1 2/* png.c - location for general purpose libpng functions 3 * 4 * Last changed in libpng 1.6.19 [November 12, 2015] 5 * Copyright (c) 1998-2002,2004,2006-2015 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#include "pngpriv.h" 15 16/* Generate a compiler error if there is an old png.h in the search path. */ 17typedef png_libpng_version_1_6_22beta03 Your_png_h_is_not_version_1_6_22beta03; 18 19/* Tells libpng that we have already handled the first "num_bytes" bytes 20 * of the PNG file signature. If the PNG data is embedded into another 21 * stream we can set num_bytes = 8 so that libpng will not attempt to read 22 * or write any of the magic bytes before it starts on the IHDR. 23 */ 24 25#ifdef PNG_READ_SUPPORTED 26void PNGAPI 27png_set_sig_bytes(png_structrp png_ptr, int num_bytes) 28{ 29 unsigned int nb = (unsigned int)num_bytes; 30 31 png_debug(1, "in png_set_sig_bytes"); 32 33 if (png_ptr == NULL) 34 return; 35 36 if (num_bytes < 0) 37 nb = 0; 38 39 if (nb > 8) 40 png_error(png_ptr, "Too many bytes for PNG signature"); 41 42 png_ptr->sig_bytes = (png_byte)nb; 43} 44 45/* Checks whether the supplied bytes match the PNG signature. We allow 46 * checking less than the full 8-byte signature so that those apps that 47 * already read the first few bytes of a file to determine the file type 48 * can simply check the remaining bytes for extra assurance. Returns 49 * an integer less than, equal to, or greater than zero if sig is found, 50 * respectively, to be less than, to match, or be greater than the correct 51 * PNG signature (this is the same behavior as strcmp, memcmp, etc). 52 */ 53int PNGAPI 54png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check) 55{ 56 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; 57 58 if (num_to_check > 8) 59 num_to_check = 8; 60 61 else if (num_to_check < 1) 62 return (-1); 63 64 if (start > 7) 65 return (-1); 66 67 if (start + num_to_check > 8) 68 num_to_check = 8 - start; 69 70 return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check))); 71} 72 73#endif /* READ */ 74 75#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) 76/* Function to allocate memory for zlib */ 77PNG_FUNCTION(voidpf /* PRIVATE */, 78png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED) 79{ 80 png_alloc_size_t num_bytes = size; 81 82 if (png_ptr == NULL) 83 return NULL; 84 85 if (items >= (~(png_alloc_size_t)0)/size) 86 { 87 png_warning (png_voidcast(png_structrp, png_ptr), 88 "Potential overflow in png_zalloc()"); 89 return NULL; 90 } 91 92 num_bytes *= items; 93 return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes); 94} 95 96/* Function to free memory for zlib */ 97void /* PRIVATE */ 98png_zfree(voidpf png_ptr, voidpf ptr) 99{ 100 png_free(png_voidcast(png_const_structrp,png_ptr), ptr); 101} 102 103/* Reset the CRC variable to 32 bits of 1's. Care must be taken 104 * in case CRC is > 32 bits to leave the top bits 0. 105 */ 106void /* PRIVATE */ 107png_reset_crc(png_structrp png_ptr) 108{ 109 /* The cast is safe because the crc is a 32-bit value. */ 110 png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0); 111} 112 113/* Calculate the CRC over a section of data. We can only pass as 114 * much data to this routine as the largest single buffer size. We 115 * also check that this data will actually be used before going to the 116 * trouble of calculating it. 117 */ 118void /* PRIVATE */ 119png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length) 120{ 121 int need_crc = 1; 122 123 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0) 124 { 125 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) == 126 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN)) 127 need_crc = 0; 128 } 129 130 else /* critical */ 131 { 132 if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0) 133 need_crc = 0; 134 } 135 136 /* 'uLong' is defined in zlib.h as unsigned long; this means that on some 137 * systems it is a 64-bit value. crc32, however, returns 32 bits so the 138 * following cast is safe. 'uInt' may be no more than 16 bits, so it is 139 * necessary to perform a loop here. 140 */ 141 if (need_crc != 0 && length > 0) 142 { 143 uLong crc = png_ptr->crc; /* Should never issue a warning */ 144 145 do 146 { 147 uInt safe_length = (uInt)length; 148#ifndef __COVERITY__ 149 if (safe_length == 0) 150 safe_length = (uInt)-1; /* evil, but safe */ 151#endif 152 153 crc = crc32(crc, ptr, safe_length); 154 155 /* The following should never issue compiler warnings; if they do the 156 * target system has characteristics that will probably violate other 157 * assumptions within the libpng code. 158 */ 159 ptr += safe_length; 160 length -= safe_length; 161 } 162 while (length > 0); 163 164 /* And the following is always safe because the crc is only 32 bits. */ 165 png_ptr->crc = (png_uint_32)crc; 166 } 167} 168 169/* Check a user supplied version number, called from both read and write 170 * functions that create a png_struct. 171 */ 172int 173png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver) 174{ 175 /* Libpng versions 1.0.0 and later are binary compatible if the version 176 * string matches through the second '.'; we must recompile any 177 * applications that use any older library version. 178 */ 179 180 if (user_png_ver != NULL) 181 { 182 int i = -1; 183 int found_dots = 0; 184 185 do 186 { 187 i++; 188 if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i]) 189 png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; 190 if (user_png_ver[i] == '.') 191 found_dots++; 192 } while (found_dots < 2 && user_png_ver[i] != 0 && 193 PNG_LIBPNG_VER_STRING[i] != 0); 194 } 195 196 else 197 png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; 198 199 if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0) 200 { 201#ifdef PNG_WARNINGS_SUPPORTED 202 size_t pos = 0; 203 char m[128]; 204 205 pos = png_safecat(m, (sizeof m), pos, 206 "Application built with libpng-"); 207 pos = png_safecat(m, (sizeof m), pos, user_png_ver); 208 pos = png_safecat(m, (sizeof m), pos, " but running with "); 209 pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING); 210 PNG_UNUSED(pos) 211 212 png_warning(png_ptr, m); 213#endif 214 215#ifdef PNG_ERROR_NUMBERS_SUPPORTED 216 png_ptr->flags = 0; 217#endif 218 219 return 0; 220 } 221 222 /* Success return. */ 223 return 1; 224} 225 226/* Generic function to create a png_struct for either read or write - this 227 * contains the common initialization. 228 */ 229PNG_FUNCTION(png_structp /* PRIVATE */, 230png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr, 231 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, 232 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED) 233{ 234 png_struct create_struct; 235# ifdef PNG_SETJMP_SUPPORTED 236 jmp_buf create_jmp_buf; 237# endif 238 239 /* This temporary stack-allocated structure is used to provide a place to 240 * build enough context to allow the user provided memory allocator (if any) 241 * to be called. 242 */ 243 memset(&create_struct, 0, (sizeof create_struct)); 244 245 /* Added at libpng-1.2.6 */ 246# ifdef PNG_USER_LIMITS_SUPPORTED 247 create_struct.user_width_max = PNG_USER_WIDTH_MAX; 248 create_struct.user_height_max = PNG_USER_HEIGHT_MAX; 249 250# ifdef PNG_USER_CHUNK_CACHE_MAX 251 /* Added at libpng-1.2.43 and 1.4.0 */ 252 create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX; 253# endif 254 255# ifdef PNG_USER_CHUNK_MALLOC_MAX 256 /* Added at libpng-1.2.43 and 1.4.1, required only for read but exists 257 * in png_struct regardless. 258 */ 259 create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX; 260# endif 261# endif 262 263 /* The following two API calls simply set fields in png_struct, so it is safe 264 * to do them now even though error handling is not yet set up. 265 */ 266# ifdef PNG_USER_MEM_SUPPORTED 267 png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn); 268# else 269 PNG_UNUSED(mem_ptr) 270 PNG_UNUSED(malloc_fn) 271 PNG_UNUSED(free_fn) 272# endif 273 274 /* (*error_fn) can return control to the caller after the error_ptr is set, 275 * this will result in a memory leak unless the error_fn does something 276 * extremely sophisticated. The design lacks merit but is implicit in the 277 * API. 278 */ 279 png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn); 280 281# ifdef PNG_SETJMP_SUPPORTED 282 if (!setjmp(create_jmp_buf)) 283# endif 284 { 285# ifdef PNG_SETJMP_SUPPORTED 286 /* Temporarily fake out the longjmp information until we have 287 * successfully completed this function. This only works if we have 288 * setjmp() support compiled in, but it is safe - this stuff should 289 * never happen. 290 */ 291 create_struct.jmp_buf_ptr = &create_jmp_buf; 292 create_struct.jmp_buf_size = 0; /*stack allocation*/ 293 create_struct.longjmp_fn = longjmp; 294# endif 295 /* Call the general version checker (shared with read and write code): 296 */ 297 if (png_user_version_check(&create_struct, user_png_ver) != 0) 298 { 299 png_structrp png_ptr = png_voidcast(png_structrp, 300 png_malloc_warn(&create_struct, (sizeof *png_ptr))); 301 302 if (png_ptr != NULL) 303 { 304 /* png_ptr->zstream holds a back-pointer to the png_struct, so 305 * this can only be done now: 306 */ 307 create_struct.zstream.zalloc = png_zalloc; 308 create_struct.zstream.zfree = png_zfree; 309 create_struct.zstream.opaque = png_ptr; 310 311# ifdef PNG_SETJMP_SUPPORTED 312 /* Eliminate the local error handling: */ 313 create_struct.jmp_buf_ptr = NULL; 314 create_struct.jmp_buf_size = 0; 315 create_struct.longjmp_fn = 0; 316# endif 317 318 *png_ptr = create_struct; 319 320 /* This is the successful return point */ 321 return png_ptr; 322 } 323 } 324 } 325 326 /* A longjmp because of a bug in the application storage allocator or a 327 * simple failure to allocate the png_struct. 328 */ 329 return NULL; 330} 331 332/* Allocate the memory for an info_struct for the application. */ 333PNG_FUNCTION(png_infop,PNGAPI 334png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED) 335{ 336 png_inforp info_ptr; 337 338 png_debug(1, "in png_create_info_struct"); 339 340 if (png_ptr == NULL) 341 return NULL; 342 343 /* Use the internal API that does not (or at least should not) error out, so 344 * that this call always returns ok. The application typically sets up the 345 * error handling *after* creating the info_struct because this is the way it 346 * has always been done in 'example.c'. 347 */ 348 info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr, 349 (sizeof *info_ptr))); 350 351 if (info_ptr != NULL) 352 memset(info_ptr, 0, (sizeof *info_ptr)); 353 354 return info_ptr; 355} 356 357/* This function frees the memory associated with a single info struct. 358 * Normally, one would use either png_destroy_read_struct() or 359 * png_destroy_write_struct() to free an info struct, but this may be 360 * useful for some applications. From libpng 1.6.0 this function is also used 361 * internally to implement the png_info release part of the 'struct' destroy 362 * APIs. This ensures that all possible approaches free the same data (all of 363 * it). 364 */ 365void PNGAPI 366png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr) 367{ 368 png_inforp info_ptr = NULL; 369 370 png_debug(1, "in png_destroy_info_struct"); 371 372 if (png_ptr == NULL) 373 return; 374 375 if (info_ptr_ptr != NULL) 376 info_ptr = *info_ptr_ptr; 377 378 if (info_ptr != NULL) 379 { 380 /* Do this first in case of an error below; if the app implements its own 381 * memory management this can lead to png_free calling png_error, which 382 * will abort this routine and return control to the app error handler. 383 * An infinite loop may result if it then tries to free the same info 384 * ptr. 385 */ 386 *info_ptr_ptr = NULL; 387 388 png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1); 389 memset(info_ptr, 0, (sizeof *info_ptr)); 390 png_free(png_ptr, info_ptr); 391 } 392} 393 394/* Initialize the info structure. This is now an internal function (0.89) 395 * and applications using it are urged to use png_create_info_struct() 396 * instead. Use deprecated in 1.6.0, internal use removed (used internally it 397 * is just a memset). 398 * 399 * NOTE: it is almost inconceivable that this API is used because it bypasses 400 * the user-memory mechanism and the user error handling/warning mechanisms in 401 * those cases where it does anything other than a memset. 402 */ 403PNG_FUNCTION(void,PNGAPI 404png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size), 405 PNG_DEPRECATED) 406{ 407 png_inforp info_ptr = *ptr_ptr; 408 409 png_debug(1, "in png_info_init_3"); 410 411 if (info_ptr == NULL) 412 return; 413 414 if ((sizeof (png_info)) > png_info_struct_size) 415 { 416 *ptr_ptr = NULL; 417 /* The following line is why this API should not be used: */ 418 free(info_ptr); 419 info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL, 420 (sizeof *info_ptr))); 421 if (info_ptr == NULL) 422 return; 423 *ptr_ptr = info_ptr; 424 } 425 426 /* Set everything to 0 */ 427 memset(info_ptr, 0, (sizeof *info_ptr)); 428} 429 430/* The following API is not called internally */ 431void PNGAPI 432png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr, 433 int freer, png_uint_32 mask) 434{ 435 png_debug(1, "in png_data_freer"); 436 437 if (png_ptr == NULL || info_ptr == NULL) 438 return; 439 440 if (freer == PNG_DESTROY_WILL_FREE_DATA) 441 info_ptr->free_me |= mask; 442 443 else if (freer == PNG_USER_WILL_FREE_DATA) 444 info_ptr->free_me &= ~mask; 445 446 else 447 png_error(png_ptr, "Unknown freer parameter in png_data_freer"); 448} 449 450void PNGAPI 451png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask, 452 int num) 453{ 454 png_debug(1, "in png_free_data"); 455 456 if (png_ptr == NULL || info_ptr == NULL) 457 return; 458 459#ifdef PNG_TEXT_SUPPORTED 460 /* Free text item num or (if num == -1) all text items */ 461 if (info_ptr->text != 0 && 462 ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0) 463 { 464 if (num != -1) 465 { 466 png_free(png_ptr, info_ptr->text[num].key); 467 info_ptr->text[num].key = NULL; 468 } 469 470 else 471 { 472 int i; 473 474 for (i = 0; i < info_ptr->num_text; i++) 475 png_free(png_ptr, info_ptr->text[i].key); 476 477 png_free(png_ptr, info_ptr->text); 478 info_ptr->text = NULL; 479 info_ptr->num_text = 0; 480 } 481 } 482#endif 483 484#ifdef PNG_tRNS_SUPPORTED 485 /* Free any tRNS entry */ 486 if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0) 487 { 488 info_ptr->valid &= ~PNG_INFO_tRNS; 489 png_free(png_ptr, info_ptr->trans_alpha); 490 info_ptr->trans_alpha = NULL; 491 info_ptr->num_trans = 0; 492 } 493#endif 494 495#ifdef PNG_sCAL_SUPPORTED 496 /* Free any sCAL entry */ 497 if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0) 498 { 499 png_free(png_ptr, info_ptr->scal_s_width); 500 png_free(png_ptr, info_ptr->scal_s_height); 501 info_ptr->scal_s_width = NULL; 502 info_ptr->scal_s_height = NULL; 503 info_ptr->valid &= ~PNG_INFO_sCAL; 504 } 505#endif 506 507#ifdef PNG_pCAL_SUPPORTED 508 /* Free any pCAL entry */ 509 if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0) 510 { 511 png_free(png_ptr, info_ptr->pcal_purpose); 512 png_free(png_ptr, info_ptr->pcal_units); 513 info_ptr->pcal_purpose = NULL; 514 info_ptr->pcal_units = NULL; 515 516 if (info_ptr->pcal_params != NULL) 517 { 518 int i; 519 520 for (i = 0; i < info_ptr->pcal_nparams; i++) 521 png_free(png_ptr, info_ptr->pcal_params[i]); 522 523 png_free(png_ptr, info_ptr->pcal_params); 524 info_ptr->pcal_params = NULL; 525 } 526 info_ptr->valid &= ~PNG_INFO_pCAL; 527 } 528#endif 529 530#ifdef PNG_iCCP_SUPPORTED 531 /* Free any profile entry */ 532 if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0) 533 { 534 png_free(png_ptr, info_ptr->iccp_name); 535 png_free(png_ptr, info_ptr->iccp_profile); 536 info_ptr->iccp_name = NULL; 537 info_ptr->iccp_profile = NULL; 538 info_ptr->valid &= ~PNG_INFO_iCCP; 539 } 540#endif 541 542#ifdef PNG_sPLT_SUPPORTED 543 /* Free a given sPLT entry, or (if num == -1) all sPLT entries */ 544 if (info_ptr->splt_palettes != 0 && 545 ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0) 546 { 547 if (num != -1) 548 { 549 png_free(png_ptr, info_ptr->splt_palettes[num].name); 550 png_free(png_ptr, info_ptr->splt_palettes[num].entries); 551 info_ptr->splt_palettes[num].name = NULL; 552 info_ptr->splt_palettes[num].entries = NULL; 553 } 554 555 else 556 { 557 int i; 558 559 for (i = 0; i < info_ptr->splt_palettes_num; i++) 560 { 561 png_free(png_ptr, info_ptr->splt_palettes[i].name); 562 png_free(png_ptr, info_ptr->splt_palettes[i].entries); 563 } 564 565 png_free(png_ptr, info_ptr->splt_palettes); 566 info_ptr->splt_palettes = NULL; 567 info_ptr->splt_palettes_num = 0; 568 info_ptr->valid &= ~PNG_INFO_sPLT; 569 } 570 } 571#endif 572 573#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED 574 if (info_ptr->unknown_chunks != 0 && 575 ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0) 576 { 577 if (num != -1) 578 { 579 png_free(png_ptr, info_ptr->unknown_chunks[num].data); 580 info_ptr->unknown_chunks[num].data = NULL; 581 } 582 583 else 584 { 585 int i; 586 587 for (i = 0; i < info_ptr->unknown_chunks_num; i++) 588 png_free(png_ptr, info_ptr->unknown_chunks[i].data); 589 590 png_free(png_ptr, info_ptr->unknown_chunks); 591 info_ptr->unknown_chunks = NULL; 592 info_ptr->unknown_chunks_num = 0; 593 } 594 } 595#endif 596 597#ifdef PNG_hIST_SUPPORTED 598 /* Free any hIST entry */ 599 if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0) 600 { 601 png_free(png_ptr, info_ptr->hist); 602 info_ptr->hist = NULL; 603 info_ptr->valid &= ~PNG_INFO_hIST; 604 } 605#endif 606 607 /* Free any PLTE entry that was internally allocated */ 608 if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0) 609 { 610 png_free(png_ptr, info_ptr->palette); 611 info_ptr->palette = NULL; 612 info_ptr->valid &= ~PNG_INFO_PLTE; 613 info_ptr->num_palette = 0; 614 } 615 616#ifdef PNG_INFO_IMAGE_SUPPORTED 617 /* Free any image bits attached to the info structure */ 618 if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0) 619 { 620 if (info_ptr->row_pointers != 0) 621 { 622 png_uint_32 row; 623 for (row = 0; row < info_ptr->height; row++) 624 png_free(png_ptr, info_ptr->row_pointers[row]); 625 626 png_free(png_ptr, info_ptr->row_pointers); 627 info_ptr->row_pointers = NULL; 628 } 629 info_ptr->valid &= ~PNG_INFO_IDAT; 630 } 631#endif 632 633 if (num != -1) 634 mask &= ~PNG_FREE_MUL; 635 636 info_ptr->free_me &= ~mask; 637} 638#endif /* READ || WRITE */ 639 640/* This function returns a pointer to the io_ptr associated with the user 641 * functions. The application should free any memory associated with this 642 * pointer before png_write_destroy() or png_read_destroy() are called. 