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Diffstat (limited to 'third_party/libpng/png.c')
| -rw-r--r-- | third_party/libpng/png.c | 4498 |
1 files changed, 0 insertions, 4498 deletions
diff --git a/third_party/libpng/png.c b/third_party/libpng/png.c deleted file mode 100644 index c183e3f8fa..0000000000 --- a/third_party/libpng/png.c +++ /dev/null @@ -1,4498 +0,0 @@ - -/* png.c - location for general purpose libpng functions - * - * Last changed in libpng 1.6.19 [November 12, 2015] - * Copyright (c) 1998-2015 Glenn Randers-Pehrson - * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) - * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) - * - * This code is released under the libpng license. - * For conditions of distribution and use, see the disclaimer - * and license in png.h - */ - -#include "pngpriv.h" - -/* Generate a compiler error if there is an old png.h in the search path. */ -typedef png_libpng_version_1_6_20 Your_png_h_is_not_version_1_6_20; - -/* Tells libpng that we have already handled the first "num_bytes" bytes - * of the PNG file signature. If the PNG data is embedded into another - * stream we can set num_bytes = 8 so that libpng will not attempt to read - * or write any of the magic bytes before it starts on the IHDR. - */ - -#ifdef PNG_READ_SUPPORTED -void PNGAPI -png_set_sig_bytes(png_structrp png_ptr, int num_bytes) -{ - unsigned int nb = (unsigned int)num_bytes; - - png_debug(1, "in png_set_sig_bytes"); - - if (png_ptr == NULL) - return; - - if (num_bytes < 0) - nb = 0; - - if (nb > 8) - png_error(png_ptr, "Too many bytes for PNG signature"); - - png_ptr->sig_bytes = (png_byte)nb; -} - -/* Checks whether the supplied bytes match the PNG signature. We allow - * checking less than the full 8-byte signature so that those apps that - * already read the first few bytes of a file to determine the file type - * can simply check the remaining bytes for extra assurance. Returns - * an integer less than, equal to, or greater than zero if sig is found, - * respectively, to be less than, to match, or be greater than the correct - * PNG signature (this is the same behavior as strcmp, memcmp, etc). - */ -int PNGAPI -png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check) -{ - png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; - - if (num_to_check > 8) - num_to_check = 8; - - else if (num_to_check < 1) - return (-1); - - if (start > 7) - return (-1); - - if (start + num_to_check > 8) - num_to_check = 8 - start; - - return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check))); -} - -#endif /* READ */ - -#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) -/* Function to allocate memory for zlib */ -PNG_FUNCTION(voidpf /* PRIVATE */, -png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED) -{ - png_alloc_size_t num_bytes = size; - - if (png_ptr == NULL) - return NULL; - - if (items >= (~(png_alloc_size_t)0)/size) - { - png_warning (png_voidcast(png_structrp, png_ptr), - "Potential overflow in png_zalloc()"); - return NULL; - } - - num_bytes *= items; - return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes); -} - -/* Function to free memory for zlib */ -void /* PRIVATE */ -png_zfree(voidpf png_ptr, voidpf ptr) -{ - png_free(png_voidcast(png_const_structrp,png_ptr), ptr); -} - -/* Reset the CRC variable to 32 bits of 1's. Care must be taken - * in case CRC is > 32 bits to leave the top bits 0. - */ -void /* PRIVATE */ -png_reset_crc(png_structrp png_ptr) -{ - /* The cast is safe because the crc is a 32-bit value. */ - png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0); -} - -/* Calculate the CRC over a section of data. We can only pass as - * much data to this routine as the largest single buffer size. We - * also check that this data will actually be used before going to the - * trouble of calculating it. - */ -void /* PRIVATE */ -png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length) -{ - int need_crc = 1; - - if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0) - { - if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) == - (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN)) - need_crc = 0; - } - - else /* critical */ - { - if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0) - need_crc = 0; - } - - /* 'uLong' is defined in zlib.h as unsigned long; this means that on some - * systems it is a 64-bit value. crc32, however, returns 32 bits so the - * following cast is safe. 'uInt' may be no more than 16 bits, so it is - * necessary to perform a loop here. - */ - if (need_crc != 0 && length > 0) - { - uLong crc = png_ptr->crc; /* Should never issue a warning */ - - do - { - uInt safe_length = (uInt)length; -#ifndef __COVERITY__ - if (safe_length == 0) - safe_length = (uInt)-1; /* evil, but safe */ -#endif - - crc = crc32(crc, ptr, safe_length); - - /* The following should never issue compiler warnings; if they do the - * target system has characteristics that will probably violate other - * assumptions within the libpng code. - */ - ptr += safe_length; - length -= safe_length; - } - while (length > 0); - - /* And the following is always safe because the crc is only 32 bits. */ - png_ptr->crc = (png_uint_32)crc; - } -} - -/* Check a user supplied version number, called from both read and write - * functions that create a png_struct. - */ -int -png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver) -{ - /* Libpng versions 1.0.0 and later are binary compatible if the version - * string matches through the second '.'; we must recompile any - * applications that use any older library version. - */ - - if (user_png_ver != NULL) - { - int i = -1; - int found_dots = 0; - - do - { - i++; - if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i]) - png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; - if (user_png_ver[i] == '.') - found_dots++; - } while (found_dots < 2 && user_png_ver[i] != 0 && - PNG_LIBPNG_VER_STRING[i] != 0); - } - - else - png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; - - if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0) - { -#ifdef PNG_WARNINGS_SUPPORTED - size_t pos = 0; - char m[128]; - - pos = png_safecat(m, (sizeof m), pos, - "Application built with libpng-"); - pos = png_safecat(m, (sizeof m), pos, user_png_ver); - pos = png_safecat(m, (sizeof m), pos, " but running with "); - pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING); - PNG_UNUSED(pos) - - png_warning(png_ptr, m); -#endif - -#ifdef PNG_ERROR_NUMBERS_SUPPORTED - png_ptr->flags = 0; -#endif - - return 0; - } - - /* Success return. */ - return 1; -} - -/* Generic function to create a png_struct for either read or write - this - * contains the common initialization. - */ -PNG_FUNCTION(png_structp /* PRIVATE */, -png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr, - png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, - png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED) -{ - png_struct create_struct; -# ifdef PNG_SETJMP_SUPPORTED - jmp_buf create_jmp_buf; -# endif - - /* This temporary stack-allocated structure is used to provide a place to - * build enough context to allow the user provided memory allocator (if any) - * to be called. - */ - memset(&create_struct, 0, (sizeof create_struct)); - - /* Added at libpng-1.2.6 */ -# ifdef PNG_USER_LIMITS_SUPPORTED - create_struct.user_width_max = PNG_USER_WIDTH_MAX; - create_struct.user_height_max = PNG_USER_HEIGHT_MAX; - -# ifdef PNG_USER_CHUNK_CACHE_MAX - /* Added at libpng-1.2.43 and 1.4.0 */ - create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX; -# endif - -# ifdef PNG_USER_CHUNK_MALLOC_MAX - /* Added at libpng-1.2.43 and 1.4.1, required only for read but exists - * in png_struct regardless. - */ - create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX; -# endif -# endif - - /* The following two API calls simply set fields in png_struct, so it is safe - * to do them now even though error handling is not yet set up. - */ -# ifdef PNG_USER_MEM_SUPPORTED - png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn); -# else - PNG_UNUSED(mem_ptr) - PNG_UNUSED(malloc_fn) - PNG_UNUSED(free_fn) -# endif - - /* (*error_fn) can return control to the caller after the error_ptr is set, - * this will result in a memory leak unless the error_fn does something - * extremely sophisticated. The design lacks merit but is implicit in the - * API. - */ - png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn); - -# ifdef PNG_SETJMP_SUPPORTED - if (!setjmp(create_jmp_buf)) -# endif - { -# ifdef PNG_SETJMP_SUPPORTED - /* Temporarily fake out the longjmp information until we have - * successfully completed this function. This only works if we have - * setjmp() support compiled in, but it is safe - this stuff should - * never happen. - */ - create_struct.jmp_buf_ptr = &create_jmp_buf; - create_struct.jmp_buf_size = 0; /*stack allocation*/ - create_struct.longjmp_fn = longjmp; -# endif - /* Call the general version checker (shared with read and write code): - */ - if (png_user_version_check(&create_struct, user_png_ver) != 0) - { - png_structrp png_ptr = png_voidcast(png_structrp, - png_malloc_warn(&create_struct, (sizeof *png_ptr))); - - if (png_ptr != NULL) - { - /* png_ptr->zstream holds a back-pointer to the png_struct, so - * this can only be done now: - */ - create_struct.zstream.zalloc = png_zalloc; - create_struct.zstream.zfree = png_zfree; - create_struct.zstream.opaque = png_ptr; - -# ifdef PNG_SETJMP_SUPPORTED - /* Eliminate the local error handling: */ - create_struct.jmp_buf_ptr = NULL; - create_struct.jmp_buf_size = 0; - create_struct.longjmp_fn = 0; -# endif - - *png_ptr = create_struct; - - /* This is the successful return point */ - return png_ptr; - } - } - } - - /* A longjmp because of a bug in the application storage allocator or a - * simple failure to allocate the png_struct. - */ - return NULL; -} - -/* Allocate the memory for an info_struct for the application. */ -PNG_FUNCTION(png_infop,PNGAPI -png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED) -{ - png_inforp info_ptr; - - png_debug(1, "in png_create_info_struct"); - - if (png_ptr == NULL) - return NULL; - - /* Use the internal API that does not (or at least should not) error out, so - * that this call always returns ok. The application typically sets up the - * error handling *after* creating the info_struct because this is the way it - * has always been done in 'example.c'. - */ - info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr, - (sizeof *info_ptr))); - - if (info_ptr != NULL) - memset(info_ptr, 0, (sizeof *info_ptr)); - - return info_ptr; -} - -/* This function frees the memory associated with a single info struct. - * Normally, one would use either png_destroy_read_struct() or - * png_destroy_write_struct() to free an info struct, but this may be - * useful for some applications. From libpng 1.6.0 this function is also used - * internally to implement the png_info release part of the 'struct' destroy - * APIs. This ensures that all possible approaches free the same data (all of - * it). - */ -void PNGAPI -png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr) -{ - png_inforp info_ptr = NULL; - - png_debug(1, "in png_destroy_info_struct"); - - if (png_ptr == NULL) - return; - - if (info_ptr_ptr != NULL) - info_ptr = *info_ptr_ptr; - - if (info_ptr != NULL) - { - /* Do this first in case of an error below; if the app implements its own - * memory management this can lead to png_free calling png_error, which - * will abort this routine and return control to the app error handler. - * An infinite loop may result if it then tries to free the same info - * ptr. - */ - *info_ptr_ptr = NULL; - - png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1); - memset(info_ptr, 0, (sizeof *info_ptr)); - png_free(png_ptr, info_ptr); - } -} - -/* Initialize the info structure. This is now an internal function (0.89) - * and applications using it are urged to use png_create_info_struct() - * instead. Use deprecated in 1.6.0, internal use removed (used internally it - * is just a memset). - * - * NOTE: it is almost inconceivable that this API is used because it bypasses - * the user-memory mechanism and the user error handling/warning mechanisms in - * those cases where it does anything other than a memset. - */ -PNG_FUNCTION(void,PNGAPI -png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size), - PNG_DEPRECATED) -{ - png_inforp info_ptr = *ptr_ptr; - - png_debug(1, "in png_info_init_3"); - - if (info_ptr == NULL) - return; - - if ((sizeof (png_info)) > png_info_struct_size) - { - *ptr_ptr = NULL; - /* The following line is why this API should not be used: */ - free(info_ptr); - info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL, - (sizeof *info_ptr))); - if (info_ptr == NULL) - return; - *ptr_ptr = info_ptr; - } - - /* Set everything to 0 */ - memset(info_ptr, 0, (sizeof *info_ptr)); -} - -/* The following API is not called internally */ -void PNGAPI -png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr, - int freer, png_uint_32 mask) -{ - png_debug(1, "in png_data_freer"); - - if (png_ptr == NULL || info_ptr == NULL) - return; - - if (freer == PNG_DESTROY_WILL_FREE_DATA) - info_ptr->free_me |= mask; - - else if (freer == PNG_USER_WILL_FREE_DATA) - info_ptr->free_me &= ~mask; - - else - png_error(png_ptr, "Unknown freer parameter in png_data_freer"); -} - -void PNGAPI -png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask, - int num) -{ - png_debug(1, "in png_free_data"); - - if (png_ptr == NULL || info_ptr == NULL) - return; - -#ifdef PNG_TEXT_SUPPORTED - /* Free text item num or (if num == -1) all text items */ - if (info_ptr->text != 0 && - ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0) - { - if (num != -1) - { - png_free(png_ptr, info_ptr->text[num].key); - info_ptr->text[num].key = NULL; - } - - else - { - int i; - - for (i = 0; i < info_ptr->num_text; i++) - png_free(png_ptr, info_ptr->text[i].key); - - png_free(png_ptr, info_ptr->text); - info_ptr->text = NULL; - info_ptr->num_text = 0; - } - } -#endif - -#ifdef PNG_tRNS_SUPPORTED - /* Free any tRNS entry */ - if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0) - { - info_ptr->valid &= ~PNG_INFO_tRNS; - png_free(png_ptr, info_ptr->trans_alpha); - info_ptr->trans_alpha = NULL; - info_ptr->num_trans = 0; - } -#endif - -#ifdef PNG_sCAL_SUPPORTED - /* Free any sCAL entry */ - if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0) - { - png_free(png_ptr, info_ptr->scal_s_width); - png_free(png_ptr, info_ptr->scal_s_height); - info_ptr->scal_s_width = NULL; - info_ptr->scal_s_height = NULL; - info_ptr->valid &= ~PNG_INFO_sCAL; - } -#endif - -#ifdef PNG_pCAL_SUPPORTED - /* Free any pCAL entry */ - if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0) - { - png_free(png_ptr, info_ptr->pcal_purpose); - png_free(png_ptr, info_ptr->pcal_units); - info_ptr->pcal_purpose = NULL; - info_ptr->pcal_units = NULL; - - if (info_ptr->pcal_params != NULL) - { - int i; - - for (i = 0; i < info_ptr->pcal_nparams; i++) - png_free(png_ptr, info_ptr->pcal_params[i]); - - png_free(png_ptr, info_ptr->pcal_params); - info_ptr->pcal_params = NULL; - } - info_ptr->valid &= ~PNG_INFO_pCAL; - } -#endif - -#ifdef PNG_iCCP_SUPPORTED - /* Free any profile entry */ - if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0) - { - png_free(png_ptr, info_ptr->iccp_name); - png_free(png_ptr, info_ptr->iccp_profile); - info_ptr->iccp_name = NULL; - info_ptr->iccp_profile = NULL; - info_ptr->valid &= ~PNG_INFO_iCCP; - } -#endif - -#ifdef PNG_sPLT_SUPPORTED - /* Free a given sPLT entry, or (if num == -1) all sPLT entries */ - if (info_ptr->splt_palettes != 0 && - ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0) - { - if (num != -1) - { - png_free(png_ptr, info_ptr->splt_palettes[num].name); - png_free(png_ptr, info_ptr->splt_palettes[num].entries); - info_ptr->splt_palettes[num].name = NULL; - info_ptr->splt_palettes[num].entries = NULL; - } - - else - { - int i; - - for (i = 0; i < info_ptr->splt_palettes_num; i++) - { - png_free(png_ptr, info_ptr->splt_palettes[i].name); - png_free(png_ptr, info_ptr->splt_palettes[i].entries); - } - - png_free(png_ptr, info_ptr->splt_palettes); - info_ptr->splt_palettes = NULL; - info_ptr->splt_palettes_num = 0; - info_ptr->valid &= ~PNG_INFO_sPLT; - } - } -#endif - -#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED - if (info_ptr->unknown_chunks != 0 && - ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0) - { - if (num != -1) - { - png_free(png_ptr, info_ptr->unknown_chunks[num].data); - info_ptr->unknown_chunks[num].data = NULL; - } - - else - { - int i; - - for (i = 0; i < info_ptr->unknown_chunks_num; i++) - png_free(png_ptr, info_ptr->unknown_chunks[i].data); - - png_free(png_ptr, info_ptr->unknown_chunks); - info_ptr->unknown_chunks = NULL; - info_ptr->unknown_chunks_num = 0; - } - } -#endif - -#ifdef PNG_hIST_SUPPORTED - /* Free any hIST entry */ - if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0) - { - png_free(png_ptr, info_ptr->hist); - info_ptr->hist = NULL; - info_ptr->valid &= ~PNG_INFO_hIST; - } -#endif - - /* Free any PLTE entry that was internally allocated */ - if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0) - { - png_free(png_ptr, info_ptr->palette); - info_ptr->palette = NULL; - info_ptr->valid &= ~PNG_INFO_PLTE; - info_ptr->num_palette = 0; - } - -#ifdef PNG_INFO_IMAGE_SUPPORTED - /* Free any image bits attached to the info structure */ - if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0) - { - if (info_ptr->row_pointers != 0) - { - png_uint_32 row; - for (row = 0; row < info_ptr->height; row++) - png_free(png_ptr, info_ptr->row_pointers[row]); - - png_free(png_ptr, info_ptr->row_pointers); - info_ptr->row_pointers = NULL; - } - info_ptr->valid &= ~PNG_INFO_IDAT; - } -#endif - - if (num != -1) - mask &= ~PNG_FREE_MUL; - - info_ptr->free_me &= ~mask; -} -#endif /* READ || WRITE */ - -/* This function returns a pointer to the io_ptr associated with the user - * functions. The application should free any memory associated with this - * pointer before png_write_destroy() or png_read_destroy() are called. - */ -png_voidp PNGAPI -png_get_io_ptr(png_const_structrp png_ptr) -{ - if (png_ptr == NULL) - return (NULL); - - return (png_ptr->io_ptr); -} - -#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) -# ifdef PNG_STDIO_SUPPORTED -/* Initialize the default input/output functions for the PNG file. If you - * use your own read or write routines, you can call either png_set_read_fn() - * or png_set_write_fn() instead of png_init_io(). If you have defined - * PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a - * function of your own because "FILE *" isn't necessarily available. - */ -void PNGAPI -png_init_io(png_structrp png_ptr, png_FILE_p fp) -{ - png_debug(1, "in png_init_io"); - - if (png_ptr == NULL) - return; - - png_ptr->io_ptr = (png_voidp)fp; -} -# endif - -# ifdef PNG_SAVE_INT_32_SUPPORTED -/* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90 - * defines a cast of a signed integer to an unsigned integer either to preserve - * the value, if it is positive, or to calculate: - * - * (UNSIGNED_MAX+1) + integer - * - * Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the - * negative integral value is added the result will be an unsigned value - * correspnding to the 2's complement representation. - */ -void PNGAPI -png_save_int_32(png_bytep buf, png_int_32 i) -{ - png_save_uint_32(buf, i); -} -# endif - -# ifdef PNG_TIME_RFC1123_SUPPORTED -/* Convert the supplied time into an RFC 1123 string suitable for use in - * a "Creation Time" or other text-based time string. - */ -int PNGAPI -png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime) -{ - static PNG_CONST char short_months[12][4] = - {"Jan", "Feb", "Mar", "Apr", "May", "Jun", - "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; - - if (out == NULL) - return 0; - - if (ptime->year > 9999 /* RFC1123 limitation */ || - ptime->month == 0 || ptime->month > 12 || - ptime->day == 0 || ptime->day > 31 || - ptime->hour > 23 || ptime->minute > 59 || - ptime->second > 60) - return 0; - - { - size_t pos = 0; - char number_buf[5]; /* enough for a four-digit year */ - -# define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string)) -# define APPEND_NUMBER(format, value)\ - APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value))) -# define APPEND(ch) if (pos < 28) out[pos++] = (ch) - - APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day); - APPEND(' '); - APPEND_STRING(short_months[(ptime->month - 1)]); - APPEND(' '); - APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year); - APPEND(' '); - APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour); - APPEND(':'); - APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute); - APPEND(':'); - APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second); - APPEND_STRING(" +0000"); /* This reliably terminates the buffer */ - PNG_UNUSED (pos) - -# undef APPEND -# undef APPEND_NUMBER -# undef APPEND_STRING - } - - return 1; -} - -# if PNG_LIBPNG_VER < 10700 -/* To do: remove the following from libpng-1.7 */ -/* Original API that uses a private buffer in png_struct. - * Deprecated because it causes png_struct to carry a spurious temporary - * buffer (png_struct::time_buffer), better to have the caller pass this in. - */ -png_const_charp PNGAPI -png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime) -{ - if (png_ptr != NULL) - { - /* The only failure above if png_ptr != NULL is from an invalid ptime */ - if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0) - png_warning(png_ptr, "Ignoring invalid time value"); - - else - return png_ptr->time_buffer; - } - - return NULL; -} -# endif /* LIBPNG_VER < 10700 */ -# endif /* TIME_RFC1123 */ - -#endif /* READ || WRITE */ - -png_const_charp PNGAPI -png_get_copyright(png_const_structrp png_ptr) -{ - PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ -#ifdef PNG_STRING_COPYRIGHT - return PNG_STRING_COPYRIGHT -#else -# ifdef __STDC__ - return PNG_STRING_NEWLINE \ - "libpng version 1.6.20 - December 3, 2015" PNG_STRING_NEWLINE \ - "Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \ - "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \ - "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \ - PNG_STRING_NEWLINE; -# else - return "libpng version 1.6.20 - December 3, 2015\ - Copyright (c) 1998-2015 Glenn Randers-Pehrson\ - Copyright (c) 1996-1997 Andreas Dilger\ - Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc."; -# endif -#endif -} - -/* The following return the library version as a short string in the - * format 1.0.0 through 99.99.99zz. To get the version of *.h files - * used with your application, print out PNG_LIBPNG_VER_STRING, which - * is defined in png.h. - * Note: now there is no difference between png_get_libpng_ver() and - * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard, - * it is guaranteed that png.c uses the correct version of png.h. - */ -png_const_charp PNGAPI -png_get_libpng_ver(png_const_structrp png_ptr) -{ - /* Version of *.c files used when building libpng */ - return png_get_header_ver(png_ptr); -} - -png_const_charp PNGAPI -png_get_header_ver(png_const_structrp png_ptr) -{ - /* Version of *.h files used when building libpng */ - PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ - return PNG_LIBPNG_VER_STRING; -} - -png_const_charp PNGAPI -png_get_header_version(png_const_structrp png_ptr) -{ - /* Returns longer string containing both version and date */ - PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ -#ifdef __STDC__ - return PNG_HEADER_VERSION_STRING -# ifndef PNG_READ_SUPPORTED - " (NO READ SUPPORT)" -# endif - PNG_STRING_NEWLINE; -#else - return PNG_HEADER_VERSION_STRING; -#endif -} - -#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED -/* NOTE: this routine is not used internally! */ -/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth - * large of png_color. This lets grayscale images be treated as - * paletted. Most useful for gamma correction and simplification - * of code. This API is not used internally. - */ -void PNGAPI -png_build_grayscale_palette(int bit_depth, png_colorp palette) -{ - int num_palette; - int color_inc; - int i; - int v; - - png_debug(1, "in png_do_build_grayscale_palette"); - - if (palette == NULL) - return; - - switch (bit_depth) - { - case 1: - num_palette = 2; - color_inc = 0xff; - break; - - case 2: - num_palette = 4; - color_inc = 0x55; - break; - - case 4: - num_palette = 16; - color_inc = 0x11; - break; - - case 8: - num_palette = 256; - color_inc = 1; - break; - - default: - num_palette = 0; - color_inc = 0; - break; - } - - for (i = 0, v = 0; i < num_palette; i++, v += color_inc) - { - palette[i].red = (png_byte)(v & 0xff); - palette[i].green = (png_byte)(v & 0xff); - palette[i].blue = (png_byte)(v & 0xff); - } -} -#endif - -#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED -int PNGAPI -png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name) -{ - /* Check chunk_name and return "keep" value if it's on the list, else 0 */ - png_const_bytep p, p_end; - - if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0) - return PNG_HANDLE_CHUNK_AS_DEFAULT; - - p_end = png_ptr->chunk_list; - p = p_end + png_ptr->num_chunk_list*5; /* beyond end */ - - /* The code is the fifth byte after each four byte string. Historically this - * code was always searched from the end of the list, this is no longer - * necessary because the 'set' routine handles duplicate entries correcty. - */ - do /* num_chunk_list > 0, so at least one */ - { - p -= 5; - - if (memcmp(chunk_name, p, 4) == 0) - return p[4]; - } - while (p > p_end); - - /* This means that known chunks should be processed and unknown chunks should - * be handled according to the value of png_ptr->unknown_default; this can be - * confusing because, as a result, there are two levels of defaulting for - * unknown chunks. - */ - return PNG_HANDLE_CHUNK_AS_DEFAULT; -} - -#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\ - defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED) -int /* PRIVATE */ -png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name) -{ - png_byte chunk_string[5]; - - PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name); - return png_handle_as_unknown(png_ptr, chunk_string); -} -#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */ -#endif /* SET_UNKNOWN_CHUNKS */ - -#ifdef PNG_READ_SUPPORTED -/* This function, added to libpng-1.0.6g, is untested. */ -int PNGAPI -png_reset_zstream(png_structrp png_ptr) -{ - if (png_ptr == NULL) - return Z_STREAM_ERROR; - - /* WARNING: this resets the window bits to the maximum! */ - return (inflateReset(&png_ptr->zstream)); -} -#endif /* READ */ - -/* This function was added to libpng-1.0.7 */ -png_uint_32 PNGAPI -png_access_version_number(void) -{ - /* Version of *.c files used when building libpng */ - return((png_uint_32)PNG_LIBPNG_VER); -} - -#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) -/* Ensure that png_ptr->zstream.msg holds some appropriate error message string. - * If it doesn't 'ret' is used to set it to something appropriate, even in cases - * like Z_OK or Z_STREAM_END where the error code is apparently a success code. - */ -void /* PRIVATE */ -png_zstream_error(png_structrp png_ptr, int ret) -{ - /* Translate 'ret' into an appropriate error string, priority is given to the - * one in zstream if set. This always returns a string, even in cases like - * Z_OK or Z_STREAM_END where the error code is a success code. - */ - if (png_ptr->zstream.msg == NULL) switch (ret) - { - default: - case Z_OK: - png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code"); - break; - - case Z_STREAM_END: - /* Normal exit */ - png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream"); - break; - - case Z_NEED_DICT: - /* This means the deflate stream did not have a dictionary; this - * indicates a bogus PNG. - */ - png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary"); - break; - - case Z_ERRNO: - /* gz APIs only: should not happen */ - png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error"); - break; - - case Z_STREAM_ERROR: - /* internal libpng error */ - png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib"); - break; - - case Z_DATA_ERROR: - png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream"); - break; - - case Z_MEM_ERROR: - png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory"); - break; - - case Z_BUF_ERROR: - /* End of input or output; not a problem if the caller is doing - * incremental read or write. - */ - png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated"); - break; - - case Z_VERSION_ERROR: - png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version"); - break; - - case PNG_UNEXPECTED_ZLIB_RETURN: - /* Compile errors here mean that zlib now uses the value co-opted in - * pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above - * and change pngpriv.h. Note that this message is "... return", - * whereas the default/Z_OK one is "... return code". - */ - png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return"); - break; - } -} - -/* png_convert_size: a PNGAPI but no longer in png.h, so deleted - * at libpng 1.5.5! - */ - -/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */ -#ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */ -static int -png_colorspace_check_gamma(png_const_structrp png_ptr, - png_colorspacerp colorspace, png_fixed_point gAMA, int from) - /* This is called to check a new gamma value against an existing one. The - * routine returns false if the new gamma value should not be written. - * - * 'from' says where the new gamma value comes from: - * - * 0: the new gamma value is the libpng estimate for an ICC profile - * 1: the new gamma value comes from a gAMA chunk - * 2: the new gamma value comes from an sRGB chunk - */ -{ - png_fixed_point gtest; - - if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 && - (png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) == 0 || - png_gamma_significant(gtest) != 0)) - { - /* Either this is an sRGB image, in which case the calculated gamma - * approximation should match, or this is an image with a profile and the - * value libpng calculates for the gamma of the profile does not match the - * value recorded in the file. The former, sRGB, case is an error, the - * latter is just a warning. - */ - if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2) - { - png_chunk_report(png_ptr, "gamma value does not match sRGB", - PNG_CHUNK_ERROR); - /* Do not overwrite an sRGB value */ - return from == 2; - } - - else /* sRGB tag not involved */ - { - png_chunk_report(png_ptr, "gamma value does not match libpng estimate", - PNG_CHUNK_WARNING); - return from == 1; - } - } - - return 1; -} - -void /* PRIVATE */ -png_colorspace_set_gamma(png_const_structrp png_ptr, - png_colorspacerp colorspace, png_fixed_point gAMA) -{ - /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't - * occur. Since the fixed point representation is asymetrical it is - * possible for 1/gamma to overflow the limit of 21474 and this means the - * gamma value must be at least 5/100000 and hence at most 20000.0. For - * safety the limits here are a little narrower. The values are 0.00016 to - * 6250.0, which are truly ridiculous gamma values (and will produce - * displays that are all black or all white.) - * - * In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk - * handling code, which only required the value to be >0. - */ - png_const_charp errmsg; - - if (gAMA < 16 || gAMA > 625000000) - errmsg = "gamma value out of range"; - -# ifdef PNG_READ_gAMA_SUPPORTED - /* Allow the application to set the gamma value more than once */ - else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 && - (colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0) - errmsg = "duplicate"; -# endif - - /* Do nothing if the colorspace is already invalid */ - else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0) - return; - - else - { - if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA, - 1/*from gAMA*/) != 0) - { - /* Store this gamma value. */ - colorspace->gamma = gAMA; - colorspace->flags |= - (PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA); - } - - /* At present if the check_gamma test fails the gamma of the colorspace is - * not updated however the colorspace is not invalidated. This - * corresponds to the case where the existing gamma comes from an sRGB - * chunk or profile. An error message has already been output. - */ - return; - } - - /* Error exit - errmsg has been set. */ - colorspace->flags |= PNG_COLORSPACE_INVALID; - png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR); -} - -void /* PRIVATE */ -png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr) -{ - if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0) - { - /* Everything is invalid */ - info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB| - PNG_INFO_iCCP); - -# ifdef PNG_COLORSPACE_SUPPORTED - /* Clean up the iCCP profile now if it won't be used. */ - png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/); -# else - PNG_UNUSED(png_ptr) -# endif - } - - else - { -# ifdef PNG_COLORSPACE_SUPPORTED - /* Leave the INFO_iCCP flag set if the pngset.c code has already set - * it; this allows a PNG to contain a profile which matches sRGB and - * yet still have that profile retrievable by the application. - */ - if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0) - info_ptr->valid |= PNG_INFO_sRGB; - - else - info_ptr->valid &= ~PNG_INFO_sRGB; - - if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0) - info_ptr->valid |= PNG_INFO_cHRM; - - else - info_ptr->valid &= ~PNG_INFO_cHRM; -# endif - - if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0) - info_ptr->valid |= PNG_INFO_gAMA; - - else - info_ptr->valid &= ~PNG_INFO_gAMA; - } -} - -#ifdef PNG_READ_SUPPORTED -void /* PRIVATE */ -png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr) -{ - if (info_ptr == NULL) /* reduce code size; check here not in the caller */ - return; - - info_ptr->colorspace = png_ptr->colorspace; - png_colorspace_sync_info(png_ptr, info_ptr); -} -#endif -#endif /* GAMMA */ - -#ifdef PNG_COLORSPACE_SUPPORTED -/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for - * cHRM, as opposed to using chromaticities. These internal APIs return - * non-zero on a parameter error. The X, Y and Z values are required to be - * positive and less than 