULL;
297 png_ptr->read_buffer = NULL;
298 png_ptr->read_buffer_size = 0;
299 png_free(png_ptr, buffer);
305 buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
309 png_ptr->read_buffer = buffer;
310 png_ptr->read_buffer_size = new_size;
313 else if (warn < 2) /* else silent */
315 #ifdef PNG_WARNINGS_SUPPORTED
317 png_chunk_warning(png_ptr, "insufficient memory to read chunk");
321 #ifdef PNG_ERROR_TEXT_SUPPORTED
322 png_chunk_error(png_ptr, "insufficient memory to read chunk");
331 /* png_inflate_claim: claim the zstream for some nefarious purpose that involves
332 * decompression. Returns Z_OK on success, else a zlib error code. It checks
333 * the owner but, in final release builds, just issues a warning if some other
334 * chunk apparently owns the stream. Prior to release it does a png_error.
337 png_inflate_claim(png_structrp png_ptr, png_uint_32 owner, int window_bits)
339 if (png_ptr->zowner != 0)
343 PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
344 /* So the message that results is "<chunk> using zstream"; this is an
345 * internal error, but is very useful for debugging. i18n requirements
348 (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
349 # if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
350 png_chunk_warning(png_ptr, msg);
353 png_chunk_error(png_ptr, msg);
357 /* Implementation note: unlike 'png_deflate_claim' this internal function
358 * does not take the size of the data as an argument. Some efficiency could
359 * be gained by using this when it is known *if* the zlib stream itself does
360 * not record the number; however, this is an illusion: the original writer
361 * of the PNG may have selected a lower window size, and we really must
362 * follow that because, for systems with with limited capabilities, we
363 * would otherwise reject the application's attempts to use a smaller window
364 * size (zlib doesn't have an interface to say "this or lower"!).
366 * inflateReset2 was added to zlib 1.2.4; before this the window could not be
367 * reset, therefore it is necessary to always allocate the maximum window
368 * size with earlier zlibs just in case later compressed chunks need it.
371 int ret; /* zlib return code */
373 /* Set this for safety, just in case the previous owner left pointers to
374 * memory allocations.
376 png_ptr->zstream.next_in = NULL;
377 png_ptr->zstream.avail_in = 0;
378 png_ptr->zstream.next_out = NULL;
379 png_ptr->zstream.avail_out = 0;
381 if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
383 # if ZLIB_VERNUM < 0x1240
384 PNG_UNUSED(window_bits)
385 ret = inflateReset(&png_ptr->zstream);
387 ret = inflateReset2(&png_ptr->zstream, window_bits);
393 # if ZLIB_VERNUM < 0x1240
394 ret = inflateInit(&png_ptr->zstream);
396 ret = inflateInit2(&png_ptr->zstream, window_bits);
400 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
404 png_ptr->zowner = owner;
407 png_zstream_error(png_ptr, ret);
413 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
414 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
415 * allow the caller to do multiple calls if required. If the 'finish' flag is
416 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
417 * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
418 * Z_OK or Z_STREAM_END will be returned on success.
420 * The input and output sizes are updated to the actual amounts of data consumed
421 * or written, not the amount available (as in a z_stream). The data pointers
422 * are not changed, so the next input is (data+input_size) and the next
423 * available output is (output+output_size).
426 png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
427 /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
428 /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
430 if (png_ptr->zowner == owner) /* Else not claimed */
433 png_alloc_size_t avail_out = *output_size_ptr;
434 png_uint_32 avail_in = *input_size_ptr;
436 /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
437 * can't even necessarily handle 65536 bytes) because the type uInt is
438 * "16 bits or more". Consequently it is necessary to chunk the input to
439 * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
440 * maximum value that can be stored in a uInt.) It is possible to set
441 * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
442 * a performance advantage, because it reduces the amount of data accessed
443 * at each step and that may give the OS more time to page it in.
445 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
446 /* avail_in and avail_out are set below from 'size' */
447 png_ptr->zstream.avail_in = 0;
448 png_ptr->zstream.avail_out = 0;
450 /* Read directly into the output if it is available (this is set to
451 * a local buffer below if output is NULL).
454 png_ptr->zstream.next_out = output;
459 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
461 /* zlib INPUT BUFFER */
462 /* The setting of 'avail_in' used to be outside the loop; by setting it
463 * inside it is possible to chunk the input to zlib and simply rely on
464 * zlib to advance the 'next_in' pointer. This allows arbitrary
465 * amounts of data to be passed through zlib at the unavoidable cost of
466 * requiring a window save (memcpy of up to 32768 output bytes)
467 * every ZLIB_IO_MAX input bytes.
469 avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
473 if (avail_in < avail)
474 avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
477 png_ptr->zstream.avail_in = avail;
479 /* zlib OUTPUT BUFFER */
480 avail_out += png_ptr->zstream.avail_out; /* not written last time */
482 avail = ZLIB_IO_MAX; /* maximum zlib can process */
486 /* Reset the output buffer each time round if output is NULL and
487 * make available the full buffer, up to 'remaining_space'
489 png_ptr->zstream.next_out = local_buffer;
490 if ((sizeof local_buffer) < avail)
491 avail = (sizeof local_buffer);
494 if (avail_out < avail)
495 avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
497 png_ptr->zstream.avail_out = avail;
500 /* zlib inflate call */
501 /* In fact 'avail_out' may be 0 at this point, that happens at the end
502 * of the read when the final LZ end code was not passed at the end of
503 * the previous chunk of input data. Tell zlib if we have reached the
504 * end of the output buffer.
506 ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH :
507 (finish ? Z_FINISH : Z_SYNC_FLUSH));
508 } while (ret == Z_OK);
510 /* For safety kill the local buffer pointer now */
512 png_ptr->zstream.next_out = NULL;
514 /* Claw back the 'size' and 'remaining_space' byte counts. */
515 avail_in += png_ptr->zstream.avail_in;
516 avail_out += png_ptr->zstream.avail_out;
518 /* Update the input and output sizes; the updated values are the amount
519 * consumed or written, effectively the inverse of what zlib uses.
522 *output_size_ptr -= avail_out;
525 *input_size_ptr -= avail_in;
527 /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
528 png_zstream_error(png_ptr, ret);
534 /* This is a bad internal error. The recovery assigns to the zstream msg
535 * pointer, which is not owned by the caller, but this is safe; it's only
538 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
539 return Z_STREAM_ERROR;
544 * Decompress trailing data in a chunk. The assumption is that read_buffer
545 * points at an allocated area holding the contents of a chunk with a
546 * trailing compressed part. What we get back is an allocated area
547 * holding the original prefix part and an uncompressed version of the
548 * trailing part (the malloc area passed in is freed).
551 png_decompress_chunk(png_structrp png_ptr,
552 png_uint_32 chunklength, png_uint_32 prefix_size,
553 png_alloc_size_t *newlength /* must be initialized to the maximum! */,
554 int terminate /*add a '\0' to the end of the uncompressed data*/)
556 /* TODO: implement different limits for different types of chunk.
558 * The caller supplies *newlength set to the maximum length of the
559 * uncompressed data, but this routine allocates space for the prefix and
560 * maybe a '\0' terminator too. We have to assume that 'prefix_size' is
561 * limited only by the maximum chunk size.
563 png_alloc_size_t limit = PNG_SIZE_MAX;
565 # ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
566 if (png_ptr->user_chunk_malloc_max > 0 &&
567 png_ptr->user_chunk_malloc_max < limit)
568 limit = png_ptr->user_chunk_malloc_max;
569 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
570 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
571 limit = PNG_USER_CHUNK_MALLOC_MAX;
574 if (limit >= prefix_size + (terminate != 0))
578 limit -= prefix_size + (terminate != 0);
580 if (limit < *newlength)
583 /* Now try to claim the stream; the 'warn' setting causes zlib to be told
584 * to use the maximum window size during inflate; this hides errors in the
585 * deflate header window bits value which is used if '0' is passed. In
586 * fact this only has an effect with zlib versions 1.2.4 and later - see
587 * the comments in png_inflate_claim above.
589 ret = png_inflate_claim(png_ptr, png_ptr->chunk_name,
590 png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN ? 15 : 0);
594 png_uint_32 lzsize = chunklength - prefix_size;
596 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
597 /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
598 /* output: */ NULL, newlength);
600 if (ret == Z_STREAM_END)
602 /* Use 'inflateReset' here, not 'inflateReset2' because this
603 * preserves the previously decided window size (otherwise it would
604 * be necessary to store the previous window size.) In practice
605 * this doesn't matter anyway, because png_inflate will call inflate
606 * with Z_FINISH in almost all cases, so the window will not be
609 if (inflateReset(&png_ptr->zstream) == Z_OK)
611 /* Because of the limit checks above we know that the new,
612 * expanded, size will fit in a size_t (let alone an
613 * png_alloc_size_t). Use png_malloc_base here to avoid an
616 png_alloc_size_t new_size = *newlength;
617 png_alloc_size_t buffer_size = prefix_size + new_size +
619 png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
624 ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
625 png_ptr->read_buffer + prefix_size, &lzsize,
626 text + prefix_size, newlength);
628 if (ret == Z_STREAM_END)
630 if (new_size == *newlength)
633 text[prefix_size + *newlength] = 0;
636 memcpy(text, png_ptr->read_buffer, prefix_size);
639 png_bytep old_ptr = png_ptr->read_buffer;
641 png_ptr->read_buffer = text;
642 png_ptr->read_buffer_size = buffer_size;
643 text = old_ptr; /* freed below */
649 /* The size changed on the second read, there can be no
650 * guarantee that anything is correct at this point.
651 * The 'msg' pointer has been set to "unexpected end of
652 * LZ stream", which is fine, but return an error code
653 * that the caller won't accept.
655 ret = PNG_UNEXPECTED_ZLIB_RETURN;
659 else if (ret == Z_OK)
660 ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
662 /* Free the text pointer (this is the old read_buffer on
665 png_free(png_ptr, text);
667 /* This really is very benign, but it's still an error because
668 * the extra space may otherwise be used as a Trojan Horse.
670 if (ret == Z_STREAM_END &&
671 chunklength - prefix_size != lzsize)
672 png_chunk_benign_error(png_ptr, "extra compressed data");
677 /* Out of memory allocating the buffer */
679 png_zstream_error(png_ptr, Z_MEM_ERROR);
685 /* inflateReset failed, store the error message */
686 png_zstream_error(png_ptr, ret);
688 if (ret == Z_STREAM_END)
689 ret = PNG_UNEXPECTED_ZLIB_RETURN;
693 else if (ret == Z_OK)
694 ret = PNG_UNEXPECTED_ZLIB_RETURN;
696 /* Release the claimed stream */
700 else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
701 ret = PNG_UNEXPECTED_ZLIB_RETURN;
708 /* Application/configuration limits exceeded */
709 png_zstream_error(png_ptr, Z_MEM_ERROR);
713 #endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
715 #ifdef PNG_READ_iCCP_SUPPORTED
716 /* Perform a partial read and decompress, producing 'avail_out' bytes and
717 * reading from the current chunk as required.