643 */ 644png_voidp PNGAPI 645png_get_io_ptr(png_const_structrp png_ptr) 646{ 647 if (png_ptr == NULL) 648 return (NULL); 649 650 return (png_ptr->io_ptr); 651} 652 653#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) 654# ifdef PNG_STDIO_SUPPORTED 655/* Initialize the default input/output functions for the PNG file. If you 656 * use your own read or write routines, you can call either png_set_read_fn() 657 * or png_set_write_fn() instead of png_init_io(). If you have defined 658 * PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a 659 * function of your own because "FILE *" isn't necessarily available. 660 */ 661void PNGAPI 662png_init_io(png_structrp png_ptr, png_FILE_p fp) 663{ 664 png_debug(1, "in png_init_io"); 665 666 if (png_ptr == NULL) 667 return; 668 669 png_ptr->io_ptr = (png_voidp)fp; 670} 671# endif 672 673# ifdef PNG_SAVE_INT_32_SUPPORTED 674/* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90 675 * defines a cast of a signed integer to an unsigned integer either to preserve 676 * the value, if it is positive, or to calculate: 677 * 678 * (UNSIGNED_MAX+1) + integer 679 * 680 * Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the 681 * negative integral value is added the result will be an unsigned value 682 * correspnding to the 2's complement representation. 683 */ 684void PNGAPI 685png_save_int_32(png_bytep buf, png_int_32 i) 686{ 687 png_save_uint_32(buf, i); 688} 689# endif 690 691# ifdef PNG_TIME_RFC1123_SUPPORTED 692/* Convert the supplied time into an RFC 1123 string suitable for use in 693 * a "Creation Time" or other text-based time string. 694 */ 695int PNGAPI 696png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime) 697{ 698 static PNG_CONST char short_months[12][4] = 699 {"Jan", "Feb", "Mar", "Apr", "May", "Jun", 700 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; 701 702 if (out == NULL) 703 return 0; 704 705 if (ptime->year > 9999 /* RFC1123 limitation */ || 706 ptime->month == 0 || ptime->month > 12 || 707 ptime->day == 0 || ptime->day > 31 || 708 ptime->hour > 23 || ptime->minute > 59 || 709 ptime->second > 60) 710 return 0; 711 712 { 713 size_t pos = 0; 714 char number_buf[5]; /* enough for a four-digit year */ 715 716# define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string)) 717# define APPEND_NUMBER(format, value)\ 718 APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value))) 719# define APPEND(ch) if (pos < 28) out[pos++] = (ch) 720 721 APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day); 722 APPEND(' '); 723 APPEND_STRING(short_months[(ptime->month - 1)]); 724 APPEND(' '); 725 APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year); 726 APPEND(' '); 727 APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour); 728 APPEND(':'); 729 APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute); 730 APPEND(':'); 731 APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second); 732 APPEND_STRING(" +0000"); /* This reliably terminates the buffer */ 733 PNG_UNUSED (pos) 734 735# undef APPEND 736# undef APPEND_NUMBER 737# undef APPEND_STRING 738 } 739 740 return 1; 741} 742 743# if PNG_LIBPNG_VER < 10700 744/* To do: remove the following from libpng-1.7 */ 745/* Original API that uses a private buffer in png_struct. 746 * Deprecated because it causes png_struct to carry a spurious temporary 747 * buffer (png_struct::time_buffer), better to have the caller pass this in. 748 */ 749png_const_charp PNGAPI 750png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime) 751{ 752 if (png_ptr != NULL) 753 { 754 /* The only failure above if png_ptr != NULL is from an invalid ptime */ 755 if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0) 756 png_warning(png_ptr, "Ignoring invalid time value"); 757 758 else 759 return png_ptr->time_buffer; 760 } 761 762 return NULL; 763} 764# endif /* LIBPNG_VER < 10700 */ 765# endif /* TIME_RFC1123 */ 766 767#endif /* READ || WRITE */ 768 769png_const_charp PNGAPI 770png_get_copyright(png_const_structrp png_ptr) 771{ 772 PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ 773#ifdef PNG_STRING_COPYRIGHT 774 return PNG_STRING_COPYRIGHT 775#else 776# ifdef __STDC__ 777 return PNG_STRING_NEWLINE \ 778 "libpng version 1.6.22beta03 - February 8, 2016" PNG_STRING_NEWLINE \ 779 "Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson" \ 780 PNG_STRING_NEWLINE \ 781 "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \ 782 "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \ 783 PNG_STRING_NEWLINE; 784# else 785 return "libpng version 1.6.22beta03 - February 8, 2016\ 786 Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson\ 787 Copyright (c) 1996-1997 Andreas Dilger\ 788 Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc."; 789# endif 790#endif 791} 792 793/* The following return the library version as a short string in the 794 * format 1.0.0 through 99.99.99zz. To get the version of *.h files 795 * used with your application, print out PNG_LIBPNG_VER_STRING, which 796 * is defined in png.h. 797 * Note: now there is no difference between png_get_libpng_ver() and 798 * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard, 799 * it is guaranteed that png.c uses the correct version of png.h. 800 */ 801png_const_charp PNGAPI 802png_get_libpng_ver(png_const_structrp png_ptr) 803{ 804 /* Version of *.c files used when building libpng */ 805 return png_get_header_ver(png_ptr); 806} 807 808png_const_charp PNGAPI 809png_get_header_ver(png_const_structrp png_ptr) 810{ 811 /* Version of *.h files used when building libpng */ 812 PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ 813 return PNG_LIBPNG_VER_STRING; 814} 815 816png_const_charp PNGAPI 817png_get_header_version(png_const_structrp png_ptr) 818{ 819 /* Returns longer string containing both version and date */ 820 PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ 821#ifdef __STDC__ 822 return PNG_HEADER_VERSION_STRING 823# ifndef PNG_READ_SUPPORTED 824 " (NO READ SUPPORT)" 825# endif 826 PNG_STRING_NEWLINE; 827#else 828 return PNG_HEADER_VERSION_STRING; 829#endif 830} 831 832#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED 833/* NOTE: this routine is not used internally! */ 834/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth 835 * large of png_color. This lets grayscale images be treated as 836 * paletted. Most useful for gamma correction and simplification 837 * of code. This API is not used internally. 838 */ 839void PNGAPI 840png_build_grayscale_palette(int bit_depth, png_colorp palette) 841{ 842 int num_palette; 843 int color_inc; 844 int i; 845 int v; 846 847 png_debug(1, "in png_do_build_grayscale_palette"); 848 849 if (palette == NULL) 850 return; 851 852 switch (bit_depth) 853 { 854 case 1: 855 num_palette = 2; 856 color_inc = 0xff; 857 break; 858 859 case 2: 860 num_palette = 4; 861 color_inc = 0x55; 862 break; 863 864 case 4: 865 num_palette = 16; 866 color_inc = 0x11; 867 break; 868 869 case 8: 870 num_palette = 256; 871 color_inc = 1; 872 break; 873 874 default: 875 num_palette = 0; 876 color_inc = 0; 877 break; 878 } 879 880 for (i = 0, v = 0; i < num_palette; i++, v += color_inc) 881 { 882 palette[i].red = (png_byte)(v & 0xff); 883 palette[i].green = (png_byte)(v & 0xff); 884 palette[i].blue = (png_byte)(v & 0xff); 885 } 886} 887#endif 888 889#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED 890int PNGAPI 891png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name) 892{ 893 /* Check chunk_name and return "keep" value if it's on the list, else 0 */ 894 png_const_bytep p, p_end; 895 896 if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0) 897 return PNG_HANDLE_CHUNK_AS_DEFAULT; 898 899 p_end = png_ptr->chunk_list; 900 p = p_end + png_ptr->num_chunk_list*5; /* beyond end */ 901 902 /* The code is the fifth byte after each four byte string. Historically this 903 * code was always searched from the end of the list, this is no longer 904 * necessary because the 'set' routine handles duplicate entries correcty. 905 */ 906 do /* num_chunk_list > 0, so at least one */ 907 { 908 p -= 5; 909 910 if (memcmp(chunk_name, p, 4) == 0) 911 return p[4]; 912 } 913 while (p > p_end); 914 915 /* This means that known chunks should be processed and unknown chunks should 916 * be handled according to the value of png_ptr->unknown_default; this can be 917 * confusing because, as a result, there are two levels of defaulting for 918 * unknown chunks. 919 */ 920 return PNG_HANDLE_CHUNK_AS_DEFAULT; 921} 922 923#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\ 924 defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED) 925int /* PRIVATE */ 926png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name) 927{ 928 png_byte chunk_string[5]; 929 930 PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name); 931 return png_handle_as_unknown(png_ptr, chunk_string); 932} 933#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */ 934#endif /* SET_UNKNOWN_CHUNKS */ 935 936#ifdef PNG_READ_SUPPORTED 937/* This function, added to libpng-1.0.6g, is untested. */ 938int PNGAPI 939png_reset_zstream(png_structrp png_ptr) 940{ 941 if (png_ptr == NULL) 942 return Z_STREAM_ERROR; 943 944 /* WARNING: this resets the window bits to the maximum! */ 945 return (inflateReset(&png_ptr->zstream)); 946} 947#endif /* READ */ 948 949/* This function was added to libpng-1.0.7 */ 950png_uint_32 PNGAPI 951png_access_version_number(void) 952{ 953 /* Version of *.c files used when building libpng */ 954 return((png_uint_32)PNG_LIBPNG_VER); 955} 956 957#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) 958/* Ensure that png_ptr->zstream.msg holds some appropriate error message string. 959 * If it doesn't 'ret' is used to set it to something appropriate, even in cases 960 * like Z_OK or Z_STREAM_END where the error code is apparently a success code. 961 */ 962void /* PRIVATE */ 963png_zstream_error(png_structrp png_ptr, int ret) 964{ 965 /* Translate 'ret' into an appropriate error string, priority is given to the 966 * one in zstream if set. This always returns a string, even in cases like 967 * Z_OK or Z_STREAM_END where the error code is a success code. 968 */ 969 if (png_ptr->zstream.msg == NULL) switch (ret) 970 { 971 default: 972 case Z_OK: 973 png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code"); 974 break; 975 976 case Z_STREAM_END: 977 /* Normal exit */ 978 png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream"); 979 break; 980 981 case Z_NEED_DICT: 982 /* This means the deflate stream did not have a dictionary; this 983 * indicates a bogus PNG. 984 */ 985 png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary"); 986 break; 987 988 case Z_ERRNO: 989 /* gz APIs only: should not happen */ 990 png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error"); 991 break; 992 993 case Z_STREAM_ERROR: 994 /* internal libpng error */ 995 png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib"); 996 break; 997 998 case Z_DATA_ERROR: 999 png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream"); 1000 break; 1001 1002 case Z_MEM_ERROR: 1003 png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory"); 1004 break; 1005 1006 case Z_BUF_ERROR: 1007 /* End of input or output; not a problem if the caller is doing 1008 * incremental read or write. 1009 */ 1010 png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated"); 1011 break; 1012 1013 case Z_VERSION_ERROR: 1014 png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version"); 1015 break; 1016 1017 case PNG_UNEXPECTED_ZLIB_RETURN: 1018 /* Compile errors here mean that zlib now uses the value co-opted in 1019 * pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above 1020 * and change pngpriv.h. Note that this message is "... return", 1021 * whereas the default/Z_OK one is "... return code". 1022 */ 1023 png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return"); 1024 break; 1025 } 1026} 1027 1028/* png_convert_size: a PNGAPI but no longer in png.h, so deleted 1029 * at libpng 1.5.5! 1030 */ 1031 1032/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */ 1033#ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */ 1034static int 1035png_colorspace_check_gamma(png_const_structrp png_ptr, 1036 png_colorspacerp colorspace, png_fixed_point gAMA, int from) 1037 /* This is called to check a new gamma value against an existing one. The 1038 * routine returns false if the new gamma value should not be written. 1039 * 1040 * 'from' says where the new gamma value comes from: 1041 * 1042 * 0: the new gamma value is the libpng estimate for an ICC profile 1043 * 1: the new gamma value comes from a gAMA chunk 1044 * 2: the new gamma value comes from an sRGB chunk 1045 */ 1046{ 1047 png_fixed_point gtest; 1048 1049 if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 && 1050 (png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) == 0 || 1051 png_gamma_significant(gtest) != 0)) 1052 { 1053 /* Either this is an sRGB image, in which case the calculated gamma 1054 * approximation should match, or this is an image with a profile and the 1055 * value libpng calculates for the gamma of the profile does not match the 1056 * value recorded in the file. The former, sRGB, case is an error, the 1057 * latter is just a warning. 1058 */ 1059 if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2) 1060 { 1061 png_chunk_report(png_ptr, "gamma value does not match sRGB", 1062 PNG_CHUNK_ERROR); 1063 /* Do not overwrite an sRGB value */ 1064 return from == 2; 1065 } 1066 1067 else /* sRGB tag not involved */ 1068 { 1069 png_chunk_report(png_ptr, "gamma value does not match libpng estimate", 1070 PNG_CHUNK_WARNING); 1071 return from == 1; 1072 } 1073 } 1074 1075 return 1; 1076} 1077 1078void /* PRIVATE */ 1079png_colorspace_set_gamma(png_const_structrp png_ptr, 1080 png_colorspacerp colorspace, png_fixed_point gAMA) 1081{ 1082 /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't 1083 * occur. Since the fixed point representation is asymetrical it is 1084 * possible for 1/gamma to overflow the limit of 21474 and this means the 1085 * gamma value must be at least 5/100000 and hence at most 20000.0. For 1086 * safety the limits here are a little narrower. The values are 0.00016 to 1087 * 6250.0, which are truly ridiculous gamma values (and will produce 1088 * displays that are all black or all white.) 1089 * 1090 * In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk 1091 * handling code, which only required the value to be >0. 1092 */ 1093 png_const_charp errmsg; 1094 1095 if (gAMA < 16 || gAMA > 625000000) 1096 errmsg = "gamma value out of range"; 1097 1098# ifdef PNG_READ_gAMA_SUPPORTED 1099 /* Allow the application to set the gamma value more than once */ 1100 else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 && 1101 (colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0) 1102 errmsg = "duplicate"; 1103# endif 1104 1105 /* Do nothing if the colorspace is already invalid */ 1106 else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0) 1107 return; 1108 1109 else 1110 { 1111 if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA, 1112 1/*from gAMA*/) != 0) 1113 { 1114 /* Store this gamma value. */ 1115 colorspace->gamma = gAMA; 1116 colorspace->flags |= 1117 (PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA); 1118 } 1119 1120 /* At present if the check_gamma test fails the gamma of the colorspace is 1121 * not updated however the colorspace is not invalidated. This 1122 * corresponds to the case where the existing gamma comes from an sRGB 1123 * chunk or profile. An error message has already been output. 1124 */ 1125 return; 1126 } 1127 1128 /* Error exit - errmsg has been set. */ 1129 colorspace->flags |= PNG_COLORSPACE_INVALID; 1130 png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR); 1131} 1132 1133void /* PRIVATE */ 1134png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr) 1135{ 1136 if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0) 1137 { 1138 /* Everything is invalid */ 1139 info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB| 1140 PNG_INFO_iCCP); 1141 1142# ifdef PNG_COLORSPACE_SUPPORTED 1143 /* Clean up the iCCP profile now if it won't be used. */ 1144 png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/); 1145# else 1146 PNG_UNUSED(png_ptr) 1147# endif 1148 } 1149 1150 else 1151 { 1152# ifdef PNG_COLORSPACE_SUPPORTED 1153 /* Leave the INFO_iCCP flag set if the pngset.c code has already set 1154 * it; this allows a PNG to contain a profile which matches sRGB and 1155 * yet still have that profile retrievable by the application. 1156 */ 1157 if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0) 1158 info_ptr->valid |= PNG_INFO_sRGB; 1159 1160 else 1161 info_ptr->valid &= ~PNG_INFO_sRGB; 1162 1163 if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0) 1164 info_ptr->valid |= PNG_INFO_cHRM; 1165 1166 else 1167 info_ptr->valid &= ~PNG_INFO_cHRM; 1168# endif 1169 1170 if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0) 1171 info_ptr->valid |= PNG_INFO_gAMA; 1172 1173 else 1174 info_ptr->valid &= ~PNG_INFO_gAMA; 1175 } 1176} 1177 1178#ifdef PNG_READ_SUPPORTED 1179void /* PRIVATE */ 1180png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr) 1181{ 1182 if (info_ptr == NULL) /* reduce code size; check here not in the caller */ 1183 return; 1184 1185 info_ptr->colorspace = png_ptr->colorspace; 1186 png_colorspace_sync_info(png_ptr, info_ptr); 1187} 1188#endif 1189#endif /* GAMMA */ 1190 1191#ifdef PNG_COLORSPACE_SUPPORTED 1192/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for 1193 * cHRM, as opposed to using chromaticities. These internal APIs return 1194 * non-zero on a parameter error. The X, Y and Z values are required to be 1195 * positive and less than 1.0. 1196 */ 1197static int 1198png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ) 1199{ 1200 png_int_32 d, dwhite, whiteX, whiteY; 1201 1202 d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z; 1203 if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0) 1204 return 1; 1205 if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0) 1206 return 1; 1207 dwhite = d; 1208 whiteX = XYZ->red_X; 1209 whiteY = XYZ->red_Y; 1210 1211 d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z; 1212 if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0) 1213 return 1; 1214 if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0) 1215 return 1; 1216 dwhite += d; 1217 whiteX += XYZ->green_X; 1218 whiteY += XYZ->green_Y; 1219 1220 d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z; 1221 if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0) 1222 return 1; 1223 if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0) 1224 return 1; 1225 dwhite += d; 1226 whiteX += XYZ->blue_X; 1227 whiteY += XYZ->blue_Y; 1228 1229 /* The reference white is simply the sum of the end-point (X,Y,Z) vectors, 1230 * thus: 1231 */ 1232 if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0) 1233 return 1; 1234 if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0) 1235 return 1; 1236 1237 return 0; 1238} 1239 1240static int 1241png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy) 1242{ 1243 png_fixed_point red_inverse, green_inverse, blue_scale; 1244 png_fixed_point left, right, denominator; 1245 1246 /* Check xy and, implicitly, z. Note that wide gamut color spaces typically 1247 * have end points with 0 tristimulus values (these are impossible end 1248 * points, but they are used to cover the possible colors). We check 1249 * xy->whitey against 5, not 0, to avoid a possible integer overflow. 