1.0. - */ -static int -png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ) -{ - png_int_32 d, dwhite, whiteX, whiteY; - - d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z; - if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0) - return 1; - if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0) - return 1; - dwhite = d; - whiteX = XYZ->red_X; - whiteY = XYZ->red_Y; - - d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z; - if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0) - return 1; - if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0) - return 1; - dwhite += d; - whiteX += XYZ->green_X; - whiteY += XYZ->green_Y; - - d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z; - if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0) - return 1; - if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0) - return 1; - dwhite += d; - whiteX += XYZ->blue_X; - whiteY += XYZ->blue_Y; - - /* The reference white is simply the sum of the end-point (X,Y,Z) vectors, - * thus: - */ - if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0) - return 1; - if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0) - return 1; - - return 0; -} - -static int -png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy) -{ - png_fixed_point red_inverse, green_inverse, blue_scale; - png_fixed_point left, right, denominator; - - /* Check xy and, implicitly, z. Note that wide gamut color spaces typically - * have end points with 0 tristimulus values (these are impossible end - * points, but they are used to cover the possible colors). We check - * xy->whitey against 5, not 0, to avoid a possible integer overflow. - */ - if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1; - if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1; - if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1; - if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1; - if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1; - if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1; - if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1; - if (xy->whitey < 5 || xy->whitey > PNG_FP_1-xy->whitex) return 1; - - /* The reverse calculation is more difficult because the original tristimulus - * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8 - * derived values were recorded in the cHRM chunk; - * (red,green,blue,white)x(x,y). This loses one degree of freedom and - * therefore an arbitrary ninth value has to be introduced to undo the - * original transformations. - * - * Think of the original end-points as points in (X,Y,Z) space. The - * chromaticity values (c) have the property: - * - * C - * c = --------- - * X + Y + Z - * - * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the - * three chromaticity values (x,y,z) for each end-point obey the - * relationship: - * - * x + y + z = 1 - * - * This describes the plane in (X,Y,Z) space that intersects each axis at the - * value 1.0; call this the chromaticity plane. Thus the chromaticity - * calculation has scaled each end-point so that it is on the x+y+z=1 plane - * and chromaticity is the intersection of the vector from the origin to the - * (X,Y,Z) value with the chromaticity plane. - * - * To fully invert the chromaticity calculation we would need the three - * end-point scale factors, (red-scale, green-scale, blue-scale), but these - * were not recorded. Instead we calculated the reference white (X,Y,Z) and - * recorded the chromaticity of this. The reference white (X,Y,Z) would have - * given all three of the scale factors since: - * - * color-C = color-c * color-scale - * white-C = red-C + green-C + blue-C - * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale - * - * But cHRM records only white-x and white-y, so we have lost the white scale - * factor: - * - * white-C = white-c*white-scale - * - * To handle this the inverse transformation makes an arbitrary assumption - * about white-scale: - * - * Assume: white-Y = 1.0 - * Hence: white-scale = 1/white-y - * Or: red-Y + green-Y + blue-Y = 1.0 - * - * Notice the last statement of the assumption gives an equation in three of - * the nine values we want to calculate. 8 more equations come from the - * above routine as summarised at the top above (the chromaticity - * calculation): - * - * Given: color-x = color-X / (color-X + color-Y + color-Z) - * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0 - * - * This is 9 simultaneous equations in the 9 variables "color-C" and can be - * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix - * determinants, however this is not as bad as it seems because only 28 of - * the total of 90 terms in the various matrices are non-zero. Nevertheless - * Cramer's rule is notoriously numerically unstable because the determinant - * calculation involves the difference of large, but similar, numbers. It is - * difficult to be sure that the calculation is stable for real world values - * and it is certain that it becomes unstable where the end points are close - * together. - * - * So this code uses the perhaps slightly less optimal but more - * understandable and totally obvious approach of calculating color-scale. - * - * This algorithm depends on the precision in white-scale and that is - * (1/white-y), so we can immediately see that as white-y approaches 0 the - * accuracy inherent in the cHRM chunk drops off substantially. - * - * libpng arithmetic: a simple inversion of the above equations - * ------------------------------------------------------------ - * - * white_scale = 1/white-y - * white-X = white-x * white-scale - * white-Y = 1.0 - * white-Z = (1 - white-x - white-y) * white_scale - * - * white-C = red-C + green-C + blue-C - * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale - * - * This gives us three equations in (red-scale,green-scale,blue-scale) where - * all the coefficients are now known: - * - * red-x*red-scale + green-x*green-scale + blue-x*blue-scale - * = white-x/white-y - * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1 - * red-z*red-scale + green-z*green-scale + blue-z*blue-scale - * = (1 - white-x - white-y)/white-y - * - * In the last equation color-z is (1 - color-x - color-y) so we can add all - * three equations together to get an alternative third: - * - * red-scale + green-scale + blue-scale = 1/white-y = white-scale - * - * So now we have a Cramer's rule solution where the determinants are just - * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve - * multiplication of three coefficients so we can't guarantee to avoid - * overflow in the libpng fixed point representation. Using Cramer's rule in - * floating point is probably a good choice here, but it's not an option for - * fixed point. Instead proceed to simplify the first two equations by - * eliminating what is likely to be the largest value, blue-scale: - * - * blue-scale = white-scale - red-scale - green-scale - * - * Hence: - * - * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale = - * (white-x - blue-x)*white-scale - * - * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale = - * 1 - blue-y*white-scale - * - * And now we can trivially solve for (red-scale,green-scale): - * - * green-scale = - * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale - * ----------------------------------------------------------- - * green-x - blue-x - * - * red-scale = - * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale - * --------------------------------------------------------- - * red-y - blue-y - * - * Hence: - * - * red-scale = - * ( (green-x - blue-x) * (white-y - blue-y) - - * (green-y - blue-y) * (white-x - blue-x) ) / white-y - * ------------------------------------------------------------------------- - * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x) - * - * green-scale = - * ( (red-y - blue-y) * (white-x - blue-x) - - * (red-x - blue-x) * (white-y - blue-y) ) / white-y - * ------------------------------------------------------------------------- - * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x) - * - * Accuracy: - * The input values have 5 decimal digits of accuracy. The values are all in - * the range 0 < value < 1, so simple products are in the same range but may - * need up to 10 decimal digits to preserve the original precision and avoid - * underflow. Because we are using a 32-bit signed representation we cannot - * match this; the best is a little over 9 decimal digits, less than 10. - * - * The approach used here is to preserve the maximum precision within the - * signed representation. Because the red-scale calculation above uses the - * difference between two products of values that must be in the range -1..+1 - * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The - * factor is irrelevant in the calculation because it is applied to both - * numerator and denominator. - * - * Note that the values of the differences of the products of the - * chromaticities in the above equations tend to be small, for example for - * the sRGB chromaticities they are: - * - * red numerator: -0.04751 - * green numerator: -0.08788 - * denominator: -0.2241 (without white-y multiplication) - * - * The resultant Y coefficients from the chromaticities of some widely used - * color space definitions are (to 15 decimal places): - * - * sRGB - * 0.212639005871510 0.715168678767756 0.072192315360734 - * Kodak ProPhoto - * 0.288071128229293 0.711843217810102 0.000085653960605 - * Adobe RGB - * 0.297344975250536 0.627363566255466 0.075291458493998 - * Adobe Wide Gamut RGB - * 0.258728243040113 0.724682314948566 0.016589442011321 - */ - /* By the argument, above overflow should be impossible here. The return - * value of 2 indicates an internal error to the caller. - */ - if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0) - return 2; - if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0) - return 2; - denominator = left - right; - - /* Now find the red numerator. */ - if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0) - return 2; - if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0) - return 2; - - /* Overflow is possible here and it indicates an extreme set of PNG cHRM - * chunk values. This calculation actually returns the reciprocal of the - * scale value because this allows us to delay the multiplication of white-y - * into the denominator, which tends to produce a small number. - */ - if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 || - red_inverse <= xy->whitey /* r+g+b scales = white scale */) - return 1; - - /* Similarly for green_inverse: */ - if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0) - return 2; - if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0) - return 2; - if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 || - green_inverse <= xy->whitey) - return 1; - - /* And the blue scale, the checks above guarantee this can't overflow but it - * can still produce 0 for extreme cHRM values. - */ - blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) - - png_reciprocal(green_inverse); - if (blue_scale <= 0) - return 1; - - - /* And fill in the png_XYZ: */ - if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0) - return 1; - if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0) - return 1; - if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1, - red_inverse) == 0) - return 1; - - if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0) - return 1; - if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0) - return 1; - if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1, - green_inverse) == 0) - return 1; - - if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0) - return 1; - if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0) - return 1; - if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale, - PNG_FP_1) == 0) - return 1; - - return 0; /*success*/ -} - -static int -png_XYZ_normalize(png_XYZ *XYZ) -{ - png_int_32 Y; - - if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 || - XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 || - XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0) - return 1; - - /* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1. - * IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore - * relying on addition of two positive values producing a negative one is not - * safe. - */ - Y = XYZ->red_Y; - if (0x7fffffff - Y < XYZ->green_X) - return 1; - Y += XYZ->green_Y; - if (0x7fffffff - Y < XYZ->blue_X) - return 1; - Y += XYZ->blue_Y; - - if (Y != PNG_FP_1) - { - if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0) - return 1; - if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0) - return 1; - if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0) - return 1; - - if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0) - return 1; - if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0) - return 1; - if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0) - return 1; - - if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0) - return 1; - if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0) - return 1; - if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0) - return 1; - } - - return 0; -} - -static int -png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta) -{ - /* Allow an error of +/-0.01 (absolute value) on each chromaticity */ - if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) || - PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) || - PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) || - PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) || - PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) || - PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) || - PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) || - PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta)) - return 0; - return 1; -} - -/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM - * chunk chromaticities. Earlier checks used to simply look for the overflow - * condition (where the determinant of the matrix to solve for XYZ ends up zero - * because the chromaticity values are not all distinct.) Despite this it is - * theoretically possible to produce chromaticities that are apparently valid - * but that rapidly degrade to invalid, potentially crashing, sets because of - * arithmetic inaccuracies when calculations are performed on them. The new - * check is to round-trip xy -> XYZ -> xy and then check that the result is - * within a small percentage of the original. - */ -static int -png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy) -{ - int result; - png_xy xy_test; - - /* As a side-effect this routine also returns the XYZ endpoints. */ - result = png_XYZ_from_xy(XYZ, xy); - if (result != 0) - return result; - - result = png_xy_from_XYZ(&xy_test, XYZ); - if (result != 0) - return result; - - if (png_colorspace_endpoints_match(xy, &xy_test, - 5/*actually, the math is pretty accurate*/) != 0) - return 0; - - /* Too much slip */ - return 1; -} - -/* This is the check going the other way. The XYZ is modified to normalize it - * (another side-effect) and the xy chromaticities are returned. - */ -static int -png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ) -{ - int result; - png_XYZ XYZtemp; - - result = png_XYZ_normalize(XYZ); - if (result != 0) - return result; - - result = png_xy_from_XYZ(xy, XYZ); - if (result != 0) - return result; - - XYZtemp = *XYZ; - return png_colorspace_check_xy(&XYZtemp, xy); -} - -/* Used to check for an endpoint match against sRGB */ -static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */ -{ - /* color x y */ - /* red */ 64000, 33000, - /* green */ 30000, 60000, - /* blue */ 15000, 6000, - /* white */ 31270, 32900 -}; - -static int -png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr, - png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ, - int preferred) -{ - if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0) - return 0; - - /* The consistency check is performed on the chromaticities; this factors out - * variations because of the normalization (or not) of the end point Y - * values. - */ - if (preferred < 2 && - (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0) - { - /* The end points must be reasonably close to any we already have. The - * following allows an error of up to +/-.001 - */ - if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy, - 100) == 0) - { - colorspace->flags |= PNG_COLORSPACE_INVALID; - png_benign_error(png_ptr, "inconsistent chromaticities"); - return 0; /* failed */ - } - - /* Only overwrite with preferred values */ - if (preferred == 0) - return 1; /* ok, but no change */ - } - - colorspace->end_points_xy = *xy; - colorspace->end_points_XYZ = *XYZ; - colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS; - - /* The end points are normally quoted to two decimal digits, so allow +/-0.01 - * on this test. - */ - if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0) - colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB; - - else - colorspace->flags &= PNG_COLORSPACE_CANCEL( - PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB); - - return 2; /* ok and changed */ -} - -int /* PRIVATE */ -png_colorspace_set_chromaticities(png_const_structrp png_ptr, - png_colorspacerp