720 png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
721 png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
724 if (png_ptr->zowner == png_ptr->chunk_name)
728 /* next_in and avail_in must have been initialized by the caller. */
729 png_ptr->zstream.next_out = next_out;
730 png_ptr->zstream.avail_out = 0; /* set in the loop */
734 if (png_ptr->zstream.avail_in == 0)
736 if (read_size > *chunk_bytes)
737 read_size = (uInt)*chunk_bytes;
738 *chunk_bytes -= read_size;
741 png_crc_read(png_ptr, read_buffer, read_size);
743 png_ptr->zstream.next_in = read_buffer;
744 png_ptr->zstream.avail_in = read_size;
747 if (png_ptr->zstream.avail_out == 0)
749 uInt avail = ZLIB_IO_MAX;
750 if (avail > *out_size)
751 avail = (uInt)*out_size;
754 png_ptr->zstream.avail_out = avail;
757 /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
758 * the available output is produced; this allows reading of truncated
761 ret = inflate(&png_ptr->zstream,
762 *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
764 while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
766 *out_size += png_ptr->zstream.avail_out;
767 png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
769 /* Ensure the error message pointer is always set: */
770 png_zstream_error(png_ptr, ret);
776 png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
777 return Z_STREAM_ERROR;
782 /* Read and check the IDHR chunk */
784 png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
787 png_uint_32 width, height;
788 int bit_depth, color_type, compression_type, filter_type;
791 png_debug(1, "in png_handle_IHDR");
793 if (png_ptr->mode & PNG_HAVE_IHDR)
794 png_chunk_error(png_ptr, "out of place");
796 /* Check the length */
798 png_chunk_error(png_ptr, "invalid");
800 png_ptr->mode |= PNG_HAVE_IHDR;
802 png_crc_read(png_ptr, buf, 13);
803 png_crc_finish(png_ptr, 0);
805 width = png_get_uint_31(png_ptr, buf);
806 height = png_get_uint_31(png_ptr, buf + 4);
809 compression_type = buf[10];
810 filter_type = buf[11];
811 interlace_type = buf[12];
813 /* Set internal variables */
814 png_ptr->width = width;
815 png_ptr->height = height;
816 png_ptr->bit_depth = (png_byte)bit_depth;
817 png_ptr->interlaced = (png_byte)interlace_type;
818 png_ptr->color_type = (png_byte)color_type;
819 #ifdef PNG_MNG_FEATURES_SUPPORTED
820 png_ptr->filter_type = (png_byte)filter_type;
822 png_ptr->compression_type = (png_byte)compression_type;
824 /* Find number of channels */
825 switch (png_ptr->color_type)
827 default: /* invalid, png_set_IHDR calls png_error */
828 case PNG_COLOR_TYPE_GRAY:
829 case PNG_COLOR_TYPE_PALETTE:
830 png_ptr->channels = 1;
833 case PNG_COLOR_TYPE_RGB:
834 png_ptr->channels = 3;
837 case PNG_COLOR_TYPE_GRAY_ALPHA:
838 png_ptr->channels = 2;
841 case PNG_COLOR_TYPE_RGB_ALPHA:
842 png_ptr->channels = 4;
846 /* Set up other useful info */
847 png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
849 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
850 png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
851 png_debug1(3, "channels = %d", png_ptr->channels);
852 png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
853 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
854 color_type, interlace_type, compression_type, filter_type);
857 /* Read and check the palette */
859 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
861 png_color palette[PNG_MAX_PALETTE_LENGTH];
863 #ifdef PNG_POINTER_INDEXING_SUPPORTED
867 png_debug(1, "in png_handle_PLTE");
869 if (!(png_ptr->mode & PNG_HAVE_IHDR))
870 png_chunk_error(png_ptr, "missing IHDR");
872 /* Moved to before the 'after IDAT' check below because otherwise duplicate
873 * PLTE chunks are potentially ignored (the spec says there shall not be more
874 * than one PLTE, the error is not treated as benign, so this check trumps
875 * the requirement that PLTE appears before IDAT.)
877 else if (png_ptr->mode & PNG_HAVE_PLTE)
878 png_chunk_error(png_ptr, "duplicate");
880 else if (png_ptr->mode & PNG_HAVE_IDAT)
882 /* This is benign because the non-benign error happened before, when an
883 * IDAT was encountered in a color-mapped image with no PLTE.
885 png_crc_finish(png_ptr, length);
886 png_chunk_benign_error(png_ptr, "out of place");
890 png_ptr->mode |= PNG_HAVE_PLTE;
892 if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
894 png_crc_finish(png_ptr, length);
895 png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
899 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
900 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
902 png_crc_finish(png_ptr, length);
907 if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
909 png_crc_finish(png_ptr, length);
911 if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
912 png_chunk_benign_error(png_ptr, "invalid");
915 png_chunk_error(png_ptr, "invalid");
920 /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
921 num = (int)length / 3;
923 #ifdef PNG_POINTER_INDEXING_SUPPORTED
924 for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
928 png_crc_read(png_ptr, buf, 3);
929 pal_ptr->red = buf[0];
930 pal_ptr->green = buf[1];
931 pal_ptr->blue = buf[2];
934 for (i = 0; i < num; i++)
938 png_crc_read(png_ptr, buf, 3);
939 /* Don't depend upon png_color being any order */
940 palette[i].red = buf[0];
941 palette[i].green = buf[1];
942 palette[i].blue = buf[2];
946 /* If we actually need the PLTE chunk (ie for a paletted image), we do
947 * whatever the normal CRC configuration tells us. However, if we
948 * have an RGB image, the PLTE can be considered ancillary, so
949 * we will act as though it is.
951 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
952 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
955 png_crc_finish(png_ptr, 0);
958 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
959 else if (png_crc_error(png_ptr)) /* Only if we have a CRC error */
961 /* If we don't want to use the data from an ancillary chunk,
962 * we have two options: an error abort, or a warning and we
963 * ignore the data in this chunk (which should be OK, since
964 * it's considered ancillary for a RGB or RGBA image).
966 * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
967 * chunk type to determine whether to check the ancillary or the critical
970 if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
972 if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
974 png_chunk_benign_error(png_ptr, "CRC error");
979 png_chunk_warning(png_ptr, "CRC error");
984 /* Otherwise, we (optionally) emit a warning and use the chunk. */
985 else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
987 png_chunk_warning(png_ptr, "CRC error");
992 /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
993 * own copy of the palette. This has the side effect that when png_start_row
994 * is called (this happens after any call to png_read_update_info) the
995 * info_ptr palette gets changed. This is extremely unexpected and
998 * Fix this by not sharing the palette in this way.
1000 png_set_PLTE(png_ptr, info_ptr, palette, num);
1002 /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
1003 * IDAT. Prior to 1.6.0 this was not checked; instead the code merely
1004 * checked the apparent validity of a tRNS chunk inserted before PLTE on a
1005 * palette PNG. 1.6.0 attempts to rigorously follow the standard and
1006 * therefore does a benign error if the erroneous condition is detected *and*
1007 * cancels the tRNS if the benign error returns. The alternative is to
1008 * amend the standard since it would be rather hypocritical of the standards
1009 * maintainers to ignore it.
1011 #ifdef PNG_READ_tRNS_SUPPORTED
1012 if (png_ptr->num_trans > 0 ||
1013 (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
1015 /* Cancel this because otherwise it would be used if the transforms
1016 * require it. Don't cancel the 'valid' flag because this would prevent
1017 * detection of duplicate chunks.
1019 png_ptr->num_trans = 0;
1021 if (info_ptr != NULL)
1022 info_ptr->num_trans = 0;
1024 png_chunk_benign_error(png_ptr, "tRNS must be after");
1028 #ifdef PNG_READ_hIST_SUPPORTED
1029 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
1030 png_chunk_benign_error(png_ptr, "hIST must be after");
1033 #ifdef PNG_READ_bKGD_SUPPORTED
1034 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
1035 png_chunk_benign_error(png_ptr, "bKGD must be after");
1040 png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1042 png_debug(1, "in png_handle_IEND");
1044 if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
1045 png_chunk_error(png_ptr, "out of place");
1047 png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
1049 png_crc_finish(png_ptr, length);
1052 png_chunk_benign_error(png_ptr, "invalid");
1054 PNG_UNUSED(info_ptr)
1057 #ifdef PNG_READ_gAMA_SUPPORTED
1059 png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1061 png_fixed_point igamma;
1064 png_debug(1, "in png_handle_gAMA");
1066 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1067 png_chunk_error(png_ptr, "missing IHDR");
1069 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1071 png_crc_finish(png_ptr, length);
1072 png_chunk_benign_error(png_ptr, "out of place");
1078 png_crc_finish(png_ptr, length);
1079 png_chunk_benign_error(png_ptr, "invalid");
1083 png_crc_read(png_ptr, buf, 4);
1085 if (png_crc_finish(png_ptr, 0))
1088 igamma = png_get_fixed_point(NULL, buf);
1090 png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
1091 png_colorspace_sync(png_ptr, info_ptr);
1095 #ifdef PNG_READ_sBIT_SUPPORTED
1097 png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1099 unsigned int truelen;
1102 png_debug(1, "in png_handle_sBIT");
1104 buf[0] = buf[1] = buf[2] = buf[3] = 0;
1106 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1107 png_chunk_error(png_ptr, "missing IHDR");
1109 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1111 png_crc_finish(png_ptr, length);
1112 png_chunk_benign_error(png_ptr, "out of place");
1116 if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
1118 png_crc_finish(png_ptr, length);
1119 png_chunk_benign_error(png_ptr, "duplicate");
1123 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1127 truelen = png_ptr->channels;
1129 if (length != truelen || length > 4)
1131 png_chunk_benign_error(png_ptr, "invalid");
1132 png_crc_finish(png_ptr, length);
1136 png_crc_read(png_ptr, buf, truelen);
1138 if (png_crc_finish(png_ptr, 0))
1141 if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
1143 png_ptr->sig_bit.red = buf[0];
1144 png_ptr->sig_bit.green = buf[1];
1145 png_ptr->sig_bit.blue = buf[2];
1146 png_ptr->sig_bit.alpha = buf[3];
1151 png_ptr->sig_bit.gray = buf[0];
1152 png_ptr->sig_bit.red = buf[0];
1153 png_ptr->sig_bit.green = buf[0];
1154 png_ptr->sig_bit.blue = buf[0];
1155 png_ptr->sig_bit.alpha = buf[1];
1158 png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
1162 #ifdef PNG_READ_cHRM_SUPPORTED
1164 png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1169 png_debug(1, "in png_handle_cHRM");
1171 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1172 png_chunk_error(png_ptr, "missing IHDR");
1174 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1176 png_crc_finish(png_ptr, length);
1177 png_chunk_benign_error(png_ptr, "out of place");
1183 png_crc_finish(png_ptr, length);
1184 png_chunk_benign_error(png_ptr, "invalid");
1188 png_crc_read(png_ptr, buf, 32);
1190 if (png_crc_finish(png_ptr, 0))
1193 xy.whitex = png_get_fixed_point(NULL, buf);
1194 xy.whitey = png_get_fixed_point(NULL, buf + 4);
1195 xy.redx = png_get_fixed_point(NULL, buf + 8);
1196 xy.redy = png_get_fixed_point(NULL, buf + 12);
1197 xy.greenx = png_get_fixed_point(NULL, buf + 16);
1198 xy.greeny = png_get_fixed_point(NULL, buf + 20);
1199 xy.bluex = png_get_fixed_point(NULL, buf + 24);
1200 xy.bluey = png_get_fixed_point(NULL, buf + 28);
1202 if (xy.whitex == PNG_FIXED_ERROR ||
1203 xy.whitey == PNG_FIXED_ERROR ||
1204 xy.redx == PNG_FIXED_ERROR ||
1205 xy.redy == PNG_FIXED_ERROR ||
1206 xy.greenx == PNG_FIXED_ERROR ||
1207 xy.greeny == PNG_FIXED_ERROR ||
1208 xy.bluex == PNG_FIXED_ERROR ||
1209 xy.bluey == PNG_FIXED_ERROR)
1211 png_chunk_benign_error(png_ptr, "invalid values");
1215 /* If a colorspace error has already been output skip this chunk */
1216 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1219 if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM)
1221 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1222 png_colorspace_sync(png_ptr, info_ptr);
1223 png_chunk_benign_error(png_ptr, "duplicate");
1227 png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
1228 (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1229 1/*prefer cHRM values*/);
1230 png_colorspace_sync(png_ptr, info_ptr);
1234 #ifdef PNG_READ_sRGB_SUPPORTED
1236 png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1240 png_debug(1, "in png_handle_sRGB");
1242 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1243 png_chunk_error(png_ptr, "missing IHDR");
1245 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1247 png_crc_finish(png_ptr, length);
1248 png_chunk_benign_error(png_ptr, "out of place");
1254 png_crc_finish(png_ptr, length);
1255 png_chunk_benign_error(png_ptr, "invalid");
1259 png_crc_read(png_ptr, &intent, 1);
1261 if (png_crc_finish(png_ptr, 0))
1264 /* If a colorspace error has already been output skip this chunk */
1265 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1268 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1271 if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT)
1273 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1274 png_colorspace_sync(png_ptr, info_ptr);
1275 png_chunk_benign_error(png_ptr, "too many profiles");
1279 (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
1280 png_colorspace_sync(png_ptr, info_ptr);
1282 #endif /* PNG_READ_sRGB_SUPPORTED */
1284 #ifdef PNG_READ_iCCP_SUPPORTED
1286 png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1287 /* Note: this does not properly handle profiles that are > 64K under DOS */
1289 png_const_charp errmsg = NULL; /* error message output, or no error */
1290 int finished = 0; /* crc checked */
1292 png_debug(1, "in png_handle_iCCP");
1294 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1295 png_chunk_error(png_ptr, "missing IHDR");
1297 else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
1299 png_crc_finish(png_ptr, length);
1300 png_chunk_benign_error(png_ptr, "out of place");
1304 /* Consistent with all the above colorspace handling an obviously *invalid*
1305 * chunk is just ignored, so does not invalidate the color space. An
1306 * alternative is to set the 'invalid' flags at the start of this routine
1307 * and only clear them in they were not set before and all the tests pass.