1250 */ 1251 if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1; 1252 if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1; 1253 if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1; 1254 if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1; 1255 if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1; 1256 if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1; 1257 if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1; 1258 if (xy->whitey < 5 || xy->whitey > PNG_FP_1-xy->whitex) return 1; 1259 1260 /* The reverse calculation is more difficult because the original tristimulus 1261 * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8 1262 * derived values were recorded in the cHRM chunk; 1263 * (red,green,blue,white)x(x,y). This loses one degree of freedom and 1264 * therefore an arbitrary ninth value has to be introduced to undo the 1265 * original transformations. 1266 * 1267 * Think of the original end-points as points in (X,Y,Z) space. The 1268 * chromaticity values (c) have the property: 1269 * 1270 * C 1271 * c = --------- 1272 * X + Y + Z 1273 * 1274 * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the 1275 * three chromaticity values (x,y,z) for each end-point obey the 1276 * relationship: 1277 * 1278 * x + y + z = 1 1279 * 1280 * This describes the plane in (X,Y,Z) space that intersects each axis at the 1281 * value 1.0; call this the chromaticity plane. Thus the chromaticity 1282 * calculation has scaled each end-point so that it is on the x+y+z=1 plane 1283 * and chromaticity is the intersection of the vector from the origin to the 1284 * (X,Y,Z) value with the chromaticity plane. 1285 * 1286 * To fully invert the chromaticity calculation we would need the three 1287 * end-point scale factors, (red-scale, green-scale, blue-scale), but these 1288 * were not recorded. Instead we calculated the reference white (X,Y,Z) and 1289 * recorded the chromaticity of this. The reference white (X,Y,Z) would have 1290 * given all three of the scale factors since: 1291 * 1292 * color-C = color-c * color-scale 1293 * white-C = red-C + green-C + blue-C 1294 * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale 1295 * 1296 * But cHRM records only white-x and white-y, so we have lost the white scale 1297 * factor: 1298 * 1299 * white-C = white-c*white-scale 1300 * 1301 * To handle this the inverse transformation makes an arbitrary assumption 1302 * about white-scale: 1303 * 1304 * Assume: white-Y = 1.0 1305 * Hence: white-scale = 1/white-y 1306 * Or: red-Y + green-Y + blue-Y = 1.0 1307 * 1308 * Notice the last statement of the assumption gives an equation in three of 1309 * the nine values we want to calculate. 8 more equations come from the 1310 * above routine as summarised at the top above (the chromaticity 1311 * calculation): 1312 * 1313 * Given: color-x = color-X / (color-X + color-Y + color-Z) 1314 * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0 1315 * 1316 * This is 9 simultaneous equations in the 9 variables "color-C" and can be 1317 * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix 1318 * determinants, however this is not as bad as it seems because only 28 of 1319 * the total of 90 terms in the various matrices are non-zero. Nevertheless 1320 * Cramer's rule is notoriously numerically unstable because the determinant 1321 * calculation involves the difference of large, but similar, numbers. It is 1322 * difficult to be sure that the calculation is stable for real world values 1323 * and it is certain that it becomes unstable where the end points are close 1324 * together. 1325 * 1326 * So this code uses the perhaps slightly less optimal but more 1327 * understandable and totally obvious approach of calculating color-scale. 1328 * 1329 * This algorithm depends on the precision in white-scale and that is 1330 * (1/white-y), so we can immediately see that as white-y approaches 0 the 1331 * accuracy inherent in the cHRM chunk drops off substantially. 1332 * 1333 * libpng arithmetic: a simple inversion of the above equations 1334 * ------------------------------------------------------------ 1335 * 1336 * white_scale = 1/white-y 1337 * white-X = white-x * white-scale 1338 * white-Y = 1.0 1339 * white-Z = (1 - white-x - white-y) * white_scale 1340 * 1341 * white-C = red-C + green-C + blue-C 1342 * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale 1343 * 1344 * This gives us three equations in (red-scale,green-scale,blue-scale) where 1345 * all the coefficients are now known: 1346 * 1347 * red-x*red-scale + green-x*green-scale + blue-x*blue-scale 1348 * = white-x/white-y 1349 * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1 1350 * red-z*red-scale + green-z*green-scale + blue-z*blue-scale 1351 * = (1 - white-x - white-y)/white-y 1352 * 1353 * In the last equation color-z is (1 - color-x - color-y) so we can add all 1354 * three equations together to get an alternative third: 1355 * 1356 * red-scale + green-scale + blue-scale = 1/white-y = white-scale 1357 * 1358 * So now we have a Cramer's rule solution where the determinants are just 1359 * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve 1360 * multiplication of three coefficients so we can't guarantee to avoid 1361 * overflow in the libpng fixed point representation. Using Cramer's rule in 1362 * floating point is probably a good choice here, but it's not an option for 1363 * fixed point. Instead proceed to simplify the first two equations by 1364 * eliminating what is likely to be the largest value, blue-scale: 1365 * 1366 * blue-scale = white-scale - red-scale - green-scale 1367 * 1368 * Hence: 1369 * 1370 * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale = 1371 * (white-x - blue-x)*white-scale 1372 * 1373 * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale = 1374 * 1 - blue-y*white-scale 1375 * 1376 * And now we can trivially solve for (red-scale,green-scale): 1377 * 1378 * green-scale = 1379 * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale 1380 * ----------------------------------------------------------- 1381 * green-x - blue-x 1382 * 1383 * red-scale = 1384 * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale 1385 * --------------------------------------------------------- 1386 * red-y - blue-y 1387 * 1388 * Hence: 1389 * 1390 * red-scale = 1391 * ( (green-x - blue-x) * (white-y - blue-y) - 1392 * (green-y - blue-y) * (white-x - blue-x) ) / white-y 1393 * ------------------------------------------------------------------------- 1394 * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x) 1395 * 1396 * green-scale = 1397 * ( (red-y - blue-y) * (white-x - blue-x) - 1398 * (red-x - blue-x) * (white-y - blue-y) ) / white-y 1399 * ------------------------------------------------------------------------- 1400 * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x) 1401 * 1402 * Accuracy: 1403 * The input values have 5 decimal digits of accuracy. The values are all in 1404 * the range 0 < value < 1, so simple products are in the same range but may 1405 * need up to 10 decimal digits to preserve the original precision and avoid 1406 * underflow. Because we are using a 32-bit signed representation we cannot 1407 * match this; the best is a little over 9 decimal digits, less than 10. 1408 * 1409 * The approach used here is to preserve the maximum precision within the 1410 * signed representation. Because the red-scale calculation above uses the 1411 * difference between two products of values that must be in the range -1..+1 1412 * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The 1413 * factor is irrelevant in the calculation because it is applied to both 1414 * numerator and denominator. 1415 * 1416 * Note that the values of the differences of the products of the 1417 * chromaticities in the above equations tend to be small, for example for 1418 * the sRGB chromaticities they are: 1419 * 1420 * red numerator: -0.04751 1421 * green numerator: -0.08788 1422 * denominator: -0.2241 (without white-y multiplication) 1423 * 1424 * The resultant Y coefficients from the chromaticities of some widely used 1425 * color space definitions are (to 15 decimal places): 1426 * 1427 * sRGB 1428 * 0.212639005871510 0.715168678767756 0.072192315360734 1429 * Kodak ProPhoto 1430 * 0.288071128229293 0.711843217810102 0.000085653960605 1431 * Adobe RGB 1432 * 0.297344975250536 0.627363566255466 0.075291458493998 1433 * Adobe Wide Gamut RGB 1434 * 0.258728243040113 0.724682314948566 0.016589442011321 1435 */ 1436 /* By the argument, above overflow should be impossible here. The return 1437 * value of 2 indicates an internal error to the caller. 1438 */ 1439 if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0) 1440 return 2; 1441 if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0) 1442 return 2; 1443 denominator = left - right; 1444 1445 /* Now find the red numerator. */ 1446 if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0) 1447 return 2; 1448 if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0) 1449 return 2; 1450 1451 /* Overflow is possible here and it indicates an extreme set of PNG cHRM 1452 * chunk values. This calculation actually returns the reciprocal of the 1453 * scale value because this allows us to delay the multiplication of white-y 1454 * into the denominator, which tends to produce a small number. 1455 */ 1456 if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 || 1457 red_inverse <= xy->whitey /* r+g+b scales = white scale */) 1458 return 1; 1459 1460 /* Similarly for green_inverse: */ 1461 if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0) 1462 return 2; 1463 if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0) 1464 return 2; 1465 if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 || 1466 green_inverse <= xy->whitey) 1467 return 1; 1468 1469 /* And the blue scale, the checks above guarantee this can't overflow but it 1470 * can still produce 0 for extreme cHRM values. 1471 */ 1472 blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) - 1473 png_reciprocal(green_inverse); 1474 if (blue_scale <= 0) 1475 return 1; 1476 1477 1478 /* And fill in the png_XYZ: */ 1479 if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0) 1480 return 1; 1481 if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0) 1482 return 1; 1483 if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1, 1484 red_inverse) == 0) 1485 return 1; 1486 1487 if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0) 1488 return 1; 1489 if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0) 1490 return 1; 1491 if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1, 1492 green_inverse) == 0) 1493 return 1; 1494 1495 if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0) 1496 return 1; 1497 if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0) 1498 return 1; 1499 if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale, 1500 PNG_FP_1) == 0) 1501 return 1; 1502 1503 return 0; /*success*/ 1504} 1505 1506static int 1507png_XYZ_normalize(png_XYZ *XYZ) 1508{ 1509 png_int_32 Y; 1510 1511 if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 || 1512 XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 || 1513 XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0) 1514 return 1; 1515 1516 /* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1. 1517 * IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore 1518 * relying on addition of two positive values producing a negative one is not 1519 * safe. 1520 */ 1521 Y = XYZ->red_Y; 1522 if (0x7fffffff - Y < XYZ->green_X) 1523 return 1; 1524 Y += XYZ->green_Y; 1525 if (0x7fffffff - Y < XYZ->blue_X) 1526 return 1; 1527 Y += XYZ->blue_Y; 1528 1529 if (Y != PNG_FP_1) 1530 { 1531 if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0) 1532 return 1; 1533 if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0) 1534 return 1; 1535 if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0) 1536 return 1; 1537 1538 if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0) 1539 return 1; 1540 if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0) 1541 return 1; 1542 if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0) 1543 return 1; 1544 1545 if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0) 1546 return 1; 1547 if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0) 1548 return 1; 1549 if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0) 1550 return 1; 1551 } 1552 1553 return 0; 1554} 1555 1556static int 1557png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta) 1558{ 1559 /* Allow an error of +/-0.01 (absolute value) on each chromaticity */ 1560 if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) || 1561 PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) || 1562 PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) || 1563 PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) || 1564 PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) || 1565 PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) || 1566 PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) || 1567 PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta)) 1568 return 0; 1569 return 1; 1570} 1571 1572/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM 1573 * chunk chromaticities. Earlier checks used to simply look for the overflow 1574 * condition (where the determinant of the matrix to solve for XYZ ends up zero 1575 * because the chromaticity values are not all distinct.) Despite this it is 1576 * theoretically possible to produce chromaticities that are apparently valid 1577 * but that rapidly degrade to invalid, potentially crashing, sets because of 1578 * arithmetic inaccuracies when calculations are performed on them. The new 1579 * check is to round-trip xy -> XYZ -> xy and then check that the result is 1580 * within a small percentage of the original. 1581 */ 1582static int 1583png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy) 1584{ 1585 int result; 1586 png_xy xy_test; 1587 1588 /* As a side-effect this routine also returns the XYZ endpoints. */ 1589 result = png_XYZ_from_xy(XYZ, xy); 1590 if (result != 0) 1591 return result; 1592 1593 result = png_xy_from_XYZ(&xy_test, XYZ); 1594 if (result != 0) 1595 return result; 1596 1597 if (png_colorspace_endpoints_match(xy, &xy_test, 1598 5/*actually, the math is pretty accurate*/) != 0) 1599 return 0; 1600 1601 /* Too much slip */ 1602 return 1; 1603} 1604 1605/* This is the check going the other way. The XYZ is modified to normalize it 1606 * (another side-effect) and the xy chromaticities are returned. 1607 */ 1608static int 1609png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ) 1610{ 1611 int result; 1612 png_XYZ XYZtemp; 1613 1614 result = png_XYZ_normalize(XYZ); 1615 if (result != 0) 1616 return result; 1617 1618 result = png_xy_from_XYZ(xy, XYZ); 1619 if (result != 0) 1620 return result; 1621 1622 XYZtemp = *XYZ; 1623 return png_colorspace_check_xy(&XYZtemp, xy); 1624} 1625 1626/* Used to check for an endpoint match against sRGB */ 1627static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */ 1628{ 1629 /* color x y */ 1630 /* red */ 64000, 33000, 1631 /* green */ 30000, 60000, 1632 /* blue */ 15000, 6000, 1633 /* white */ 31270, 32900 1634}; 1635 1636static int 1637png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr, 1638 png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ, 1639 int preferred) 1640{ 1641 if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0) 1642 return 0; 1643 1644 /* The consistency check is performed on the chromaticities; this factors out 1645 * variations because of the normalization (or not) of the end point Y 1646 * values. 1647 */ 1648 if (preferred < 2 && 1649 (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0) 1650 { 1651 /* The end points must be reasonably close to any we already have. The 1652 * following allows an error of up to +/-.001 1653 */ 1654 if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy, 1655 100) == 0) 1656 { 1657 colorspace->flags |= PNG_COLORSPACE_INVALID; 1658 png_benign_error(png_ptr, "inconsistent chromaticities"); 1659 return 0; /* failed */ 1660 } 1661 1662 /* Only overwrite with preferred values */ 1663 if (preferred == 0) 1664 return 1; /* ok, but no change */ 1665 } 1666 1667 colorspace->end_points_xy = *xy; 1668 colorspace->end_points_XYZ = *XYZ; 1669 colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS; 1670 1671 /* The end points are normally quoted to two decimal digits, so allow +/-0.01 1672 * on this test. 1673 */ 1674 if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0) 1675 colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB; 1676 1677 else 1678 colorspace->flags &= PNG_COLORSPACE_CANCEL( 1679 PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB); 1680 1681 return 2; /* ok and changed */ 1682} 1683 1684int /* PRIVATE */ 1685png_colorspace_set_chromaticities(png_const_structrp png_ptr, 1686 png_colorspacerp colorspace, const png_xy *xy, int preferred) 1687{ 1688 /* We must check the end points to ensure they are reasonable - in the past 1689 * color management systems have crashed as a result of getting bogus 1690 * colorant values, while this isn't the fault of libpng it is the 1691 * responsibility of libpng because PNG carries the bomb and libpng is in a 1692 * position to protect against it. 1693 */ 1694 png_XYZ XYZ; 1695 1696 switch (png_colorspace_check_xy(&XYZ, xy)) 1697 { 1698 case 0: /* success */ 1699 return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ, 1700 preferred); 1701 1702 case 1: 1703 /* We can't invert the chromaticities so we can't produce value XYZ 1704 * values. Likely as not a color management system will fail too. 1705 */ 1706 colorspace->flags |= PNG_COLORSPACE_INVALID; 1707 png_benign_error(png_ptr, "invalid chromaticities"); 1708 break; 1709 1710 default: 1711 /* libpng is broken; this should be a warning but if it happens we 1712 * want error reports so for the moment it is an error. 