png.c@ 61853

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libpng 1.2.54 unmodified
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1
2	/* png.c - location for general purpose libpng functions
3	*
4	* Last changed in libpng 1.2.54 [November 12, 2015]
5	* Copyright (c) 1998-2015 Glenn Randers-Pehrson
6	* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7	* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8	*
9	* This code is released under the libpng license.
10	* For conditions of distribution and use, see the disclaimer
11	* and license in png.h
12	*/
13
14	#define PNG_INTERNAL
15	#define PNG_NO_EXTERN
16	#define PNG_NO_PEDANTIC_WARNINGS
17	#include "png.h"
18
19	/* Generate a compiler error if there is an old png.h in the search path. */
20	typedef version_1_2_54 Your_png_h_is_not_version_1_2_54;
21
22	/* Version information for C files. This had better match the version
23	* string defined in png.h.
24	*/
25
26	#ifdef PNG_USE_GLOBAL_ARRAYS
27	/* png_libpng_ver was changed to a function in version 1.0.5c */
28	PNG_CONST char png_libpng_ver[18] = PNG_LIBPNG_VER_STRING;
29
30	#ifdef PNG_READ_SUPPORTED
31
32	/* png_sig was changed to a function in version 1.0.5c */
33	/* Place to hold the signature string for a PNG file. */
34	PNG_CONST png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
35	#endif /* PNG_READ_SUPPORTED */
36
37	/* Invoke global declarations for constant strings for known chunk types */
38	PNG_IHDR;
39	PNG_IDAT;
40	PNG_IEND;
41	PNG_PLTE;
42	PNG_bKGD;
43	PNG_cHRM;
44	PNG_gAMA;
45	PNG_hIST;
46	PNG_iCCP;
47	PNG_iTXt;
48	PNG_oFFs;
49	PNG_pCAL;
50	PNG_sCAL;
51	PNG_pHYs;
52	PNG_sBIT;
53	PNG_sPLT;
54	PNG_sRGB;
55	PNG_tEXt;
56	PNG_tIME;
57	PNG_tRNS;
58	PNG_zTXt;
59
60	#ifdef PNG_READ_SUPPORTED
61	/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
62
63	/* Start of interlace block */
64	PNG_CONST int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
65
66	/* Offset to next interlace block */
67	PNG_CONST int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
68
69	/* Start of interlace block in the y direction */
70	PNG_CONST int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
71
72	/* Offset to next interlace block in the y direction */
73	PNG_CONST int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
74
75	/* Height of interlace block. This is not currently used - if you need
76	* it, uncomment it here and in png.h
77	PNG_CONST int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
78	*/
79
80	/* Mask to determine which pixels are valid in a pass */
81	PNG_CONST int FARDATA png_pass_mask[] =
82	{0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
83
84	/* Mask to determine which pixels to overwrite while displaying */
85	PNG_CONST int FARDATA png_pass_dsp_mask[]
86	= {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
87
88	#endif /* PNG_READ_SUPPORTED */
89	#endif /* PNG_USE_GLOBAL_ARRAYS */
90
91	/* Tells libpng that we have already handled the first "num_bytes" bytes
92	* of the PNG file signature. If the PNG data is embedded into another
93	* stream we can set num_bytes = 8 so that libpng will not attempt to read
94	* or write any of the magic bytes before it starts on the IHDR.
95	*/
96
97	#ifdef PNG_READ_SUPPORTED
98	void PNGAPI
99	png_set_sig_bytes(png_structp png_ptr, int num_bytes)
100	{
101	png_debug(1, "in png_set_sig_bytes");
102
103	if (png_ptr == NULL)
104	return;
105
106	if (num_bytes > 8)
107	png_error(png_ptr, "Too many bytes for PNG signature.");
108
109	png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
110	}
111
112	/* Checks whether the supplied bytes match the PNG signature. We allow
113	* checking less than the full 8-byte signature so that those apps that
114	* already read the first few bytes of a file to determine the file type
115	* can simply check the remaining bytes for extra assurance. Returns
116	* an integer less than, equal to, or greater than zero if sig is found,
117	* respectively, to be less than, to match, or be greater than the correct
118	* PNG signature (this is the same behaviour as strcmp, memcmp, etc).
119	*/
120	int PNGAPI
121	png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)
122	{
123	png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
124	if (num_to_check > 8)
125	num_to_check = 8;
126	else if (num_to_check < 1)
127	return (-1);
128
129	if (start > 7)
130	return (-1);
131
132	if (start + num_to_check > 8)
133	num_to_check = 8 - start;
134
135	return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
136	}
137
138	#if defined(PNG_1_0_X) \|\| defined(PNG_1_2_X)
139	/* (Obsolete) function to check signature bytes. It does not allow one
140	* to check a partial signature. This function might be removed in the
141	* future - use png_sig_cmp(). Returns true (nonzero) if the file is PNG.