1308 * The minimum 'deflate' stream is assumed to be just the 2 byte header and 4
1309 * byte checksum. The keyword must be one character and there is a
1310 * terminator (0) byte and the compression method.
1314 png_crc_finish(png_ptr, length);
1315 png_chunk_benign_error(png_ptr, "too short");
1319 /* If a colorspace error has already been output skip this chunk */
1320 if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
1322 png_crc_finish(png_ptr, length);
1326 /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
1329 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
1331 uInt read_length, keyword_length;
1334 /* Find the keyword; the keyword plus separator and compression method
1335 * bytes can be at most 81 characters long.
1337 read_length = 81; /* maximum */
1338 if (read_length > length)
1339 read_length = (uInt)length;
1341 png_crc_read(png_ptr, (png_bytep)keyword, read_length);
1342 length -= read_length;
1345 while (keyword_length < 80 && keyword_length < read_length &&
1346 keyword[keyword_length] != 0)
1349 /* TODO: make the keyword checking common */
1350 if (keyword_length >= 1 && keyword_length <= 79)
1352 /* We only understand '0' compression - deflate - so if we get a
1353 * different value we can't safely decode the chunk.
1355 if (keyword_length+1 < read_length &&
1356 keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
1358 read_length -= keyword_length+2;
1360 if (png_inflate_claim(png_ptr, png_iCCP,
1361 png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN ? 15 : 0) == Z_OK)
1363 Byte profile_header[132];
1364 Byte local_buffer[PNG_INFLATE_BUF_SIZE];
1365 png_alloc_size_t size = (sizeof profile_header);
1367 png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
1368 png_ptr->zstream.avail_in = read_length;
1369 (void)png_inflate_read(png_ptr, local_buffer,
1370 (sizeof local_buffer), &length, profile_header, &size,
1371 0/*finish: don't, because the output is too small*/);
1375 /* We have the ICC profile header; do the basic header checks.
1377 const png_uint_32 profile_length =
1378 png_get_uint_32(profile_header);
1380 if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
1381 keyword, profile_length))
1383 /* The length is apparently ok, so we can check the 132
1386 if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
1387 keyword, profile_length, profile_header,
1388 png_ptr->color_type))
1390 /* Now read the tag table; a variable size buffer is
1391 * needed at this point, allocate one for the whole
1392 * profile. The header check has already validated
1393 * that none of these stuff will overflow.
1395 const png_uint_32 tag_count = png_get_uint_32(
1396 profile_header+128);
1397 png_bytep profile = png_read_buffer(png_ptr,
1398 profile_length, 2/*silent*/);
1400 if (profile != NULL)
1402 memcpy(profile, profile_header,
1403 (sizeof profile_header));
1405 size = 12 * tag_count;
1407 (void)png_inflate_read(png_ptr, local_buffer,
1408 (sizeof local_buffer), &length,
1409 profile + (sizeof profile_header), &size, 0);
1411 /* Still expect a a buffer error because we expect
1412 * there to be some tag data!
1416 if (png_icc_check_tag_table(png_ptr,
1417 &png_ptr->colorspace, keyword, profile_length,
1420 /* The profile has been validated for basic
1421 * security issues, so read the whole thing in.
1423 size = profile_length - (sizeof profile_header)
1426 (void)png_inflate_read(png_ptr, local_buffer,
1427 (sizeof local_buffer), &length,
1428 profile + (sizeof profile_header) +
1429 12 * tag_count, &size, 1/*finish*/);
1431 if (length > 0 && !(png_ptr->flags &
1432 PNG_FLAG_BENIGN_ERRORS_WARN))
1433 errmsg = "extra compressed data";
1435 /* But otherwise allow extra data: */
1440 /* This can be handled completely, so
1443 png_chunk_warning(png_ptr,
1444 "extra compressed data");
1447 png_crc_finish(png_ptr, length);
1450 # ifdef PNG_sRGB_SUPPORTED
1451 /* Check for a match against sRGB */
1452 png_icc_set_sRGB(png_ptr,
1453 &png_ptr->colorspace, profile,
1454 png_ptr->zstream.adler);
1457 /* Steal the profile for info_ptr. */
1458 if (info_ptr != NULL)
1460 png_free_data(png_ptr, info_ptr,
1463 info_ptr->iccp_name = png_voidcast(char*,
1464 png_malloc_base(png_ptr,
1466 if (info_ptr->iccp_name != NULL)
1468 memcpy(info_ptr->iccp_name, keyword,
1470 info_ptr->iccp_proflen =
1472 info_ptr->iccp_profile = profile;
1473 png_ptr->read_buffer = NULL; /*steal*/
1474 info_ptr->free_me |= PNG_FREE_ICCP;
1475 info_ptr->valid |= PNG_INFO_iCCP;
1480 png_ptr->colorspace.flags |=
1481 PNG_COLORSPACE_INVALID;
1482 errmsg = "out of memory";
1486 /* else the profile remains in the read
1487 * buffer which gets reused for subsequent
1491 if (info_ptr != NULL)
1492 png_colorspace_sync(png_ptr, info_ptr);
1496 png_ptr->zowner = 0;
1502 errmsg = "truncated";
1505 errmsg = png_ptr->zstream.msg;
1508 /* else png_icc_check_tag_table output an error */
1511 else /* profile truncated */
1512 errmsg = png_ptr->zstream.msg;
1516 errmsg = "out of memory";
1519 /* else png_icc_check_header output an error */
1522 /* else png_icc_check_length output an error */
1525 else /* profile truncated */
1526 errmsg = png_ptr->zstream.msg;
1528 /* Release the stream */
1529 png_ptr->zowner = 0;
1532 else /* png_inflate_claim failed */
1533 errmsg = png_ptr->zstream.msg;
1537 errmsg = "bad compression method"; /* or missing */
1541 errmsg = "bad keyword";
1545 errmsg = "too many profiles";
1547 /* Failure: the reason is in 'errmsg' */
1549 png_crc_finish(png_ptr, length);
1551 png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
1552 png_colorspace_sync(png_ptr, info_ptr);
1553 if (errmsg != NULL) /* else already output */
1554 png_chunk_benign_error(png_ptr, errmsg);
1556 #endif /* PNG_READ_iCCP_SUPPORTED */
1558 #ifdef PNG_READ_sPLT_SUPPORTED
1560 png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1561 /* Note: this does not properly handle chunks that are > 64K under DOS */
1563 png_bytep entry_start, buffer;
1564 png_sPLT_t new_palette;
1566 png_uint_32 data_length;
1568 png_uint_32 skip = 0;
1572 png_debug(1, "in png_handle_sPLT");
1574 #ifdef PNG_USER_LIMITS_SUPPORTED
1575 if (png_ptr->user_chunk_cache_max != 0)
1577 if (png_ptr->user_chunk_cache_max == 1)
1579 png_crc_finish(png_ptr, length);
1583 if (--png_ptr->user_chunk_cache_max == 1)
1585 png_warning(png_ptr, "No space in chunk cache for sPLT");
1586 png_crc_finish(png_ptr, length);
1592 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1593 png_chunk_error(png_ptr, "missing IHDR");
1595 else if (png_ptr->mode & PNG_HAVE_IDAT)
1597 png_crc_finish(png_ptr, length);
1598 png_chunk_benign_error(png_ptr, "out of place");
1602 #ifdef PNG_MAX_MALLOC_64K
1603 if (length > 65535U)
1605 png_crc_finish(png_ptr, length);
1606 png_chunk_benign_error(png_ptr, "too large to fit in memory");
1611 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
1614 png_crc_finish(png_ptr, length);
1615 png_chunk_benign_error(png_ptr, "out of memory");
1620 /* WARNING: this may break if size_t is less than 32 bits; it is assumed
1621 * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
1622 * potential breakage point if the types in pngconf.h aren't exactly right.
1624 png_crc_read(png_ptr, buffer, length);
1626 if (png_crc_finish(png_ptr, skip))
1631 for (entry_start = buffer; *entry_start; entry_start++)
1632 /* Empty loop to find end of name */ ;
1636 /* A sample depth should follow the separator, and we should be on it */
1637 if (entry_start > buffer + length - 2)
1639 png_warning(png_ptr, "malformed sPLT chunk");
1643 new_palette.depth = *entry_start++;
1644 entry_size = (new_palette.depth == 8 ? 6 : 10);
1645 /* This must fit in a png_uint_32 because it is derived from the original
1646 * chunk data length.
1648 data_length = length - (png_uint_32)(entry_start - buffer);
1650 /* Integrity-check the data length */
1651 if (data_length % entry_size)
1653 png_warning(png_ptr, "sPLT chunk has bad length");
1657 dl = (png_int_32)(data_length / entry_size);
1658 max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
1662 png_warning(png_ptr, "sPLT chunk too long");
1666 new_palette.nentries = (png_int_32)(data_length / entry_size);
1668 new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
1669 png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
1671 if (new_palette.entries == NULL)
1673 png_warning(png_ptr, "sPLT chunk requires too much memory");
1677 #ifdef PNG_POINTER_INDEXING_SUPPORTED
1678 for (i = 0; i < new_palette.nentries; i++)
1680 pp = new_palette.entries + i;
1682 if (new_palette.depth == 8)
1684 pp->red = *entry_start++;
1685 pp->green = *entry_start++;
1686 pp->blue = *entry_start++;
1687 pp->alpha = *entry_start++;
1692 pp->red = png_get_uint_16(entry_start); entry_start += 2;
1693 pp->green = png_get_uint_16(entry_start); entry_start += 2;
1694 pp->blue = png_get_uint_16(entry_start); entry_start += 2;
1695 pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
1698 pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
1701 pp = new_palette.entries;
1703 for (i = 0; i < new_palette.nentries; i++)
1706 if (new_palette.depth == 8)
1708 pp[i].red = *entry_start++;
1709 pp[i].green = *entry_start++;
1710 pp[i].blue = *entry_start++;
1711 pp[i].alpha = *entry_start++;
1716 pp[i].red = png_get_uint_16(entry_start); entry_start += 2;
1717 pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
1718 pp[i].blue = png_get_uint_16(entry_start); entry_start += 2;
1719 pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
1722 pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
1726 /* Discard all chunk data except the name and stash that */
1727 new_palette.name = (png_charp)buffer;
1729 png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
1731 png_free(png_ptr, new_palette.entries);
1733 #endif /* PNG_READ_sPLT_SUPPORTED */
1735 #ifdef PNG_READ_tRNS_SUPPORTED
1737 png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1739 png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
1741 png_debug(1, "in png_handle_tRNS");
1743 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1744 png_chunk_error(png_ptr, "missing IHDR");
1746 else if (png_ptr->mode & PNG_HAVE_IDAT)
1748 png_crc_finish(png_ptr, length);
1749 png_chunk_benign_error(png_ptr, "out of place");
1753 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
1755 png_crc_finish(png_ptr, length);
1756 png_chunk_benign_error(png_ptr, "duplicate");
1760 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
1766 png_crc_finish(png_ptr, length);
1767 png_chunk_benign_error(png_ptr, "invalid");
1771 png_crc_read(png_ptr, buf, 2);
1772 png_ptr->num_trans = 1;
1773 png_ptr->trans_color.gray = png_get_uint_16(buf);
1776 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
1782 png_crc_finish(png_ptr, length);
1783 png_chunk_benign_error(png_ptr, "invalid");
1787 png_crc_read(png_ptr, buf, length);
1788 png_ptr->num_trans = 1;
1789 png_ptr->trans_color.red = png_get_uint_16(buf);
1790 png_ptr->trans_color.green = png_get_uint_16(buf + 2);
1791 png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
1794 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1796 if (!(png_ptr->mode & PNG_HAVE_PLTE))
1798 /* TODO: is this actually an error in the ISO spec? */
1799 png_crc_finish(png_ptr, length);
1800 png_chunk_benign_error(png_ptr, "out of place");
1804 if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH ||
1807 png_crc_finish(png_ptr, length);
1808 png_chunk_benign_error(png_ptr, "invalid");
1812 png_crc_read(png_ptr, readbuf, length);
1813 png_ptr->num_trans = (png_uint_16)length;
1818 png_crc_finish(png_ptr, length);
1819 png_chunk_benign_error(png_ptr, "invalid with alpha channel");
1823 if (png_crc_finish(png_ptr, 0))
1825 png_ptr->num_trans = 0;
1829 /* TODO: this is a horrible side effect in the palette case because the
1830 * png_struct ends up with a pointer to the tRNS buffer owned by the
1831 * png_info. Fix this.