colorspace, const png_xy *xy, int preferred) -{ - /* We must check the end points to ensure they are reasonable - in the past - * color management systems have crashed as a result of getting bogus - * colorant values, while this isn't the fault of libpng it is the - * responsibility of libpng because PNG carries the bomb and libpng is in a - * position to protect against it. - */ - png_XYZ XYZ; - - switch (png_colorspace_check_xy(&XYZ, xy)) - { - case 0: /* success */ - return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ, - preferred); - - case 1: - /* We can't invert the chromaticities so we can't produce value XYZ - * values. Likely as not a color management system will fail too. - */ - colorspace->flags |= PNG_COLORSPACE_INVALID; - png_benign_error(png_ptr, "invalid chromaticities"); - break; - - default: - /* libpng is broken; this should be a warning but if it happens we - * want error reports so for the moment it is an error. - */ - colorspace->flags |= PNG_COLORSPACE_INVALID; - png_error(png_ptr, "internal error checking chromaticities"); - } - - return 0; /* failed */ -} - -int /* PRIVATE */ -png_colorspace_set_endpoints(png_const_structrp png_ptr, - png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred) -{ - png_XYZ XYZ = *XYZ_in; - png_xy xy; - - switch (png_colorspace_check_XYZ(&xy, &XYZ)) - { - case 0: - return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ, - preferred); - - case 1: - /* End points are invalid. */ - colorspace->flags |= PNG_COLORSPACE_INVALID; - png_benign_error(png_ptr, "invalid end points"); - break; - - default: - colorspace->flags |= PNG_COLORSPACE_INVALID; - png_error(png_ptr, "internal error checking chromaticities"); - } - - return 0; /* failed */ -} - -#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED) -/* Error message generation */ -static char -png_icc_tag_char(png_uint_32 byte) -{ - byte &= 0xff; - if (byte >= 32 && byte <= 126) - return (char)byte; - else - return '?'; -} - -static void -png_icc_tag_name(char *name, png_uint_32 tag) -{ - name[0] = '\''; - name[1] = png_icc_tag_char(tag >> 24); - name[2] = png_icc_tag_char(tag >> 16); - name[3] = png_icc_tag_char(tag >> 8); - name[4] = png_icc_tag_char(tag ); - name[5] = '\''; -} - -static int -is_ICC_signature_char(png_alloc_size_t it) -{ - return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) || - (it >= 97 && it <= 122); -} - -static int -is_ICC_signature(png_alloc_size_t it) -{ - return is_ICC_signature_char(it >> 24) /* checks all the top bits */ && - is_ICC_signature_char((it >> 16) & 0xff) && - is_ICC_signature_char((it >> 8) & 0xff) && - is_ICC_signature_char(it & 0xff); -} - -static int -png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace, - png_const_charp name, png_alloc_size_t value, png_const_charp reason) -{ - size_t pos; - char message[196]; /* see below for calculation */ - - if (colorspace != NULL) - colorspace->flags |= PNG_COLORSPACE_INVALID; - - pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */ - pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */ - pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */ - if (is_ICC_signature(value) != 0) - { - /* So 'value' is at most 4 bytes and the following cast is safe */ - png_icc_tag_name(message+pos, (png_uint_32)value); - pos += 6; /* total +8; less than the else clause */ - message[pos++] = ':'; - message[pos++] = ' '; - } -# ifdef PNG_WARNINGS_SUPPORTED - else - { - char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/ - - pos = png_safecat(message, (sizeof message), pos, - png_format_number(number, number+(sizeof number), - PNG_NUMBER_FORMAT_x, value)); - pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/ - } -# endif - /* The 'reason' is an arbitrary message, allow +79 maximum 195 */ - pos = png_safecat(message, (sizeof message), pos, reason); - PNG_UNUSED(pos) - - /* This is recoverable, but make it unconditionally an app_error on write to - * avoid writing invalid ICC profiles into PNG files (i.e., we handle them - * on read, with a warning, but on write unless the app turns off - * application errors the PNG won't be written.) - */ - png_chunk_report(png_ptr, message, - (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR); - - return 0; -} -#endif /* sRGB || iCCP */ - -#ifdef PNG_sRGB_SUPPORTED -int /* PRIVATE */ -png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace, - int intent) -{ - /* sRGB sets known gamma, end points and (from the chunk) intent. */ - /* IMPORTANT: these are not necessarily the values found in an ICC profile - * because ICC profiles store values adapted to a D50 environment; it is - * expected that the ICC profile mediaWhitePointTag will be D50; see the - * checks and code elsewhere to understand this better. - * - * These XYZ values, which are accurate to 5dp, produce rgb to gray - * coefficients of (6968,23435,2366), which are reduced (because they add up - * to 32769 not 32768) to (6968,23434,2366). These are the values that - * libpng has traditionally used (and are the best values given the 15bit - * algorithm used by the rgb to gray code.) - */ - static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */ - { - /* color X Y Z */ - /* red */ 41239, 21264, 1933, - /* green */ 35758, 71517, 11919, - /* blue */ 18048, 7219, 95053 - }; - - /* Do nothing if the colorspace is already invalidated. */ - if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0) - return 0; - - /* Check the intent, then check for existing settings. It is valid for the - * PNG file to have cHRM or gAMA chunks along with sRGB, but the values must - * be consistent with the correct values. If, however, this function is - * called below because an iCCP chunk matches sRGB then it is quite - * conceivable that an older app recorded incorrect gAMA and cHRM because of - * an incorrect calculation based on the values in the profile - this does - * *not* invalidate the profile (though it still produces an error, which can - * be ignored.) - */ - if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST) - return png_icc_profile_error(png_ptr, colorspace, "sRGB", - (unsigned)intent, "invalid sRGB rendering intent"); - - if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 && - colorspace->rendering_intent != intent) - return png_icc_profile_error(png_ptr, colorspace, "sRGB", - (unsigned)intent, "inconsistent rendering intents"); - - if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0) - { - png_benign_error(png_ptr, "duplicate sRGB information ignored"); - return 0; - } - - /* If the standard sRGB cHRM chunk does not match the one from the PNG file - * warn but overwrite the value with the correct one. - */ - if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 && - !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy, - 100)) - png_chunk_report(png_ptr, "cHRM chunk does not match sRGB", - PNG_CHUNK_ERROR); - - /* This check is just done for the error reporting - the routine always - * returns true when the 'from' argument corresponds to sRGB (2). - */ - (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE, - 2/*from sRGB*/); - - /* intent: bugs in GCC force 'int' to be used as the parameter type. */ - colorspace->rendering_intent = (png_uint_16)intent; - colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT; - - /* endpoints */ - colorspace->end_points_xy = sRGB_xy; - colorspace->end_points_XYZ = sRGB_XYZ; - colorspace->flags |= - (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB); - - /* gamma */ - colorspace->gamma = PNG_GAMMA_sRGB_INVERSE; - colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA; - - /* Finally record that we have an sRGB profile */ - colorspace->flags |= - (PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB); - - return 1; /* set */ -} -#endif /* sRGB */ - -#ifdef PNG_iCCP_SUPPORTED -/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value - * is XYZ(0.9642,1.0,0.8249), which scales to: - * - * (63189.8112, 65536, 54060.6464) - */ -static const png_byte D50_nCIEXYZ[12] = - { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d }; - -int /* PRIVATE */ -png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace, - png_const_charp name, png_uint_32 profile_length) -{ - if (profile_length < 132) - return png_icc_profile_error(png_ptr, colorspace, name, profile_length, - "too short"); - - return 1; -} - -int /* PRIVATE */ -png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace, - png_const_charp name, png_uint_32 profile_length, - png_const_bytep profile/* first 132 bytes only */, int color_type) -{ - png_uint_32 temp; - - /* Length check; this cannot be ignored in this code because profile_length - * is used later to check the tag table, so even if the profile seems over - * long profile_length from the caller must be correct. The caller can fix - * this up on read or write by just passing in the profile header length. - */ - temp = png_get_uint_32(profile); - if (temp != profile_length) - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "length does not match profile"); - - temp = (png_uint_32) (*(profile+8)); - if (temp > 3 && (profile_length & 3)) - return png_icc_profile_error(png_ptr, colorspace, name, profile_length, - "invalid length"); - - temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */ - if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */ - profile_length < 132+12*temp) /* truncated tag table */ - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "tag count too large"); - - /* The 'intent' must be valid or we can't store it, ICC limits the intent to - * 16 bits. - */ - temp = png_get_uint_32(profile+64); - if (temp >= 0xffff) /* The ICC limit */ - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "invalid rendering intent"); - - /* This is just a warning because the profile may be valid in future - * versions. - */ - if (temp >= PNG_sRGB_INTENT_LAST) - (void)png_icc_profile_error(png_ptr, NULL, name, temp, - "intent outside defined range"); - - /* At this point the tag table can't be checked because it hasn't necessarily - * been loaded; however, various header fields can be checked. These checks - * are for values permitted by the PNG spec in an ICC profile; the PNG spec - * restricts the profiles that can be passed in an iCCP chunk (they must be - * appropriate to processing PNG data!) - */ - - /* Data checks (could be skipped). These checks must be independent of the - * version number; however, the version number doesn't accomodate changes in - * the header fields (just the known tags and the interpretation of the - * data.) - */ - temp = png_get_uint_32(profile+36); /* signature 'ascp' */ - if (temp != 0x61637370) - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "invalid signature"); - - /* Currently the PCS illuminant/adopted white point (the computational - * white point) are required to be D50, - * however the profile contains a record of the illuminant so perhaps ICC - * expects to be able to change this in the future (despite the rationale in - * the introduction for using a fixed PCS adopted white.) Consequently the - * following is just a warning. - */ - if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0) - (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/, - "PCS illuminant is not D50"); - - /* The PNG spec requires this: - * "If the iCCP chunk is present, the image samples conform to the colour - * space represented by the embedded ICC profile as defined by the - * International Color Consortium [ICC]. The colour space of the ICC profile - * shall be an RGB colour space for colour images (PNG colour types 2, 3, and - * 6), or a greyscale colour space for greyscale images (PNG colour types 0 - * and 4)." - * - * This checking code ensures the embedded profile (on either read or write) - * conforms to the specification requirements. Notice that an ICC 'gray' - * color-space profile contains the information to transform the monochrome - * data to XYZ or L*a*b (according to which PCS the profile uses) and this - * should be used in preference to the standard libpng K channel replication - * into R, G and B channels. - * - * Previously it was suggested that an RGB profile on grayscale data could be - * handled. However it it is clear that using an RGB profile in this context - * must be an error - there is no specification of what it means. Thus it is - * almost certainly more correct to ignore the profile. - */ - temp = png_get_uint_32(profile+16); /* data colour space field */ - switch (temp) - { - case 0x52474220: /* 'RGB ' */ - if ((color_type & PNG_COLOR_MASK_COLOR) == 0) - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "RGB color space not permitted on grayscale PNG"); - break; - - case 0x47524159: /* 'GRAY' */ - if ((color_type & PNG_COLOR_MASK_COLOR) != 0) - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "Gray color space not permitted on RGB PNG"); - break; - - default: - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "invalid ICC profile color space"); - } - - /* It is up to the application to check that the profile class matches the - * application requirements; the spec provides no guidance, but it's pretty - * weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer - * ('prtr') or 'spac' (for generic color spaces). Issue a warning in these - * cases. Issue an error for device link or abstract profiles - these don't - * contain the records necessary to transform the color-space to anything - * other than the target device (and not even that for an abstract profile). - * Profiles of these classes may not be embedded in images. - */ - temp = png_get_uint_32(profile+12); /* profile/device class */ - switch (temp) - { - case 0x73636e72: /* 'scnr' */ - case 0x6d6e7472: /* 'mntr' */ - case 0x70727472: /* 'prtr' */ - case 0x73706163: /* 'spac' */ - /* All supported */ - break; - - case 0x61627374: /* 'abst' */ - /* May not be embedded in an image */ - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "invalid embedded Abstract ICC profile"); - - case 0x6c696e6b: /* 'link' */ - /* DeviceLink profiles cannot be interpreted in a non-device specific - * fashion, if an app uses the AToB0Tag in the profile the results are - * undefined unless the result is sent to the intended device, - * therefore a DeviceLink profile should not be found embedded in a - * PNG. - */ - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "unexpected DeviceLink ICC profile class"); - - case 0x6e6d636c: /* 'nmcl' */ - /* A NamedColor profile is also device specific, however it doesn't - * contain an AToB0 tag that is open to misinterpretation. Almost - * certainly it will fail the tests below. - */ - (void)png_icc_profile_error(png_ptr, NULL, name, temp, - "unexpected NamedColor ICC profile class"); - break; - - default: - /* To allow for future enhancements to the profile accept unrecognized - * profile classes with a warning, these then hit the test below on the - * tag content to ensure they are backward compatible with one of the - * understood profiles. - */ - (void)png_icc_profile_error(png_ptr, NULL, name, temp, - "unrecognized ICC profile class"); - break; - } - - /* For any profile other than a device link one the PCS must be encoded - * either in XYZ or Lab. - */ - temp = png_get_uint_32(profile+20); - switch (temp) - { - case 0x58595a20: /* 'XYZ ' */ - case 0x4c616220: /* 'Lab ' */ - break; - - default: - return png_icc_profile_error(png_ptr, colorspace, name, temp, - "unexpected ICC PCS encoding"); - } - - return 1; -} - -int /* PRIVATE */ -png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace, - png_const_charp name, png_uint_32 profile_length, - png_const_bytep profile /* header plus whole tag table */) -{ - png_uint_32 tag_count = png_get_uint_32(profile+128); - png_uint_32 itag; - png_const_bytep tag = profile+132; /* The first tag */ - - /* First scan all the tags in the table and add bits to the icc_info value - * (temporarily in 'tags'). - */ - for (itag=0; itag < tag_count; ++itag, tag += 12) - { - png_uint_32 tag_id = png_get_uint_32(tag+0); - png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */ - png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */ - - /* The ICC specification does not exclude zero length tags, therefore the - * start might actually be anywhere if there is no data, but this would be - * a clear abuse of the intent of the standard so the start is checked for - * being in range. All defined tag types have an 8 byte header - a 4 byte - * type signature then 0. - */ - if ((tag_start & 3) != 0) - { - /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is - * only a warning here because libpng does not care about the - * alignment. - */ - (void)png_icc_profile_error(png_ptr, NULL, name, tag_id, - "ICC profile tag start not a multiple of 4"); - } - - /* This is a hard error; potentially it can cause read outside the - * profile. - */ - if (tag_start > profile_length || tag_length > profile_length - tag_start) - return png_icc_profile_error(png_ptr, colorspace, name, tag_id, - "ICC profile tag outside profile"); - } - - return 1; /* success, maybe with warnings */ -} - -#ifdef PNG_sRGB_SUPPORTED -#if PNG_sRGB_PROFILE_CHECKS >= 0 -/* Information about the known ICC sRGB profiles */ -static const struct -{ - png_uint_32 adler, crc, length; - png_uint_32 