142	*/
143	int PNGAPI
144	png_check_sig(png_bytep sig, int num)
145	{
146	return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));
147	}
148	#endif
149	#endif /* PNG_READ_SUPPORTED */
150
151	#if defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED)
152	/* Function to allocate memory for zlib and clear it to 0. */
153	#ifdef PNG_1_0_X
154	voidpf PNGAPI
155	#else
156	voidpf /* PRIVATE */
157	#endif
158	png_zalloc(voidpf png_ptr, uInt items, uInt size)
159	{
160	png_voidp ptr;
161	png_structp p;
162	png_uint_32 save_flags;
163	png_uint_32 num_bytes;
164
165	if (png_ptr == NULL)
166	return (NULL);
167
168	p=(png_structp)png_ptr;
169	save_flags=p->flags;
170
171	if (items > PNG_UINT_32_MAX/size)
172	{
173	png_warning (p, "Potential overflow in png_zalloc()");
174	return (NULL);
175	}
176	num_bytes = (png_uint_32)items * size;
177
178	p->flags\|=PNG_FLAG_MALLOC_NULL_MEM_OK;
179	ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
180	p->flags=save_flags;
181
182	#if defined(PNG_1_0_X) && !defined(PNG_NO_ZALLOC_ZERO)
183	if (ptr == NULL)
184	return ((voidpf)ptr);
185
186	if (num_bytes > (png_uint_32)0x8000L)
187	{
188	png_memset(ptr, 0, (png_size_t)0x8000L);
189	png_memset((png_bytep)ptr + (png_size_t)0x8000L, 0,
190	(png_size_t)(num_bytes - (png_uint_32)0x8000L));
191	}
192	else
193	{
194	png_memset(ptr, 0, (png_size_t)num_bytes);
195	}
196	#endif
197	return ((voidpf)ptr);
198	}
199
200	/* Function to free memory for zlib */
201	#ifdef PNG_1_0_X
202	void PNGAPI
203	#else
204	void /* PRIVATE */
205	#endif
206	png_zfree(voidpf png_ptr, voidpf ptr)
207	{
208	png_free((png_structp)png_ptr, (png_voidp)ptr);
209	}
210
211	/* Reset the CRC variable to 32 bits of 1's. Care must be taken
212	* in case CRC is > 32 bits to leave the top bits 0.
213	*/
214	void /* PRIVATE */
215	png_reset_crc(png_structp png_ptr)
216	{
217	png_ptr->crc = crc32(0, Z_NULL, 0);
218	}
219
220	/* Calculate the CRC over a section of data. We can only pass as
221	* much data to this routine as the largest single buffer size. We
222	* also check that this data will actually be used before going to the
223	* trouble of calculating it.
224	*/
225	void /* PRIVATE */
226	png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)
227	{
228	int need_crc = 1;
229
230	if (png_ptr->chunk_name[0] & 0x20) /* ancillary */
231	{
232	if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
233	(PNG_FLAG_CRC_ANCILLARY_USE \| PNG_FLAG_CRC_ANCILLARY_NOWARN))
234	need_crc = 0;
235	}
236	else /* critical */
237	{
238	if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
239	need_crc = 0;
240	}
241
242	if (need_crc)
243	png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length);
244	}
245
246	/* Allocate the memory for an info_struct for the application. We don't
247	* really need the png_ptr, but it could potentially be useful in the
248	* future. This should be used in favour of malloc(png_sizeof(png_info))
249	* and png_info_init() so that applications that want to use a shared
250	* libpng don't have to be recompiled if png_info changes size.
251	*/
252	png_infop PNGAPI
253	png_create_info_struct(png_structp png_ptr)
254	{
255	png_infop info_ptr;
256
257	png_debug(1, "in png_create_info_struct");
258
259	if (png_ptr == NULL)
260	return (NULL);
261
262	#ifdef PNG_USER_MEM_SUPPORTED
263	info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
264	png_ptr->malloc_fn, png_ptr->mem_ptr);
265	#else
266	info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
267	#endif
268	if (info_ptr != NULL)
269	png_info_init_3(&info_ptr, png_sizeof(png_info));
270
271	return (info_ptr);
272	}
273
274	/* This function frees the memory associated with a single info struct.
275	* Normally, one would use either png_destroy_read_struct() or
276	* png_destroy_write_struct() to free an info struct, but this may be
277	* useful for some applications.