1833 png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
1834 &(png_ptr->trans_color));
1838 #ifdef PNG_READ_bKGD_SUPPORTED
1840 png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1842 unsigned int truelen;
1844 png_color_16 background;
1846 png_debug(1, "in png_handle_bKGD");
1848 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1849 png_chunk_error(png_ptr, "missing IHDR");
1851 else if ((png_ptr->mode & PNG_HAVE_IDAT) ||
1852 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
1853 !(png_ptr->mode & PNG_HAVE_PLTE)))
1855 png_crc_finish(png_ptr, length);
1856 png_chunk_benign_error(png_ptr, "out of place");
1860 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
1862 png_crc_finish(png_ptr, length);
1863 png_chunk_benign_error(png_ptr, "duplicate");
1867 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1870 else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
1876 if (length != truelen)
1878 png_crc_finish(png_ptr, length);
1879 png_chunk_benign_error(png_ptr, "invalid");
1883 png_crc_read(png_ptr, buf, truelen);
1885 if (png_crc_finish(png_ptr, 0))
1888 /* We convert the index value into RGB components so that we can allow
1889 * arbitrary RGB values for background when we have transparency, and
1890 * so it is easy to determine the RGB values of the background color
1891 * from the info_ptr struct.
1893 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1895 background.index = buf[0];
1897 if (info_ptr && info_ptr->num_palette)
1899 if (buf[0] >= info_ptr->num_palette)
1901 png_chunk_benign_error(png_ptr, "invalid index");
1905 background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
1906 background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
1907 background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
1911 background.red = background.green = background.blue = 0;
1913 background.gray = 0;
1916 else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
1918 background.index = 0;
1922 background.gray = png_get_uint_16(buf);
1927 background.index = 0;
1928 background.red = png_get_uint_16(buf);
1929 background.green = png_get_uint_16(buf + 2);
1930 background.blue = png_get_uint_16(buf + 4);
1931 background.gray = 0;
1934 png_set_bKGD(png_ptr, info_ptr, &background);
1938 #ifdef PNG_READ_hIST_SUPPORTED
1940 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1942 unsigned int num, i;
1943 png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
1945 png_debug(1, "in png_handle_hIST");
1947 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1948 png_chunk_error(png_ptr, "missing IHDR");
1950 else if ((png_ptr->mode & PNG_HAVE_IDAT) || !(png_ptr->mode & PNG_HAVE_PLTE))
1952 png_crc_finish(png_ptr, length);
1953 png_chunk_benign_error(png_ptr, "out of place");
1957 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
1959 png_crc_finish(png_ptr, length);
1960 png_chunk_benign_error(png_ptr, "duplicate");
1966 if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH)
1968 png_crc_finish(png_ptr, length);
1969 png_chunk_benign_error(png_ptr, "invalid");
1973 for (i = 0; i < num; i++)
1977 png_crc_read(png_ptr, buf, 2);
1978 readbuf[i] = png_get_uint_16(buf);
1981 if (png_crc_finish(png_ptr, 0))
1984 png_set_hIST(png_ptr, info_ptr, readbuf);
1988 #ifdef PNG_READ_pHYs_SUPPORTED
1990 png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
1993 png_uint_32 res_x, res_y;
1996 png_debug(1, "in png_handle_pHYs");
1998 if (!(png_ptr->mode & PNG_HAVE_IHDR))
1999 png_chunk_error(png_ptr, "missing IHDR");
2001 else if (png_ptr->mode & PNG_HAVE_IDAT)
2003 png_crc_finish(png_ptr, length);
2004 png_chunk_benign_error(png_ptr, "out of place");
2008 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
2010 png_crc_finish(png_ptr, length);
2011 png_chunk_benign_error(png_ptr, "duplicate");
2017 png_crc_finish(png_ptr, length);
2018 png_chunk_benign_error(png_ptr, "invalid");
2022 png_crc_read(png_ptr, buf, 9);
2024 if (png_crc_finish(png_ptr, 0))
2027 res_x = png_get_uint_32(buf);
2028 res_y = png_get_uint_32(buf + 4);
2030 png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
2034 #ifdef PNG_READ_oFFs_SUPPORTED
2036 png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2039 png_int_32 offset_x, offset_y;
2042 png_debug(1, "in png_handle_oFFs");
2044 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2045 png_chunk_error(png_ptr, "missing IHDR");
2047 else if (png_ptr->mode & PNG_HAVE_IDAT)
2049 png_crc_finish(png_ptr, length);
2050 png_chunk_benign_error(png_ptr, "out of place");
2054 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
2056 png_crc_finish(png_ptr, length);
2057 png_chunk_benign_error(png_ptr, "duplicate");
2063 png_crc_finish(png_ptr, length);
2064 png_chunk_benign_error(png_ptr, "invalid");
2068 png_crc_read(png_ptr, buf, 9);
2070 if (png_crc_finish(png_ptr, 0))
2073 offset_x = png_get_int_32(buf);
2074 offset_y = png_get_int_32(buf + 4);
2076 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
2080 #ifdef PNG_READ_pCAL_SUPPORTED
2081 /* Read the pCAL chunk (described in the PNG Extensions document) */
2083 png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2086 png_byte type, nparams;
2087 png_bytep buffer, buf, units, endptr;
2091 png_debug(1, "in png_handle_pCAL");
2093 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2094 png_chunk_error(png_ptr, "missing IHDR");
2096 else if (png_ptr->mode & PNG_HAVE_IDAT)
2098 png_crc_finish(png_ptr, length);
2099 png_chunk_benign_error(png_ptr, "out of place");
2103 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
2105 png_crc_finish(png_ptr, length);
2106 png_chunk_benign_error(png_ptr, "duplicate");
2110 png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
2113 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2117 png_crc_finish(png_ptr, length);
2118 png_chunk_benign_error(png_ptr, "out of memory");
2122 png_crc_read(png_ptr, buffer, length);
2124 if (png_crc_finish(png_ptr, 0))
2127 buffer[length] = 0; /* Null terminate the last string */
2129 png_debug(3, "Finding end of pCAL purpose string");
2130 for (buf = buffer; *buf; buf++)
2133 endptr = buffer + length;
2135 /* We need to have at least 12 bytes after the purpose string
2136 * in order to get the parameter information.
2138 if (endptr <= buf + 12)
2140 png_chunk_benign_error(png_ptr, "invalid");
2144 png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
2145 X0 = png_get_int_32((png_bytep)buf+1);
2146 X1 = png_get_int_32((png_bytep)buf+5);
2151 png_debug(3, "Checking pCAL equation type and number of parameters");
2152 /* Check that we have the right number of parameters for known
2155 if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
2156 (type == PNG_EQUATION_BASE_E && nparams != 3) ||
2157 (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
2158 (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
2160 png_chunk_benign_error(png_ptr, "invalid parameter count");
2164 else if (type >= PNG_EQUATION_LAST)
2166 png_chunk_benign_error(png_ptr, "unrecognized equation type");
2169 for (buf = units; *buf; buf++)
2170 /* Empty loop to move past the units string. */ ;
2172 png_debug(3, "Allocating pCAL parameters array");
2174 params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
2175 nparams * (sizeof (png_charp))));
2179 png_chunk_benign_error(png_ptr, "out of memory");
2183 /* Get pointers to the start of each parameter string. */
2184 for (i = 0; i < nparams; i++)
2186 buf++; /* Skip the null string terminator from previous parameter. */
2188 png_debug1(3, "Reading pCAL parameter %d", i);
2190 for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
2191 /* Empty loop to move past each parameter string */ ;
2193 /* Make sure we haven't run out of data yet */
2196 png_free(png_ptr, params);
2197 png_chunk_benign_error(png_ptr, "invalid data");
2202 png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
2203 (png_charp)units, params);
2205 png_free(png_ptr, params);
2209 #ifdef PNG_READ_sCAL_SUPPORTED
2210 /* Read the sCAL chunk */
2212 png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2218 png_debug(1, "in png_handle_sCAL");
2220 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2221 png_chunk_error(png_ptr, "missing IHDR");
2223 else if (png_ptr->mode & PNG_HAVE_IDAT)
2225 png_crc_finish(png_ptr, length);
2226 png_chunk_benign_error(png_ptr, "out of place");
2230 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
2232 png_crc_finish(png_ptr, length);
2233 png_chunk_benign_error(png_ptr, "duplicate");
2237 /* Need unit type, width, \0, height: minimum 4 bytes */
2238 else if (length < 4)
2240 png_crc_finish(png_ptr, length);
2241 png_chunk_benign_error(png_ptr, "invalid");
2245 png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
2248 buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
2252 png_chunk_benign_error(png_ptr, "out of memory");
2253 png_crc_finish(png_ptr, length);
2257 png_crc_read(png_ptr, buffer, length);
2258 buffer[length] = 0; /* Null terminate the last string */
2260 if (png_crc_finish(png_ptr, 0))
2263 /* Validate the unit. */
2264 if (buffer[0] != 1 && buffer[0] != 2)
2266 png_chunk_benign_error(png_ptr, "invalid unit");
2270 /* Validate the ASCII numbers, need two ASCII numbers separated by
2271 * a '\0' and they need to fit exactly in the chunk data.