md5[4]; - png_byte have_md5; - png_byte is_broken; - png_uint_16 intent; - -# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0) -# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\ - { adler, crc, length, md5, broke, intent }, - -} png_sRGB_checks[] = -{ - /* This data comes from contrib/tools/checksum-icc run on downloads of - * all four ICC sRGB profiles from www.color.org. - */ - /* adler32, crc32, MD5[4], intent, date, length, file-name */ - PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9, - PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0, - "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc") - - /* ICC sRGB v2 perceptual no black-compensation: */ - PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21, - PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0, - "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc") - - PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae, - PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0, - "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc") - - /* ICC sRGB v4 perceptual */ - PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812, - PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0, - "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc") - - /* The following profiles have no known MD5 checksum. If there is a match - * on the (empty) MD5 the other fields are used to attempt a match and - * a warning is produced. The first two of these profiles have a 'cprt' tag - * which suggests that they were also made by Hewlett Packard. - */ - PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce, - PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0, - "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc") - - /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not - * match the D50 PCS illuminant in the header (it is in fact the D65 values, - * so the white point is recorded as the un-adapted value.) The profiles - * below only differ in one byte - the intent - and are basically the same as - * the previous profile except for the mediaWhitePointTag error and a missing - * chromaticAdaptationTag. - */ - PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552, - PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/, - "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual") - - PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d, - PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/, - "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative") -}; - -static int -png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr, - png_const_bytep profile, uLong adler) -{ - /* The quick check is to verify just the MD5 signature and trust the - * rest of the data. Because the profile has already been verified for - * correctness this is safe. png_colorspace_set_sRGB will check the 'intent' - * field too, so if the profile has been edited with an intent not defined - * by sRGB (but maybe defined by a later ICC specification) the read of - * the profile will fail at that point. - */ - - png_uint_32 length = 0; - png_uint_32 intent = 0x10000; /* invalid */ -#if PNG_sRGB_PROFILE_CHECKS > 1 - uLong crc = 0; /* the value for 0 length data */ -#endif - unsigned int i; - -#ifdef PNG_SET_OPTION_SUPPORTED - /* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */ - if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) == - PNG_OPTION_ON) - return 0; -#endif - - for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i) - { - if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] && - png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] && - png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] && - png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3]) - { - /* This may be one of the old HP profiles without an MD5, in that - * case we can only use the length and Adler32 (note that these - * are not used by default if there is an MD5!) - */ -# if PNG_sRGB_PROFILE_CHECKS == 0 - if (png_sRGB_checks[i].have_md5 != 0) - return 1+png_sRGB_checks[i].is_broken; -# endif - - /* Profile is unsigned or more checks have been configured in. */ - if (length == 0) - { - length = png_get_uint_32(profile); - intent = png_get_uint_32(profile+64); - } - - /* Length *and* intent must match */ - if (length == (png_uint_32) png_sRGB_checks[i].length && - intent == (png_uint_32) png_sRGB_checks[i].intent) - { - /* Now calculate the adler32 if not done already. */ - if (adler == 0) - { - adler = adler32(0, NULL, 0); - adler = adler32(adler, profile, length); - } - - if (adler == png_sRGB_checks[i].adler) - { - /* These basic checks suggest that the data has not been - * modified, but if the check level is more than 1 perform - * our own crc32 checksum on the data. - */ -# if PNG_sRGB_PROFILE_CHECKS > 1 - if (crc == 0) - { - crc = crc32(0, NULL, 0); - crc = crc32(crc, profile, length); - } - - /* So this check must pass for the 'return' below to happen. - */ - if (crc == png_sRGB_checks[i].crc) -# endif - { - if (png_sRGB_checks[i].is_broken != 0) - { - /* These profiles are known to have bad data that may cause - * problems if they are used, therefore attempt to - * discourage their use, skip the 'have_md5' warning below, - * which is made irrelevant by this error. - */ - png_chunk_report(png_ptr, "known incorrect sRGB profile", - PNG_CHUNK_ERROR); - } - - /* Warn that this being done; this isn't even an error since - * the profile is perfectly valid, but it would be nice if - * people used the up-to-date ones. - */ - else if (png_sRGB_checks[i].have_md5 == 0) - { - png_chunk_report(png_ptr, - "out-of-date sRGB profile with no signature", - PNG_CHUNK_WARNING); - } - - return 1+png_sRGB_checks[i].is_broken; - } - } - -# if PNG_sRGB_PROFILE_CHECKS > 0 - /* The signature matched, but the profile had been changed in some - * way. This probably indicates a data error or uninformed hacking. - * Fall through to "no match". - */ - png_chunk_report(png_ptr, - "Not recognizing known sRGB profile that has been edited", - PNG_CHUNK_WARNING); - break; -# endif - } - } - } - - return 0; /* no match */ -} -#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */ - -void /* PRIVATE */ -png_icc_set_sRGB(png_const_structrp png_ptr, - png_colorspacerp colorspace, png_const_bytep profile, uLong adler) -{ - /* Is this profile one of the known ICC sRGB profiles? If it is, just set - * the sRGB information. - */ -#if PNG_sRGB_PROFILE_CHECKS >= 0 - if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0) -#endif - (void)png_colorspace_set_sRGB(png_ptr, colorspace, - (int)/*already checked*/png_get_uint_32(profile+64)); -} -#endif /* sRGB */ - -int /* PRIVATE */ -png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace, - png_const_charp name, png_uint_32 profile_length, png_const_bytep profile, - int color_type) -{ - if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0) - return 0; - - if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 && - png_icc_check_header(png_ptr, colorspace, name, profile_length, profile, - color_type) != 0 && - png_icc_check_tag_table(png_ptr, colorspace, name, profile_length, - profile) != 0) - { -# ifdef PNG_sRGB_SUPPORTED - /* If no sRGB support, don't try storing sRGB information */ - png_icc_set_sRGB(png_ptr, colorspace, profile, 0); -# endif - return 1; - } - - /* Failure case */ - return 0; -} -#endif /* iCCP */ - -#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED -void /* PRIVATE */ -png_colorspace_set_rgb_coefficients(png_structrp png_ptr) -{ - /* Set the rgb_to_gray coefficients from the colorspace. */ - if (png_ptr->rgb_to_gray_coefficients_set == 0 && - (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0) - { - /* png_set_background has not been called, get the coefficients from the Y - * values of the colorspace colorants. - */ - png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y; - png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y; - png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y; - png_fixed_point total = r+g+b; - - if (total > 0 && - r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 && - g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 && - b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 && - r+g+b <= 32769) - { - /* We allow 0 coefficients here. r+g+b may be 32769 if two or - * all of the coefficients were rounded up. Handle this by - * reducing the *largest* coefficient by 1; this matches the - * approach used for the default coefficients in pngrtran.c - */ - int add = 0; - - if (r+g+b > 32768) - add = -1; - else if (r+g+b < 32768) - add = 1; - - if (add != 0) - { - if (g >= r && g >= b) - g += add; - else if (r >= g && r >= b) - r += add; - else - b += add; - } - - /* Check for an internal error. */ - if (r+g+b != 32768) - png_error(png_ptr, - "internal error handling cHRM coefficients"); - - else - { - png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r; - png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g; - } - } - - /* This is a png_error at present even though it could be ignored - - * it should never happen, but it is important that if it does, the - * bug is fixed. - */ - else - png_error(png_ptr, "internal error handling cHRM->XYZ"); - } -} -#endif /* READ_RGB_TO_GRAY */ - -#endif /* COLORSPACE */ - -#ifdef __GNUC__ -/* This exists solely to work round a warning from GNU C. */ -static int /* PRIVATE */ -png_gt(size_t a, size_t b) -{ - return a > b; -} -#else -# define png_gt(a,b) ((a) > (b)) -#endif - -void /* PRIVATE */ -png_check_IHDR(png_const_structrp png_ptr, - png_uint_32 width, png_uint_32 height, int bit_depth, - int color_type, int interlace_type, int compression_type, - int filter_type) -{ - int error = 0; - - /* Check for width and height valid values */ - if (width == 0) - { - png_warning(png_ptr, "Image width is zero in IHDR"); - error = 1; - } - - if (width > PNG_UINT_31_MAX) - { - png_warning(png_ptr, "Invalid image width in IHDR"); - error = 1; - } - - if (png_gt(((width + 7) & (~7)), - ((PNG_SIZE_MAX - - 48 /* big_row_buf hack */ - - 1) /* filter byte */ - / 8) /* 8-byte RGBA pixels */ - - 1)) /* extra max_pixel_depth pad */ - { - /* The size of the row must be within the limits of this architecture. - * Because the read code can perform arbitrary transformations the - * maximum size is checked here. Because the code in png_read_start_row - * adds extra space "for safety's sake" in several places a conservative - * limit is used here. - * - * NOTE: it would be far better to check the size that is actually used, - * but the effect in the real world is minor and the changes are more - * extensive, therefore much more dangerous and much more difficult to - * write in a way that avoids compiler warnings. - */ - png_warning(png_ptr, "Image width is too large for this architecture"); - error = 1; - } - -#ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (width > png_ptr->user_width_max) -#else - if (width > PNG_USER_WIDTH_MAX) -#endif - { - png_warning(png_ptr, "Image width exceeds user limit in IHDR"); - error = 1; - } - - if (height == 0) - { - png_warning(png_ptr, "Image height is zero in IHDR"); - error = 1; - } - - if (height > PNG_UINT_31_MAX) - { - png_warning(png_ptr, "Invalid image height in IHDR"); - error = 1; - } - -#ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (height > png_ptr->user_height_max) -#else - if (height > PNG_USER_HEIGHT_MAX) -#endif - { - png_warning(png_ptr, "Image height exceeds user limit in IHDR"); - error = 1; - } - - /* Check other values */ - if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 && - bit_depth != 8 && bit_depth != 16) - { - png_warning(png_ptr, "Invalid bit depth in IHDR"); - error = 1; - } - - if (color_type < 0 || color_type == 1 || - color_type == 5 || color_type > 6) - { - png_warning(png_ptr, "Invalid color type in IHDR"); - error = 1; - } - - if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) || - ((color_type == PNG_COLOR_TYPE_RGB || - color_type == PNG_COLOR_TYPE_GRAY_ALPHA || - color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8)) - { - png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR"); - error = 1; - } - - if (interlace_type >= PNG_INTERLACE_LAST) - { - png_warning(png_ptr, "Unknown interlace method in IHDR"); - error = 1; - } - - if (compression_type != PNG_COMPRESSION_TYPE_BASE) - { - png_warning(png_ptr, "Unknown compression method in IHDR"); - error = 1; - } - -#ifdef PNG_MNG_FEATURES_SUPPORTED - /* Accept filter_method 64 (intrapixel differencing) only if - * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and - * 2. Libpng did not read a PNG signature (this filter_method is only - * used in PNG datastreams that are embedded in MNG datastreams) and - * 3. The application called png_permit_mng_features with a mask that - * included PNG_FLAG_MNG_FILTER_64 and - * 4. The filter_method is 64 and - * 5. The color_type is RGB or RGBA - */ - if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 && - png_ptr->mng_features_permitted != 0) - png_warning(png_ptr, "MNG features are not allowed in a PNG datastream"); - - if (filter_type != PNG_FILTER_TYPE_BASE) - { - if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && - (filter_type == PNG_INTRAPIXEL_DIFFERENCING) && - ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && - (color_type == PNG_COLOR_TYPE_RGB || - color_type == PNG_COLOR_TYPE_RGB_ALPHA))) - { - png_warning(png_ptr, "Unknown filter method in IHDR"); - error = 1; - } - - if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0) - { - png_warning(png_ptr, "Invalid filter method in IHDR"); - error = 1; - } - } - -#else - if (filter_type != PNG_FILTER_TYPE_BASE) - { - png_warning(png_ptr, "Unknown filter method in IHDR"); - error = 1; - } -#endif - - if (error == 1) - png_error(png_ptr, "Invalid IHDR data"); -} - -#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED) -/* ASCII to fp functions */ -/* Check an ASCII formated floating point value, see the more detailed - * comments in pngpriv.h - */ -/* The following is used internally to preserve the sticky flags */ -#define png_fp_add(state, flags) ((state) |= (flags)) -#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY)) - -int /* PRIVATE */ -png_check_fp_number(png_const_charp string, png_size_t size, int *statep, - png_size_tp whereami) -{ - int state = *statep; - png_size_t i = *whereami; - - while (i < size) - { - int type; - /* First find the type of the next character */ - switch (string[i]) - { - case 43: type = PNG_FP_SAW_SIGN; break; - case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break; - case 46: type = PNG_FP_SAW_DOT; break; - case 48: type = PNG_FP_SAW_DIGIT; break; - case 49: case 50: case 51: case 52: - case 53: case 54: case 55: case 56: - case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break; - case 69: - case 101: type = PNG_FP_SAW_E; break; - default: goto PNG_FP_End; - } - - /* Now deal with this type according to the current - * state, the type is arranged to not overlap the - * bits of the PNG_FP_STATE. - */ - switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY)) - { - case PNG_FP_INTEGER + PNG_FP_SAW_SIGN: - if ((state & PNG_FP_SAW_ANY) != 0) - goto PNG_FP_End; /* not a part of the number */ - - png_fp_add(state, type); - break; - - case PNG_FP_INTEGER + PNG_FP_SAW_DOT: - /* Ok as trailer, ok as lead of fraction. */ - if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */ - goto PNG_FP_End; - - else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */ - png_fp_add(state, type); - - else - png_fp_set(state, PNG_FP_FRACTION | type); - - break; - - case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT: - if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */ - png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT); - - png_fp_add(state, type | PNG_FP_WAS_VALID); - - break; - - case PNG_FP_INTEGER + PNG_FP_SAW_E: - if ((state & PNG_FP_SAW_DIGIT) == 0) - goto PNG_FP_End; - - png_fp_set(state, PNG_FP_EXPONENT); - - break; - - /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN: - goto PNG_FP_End; ** no sign in fraction */ - - /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT: - goto PNG_FP_End; ** Because SAW_DOT is always set */ - - case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT: - png_fp_add(state, type | PNG_FP_WAS_VALID); - break; - - case PNG_FP_FRACTION + PNG_FP_SAW_E: - /* This is correct because the trailing '.' on an - * integer is handled above - so we can only get here - * with the sequence ".E" (with no preceding digits). - */ - if ((state & PNG_FP_SAW_DIGIT) == 0) - goto PNG_FP_End; - - png_fp_set(state, PNG_FP_EXPONENT); - - break; - - case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN: - if ((state & PNG_FP_SAW_ANY) != 0) - goto PNG_FP_End; /* not a part of the number */ - - png_fp_add(state, PNG_FP_SAW_SIGN); - - break; - - /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT: - goto PNG_FP_End; */ - - case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT: - png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID); - - break; - - /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E: - goto PNG_FP_End; */ - - default: goto PNG_FP_End; /* I.e. break 2 */ - } - - /* The character seems ok, continue. */ - ++i; - } - -PNG_FP_End: - /* Here at the end, update the state and return the correct - * return code. - */ - *statep = state; - *whereami = i; - - return (state & PNG_FP_SAW_DIGIT) != 0; -} - - -/* The same but for a complete string. */ -int -png_check_fp_string(png_const_charp string, png_size_t size) -{ - int state=0; - png_size_t char_index=0; - - if (png_check_fp_number(string, size, &state, &char_index) != 0 && - (char_index == size || string[char_index] == 0)) - return state /* must be non-zero - see above */; - - return 0; /* i.e. fail */ -} -#endif /* pCAL || sCAL */ - -#ifdef PNG_sCAL_SUPPORTED -# ifdef PNG_FLOATING_POINT_SUPPORTED -/* Utility used below - a simple accurate power of ten from an integral - * exponent. - */ -static double -png_pow10(int power) -{ - int recip = 0; - double d = 1; - - /* Handle negative exponent with a reciprocal at the end because - * 10 is exact whereas .1 is inexact in base 2 - */ - if (power < 0) - { - if (power < DBL_MIN_10_EXP) return 0; - recip = 1, power = -power; - } - - if (power > 0) - { - /* Decompose power bitwise. */ - double mult = 10; - do - { - if (power & 1) d *= mult; - mult *= mult; - power >>= 1; - } - while (power > 0); - - if (recip != 0) d = 1/d; - } - /* else power is 0 and d is 1 */ - - return d; -} - -/* Function to format a floating point value in ASCII with a given - * precision. - */ -void /* PRIVATE */ -png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size, - double fp, unsigned int precision) -{ - /* We use standard functions from math.h, but not printf because - * that would require stdio. The caller must supply a buffer of - * sufficient size or we will png_error. The tests on size and - * the space in ascii[] consumed are indicated below. - */ - if (precision < 1) - precision = DBL_DIG; - - /* Enforce the limit of the implementation precision too. */ - if (precision > DBL_DIG+1) - precision = DBL_DIG+1; - - /* Basic sanity checks */ - if (size >= precision+5) /* See the requirements below. */ - { - if (fp < 0) - { - fp = -fp; - *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */ - --size; - } - - if (fp >= DBL_MIN && fp <= DBL_MAX) - { - int exp_b10; /* A base 10 exponent */ - double base; /* 10^exp_b10 */ - - /* First extract a base 10 exponent of the number, - * the calculation below rounds down when converting - * from base 2 to base 10 (multiply by log10(2) - - * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to - * be increased. Note that the arithmetic shift - * performs a floor() unlike C arithmetic - using a - * C multiply would break the following for negative - * exponents. - */ - (void)frexp(fp, &exp_b10); /* exponent to base 2 */ - - exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */ - - /* Avoid underflow here. */ - base = png_pow10(exp_b10); /* May underflow */ - - while (base < DBL_MIN || base < fp) - { - /* And this may overflow. */ - double test = png_pow10(exp_b10+1); - - if (test <= DBL_MAX) - ++exp_b10, base = test; - - else - break; - } - - /* Normalize fp and correct exp_b10, after this fp is in the - * range [.1,1) and exp_b10 is both the exponent and the digit - * *before* which the decimal point should be inserted - * (starting with 0 for the first digit). Note that this - * works even if 10^exp_b10 is out of range because of the - * test on DBL_MAX above. - */ - fp /= base; - while (fp >= 1) fp /= 10, ++exp_b10; - - /* Because of the code above fp may, at this point, be - * less than .1, this is ok because the code below can - * handle the leading zeros this generates, so no attempt - * is made to correct that here. - */ - - { - unsigned int czero, clead, cdigits; - char exponent[10]; - - /* Allow up to two leading zeros - this will not lengthen - * the number compared to using E-n. - */ - if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */ - { - czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */ - exp_b10 = 0; /* Dot added below before first output. */ - } - else - czero = 0; /* No zeros to add */ - - /* Generate the digit list, stripping trailing zeros and - * inserting a '.' before a digit if the exponent is 0. - */ - clead = czero; /* Count of leading zeros */ - cdigits = 0; /* Count of digits in list. */ - - do - { - double d; - - fp *= 10; - /* Use modf here, not floor and subtract, so that - * the separation is done in one step. At the end - * of the loop don't break the number into parts so - * that the final digit is rounded. - */ - if (cdigits+czero+1 < precision+clead) - fp = modf(fp, &d); - - else - { - d = floor(fp + .5); - - if (d > 9) - { - /* Rounding up to 10, handle that here. */ - if (czero > 0) - { - --czero, d = 1; - if (cdigits == 0) --clead; - } - else - { - while (cdigits > 0 && d > 9) - { - int ch = *--ascii; - - if (exp_b10 != (-1)) - ++exp_b10; - - else if (ch == 46) - { - ch = *--ascii, ++size; - /* Advance exp_b10 to '1', so that the - * decimal point happens after the - * previous digit. - */ - exp_b10 = 1; - } - - --cdigits; - d = ch - 47; /* I.e. 1+(ch-48) */ - } - - /* Did we reach the beginning? If so adjust the - * exponent but take into account the leading - * decimal point. - */ - if (d > 9) /* cdigits == 0 */ - { - if (exp_b10 == (-1)) - { - /* Leading decimal point (plus zeros?), if - * we lose the decimal point here it must - * be reentered below. - */ - int ch = *--ascii; - - if (ch == 46) - ++size, exp_b10 = 1; - - /* Else lost a leading zero, so 'exp_b10' is - * still ok at (-1) - */ - } - else - ++exp_b10; - - /* In all cases we output a '1' */ - d = 1; - } - } - } - fp = 0; /* Guarantees termination below. */ - } - - if (d == 0) - { - ++czero; - if (cdigits == 0) ++clead; - } - else - { - /* Included embedded zeros in the digit count. */ - cdigits += czero - clead; - clead = 0; - - while (czero > 0) - { - /* exp_b10 == (-1) means we just output the decimal - * place - after the DP don't adjust 'exp_b10' any - * more! - */ - if (exp_b10 != (-1)) - { - if (exp_b10 == 0) *ascii++ = 46, --size; - /* PLUS 1: TOTAL 4 */ - --exp_b10; - } - *ascii++ = 48, --czero; - } - - if (exp_b10 != (-1)) - { - if (exp_b10 == 0) - *ascii++ = 46, --size; /* counted above */ - - --exp_b10; - } - *ascii++ = (char)(48 + (int)d), ++cdigits; - } - } - while (cdigits+czero < precision+clead && fp > DBL_MIN); - - /* The total output count (max) is now 4+precision */ - - /* Check for an exponent, if we don't need one we are - * done and just need to terminate the string. At - * this point exp_b10==(-1) is effectively if flag - it got - * to '-1' because of the decrement after outputting - * the decimal point above (the exponent required is - * *not* -1!) - */ - if (exp_b10 >= (-1) && exp_b10 <= 2) - { - /* The following only happens if we didn't output the - * leading zeros above for negative exponent, so this - * doesn't add to the digit requirement. Note that the - * two zeros here can only be output if the two leading - * zeros were *not* output, so this doesn't increase - * the output count. - */ - while (--exp_b10 >= 0) *ascii++ = 48; - - *ascii = 0; - - /* Total buffer requirement (including the '\0') is - * 5+precision - see check at the start. - */ - return; - } - - /* Here if an exponent is required, adjust size for - * the digits we output but did not count. The total - * digit output here so far is at most 1+precision - no - * decimal point and no leading or trailing zeros have - * been output. - */ - size -= cdigits; - - *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */ - - /* The following use of an unsigned temporary avoids ambiguities in - * the signed arithmetic on exp_b10 and permits GCC at least to do - * better optimization. - */ - { - unsigned int uexp_b10; - - if (exp_b10 < 0) - { - *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */ - uexp_b10 = -exp_b10; - } - - else - uexp_b10 = exp_b10; - - cdigits = 0; - - while (uexp_b10 > 0) - { - exponent[cdigits++] = (char)(48 + uexp_b10 % 10); - uexp_b10 /= 10; - } - } - - /* Need another size check here for the exponent digits, so - * this need not be considered above. - */ - if (size > cdigits) - { - while (cdigits > 0) *ascii++ = exponent[--cdigits]; - - *ascii = 0; - - return; - } - } - } - else if (!(fp >= DBL_MIN)) - { - *ascii++ = 48; /* '0' */ - *ascii = 0; - return; - } - else - { - *ascii++ = 105; /* 'i' */ - *ascii++ = 110; /* 'n' */ - *ascii++ = 102; /* 'f' */ - *ascii = 0; - return; - } - } - - /* Here on buffer too small. */ - png_error(png_ptr, "ASCII conversion buffer too small"); -} - -# endif /* FLOATING_POINT */ - -# ifdef PNG_FIXED_POINT_SUPPORTED -/* Function to format a fixed point value in ASCII. - */ -void /* PRIVATE */ -png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii, - png_size_t size, png_fixed_point fp) -{ - /* Require space for 10 decimal digits, a decimal point, a minus sign and a - * trailing \0, 13 characters: - */ - if (size > 12) - { - png_uint_32 num; - - /* Avoid overflow here on the minimum integer. */ - if (fp < 0) - *ascii++ = 45, num = -fp; - else - num = fp; - - if (num <= 0x80000000) /* else overflowed */ - { - unsigned int ndigits = 0, first = 16 /* flag value */; - char digits[10]; - - while (num) - { - /* Split the low digit off num: */ - unsigned int tmp = num/10; - num -= tmp*10; - digits[ndigits++] = (char)(48 + num); - /* Record the first non-zero digit, note that this is a number - * starting at 1, it's not actually the array index. - */ - if (first == 16 && num > 0) - first = ndigits; - num = tmp; - } - - if (ndigits > 0) - { - while (ndigits > 5) *ascii++ = digits[--ndigits]; - /* The remaining digits are fractional digits, ndigits is '5' or - * smaller at this point. It is certainly not zero. Check for a - * non-zero fractional digit: - */ - if (first <= 5) - { - unsigned int i; - *ascii++ = 46; /* decimal point */ - /* ndigits may be <5 for small numbers, output leading zeros - * then ndigits digits to first: - */ - i = 5; - while (ndigits < i) *ascii++ = 48, --i; - while (ndigits >= first) *ascii++ = digits[--ndigits]; - /* Don't output the trailing zeros! */ - } - } - else - *ascii++ = 48; - - /* And null terminate the string: */ - *ascii = 0; - return; - } - } - - /* Here on buffer too small. */ - png_error(png_ptr, "ASCII conversion buffer too small"); -} -# endif /* FIXED_POINT */ -#endif /* SCAL */ - -#if defined(PNG_FLOATING_POINT_SUPPORTED) && \ - !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \ - (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \ - defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \ - defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \ - (defined(PNG_sCAL_SUPPORTED) && \ - defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)) -png_fixed_point -png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text) -{ - double r = floor(100000 * fp + .5); - - if (r > 2147483647. || r < -2147483648.) - png_fixed_error(png_ptr, text); - -# ifndef PNG_ERROR_TEXT_SUPPORTED - PNG_UNUSED(text) -# endif - - return (png_fixed_point)r; -} -#endif - -#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\ - defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED) -/* muldiv functions */ -/* This API takes signed arguments and rounds the result to the nearest - * integer (or, for a fixed point number - the standard argument - to - * the nearest .00001). Overflow and divide by zero are signalled in - * the result, a boolean - true on success, false on overflow. - */ -int -png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times, - png_int_32 divisor) -{ - /* Return a * times / divisor, rounded. */ - if (divisor != 0) - { - if (a == 0 || times == 0) - { - *res = 0; - return 1; - } - else - { -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = a; - r *= times; - r /= divisor; - r = floor(r+.5); - - /* A png_fixed_point is a 32-bit integer. */ - if (r <= 2147483647. && r >= -2147483648.) - { - *res = (png_fixed_point)r; - return 1; - } -#else - int negative = 0; - png_uint_32 A, T, D; - png_uint_32 s16, s32, s00; - - if (a < 0) - negative = 1, A = -a; - else - A = a; - - if (times < 0) - negative = !negative, T = -times; - else - T = times; - - if (divisor < 0) - negative = !negative, D = -divisor; - else - D = divisor; - - /* Following can't overflow because the arguments only - * have 31 bits each, however the result may be 32 bits. - */ - s16 = (A >> 16) * (T & 0xffff) + - (A & 0xffff) * (T >> 16); - /* Can't overflow because the a*times bit is only 30 - * bits at most. - */ - s32 = (A >> 16) * (T >> 16) + (s16 >> 16); - s00 = (A & 0xffff) * (T & 0xffff); - - s16 = (s16 & 0xffff) << 16; - s00 += s16; - - if (s00 < s16) - ++s32; /* carry */ - - if (s32 < D) /* else overflow */ - { - /* s32.s00 is now the 64-bit product, do a standard - * division, we know that s32 < D, so the maximum - * required shift is 31. - */ - int bitshift = 32; - png_fixed_point result = 0; /* NOTE: signed */ - - while (--bitshift >= 0) - { - png_uint_32 d32, d00; - - if (bitshift > 0) - d32 = D >> (32-bitshift), d00 = D << bitshift; - - else - d32 = 0, d00 = D; - - if (s32 > d32) - { - if (s00 < d00) --s32; /* carry */ - s32 -= d32, s00 -= d00, result += 1<<bitshift; - } - - else - if (s32 == d32 && s00 >= d00) - s32 = 0, s00 -= d00, result += 1<<bitshift; - } - - /* Handle the rounding. */ - if (s00 >= (D >> 1)) - ++result; - - if (negative != 0) - result = -result; - - /* Check for overflow. */ - if ((negative != 0 && result <= 0) || - (negative == 0 && result >= 0)) - { - *res = result; - return 1; - } - } -#endif - } - } - - return 0; -} -#endif /* READ_GAMMA || INCH_CONVERSIONS */ - -#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED) -/* The following is for when the caller doesn't much care about the - * result. - */ -png_fixed_point -png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times, - png_int_32 divisor) -{ - png_fixed_point result; - - if (png_muldiv(&result, a, times, divisor) != 0) - return result; - - png_warning(png_ptr, "fixed point overflow ignored"); - return 0; -} -#endif - -#ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */ -/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */ -png_fixed_point -png_reciprocal(png_fixed_point a) -{ -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = floor(1E10/a+.5); - - if (r <= 2147483647. && r >= -2147483648.) - return (png_fixed_point)r; -#else - png_fixed_point res; - - if (png_muldiv(&res, 100000, 100000, a) != 0) - return res; -#endif - - return 0; /* error/overflow */ -} - -/* This is the shared test on whether a gamma value is 'significant' - whether - * it is worth doing gamma correction. - */ -int /* PRIVATE */ -png_gamma_significant(png_fixed_point gamma_val) -{ - return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED || - gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED; -} -#endif - -#ifdef PNG_READ_GAMMA_SUPPORTED -#ifdef PNG_16BIT_SUPPORTED -/* A local convenience routine. */ -static png_fixed_point -png_product2(png_fixed_point a, png_fixed_point b) -{ - /* The required result is 1/a * 1/b; the following preserves accuracy. */ -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = a * 1E-5; - r *= b; - r = floor(r+.5); - - if (r <= 2147483647. && r >= -2147483648.) - return (png_fixed_point)r; -#else - png_fixed_point res; - - if (png_muldiv(&res, a, b, 100000) != 0) - return res; -#endif - - return 0; /* overflow */ -} -#endif /* 16BIT */ - -/* The inverse of the above. */ -png_fixed_point -png_reciprocal2(png_fixed_point a, png_fixed_point b) -{ - /* The required result is 1/a * 1/b; the following preserves accuracy. */ -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - if (a != 0 && b != 0) - { - double r = 1E15/a; - r /= b; - r = floor(r+.5); - - if (r <= 2147483647. && r >= -2147483648.) - return (png_fixed_point)r; - } -#else - /* This may overflow because the range of png_fixed_point isn't symmetric, - * but this API is only used for the product of file and screen gamma so it - * doesn't matter that the smallest number it can produce is 1/21474, not - * 1/100000 - */ - png_fixed_point res = png_product2(a, b); - - if (res != 0) - return png_reciprocal(res); -#endif - - return 0; /* overflow */ -} -#endif /* READ_GAMMA */ - -#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */ -#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED -/* Fixed point gamma. - * - * The code to calculate the tables used below can be found in the shell script - * contrib/tools/intgamma.sh - * - * To calculate gamma this code implements fast log() and exp() calls using only - * fixed point arithmetic. This code has sufficient precision for either 8-bit - * or 16-bit sample values. - * - * The tables used here were calculated using simple 'bc' programs, but C double - * precision floating point arithmetic would work fine. - * - * 8-bit log table - * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to - * 255, so it's the base 2 logarithm of a normalized 8-bit floating point - * mantissa. The numbers are 32-bit fractions. - */ -static const png_uint_32 -png_8bit_l2[128] = -{ - 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U, - 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U, - 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U, - 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U, - 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U, - 