278	*/
279	void PNGAPI
280	png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
281	{
282	png_infop info_ptr = NULL;
283
284	png_debug(1, "in png_destroy_info_struct");
285
286	if (png_ptr == NULL)
287	return;
288
289	if (info_ptr_ptr != NULL)
290	info_ptr = *info_ptr_ptr;
291
292	if (info_ptr != NULL)
293	{
294	png_info_destroy(png_ptr, info_ptr);
295
296	#ifdef PNG_USER_MEM_SUPPORTED
297	png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,
298	png_ptr->mem_ptr);
299	#else
300	png_destroy_struct((png_voidp)info_ptr);
301	#endif
302	*info_ptr_ptr = NULL;
303	}
304	}
305
306	/* Initialize the info structure. This is now an internal function (0.89)
307	* and applications using it are urged to use png_create_info_struct()
308	* instead.
309	*/
310	#if defined(PNG_1_0_X) \|\| defined(PNG_1_2_X)
311	#undef png_info_init
312	void PNGAPI
313	png_info_init(png_infop info_ptr)
314	{
315	/* We only come here via pre-1.0.12-compiled applications */
316	png_info_init_3(&info_ptr, 0);
317	}
318	#endif
319
320	void PNGAPI
321	png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
322	{
323	png_infop info_ptr = *ptr_ptr;
324
325	png_debug(1, "in png_info_init_3");
326
327	if (info_ptr == NULL)
328	return;
329
330	if (png_sizeof(png_info) > png_info_struct_size)
331	{
332	png_destroy_struct(info_ptr);
333	info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
334	*ptr_ptr = info_ptr;
335	if (info_ptr == NULL)
336	return;
337	}
338
339	/* Set everything to 0 */
340	png_memset(info_ptr, 0, png_sizeof(png_info));
341	}
342
343	#ifdef PNG_FREE_ME_SUPPORTED
344	void PNGAPI
345	png_data_freer(png_structp png_ptr, png_infop info_ptr,
346	int freer, png_uint_32 mask)
347	{
348	png_debug(1, "in png_data_freer");
349
350	if (png_ptr == NULL \|\| info_ptr == NULL)
351	return;
352
353	if (freer == PNG_DESTROY_WILL_FREE_DATA)
354	info_ptr->free_me \|= mask;
355	else if (freer == PNG_USER_WILL_FREE_DATA)
356	info_ptr->free_me &= ~mask;
357	else
358	png_warning(png_ptr,
359	"Unknown freer parameter in png_data_freer.");
360	}
361	#endif
362
363	void PNGAPI
364	png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
365	int num)
366	{
367	png_debug(1, "in png_free_data");
368
369	if (png_ptr == NULL \|\| info_ptr == NULL)
370	return;
371
372	#ifdef PNG_TEXT_SUPPORTED
373	/* Free text item num or (if num == -1) all text items */
374	#ifdef PNG_FREE_ME_SUPPORTED
375	if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
376	#else
377	if (mask & PNG_FREE_TEXT)
378	#endif
379	{
380	if (num != -1)
381	{
382	if (info_ptr->text && info_ptr->text[num].key)
383	{
384	png_free(png_ptr, info_ptr->text[num].key);
385	info_ptr->text[num].key = NULL;
386	}
387	}
388	else
389	{
390	int i;
391	for (i = 0; i < info_ptr->num_text; i++)
392	png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
393	png_free(png_ptr, info_ptr->text);
394	info_ptr->text = NULL;
395	info_ptr->num_text=0;
396	}
397	}
398	#endif
399
400	#ifdef PNG_tRNS_SUPPORTED
401	/* Free any tRNS entry */
402	#ifdef PNG_FREE_ME_SUPPORTED
403	if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
404	#else
405	if ((mask & PNG_FREE_TRNS) && (png_ptr->flags & PNG_FLAG_FREE_TRNS))
406	#endif
407	{
408	png_free(png_ptr, info_ptr->trans);
409	info_ptr->trans = NULL;
410	info_ptr->valid &= ~PNG_INFO_tRNS;
411	#ifndef PNG_FREE_ME_SUPPORTED
412	png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;
413	#endif
414	}
415	#endif
416
417	#ifdef PNG_sCAL_SUPPORTED
418	/* Free any sCAL entry */
419	#ifdef PNG_FREE_ME_SUPPORTED
420	if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