2276 if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
2277 i >= length || buffer[i++] != 0)
2278 png_chunk_benign_error(png_ptr, "bad width format");
2280 else if (!PNG_FP_IS_POSITIVE(state))
2281 png_chunk_benign_error(png_ptr, "non-positive width");
2285 png_size_t heighti = i;
2288 if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
2290 png_chunk_benign_error(png_ptr, "bad height format");
2292 else if (!PNG_FP_IS_POSITIVE(state))
2293 png_chunk_benign_error(png_ptr, "non-positive height");
2296 /* This is the (only) success case. */
2297 png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
2298 (png_charp)buffer+1, (png_charp)buffer+heighti);
2303 #ifdef PNG_READ_tIME_SUPPORTED
2305 png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2310 png_debug(1, "in png_handle_tIME");
2312 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2313 png_chunk_error(png_ptr, "missing IHDR");
2315 else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
2317 png_crc_finish(png_ptr, length);
2318 png_chunk_benign_error(png_ptr, "duplicate");
2322 if (png_ptr->mode & PNG_HAVE_IDAT)
2323 png_ptr->mode |= PNG_AFTER_IDAT;
2327 png_crc_finish(png_ptr, length);
2328 png_chunk_benign_error(png_ptr, "invalid");
2332 png_crc_read(png_ptr, buf, 7);
2334 if (png_crc_finish(png_ptr, 0))
2337 mod_time.second = buf[6];
2338 mod_time.minute = buf[5];
2339 mod_time.hour = buf[4];
2340 mod_time.day = buf[3];
2341 mod_time.month = buf[2];
2342 mod_time.year = png_get_uint_16(buf);
2344 png_set_tIME(png_ptr, info_ptr, &mod_time);
2348 #ifdef PNG_READ_tEXt_SUPPORTED
2349 /* Note: this does not properly handle chunks that are > 64K under DOS */
2351 png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2357 png_uint_32 skip = 0;
2359 png_debug(1, "in png_handle_tEXt");
2361 #ifdef PNG_USER_LIMITS_SUPPORTED
2362 if (png_ptr->user_chunk_cache_max != 0)
2364 if (png_ptr->user_chunk_cache_max == 1)
2366 png_crc_finish(png_ptr, length);
2370 if (--png_ptr->user_chunk_cache_max == 1)
2372 png_crc_finish(png_ptr, length);
2373 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2379 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2380 png_chunk_error(png_ptr, "missing IHDR");
2382 if (png_ptr->mode & PNG_HAVE_IDAT)
2383 png_ptr->mode |= PNG_AFTER_IDAT;
2385 #ifdef PNG_MAX_MALLOC_64K
2386 if (length > 65535U)
2388 png_crc_finish(png_ptr, length);
2389 png_chunk_benign_error(png_ptr, "too large to fit in memory");
2394 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2398 png_chunk_benign_error(png_ptr, "out of memory");
2402 png_crc_read(png_ptr, buffer, length);
2404 if (png_crc_finish(png_ptr, skip))
2407 key = (png_charp)buffer;
2410 for (text = key; *text; text++)
2411 /* Empty loop to find end of key */ ;
2413 if (text != key + length)
2416 text_info.compression = PNG_TEXT_COMPRESSION_NONE;
2417 text_info.key = key;
2418 text_info.lang = NULL;
2419 text_info.lang_key = NULL;
2420 text_info.itxt_length = 0;
2421 text_info.text = text;
2422 text_info.text_length = strlen(text);
2424 if (png_set_text_2(png_ptr, info_ptr, &text_info, 1))
2425 png_warning(png_ptr, "Insufficient memory to process text chunk");
2429 #ifdef PNG_READ_zTXt_SUPPORTED
2430 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2432 png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2434 png_const_charp errmsg = NULL;
2436 png_uint_32 keyword_length;
2438 png_debug(1, "in png_handle_zTXt");
2440 #ifdef PNG_USER_LIMITS_SUPPORTED
2441 if (png_ptr->user_chunk_cache_max != 0)
2443 if (png_ptr->user_chunk_cache_max == 1)
2445 png_crc_finish(png_ptr, length);
2449 if (--png_ptr->user_chunk_cache_max == 1)
2451 png_crc_finish(png_ptr, length);
2452 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2458 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2459 png_chunk_error(png_ptr, "missing IHDR");
2461 if (png_ptr->mode & PNG_HAVE_IDAT)
2462 png_ptr->mode |= PNG_AFTER_IDAT;
2464 buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
2468 png_crc_finish(png_ptr, length);
2469 png_chunk_benign_error(png_ptr, "out of memory");
2473 png_crc_read(png_ptr, buffer, length);
2475 if (png_crc_finish(png_ptr, 0))
2478 /* TODO: also check that the keyword contents match the spec! */
2479 for (keyword_length = 0;
2480 keyword_length < length && buffer[keyword_length] != 0;
2482 /* Empty loop to find end of name */ ;
2484 if (keyword_length > 79 || keyword_length < 1)
2485 errmsg = "bad keyword";
2487 /* zTXt must have some LZ data after the keyword, although it may expand to
2488 * zero bytes; we need a '\0' at the end of the keyword, the compression type
2491 else if (keyword_length + 3 > length)
2492 errmsg = "truncated";
2494 else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
2495 errmsg = "unknown compression type";
2499 png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
2501 /* TODO: at present png_decompress_chunk imposes a single application
2502 * level memory limit, this should be split to different values for iCCP
2505 if (png_decompress_chunk(png_ptr, length, keyword_length+2,
2506 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2510 /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
2511 * for the extra compression type byte and the fact that it isn't
2512 * necessarily '\0' terminated.
2514 buffer = png_ptr->read_buffer;
2515 buffer[uncompressed_length+(keyword_length+2)] = 0;
2517 text.compression = PNG_TEXT_COMPRESSION_zTXt;
2518 text.key = (png_charp)buffer;
2519 text.text = (png_charp)(buffer + keyword_length+2);
2520 text.text_length = uncompressed_length;
2521 text.itxt_length = 0;
2523 text.lang_key = NULL;
2525 if (png_set_text_2(png_ptr, info_ptr, &text, 1))
2526 errmsg = "insufficient memory";
2530 errmsg = png_ptr->zstream.msg;
2534 png_chunk_benign_error(png_ptr, errmsg);
2538 #ifdef PNG_READ_iTXt_SUPPORTED
2539 /* Note: this does not correctly handle chunks that are > 64K under DOS */
2541 png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
2543 png_const_charp errmsg = NULL;
2545 png_uint_32 prefix_length;
2547 png_debug(1, "in png_handle_iTXt");
2549 #ifdef PNG_USER_LIMITS_SUPPORTED
2550 if (png_ptr->user_chunk_cache_max != 0)
2552 if (png_ptr->user_chunk_cache_max == 1)
2554 png_crc_finish(png_ptr, length);
2558 if (--png_ptr->user_chunk_cache_max == 1)
2560 png_crc_finish(png_ptr, length);
2561 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2567 if (!(png_ptr->mode & PNG_HAVE_IHDR))
2568 png_chunk_error(png_ptr, "missing IHDR");
2570 if (png_ptr->mode & PNG_HAVE_IDAT)
2571 png_ptr->mode |= PNG_AFTER_IDAT;
2573 buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
2577 png_crc_finish(png_ptr, length);
2578 png_chunk_benign_error(png_ptr, "out of memory");
2582 png_crc_read(png_ptr, buffer, length);
2584 if (png_crc_finish(png_ptr, 0))
2587 /* First the keyword. */
2588 for (prefix_length=0;
2589 prefix_length < length && buffer[prefix_length] != 0;
2593 /* Perform a basic check on the keyword length here. */
2594 if (prefix_length > 79 || prefix_length < 1)
2595 errmsg = "bad keyword";
2597 /* Expect keyword, compression flag, compression type, language, translated
2598 * keyword (both may be empty but are 0 terminated) then the text, which may
2601 else if (prefix_length + 5 > length)
2602 errmsg = "truncated";
2604 else if (buffer[prefix_length+1] == 0 ||
2605 (buffer[prefix_length+1] == 1 &&
2606 buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
2608 int compressed = buffer[prefix_length+1] != 0;
2609 png_uint_32 language_offset, translated_keyword_offset;
2610 png_alloc_size_t uncompressed_length = 0;
2612 /* Now the language tag */
2614 language_offset = prefix_length;
2616 for (; prefix_length < length && buffer[prefix_length] != 0;
2620 /* WARNING: the length may be invalid here, this is checked below. */
2621 translated_keyword_offset = ++prefix_length;
2623 for (; prefix_length < length && buffer[prefix_length] != 0;
2627 /* prefix_length should now be at the trailing '\0' of the translated
2628 * keyword, but it may already be over the end. None of this arithmetic
2629 * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
2630 * systems the available allocaton may overflow.
2634 if (!compressed && prefix_length <= length)
2635 uncompressed_length = length - prefix_length;
2637 else if (compressed && prefix_length < length)
2639 uncompressed_length = PNG_SIZE_MAX;
2641 /* TODO: at present png_decompress_chunk imposes a single application
2642 * level memory limit, this should be split to different values for
2643 * iCCP and text chunks.
2645 if (png_decompress_chunk(png_ptr, length, prefix_length,
2646 &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
2647 buffer = png_ptr->read_buffer;
2650 errmsg = png_ptr->zstream.msg;
2654 errmsg = "truncated";
2660 buffer[uncompressed_length+prefix_length] = 0;
2663 text.compression = PNG_ITXT_COMPRESSION_NONE;
2666 text.compression = PNG_ITXT_COMPRESSION_zTXt;
2668 text.key = (png_charp)buffer;
2669 text.lang = (png_charp)buffer + language_offset;
2670 text.lang_key = (png_charp)buffer + translated_keyword_offset;
2671 text.text = (png_charp)buffer + prefix_length;
2672 text.text_length = 0;
2673 text.itxt_length = uncompressed_length;
2675 if (png_set_text_2(png_ptr, info_ptr, &text, 1))
2676 errmsg = "insufficient memory";
2681 errmsg = "bad compression info";
2684 png_chunk_benign_error(png_ptr, errmsg);
2688 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2689 /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
2691 png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
2693 png_alloc_size_t limit = PNG_SIZE_MAX;
2695 if (png_ptr->unknown_chunk.data != NULL)
2697 png_free(png_ptr, png_ptr->unknown_chunk.data);
2698 png_ptr->unknown_chunk.data = NULL;
2701 # ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
2702 if (png_ptr->user_chunk_malloc_max > 0 &&
2703 png_ptr->user_chunk_malloc_max < limit)
2704 limit = png_ptr->user_chunk_malloc_max;
2706 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
2707 if (PNG_USER_CHUNK_MALLOC_MAX < limit)
2708 limit = PNG_USER_CHUNK_MALLOC_MAX;
2711 if (length <= limit)
2713 PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
2714 /* The following is safe because of the PNG_SIZE_MAX init above */
2715 png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
2716 /* 'mode' is a flag array, only the bottom four bits matter here */
2717 png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
2720 png_ptr->unknown_chunk.data = NULL;
2724 /* Do a 'warn' here - it is handled below. */
2725 png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
2726 png_malloc_warn(png_ptr, length));
2730 if (png_ptr->unknown_chunk.data == NULL && length > 0)
2732 /* This is benign because we clean up correctly */
2733 png_crc_finish(png_ptr, length);
2734 png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
2741 png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
2742 png_crc_finish(png_ptr, 0);
2746 #endif /* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2748 /* Handle an unknown, or known but disabled, chunk */
2750 png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
2751 png_uint_32 length, int keep)
2753 int handled = 0; /* the chunk was handled */
2755 png_debug(1, "in png_handle_unknown");
2757 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
2758 /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
2759 * the bug which meant that setting a non-default behavior for a specific
2760 * chunk would be ignored (the default was always used unless a user
2761 * callback was installed).
2763 * 'keep' is the value from the png_chunk_unknown_handling, the setting for
2764 * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
2765 * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
2766 * This is just an optimization to avoid multiple calls to the lookup
2769 # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
2770 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2771 keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
2775 /* One of the following methods will read the chunk or skip it (at least one
2776 * of these is always defined because this is the only way to switch on
2777 * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
2779 # ifdef PNG_READ_USER_CHUNKS_SUPPORTED
2780 /* The user callback takes precedence over the chunk keep value, but the
2781 * keep value is still required to validate a save of a critical chunk.
2783 if (png_ptr->read_user_chunk_fn != NULL)
2785 if (png_cache_unknown_chunk(png_ptr, length))
2787 /* Callback to user unknown chunk handler */
2788 int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
2789 &png_ptr->unknown_chunk);
2792 * negative: An error occured, png_chunk_error will be called.
2793 * zero: The chunk was not handled, the chunk will be discarded
2794 * unless png_set_keep_unknown_chunks has been used to set
2795 * a 'keep' behavior for this particular chunk, in which
2796 * case that will be used. A critical chunk will cause an
2797 * error at this point unless it is to be saved.
2798 * positive: The chunk was handled, libpng will ignore/discard it.
2801 png_chunk_error(png_ptr, "error in user chunk");
2805 /* If the keep value is 'default' or 'never' override it, but
2806 * still error out on critical chunks unless the keep value is
2807 * 'always' While this is weird it is the behavior in 1.4.12. A
2808 * possible improvement would be to obey the value set for the
2809 * chunk, but this would be an API change that would probably
2810 * damage some applications.
2812 * The png_app_warning below catches the case that matters, where
2813 * the application has neither set specific save for this chunk
2816 if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
2818 # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2819 if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
2820 png_app_warning(png_ptr,
2821 "forcing save of an unhandled chunk; please call png_set_keep_unknown_chunks");
2823 keep = PNG_HANDLE_CHUNK_IF_SAFE;
2827 else /* chunk was handled */
2830 /* Critical chunks can be safely discarded at this point. */
2831 keep = PNG_HANDLE_CHUNK_NEVER;
2836 keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
2840 /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
2841 # endif /* PNG_READ_USER_CHUNKS_SUPPORTED */
2843 # ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
2845 /* keep is currently just the per-chunk setting, if there was no
2846 * setting change it to the global default now (not that this may
2847 * still be AS_DEFAULT) then obtain the cache of the chunk if required,
2848 * if not simply skip the chunk.
