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1
2 /* png.c - location for general purpose libpng functions
3 *
4 * libpng version 1.0.3 - January 14, 1999
5 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
6 * Copyright (c) 1996, 1997 Andreas Dilger
7 * Copyright (c) 1998, 1999 Glenn Randers-Pehrson
8 *
9 */
10
11 #define PNG_INTERNAL
12 #define PNG_NO_EXTERN
13 #include "png.h"
14
15 /* Version information for C files. This had better match the version
16 * string defined in png.h.
17 */
18
19 char png_libpng_ver[12] = "1.0.3";
20
21 /* Place to hold the signature string for a PNG file. */
22 png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
23
24 /* Constant strings for known chunk types. If you need to add a chunk,
25 * add a string holding the name here. If you want to make the code
26 * portable to EBCDIC machines, use ASCII numbers, not characters.
27 */
28 png_byte FARDATA png_IHDR[5] = { 73, 72, 68, 82, '\0'};
29 png_byte FARDATA png_IDAT[5] = { 73, 68, 65, 84, '\0'};
30 png_byte FARDATA png_IEND[5] = { 73, 69, 78, 68, '\0'};
31 png_byte FARDATA png_PLTE[5] = { 80, 76, 84, 69, '\0'};
32 png_byte FARDATA png_bKGD[5] = { 98, 75, 71, 68, '\0'};
33 png_byte FARDATA png_cHRM[5] = { 99, 72, 82, 77, '\0'};
34 png_byte FARDATA png_gAMA[5] = {103, 65, 77, 65, '\0'};
35 png_byte FARDATA png_hIST[5] = {104, 73, 83, 84, '\0'};
36 png_byte FARDATA png_oFFs[5] = {111, 70, 70, 115, '\0'};
37 png_byte FARDATA png_pCAL[5] = {112, 67, 65, 76, '\0'};
38 png_byte FARDATA png_pHYs[5] = {112, 72, 89, 115, '\0'};
39 png_byte FARDATA png_sBIT[5] = {115, 66, 73, 84, '\0'};
40 png_byte FARDATA png_sRGB[5] = {115, 82, 71, 66, '\0'};
41 png_byte FARDATA png_tEXt[5] = {116, 69, 88, 116, '\0'};
42 png_byte FARDATA png_tIME[5] = {116, 73, 77, 69, '\0'};
43 png_byte FARDATA png_tRNS[5] = {116, 82, 78, 83, '\0'};
44 png_byte FARDATA png_zTXt[5] = {122, 84, 88, 116, '\0'};
45
46 /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
47
48 /* start of interlace block */
49 int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
50
51 /* offset to next interlace block */
52 int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
53
54 /* start of interlace block in the y direction */
55 int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
56
57 /* offset to next interlace block in the y direction */
58 int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
59
60 /* Width of interlace block. This is not currently used - if you need
61 * it, uncomment it here and in png.h
62 int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1};
63 */
64
65 /* Height of interlace block. This is not currently used - if you need
66 * it, uncomment it here and in png.h
67 int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
68 */
69
70 /* Mask to determine which pixels are valid in a pass */
71 int FARDATA png_pass_mask[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
72
73 /* Mask to determine which pixels to overwrite while displaying */
74 int FARDATA png_pass_dsp_mask[] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
75
76
77 /* Tells libpng that we have already handled the first "num_bytes" bytes
78 * of the PNG file signature. If the PNG data is embedded into another
79 * stream we can set num_bytes = 8 so that libpng will not attempt to read
80 * or write any of the magic bytes before it starts on the IHDR.
81 */
82 void
83 png_set_sig_bytes(png_structp png_ptr, int num_bytes)
84 {
85 png_debug(1, "in png_set_sig_bytes\n");
86 if (num_bytes > 8)
87 png_error(png_ptr, "Too many bytes for PNG signature.");
88
89 png_ptr->sig_bytes = num_bytes < 0 ? 0 : num_bytes;
90 }
91
92 /* Checks whether the supplied bytes match the PNG signature. We allow
93 * checking less than the full 8-byte signature so that those apps that
94 * already read the first few bytes of a file to determine the file type
95 * can simply check the remaining bytes for extra assurance. Returns
96 * an integer less than, equal to, or greater than zero if sig is found,
97 * respectively, to be less than, to match, or be greater than the correct
98 * PNG signature (this is the same behaviour as strcmp, memcmp, etc).