421	#else
422	if (mask & PNG_FREE_SCAL)
423	#endif
424	{
425	#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
426	png_free(png_ptr, info_ptr->scal_s_width);
427	png_free(png_ptr, info_ptr->scal_s_height);
428	info_ptr->scal_s_width = NULL;
429	info_ptr->scal_s_height = NULL;
430	#endif
431	info_ptr->valid &= ~PNG_INFO_sCAL;
432	}
433	#endif
434
435	#ifdef PNG_pCAL_SUPPORTED
436	/* Free any pCAL entry */
437	#ifdef PNG_FREE_ME_SUPPORTED
438	if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
439	#else
440	if (mask & PNG_FREE_PCAL)
441	#endif
442	{
443	png_free(png_ptr, info_ptr->pcal_purpose);
444	png_free(png_ptr, info_ptr->pcal_units);
445	info_ptr->pcal_purpose = NULL;
446	info_ptr->pcal_units = NULL;
447	if (info_ptr->pcal_params != NULL)
448	{
449	int i;
450	for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
451	{
452	png_free(png_ptr, info_ptr->pcal_params[i]);
453	info_ptr->pcal_params[i] = NULL;
454	}
455	png_free(png_ptr, info_ptr->pcal_params);
456	info_ptr->pcal_params = NULL;
457	}
458	info_ptr->valid &= ~PNG_INFO_pCAL;
459	}
460	#endif
461
462	#ifdef PNG_iCCP_SUPPORTED
463	/* Free any iCCP entry */
464	#ifdef PNG_FREE_ME_SUPPORTED
465	if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
466	#else
467	if (mask & PNG_FREE_ICCP)
468	#endif
469	{
470	png_free(png_ptr, info_ptr->iccp_name);
471	png_free(png_ptr, info_ptr->iccp_profile);
472	info_ptr->iccp_name = NULL;
473	info_ptr->iccp_profile = NULL;
474	info_ptr->valid &= ~PNG_INFO_iCCP;
475	}
476	#endif
477
478	#ifdef PNG_sPLT_SUPPORTED
479	/* Free a given sPLT entry, or (if num == -1) all sPLT entries */
480	#ifdef PNG_FREE_ME_SUPPORTED
481	if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
482	#else
483	if (mask & PNG_FREE_SPLT)
484	#endif
485	{
486	if (num != -1)
487	{
488	if (info_ptr->splt_palettes)
489	{
490	png_free(png_ptr, info_ptr->splt_palettes[num].name);
491	png_free(png_ptr, info_ptr->splt_palettes[num].entries);
492	info_ptr->splt_palettes[num].name = NULL;
493	info_ptr->splt_palettes[num].entries = NULL;
494	}
495	}
496	else
497	{
498	if (info_ptr->splt_palettes_num)
499	{
500	int i;
501	for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
502	png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);
503
504	png_free(png_ptr, info_ptr->splt_palettes);
505	info_ptr->splt_palettes = NULL;
506	info_ptr->splt_palettes_num = 0;
507	}
508	info_ptr->valid &= ~PNG_INFO_sPLT;
509	}
510	}
511	#endif
512
513	#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
514	if (png_ptr->unknown_chunk.data)
515	{
516	png_free(png_ptr, png_ptr->unknown_chunk.data);
517	png_ptr->unknown_chunk.data = NULL;
518	}
519
520	#ifdef PNG_FREE_ME_SUPPORTED
521	if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
522	#else
523	if (mask & PNG_FREE_UNKN)
524	#endif
525	{
526	if (num != -1)
527	{
528	if (info_ptr->unknown_chunks)
529	{
530	png_free(png_ptr, info_ptr->unknown_chunks[num].data);
531	info_ptr->unknown_chunks[num].data = NULL;
532	}
533	}
534	else
535	{
536	int i;
537
538	if (info_ptr->unknown_chunks_num)
539	{
540	for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)
541	png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);
542
543	png_free(png_ptr, info_ptr->unknown_chunks);
544	info_ptr->unknown_chunks = NULL;
545	info_ptr->unknown_chunks_num = 0;
546	}
547	}
548	}
549	#endif
550
551	#ifdef PNG_hIST_SUPPORTED
552	/* Free any hIST entry */
553	#ifdef PNG_FREE_ME_SUPPORTED
554	if ((mask & PNG_FREE_HIST) & info_ptr->free_me)
555	#else
