| |
| /* 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 |
| <