2850 if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
2851 keep = png_ptr->unknown_default;
2853 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
2854 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
2855 PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name)))
2857 if (!png_cache_unknown_chunk(png_ptr, length))
2858 keep = PNG_HANDLE_CHUNK_NEVER;
2862 png_crc_finish(png_ptr, length);
2865 # ifndef PNG_READ_USER_CHUNKS_SUPPORTED
2866 # error no method to support READ_UNKNOWN_CHUNKS
2870 /* If here there is no read callback pointer set and no support is
2871 * compiled in to just save the unknown chunks, so simply skip this
2872 * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then
2873 * the app has erroneously asked for unknown chunk saving when there
2876 if (keep > PNG_HANDLE_CHUNK_NEVER)
2877 png_app_error(png_ptr, "no unknown chunk support available");
2879 png_crc_finish(png_ptr, length);
2883 # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2884 /* Now store the chunk in the chunk list if appropriate, and if the limits
2887 if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
2888 (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
2889 PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name)))
2891 # ifdef PNG_USER_LIMITS_SUPPORTED
2892 switch (png_ptr->user_chunk_cache_max)
2895 png_ptr->user_chunk_cache_max = 1;
2896 png_chunk_benign_error(png_ptr, "no space in chunk cache");
2899 /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
2900 * chunk being skipped, now there will be a hard error below.
2904 default: /* not at limit */
2905 --(png_ptr->user_chunk_cache_max);
2907 case 0: /* no limit */
2908 # endif /* PNG_USER_LIMITS_SUPPORTED */
2909 /* Here when the limit isn't reached or when limits are compiled
2910 * out; store the chunk.
2912 png_set_unknown_chunks(png_ptr, info_ptr,
2913 &png_ptr->unknown_chunk, 1);
2915 # ifdef PNG_USER_LIMITS_SUPPORTED
2920 # else /* no store support! */
2921 PNG_UNUSED(info_ptr)
2922 # error untested code (reading unknown chunks with no store support)
2925 /* Regardless of the error handling below the cached data (if any) can be
2926 * freed now. Notice that the data is not freed if there is a png_error, but
2927 * it will be freed by destroy_read_struct.
2929 if (png_ptr->unknown_chunk.data != NULL)
2930 png_free(png_ptr, png_ptr->unknown_chunk.data);
2931 png_ptr->unknown_chunk.data = NULL;
2933 #else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2934 /* There is no support to read an unknown chunk, so just skip it. */
2935 png_crc_finish(png_ptr, length);
2936 PNG_UNUSED(info_ptr)
2938 #endif /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
2940 /* Check for unhandled critical chunks */
2941 if (!handled && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
2942 png_chunk_error(png_ptr, "unhandled critical chunk");
2945 /* This function is called to verify that a chunk name is valid.
2946 * This function can't have the "critical chunk check" incorporated
2947 * into it, since in the future we will need to be able to call user
2948 * functions to handle unknown critical chunks after we check that
2949 * the chunk name itself is valid.
2952 /* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
2954 * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
2958 png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
2962 png_debug(1, "in png_check_chunk_name");
2964 for (i=1; i<=4; ++i)
2966 int c = chunk_name & 0xff;
2968 if (c < 65 || c > 122 || (c > 90 && c < 97))
2969 png_chunk_error(png_ptr, "invalid chunk type");
2975 /* Combines the row recently read in with the existing pixels in the row. This
2976 * routine takes care of alpha and transparency if requested. This routine also
2977 * handles the two methods of progressive display of interlaced images,
2978 * depending on the 'display' value; if 'display' is true then the whole row
2979 * (dp) is filled from the start by replicating the available pixels. If
2980 * 'display' is false only those pixels present in the pass are filled in.
2983 png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
2985 unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
2986 png_const_bytep sp = png_ptr->row_buf + 1;
2987 png_uint_32 row_width = png_ptr->width;
2988 unsigned int pass = png_ptr->pass;
2989 png_bytep end_ptr = 0;
2990 png_byte end_byte = 0;
2991 unsigned int end_mask;
2993 png_debug(1, "in png_combine_row");
2995 /* Added in 1.5.6: it should not be possible to enter this routine until at
2996 * least one row has been read from the PNG data and transformed.
2998 if (pixel_depth == 0)
2999 png_error(png_ptr, "internal row logic error");
3001 /* Added in 1.5.4: the pixel depth should match the information returned by
3002 * any call to png_read_update_info at this point. Do not continue if we got
3005 if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
3006 PNG_ROWBYTES(pixel_depth, row_width))
3007 png_error(png_ptr, "internal row size calculation error");
3009 /* Don't expect this to ever happen: */
3011 png_error(png_ptr, "internal row width error");
3013 /* Preserve the last byte in cases where only part of it will be overwritten,
3014 * the multiply below may overflow, we don't care because ANSI-C guarantees
3015 * we get the low bits.
3017 end_mask = (pixel_depth * row_width) & 7;
3020 /* end_ptr == NULL is a flag to say do nothing */
3021 end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
3022 end_byte = *end_ptr;
3023 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3024 if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
3025 end_mask = 0xff << end_mask;
3027 else /* big-endian byte */
3029 end_mask = 0xff >> end_mask;
3030 /* end_mask is now the bits to *keep* from the destination row */
3033 /* For non-interlaced images this reduces to a memcpy(). A memcpy()
3034 * will also happen if interlacing isn't supported or if the application
3035 * does not call png_set_interlace_handling(). In the latter cases the
3036 * caller just gets a sequence of the unexpanded rows from each interlace
3039 #ifdef PNG_READ_INTERLACING_SUPPORTED
3040 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
3041 pass < 6 && (display == 0 ||
3042 /* The following copies everything for 'display' on passes 0, 2 and 4. */
3043 (display == 1 && (pass & 1) != 0)))
3045 /* Narrow images may have no bits in a pass; the caller should handle
3046 * this, but this test is cheap:
3048 if (row_width <= PNG_PASS_START_COL(pass))
3051 if (pixel_depth < 8)
3053 /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
3054 * into 32 bits, then a single loop over the bytes using the four byte
3055 * values in the 32-bit mask can be used. For the 'display' option the
3056 * expanded mask may also not require any masking within a byte. To
3057 * make this work the PACKSWAP option must be taken into account - it
3058 * simply requires the pixels to be reversed in each byte.
3060 * The 'regular' case requires a mask for each of the first 6 passes,
3061 * the 'display' case does a copy for the even passes in the range
3062 * 0..6. This has already been handled in the test above.
3064 * The masks are arranged as four bytes with the first byte to use in
3065 * the lowest bits (little-endian) regardless of the order (PACKSWAP or
3066 * not) of the pixels in each byte.
3068 * NOTE: the whole of this logic depends on the caller of this function
3069 * only calling it on rows appropriate to the pass. This function only
3070 * understands the 'x' logic; the 'y' logic is handled by the caller.
3072 * The following defines allow generation of compile time constant bit
3073 * masks for each pixel depth and each possibility of swapped or not
3074 * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index,
3075 * is in the range 0..7; and the result is 1 if the pixel is to be
3076 * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B'
3077 * for the block method.
3079 * With some compilers a compile time expression of the general form:
3081 * (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
3083 * Produces warnings with values of 'shift' in the range 33 to 63
3084 * because the right hand side of the ?: expression is evaluated by
3085 * the compiler even though it isn't used. Microsoft Visual C (various
3086 * versions) and the Intel C compiler are known to do this. To avoid
3087 * this the following macros are used in 1.5.6. This is a temporary
3088 * solution to avoid destabilizing the code during the release process.
3090 # if PNG_USE_COMPILE_TIME_MASKS
3091 # define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
3092 # define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
3094 # define PNG_LSR(x,s) ((x)>>(s))
3095 # define PNG_LSL(x,s) ((x)<<(s))
3097 # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
3098 PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
3099 # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
3100 PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
3102 /* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is
3103 * little endian - the first pixel is at bit 0 - however the extra
3104 * parameter 's' can be set to cause the mask position to be swapped
3105 * within each byte, to match the PNG format. This is done by XOR of
3106 * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
3108 # define PIXEL_MASK(p,x,d,s) \
3109 (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
3111 /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
3113 # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3114 # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
3116 /* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp
3117 * cases the result needs replicating, for the 4-bpp case the above
3118 * generates a full 32 bits.
3120 # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
3122 # define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
3123 S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
3124 S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
3126 # define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
3127 B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
3128 B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
3130 #if PNG_USE_COMPILE_TIME_MASKS
3131 /* Utility macros to construct all the masks for a depth/swap
3132 * combination. The 's' parameter says whether the format is PNG
3133 * (big endian bytes) or not. Only the three odd-numbered passes are
3134 * required for the display/block algorithm.
3136 # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
3137 S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
3139 # define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }
3141 # define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
3143 /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
3146 static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
3148 /* Little-endian byte masks for PACKSWAP */
3149 { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
3150 /* Normal (big-endian byte) masks - PNG format */
3151 { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
3154 /* display_mask has only three entries for the odd passes, so index by
3157 static PNG_CONST png_uint_32 display_mask[2][3][3] =
3159 /* Little-endian byte masks for PACKSWAP */
3160 { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
3161 /* Normal (big-endian byte) masks - PNG format */
3162 { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
3165 # define MASK(pass,depth,display,png)\
3166 ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
3167 row_mask[png][DEPTH_INDEX(depth)][pass])
3169 #else /* !PNG_USE_COMPILE_TIME_MASKS */
3170 /* This is the runtime alternative: it seems unlikely that this will
3171 * ever be either smaller or faster than the compile time approach.
3173 # define MASK(pass,depth,display,png)\
3174 ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
3175 #endif /* !PNG_USE_COMPILE_TIME_MASKS */
3177 /* Use the appropriate mask to copy the required bits. In some cases
3178 * the byte mask will be 0 or 0xff, optimize these cases. row_width is
3179 * the number of pixels, but the code copies bytes, so it is necessary
3180 * to special case the end.
3182 png_uint_32 pixels_per_byte = 8 / pixel_depth;
3185 # ifdef PNG_READ_PACKSWAP_SUPPORTED
3186 if (png_ptr->transformations & PNG_PACKSWAP)
3187 mask = MASK(pass, pixel_depth, display, 0);
3191 mask = MASK(pass, pixel_depth, display, 1);
3197 /* It doesn't matter in the following if png_uint_32 has more than
3198 * 32 bits because the high bits always match those in m<<24; it is,
3199 * however, essential to use OR here, not +, because of this.
3202 mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
3205 if (m != 0) /* something to copy */
3208 *dp = (png_byte)((*dp & ~m) | (*sp & m));
3213 /* NOTE: this may overwrite the last byte with garbage if the image
3214 * is not an exact number of bytes wide; libpng has always done
3217 if (row_width <= pixels_per_byte)
3218 break; /* May need to restore part of the last byte */
3220 row_width -= pixels_per_byte;
3226 else /* pixel_depth >= 8 */
3228 unsigned int bytes_to_copy, bytes_to_jump;
3230 /* Validate the depth - it must be a multiple of 8 */
3231 if (pixel_depth & 7)
3232 png_error(png_ptr, "invalid user transform pixel depth");
3234 pixel_depth >>= 3; /* now in bytes */
3235 row_width *= pixel_depth;
3237 /* Regardless of pass number the Adam 7 interlace always results in a
3238 * fixed number of pixels to copy then to skip. There may be a
3239 * different number of pixels to skip at the start though.
3242 unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
3244 row_width -= offset;
3249 /* Work out the bytes to copy. */
3252 /* When doing the 'block' algorithm the pixel in the pass gets
3253 * replicated to adjacent pixels. This is why the even (0,2,4,6)
3254 * passes are skipped above - the entire expanded row is copied.
3256 bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
3258 /* But don't allow this number to exceed the actual row width. */
3259 if (bytes_to_copy > row_width)
3260 bytes_to_copy = row_width;
3263 else /* normal row; Adam7 only ever gives us one pixel to copy. */
3264 bytes_to_copy = pixel_depth;
3266 /* In Adam7 there is a constant offset between where the pixels go. */
3267 bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
3269 /* And simply copy these bytes. Some optimization is possible here,
3270 * depending on the value of 'bytes_to_copy'. Special case the low
3271 * byte counts, which we know to be frequent.
3273 * Notice that these cases all 'return' rather than 'break' - this
3274 * avoids an unnecessary test on whether to restore the last byte
3277 switch (bytes_to_copy)
3284 if (row_width <= bytes_to_jump)
3287 dp += bytes_to_jump;
3288 sp += bytes_to_jump;
3289 row_width -= bytes_to_jump;
3293 /* There is a possibility of a partial copy at the end here; this
3294 * slows the code down somewhat.