556	if ((mask & PNG_FREE_HIST) && (png_ptr->flags & PNG_FLAG_FREE_HIST))
557	#endif
558	{
559	png_free(png_ptr, info_ptr->hist);
560	info_ptr->hist = NULL;
561	info_ptr->valid &= ~PNG_INFO_hIST;
562	#ifndef PNG_FREE_ME_SUPPORTED
563	png_ptr->flags &= ~PNG_FLAG_FREE_HIST;
564	#endif
565	}
566	#endif
567
568	/* Free any PLTE entry that was internally allocated */
569	#ifdef PNG_FREE_ME_SUPPORTED
570	if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
571	#else
572	if ((mask & PNG_FREE_PLTE) && (png_ptr->flags & PNG_FLAG_FREE_PLTE))
573	#endif
574	{
575	png_zfree(png_ptr, info_ptr->palette);
576	info_ptr->palette = NULL;
577	info_ptr->valid &= ~PNG_INFO_PLTE;
578	#ifndef PNG_FREE_ME_SUPPORTED
579	png_ptr->flags &= ~PNG_FLAG_FREE_PLTE;
580	#endif
581	info_ptr->num_palette = 0;
582	}
583
584	#ifdef PNG_INFO_IMAGE_SUPPORTED
585	/* Free any image bits attached to the info structure */
586	#ifdef PNG_FREE_ME_SUPPORTED
587	if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
588	#else
589	if (mask & PNG_FREE_ROWS)
590	#endif
591	{
592	if (info_ptr->row_pointers)
593	{
594	int row;
595	for (row = 0; row < (int)info_ptr->height; row++)
596	{
597	png_free(png_ptr, info_ptr->row_pointers[row]);
598	info_ptr->row_pointers[row] = NULL;
599	}
600	png_free(png_ptr, info_ptr->row_pointers);
601	info_ptr->row_pointers = NULL;
602	}
603	info_ptr->valid &= ~PNG_INFO_IDAT;
604	}
605	#endif
606
607	#ifdef PNG_FREE_ME_SUPPORTED
608	if (num == -1)
609	info_ptr->free_me &= ~mask;
610	else
611	info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);
612	#endif
613	}
614
615	/* This is an internal routine to free any memory that the info struct is
616	* pointing to before re-using it or freeing the struct itself. Recall
617	* that png_free() checks for NULL pointers for us.
618	*/
619	void /* PRIVATE */
620	png_info_destroy(png_structp png_ptr, png_infop info_ptr)
621	{
622	png_debug(1, "in png_info_destroy");
623
624	png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
625
626	#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
627	if (png_ptr->num_chunk_list)
628	{
629	png_free(png_ptr, png_ptr->chunk_list);
630	png_ptr->chunk_list = NULL;
631	png_ptr->num_chunk_list = 0;
632	}
633	#endif
634
635	png_info_init_3(&info_ptr, png_sizeof(png_info));
636	}
637	#endif /* defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED) */
638
639	/* This function returns a pointer to the io_ptr associated with the user
640	* functions. The application should free any memory associated with this
641	* pointer before png_write_destroy() or png_read_destroy() are called.
642	*/
643	png_voidp PNGAPI
644	png_get_io_ptr(png_structp png_ptr)
645	{
646	if (png_ptr == NULL)
647	return (NULL);
648	return (png_ptr->io_ptr);
649	}
650
651	#if defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED)
652	#ifdef PNG_STDIO_SUPPORTED
653	/* Initialize the default input/output functions for the PNG file. If you
654	* use your own read or write routines, you can call either png_set_read_fn()
655	* or png_set_write_fn() instead of png_init_io(). If you have defined
656	* PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't
657	* necessarily available.
658	*/
659	void PNGAPI
660	png_init_io(png_structp png_ptr, png_FILE_p fp)
661	{
662	png_debug(1, "in png_init_io");
663
664	if (png_ptr == NULL)
665	return;
666
667	png_ptr->io_ptr = (png_voidp)fp;
668	}
669	#endif
670
671	#ifdef PNG_TIME_RFC1123_SUPPORTED
672	/* Convert the supplied time into an RFC 1123 string suitable for use in
673	* a "Creation Time" or other text-based time string.
