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1 | |
2 | /* png.c - location for general purpose libpng functions | |
3 | * | |
a626cc03 | 4 | * libpng version 1.0.3 - January 14, 1999 |
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5 | * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. |
6 | * Copyright (c) 1996, 1997 Andreas Dilger | |
a626cc03 RR |
7 | * Copyright (c) 1998, 1999 Glenn Randers-Pehrson |
8 | * | |
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9 | */ |
10 | ||
11 | #define PNG_INTERNAL | |
12 | #define PNG_NO_EXTERN | |
a626cc03 | 13 | #include "png.h" |
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14 | |
15 | /* Version information for C files. This had better match the version | |
16 | * string defined in png.h. | |
17 | */ | |
a626cc03 RR |
18 | |
19 | char png_libpng_ver[12] = "1.0.3"; | |
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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 | |
a626cc03 RR |
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. | |
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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 | { | |
a626cc03 RR |
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); | |
c801d85f | 133 | |
a626cc03 | 134 | if (num_bytes > (png_uint_32)0x8000L) |
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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); | |
a626cc03 RR |
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 | |
c801d85f | 206 | if ((info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO)) != NULL) |
a626cc03 | 207 | #endif |
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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 | ||
a626cc03 RR |
233 | #ifdef PNG_USER_MEM_SUPPORTED |
234 | png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn); | |
235 | #else | |
c801d85f | 236 | png_destroy_struct((png_voidp)info_ptr); |
a626cc03 | 237 | #endif |
c801d85f KB |
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) | |
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262 | png_debug(1, "in png_info_destroy\n"); |
263 | if (info_ptr->text != NULL) | |
264 | { | |
a626cc03 | 265 | int i; |
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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 | { | |
a626cc03 | 278 | int i; |
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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 | |
a626cc03 RR |
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 | } |