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U, - 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U, - 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U, - 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U, - 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U, - 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U, - 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U, - 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U, - 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U, - 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U, - 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U, - 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U, - 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U, - 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U, - 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U, - 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U, - 24347096U, 0U - -#if 0 - /* The following are the values for 16-bit tables - these work fine for the - * 8-bit conversions but produce very slightly larger errors in the 16-bit - * log (about 1.2 as opposed to 0.7 absolute error in the final value). To - * use these all the shifts below must be adjusted appropriately. - */ - 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054, - 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803, - 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068, - 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782, - 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887, - 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339, - 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098, - 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132, - 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415, - 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523, - 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495, - 1119, 744, 372 -#endif -}; - -static png_int_32 -png_log8bit(unsigned int x) -{ - unsigned int lg2 = 0; - /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log, - * because the log is actually negate that means adding 1. The final - * returned value thus has the range 0 (for 255 input) to 7.994 (for 1 - * input), return -1 for the overflow (log 0) case, - so the result is - * always at most 19 bits. - */ - if ((x &= 0xff) == 0) - return -1; - - if ((x & 0xf0) == 0) - lg2 = 4, x <<= 4; - - if ((x & 0xc0) == 0) - lg2 += 2, x <<= 2; - - if ((x & 0x80) == 0) - lg2 += 1, x <<= 1; - - /* result is at most 19 bits, so this cast is safe: */ - return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16)); -} - -/* The above gives exact (to 16 binary places) log2 values for 8-bit images, - * for 16-bit images we use the most significant 8 bits of the 16-bit value to - * get an approximation then multiply the approximation by a correction factor - * determined by the remaining up to 8 bits. This requires an additional step - * in the 16-bit case. - * - * We want log2(value/65535), we have log2(v'/255), where: - * - * value = v' * 256 + v'' - * = v' * f - * - * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128 - * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less - * than 258. The final factor also needs to correct for the fact that our 8-bit - * value is scaled by 255, whereas the 16-bit values must be scaled by 65535. - * - * This gives a final formula using a calculated value 'x' which is value/v' and - * scaling by 65536 to match the above table: - * - * log2(x/257) * 65536 - * - * Since these numbers are so close to '1' we can use simple linear - * interpolation between the two end values 256/257 (result -368.61) and 258/257 - * (result 367.179). The values used below are scaled by a further 64 to give - * 16-bit precision in the interpolation: - * - * Start (256): -23591 - * Zero (257): 0 - * End (258): 23499 - */ -#ifdef PNG_16BIT_SUPPORTED -static png_int_32 -png_log16bit(png_uint_32 x) -{ - unsigned int lg2 = 0; - - /* As above, but now the input has 16 bits. */ - if ((x &= 0xffff) == 0) - return -1; - - if ((x & 0xff00) == 0) - lg2 = 8, x <<= 8; - - if ((x & 0xf000) == 0) - lg2 += 4, x <<= 4; - - if ((x & 0xc000) == 0) - lg2 += 2, x <<= 2; - - if ((x & 0x8000) == 0) - lg2 += 1, x <<= 1; - - /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional - * value. - */ - lg2 <<= 28; - lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4; - - /* Now we need to interpolate the factor, this requires a division by the top - * 8 bits. Do this with maximum precision. - */ - x = ((x << 16) + (x >> 9)) / (x >> 8); - - /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24, - * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly - * 16 bits to interpolate to get the low bits of the result. Round the - * answer. Note that the end point values are scaled by 64 to retain overall - * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust - * the overall scaling by 6-12. Round at every step. - */ - x -= 1U << 24; - - if (x <= 65536U) /* <= '257' */ - lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12); - - else - lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12); - - /* Safe, because the result can't have more than 20 bits: */ - return (png_int_32)((lg2 + 2048) >> 12); -} -#endif /* 16BIT */ - -/* The 'exp()' case must invert the above, taking a 20-bit fixed point - * logarithmic value and returning a 16 or 8-bit number as appropriate. In - * each case only the low 16 bits are relevant - the fraction - since the - * integer bits (the top 4) simply determine a shift. - * - * The worst case is the 16-bit distinction between 65535 and 65534. This - * requires perhaps spurious accuracy in the decoding of the logarithm to - * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance - * of getting this accuracy in practice. - * - * To deal with this the following exp() function works out the exponent of the - * frational part of the logarithm by using an accurate 32-bit value from the - * top four fractional bits then multiplying in the remaining bits. - */ -static const png_uint_32 -png_32bit_exp[16] = -{ - /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */ - 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U, - 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U, - 2553802834U, 2445529972U, 2341847524U, 2242560872U -}; - -/* Adjustment table; provided to explain the numbers in the code below. */ -#if 0 -for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"} - 11 44937.64284865548751208448 - 10 45180.98734845585101160448 - 9 45303.31936980687359311872 - 8 45364.65110595323018870784 - 7 45395.35850361789624614912 - 6 45410.72259715102037508096 - 5 45418.40724413220722311168 - 4 45422.25021786898173001728 - 3 45424.17186732298419044352 - 2 45425.13273269940811464704 - 1 45425.61317555035558641664 - 0 45425.85339951654943850496 -#endif - -static png_uint_32 -png_exp(png_fixed_point x) -{ - if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */ - { - /* Obtain a 4-bit approximation */ - png_uint_32 e = png_32bit_exp[(x >> 12) & 0x0f]; - - /* Incorporate the low 12 bits - these decrease the returned value by - * multiplying by a number less than 1 if the bit is set. The multiplier - * is determined by the above table and the shift. Notice that the values - * converge on 45426 and this is used to allow linear interpolation of the - * low bits. - */ - if (x & 0x800) - e -= (((e >> 16) * 44938U) + 16U) >> 5; - - if (x & 0x400) - e -= (((e >> 16) * 45181U) + 32U) >> 6; - - if (x & 0x200) - e -= (((e >> 16) * 45303U) + 64U) >> 7; - - if (x & 0x100) - e -= (((e >> 16) * 45365U) + 128U) >> 8; - - if (x & 0x080) - e -= (((e >> 16) * 45395U) + 256U) >> 9; - - if (x & 0x040) - e -= (((e >> 16) * 45410U) + 512U) >> 10; - - /* And handle the low 6 bits in a single block. */ - e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9; - - /* Handle the upper bits of x. */ - e >>= x >> 16; - return e; - } - - /* Check for overflow */ - if (x <= 0) - return png_32bit_exp[0]; - - /* Else underflow */ - return 0; -} - -static png_byte -png_exp8bit(png_fixed_point lg2) -{ - /* Get a 32-bit value: */ - png_uint_32 x = png_exp(lg2); - - /* Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the - * second, rounding, step can't overflow because of the first, subtraction, - * step. - */ - x -= x >> 8; - return (png_byte)(((x + 0x7fffffU) >> 24) & 0xff); -} - -#ifdef PNG_16BIT_SUPPORTED -static png_uint_16 -png_exp16bit(png_fixed_point lg2) -{ - /* Get a 32-bit value: */ - png_uint_32 x = png_exp(lg2); - - /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */ - x -= x >> 16; - return (png_uint_16)((x + 32767U) >> 16); -} -#endif /* 16BIT */ -#endif /* FLOATING_ARITHMETIC */ - -png_byte -png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val) -{ - if (value > 0 && value < 255) - { -# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - /* 'value' is unsigned, ANSI-C90 requires the compiler to correctly - * convert this to a floating point value. This includes values that - * would overflow if 'value' were to be converted to 'int'. - * - * Apparently GCC, however, does an intermediate conversion to (int) - * on some (ARM) but not all (x86) platforms, possibly because of - * hardware FP limitations. (E.g. if the hardware conversion always - * assumes the integer register contains a signed value.) This results - * in ANSI-C undefined behavior for large values. - * - * Other implementations on the same machine might actually be ANSI-C90 - * conformant and therefore compile spurious extra code for the large - * values. - * - * We can be reasonably sure that an unsigned to float conversion - * won't be faster than an int to float one. Therefore this code - * assumes responsibility for the undefined behavior, which it knows - * can't happen because of the check above. - * - * Note the argument to this routine is an (unsigned int) because, on - * 16-bit platforms, it is assigned a value which might be out of - * range for an (int); that would result in undefined behavior in the - * caller if the *argument* ('value') were to be declared (int). - */ - double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5); - return (png_byte)r; -# else - png_int_32 lg2 = png_log8bit(value); - png_fixed_point res; - - if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0) - return png_exp8bit(res); - - /* Overflow. */ - value = 0; -# endif - } - - return (png_byte)(value & 0xff); -} - -#ifdef PNG_16BIT_SUPPORTED -png_uint_16 -png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val) -{ - if (value > 0 && value < 65535) - { -# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - /* The same (unsigned int)->(double) constraints apply here as above, - * however in this case the (unsigned int) to (int) conversion can - * overflow on an ANSI-C90 compliant system so the cast needs to ensure - * that this is not possible. - */ - double r = floor(65535*pow((png_int_32)value/65535., - gamma_val*.00001)+.5); - return (png_uint_16)r; -# else - png_int_32 lg2 = png_log16bit(value); - png_fixed_point res; - - if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0) - return png_exp16bit(res); - - /* Overflow. */ - value = 0; -# endif - } - - return (png_uint_16)value; -} -#endif /* 16BIT */ - -/* This does the right thing based on the bit_depth field of the - * png_struct, interpreting values as 8-bit or 16-bit. While the result - * is nominally a 16-bit value if bit depth is 8 then the result is - * 8-bit (as are the arguments.) - */ -png_uint_16 /* PRIVATE */ -png_gamma_correct(png_structrp png_ptr, unsigned int value, - png_fixed_point gamma_val) -{ - if (png_ptr->bit_depth == 8) - return png_gamma_8bit_correct(value, gamma_val); - -#ifdef PNG_16BIT_SUPPORTED - else - return png_gamma_16bit_correct(value, gamma_val); -#else - /* should not reach this */ - return 0; -#endif /* 16BIT */ -} - -#ifdef PNG_16BIT_SUPPORTED -/* Internal function to build a single 16-bit table - the table consists of - * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount - * to shift the input values right (or 16-number_of_signifiant_bits). - * - * The caller is responsible for ensuring that the table gets cleaned up on - * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument - * should be somewhere that will be cleaned. - */ -static void -png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable, - PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) -{ - /* Various values derived from 'shift': */ - PNG_CONST unsigned int num = 1U << (8U - shift); -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - /* CSE the division and work round wacky GCC warnings (see the comments - * in png_gamma_8bit_correct for where these come from.) - */ - PNG_CONST double fmax = 1./(((png_int_32)1 << (16U - shift))-1); -#endif - PNG_CONST unsigned int max = (1U << (16U - shift))-1U; - PNG_CONST unsigned int max_by_2 = 1U << (15U-shift); - unsigned int i; - - png_uint_16pp table = *ptable = - (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p))); - - for (i = 0; i < num; i++) - { - png_uint_16p sub_table = table[i] = - (png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16))); - - /* The 'threshold' test is repeated here because it can arise for one of - * the 16-bit tables even if the others don't hit it. - */ - if (png_gamma_significant(gamma_val) != 0) - { - /* The old code would overflow at the end and this would cause the - * 'pow' function to return a result >1, resulting in an - * arithmetic error. This code follows the spec exactly; ig is - * the recovered input sample, it always has 8-16 bits. - * - * We want input * 65535/max, rounded, the arithmetic fits in 32 - * bits (unsigned) so long as max <= 32767. - */ - unsigned int j; - for (j = 0; j < 256; j++) - { - png_uint_32 ig = (j << (8-shift)) + i; -# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - /* Inline the 'max' scaling operation: */ - /* See png_gamma_8bit_correct for why the cast to (int) is - * required here. - */ - double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5); - sub_table[j] = (png_uint_16)d; -# else - if (shift != 0) - ig = (ig * 65535U + max_by_2)/max; - - sub_table[j] = png_gamma_16bit_correct(ig, gamma_val); -# endif - } - } - else - { - /* We must still build a table, but do it the fast way. */ - unsigned int j; - - for (j = 0; j < 256; j++) - { - png_uint_32 ig = (j << (8-shift)) + i; - - if (shift != 0) - ig = (ig * 65535U + max_by_2)/max; - - sub_table[j] = (png_uint_16)ig; - } - } - } -} - -/* NOTE: this function expects the *inverse* of the overall gamma transformation - * required. - */ -static void -png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable, - PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) -{ - PNG_CONST unsigned int num = 1U << (8U - shift); - PNG_CONST unsigned int max = (1U << (16U - shift))-1U; - unsigned int i; - png_uint_32 last; - - png_uint_16pp table = *ptable = - (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p))); - - /* 'num' is the number of tables and also the number of low bits of low - * bits of the input 16-bit value used to select a table. Each table is - * itself indexed by the high 8 bits of the value. - */ - for (i = 0; i < num; i++) - table[i] = (png_uint_16p)png_malloc(png_ptr, - 256 * (sizeof (png_uint_16))); - - /* 'gamma_val' is set to the reciprocal of the value calculated above, so - * pow(out,g) is an *input* value. 