674	*/
675	png_charp PNGAPI
676	png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
677	{
678	static PNG_CONST char short_months[12][4] =
679	{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
680	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
681
682	if (png_ptr == NULL)
683	return (NULL);
684
685	if (png_ptr->time_buffer == NULL)
686	{
687	png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
688	png_sizeof(char)));
689	}
690
691	#ifdef _WIN32_WCE
692	{
693	wchar_t time_buf[29];
694	wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"),
695	ptime->day % 32, short_months[(ptime->month - 1U) % 12],
696	ptime->year, ptime->hour % 24, ptime->minute % 60,
697	ptime->second % 61);
698	WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer,
699	29, NULL, NULL);
700	}
701	#else
702	#ifdef USE_FAR_KEYWORD
703	{
704	char near_time_buf[29];
705	png_snprintf6(near_time_buf, 29, "%d %s %d %02d:%02d:%02d +0000",
706	ptime->day % 32, short_months[(ptime->month - 1U) % 12],
707	ptime->year, ptime->hour % 24, ptime->minute % 60,
708	ptime->second % 61);
709	png_memcpy(png_ptr->time_buffer, near_time_buf,
710	29*png_sizeof(char));
711	}
712	#else
713	png_snprintf6(png_ptr->time_buffer, 29, "%d %s %d %02d:%02d:%02d +0000",
714	ptime->day % 32, short_months[(ptime->month - 1U) % 12],
715	ptime->year, ptime->hour % 24, ptime->minute % 60,
716	ptime->second % 61);
717	#endif
718	#endif /* _WIN32_WCE */
719	return ((png_charp)png_ptr->time_buffer);
720	}
721	#endif /* PNG_TIME_RFC1123_SUPPORTED */
722
723	#endif /* defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED) */
724
725	png_charp PNGAPI
726	png_get_copyright(png_structp png_ptr)
727	{
728	PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
729	#ifdef PNG_STRING_COPYRIGHT
730	return PNG_STRING_COPYRIGHT
731	#else
732	#ifdef __STDC__
733	return ((png_charp) PNG_STRING_NEWLINE \
734	"libpng version 1.2.54 - November 12, 2015" PNG_STRING_NEWLINE \
735	"Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
736	"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
737	"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
738	PNG_STRING_NEWLINE);
739	#else
740	return ((png_charp) "libpng version 1.2.54 - November 12, 2015\
741	Copyright (c) 1998-2015 Glenn Randers-Pehrson\
742	Copyright (c) 1996-1997 Andreas Dilger\
743	Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.");
744	#endif
745	#endif
746	}
747
748	/* The following return the library version as a short string in the
749	* format 1.0.0 through 99.99.99zz. To get the version of *.h files
750	* used with your application, print out PNG_LIBPNG_VER_STRING, which
751	* is defined in png.h.
752	* Note: now there is no difference between png_get_libpng_ver() and
753	* png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
754	* it is guaranteed that png.c uses the correct version of png.h.
755	*/
756	png_charp PNGAPI
757	png_get_libpng_ver(png_structp png_ptr)
758	{
759	/* Version of .c files used when building libpng /
760	PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
761	return ((png_charp) PNG_LIBPNG_VER_STRING);
762	}
763
764	png_charp PNGAPI
765	png_get_header_ver(png_structp png_ptr)
766	{
767	/* Version of .h files used when building libpng /
768	PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
769	return ((png_charp) PNG_LIBPNG_VER_STRING);
770	}
771
772	png_charp PNGAPI
773	png_get_header_version(png_structp png_ptr)
774	{
775	/* Returns longer string containing both version and date */
776	PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
777	#ifdef __STDC__
778	return ((png_charp) PNG_HEADER_VERSION_STRING
779	#ifndef PNG_READ_SUPPORTED
780	" (NO READ SUPPORT)"
781	#endif
782	PNG_STRING_NEWLINE);
783	#else
784	return ((png_charp) PNG_HEADER_VERSION_STRING);
785	#endif
786	}
787
788	#if defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED)
789	#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
790	int PNGAPI
791	png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
792	{
793	/* Check chunk_name and return "keep" value if it's on the list, else 0 */
794	int i;
795	png_bytep p;
796	if (png_ptr == NULL \|\| chunk_name == NULL \|\| png_ptr->num_chunk_list<=0)
797	return 0;
798	p = png_ptr->chunk_list + png_ptr->num_chunk_list*5 - 5;
799	for (i = png_ptr->num_chunk_list; i; i--, p -= 5)
800	if (!png_memcmp(chunk_name, p, 4))
801	return ((int)*(p + 4));
802	return 0;
803	}
804	#endif
805
806	/* This function, added to libpng-1.0.6g, is untested. */
807	int PNGAPI
808	png_reset_zstream(png_structp png_ptr)
809	{
810	if (png_ptr == NULL)
811	return Z_STREAM_ERROR;
812	return (inflateReset(&png_ptr->zstream));
813	}
814	#endif /* defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED) */
815
816	/* This function was added to libpng-1.0.7 */
817	png_uint_32 PNGAPI
818	png_access_version_number(void)
819	{
820	/* Version of .c files used when building libpng /
821	return((png_uint_32) PNG_LIBPNG_VER);
822	}
823
824
825	#if defined(PNG_READ_SUPPORTED) && defined(PNG_ASSEMBLER_CODE_SUPPORTED)
826	#ifndef PNG_1_0_X
827	/* This function was added to libpng 1.2.0 */
828	int PNGAPI
829	png_mmx_support(void)
830	{
831	/* Obsolete, to be removed from libpng-1.4.0 */
832	return -1;
833	}
834	#endif /* PNG_1_0_X */
835	#endif /* PNG_READ_SUPPORTED && PNG_ASSEMBLER_CODE_SUPPORTED */
836
837	#if defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED)
838	#ifdef PNG_SIZE_T
839	/* Added at libpng version 1.2.6 */
840	PNG_EXTERN png_size_t PNGAPI png_convert_size PNGARG((size_t size));
841	png_size_t PNGAPI
842	png_convert_size(size_t size)
843	{
844	if (size > (png_size_t)-1)
845	PNG_ABORT(); /* We haven't got access to png_ptr, so no png_error() */
846	return ((png_size_t)size);
847	}
848	#endif /* PNG_SIZE_T */
849
850	/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
851	#ifdef PNG_cHRM_SUPPORTED
852	#ifdef PNG_CHECK_cHRM_SUPPORTED
853
854	/*
855	* Multiply two 32-bit numbers, V1 and V2, using 32-bit
856	* arithmetic, to produce a 64 bit result in the HI/LO words.