1713 */ 1714 colorspace->flags |= PNG_COLORSPACE_INVALID; 1715 png_error(png_ptr, "internal error checking chromaticities"); 1716 } 1717 1718 return 0; /* failed */ 1719} 1720 1721int /* PRIVATE */ 1722png_colorspace_set_endpoints(png_const_structrp png_ptr, 1723 png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred) 1724{ 1725 png_XYZ XYZ = *XYZ_in; 1726 png_xy xy; 1727 1728 switch (png_colorspace_check_XYZ(&xy, &XYZ)) 1729 { 1730 case 0: 1731 return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ, 1732 preferred); 1733 1734 case 1: 1735 /* End points are invalid. */ 1736 colorspace->flags |= PNG_COLORSPACE_INVALID; 1737 png_benign_error(png_ptr, "invalid end points"); 1738 break; 1739 1740 default: 1741 colorspace->flags |= PNG_COLORSPACE_INVALID; 1742 png_error(png_ptr, "internal error checking chromaticities"); 1743 } 1744 1745 return 0; /* failed */ 1746} 1747 1748#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED) 1749/* Error message generation */ 1750static char 1751png_icc_tag_char(png_uint_32 byte) 1752{ 1753 byte &= 0xff; 1754 if (byte >= 32 && byte <= 126) 1755 return (char)byte; 1756 else 1757 return '?'; 1758} 1759 1760static void 1761png_icc_tag_name(char *name, png_uint_32 tag) 1762{ 1763 name[0] = '\''; 1764 name[1] = png_icc_tag_char(tag >> 24); 1765 name[2] = png_icc_tag_char(tag >> 16); 1766 name[3] = png_icc_tag_char(tag >> 8); 1767 name[4] = png_icc_tag_char(tag ); 1768 name[5] = '\''; 1769} 1770 1771static int 1772is_ICC_signature_char(png_alloc_size_t it) 1773{ 1774 return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) || 1775 (it >= 97 && it <= 122); 1776} 1777 1778static int 1779is_ICC_signature(png_alloc_size_t it) 1780{ 1781 return is_ICC_signature_char(it >> 24) /* checks all the top bits */ && 1782 is_ICC_signature_char((it >> 16) & 0xff) && 1783 is_ICC_signature_char((it >> 8) & 0xff) && 1784 is_ICC_signature_char(it & 0xff); 1785} 1786 1787static int 1788png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace, 1789 png_const_charp name, png_alloc_size_t value, png_const_charp reason) 1790{ 1791 size_t pos; 1792 char message[196]; /* see below for calculation */ 1793 1794 if (colorspace != NULL) 1795 colorspace->flags |= PNG_COLORSPACE_INVALID; 1796 1797 pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */ 1798 pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */ 1799 pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */ 1800 if (is_ICC_signature(value) != 0) 1801 { 1802 /* So 'value' is at most 4 bytes and the following cast is safe */ 1803 png_icc_tag_name(message+pos, (png_uint_32)value); 1804 pos += 6; /* total +8; less than the else clause */ 1805 message[pos++] = ':'; 1806 message[pos++] = ' '; 1807 } 1808# ifdef PNG_WARNINGS_SUPPORTED 1809 else 1810 { 1811 char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/ 1812 1813 pos = png_safecat(message, (sizeof message), pos, 1814 png_format_number(number, number+(sizeof number), 1815 PNG_NUMBER_FORMAT_x, value)); 1816 pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/ 1817 } 1818# endif 1819 /* The 'reason' is an arbitrary message, allow +79 maximum 195 */ 1820 pos = png_safecat(message, (sizeof message), pos, reason); 1821 PNG_UNUSED(pos) 1822 1823 /* This is recoverable, but make it unconditionally an app_error on write to 1824 * avoid writing invalid ICC profiles into PNG files (i.e., we handle them 1825 * on read, with a warning, but on write unless the app turns off 1826 * application errors the PNG won't be written.) 1827 */ 1828 png_chunk_report(png_ptr, message, 1829 (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR); 1830 1831 return 0; 1832} 1833#endif /* sRGB || iCCP */ 1834 1835#ifdef PNG_sRGB_SUPPORTED 1836int /* PRIVATE */ 1837png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace, 1838 int intent) 1839{ 1840 /* sRGB sets known gamma, end points and (from the chunk) intent. */ 1841 /* IMPORTANT: these are not necessarily the values found in an ICC profile 1842 * because ICC profiles store values adapted to a D50 environment; it is 1843 * expected that the ICC profile mediaWhitePointTag will be D50; see the 1844 * checks and code elsewhere to understand this better. 1845 * 1846 * These XYZ values, which are accurate to 5dp, produce rgb to gray 1847 * coefficients of (6968,23435,2366), which are reduced (because they add up 1848 * to 32769 not 32768) to (6968,23434,2366). These are the values that 1849 * libpng has traditionally used (and are the best values given the 15bit 1850 * algorithm used by the rgb to gray code.) 1851 */ 1852 static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */ 1853 { 1854 /* color X Y Z */ 1855 /* red */ 41239, 21264, 1933, 1856 /* green */ 35758, 71517, 11919, 1857 /* blue */ 18048, 7219, 95053 1858 }; 1859 1860 /* Do nothing if the colorspace is already invalidated. */ 1861 if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0) 1862 return 0; 1863 1864 /* Check the intent, then check for existing settings. It is valid for the 1865 * PNG file to have cHRM or gAMA chunks along with sRGB, but the values must 1866 * be consistent with the correct values. If, however, this function is 1867 * called below because an iCCP chunk matches sRGB then it is quite 1868 * conceivable that an older app recorded incorrect gAMA and cHRM because of 1869 * an incorrect calculation based on the values in the profile - this does 1870 * *not* invalidate the profile (though it still produces an error, which can 1871 * be ignored.) 1872 */ 1873 if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST) 1874 return png_icc_profile_error(png_ptr, colorspace, "sRGB", 1875 (unsigned)intent, "invalid sRGB rendering intent"); 1876 1877 if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 && 1878 colorspace->rendering_intent != intent) 1879 return png_icc_profile_error(png_ptr, colorspace, "sRGB", 1880 (unsigned)intent, "inconsistent rendering intents"); 1881 1882 if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0) 1883 { 1884 png_benign_error(png_ptr, "duplicate sRGB information ignored"); 1885 return 0; 1886 } 1887 1888 /* If the standard sRGB cHRM chunk does not match the one from the PNG file 1889 * warn but overwrite the value with the correct one. 1890 */ 1891 if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 && 1892 !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy, 1893 100)) 1894 png_chunk_report(png_ptr, "cHRM chunk does not match sRGB", 1895 PNG_CHUNK_ERROR); 1896 1897 /* This check is just done for the error reporting - the routine always 1898 * returns true when the 'from' argument corresponds to sRGB (2). 1899 */ 1900 (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE, 1901 2/*from sRGB*/); 1902 1903 /* intent: bugs in GCC force 'int' to be used as the parameter type. */ 1904 colorspace->rendering_intent = (png_uint_16)intent; 1905 colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT; 1906 1907 /* endpoints */ 1908 colorspace->end_points_xy = sRGB_xy; 1909 colorspace->end_points_XYZ = sRGB_XYZ; 1910 colorspace->flags |= 1911 (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB); 1912 1913 /* gamma */ 1914 colorspace->gamma = PNG_GAMMA_sRGB_INVERSE; 1915 colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA; 1916 1917 /* Finally record that we have an sRGB profile */ 1918 colorspace->flags |= 1919 (PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB); 1920 1921 return 1; /* set */ 1922} 1923#endif /* sRGB */ 1924 1925#ifdef PNG_iCCP_SUPPORTED 1926/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value 1927 * is XYZ(0.9642,1.0,0.8249), which scales to: 1928 * 1929 * (63189.8112, 65536, 54060.6464) 1930 */ 1931static const png_byte D50_nCIEXYZ[12] = 1932 { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d }; 1933 1934int /* PRIVATE */ 1935png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace, 1936 png_const_charp name, png_uint_32 profile_length) 1937{ 1938 if (profile_length < 132) 1939 return png_icc_profile_error(png_ptr, colorspace, name, profile_length, 1940 "too short"); 1941 1942 return 1; 1943} 1944 1945int /* PRIVATE */ 1946png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace, 1947 png_const_charp name, png_uint_32 profile_length, 1948 png_const_bytep profile/* first 132 bytes only */, int color_type) 1949{ 1950 png_uint_32 temp; 1951 1952 /* Length check; this cannot be ignored in this code because profile_length 1953 * is used later to check the tag table, so even if the profile seems over 1954 * long profile_length from the caller must be correct. The caller can fix 1955 * this up on read or write by just passing in the profile header length. 1956 */ 1957 temp = png_get_uint_32(profile); 1958 if (temp != profile_length) 1959 return png_icc_profile_error(png_ptr, colorspace, name, temp, 1960 "length does not match profile"); 1961 1962 temp = (png_uint_32) (*(profile+8)); 1963 if (temp > 3 && (profile_length & 3)) 1964 return png_icc_profile_error(png_ptr, colorspace, name, profile_length, 1965 "invalid length"); 1966 1967 temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */ 1968 if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */ 1969 profile_length < 132+12*temp) /* truncated tag table */ 1970 return png_icc_profile_error(png_ptr, colorspace, name, temp, 1971 "tag count too large"); 1972 1973 /* The 'intent' must be valid or we can't store it, ICC limits the intent to 1974 * 16 bits. 1975 */ 1976 temp = png_get_uint_32(profile+64); 1977 if (temp >= 0xffff) /* The ICC limit */ 1978 return png_icc_profile_error(png_ptr, colorspace, name, temp, 1979 "invalid rendering intent"); 1980 1981 /* This is just a warning because the profile may be valid in future 1982 * versions. 1983 */ 1984 if (temp >= PNG_sRGB_INTENT_LAST) 1985 (void)png_icc_profile_error(png_ptr, NULL, name, temp, 1986 "intent outside defined range"); 1987 1988 /* At this point the tag table can't be checked because it hasn't necessarily 1989 * been loaded; however, various header fields can be checked. These checks 1990 * are for values permitted by the PNG spec in an ICC profile; the PNG spec 1991 * restricts the profiles that can be passed in an iCCP chunk (they must be 1992 * appropriate to processing PNG data!) 1993 */ 1994 1995 /* Data checks (could be skipped). These checks must be independent of the 1996 * version number; however, the version number doesn't accomodate changes in 1997 * the header fields (just the known tags and the interpretation of the 1998 * data.) 1999 */ 2000 temp = png_get_uint_32(profile+36); /* signature 'ascp' */ 2001 if (temp != 0x61637370) 2002 return png_icc_profile_error(png_ptr, colorspace, name, temp, 2003 "invalid signature"); 2004 2005 /* Currently the PCS illuminant/adopted white point (the computational 2006 * white point) are required to be D50, 2007 * however the profile contains a record of the illuminant so perhaps ICC 2008 * expects to be able to change this in the future (despite the rationale in 2009 * the introduction for using a fixed PCS adopted white.) Consequently the 2010 * following is just a warning. 2011 */ 2012 if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0) 2013 (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/, 2014 "PCS illuminant is not D50"); 2015 2016 /* The PNG spec requires this: 2017 * "If the iCCP chunk is present, the image samples conform to the colour 2018 * space represented by the embedded ICC profile as defined by the 2019 * International Color Consortium [ICC]. The colour space of the ICC profile 2020 * shall be an RGB colour space for colour images (PNG colour types 2, 3, and 2021 * 6), or a greyscale colour space for greyscale images (PNG colour types 0 2022 * and 4)." 2023 * 2024 * This checking code ensures the embedded profile (on either read or write) 2025 * conforms to the specification requirements. Notice that an ICC 'gray' 2026 * color-space profile contains the information to transform the monochrome 2027 * data to XYZ or L*a*b (according to which PCS the profile uses) and this 2028 * should be used in preference to the standard libpng K channel replication 2029 * into R, G and B channels. 2030 * 2031 * Previously it was suggested that an RGB profile on grayscale data could be 2032 * handled. However it it is clear that using an RGB profile in this context 2033 * must be an error - there is no specification of what it means. Thus it is 2034 * almost certainly more correct to ignore the profile. 2035 */ 2036 temp = png_get_uint_32(profile+16); /* data colour space field */ 2037 switch (temp) 2038 { 2039 case 0x52474220: /* 'RGB ' */ 2040 if ((color_type & PNG_COLOR_MASK_COLOR) == 0) 2041 return png_icc_profile_error(png_ptr, colorspace, name, temp, 2042 "RGB color space not permitted on grayscale PNG"); 2043 break; 2044 2045 case 0x47524159: /* 'GRAY' */ 2046 if ((color_type & PNG_COLOR_MASK_COLOR) != 0) 2047 return png_icc_profile_error(png_ptr, colorspace, name, temp, 2048 "Gray color space not permitted on RGB PNG"); 2049 break; 2050 2051 default: 2052 return png_icc_profile_error(png_ptr, colorspace, name, temp, 2053 "invalid ICC profile color space"); 2054 } 2055 2056 /* It is up to the application to check that the profile class matches the 2057 * application requirements; the spec provides no guidance, but it's pretty 2058 * weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer 2059 * ('prtr') or 'spac' (for generic color spaces). Issue a warning in these 2060 * cases. Issue an error for device link or abstract profiles - these don't 2061 * contain the records necessary to transform the color-space to anything 2062 * other than the target device (and not even that for an abstract profile). 2063 * Profiles of these classes may not be embedded in images. 2064 */ 2065 temp = png_get_uint_32(profile+12); /* profile/device class */ 2066 switch (temp) 2067 { 2068 case 0x73636e72: /* 'scnr' */ 2069 case 0x6d6e7472: /* 'mntr' */ 2070 case 0x70727472: /* 'prtr' */ 2071 case 0x73706163: /* 'spac' */ 2072 /* All supported */ 2073 break; 2074 2075 case 0x61627374: /* 'abst' */ 2076 /* May not be embedded in an image */ 2077 return png_icc_profile_error(png_ptr, colorspace, name, temp, 2078 "invalid embedded Abstract ICC profile"); 2079 2080 case 0x6c696e6b: /* 'link' */ 2081 /* DeviceLink profiles cannot be interpreted in a non-device specific 2082 * fashion, if an app uses the AToB0Tag in the profile the results are 2083 * undefined unless the result is sent to the intended device, 2084 * therefore a DeviceLink profile should not be found embedded in a 2085 * PNG. 2086 */ 2087 return png_icc_profile_error(png_ptr, colorspace, name, temp, 2088 "unexpected DeviceLink ICC profile class"); 2089 2090 case 0x6e6d636c: /* 'nmcl' */ 2091 /* A NamedColor profile is also device specific, however it doesn't 2092 * contain an AToB0 tag that is open to misinterpretation. Almost 2093 * certainly it will fail the tests below. 2094 */ 2095 (void)png_icc_profile_error(png_ptr, NULL, name, temp, 2096 "unexpected NamedColor ICC profile class"); 2097 break; 2098 2099 default: 2100 /* To allow for future enhancements to the profile accept unrecognized 2101 * profile classes with a warning, these then hit the test below on the 2102 * tag content to ensure they are backward compatible with one of the 2103 * understood profiles. 2104 */ 2105 (void)png_icc_profile_error(png_ptr, NULL, name, temp, 2106 "unrecognized ICC profile class"); 2107 break; 2108 } 2109 2110 /* For any profile other than a device link one the PCS must be encoded 2111 * either in XYZ or Lab. 2112 */ 2113 temp = png_get_uint_32(profile+20); 2114 switch (temp) 2115 { 2116 case 0x58595a20: /* 'XYZ ' */ 2117 case 0x4c616220: /* 'Lab ' */ 2118 break; 2119 2120 default: 2121 return png_icc_profile_error(png_ptr, colorspace, name, temp, 2122 "unexpected ICC PCS encoding"); 2123 } 2124 2125 return 1; 2126} 2127 2128int /* PRIVATE */ 2129png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace, 2130 png_const_charp name, png_uint_32 profile_length, 2131 png_const_bytep profile /* header plus whole tag table */) 2132{ 2133 png_uint_32 tag_count = png_get_uint_32(profile+128); 2134 png_uint_32 itag; 2135 png_const_bytep tag = profile+132; /* The first tag */ 2136 2137 /* First scan all the tags in the table and add bits to the icc_info value 2138 * (temporarily in 'tags'). 2139 */ 2140 for (itag=0; itag < tag_count; ++itag, tag += 12) 2141 { 2142 png_uint_32 tag_id = png_get_uint_32(tag+0); 2143 png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */ 2144 png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */ 2145 2146 /* The ICC specification does not exclude zero length tags, therefore the 2147 * start might actually be anywhere if there is no data, but this would be 2148 * a clear abuse of the intent of the standard so the start is checked for 2149 * being in range. All defined tag types have an 8 byte header - a 4 byte 2150 * type signature then 0. 2151 */ 2152 if ((tag_start & 3) != 0) 2153 { 2154 /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is 2155 * only a warning here because libpng does not care about the 2156 * alignment. 2157 */ 2158 (void)png_icc_profile_error(png_ptr, NULL, name, tag_id, 2159 "ICC profile tag start not a multiple of 4"); 2160 } 2161 2162 /* This is a hard error; potentially it can cause read outside the 2163 * profile. 2164 */ 2165 if (tag_start > profile_length || tag_length > profile_length - tag_start) 2166 return png_icc_profile_error(png_ptr, colorspace, name, tag_id, 2167 "ICC profile tag outside profile"); 2168 } 2169 2170 return 1; /* success, maybe with warnings */ 2171} 2172 2173#ifdef PNG_sRGB_SUPPORTED 2174#if PNG_sRGB_PROFILE_CHECKS >= 0 2175/* Information about the known ICC sRGB profiles */ 2176static const struct 2177{ 2178 png_uint_32 adler, crc, length; 2179 png_uint_32 md5[4]; 2180 png_byte have_md5; 2181 png_byte is_broken; 2182 png_uint_16 intent; 2183 2184# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0) 2185# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\ 2186 { adler, crc, length, md5, broke, intent }, 2187 2188} png_sRGB_checks[] = 2189{ 2190 /* This data comes from contrib/tools/checksum-icc run on downloads of 2191 * all four ICC sRGB profiles from www.color.org. 2192 */ 2193 /* adler32, crc32, MD5[4], intent, date, length, file-name */ 2194 PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9, 2195 PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0, 2196 "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc") 2197 2198 /* ICC sRGB v2 perceptual no black-compensation: */ 2199 PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21, 2200 PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0, 2201 "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc") 2202 2203 PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae, 2204 PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0, 2205 "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc") 2206 2207 /* ICC sRGB v4 perceptual */ 2208 PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812, 2209 PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0, 2210 "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc") 2211 2212 /* The following profiles have no known MD5 checksum. If there is a match 2213 * on the (empty) MD5 the other fields are used to attempt a match and 2214 * a warning is produced. The first two of these profiles have a 'cprt' tag 2215 * which suggests that they were also made by Hewlett Packard. 