99 */
100 int
101 png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)
102 {
103 if (num_to_check > 8)
104 num_to_check = 8;
105 else if (num_to_check < 1)
106 return (0);
107
108 if (start > 7)
109 return (0);
110
111 if (start + num_to_check > 8)
112 num_to_check = 8 - start;
113
114 return ((int)(png_memcmp(&sig[start], &png_sig[start], num_to_check)));
115 }
116
117 /* (Obsolete) function to check signature bytes. It does not allow one
118 * to check a partial signature. This function might be removed in the
119 * future - use png_sig_cmp(). Returns true (nonzero) if the file is a PNG.
120 */
121 int
122 png_check_sig(png_bytep sig, int num)
123 {
124 return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));
125 }
126
127 /* Function to allocate memory for zlib. */
128 voidpf
129 png_zalloc(voidpf png_ptr, uInt items, uInt size)
130 {
131 png_uint_32 num_bytes = (png_uint_32)items * size;
132 png_voidp ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
133
134 if (num_bytes > (png_uint_32)0x8000L)
135 {
136 png_memset(ptr, 0, (png_size_t)0x8000L);
137 png_memset((png_bytep)ptr + (png_size_t)0x8000L, 0,
138 (png_size_t)(num_bytes - (png_uint_32)0x8000L));
139 }
140 else
141 {
142 png_memset(ptr, 0, (png_size_t)num_bytes);
143 }
144 return ((voidpf)ptr);
145 }
146
147 /* function to free memory for zlib */
148 void
149 png_zfree(voidpf png_ptr, voidpf ptr)
150 {
151 png_free((png_structp)png_ptr, (png_voidp)ptr);
152 }
153
154 /* Reset the CRC variable to 32 bits of 1's. Care must be taken
155 * in case CRC is > 32 bits to leave the top bits 0.
156 */
157 void
158 png_reset_crc(png_structp png_ptr)
159 {
160 png_ptr->crc = crc32(0, Z_NULL, 0);
161 }
162
163 /* Calculate the CRC over a section of data. We can only pass as
164 * much data to this routine as the largest single buffer size. We
165 * also check that this data will actually be used before going to the
166 * trouble of calculating it.
167 */
168 void
169 png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)
170 {
171 int need_crc = 1;
172
173 if (png_ptr->chunk_name[0] & 0x20) /* ancillary */
174 {
175 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
176 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
177 need_crc = 0;
178 }
179 else /* critical */
180 {
181 if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
182 need_crc = 0;
183 }
184
185 if (need_crc)
186 png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length);
187 }
188
189 /* Allocate the memory for an info_struct for the application. We don't
190 * really need the png_ptr, but it could potentially be useful in the
191 * future. This should be used in favour of malloc(sizeof(png_info))
192 * and png_info_init() so that applications that want to use a shared
193 * libpng don't have to be recompiled if png_info changes size.
194 */
195 png_infop
196 png_create_info_struct(png_structp png_ptr)
197 {
198 png_infop info_ptr;
199
200 png_debug(1, "in png_create_info_struct\n");
201 if(png_ptr == NULL) return (NULL);
202 #ifdef PNG_USER_MEM_SUPPORTED
203 if ((info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
204 png_ptr->malloc_fn)) != NULL)
205 #else
206 if ((info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO)) != NULL)
207 #endif
208 {
209 png_info_init(info_ptr);
210 }
211
212 return (info_ptr);
213 }
214
215 /* This function frees the memory associated with a single info struct.
216 * Normally, one would use either png_destroy_read_struct() or
217 * png_destroy_write_struct() to free an info struct, but this may be
218 * useful for some applications.
219 */
220 void
221 png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
222 {
223 png_infop info_ptr = NULL;
224
225 png_debug(1, "in png_destroy_info_struct\n");
226 if (info_ptr_ptr != NULL)
227 info_ptr = *info_ptr_ptr;
228
229 if (info_ptr != NULL)
230 {
231 png_info_destroy(png_ptr, info_ptr);
232
233 #ifdef PNG_USER_MEM_SUPPORTED
234 png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn);
235 #else
236 png_destroy_struct((png_voidp)info_ptr);
237 #endif
238 *info_ptr_ptr = (png_infop)NULL;
239 }
240 }
241
242 /* Initialize the info structure. This is now an internal function (0.89)
243 * and applications using it are urged to use png_create_info_struct()
244 * instead.