857	*
858	* A B
859	* x C D
860	* ------
861	* AD \|\| BD
862	* AC \|\| CB \|\| 0
863	*
864	* where A and B are the high and low 16-bit words of V1,
865	* C and D are the 16-bit words of V2, AD is the product of
866	* A and D, and X \|\| Y is (X << 16) + Y.
867	*/
868
869	void /* PRIVATE */
870	png_64bit_product (long v1, long v2, unsigned long *hi_product,
871	unsigned long *lo_product)
872	{
873	int a, b, c, d;
874	long lo, hi, x, y;
875
876	a = (v1 >> 16) & 0xffff;
877	b = v1 & 0xffff;
878	c = (v2 >> 16) & 0xffff;
879	d = v2 & 0xffff;
880
881	lo = b * d; /* BD */
882	x = a * d + c * b; /* AD + CB */
883	y = ((lo >> 16) & 0xffff) + x;
884
885	lo = (lo & 0xffff) \| ((y & 0xffff) << 16);
886	hi = (y >> 16) & 0xffff;
887
888	hi += a * c; /* AC */
889
890	*hi_product = (unsigned long)hi;
891	*lo_product = (unsigned long)lo;
892	}
893
894	int /* PRIVATE */
895	png_check_cHRM_fixed(png_structp png_ptr,
896	png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
897	png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
898	png_fixed_point blue_x, png_fixed_point blue_y)
899	{
900	int ret = 1;
901	unsigned long xy_hi,xy_lo,yx_hi,yx_lo;
902
903	png_debug(1, "in function png_check_cHRM_fixed");
904
905	if (png_ptr == NULL)
906	return 0;
907
908	if (white_x < 0 \|\| white_y <= 0 \|\|
909	red_x < 0 \|\| red_y < 0 \|\|
910	green_x < 0 \|\| green_y < 0 \|\|
911	blue_x < 0 \|\| blue_y < 0)
912	{
913	png_warning(png_ptr,
914	"Ignoring attempt to set negative chromaticity value");
915	ret = 0;
916	}
917	if (white_x > (png_fixed_point) PNG_UINT_31_MAX \|\|
918	white_y > (png_fixed_point) PNG_UINT_31_MAX \|\|
919	red_x > (png_fixed_point) PNG_UINT_31_MAX \|\|
920	red_y > (png_fixed_point) PNG_UINT_31_MAX \|\|
921	green_x > (png_fixed_point) PNG_UINT_31_MAX \|\|
922	green_y > (png_fixed_point) PNG_UINT_31_MAX \|\|
923	blue_x > (png_fixed_point) PNG_UINT_31_MAX \|\|
924	blue_y > (png_fixed_point) PNG_UINT_31_MAX )
925	{
926	png_warning(png_ptr,
927	"Ignoring attempt to set chromaticity value exceeding 21474.83");
928	ret = 0;
929	}
930	if (white_x > 100000L - white_y)
931	{
932	png_warning(png_ptr, "Invalid cHRM white point");
933	ret = 0;
934	}
935	if (red_x > 100000L - red_y)
936	{
937	png_warning(png_ptr, "Invalid cHRM red point");
938	ret = 0;
939	}
940	if (green_x > 100000L - green_y)
941	{
942	png_warning(png_ptr, "Invalid cHRM green point");
943	ret = 0;
944	}
945	if (blue_x > 100000L - blue_y)
946	{
947	png_warning(png_ptr, "Invalid cHRM blue point");
948	ret = 0;
949	}
950
951	png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo);
952	png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo);
953
954	if (xy_hi == yx_hi && xy_lo == yx_lo)
955	{
956	png_warning(png_ptr,
957	"Ignoring attempt to set cHRM RGB triangle with zero area");
958	ret = 0;
959	}
960
961	return ret;
962	}
963	#endif /* PNG_CHECK_cHRM_SUPPORTED */
964	#endif /* PNG_cHRM_SUPPORTED */
965
966	void /* PRIVATE */
967	png_check_IHDR(png_structp png_ptr,
968	png_uint_32 width, png_uint_32 height, int bit_depth,
969	int color_type, int interlace_type, int compression_type,
970	int filter_type)
971	{
972	int error = 0;
973
974	/* Check for width and height valid values */
975	if (width == 0)
976	{
977	png_warning(png_ptr, "Image width is zero in IHDR");
978	error = 1;
979	}
980
981	if (height == 0)
982	{
983	png_warning(png_ptr, "Image height is zero in IHDR");
984	error = 1;
985	}
986
987	#ifdef PNG_SET_USER_LIMITS_SUPPORTED