'last' is the last input value set. - * - * In the loop 'i' is used to find output values. Since the output is - * 8-bit there are only 256 possible values. The tables are set up to - * select the closest possible output value for each input by finding - * the input value at the boundary between each pair of output values - * and filling the table up to that boundary with the lower output - * value. - * - * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit - * values the code below uses a 16-bit value in i; the values start at - * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last - * entries are filled with 255). Start i at 128 and fill all 'last' - * table entries <= 'max' - */ - last = 0; - for (i = 0; i < 255; ++i) /* 8-bit output value */ - { - /* Find the corresponding maximum input value */ - png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */ - - /* Find the boundary value in 16 bits: */ - png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val); - - /* Adjust (round) to (16-shift) bits: */ - bound = (bound * max + 32768U)/65535U + 1U; - - while (last < bound) - { - table[last & (0xffU >> shift)][last >> (8U - shift)] = out; - last++; - } - } - - /* And fill in the final entries. */ - while (last < (num << 8)) - { - table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U; - last++; - } -} -#endif /* 16BIT */ - -/* Build a single 8-bit table: same as the 16-bit case but much simpler (and - * typically much faster). Note that libpng currently does no sBIT processing - * (apparently contrary to the spec) so a 256-entry table is always generated. - */ -static void -png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable, - PNG_CONST png_fixed_point gamma_val) -{ - unsigned int i; - png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256); - - if (png_gamma_significant(gamma_val) != 0) - for (i=0; i<256; i++) - table[i] = png_gamma_8bit_correct(i, gamma_val); - - else - for (i=0; i<256; ++i) - table[i] = (png_byte)(i & 0xff); -} - -/* Used from png_read_destroy and below to release the memory used by the gamma - * tables. - */ -void /* PRIVATE */ -png_destroy_gamma_table(png_structrp png_ptr) -{ - png_free(png_ptr, png_ptr->gamma_table); - png_ptr->gamma_table = NULL; - -#ifdef PNG_16BIT_SUPPORTED - if (png_ptr->gamma_16_table != NULL) - { - int i; - int istop = (1 << (8 - png_ptr->gamma_shift)); - for (i = 0; i < istop; i++) - { - png_free(png_ptr, png_ptr->gamma_16_table[i]); - } - png_free(png_ptr, png_ptr->gamma_16_table); - png_ptr->gamma_16_table = NULL; - } -#endif /* 16BIT */ - -#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ - defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ - defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) - png_free(png_ptr, png_ptr->gamma_from_1); - png_ptr->gamma_from_1 = NULL; - png_free(png_ptr, png_ptr->gamma_to_1); - png_ptr->gamma_to_1 = NULL; - -#ifdef PNG_16BIT_SUPPORTED - if (png_ptr->gamma_16_from_1 != NULL) - { - int i; - int istop = (1 << (8 - png_ptr->gamma_shift)); - for (i = 0; i < istop; i++) - { - png_free(png_ptr, png_ptr->gamma_16_from_1[i]); - } - png_free(png_ptr, png_ptr->gamma_16_from_1); - png_ptr->gamma_16_from_1 = NULL; - } - if (png_ptr->gamma_16_to_1 != NULL) - { - int i; - int istop = (1 << (8 - png_ptr->gamma_shift)); - for (i = 0; i < istop; i++) - { - png_free(png_ptr, png_ptr->gamma_16_to_1[i]); - } - png_free(png_ptr, png_ptr->gamma_16_to_1); - png_ptr->gamma_16_to_1 = NULL; - } -#endif /* 16BIT */ -#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ -} - -/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit - * tables, we don't make a full table if we are reducing to 8-bit in - * the future. Note also how the gamma_16 tables are segmented so that - * we don't need to allocate > 64K chunks for a full 16-bit table. - */ -void /* PRIVATE */ -png_build_gamma_table(png_structrp png_ptr, int bit_depth) -{ - png_debug(1, "in png_build_gamma_table"); - - /* Remove any existing table; this copes with multiple calls to - * png_read_update_info. The warning is because building the gamma tables - * multiple times is a performance hit - it's harmless but the ability to call - * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible - * to warn if the app introduces such a hit. - */ - if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL) - { - png_warning(png_ptr, "gamma table being rebuilt"); - png_destroy_gamma_table(png_ptr); - } - - if (bit_depth <= 8) - { - png_build_8bit_table(png_ptr, &png_ptr->gamma_table, - png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma, - png_ptr->screen_gamma) : PNG_FP_1); - -#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ - defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ - defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) - if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0) - { - png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1, - png_reciprocal(png_ptr->colorspace.gamma)); - - png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1, - png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : - png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */); - } -#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ - } -#ifdef PNG_16BIT_SUPPORTED - else - { - png_byte shift, sig_bit; - - if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) - { - sig_bit = png_ptr->sig_bit.red; - - if (png_ptr->sig_bit.green > sig_bit) - sig_bit = png_ptr->sig_bit.green; - - if (png_ptr->sig_bit.blue > sig_bit) - sig_bit = png_ptr->sig_bit.blue; - } - else - sig_bit = png_ptr->sig_bit.gray; - - /* 16-bit gamma code uses this equation: - * - * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8] - * - * Where 'iv' is the input color value and 'ov' is the output value - - * pow(iv, gamma). - * - * Thus the gamma table consists of up to 256 256-entry tables. The table - * is selected by the (8-gamma_shift) most significant of the low 8 bits of - * the color value then indexed by the upper 8 bits: - * - * table[low bits][high 8 bits] - * - * So the table 'n' corresponds to all those 'iv' of: - * - * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1> - * - */ - if (sig_bit > 0 && sig_bit < 16U) - /* shift == insignificant bits */ - shift = (png_byte)((16U - sig_bit) & 0xff); - - else - shift = 0; /* keep all 16 bits */ - - if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0) - { - /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively - * the significant bits in the *input* when the output will - * eventually be 8 bits. By default it is 11. - */ - if (shift < (16U - PNG_MAX_GAMMA_8)) - shift = (16U - PNG_MAX_GAMMA_8); - } - - if (shift > 8U) - shift = 8U; /* Guarantees at least one table! */ - - png_ptr->gamma_shift = shift; - - /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now - * PNG_COMPOSE). This effectively smashed the background calculation for - * 16-bit output because the 8-bit table assumes the result will be reduced - * to 8 bits. - */ - if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0) - png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift, - png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma, - png_ptr->screen_gamma) : PNG_FP_1); - - else - png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift, - png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma, - png_ptr->screen_gamma) : PNG_FP_1); - -#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ - defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ - defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) - if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0) - { - png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift, - png_reciprocal(png_ptr->colorspace.gamma)); - - /* Notice that the '16 from 1' table should be full precision, however - * the lookup on this table still uses gamma_shift, so it can't be. - * TODO: fix this. - */ - png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift, - png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : - png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */); - } -#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ - } -#endif /* 16BIT */ -} -#endif /* READ_GAMMA */ - -/* HARDWARE OR SOFTWARE OPTION SUPPORT */ -#ifdef PNG_SET_OPTION_SUPPORTED -int PNGAPI -png_set_option(png_structrp png_ptr, int option, int onoff) -{ - if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT && - (option & 1) == 0) - { - int mask = 3 << option; - int setting = (2 + (onoff != 0)) << option; - int current = png_ptr->options; - - png_ptr->options = (png_byte)(((current & ~mask) | setting) & 0xff); - - return (current & mask) >> option; - } - - return PNG_OPTION_INVALID; -} -#endif - -/* sRGB support */ -#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\ - defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) -/* sRGB conversion tables; these are machine generated with the code in - * contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the - * specification (see the article at http://en.wikipedia.org/wiki/SRGB) - * is used, not the gamma=1/2.2 approximation use elsewhere in libpng. - * The sRGB to linear table is exact (to the nearest 16-bit linear fraction). - * The inverse (linear to sRGB) table has accuracies as follows: - * - * For all possible (255*65535+1) input values: - * - * error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact - * - * For the input values corresponding to the 65536 16-bit values: - * - * error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact - * - * In all cases the inexact readings are only off by one. - */ - -#ifdef PNG_SIMPLIFIED_READ_SUPPORTED -/* The convert-to-sRGB table is only currently required for read. */ -const png_uint_16 png_sRGB_table[256] = -{ - 0,20,40,60,80,99,119,139, - 159,179,199,219,241,264,288,313, - 340,367,396,427,458,491,526,562, - 599,637,677,718,761,805,851,898, - 947,997,1048,1101,1156,1212,1270,1330, - 1391,1453,1517,1583,1651,1720,1790,1863, - 1937,2013,2090,2170,2250,2333,2418,2504, - 2592,2681,2773,2866,2961,3058,3157,3258, - 3360,3464,3570,3678,3788,3900,4014,4129, - 4247,4366,4488,4611,4736,4864,4993,5124, - 5257,5392,5530,5669,5810,5953,6099,6246, - 6395,6547,6700,6856,7014,7174,7335,7500, - 7666,7834,8004,8177,8352,8528,8708,8889, - 9072,9258,9445,9635,9828,10022,10219,10417, - 10619,10822,11028,11235,11446,11658,11873,12090, - 12309,12530,12754,12980,13209,13440,13673,13909, - 14146,14387,14629,14874,15122,15371,15623,15878, - 16135,16394,16656,16920,17187,17456,17727,18001, - 18277,18556,18837,19121,19407,19696,19987,20281, - 20577,20876,21177,21481,21787,22096,22407,22721, - 23038,23357,23678,24002,24329,24658,24990,25325, - 25662,26001,26344,26688,27036,27386,27739,28094, - 28452,28813,29176,29542,29911,30282,30656,31033, - 31412,31794,32179,32567,32957,33350,33745,34143, - 34544,34948,35355,35764,36176,36591,37008,37429, - 37852,38278,38706,39138,39572,40009,40449,40891, - 41337,41785,42236,42690,43147,43606,44069,44534, - 45002,45473,45947,46423,46903,47385,47871,48359, - 48850,49344,49841,50341,50844,51349,51858,52369, - 52884,53401,53921,54445,54971,55500,56032,56567, - 57105,57646,58190,58737,59287,59840,60396,60955, - 61517,62082,62650,63221,63795,64372,64952,65535 -}; -#endif /* SIMPLIFIED_READ */ - -/* The base/delta tables are required for both read and write (but currently - * only the simplified versions.) - */ -const png_uint_16 png_sRGB_base[512] = -{ - 128,1782,3383,4644,5675,6564,7357,8074, - 8732,9346,9921,10463,10977,11466,11935,12384, - 12816,13233,13634,14024,14402,14769,15125,15473, - 15812,16142,16466,16781,17090,17393,17690,17981, - 18266,18546,18822,19093,19359,19621,19879,20133, - 20383,20630,20873,21113,21349,21583,21813,22041, - 22265,22487,22707,22923,23138,23350,23559,23767, - 23972,24175,24376,24575,24772,24967,25160,25352, - 25542,25730,25916,26101,26284,26465,26645,26823, - 27000,27176,27350,27523,27695,27865,28034,28201, - 28368,28533,28697,28860,29021,29182,29341,29500, - 29657,29813,29969,30123,30276,30429,30580,30730, - 30880,31028,31176,31323,31469,31614,31758,31902, - 32045,32186,32327,32468,32607,32746,32884,33021, - 33158,33294,33429,33564,33697,33831,33963,34095, - 34226,34357,34486,34616,34744,34873,35000,35127, - 35253,35379,35504,35629,35753,35876,35999,36122, - 36244,36365,36486,36606,36726,36845,36964,37083, - 37201,37318,37435,37551,37668,37783,37898,38013, - 38127,38241,38354,38467,38580,38692,38803,38915, - 39026,39136,39246,39356,39465,39574,39682,39790, - 39898,40005,40112,40219,40325,40431,40537,40642, - 40747,40851,40955,41059,41163,41266,41369,41471, - 41573,41675,41777,41878,41979,42079,42179,42279, - 42379,42478,42577,42676,42775,42873,42971,43068, - 43165,43262,43359,43456,43552,43648,43743,43839, - 43934,44028,44123,44217,44311,44405,44499,44592, - 44685,44778,44870,44962,45054,45146,45238,45329, - 45420,45511,45601,45692,45782,45872,45961,46051, - 46140,46229,46318,46406,46494,46583,46670,46758, - 46846,46933,47020,47107,47193,47280,47366,47452, - 47538,47623,47709,47794,47879,47964,48048,48133, - 48217,48301,48385,48468,48552,48635,48718,48801, - 48884,48966,49048,49131,49213,49294,49376,49458, - 49539,49620,49701,49782,49862,49943,50023,50103, - 50183,50263,50342,50422,50501,50580,50659,50738, - 50816,50895,50973,51051,51129,51207,51285,51362, - 51439,51517,51594,51671,51747,51824,51900,51977, - 52053,52129,52205,52280,52356,52432,52507,52582, - 52657,52732,52807,52881,52956,53030,53104,53178, - 53252,53326,53400,53473,53546,53620,53693,53766, - 53839,53911,53984,54056,54129,54201,54273,54345, - 54417,54489,54560,54632,54703,54774,54845,54916, - 54987,55058,55129,55199,55269,55340,55410,55480, - 55550,55620,55689,55759,55828,55898,55967,56036, - 56105,56174,56243,56311,56380,56448,56517,56585, - 56653,56721,56789,56857,56924,56992,57059,57127, - 57194,57261,57328,57395,57462,57529,57595,57662, - 57728,57795,57861,57927,57993,58059,58125,58191, - 58256,58322,58387,58453,58518,58583,58648,58713, - 58778,58843,58908,58972,59037,59101,59165,59230, - 59294,59358,59422,59486,59549,59613,59677,59740, - 59804,59867,59930,59993,60056,60119,60182,60245, - 60308,60370,60433,60495,60558,60620,60682,60744, - 60806,60868,60930,60992,61054,61115,61177,61238, - 61300,61361,61422,61483,61544,61605,61666,61727, - 61788,61848,61909,61969,62030,62090,62150,62211, - 62271,62331,62391,62450,62510,62570,62630,62689, - 62749,62808,62867,62927,62986,63045,63104,63163, - 63222,63281,63340,63398,63457,63515,63574,63632, - 63691,63749,63807,63865,63923,63981,64039,64097, - 64155,64212,64270,64328,64385,64443,64500,64557, - 64614,64672,64729,64786,64843,64900,64956,65013, - 65070,65126,65183,65239,65296,65352,65409,65465 -}; - -const png_byte png_sRGB_delta[512] = -{ - 207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54, - 52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36, - 35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28, - 28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24, - 23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21, - 21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19, - 19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17, - 17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16, - 16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15, - 15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14, - 14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13, - 13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12, - 12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12, - 12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11, - 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11, - 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11, - 11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10, - 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10, - 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10, - 10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, - 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, - 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, - 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, - 9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, - 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, - 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, - 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, - 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, - 8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7, - 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, - 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, - 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 -}; -#endif /* SIMPLIFIED READ/WRITE sRGB support */ - -/* SIMPLIFIED READ/WRITE SUPPORT */ -#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\ - defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) -static int -png_image_free_function(png_voidp argument) -{ - png_imagep image = png_voidcast(png_imagep, argument); - png_controlp cp = image->opaque; - png_control c; - - /* Double check that we have a png_ptr - it should be impossible to get here - * without one. - */ - if (cp->png_ptr == NULL) - return 0; - - /* First free any data held in the control structure. */ -# ifdef PNG_STDIO_SUPPORTED - if (cp->owned_file != 0) - { - FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr); - cp->owned_file = 0; - - /* Ignore errors here. */ - if (fp != NULL) - { - cp->png_ptr->io_ptr = NULL; - (void)fclose(fp); - } - } -# endif - - /* Copy the control structure so that the original, allocated, version can be - * safely freed. Notice that a png_error here stops the remainder of the - * cleanup, but this is probably fine because that would indicate bad memory - * problems anyway. - */ - c = *cp; - image->opaque = &c; - png_free(c.png_ptr, cp); - - /* Then the structures, calling the correct API. */ - if (c.for_write != 0) - { -# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED - png_destroy_write_struct(&c.png_ptr, &c.info_ptr); -# else - png_error(c.png_ptr, "simplified write not supported"); -# endif - } - else - { -# ifdef PNG_SIMPLIFIED_READ_SUPPORTED - png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL); -# else - png_error(c.png_ptr, "simplified read not supported"); -# endif - } - - /* Success. */ - return 1; -} - -void PNGAPI -png_image_free(png_imagep image) -{ - /* Safely call the real function, but only if doing so is safe at this point - * (if not inside an error handling context). Otherwise assume - * png_safe_execute will call this API after the return. - */ - if (image != NULL && image->opaque != NULL && - image->opaque->error_buf == NULL) - { - /* Ignore errors here: */ - (void)png_safe_execute(image, png_image_free_function, image); - image->opaque = NULL; - } -} - -int /* PRIVATE */ -png_image_error(png_imagep image, png_const_charp error_message) -{ - /* Utility to log an error. */ - png_safecat(image->message, (sizeof image->message), 0, error_message); - image->warning_or_error |= PNG_IMAGE_ERROR; - png_image_free(image); - return 0; -} - -#endif /* SIMPLIFIED READ/WRITE */ -#endif /* READ || WRITE */ |