2216 */ 2217 PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce, 2218 PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0, 2219 "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc") 2220 2221 /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not 2222 * match the D50 PCS illuminant in the header (it is in fact the D65 values, 2223 * so the white point is recorded as the un-adapted value.) The profiles 2224 * below only differ in one byte - the intent - and are basically the same as 2225 * the previous profile except for the mediaWhitePointTag error and a missing 2226 * chromaticAdaptationTag. 2227 */ 2228 PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552, 2229 PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/, 2230 "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual") 2231 2232 PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d, 2233 PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/, 2234 "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative") 2235}; 2236 2237static int 2238png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr, 2239 png_const_bytep profile, uLong adler) 2240{ 2241 /* The quick check is to verify just the MD5 signature and trust the 2242 * rest of the data. Because the profile has already been verified for 2243 * correctness this is safe. png_colorspace_set_sRGB will check the 'intent' 2244 * field too, so if the profile has been edited with an intent not defined 2245 * by sRGB (but maybe defined by a later ICC specification) the read of 2246 * the profile will fail at that point. 2247 */ 2248 2249 png_uint_32 length = 0; 2250 png_uint_32 intent = 0x10000; /* invalid */ 2251#if PNG_sRGB_PROFILE_CHECKS > 1 2252 uLong crc = 0; /* the value for 0 length data */ 2253#endif 2254 unsigned int i; 2255 2256#ifdef PNG_SET_OPTION_SUPPORTED 2257 /* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */ 2258 if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) == 2259 PNG_OPTION_ON) 2260 return 0; 2261#endif 2262 2263 for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i) 2264 { 2265 if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] && 2266 png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] && 2267 png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] && 2268 png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3]) 2269 { 2270 /* This may be one of the old HP profiles without an MD5, in that 2271 * case we can only use the length and Adler32 (note that these 2272 * are not used by default if there is an MD5!) 2273 */ 2274# if PNG_sRGB_PROFILE_CHECKS == 0 2275 if (png_sRGB_checks[i].have_md5 != 0) 2276 return 1+png_sRGB_checks[i].is_broken; 2277# endif 2278 2279 /* Profile is unsigned or more checks have been configured in. */ 2280 if (length == 0) 2281 { 2282 length = png_get_uint_32(profile); 2283 intent = png_get_uint_32(profile+64); 2284 } 2285 2286 /* Length *and* intent must match */ 2287 if (length == (png_uint_32) png_sRGB_checks[i].length && 2288 intent == (png_uint_32) png_sRGB_checks[i].intent) 2289 { 2290 /* Now calculate the adler32 if not done already. */ 2291 if (adler == 0) 2292 { 2293 adler = adler32(0, NULL, 0); 2294 adler = adler32(adler, profile, length); 2295 } 2296 2297 if (adler == png_sRGB_checks[i].adler) 2298 { 2299 /* These basic checks suggest that the data has not been 2300 * modified, but if the check level is more than 1 perform 2301 * our own crc32 checksum on the data. 2302 */ 2303# if PNG_sRGB_PROFILE_CHECKS > 1 2304 if (crc == 0) 2305 { 2306 crc = crc32(0, NULL, 0); 2307 crc = crc32(crc, profile, length); 2308 } 2309 2310 /* So this check must pass for the 'return' below to happen. 2311 */ 2312 if (crc == png_sRGB_checks[i].crc) 2313# endif 2314 { 2315 if (png_sRGB_checks[i].is_broken != 0) 2316 { 2317 /* These profiles are known to have bad data that may cause 2318 * problems if they are used, therefore attempt to 2319 * discourage their use, skip the 'have_md5' warning below, 2320 * which is made irrelevant by this error. 2321 */ 2322 png_chunk_report(png_ptr, "known incorrect sRGB profile", 2323 PNG_CHUNK_ERROR); 2324 } 2325 2326 /* Warn that this being done; this isn't even an error since 2327 * the profile is perfectly valid, but it would be nice if 2328 * people used the up-to-date ones. 2329 */ 2330 else if (png_sRGB_checks[i].have_md5 == 0) 2331 { 2332 png_chunk_report(png_ptr, 2333 "out-of-date sRGB profile with no signature", 2334 PNG_CHUNK_WARNING); 2335 } 2336 2337 return 1+png_sRGB_checks[i].is_broken; 2338 } 2339 } 2340 2341# if PNG_sRGB_PROFILE_CHECKS > 0 2342 /* The signature matched, but the profile had been changed in some 2343 * way. This probably indicates a data error or uninformed hacking. 2344 * Fall through to "no match". 2345 */ 2346 png_chunk_report(png_ptr, 2347 "Not recognizing known sRGB profile that has been edited", 2348 PNG_CHUNK_WARNING); 2349 break; 2350# endif 2351 } 2352 } 2353 } 2354 2355 return 0; /* no match */ 2356} 2357#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */ 2358 2359void /* PRIVATE */ 2360png_icc_set_sRGB(png_const_structrp png_ptr, 2361 png_colorspacerp colorspace, png_const_bytep profile, uLong adler) 2362{ 2363 /* Is this profile one of the known ICC sRGB profiles? If it is, just set 2364 * the sRGB information. 2365 */ 2366#if PNG_sRGB_PROFILE_CHECKS >= 0 2367 if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0) 2368#endif 2369 (void)png_colorspace_set_sRGB(png_ptr, colorspace, 2370 (int)/*already checked*/png_get_uint_32(profile+64)); 2371} 2372#endif /* sRGB */ 2373 2374int /* PRIVATE */ 2375png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace, 2376 png_const_charp name, png_uint_32 profile_length, png_const_bytep profile, 2377 int color_type) 2378{ 2379 if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0) 2380 return 0; 2381 2382 if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 && 2383 png_icc_check_header(png_ptr, colorspace, name, profile_length, profile, 2384 color_type) != 0 && 2385 png_icc_check_tag_table(png_ptr, colorspace, name, profile_length, 2386 profile) != 0) 2387 { 2388# ifdef PNG_sRGB_SUPPORTED 2389 /* If no sRGB support, don't try storing sRGB information */ 2390 png_icc_set_sRGB(png_ptr, colorspace, profile, 0); 2391# endif 2392 return 1; 2393 } 2394 2395 /* Failure case */ 2396 return 0; 2397} 2398#endif /* iCCP */ 2399 2400#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED 2401void /* PRIVATE */ 2402png_colorspace_set_rgb_coefficients(png_structrp png_ptr) 2403{ 2404 /* Set the rgb_to_gray coefficients from the colorspace. */ 2405 if (png_ptr->rgb_to_gray_coefficients_set == 0 && 2406 (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0) 2407 { 2408 /* png_set_background has not been called, get the coefficients from the Y 2409 * values of the colorspace colorants. 2410 */ 2411 png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y; 2412 png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y; 2413 png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y; 2414 png_fixed_point total = r+g+b; 2415 2416 if (total > 0 && 2417 r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 && 2418 g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 && 2419 b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 && 2420 r+g+b <= 32769) 2421 { 2422 /* We allow 0 coefficients here. r+g+b may be 32769 if two or 2423 * all of the coefficients were rounded up. Handle this by 2424 * reducing the *largest* coefficient by 1; this matches the 2425 * approach used for the default coefficients in pngrtran.c 2426 */ 2427 int add = 0; 2428 2429 if (r+g+b > 32768) 2430 add = -1; 2431 else if (r+g+b < 32768) 2432 add = 1; 2433 2434 if (add != 0) 2435 { 2436 if (g >= r && g >= b) 2437 g += add; 2438 else if (r >= g && r >= b) 2439 r += add; 2440 else 2441 b += add; 2442 } 2443 2444 /* Check for an internal error. */ 2445 if (r+g+b != 32768) 2446 png_error(png_ptr, 2447 "internal error handling cHRM coefficients"); 2448 2449 else 2450 { 2451 png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r; 2452 png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g; 2453 } 2454 } 2455 2456 /* This is a png_error at present even though it could be ignored - 2457 * it should never happen, but it is important that if it does, the 2458 * bug is fixed. 2459 */ 2460 else 2461 png_error(png_ptr, "internal error handling cHRM->XYZ"); 2462 } 2463} 2464#endif /* READ_RGB_TO_GRAY */ 2465 2466#endif /* COLORSPACE */ 2467 2468#ifdef __GNUC__ 2469/* This exists solely to work round a warning from GNU C. */ 2470static int /* PRIVATE */ 2471png_gt(size_t a, size_t b) 2472{ 2473 return a > b; 2474} 2475#else 2476# define png_gt(a,b) ((a) > (b)) 2477#endif 2478 2479void /* PRIVATE */ 2480png_check_IHDR(png_const_structrp png_ptr, 2481 png_uint_32 width, png_uint_32 height, int bit_depth, 2482 int color_type, int interlace_type, int compression_type, 2483 int filter_type) 2484{ 2485 int error = 0; 2486 2487 /* Check for width and height valid values */ 2488 if (width == 0) 2489 { 2490 png_warning(png_ptr, "Image width is zero in IHDR"); 2491 error = 1; 2492 } 2493 2494 if (width > PNG_UINT_31_MAX) 2495 { 2496 png_warning(png_ptr, "Invalid image width in IHDR"); 2497 error = 1; 2498 } 2499 2500 if (png_gt(((width + 7) & (~7)), 2501 ((PNG_SIZE_MAX 2502 - 48 /* big_row_buf hack */ 2503 - 1) /* filter byte */ 2504 / 8) /* 8-byte RGBA pixels */ 2505 - 1)) /* extra max_pixel_depth pad */ 2506 { 2507 /* The size of the row must be within the limits of this architecture. 2508 * Because the read code can perform arbitrary transformations the 2509 * maximum size is checked here. Because the code in png_read_start_row 2510 * adds extra space "for safety's sake" in several places a conservative 2511 * limit is used here. 2512 * 2513 * NOTE: it would be far better to check the size that is actually used, 2514 * but the effect in the real world is minor and the changes are more 2515 * extensive, therefore much more dangerous and much more difficult to 2516 * write in a way that avoids compiler warnings. 2517 */ 2518 png_warning(png_ptr, "Image width is too large for this architecture"); 2519 error = 1; 2520 } 2521 2522#ifdef PNG_SET_USER_LIMITS_SUPPORTED 2523 if (width > png_ptr->user_width_max) 2524#else 2525 if (width > PNG_USER_WIDTH_MAX) 2526#endif 2527 { 2528 png_warning(png_ptr, "Image width exceeds user limit in IHDR"); 2529 error = 1; 2530 } 2531 2532 if (height == 0) 2533 { 2534 png_warning(png_ptr, "Image height is zero in IHDR"); 2535 error = 1; 2536 } 2537 2538 if (height > PNG_UINT_31_MAX) 2539 { 2540 png_warning(png_ptr, "Invalid image height in IHDR"); 2541 error = 1; 2542 } 2543 2544#ifdef PNG_SET_USER_LIMITS_SUPPORTED 2545 if (height > png_ptr->user_height_max) 2546#else 2547 if (height > PNG_USER_HEIGHT_MAX) 2548#endif 2549 { 2550 png_warning(png_ptr, "Image height exceeds user limit in IHDR"); 2551 error = 1; 2552 } 2553 2554 /* Check other values */ 2555 if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 && 2556 bit_depth != 8 && bit_depth != 16) 2557 { 2558 png_warning(png_ptr, "Invalid bit depth in IHDR"); 2559 error = 1; 2560 } 2561 2562 if (color_type < 0 || color_type == 1 || 2563 color_type == 5 || color_type > 6) 2564 { 2565 png_warning(png_ptr, "Invalid color type in IHDR"); 2566 error = 1; 2567 } 2568 2569 if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) || 2570 ((color_type == PNG_COLOR_TYPE_RGB || 2571 color_type == PNG_COLOR_TYPE_GRAY_ALPHA || 2572 color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8)) 2573 { 2574 png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR"); 2575 error = 1; 2576 } 2577 2578 if (interlace_type >= PNG_INTERLACE_LAST) 2579 { 2580 png_warning(png_ptr, "Unknown interlace method in IHDR"); 2581 error = 1; 2582 } 2583 2584 if (compression_type != PNG_COMPRESSION_TYPE_BASE) 2585 { 2586 png_warning(png_ptr, "Unknown compression method in IHDR"); 2587 error = 1; 2588 } 2589 2590#ifdef PNG_MNG_FEATURES_SUPPORTED 2591 /* Accept filter_method 64 (intrapixel differencing) only if 2592 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and 2593 * 2. Libpng did not read a PNG signature (this filter_method is only 2594 * used in PNG datastreams that are embedded in MNG datastreams) and 2595 * 3. The application called png_permit_mng_features with a mask that 2596 * included PNG_FLAG_MNG_FILTER_64 and 2597 * 4. The filter_method is 64 and 2598 * 5. The color_type is RGB or RGBA 2599 */ 2600 if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 && 2601 png_ptr->mng_features_permitted != 0) 2602 png_warning(png_ptr, "MNG features are not allowed in a PNG datastream"); 2603 2604 if (filter_type != PNG_FILTER_TYPE_BASE) 2605 { 2606 if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && 2607 (filter_type == PNG_INTRAPIXEL_DIFFERENCING) && 2608 ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && 2609 (color_type == PNG_COLOR_TYPE_RGB || 2610 color_type == PNG_COLOR_TYPE_RGB_ALPHA))) 2611 { 2612 png_warning(png_ptr, "Unknown filter method in IHDR"); 2613 error = 1; 2614 } 2615 2616 if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0) 2617 { 2618 png_warning(png_ptr, "Invalid filter method in IHDR"); 2619 error = 1; 2620 } 2621 } 2622 2623#else 2624 if (filter_type != PNG_FILTER_TYPE_BASE) 2625 { 2626 png_warning(png_ptr, "Unknown filter method in IHDR"); 2627 error = 1; 2628 } 2629#endif 2630 2631 if (error == 1) 2632 png_error(png_ptr, "Invalid IHDR data"); 2633} 2634 2635#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED) 2636/* ASCII to fp functions */ 2637/* Check an ASCII formated floating point value, see the more detailed 2638 * comments in pngpriv.h 2639 */ 2640/* The following is used internally to preserve the sticky flags */ 2641#define png_fp_add(state, flags) ((state) |= (flags)) 2642#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY)) 2643 2644int /* PRIVATE */ 2645png_check_fp_number(png_const_charp string, png_size_t size, int *statep, 2646 png_size_tp whereami) 2647{ 2648 int state = *statep; 2649 png_size_t i = *whereami; 2650 2651 while (i < size) 2652 { 2653 int type; 2654 /* First find the type of the next character */ 2655 switch (string[i]) 2656 { 2657 case 43: type = PNG_FP_SAW_SIGN; break; 2658 case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break; 2659 case 46: type = PNG_FP_SAW_DOT; break; 2660 case 48: type = PNG_FP_SAW_DIGIT; break; 2661 case 49: case 50: case 51: case 52: 2662 case 53: case 54: case 55: case 56: 2663 case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break; 2664 case 69: 2665 case 101: type = PNG_FP_SAW_E; break; 2666 default: goto PNG_FP_End; 2667 } 2668 2669 /* Now deal with this type according to the current 2670 * state, the type is arranged to not overlap the 2671 * bits of the PNG_FP_STATE. 2672 */ 2673 switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY)) 2674 { 2675 case PNG_FP_INTEGER + PNG_FP_SAW_SIGN: 2676 if ((state & PNG_FP_SAW_ANY) != 0) 2677 goto PNG_FP_End; /* not a part of the number */ 2678 2679 png_fp_add(state, type); 2680 break; 2681 2682 case PNG_FP_INTEGER + PNG_FP_SAW_DOT: 2683 /* Ok as trailer, ok as lead of fraction. */ 2684 if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */ 2685 goto PNG_FP_End; 2686 2687 else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */ 2688 png_fp_add(state, type); 2689 2690 else 2691 png_fp_set(state, PNG_FP_FRACTION | type); 2692 2693 break; 2694 2695 case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT: 2696 if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */ 2697 png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT); 2698 2699 png_fp_add(state, type | PNG_FP_WAS_VALID); 2700 2701 break; 2702 2703 case PNG_FP_INTEGER + PNG_FP_SAW_E: 2704 if ((state & PNG_FP_SAW_DIGIT) == 0) 2705 goto PNG_FP_End; 2706 2707 png_fp_set(state, PNG_FP_EXPONENT); 2708 2709 break; 2710 2711 /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN: 2712 goto PNG_FP_End; ** no sign in fraction */ 2713 2714 /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT: 2715 goto PNG_FP_End; ** Because SAW_DOT is always set */ 2716 2717 case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT: 2718 png_fp_add(state, type | PNG_FP_WAS_VALID); 2719 break; 2720 2721 case PNG_FP_FRACTION + PNG_FP_SAW_E: 2722 /* This is correct because the trailing '.' on an 2723 * integer is handled above - so we can only get here 2724 * with the sequence ".E" (with no preceding digits). 2725 */ 2726 if ((state & PNG_FP_SAW_DIGIT) == 0) 2727 goto PNG_FP_End; 2728 2729 png_fp_set(state, PNG_FP_EXPONENT); 2730 2731 break; 2732 2733 case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN: 2734 if ((state & PNG_FP_SAW_ANY) != 0) 2735 goto PNG_FP_End; /* not a part of the number */ 2736 2737 png_fp_add(state, PNG_FP_SAW_SIGN); 2738 2739 break; 2740 2741 /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT: 2742 goto PNG_FP_End; */ 2743 2744 case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT: 2745 png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID); 2746 2747 break; 2748 2749 /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E: 2750 goto PNG_FP_End; */ 2751 2752 default: goto PNG_FP_End; /* I.e. break 2 */ 2753 } 2754 2755 /* The character seems ok, continue. */ 2756 ++i; 2757 } 2758 2759PNG_FP_End: 2760 /* Here at the end, update the state and return the correct 2761 * return code. 2762 */ 2763 *statep = state; 2764 *whereami = i; 2765 2766 return (state & PNG_FP_SAW_DIGIT) != 0; 2767} 2768 2769 2770/* The same but for a complete string. */ 2771int 2772png_check_fp_string(png_const_charp string, png_size_t size) 2773{ 2774 int state=0; 2775 png_size_t char_index=0; 2776 2777 if (png_check_fp_number(string, size, &state, &char_index) != 0 && 2778 (char_index == size || string[char_index] == 0)) 2779 return state /* must be non-zero - see above */; 2780 2781 return 0; /* i.e. fail */ 2782} 2783#endif /* pCAL || sCAL */ 2784 2785#ifdef PNG_sCAL_SUPPORTED 2786# ifdef PNG_FLOATING_POINT_SUPPORTED 2787/* Utility used below - a simple accurate power of ten from an integral 2788 * exponent. 