245 */
246 void
247 png_info_init(png_infop info_ptr)
248 {
249 png_debug(1, "in png_info_init\n");
250 /* set everything to 0 */
251 png_memset(info_ptr, 0, sizeof (png_info));
252 }
253
254 /* This is an internal routine to free any memory that the info struct is
255 * pointing to before re-using it or freeing the struct itself. Recall
256 * that png_free() checks for NULL pointers for us.
257 */
258 void
259 png_info_destroy(png_structp png_ptr, png_infop info_ptr)
260 {
261 #if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
262 png_debug(1, "in png_info_destroy\n");
263 if (info_ptr->text != NULL)
264 {
265 int i;
266 for (i = 0; i < info_ptr->num_text; i++)
267 {
268 png_free(png_ptr, info_ptr->text[i].key);
269 }
270 png_free(png_ptr, info_ptr->text);
271 }
272 #endif
273 #if defined(PNG_READ_pCAL_SUPPORTED)
274 png_free(png_ptr, info_ptr->pcal_purpose);
275 png_free(png_ptr, info_ptr->pcal_units);
276 if (info_ptr->pcal_params != NULL)
277 {
278 int i;
279 for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
280 {
281 png_free(png_ptr, info_ptr->pcal_params[i]);
282 }
283 png_free(png_ptr, info_ptr->pcal_params);
284 }
285 #endif
286
287 png_info_init(info_ptr);
288 }
289
290 /* This function returns a pointer to the io_ptr associated with the user
291 * functions. The application should free any memory associated with this
292 * pointer before png_write_destroy() or png_read_destroy() are called.
293 */
294 png_voidp
295 png_get_io_ptr(png_structp png_ptr)
296 {
297 return (png_ptr->io_ptr);
298 }
299
300 #if !defined(PNG_NO_STDIO)
301 /* Initialize the default input/output functions for the PNG file. If you
302 * use your own read or write routines, you can call either png_set_read_fn()
303 * or png_set_write_fn() instead of png_init_io().
304 */
305 void
306 png_init_io(png_structp png_ptr, FILE *fp)
307 {
308 png_debug(1, "in png_init_io\n");
309 png_ptr->io_ptr = (png_voidp)fp;
310 }
311 #endif
312
313 #if defined(PNG_TIME_RFC1123_SUPPORTED)
314 /* Convert the supplied time into an RFC 1123 string suitable for use in
315 * a "Creation Time" or other text-based time string.
316 */
317 png_charp
318 png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
319 {
320 static PNG_CONST char short_months[12][4] =
321 {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
322 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
323
324 if (png_ptr->time_buffer == NULL)
325 {
326 png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
327 sizeof(char)));
328 }
329
330 #ifdef USE_FAR_KEYWORD
331 {
332 char near_time_buf[29];
333 sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000",
334 ptime->day % 32, short_months[(ptime->month - 1) % 12],
335 ptime->year, ptime->hour % 24, ptime->minute % 60,
336 ptime->second % 61);
337 png_memcpy(png_ptr->time_buffer, near_time_buf,
338 29*sizeof(char));
339 }
340 #else
341 sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000",
342 ptime->day % 32, short_months[(ptime->month - 1) % 12],
343 ptime->year, ptime->hour % 24, ptime->minute % 60,
344 ptime->second % 61);
345 #endif
346 return ((png_charp)png_ptr->time_buffer);
347 }
348 #endif /* PNG_TIME_RFC1123_SUPPORTED */
349
350 png_charp
351 png_get_copyright(png_structp png_ptr)
352 {
353 if(png_ptr == NULL)
354 /* silence compiler warning about unused png_ptr */ ;
355 return("\n libpng version 1.0.3 - January 14, 1999\n\
356 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.\n\
357 Copyright (c) 1996, 1997 Andreas Dilger\n\
358 Copyright (c) 1998, 1999, Glenn Randers-Pehrson\n");
359 }