3298 dp[0] = sp[0], dp[1] = sp[1];
3300 if (row_width <= bytes_to_jump)
3303 sp += bytes_to_jump;
3304 dp += bytes_to_jump;
3305 row_width -= bytes_to_jump;
3307 while (row_width > 1);
3309 /* And there can only be one byte left at this point: */
3314 /* This can only be the RGB case, so each copy is exactly one
3315 * pixel and it is not necessary to check for a partial copy.
3319 dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
3321 if (row_width <= bytes_to_jump)
3324 sp += bytes_to_jump;
3325 dp += bytes_to_jump;
3326 row_width -= bytes_to_jump;
3330 #if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
3331 /* Check for double byte alignment and, if possible, use a
3332 * 16-bit copy. Don't attempt this for narrow images - ones that
3333 * are less than an interlace panel wide. Don't attempt it for
3334 * wide bytes_to_copy either - use the memcpy there.
3336 if (bytes_to_copy < 16 /*else use memcpy*/ &&
3337 png_isaligned(dp, png_uint_16) &&
3338 png_isaligned(sp, png_uint_16) &&
3339 bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
3340 bytes_to_jump % (sizeof (png_uint_16)) == 0)
3342 /* Everything is aligned for png_uint_16 copies, but try for
3343 * png_uint_32 first.
3345 if (png_isaligned(dp, png_uint_32) &&
3346 png_isaligned(sp, png_uint_32) &&
3347 bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
3348 bytes_to_jump % (sizeof (png_uint_32)) == 0)
3350 png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
3351 png_const_uint_32p sp32 = png_aligncastconst(
3352 png_const_uint_32p, sp);
3353 unsigned int skip = (bytes_to_jump-bytes_to_copy) /
3354 (sizeof (png_uint_32));
3358 size_t c = bytes_to_copy;
3362 c -= (sizeof (png_uint_32));
3366 if (row_width <= bytes_to_jump)
3371 row_width -= bytes_to_jump;
3373 while (bytes_to_copy <= row_width);
3375 /* Get to here when the row_width truncates the final copy.
3376 * There will be 1-3 bytes left to copy, so don't try the
3377 * 16-bit loop below.
3379 dp = (png_bytep)dp32;
3380 sp = (png_const_bytep)sp32;
3383 while (--row_width > 0);
3387 /* Else do it in 16-bit quantities, but only if the size is
3392 png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
3393 png_const_uint_16p sp16 = png_aligncastconst(
3394 png_const_uint_16p, sp);
3395 unsigned int skip = (bytes_to_jump-bytes_to_copy) /
3396 (sizeof (png_uint_16));
3400 size_t c = bytes_to_copy;
3404 c -= (sizeof (png_uint_16));
3408 if (row_width <= bytes_to_jump)
3413 row_width -= bytes_to_jump;
3415 while (bytes_to_copy <= row_width);
3417 /* End of row - 1 byte left, bytes_to_copy > row_width: */
3418 dp = (png_bytep)dp16;
3419 sp = (png_const_bytep)sp16;
3422 while (--row_width > 0);
3426 #endif /* PNG_ALIGN_ code */
3428 /* The true default - use a memcpy: */
3431 memcpy(dp, sp, bytes_to_copy);
3433 if (row_width <= bytes_to_jump)
3436 sp += bytes_to_jump;
3437 dp += bytes_to_jump;
3438 row_width -= bytes_to_jump;
3439 if (bytes_to_copy > row_width)
3440 bytes_to_copy = row_width;
3445 } /* pixel_depth >= 8 */
3447 /* Here if pixel_depth < 8 to check 'end_ptr' below. */
3452 /* If here then the switch above wasn't used so just memcpy the whole row
3453 * from the temporary row buffer (notice that this overwrites the end of the
3454 * destination row if it is a partial byte.)
3456 memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
3458 /* Restore the overwritten bits from the last byte if necessary. */
3459 if (end_ptr != NULL)
3460 *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
3463 #ifdef PNG_READ_INTERLACING_SUPPORTED
3465 png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
3466 png_uint_32 transformations /* Because these may affect the byte layout */)
3468 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
3469 /* Offset to next interlace block */
3470 static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
3472 png_debug(1, "in png_do_read_interlace");
3473 if (row != NULL && row_info != NULL)
3475 png_uint_32 final_width;
3477 final_width = row_info->width * png_pass_inc[pass];
3479 switch (row_info->pixel_depth)
3483 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
3484 png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
3486 int s_start, s_end, s_inc;
3487 int jstop = png_pass_inc[pass];
3492 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3493 if (transformations & PNG_PACKSWAP)
3495 sshift = (int)((row_info->width + 7) & 0x07);
3496 dshift = (int)((final_width + 7) & 0x07);
3505 sshift = 7 - (int)((row_info->width + 7) & 0x07);
3506 dshift = 7 - (int)((final_width + 7) & 0x07);
3512 for (i = 0; i < row_info->width; i++)
3514 v = (png_byte)((*sp >> sshift) & 0x01);
3515 for (j = 0; j < jstop; j++)
3517 unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
3519 *dp = (png_byte)(tmp & 0xff);
3521 if (dshift == s_end)
3531 if (sshift == s_end)
3545 png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
3546 png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
3548 int s_start, s_end, s_inc;
3549 int jstop = png_pass_inc[pass];
3552 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3553 if (transformations & PNG_PACKSWAP)
3555 sshift = (int)(((row_info->width + 3) & 0x03) << 1);
3556 dshift = (int)(((final_width + 3) & 0x03) << 1);
3565 sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
3566 dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
3572 for (i = 0; i < row_info->width; i++)
3577 v = (png_byte)((*sp >> sshift) & 0x03);
3578 for (j = 0; j < jstop; j++)
3580 unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
3582 *dp = (png_byte)(tmp & 0xff);
3584 if (dshift == s_end)
3594 if (sshift == s_end)
3608 png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
3609 png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
3611 int s_start, s_end, s_inc;
3613 int jstop = png_pass_inc[pass];
3615 #ifdef PNG_READ_PACKSWAP_SUPPORTED
3616 if (transformations & PNG_PACKSWAP)
3618 sshift = (int)(((row_info->width + 1) & 0x01) << 2);
3619 dshift = (int)(((final_width + 1) & 0x01) << 2);
3628 sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
3629 dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
3635 for (i = 0; i < row_info->width; i++)
3637 png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
3640 for (j = 0; j < jstop; j++)
3642 unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
3644 *dp = (png_byte)(tmp & 0xff);
3646 if (dshift == s_end)
3656 if (sshift == s_end)
3670 png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
3672 png_bytep sp = row + (png_size_t)(row_info->width - 1)
3675 png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
3677 int jstop = png_pass_inc[pass];
3680 for (i = 0; i < row_info->width; i++)
3685 memcpy(v, sp, pixel_bytes);
3687 for (j = 0; j < jstop; j++)
3689 memcpy(dp, v, pixel_bytes);
3699 row_info->width = final_width;
3700 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
3702 #ifndef PNG_READ_PACKSWAP_SUPPORTED
3703 PNG_UNUSED(transformations) /* Silence compiler warning */
3706 #endif /* PNG_READ_INTERLACING_SUPPORTED */
3709 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
3710 png_const_bytep prev_row)
3713 png_size_t istop = row_info->rowbytes;
3714 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3715 png_bytep rp = row + bpp;
3717 PNG_UNUSED(prev_row)
3719 for (i = bpp; i < istop; i++)
3721 *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
3727 png_read_filter_row_up(png_row_infop row_info, png_bytep row,
3728 png_const_bytep prev_row)
3731 png_size_t istop = row_info->rowbytes;
3733 png_const_bytep pp = prev_row;
3735 for (i = 0; i < istop; i++)
3737 *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
3743 png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
3744 png_const_bytep prev_row)
3748 png_const_bytep pp = prev_row;
3749 unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
3750 png_size_t istop = row_info->rowbytes - bpp;
3752 for (i = 0; i < bpp; i++)
3754 *rp = (png_byte)(((int)(*rp) +
3755 ((int)(*pp++) / 2 )) & 0xff);
3760 for (i = 0; i < istop; i++)
3762 *rp = (png_byte)(((int)(*rp) +
3763 (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
3770 png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
3771 png_const_bytep prev_row)
3773 png_bytep rp_end = row + row_info->rowbytes;
3776 /* First pixel/byte */
3779 *row++ = (png_byte)a;
3782 while (row < rp_end)
3784 int b, pa, pb, pc, p;
3786 a &= 0xff; /* From previous iteration or start */
3797 pa = p < 0 ? -p : p;
3798 pb = pc < 0 ? -pc : pc;
3799 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3802 /* Find the best predictor, the least of pa, pb, pc favoring the earlier
3803 * ones in the case of a tie.
3805 if (pb < pa) pa = pb, a = b;
3808 /* Calculate the current pixel in a, and move the previous row pixel to c
3809 * for the next time round the loop
3813 *row++ = (png_byte)a;
3818 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
3819 png_const_bytep prev_row)
3821 int bpp = (row_info->pixel_depth + 7) >> 3;
3822 png_bytep rp_end = row + bpp;
3824 /* Process the first pixel in the row completely (this is the same as 'up'
3825 * because there is only one candidate predictor for the first row).
3827 while (row < rp_end)
3829 int a = *row + *prev_row++;
3830 *row++ = (png_byte)a;
3834 rp_end += row_info->rowbytes - bpp;
3836 while (row < rp_end)
3838 int a, b, c, pa, pb, pc, p;
3840 c = *(prev_row - bpp);
3852 pa = p < 0 ? -p : p;
3853 pb = pc < 0 ? -pc : pc;
3854 pc = (p + pc) < 0 ? -(p + pc) : p + pc;
3857 if (pb < pa) pa = pb, a = b;
3862 *row++ = (png_byte)a;
3867 png_init_filter_functions(png_structrp pp)
3868 /* This function is called once for every PNG image to set the
3869 * implementations required to reverse the filtering of PNG rows. Reversing
3870 * the filter is the first transformation performed on the row data. It is
3871 * performed in place, therefore an implementation can be selected based on
3872 * the image pixel format. If the implementation depends on image width then
3873 * take care to ensure that it works corretly if the image is interlaced -
3874 * interlacing causes the actual row width to vary.
3877 unsigned int bpp = (pp->pixel_depth + 7) >> 3;
3879 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
3880 pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
3881 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
3883 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
3884 png_read_filter_row_paeth_1byte_pixel;
3886 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
3887 png_read_filter_row_paeth_multibyte_pixel;
3889 #ifdef PNG_FILTER_OPTIMIZATIONS
3890 /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
3891 * call to install hardware optimizations for the above functions; simply
3892 * replace whatever elements of the pp->read_filter[] array with a hardware
3893 * specific (or, for that matter, generic) optimization.
3895 * To see an example of this examine what configure.ac does when
3896 * --enable-arm-neon is specified on the command line.
3898 PNG_FILTER_OPTIMIZATIONS(pp, bpp);
3903 png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
3904 png_const_bytep prev_row, int filter)
3906 /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
3907 * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
3908 * implementations. See png_init_filter_functions above.
3910 if (pp->read_filter[0] == NULL)
3911 png_init_filter_functions(pp);
3912 if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
3913 pp->read_filter[filter-1](row_info, row, prev_row);
3916 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
3918 png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
3919 png_alloc_size_t avail_out)
3921 /* Loop reading IDATs and decompressing the result into output[avail_out] */
3922 png_ptr->zstream.next_out = output;
3923 png_ptr->zstream.avail_out = 0; /* safety: set below */
3931 png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
3933 if (png_ptr->zstream.avail_in == 0)
3938 while (png_ptr->idat_size == 0)
3940 png_crc_finish(png_ptr, 0);
3942 png_ptr->idat_size = png_read_chunk_header(png_ptr);
3943 /* This is an error even in the 'check' case because the code just
3944 * consumed a non-IDAT header.