2789 */ 2790static double 2791png_pow10(int power) 2792{ 2793 int recip = 0; 2794 double d = 1; 2795 2796 /* Handle negative exponent with a reciprocal at the end because 2797 * 10 is exact whereas .1 is inexact in base 2 2798 */ 2799 if (power < 0) 2800 { 2801 if (power < DBL_MIN_10_EXP) return 0; 2802 recip = 1, power = -power; 2803 } 2804 2805 if (power > 0) 2806 { 2807 /* Decompose power bitwise. */ 2808 double mult = 10; 2809 do 2810 { 2811 if (power & 1) d *= mult; 2812 mult *= mult; 2813 power >>= 1; 2814 } 2815 while (power > 0); 2816 2817 if (recip != 0) d = 1/d; 2818 } 2819 /* else power is 0 and d is 1 */ 2820 2821 return d; 2822} 2823 2824/* Function to format a floating point value in ASCII with a given 2825 * precision. 2826 */ 2827void /* PRIVATE */ 2828png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size, 2829 double fp, unsigned int precision) 2830{ 2831 /* We use standard functions from math.h, but not printf because 2832 * that would require stdio. The caller must supply a buffer of 2833 * sufficient size or we will png_error. The tests on size and 2834 * the space in ascii[] consumed are indicated below. 2835 */ 2836 if (precision < 1) 2837 precision = DBL_DIG; 2838 2839 /* Enforce the limit of the implementation precision too. */ 2840 if (precision > DBL_DIG+1) 2841 precision = DBL_DIG+1; 2842 2843 /* Basic sanity checks */ 2844 if (size >= precision+5) /* See the requirements below. */ 2845 { 2846 if (fp < 0) 2847 { 2848 fp = -fp; 2849 *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */ 2850 --size; 2851 } 2852 2853 if (fp >= DBL_MIN && fp <= DBL_MAX) 2854 { 2855 int exp_b10; /* A base 10 exponent */ 2856 double base; /* 10^exp_b10 */ 2857 2858 /* First extract a base 10 exponent of the number, 2859 * the calculation below rounds down when converting 2860 * from base 2 to base 10 (multiply by log10(2) - 2861 * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to 2862 * be increased. Note that the arithmetic shift 2863 * performs a floor() unlike C arithmetic - using a 2864 * C multiply would break the following for negative 2865 * exponents. 2866 */ 2867 (void)frexp(fp, &exp_b10); /* exponent to base 2 */ 2868 2869 exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */ 2870 2871 /* Avoid underflow here. */ 2872 base = png_pow10(exp_b10); /* May underflow */ 2873 2874 while (base < DBL_MIN || base < fp) 2875 { 2876 /* And this may overflow. */ 2877 double test = png_pow10(exp_b10+1); 2878 2879 if (test <= DBL_MAX) 2880 ++exp_b10, base = test; 2881 2882 else 2883 break; 2884 } 2885 2886 /* Normalize fp and correct exp_b10, after this fp is in the 2887 * range [.1,1) and exp_b10 is both the exponent and the digit 2888 * *before* which the decimal point should be inserted 2889 * (starting with 0 for the first digit). Note that this 2890 * works even if 10^exp_b10 is out of range because of the 2891 * test on DBL_MAX above. 2892 */ 2893 fp /= base; 2894 while (fp >= 1) fp /= 10, ++exp_b10; 2895 2896 /* Because of the code above fp may, at this point, be 2897 * less than .1, this is ok because the code below can 2898 * handle the leading zeros this generates, so no attempt 2899 * is made to correct that here. 2900 */ 2901 2902 { 2903 unsigned int czero, clead, cdigits; 2904 char exponent[10]; 2905 2906 /* Allow up to two leading zeros - this will not lengthen 2907 * the number compared to using E-n. 2908 */ 2909 if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */ 2910 { 2911 czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */ 2912 exp_b10 = 0; /* Dot added below before first output. */ 2913 } 2914 else 2915 czero = 0; /* No zeros to add */ 2916 2917 /* Generate the digit list, stripping trailing zeros and 2918 * inserting a '.' before a digit if the exponent is 0. 2919 */ 2920 clead = czero; /* Count of leading zeros */ 2921 cdigits = 0; /* Count of digits in list. */ 2922 2923 do 2924 { 2925 double d; 2926 2927 fp *= 10; 2928 /* Use modf here, not floor and subtract, so that 2929 * the separation is done in one step. At the end 2930 * of the loop don't break the number into parts so 2931 * that the final digit is rounded. 2932 */ 2933 if (cdigits+czero+1 < precision+clead) 2934 fp = modf(fp, &d); 2935 2936 else 2937 { 2938 d = floor(fp + .5); 2939 2940 if (d > 9) 2941 { 2942 /* Rounding up to 10, handle that here. */ 2943 if (czero > 0) 2944 { 2945 --czero, d = 1; 2946 if (cdigits == 0) --clead; 2947 } 2948 else 2949 { 2950 while (cdigits > 0 && d > 9) 2951 { 2952 int ch = *--ascii; 2953 2954 if (exp_b10 != (-1)) 2955 ++exp_b10; 2956 2957 else if (ch == 46) 2958 { 2959 ch = *--ascii, ++size; 2960 /* Advance exp_b10 to '1', so that the 2961 * decimal point happens after the 2962 * previous digit. 2963 */ 2964 exp_b10 = 1; 2965 } 2966 2967 --cdigits; 2968 d = ch - 47; /* I.e. 1+(ch-48) */ 2969 } 2970 2971 /* Did we reach the beginning? If so adjust the 2972 * exponent but take into account the leading 2973 * decimal point. 2974 */ 2975 if (d > 9) /* cdigits == 0 */ 2976 { 2977 if (exp_b10 == (-1)) 2978 { 2979 /* Leading decimal point (plus zeros?), if 2980 * we lose the decimal point here it must 2981 * be reentered below. 2982 */ 2983 int ch = *--ascii; 2984 2985 if (ch == 46) 2986 ++size, exp_b10 = 1; 2987 2988 /* Else lost a leading zero, so 'exp_b10' is 2989 * still ok at (-1) 2990 */ 2991 } 2992 else 2993 ++exp_b10; 2994 2995 /* In all cases we output a '1' */ 2996 d = 1; 2997 } 2998 } 2999 } 3000 fp = 0; /* Guarantees termination below. */ 3001 } 3002 3003 if (d == 0) 3004 { 3005 ++czero; 3006 if (cdigits == 0) ++clead; 3007 } 3008 else 3009 { 3010 /* Included embedded zeros in the digit count. */ 3011 cdigits += czero - clead; 3012 clead = 0; 3013 3014 while (czero > 0) 3015 { 3016 /* exp_b10 == (-1) means we just output the decimal 3017 * place - after the DP don't adjust 'exp_b10' any 3018 * more! 3019 */ 3020 if (exp_b10 != (-1)) 3021 { 3022 if (exp_b10 == 0) *ascii++ = 46, --size; 3023 /* PLUS 1: TOTAL 4 */ 3024 --exp_b10; 3025 } 3026 *ascii++ = 48, --czero; 3027 } 3028 3029 if (exp_b10 != (-1)) 3030 { 3031 if (exp_b10 == 0) 3032 *ascii++ = 46, --size; /* counted above */ 3033 3034 --exp_b10; 3035 } 3036 *ascii++ = (char)(48 + (int)d), ++cdigits; 3037 } 3038 } 3039 while (cdigits+czero < precision+clead && fp > DBL_MIN); 3040 3041 /* The total output count (max) is now 4+precision */ 3042 3043 /* Check for an exponent, if we don't need one we are 3044 * done and just need to terminate the string. At 3045 * this point exp_b10==(-1) is effectively if flag - it got 3046 * to '-1' because of the decrement after outputting 3047 * the decimal point above (the exponent required is 3048 * *not* -1!) 3049 */ 3050 if (exp_b10 >= (-1) && exp_b10 <= 2) 3051 { 3052 /* The following only happens if we didn't output the 3053 * leading zeros above for negative exponent, so this 3054 * doesn't add to the digit requirement. Note that the 3055 * two zeros here can only be output if the two leading 3056 * zeros were *not* output, so this doesn't increase 3057 * the output count. 3058 */ 3059 while (--exp_b10 >= 0) *ascii++ = 48; 3060 3061 *ascii = 0; 3062 3063 /* Total buffer requirement (including the '\0') is 3064 * 5+precision - see check at the start. 3065 */ 3066 return; 3067 } 3068 3069 /* Here if an exponent is required, adjust size for 3070 * the digits we output but did not count. The total 3071 * digit output here so far is at most 1+precision - no 3072 * decimal point and no leading or trailing zeros have 3073 * been output. 3074 */ 3075 size -= cdigits; 3076 3077 *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */ 3078 3079 /* The following use of an unsigned temporary avoids ambiguities in 3080 * the signed arithmetic on exp_b10 and permits GCC at least to do 3081 * better optimization. 3082 */ 3083 { 3084 unsigned int uexp_b10; 3085 3086 if (exp_b10 < 0) 3087 { 3088 *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */ 3089 uexp_b10 = -exp_b10; 3090 } 3091 3092 else 3093 uexp_b10 = exp_b10; 3094 3095 cdigits = 0; 3096 3097 while (uexp_b10 > 0) 3098 { 3099 exponent[cdigits++] = (char)(48 + uexp_b10 % 10); 3100 uexp_b10 /= 10; 3101 } 3102 } 3103 3104 /* Need another size check here for the exponent digits, so 3105 * this need not be considered above. 3106 */ 3107 if (size > cdigits) 3108 { 3109 while (cdigits > 0) *ascii++ = exponent[--cdigits]; 3110 3111 *ascii = 0; 3112 3113 return; 3114 } 3115 } 3116 } 3117 else if (!(fp >= DBL_MIN)) 3118 { 3119 *ascii++ = 48; /* '0' */ 3120 *ascii = 0; 3121 return; 3122 } 3123 else 3124 { 3125 *ascii++ = 105; /* 'i' */ 3126 *ascii++ = 110; /* 'n' */ 3127 *ascii++ = 102; /* 'f' */ 3128 *ascii = 0; 3129 return; 3130 } 3131 } 3132 3133 /* Here on buffer too small. */ 3134 png_error(png_ptr, "ASCII conversion buffer too small"); 3135} 3136 3137# endif /* FLOATING_POINT */ 3138 3139# ifdef PNG_FIXED_POINT_SUPPORTED 3140/* Function to format a fixed point value in ASCII. 3141 */ 3142void /* PRIVATE */ 3143png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii, 3144 png_size_t size, png_fixed_point fp) 3145{ 3146 /* Require space for 10 decimal digits, a decimal point, a minus sign and a 3147 * trailing \0, 13 characters: 3148 */ 3149 if (size > 12) 3150 { 3151 png_uint_32 num; 3152 3153 /* Avoid overflow here on the minimum integer. */ 3154 if (fp < 0) 3155 *ascii++ = 45, num = -fp; 3156 else 3157 num = fp; 3158 3159 if (num <= 0x80000000) /* else overflowed */ 3160 { 3161 unsigned int ndigits = 0, first = 16 /* flag value */; 3162 char digits[10]; 3163 3164 while (num) 3165 { 3166 /* Split the low digit off num: */ 3167 unsigned int tmp = num/10; 3168 num -= tmp*10; 3169 digits[ndigits++] = (char)(48 + num); 3170 /* Record the first non-zero digit, note that this is a number 3171 * starting at 1, it's not actually the array index. 3172 */ 3173 if (first == 16 && num > 0) 3174 first = ndigits; 3175 num = tmp; 3176 } 3177 3178 if (ndigits > 0) 3179 { 3180 while (ndigits > 5) *ascii++ = digits[--ndigits]; 3181 /* The remaining digits are fractional digits, ndigits is '5' or 3182 * smaller at this point. It is certainly not zero. Check for a 3183 * non-zero fractional digit: 3184 */ 3185 if (first <= 5) 3186 { 3187 unsigned int i; 3188 *ascii++ = 46; /* decimal point */ 3189 /* ndigits may be <5 for small numbers, output leading zeros 3190 * then ndigits digits to first: 3191 */ 3192 i = 5; 3193 while (ndigits < i) *ascii++ = 48, --i; 3194 while (ndigits >= first) *ascii++ = digits[--ndigits]; 3195 /* Don't output the trailing zeros! */ 3196 } 3197 } 3198 else 3199 *ascii++ = 48; 3200 3201 /* And null terminate the string: */ 3202 *ascii = 0; 3203 return; 3204 } 3205 } 3206 3207 /* Here on buffer too small. */ 3208 png_error(png_ptr, "ASCII conversion buffer too small"); 3209} 3210# endif /* FIXED_POINT */ 3211#endif /* SCAL */ 3212 3213#if defined(PNG_FLOATING_POINT_SUPPORTED) && \ 3214 !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \ 3215 (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \ 3216 defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \ 3217 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \ 3218 (defined(PNG_sCAL_SUPPORTED) && \ 3219 defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)) 3220png_fixed_point 3221png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text) 3222{ 3223 double r = floor(100000 * fp + .5); 3224 3225 if (r > 2147483647. || r < -2147483648.) 3226 png_fixed_error(png_ptr, text); 3227 3228# ifndef PNG_ERROR_TEXT_SUPPORTED 3229 PNG_UNUSED(text) 3230# endif 3231 3232 return (png_fixed_point)r; 3233} 3234#endif 3235 3236#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\ 3237 defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED) 3238/* muldiv functions */ 3239/* This API takes signed arguments and rounds the result to the nearest 3240 * integer (or, for a fixed point number - the standard argument - to 3241 * the nearest .00001). Overflow and divide by zero are signalled in 3242 * the result, a boolean - true on success, false on overflow. 3243 */ 3244int 3245png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times, 3246 png_int_32 divisor) 3247{ 3248 /* Return a * times / divisor, rounded. */ 3249 if (divisor != 0) 3250 { 3251 if (a == 0 || times == 0) 3252 { 3253 *res = 0; 3254 return 1; 3255 } 3256 else 3257 { 3258#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED 3259 double r = a; 3260 r *= times; 3261 r /= divisor; 3262 r = floor(r+.5); 3263 3264 /* A png_fixed_point is a 32-bit integer. */ 3265 if (r <= 2147483647. && r >= -2147483648.) 3266 { 3267 *res = (png_fixed_point)r; 3268 return 1; 3269 } 3270#else 3271 int negative = 0; 3272 png_uint_32 A, T, D; 3273 png_uint_32 s16, s32, s00; 3274 3275 if (a < 0) 3276 negative = 1, A = -a; 3277 else 3278 A = a; 3279 3280 if (times < 0) 3281 negative = !negative, T = -times; 3282 else 3283 T = times; 3284 3285 if (divisor < 0) 3286 negative = !negative, D = -divisor; 3287 else 3288 D = divisor; 3289 3290 /* Following can't overflow because the arguments only 3291 * have 31 bits each, however the result may be 32 bits. 3292 */ 3293 s16 = (A >> 16) * (T & 0xffff) + 3294 (A & 0xffff) * (T >> 16); 3295 /* Can't overflow because the a*times bit is only 30 3296 * bits at most. 3297 */ 3298 s32 = (A >> 16) * (T >> 16) + (s16 >> 16); 3299 s00 = (A & 0xffff) * (T & 0xffff); 3300 3301 s16 = (s16 & 0xffff) << 16; 3302 s00 += s16; 3303 3304 if (s00 < s16) 3305 ++s32; /* carry */ 3306 3307 if (s32 < D) /* else overflow */ 3308 { 3309 /* s32.s00 is now the 64-bit product, do a standard 3310 * division, we know that s32 < D, so the maximum 3311 * required shift is 31. 3312 */ 3313 int bitshift = 32; 3314 png_fixed_point result = 0; /* NOTE: signed */ 3315 3316 while (--bitshift >= 0) 3317 { 3318 png_uint_32 d32, d00; 3319 3320 if (bitshift > 0) 3321 d32 = D >> (32-bitshift), d00 = D << bitshift; 3322 3323 else 3324 d32 = 0, d00 = D; 3325 3326 if (s32 > d32) 3327 { 3328 if (s00 < d00) --s32; /* carry */ 3329 s32 -= d32, s00 -= d00, result += 1<<bitshift; 3330 } 3331 3332 else 3333 if (s32 == d32 && s00 >= d00) 3334 s32 = 0, s00 -= d00, result += 1<<bitshift; 3335 } 3336 3337 /* Handle the rounding. */ 3338 if (s00 >= (D >> 1)) 3339 ++result; 3340 3341 if (negative != 0) 3342 result = -result; 3343 3344 /* Check for overflow. */ 3345 if ((negative != 0 && result <= 0) || 3346 (negative == 0 && result >= 0)) 3347 { 3348 *res = result; 3349 return 1; 3350 } 3351 } 3352#endif 3353 } 3354 } 3355 3356 return 0; 3357} 3358#endif /* READ_GAMMA || INCH_CONVERSIONS */ 3359 3360#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED) 3361/* The following is for when the caller doesn't much care about the 3362 * result. 3363 */ 3364png_fixed_point 3365png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times, 3366 png_int_32 divisor) 3367{ 3368 png_fixed_point result; 3369 3370 if (png_muldiv(&result, a, times, divisor) != 0) 3371 return result; 3372 3373 png_warning(png_ptr, "fixed point overflow ignored"); 3374 return 0; 3375} 3376#endif 3377 3378#ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */ 3379/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */ 3380png_fixed_point 3381png_reciprocal(png_fixed_point a) 3382{ 3383#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED 3384 double r = floor(1E10/a+.5); 3385 3386 if (r <= 2147483647. && r >= -2147483648.) 3387 return (png_fixed_point)r; 3388#else 3389 png_fixed_point res; 3390 3391 if (png_muldiv(&res, 100000, 100000, a) != 0) 3392 return res; 3393#endif 3394 3395 return 0; /* error/overflow */ 3396} 3397 3398/* This is the shared test on whether a gamma value is 'significant' - whether 3399 * it is worth doing gamma correction. 3400 */ 3401int /* PRIVATE */ 3402png_gamma_significant(png_fixed_point gamma_val) 3403{ 3404 return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED || 3405 gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED; 3406} 3407#endif 3408 3409#ifdef PNG_READ_GAMMA_SUPPORTED 3410#ifdef PNG_16BIT_SUPPORTED 3411/* A local convenience routine. */ 3412static png_fixed_point 3413png_product2(png_fixed_point a, png_fixed_point b) 3414{ 3415 /* The required result is 1/a * 1/b; the following preserves accuracy. */ 3416#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED 3417 double r = a * 1E-5; 3418 r *= b; 3419 r = floor(r+.5); 3420 3421 if (r <= 2147483647. && r >= -2147483648.) 3422 return (png_fixed_point)r; 3423#else 3424 png_fixed_point res; 3425 3426 if (png_muldiv(&res, a, b, 100000) != 0) 3427 return res; 3428#endif 3429 3430 return 0; /* overflow */ 3431} 3432#endif /* 16BIT */ 3433 3434/* The inverse of the above. */ 3435png_fixed_point 3436png_reciprocal2(png_fixed_point a, png_fixed_point b) 3437{ 3438 /* The required result is 1/a * 1/b; the following preserves accuracy. */ 3439#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED 3440 if (a != 0 && b != 0) 3441 { 3442 double r = 1E15/a; 3443 r /= b; 3444 r = floor(r+.5); 3445 3446 if (r <= 2147483647. && r >= -2147483648.) 3447 return (png_fixed_point)r; 3448 } 3449#else 3450 /* This may overflow because the range of png_fixed_point isn't symmetric, 3451 * but this API is only used for the product of file and screen gamma so it 3452 * doesn't matter that the smallest number it can produce is 1/21474, not 3453 * 1/100000 3454 */ 3455 png_fixed_point res = png_product2(a, b); 3456 3457 if (res != 0) 3458 return png_reciprocal(res); 3459#endif 3460 3461 return 0; /* overflow */ 3462} 3463#endif /* READ_GAMMA */ 3464 3465#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */ 3466#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED 3467/* Fixed point gamma. 3468 * 3469 * The code to calculate the tables used below can be found in the shell script 3470 * contrib/tools/intgamma.sh 3471 * 3472 * To calculate gamma this code implements fast log() and exp() calls using only 3473 * fixed point arithmetic. This code has sufficient precision for either 8-bit 3474 * or 16-bit sample values. 3475 * 3476 * The tables used here were calculated using simple 'bc' programs, but C double 3477 * precision floating point arithmetic would work fine. 3478 * 3479 * 8-bit log table 3480 * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to 3481 * 255, so it's the base 2 logarithm of a normalized 8-bit floating point 3482 * mantissa. The numbers are 32-bit fractions. 