/* png.c - location for general purpose libpng functions * * libpng 0.99e * For conditions of distribution and use, see copyright notice in png.h * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. * Copyright (c) 1996, 1997 Andreas Dilger * Copyright (c) 1998, Glenn Randers-Pehrson * February 28, 1998 */ #define PNG_INTERNAL #define PNG_NO_EXTERN #include "png.h" /* Version information for C files. This had better match the version * string defined in png.h. */ char png_libpng_ver[5] = "0.99"; /* Place to hold the signature string for a PNG file. */ png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10}; /* Constant strings for known chunk types. If you need to add a chunk, * add a string holding the name here. If you want to make the code * portable to EBCDIC machines, use ASCII numbers, not characters. */ png_byte FARDATA png_IHDR[5] = { 73, 72, 68, 82, '\0'}; png_byte FARDATA png_IDAT[5] = { 73, 68, 65, 84, '\0'}; png_byte FARDATA png_IEND[5] = { 73, 69, 78, 68, '\0'}; png_byte FARDATA png_PLTE[5] = { 80, 76, 84, 69, '\0'}; png_byte FARDATA png_bKGD[5] = { 98, 75, 71, 68, '\0'}; png_byte FARDATA png_cHRM[5] = { 99, 72, 82, 77, '\0'}; png_byte FARDATA png_gAMA[5] = {103, 65, 77, 65, '\0'}; png_byte FARDATA png_hIST[5] = {104, 73, 83, 84, '\0'}; png_byte FARDATA png_oFFs[5] = {111, 70, 70, 115, '\0'}; png_byte FARDATA png_pCAL[5] = {112, 67, 65, 76, '\0'}; png_byte FARDATA png_pHYs[5] = {112, 72, 89, 115, '\0'}; png_byte FARDATA png_sBIT[5] = {115, 66, 73, 84, '\0'}; png_byte FARDATA png_sRGB[5] = {115, 82, 71, 66, '\0'}; png_byte FARDATA png_tEXt[5] = {116, 69, 88, 116, '\0'}; png_byte FARDATA png_tIME[5] = {116, 73, 77, 69, '\0'}; png_byte FARDATA png_tRNS[5] = {116, 82, 78, 83, '\0'}; png_byte FARDATA png_zTXt[5] = {122, 84, 88, 116, '\0'}; /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */ /* start of interlace block */ int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; /* offset to next interlace block */ int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; /* start of interlace block in the y direction */ int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1}; /* offset to next interlace block in the y direction */ int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2}; /* Width of interlace block. This is not currently used - if you need * it, uncomment it here and in png.h int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1}; */ /* Height of interlace block. This is not currently used - if you need * it, uncomment it here and in png.h int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1}; */ /* Mask to determine which pixels are valid in a pass */ int FARDATA png_pass_mask[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff}; /* Mask to determine which pixels to overwrite while displaying */ int FARDATA png_pass_dsp_mask[] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff}; /* 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. */ void png_set_sig_bytes(png_structp png_ptr, int num_bytes) { png_debug(1, "in png_set_sig_bytes\n"); if (num_bytes > 8) png_error(png_ptr, "Too many bytes for PNG signature."); png_ptr->sig_bytes = num_bytes < 0 ? 0 : num_bytes; } /* 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 behaviour as strcmp, memcmp, etc). */ int png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check) { if (num_to_check > 8) num_to_check = 8; else if (num_to_check < 1) return (0); if (start > 7) return (0); if (start + num_to_check > 8) num_to_check = 8 - start; return ((int)(png_memcmp(&sig[start], &png_sig[start], num_to_check))); } /* (Obsolete) function to check signature bytes. It does not allow one * to check a partial signature. This function will be removed in the * future - use png_sig_cmp(). */ int png_check_sig(png_bytep sig, int num) { return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num)); } /* Function to allocate memory for zlib. */ voidpf png_zalloc(voidpf png_ptr, uInt items, uInt size) { png_voidp ptr; png_uint_32 num_bytes; num_bytes = (png_uint_32)items * size; ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes); if (num_bytes > (png_uint_32)0x8000) { png_memset(ptr, 0, (png_size_t)0x8000L); png_memset((png_bytep)ptr + (png_size_t)0x8000L, 0, (png_size_t)(num_bytes - (png_uint_32)0x8000L)); } else { png_memset(ptr, 0, (png_size_t)num_bytes); } return ((voidpf)ptr); } /* function to free memory for zlib */ void png_zfree(voidpf png_ptr, voidpf ptr) { png_free((png_structp)png_ptr, (png_voidp)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 png_reset_crc(png_structp png_ptr) { png_ptr->crc = 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 png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length) { int need_crc = 1; if (png_ptr->chunk_name[0] & 0x20) /* ancillary */ { 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) need_crc = 0; } if (need_crc) png_ptr->crc = crc32(png_ptr->crc, ptr, length); } /* Allocate the memory for an info_struct for the application. We don't * really need the png_ptr, but it could potentially be useful in the * future. This should be used in favour of malloc(sizeof(png_info)) * and png_info_init() so that applications that want to use a shared * libpng don't have to be recompiled if png_info changes size. */ png_infop png_create_info_struct(png_structp png_ptr) { png_infop info_ptr; png_debug(1, "in png_create_info_struct\n"); if(png_ptr == NULL) return (NULL); if ((info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO)) != NULL) { png_info_init(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. */ void png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr) { png_infop info_ptr = NULL; png_debug(1, "in png_destroy_info_struct\n"); if (info_ptr_ptr != NULL) info_ptr = *info_ptr_ptr; if (info_ptr != NULL) { png_info_destroy(png_ptr, info_ptr); png_destroy_struct((png_voidp)info_ptr); *info_ptr_ptr = (png_infop)NULL; } } /* 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. */ void png_info_init(png_infop info_ptr) { png_debug(1, "in png_info_init\n"); /* set everything to 0 */ png_memset(info_ptr, 0, sizeof (png_info)); } /* This is an internal routine to free any memory that the info struct is * pointing to before re-using it or freeing the struct itself. Recall * that png_free() checks for NULL pointers for us. */ void png_info_destroy(png_structp png_ptr, png_infop info_ptr) { #if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED) int i; png_debug(1, "in png_info_destroy\n"); if (info_ptr->text != NULL) { 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); } #endif #if defined(PNG_READ_pCAL_SUPPORTED) png_free(png_ptr, info_ptr->pcal_purpose); png_free(png_ptr, info_ptr->pcal_units); if (info_ptr->pcal_params != NULL) { for (i = 0; i < (int)info_ptr->pcal_nparams; i++) { png_free(png_ptr, info_ptr->pcal_params[i]); } png_free(png_ptr, info_ptr->pcal_params); } #endif png_info_init(info_ptr); } /* 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 png_get_io_ptr(png_structp png_ptr) { return (png_ptr->io_ptr); } #if !defined(PNG_NO_STDIO) /* 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(). */ void png_init_io(png_structp png_ptr, FILE *fp) { png_debug(1, "in png_init_io\n"); png_ptr->io_ptr = (png_voidp)fp; } #endif