988	if (width > png_ptr->user_width_max \|\| width > PNG_USER_WIDTH_MAX)
989	#else
990	if (width > PNG_USER_WIDTH_MAX)
991	#endif
992	{
993	png_warning(png_ptr, "Image width exceeds user limit in IHDR");
994	error = 1;
995	}
996
997	#ifdef PNG_SET_USER_LIMITS_SUPPORTED
998	if (height > png_ptr->user_height_max \|\| height > PNG_USER_HEIGHT_MAX)
999	#else
1000	if (height > PNG_USER_HEIGHT_MAX)
1001	#endif
1002	{
1003	png_warning(png_ptr, "Image height exceeds user limit in IHDR");
1004	error = 1;
1005	}
1006
1007	if (width > PNG_UINT_31_MAX)
1008	{
1009	png_warning(png_ptr, "Invalid image width in IHDR");
1010	error = 1;
1011	}
1012
1013	if ( height > PNG_UINT_31_MAX)
1014	{
1015	png_warning(png_ptr, "Invalid image height in IHDR");
1016	error = 1;
1017	}
1018
1019	/* Check other values */
1020	if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
1021	bit_depth != 8 && bit_depth != 16)
1022	{
1023	png_warning(png_ptr, "Invalid bit depth in IHDR");
1024	error = 1;
1025	}
1026
1027	if (color_type < 0 \|\| color_type == 1 \|\|
1028	color_type == 5 \|\| color_type > 6)
1029	{
1030	png_warning(png_ptr, "Invalid color type in IHDR");
1031	error = 1;
1032	}
1033
1034	if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) \|\|
1035	((color_type == PNG_COLOR_TYPE_RGB \|\|
1036	color_type == PNG_COLOR_TYPE_GRAY_ALPHA \|\|
1037	color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
1038	{
1039	png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
1040	error = 1;
1041	}
1042
1043	if (interlace_type >= PNG_INTERLACE_LAST)
1044	{
1045	png_warning(png_ptr, "Unknown interlace method in IHDR");
1046	error = 1;
1047	}
1048
1049	if (compression_type != PNG_COMPRESSION_TYPE_BASE)
1050	{
1051	png_warning(png_ptr, "Unknown compression method in IHDR");
1052	error = 1;
1053	}
1054
1055	#ifdef PNG_MNG_FEATURES_SUPPORTED
1056	/* Accept filter_method 64 (intrapixel differencing) only if
1057	* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
1058	* 2. Libpng did not read a PNG signature (this filter_method is only
1059	* used in PNG datastreams that are embedded in MNG datastreams) and
1060	* 3. The application called png_permit_mng_features with a mask that
1061	* included PNG_FLAG_MNG_FILTER_64 and
1062	* 4. The filter_method is 64 and
1063	* 5. The color_type is RGB or RGBA
1064	*/
1065	if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) &&
1066	png_ptr->mng_features_permitted)
1067	png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
1068
1069	if (filter_type != PNG_FILTER_TYPE_BASE)
1070	{
1071	if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
1072	(filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
1073	((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
1074	(color_type == PNG_COLOR_TYPE_RGB \|\|
1075	color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
1076	{
1077	png_warning(png_ptr, "Unknown filter method in IHDR");
1078	error = 1;
1079	}
1080
1081	if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE)
1082	{
1083	png_warning(png_ptr, "Invalid filter method in IHDR");
1084	error = 1;
1085	}
1086	}
1087
1088	#else
1089	if (filter_type != PNG_FILTER_TYPE_BASE)
1090	{
1091	png_warning(png_ptr, "Unknown filter method in IHDR");
1092	error = 1;
1093	}
1094	#endif
1095
1096	if (error == 1)
1097	png_error(png_ptr, "Invalid IHDR data");
1098	}
1099	#endif /* defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED) */

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