3483 */ 3484static const png_uint_32 3485png_8bit_l2[128] = 3486{ 3487 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U, 3488 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U, 3489 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U, 3490 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U, 3491 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U, 3492 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U, 3493 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U, 3494 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U, 3495 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U, 3496 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U, 3497 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U, 3498 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U, 3499 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U, 3500 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U, 3501 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U, 3502 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U, 3503 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U, 3504 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U, 3505 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U, 3506 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U, 3507 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U, 3508 24347096U, 0U 3509 3510#if 0 3511 /* The following are the values for 16-bit tables - these work fine for the 3512 * 8-bit conversions but produce very slightly larger errors in the 16-bit 3513 * log (about 1.2 as opposed to 0.7 absolute error in the final value). To 3514 * use these all the shifts below must be adjusted appropriately. 3515 */ 3516 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054, 3517 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803, 3518 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068, 3519 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782, 3520 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887, 3521 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339, 3522 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098, 3523 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132, 3524 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415, 3525 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523, 3526 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495, 3527 1119, 744, 372 3528#endif 3529}; 3530 3531static png_int_32 3532png_log8bit(unsigned int x) 3533{ 3534 unsigned int lg2 = 0; 3535 /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log, 3536 * because the log is actually negate that means adding 1. The final 3537 * returned value thus has the range 0 (for 255 input) to 7.994 (for 1 3538 * input), return -1 for the overflow (log 0) case, - so the result is 3539 * always at most 19 bits. 3540 */ 3541 if ((x &= 0xff) == 0) 3542 return -1; 3543 3544 if ((x & 0xf0) == 0) 3545 lg2 = 4, x <<= 4; 3546 3547 if ((x & 0xc0) == 0) 3548 lg2 += 2, x <<= 2; 3549 3550 if ((x & 0x80) == 0) 3551 lg2 += 1, x <<= 1; 3552 3553 /* result is at most 19 bits, so this cast is safe: */ 3554 return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16)); 3555} 3556 3557/* The above gives exact (to 16 binary places) log2 values for 8-bit images, 3558 * for 16-bit images we use the most significant 8 bits of the 16-bit value to 3559 * get an approximation then multiply the approximation by a correction factor 3560 * determined by the remaining up to 8 bits. This requires an additional step 3561 * in the 16-bit case. 3562 * 3563 * We want log2(value/65535), we have log2(v'/255), where: 3564 * 3565 * value = v' * 256 + v'' 3566 * = v' * f 3567 * 3568 * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128 3569 * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less 3570 * than 258. The final factor also needs to correct for the fact that our 8-bit 3571 * value is scaled by 255, whereas the 16-bit values must be scaled by 65535. 3572 * 3573 * This gives a final formula using a calculated value 'x' which is value/v' and 3574 * scaling by 65536 to match the above table: 3575 * 3576 * log2(x/257) * 65536 3577 * 3578 * Since these numbers are so close to '1' we can use simple linear 3579 * interpolation between the two end values 256/257 (result -368.61) and 258/257 3580 * (result 367.179). The values used below are scaled by a further 64 to give 3581 * 16-bit precision in the interpolation: 3582 * 3583 * Start (256): -23591 3584 * Zero (257): 0 3585 * End (258): 23499 3586 */ 3587#ifdef PNG_16BIT_SUPPORTED 3588static png_int_32 3589png_log16bit(png_uint_32 x) 3590{ 3591 unsigned int lg2 = 0; 3592 3593 /* As above, but now the input has 16 bits. */ 3594 if ((x &= 0xffff) == 0) 3595 return -1; 3596 3597 if ((x & 0xff00) == 0) 3598 lg2 = 8, x <<= 8; 3599 3600 if ((x & 0xf000) == 0) 3601 lg2 += 4, x <<= 4; 3602 3603 if ((x & 0xc000) == 0) 3604 lg2 += 2, x <<= 2; 3605 3606 if ((x & 0x8000) == 0) 3607 lg2 += 1, x <<= 1; 3608 3609 /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional 3610 * value. 3611 */ 3612 lg2 <<= 28; 3613 lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4; 3614 3615 /* Now we need to interpolate the factor, this requires a division by the top 3616 * 8 bits. Do this with maximum precision. 3617 */ 3618 x = ((x << 16) + (x >> 9)) / (x >> 8); 3619 3620 /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24, 3621 * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly 3622 * 16 bits to interpolate to get the low bits of the result. Round the 3623 * answer. Note that the end point values are scaled by 64 to retain overall 3624 * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust 3625 * the overall scaling by 6-12. Round at every step. 3626 */ 3627 x -= 1U << 24; 3628 3629 if (x <= 65536U) /* <= '257' */ 3630 lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12); 3631 3632 else 3633 lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12); 3634 3635 /* Safe, because the result can't have more than 20 bits: */ 3636 return (png_int_32)((lg2 + 2048) >> 12); 3637} 3638#endif /* 16BIT */ 3639 3640/* The 'exp()' case must invert the above, taking a 20-bit fixed point 3641 * logarithmic value and returning a 16 or 8-bit number as appropriate. In 3642 * each case only the low 16 bits are relevant - the fraction - since the 3643 * integer bits (the top 4) simply determine a shift. 3644 * 3645 * The worst case is the 16-bit distinction between 65535 and 65534. This 3646 * requires perhaps spurious accuracy in the decoding of the logarithm to 3647 * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance 3648 * of getting this accuracy in practice. 3649 * 3650 * To deal with this the following exp() function works out the exponent of the 3651 * frational part of the logarithm by using an accurate 32-bit value from the 3652 * top four fractional bits then multiplying in the remaining bits. 3653 */ 3654static const png_uint_32 3655png_32bit_exp[16] = 3656{ 3657 /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */ 3658 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U, 3659 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U, 3660 2553802834U, 2445529972U, 2341847524U, 2242560872U 3661}; 3662 3663/* Adjustment table; provided to explain the numbers in the code below. */ 3664#if 0 3665for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"} 3666 11 44937.64284865548751208448 3667 10 45180.98734845585101160448 3668 9 45303.31936980687359311872 3669 8 45364.65110595323018870784 3670 7 45395.35850361789624614912 3671 6 45410.72259715102037508096 3672 5 45418.40724413220722311168 3673 4 45422.25021786898173001728 3674 3 45424.17186732298419044352 3675 2 45425.13273269940811464704 3676 1 45425.61317555035558641664 3677 0 45425.85339951654943850496 3678#endif 3679 3680static png_uint_32 3681png_exp(png_fixed_point x) 3682{ 3683 if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */ 3684 { 3685 /* Obtain a 4-bit approximation */ 3686 png_uint_32 e = png_32bit_exp[(x >> 12) & 0x0f]; 3687 3688 /* Incorporate the low 12 bits - these decrease the returned value by 3689 * multiplying by a number less than 1 if the bit is set. The multiplier 3690 * is determined by the above table and the shift. Notice that the values 3691 * converge on 45426 and this is used to allow linear interpolation of the 3692 * low bits. 3693 */ 3694 if (x & 0x800) 3695 e -= (((e >> 16) * 44938U) + 16U) >> 5; 3696 3697 if (x & 0x400) 3698 e -= (((e >> 16) * 45181U) + 32U) >> 6; 3699 3700 if (x & 0x200) 3701 e -= (((e >> 16) * 45303U) + 64U) >> 7; 3702 3703 if (x & 0x100) 3704 e -= (((e >> 16) * 45365U) + 128U) >> 8; 3705 3706 if (x & 0x080) 3707 e -= (((e >> 16) * 45395U) + 256U) >> 9; 3708 3709 if (x & 0x040) 3710 e -= (((e >> 16) * 45410U) + 512U) >> 10; 3711 3712 /* And handle the low 6 bits in a single block. */ 3713 e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9; 3714 3715 /* Handle the upper bits of x. */ 3716 e >>= x >> 16; 3717 return e; 3718 } 3719 3720 /* Check for overflow */ 3721 if (x <= 0) 3722 return png_32bit_exp[0]; 3723 3724 /* Else underflow */ 3725 return 0; 3726} 3727 3728static png_byte 3729png_exp8bit(png_fixed_point lg2) 3730{ 3731 /* Get a 32-bit value: */ 3732 png_uint_32 x = png_exp(lg2); 3733 3734 /* Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the 3735 * second, rounding, step can't overflow because of the first, subtraction, 3736 * step. 3737 */ 3738 x -= x >> 8; 3739 return (png_byte)(((x + 0x7fffffU) >> 24) & 0xff); 3740} 3741 3742#ifdef PNG_16BIT_SUPPORTED 3743static png_uint_16 3744png_exp16bit(png_fixed_point lg2) 3745{ 3746 /* Get a 32-bit value: */ 3747 png_uint_32 x = png_exp(lg2); 3748 3749 /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */ 3750 x -= x >> 16; 3751 return (png_uint_16)((x + 32767U) >> 16); 3752} 3753#endif /* 16BIT */ 3754#endif /* FLOATING_ARITHMETIC */ 3755 3756png_byte 3757png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val) 3758{ 3759 if (value > 0 && value < 255) 3760 { 3761# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED 3762 /* 'value' is unsigned, ANSI-C90 requires the compiler to correctly 3763 * convert this to a floating point value. This includes values that 3764 * would overflow if 'value' were to be converted to 'int'. 3765 * 3766 * Apparently GCC, however, does an intermediate conversion to (int) 3767 * on some (ARM) but not all (x86) platforms, possibly because of 3768 * hardware FP limitations. (E.g. if the hardware conversion always 3769 * assumes the integer register contains a signed value.) This results 3770 * in ANSI-C undefined behavior for large values. 3771 * 3772 * Other implementations on the same machine might actually be ANSI-C90 3773 * conformant and therefore compile spurious extra code for the large 3774 * values. 3775 * 3776 * We can be reasonably sure that an unsigned to float conversion 3777 * won't be faster than an int to float one. Therefore this code 3778 * assumes responsibility for the undefined behavior, which it knows 3779 * can't happen because of the check above. 3780 * 3781 * Note the argument to this routine is an (unsigned int) because, on 3782 * 16-bit platforms, it is assigned a value which might be out of 3783 * range for an (int); that would result in undefined behavior in the 3784 * caller if the *argument* ('value') were to be declared (int). 3785 */ 3786 double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5); 3787 return (png_byte)r; 3788# else 3789 png_int_32 lg2 = png_log8bit(value); 3790 png_fixed_point res; 3791 3792 if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0) 3793 return png_exp8bit(res); 3794 3795 /* Overflow. */ 3796 value = 0; 3797# endif 3798 } 3799 3800 return (png_byte)(value & 0xff); 3801} 3802 3803#ifdef PNG_16BIT_SUPPORTED 3804png_uint_16 3805png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val) 3806{ 3807 if (value > 0 && value < 65535) 3808 { 3809# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED 3810 /* The same (unsigned int)->(double) constraints apply here as above, 3811 * however in this case the (unsigned int) to (int) conversion can 3812 * overflow on an ANSI-C90 compliant system so the cast needs to ensure 3813 * that this is not possible. 3814 */ 3815 double r = floor(65535*pow((png_int_32)value/65535., 3816 gamma_val*.00001)+.5); 3817 return (png_uint_16)r; 3818# else 3819 png_int_32 lg2 = png_log16bit(value); 3820 png_fixed_point res; 3821 3822 if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0) 3823 return png_exp16bit(res); 3824 3825 /* Overflow. */ 3826 value = 0; 3827# endif 3828 } 3829 3830 return (png_uint_16)value; 3831} 3832#endif /* 16BIT */ 3833 3834/* This does the right thing based on the bit_depth field of the 3835 * png_struct, interpreting values as 8-bit or 16-bit. While the result 3836 * is nominally a 16-bit value if bit depth is 8 then the result is 3837 * 8-bit (as are the arguments.) 3838 */ 3839png_uint_16 /* PRIVATE */ 3840png_gamma_correct(png_structrp png_ptr, unsigned int value, 3841 png_fixed_point gamma_val) 3842{ 3843 if (png_ptr->bit_depth == 8) 3844 return png_gamma_8bit_correct(value, gamma_val); 3845 3846#ifdef PNG_16BIT_SUPPORTED 3847 else 3848 return png_gamma_16bit_correct(value, gamma_val); 3849#else 3850 /* should not reach this */ 3851 return 0; 3852#endif /* 16BIT */ 3853} 3854 3855#ifdef PNG_16BIT_SUPPORTED 3856/* Internal function to build a single 16-bit table - the table consists of 3857 * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount 3858 * to shift the input values right (or 16-number_of_signifiant_bits). 3859 * 3860 * The caller is responsible for ensuring that the table gets cleaned up on 3861 * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument 3862 * should be somewhere that will be cleaned. 3863 */ 3864static void 3865png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable, 3866 PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) 3867{ 3868 /* Various values derived from 'shift': */ 3869 PNG_CONST unsigned int num = 1U << (8U - shift); 3870#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED 3871 /* CSE the division and work round wacky GCC warnings (see the comments 3872 * in png_gamma_8bit_correct for where these come from.) 3873 */ 3874 PNG_CONST double fmax = 1./(((png_int_32)1 << (16U - shift))-1); 3875#endif 3876 PNG_CONST unsigned int max = (1U << (16U - shift))-1U; 3877 PNG_CONST unsigned int max_by_2 = 1U << (15U-shift); 3878 unsigned int i; 3879 3880 png_uint_16pp table = *ptable = 3881 (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p))); 3882 3883 for (i = 0; i < num; i++) 3884 { 3885 png_uint_16p sub_table = table[i] = 3886 (png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16))); 3887 3888 /* The 'threshold' test is repeated here because it can arise for one of 3889 * the 16-bit tables even if the others don't hit it. 3890 */ 3891 if (png_gamma_significant(gamma_val) != 0) 3892 { 3893 /* The old code would overflow at the end and this would cause the 3894 * 'pow' function to return a result >1, resulting in an 3895 * arithmetic error. This code follows the spec exactly; ig is 3896 * the recovered input sample, it always has 8-16 bits. 3897 * 3898 * We want input * 65535/max, rounded, the arithmetic fits in 32 3899 * bits (unsigned) so long as max <= 32767. 3900 */ 3901 unsigned int j; 3902 for (j = 0; j < 256; j++) 3903 { 3904 png_uint_32 ig = (j << (8-shift)) + i; 3905# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED 3906 /* Inline the 'max' scaling operation: */ 3907 /* See png_gamma_8bit_correct for why the cast to (int) is 3908 * required here. 3909 */ 3910 double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5); 3911 sub_table[j] = (png_uint_16)d; 3912# else 3913 if (shift != 0) 3914 ig = (ig * 65535U + max_by_2)/max; 3915 3916 sub_table[j] = png_gamma_16bit_correct(ig, gamma_val); 3917# endif 3918 } 3919 } 3920 else 3921 { 3922 /* We must still build a table, but do it the fast way. */ 3923 unsigned int j; 3924 3925 for (j = 0; j < 256; j++) 3926 { 3927 png_uint_32 ig = (j << (8-shift)) + i; 3928 3929 if (shift != 0) 3930 ig = (ig * 65535U + max_by_2)/max; 3931 3932 sub_table[j] = (png_uint_16)ig; 3933 } 3934 } 3935 } 3936} 3937 3938/* NOTE: this function expects the *inverse* of the overall gamma transformation 3939 * required. 3940 */ 3941static void 3942png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable, 3943 PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) 3944{ 3945 PNG_CONST unsigned int num = 1U << (8U - shift); 3946 PNG_CONST unsigned int max = (1U << (16U - shift))-1U; 3947 unsigned int i; 3948 png_uint_32 last; 3949 3950 png_uint_16pp table = *ptable = 3951 (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p))); 3952 3953 /* 'num' is the number of tables and also the number of low bits of low 3954 * bits of the input 16-bit value used to select a table. Each table is 3955 * itself indexed by the high 8 bits of the value. 3956 */ 3957 for (i = 0; i < num; i++) 3958 table[i] = (png_uint_16p)png_malloc(png_ptr, 3959 256 * (sizeof (png_uint_16))); 3960 3961 /* 'gamma_val' is set to the reciprocal of the value calculated above, so 3962 * pow(out,g) is an *input* value. 'last' is the last input value set. 3963 * 3964 * In the loop 'i' is used to find output values. Since the output is 3965 * 8-bit there are only 256 possible values. The tables are set up to 3966 * select the closest possible output value for each input by finding 3967 * the input value at the boundary between each pair of output values 3968 * and filling the table up to that boundary with the lower output 3969 * value. 3970 * 3971 * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit 3972 * values the code below uses a 16-bit value in i; the values start at 3973 * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last 3974 * entries are filled with 255). Start i at 128 and fill all 'last' 3975 * table entries <= 'max' 3976 */ 3977 last = 0; 3978 for (i = 0; i < 255; ++i) /* 8-bit output value */ 3979 { 3980 /* Find the corresponding maximum input value */ 3981 png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */ 3982 3983 /* Find the boundary value in 16 bits: */ 3984 png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val); 3985 3986 /* Adjust (round) to (16-shift) bits: */ 3987 bound = (bound * max + 32768U)/65535U + 1U; 3988 3989 while (last < bound) 3990 { 3991 table[last & (0xffU >> shift)][last >> (8U - shift)] = out; 3992 last++; 3993 } 3994 } 3995 3996 /* And fill in the final entries. */ 3997 while (last < (num << 8)) 3998 { 3999 table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U; 4000 last++; 4001 } 4002} 4003#endif /* 16BIT */ 4004 4005/* Build a single 8-bit table: same as the 16-bit case but much simpler (and 4006 * typically much faster). Note that libpng currently does no sBIT processing 4007 * (apparently contrary to the spec) so a 256-entry table is always generated. 