3946 if (png_ptr->chunk_name != png_IDAT)
3947 png_error(png_ptr, "Not enough image data");
3950 avail_in = png_ptr->IDAT_read_size;
3952 if (avail_in > png_ptr->idat_size)
3953 avail_in = (uInt)png_ptr->idat_size;
3955 /* A PNG with a gradually increasing IDAT size will defeat this attempt
3956 * to minimize memory usage by causing lots of re-allocs, but
3957 * realistically doing IDAT_read_size re-allocs is not likely to be a
3960 buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
3962 png_crc_read(png_ptr, buffer, avail_in);
3963 png_ptr->idat_size -= avail_in;
3965 png_ptr->zstream.next_in = buffer;
3966 png_ptr->zstream.avail_in = avail_in;
3969 /* And set up the output side. */
3970 if (output != NULL) /* standard read */
3972 uInt out = ZLIB_IO_MAX;
3974 if (out > avail_out)
3975 out = (uInt)avail_out;
3978 png_ptr->zstream.avail_out = out;
3981 else /* check for end */
3983 png_ptr->zstream.next_out = tmpbuf;
3984 png_ptr->zstream.avail_out = (sizeof tmpbuf);
3987 /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
3988 * process. If the LZ stream is truncated the sequential reader will
3989 * terminally damage the stream, above, by reading the chunk header of the
3990 * following chunk (it then exits with png_error).
3992 * TODO: deal more elegantly with truncated IDAT lists.
3994 ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
3996 /* Take the unconsumed output back (so, in the 'check' case this just
3999 avail_out += png_ptr->zstream.avail_out;
4000 png_ptr->zstream.avail_out = 0;
4002 if (ret == Z_STREAM_END)
4004 /* Do this for safety; we won't read any more into this row. */
4005 png_ptr->zstream.next_out = NULL;
4007 png_ptr->mode |= PNG_AFTER_IDAT;
4008 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4010 if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
4011 png_chunk_benign_error(png_ptr, "Extra compressed data");
4017 png_zstream_error(png_ptr, ret);
4020 png_chunk_error(png_ptr, png_ptr->zstream.msg);
4024 png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
4028 } while (avail_out > 0);
4032 /* The stream ended before the image; this is the same as too few IDATs so
4033 * should be handled the same way.
4036 png_error(png_ptr, "Not enough image data");
4039 png_chunk_benign_error(png_ptr, "Too much image data");
4044 png_read_finish_IDAT(png_structrp png_ptr)
4046 /* We don't need any more data and the stream should have ended, however the
4047 * LZ end code may actually not have been processed. In this case we must
4048 * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
4049 * may still remain to be consumed.
4051 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
4053 /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
4054 * the compressed stream, but the stream may be damaged too, so even after
4055 * this call we may need to terminate the zstream ownership.
4057 png_read_IDAT_data(png_ptr, NULL, 0);
4058 png_ptr->zstream.next_out = NULL; /* safety */
4060 /* Now clear everything out for safety; the following may not have been
4063 if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
4065 png_ptr->mode |= PNG_AFTER_IDAT;
4066 png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
4070 /* If the zstream has not been released do it now *and* terminate the reading
4071 * of the final IDAT chunk.
4073 if (png_ptr->zowner == png_IDAT)
4075 /* Always do this; the pointers otherwise point into the read buffer. */
4076 png_ptr->zstream.next_in = NULL;
4077 png_ptr->zstream.avail_in = 0;
4079 /* Now we no longer own the zstream. */
4080 png_ptr->zowner = 0;
4082 /* The slightly weird semantics of the sequential IDAT reading is that we
4083 * are always in or at the end of an IDAT chunk, so we always need to do a
4084 * crc_finish here. If idat_size is non-zero we also need to read the
4085 * spurious bytes at the end of the chunk now.
4087 (void)png_crc_finish(png_ptr, png_ptr->idat_size);
4092 png_read_finish_row(png_structrp png_ptr)
4094 #ifdef PNG_READ_INTERLACING_SUPPORTED
4095 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4097 /* Start of interlace block */
4098 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4100 /* Offset to next interlace block */
4101 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4103 /* Start of interlace block in the y direction */
4104 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4106 /* Offset to next interlace block in the y direction */
4107 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4108 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4110 png_debug(1, "in png_read_finish_row");
4111 png_ptr->row_number++;
4112 if (png_ptr->row_number < png_ptr->num_rows)
4115 #ifdef PNG_READ_INTERLACING_SUPPORTED
4116 if (png_ptr->interlaced)
4118 png_ptr->row_number = 0;
4120 /* TO DO: don't do this if prev_row isn't needed (requires
4121 * read-ahead of the next row's filter byte.
4123 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4129 if (png_ptr->pass >= 7)
4132 png_ptr->iwidth = (png_ptr->width +
4133 png_pass_inc[png_ptr->pass] - 1 -
4134 png_pass_start[png_ptr->pass]) /
4135 png_pass_inc[png_ptr->pass];
4137 if (!(png_ptr->transformations & PNG_INTERLACE))
4139 png_ptr->num_rows = (png_ptr->height +
4140 png_pass_yinc[png_ptr->pass] - 1 -
4141 png_pass_ystart[png_ptr->pass]) /
4142 png_pass_yinc[png_ptr->pass];
4145 else /* if (png_ptr->transformations & PNG_INTERLACE) */
4146 break; /* libpng deinterlacing sees every row */
4148 } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
4150 if (png_ptr->pass < 7)
4153 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4155 /* Here after at the end of the last row of the last pass. */
4156 png_read_finish_IDAT(png_ptr);
4158 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
4161 png_read_start_row(png_structrp png_ptr)
4163 #ifdef PNG_READ_INTERLACING_SUPPORTED
4164 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
4166 /* Start of interlace block */
4167 static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
4169 /* Offset to next interlace block */
4170 static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
4172 /* Start of interlace block in the y direction */
4173 static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
4175 /* Offset to next interlace block in the y direction */
4176 static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
4179 int max_pixel_depth;
4180 png_size_t row_bytes;
4182 png_debug(1, "in png_read_start_row");
4184 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
4185 png_init_read_transformations(png_ptr);
4187 #ifdef PNG_READ_INTERLACING_SUPPORTED
4188 if (png_ptr->interlaced)
4190 if (!(png_ptr->transformations & PNG_INTERLACE))
4191 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
4192 png_pass_ystart[0]) / png_pass_yinc[0];
4195 png_ptr->num_rows = png_ptr->height;
4197 png_ptr->iwidth = (png_ptr->width +
4198 png_pass_inc[png_ptr->pass] - 1 -
4199 png_pass_start[png_ptr->pass]) /
4200 png_pass_inc[png_ptr->pass];
4204 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4206 png_ptr->num_rows = png_ptr->height;
4207 png_ptr->iwidth = png_ptr->width;
4210 max_pixel_depth = png_ptr->pixel_depth;
4212 /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of
4213 * calculations to calculate the final pixel depth, then
4214 * png_do_read_transforms actually does the transforms. This means that the
4215 * code which effectively calculates this value is actually repeated in three
4216 * separate places. They must all match. Innocent changes to the order of
4217 * transformations can and will break libpng in a way that causes memory
4222 #ifdef PNG_READ_PACK_SUPPORTED
4223 if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
4224 max_pixel_depth = 8;
4227 #ifdef PNG_READ_EXPAND_SUPPORTED
4228 if (png_ptr->transformations & PNG_EXPAND)
4230 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4232 if (png_ptr->num_trans)
4233 max_pixel_depth = 32;
4236 max_pixel_depth = 24;
4239 else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4241 if (max_pixel_depth < 8)
4242 max_pixel_depth = 8;
4244 if (png_ptr->num_trans)
4245 max_pixel_depth *= 2;
4248 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
4250 if (png_ptr->num_trans)
4252 max_pixel_depth *= 4;
4253 max_pixel_depth /= 3;
4259 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4260 if (png_ptr->transformations & PNG_EXPAND_16)
4262 # ifdef PNG_READ_EXPAND_SUPPORTED
4263 /* In fact it is an error if it isn't supported, but checking is
4266 if (png_ptr->transformations & PNG_EXPAND)
4268 if (png_ptr->bit_depth < 16)
4269 max_pixel_depth *= 2;
4273 png_ptr->transformations &= ~PNG_EXPAND_16;
4277 #ifdef PNG_READ_FILLER_SUPPORTED
4278 if (png_ptr->transformations & (PNG_FILLER))
4280 if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
4282 if (max_pixel_depth <= 8)
4283 max_pixel_depth = 16;
4286 max_pixel_depth = 32;
4289 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
4290 png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
4292 if (max_pixel_depth <= 32)
4293 max_pixel_depth = 32;
4296 max_pixel_depth = 64;
4301 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4302 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
4305 #ifdef PNG_READ_EXPAND_SUPPORTED
4306 (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
4308 #ifdef PNG_READ_FILLER_SUPPORTED
4309 (png_ptr->transformations & (PNG_FILLER)) ||
4311 png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4313 if (max_pixel_depth <= 16)
4314 max_pixel_depth = 32;
4317 max_pixel_depth = 64;
4322 if (max_pixel_depth <= 8)
4324 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4325 max_pixel_depth = 32;
4328 max_pixel_depth = 24;
4331 else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4332 max_pixel_depth = 64;
4335 max_pixel_depth = 48;
4340 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
4341 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
4342 if (png_ptr->transformations & PNG_USER_TRANSFORM)
4344 int user_pixel_depth = png_ptr->user_transform_depth *
4345 png_ptr->user_transform_channels;
4347 if (user_pixel_depth > max_pixel_depth)
4348 max_pixel_depth = user_pixel_depth;
4352 /* This value is stored in png_struct and double checked in the row read
4355 png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
4356 png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
4358 /* Align the width on the next larger 8 pixels. Mainly used
4361 row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
4362 /* Calculate the maximum bytes needed, adding a byte and a pixel
4365 row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
4366 1 + ((max_pixel_depth + 7) >> 3);
4368 #ifdef PNG_MAX_MALLOC_64K
4369 if (row_bytes > (png_uint_32)65536L)
4370 png_error(png_ptr, "This image requires a row greater than 64KB");
4373 if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
4375 png_free(png_ptr, png_ptr->big_row_buf);
4376 png_free(png_ptr, png_ptr->big_prev_row);
4378 if (png_ptr->interlaced)
4379 png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
4383 png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4385 png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
4387 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
4388 /* Use 16-byte aligned memory for row_buf with at least 16 bytes
4389 * of padding before and after row_buf; treat prev_row similarly.
4390 * NOTE: the alignment is to the start of the pixels, one beyond the start
4391 * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this
4392 * was incorrect; the filter byte was aligned, which had the exact
4393 * opposite effect of that intended.
4396 png_bytep temp = png_ptr->big_row_buf + 32;
4397 int extra = (int)((temp - (png_bytep)0) & 0x0f);
4398 png_ptr->row_buf = temp - extra - 1/*filter byte*/;
4400 temp = png_ptr->big_prev_row + 32;
4401 extra = (int)((temp - (png_bytep)0) & 0x0f);
4402 png_ptr->prev_row = temp - extra - 1/*filter byte*/;
4406 /* Use 31 bytes of padding before and 17 bytes after row_buf. */
4407 png_ptr->row_buf = png_ptr->big_row_buf + 31;
4408 png_ptr->prev_row = png_ptr->big_prev_row + 31;
4410 png_ptr->old_big_row_buf_size = row_bytes + 48;
4413 #ifdef PNG_MAX_MALLOC_64K
4414 if (png_ptr->rowbytes > 65535)
4415 png_error(png_ptr, "This image requires a row greater than 64KB");
4418 if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
4419 png_error(png_ptr, "Row has too many bytes to allocate in memory");
4421 memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
4423 png_debug1(3, "width = %u,", png_ptr->width);
4424 png_debug1(3, "height = %u,", png_ptr->height);
4425 png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
4426 png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
4427 png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
4428 png_debug1(3, "irowbytes = %lu",
4429 (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
4431 /* The sequential reader needs a buffer for IDAT, but the progressive reader
4432 * does not, so free the read buffer now regardless; the sequential reader
4433 * reallocates it on demand.
4435 if (png_ptr->read_buffer)
4437 png_bytep buffer = png_ptr->read_buffer;
4439 png_ptr->read_buffer_size = 0;
4440 png_ptr->read_buffer = NULL;
4441 png_free(png_ptr, buffer);
4444 /* Finally claim the zstream for the inflate of the IDAT data, use the bits
4445 * value from the stream (note that this will result in a fatal error if the
4446 * IDAT stream has a bogus deflate header window_bits value, but this should
4447 * not be happening any longer!)
4449 if (png_inflate_claim(png_ptr, png_IDAT, 0) != Z_OK)
4450 png_error(png_ptr, png_ptr->zstream.msg);
4452 png_ptr->flags |= PNG_FLAG_ROW_INIT;
4454 #endif /* PNG_READ_SUPPORTED */