4008 */ 4009static void 4010png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable, 4011 PNG_CONST png_fixed_point gamma_val) 4012{ 4013 unsigned int i; 4014 png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256); 4015 4016 if (png_gamma_significant(gamma_val) != 0) 4017 for (i=0; i<256; i++) 4018 table[i] = png_gamma_8bit_correct(i, gamma_val); 4019 4020 else 4021 for (i=0; i<256; ++i) 4022 table[i] = (png_byte)(i & 0xff); 4023} 4024 4025/* Used from png_read_destroy and below to release the memory used by the gamma 4026 * tables. 4027 */ 4028void /* PRIVATE */ 4029png_destroy_gamma_table(png_structrp png_ptr) 4030{ 4031 png_free(png_ptr, png_ptr->gamma_table); 4032 png_ptr->gamma_table = NULL; 4033 4034#ifdef PNG_16BIT_SUPPORTED 4035 if (png_ptr->gamma_16_table != NULL) 4036 { 4037 int i; 4038 int istop = (1 << (8 - png_ptr->gamma_shift)); 4039 for (i = 0; i < istop; i++) 4040 { 4041 png_free(png_ptr, png_ptr->gamma_16_table[i]); 4042 } 4043 png_free(png_ptr, png_ptr->gamma_16_table); 4044 png_ptr->gamma_16_table = NULL; 4045 } 4046#endif /* 16BIT */ 4047 4048#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ 4049 defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ 4050 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) 4051 png_free(png_ptr, png_ptr->gamma_from_1); 4052 png_ptr->gamma_from_1 = NULL; 4053 png_free(png_ptr, png_ptr->gamma_to_1); 4054 png_ptr->gamma_to_1 = NULL; 4055 4056#ifdef PNG_16BIT_SUPPORTED 4057 if (png_ptr->gamma_16_from_1 != NULL) 4058 { 4059 int i; 4060 int istop = (1 << (8 - png_ptr->gamma_shift)); 4061 for (i = 0; i < istop; i++) 4062 { 4063 png_free(png_ptr, png_ptr->gamma_16_from_1[i]); 4064 } 4065 png_free(png_ptr, png_ptr->gamma_16_from_1); 4066 png_ptr->gamma_16_from_1 = NULL; 4067 } 4068 if (png_ptr->gamma_16_to_1 != NULL) 4069 { 4070 int i; 4071 int istop = (1 << (8 - png_ptr->gamma_shift)); 4072 for (i = 0; i < istop; i++) 4073 { 4074 png_free(png_ptr, png_ptr->gamma_16_to_1[i]); 4075 } 4076 png_free(png_ptr, png_ptr->gamma_16_to_1); 4077 png_ptr->gamma_16_to_1 = NULL; 4078 } 4079#endif /* 16BIT */ 4080#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ 4081} 4082 4083/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit 4084 * tables, we don't make a full table if we are reducing to 8-bit in 4085 * the future. Note also how the gamma_16 tables are segmented so that 4086 * we don't need to allocate > 64K chunks for a full 16-bit table. 4087 */ 4088void /* PRIVATE */ 4089png_build_gamma_table(png_structrp png_ptr, int bit_depth) 4090{ 4091 png_debug(1, "in png_build_gamma_table"); 4092 4093 /* Remove any existing table; this copes with multiple calls to 4094 * png_read_update_info. The warning is because building the gamma tables 4095 * multiple times is a performance hit - it's harmless but the ability to call 4096 * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible 4097 * to warn if the app introduces such a hit. 4098 */ 4099 if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL) 4100 { 4101 png_warning(png_ptr, "gamma table being rebuilt"); 4102 png_destroy_gamma_table(png_ptr); 4103 } 4104 4105 if (bit_depth <= 8) 4106 { 4107 png_build_8bit_table(png_ptr, &png_ptr->gamma_table, 4108 png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma, 4109 png_ptr->screen_gamma) : PNG_FP_1); 4110 4111#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ 4112 defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ 4113 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) 4114 if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0) 4115 { 4116 png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1, 4117 png_reciprocal(png_ptr->colorspace.gamma)); 4118 4119 png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1, 4120 png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : 4121 png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */); 4122 } 4123#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ 4124 } 4125#ifdef PNG_16BIT_SUPPORTED 4126 else 4127 { 4128 png_byte shift, sig_bit; 4129 4130 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) 4131 { 4132 sig_bit = png_ptr->sig_bit.red; 4133 4134 if (png_ptr->sig_bit.green > sig_bit) 4135 sig_bit = png_ptr->sig_bit.green; 4136 4137 if (png_ptr->sig_bit.blue > sig_bit) 4138 sig_bit = png_ptr->sig_bit.blue; 4139 } 4140 else 4141 sig_bit = png_ptr->sig_bit.gray; 4142 4143 /* 16-bit gamma code uses this equation: 4144 * 4145 * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8] 4146 * 4147 * Where 'iv' is the input color value and 'ov' is the output value - 4148 * pow(iv, gamma). 4149 * 4150 * Thus the gamma table consists of up to 256 256-entry tables. The table 4151 * is selected by the (8-gamma_shift) most significant of the low 8 bits of 4152 * the color value then indexed by the upper 8 bits: 4153 * 4154 * table[low bits][high 8 bits] 4155 * 4156 * So the table 'n' corresponds to all those 'iv' of: 4157 * 4158 * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1> 4159 * 4160 */ 4161 if (sig_bit > 0 && sig_bit < 16U) 4162 /* shift == insignificant bits */ 4163 shift = (png_byte)((16U - sig_bit) & 0xff); 4164 4165 else 4166 shift = 0; /* keep all 16 bits */ 4167 4168 if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0) 4169 { 4170 /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively 4171 * the significant bits in the *input* when the output will 4172 * eventually be 8 bits. By default it is 11. 4173 */ 4174 if (shift < (16U - PNG_MAX_GAMMA_8)) 4175 shift = (16U - PNG_MAX_GAMMA_8); 4176 } 4177 4178 if (shift > 8U) 4179 shift = 8U; /* Guarantees at least one table! */ 4180 4181 png_ptr->gamma_shift = shift; 4182 4183 /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now 4184 * PNG_COMPOSE). This effectively smashed the background calculation for 4185 * 16-bit output because the 8-bit table assumes the result will be reduced 4186 * to 8 bits. 4187 */ 4188 if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0) 4189 png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift, 4190 png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma, 4191 png_ptr->screen_gamma) : PNG_FP_1); 4192 4193 else 4194 png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift, 4195 png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma, 4196 png_ptr->screen_gamma) : PNG_FP_1); 4197 4198#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ 4199 defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ 4200 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) 4201 if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0) 4202 { 4203 png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift, 4204 png_reciprocal(png_ptr->colorspace.gamma)); 4205 4206 /* Notice that the '16 from 1' table should be full precision, however 4207 * the lookup on this table still uses gamma_shift, so it can't be. 4208 * TODO: fix this. 4209 */ 4210 png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift, 4211 png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : 4212 png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */); 4213 } 4214#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ 4215 } 4216#endif /* 16BIT */ 4217} 4218#endif /* READ_GAMMA */ 4219 4220/* HARDWARE OR SOFTWARE OPTION SUPPORT */ 4221#ifdef PNG_SET_OPTION_SUPPORTED 4222int PNGAPI 4223png_set_option(png_structrp png_ptr, int option, int onoff) 4224{ 4225 if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT && 4226 (option & 1) == 0) 4227 { 4228 int mask = 3 << option; 4229 int setting = (2 + (onoff != 0)) << option; 4230 int current = png_ptr->options; 4231 4232 png_ptr->options = (png_byte)(((current & ~mask) | setting) & 0xff); 4233 4234 return (current & mask) >> option; 4235 } 4236 4237 return PNG_OPTION_INVALID; 4238} 4239#endif 4240 4241/* sRGB support */ 4242#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\ 4243 defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) 4244/* sRGB conversion tables; these are machine generated with the code in 4245 * contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the 4246 * specification (see the article at http://en.wikipedia.org/wiki/SRGB) 4247 * is used, not the gamma=1/2.2 approximation use elsewhere in libpng. 4248 * The sRGB to linear table is exact (to the nearest 16-bit linear fraction). 4249 * The inverse (linear to sRGB) table has accuracies as follows: 4250 * 4251 * For all possible (255*65535+1) input values: 4252 * 4253 * error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact 4254 * 4255 * For the input values corresponding to the 65536 16-bit values: 4256 * 4257 * error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact 4258 * 4259 * In all cases the inexact readings are only off by one. 4260 */ 4261 4262#ifdef PNG_SIMPLIFIED_READ_SUPPORTED 4263/* The convert-to-sRGB table is only currently required for read. */ 4264const png_uint_16 png_sRGB_table[256] = 4265{ 4266 0,20,40,60,80,99,119,139, 4267 159,179,199,219,241,264,288,313, 4268 340,367,396,427,458,491,526,562, 4269 599,637,677,718,761,805,851,898, 4270 947,997,1048,1101,1156,1212,1270,1330, 4271 1391,1453,1517,1583,1651,1720,1790,1863, 4272 1937,2013,2090,2170,2250,2333,2418,2504, 4273 2592,2681,2773,2866,2961,3058,3157,3258, 4274 3360,3464,3570,3678,3788,3900,4014,4129, 4275 4247,4366,4488,4611,4736,4864,4993,5124, 4276 5257,5392,5530,5669,5810,5953,6099,6246, 4277 6395,6547,6700,6856,7014,7174,7335,7500, 4278 7666,7834,8004,8177,8352,8528,8708,8889, 4279 9072,9258,9445,9635,9828,10022,10219,10417, 4280 10619,10822,11028,11235,11446,11658,11873,12090, 4281 12309,12530,12754,12980,13209,13440,13673,13909, 4282 14146,14387,14629,14874,15122,15371,15623,15878, 4283 16135,16394,16656,16920,17187,17456,17727,18001, 4284 18277,18556,18837,19121,19407,19696,19987,20281, 4285 20577,20876,21177,21481,21787,22096,22407,22721, 4286 23038,23357,23678,24002,24329,24658,24990,25325, 4287 25662,26001,26344,26688,27036,27386,27739,28094, 4288 28452,28813,29176,29542,29911,30282,30656,31033, 4289 31412,31794,32179,32567,32957,33350,33745,34143, 4290 34544,34948,35355,35764,36176,36591,37008,37429, 4291 37852,38278,38706,39138,39572,40009,40449,40891, 4292 41337,41785,42236,42690,43147,43606,44069,44534, 4293 45002,45473,45947,46423,46903,47385,47871,48359, 4294 48850,49344,49841,50341,50844,51349,51858,52369, 4295 52884,53401,53921,54445,54971,55500,56032,56567, 4296 57105,57646,58190,58737,59287,59840,60396,60955, 4297 61517,62082,62650,63221,63795,64372,64952,65535 4298}; 4299#endif /* SIMPLIFIED_READ */ 4300 4301/* The base/delta tables are required for both read and write (but currently 4302 * only the simplified versions.) 4303 */ 4304const png_uint_16 png_sRGB_base[512] = 4305{ 4306 128,1782,3383,4644,5675,6564,7357,8074, 4307 8732,9346,9921,10463,10977,11466,11935,12384, 4308 12816,13233,13634,14024,14402,14769,15125,15473, 4309 15812,16142,16466,16781,17090,17393,17690,17981, 4310 18266,18546,18822,19093,19359,19621,19879,20133, 4311 20383,20630,20873,21113,21349,21583,21813,22041, 4312 22265,22487,22707,22923,23138,23350,23559,23767, 4313 23972,24175,24376,24575,24772,24967,25160,25352, 4314 25542,25730,25916,26101,26284,26465,26645,26823, 4315 27000,27176,27350,27523,27695,27865,28034,28201, 4316 28368,28533,28697,28860,29021,29182,29341,29500, 4317 29657,29813,29969,30123,30276,30429,30580,30730, 4318 30880,31028,31176,31323,31469,31614,31758,31902, 4319 32045,32186,32327,32468,32607,32746,32884,33021, 4320 33158,33294,33429,33564,33697,33831,33963,34095, 4321 34226,34357,34486,34616,34744,34873,35000,35127, 4322 35253,35379,35504,35629,35753,35876,35999,36122, 4323 36244,36365,36486,36606,36726,36845,36964,37083, 4324 37201,37318,37435,37551,37668,37783,37898,38013, 4325 38127,38241,38354,38467,38580,38692,38803,38915, 4326 39026,39136,39246,39356,39465,39574,39682,39790, 4327 39898,40005,40112,40219,40325,40431,40537,40642, 4328 40747,40851,40955,41059,41163,41266,41369,41471, 4329 41573,41675,41777,41878,41979,42079,42179,42279, 4330 42379,42478,42577,42676,42775,42873,42971,43068, 4331 43165,43262,43359,43456,43552,43648,43743,43839, 4332 43934,44028,44123,44217,44311,44405,44499,44592, 4333 44685,44778,44870,44962,45054,45146,45238,45329, 4334 45420,45511,45601,45692,45782,45872,45961,46051, 4335 46140,46229,46318,46406,46494,46583,46670,46758, 4336 46846,46933,47020,47107,47193,47280,47366,47452, 4337 47538,47623,47709,47794,47879,47964,48048,48133, 4338 48217,48301,48385,48468,48552,48635,48718,48801, 4339 48884,48966,49048,49131,49213,49294,49376,49458, 4340 49539,49620,49701,49782,49862,49943,50023,50103, 4341 50183,50263,50342,50422,50501,50580,50659,50738, 4342 50816,50895,50973,51051,51129,51207,51285,51362, 4343 51439,51517,51594,51671,51747,51824,51900,51977, 4344 52053,52129,52205,52280,52356,52432,52507,52582, 4345 52657,52732,52807,52881,52956,53030,53104,53178, 4346 53252,53326,53400,53473,53546,53620,53693,53766, 4347 53839,53911,53984,54056,54129,54201,54273,54345, 4348 54417,54489,54560,54632,54703,54774,54845,54916, 4349 54987,55058,55129,55199,55269,55340,55410,55480, 4350 55550,55620,55689,55759,55828,55898,55967,56036, 4351 56105,56174,56243,56311,56380,56448,56517,56585, 4352 56653,56721,56789,56857,56924,56992,57059,57127, 4353 57194,57261,57328,57395,57462,57529,57595,57662, 4354 57728,57795,57861,57927,57993,58059,58125,58191, 4355 58256,58322,58387,58453,58518,58583,58648,58713, 4356 58778,58843,58908,58972,59037,59101,59165,59230, 4357 59294,59358,59422,59486,59549,59613,59677,59740, 4358 59804,59867,59930,59993,60056,60119,60182,60245, 4359 60308,60370,60433,60495,60558,60620,60682,60744, 4360 60806,60868,60930,60992,61054,61115,61177,61238, 4361 61300,61361,61422,61483,61544,61605,61666,61727, 4362 61788,61848,61909,61969,62030,62090,62150,62211, 4363 62271,62331,62391,62450,62510,62570,62630,62689, 4364 62749,62808,62867,62927,62986,63045,63104,63163, 4365 63222,63281,63340,63398,63457,63515,63574,63632, 4366 63691,63749,63807,63865,63923,63981,64039,64097, 4367 64155,64212,64270,64328,64385,64443,64500,64557, 4368 64614,64672,64729,64786,64843,64900,64956,65013, 4369 65070,65126,65183,65239,65296,65352,65409,65465 4370}; 4371 4372const png_byte png_sRGB_delta[512] = 4373{ 4374 207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54, 4375 52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36, 4376 35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28, 4377 28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24, 4378 23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21, 4379 21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19, 4380 19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17, 4381 17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16, 4382 16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15, 4383 15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14, 4384 14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13, 4385 13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12, 4386 12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12, 4387 12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11, 4388 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11, 4389 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11, 4390 11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10, 4391 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10, 4392 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10, 4393 10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 4394 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 4395 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 4396 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 4397 9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 4398 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 4399 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 4400 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 4401 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 4402 8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7, 4403 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 4404 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 4405 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 4406}; 4407#endif /* SIMPLIFIED READ/WRITE sRGB support */ 4408 4409/* SIMPLIFIED READ/WRITE SUPPORT */ 4410#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\ 4411 defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) 4412static int 4413png_image_free_function(png_voidp argument) 4414{ 4415 png_imagep image = png_voidcast(png_imagep, argument); 4416 png_controlp cp = image->opaque; 4417 png_control c; 4418 4419 /* Double check that we have a png_ptr - it should be impossible to get here 4420 * without one. 4421 */ 4422 if (cp->png_ptr == NULL) 4423 return 0; 4424 4425 /* First free any data held in the control structure. */ 4426# ifdef PNG_STDIO_SUPPORTED 4427 if (cp->owned_file != 0) 4428 { 4429 FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr); 4430 cp->owned_file = 0; 4431 4432 /* Ignore errors here. */ 4433 if (fp != NULL) 4434 { 4435 cp->png_ptr->io_ptr = NULL; 4436 (void)fclose(fp); 4437 } 4438 } 4439# endif 4440 4441 /* Copy the control structure so that the original, allocated, version can be 4442 * safely freed. Notice that a png_error here stops the remainder of the 4443 * cleanup, but this is probably fine because that would indicate bad memory 4444 * problems anyway. 4445 */ 4446 c = *cp; 4447 image->opaque = &c; 4448 png_free(c.png_ptr, cp); 4449 4450 /* Then the structures, calling the correct API. */ 4451 if (c.for_write != 0) 4452 { 4453# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED 4454 png_destroy_write_struct(&c.png_ptr, &c.info_ptr); 4455# else 4456 png_error(c.png_ptr, "simplified write not supported"); 4457# endif 4458 } 4459 else 4460 { 4461# ifdef PNG_SIMPLIFIED_READ_SUPPORTED 4462 png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL); 4463# else 4464 png_error(c.png_ptr, "simplified read not supported"); 4465# endif 4466 } 4467 4468 /* Success. */ 4469 return 1; 4470} 4471 4472void PNGAPI 4473png_image_free(png_imagep image) 4474{ 4475 /* Safely call the real function, but only if doing so is safe at this point 4476 * (if not inside an error handling context). Otherwise assume 4477 * png_safe_execute will call this API after the return. 4478 */ 4479 if (image != NULL && image->opaque != NULL && 4480 image->opaque->error_buf == NULL) 4481 { 4482 /* Ignore errors here: */ 4483 (void)png_safe_execute(image, png_image_free_function, image); 4484 image->opaque = NULL; 4485 } 4486} 4487 4488int /* PRIVATE */ 4489png_image_error(png_imagep image, png_const_charp error_message) 4490{ 4491 /* Utility to log an error. */ 4492 png_safecat(image->message, (sizeof image->message), 0, error_message); 4493 image->warning_or_error |= PNG_IMAGE_ERROR; 4494 png_image_free(image); 4495 return 0; 4496} 4497 4498#endif /* SIMPLIFIED READ/WRITE */ 4499#endif /* READ || WRITE */ 4500