png.c Go to the documentation of this file. /* png.c - location for general purpose libpng functions * * libpng version 1.0.12 - June 8, 2001 * Copyright (c) 1998-2001 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.) * */ #define PNG_INTERNAL #define PNG_NO_EXTERN #include "png.h" /* Generate a compiler error if there is an old png.h in the search path. */ typedef version_1_0_12 Your_png_h_is_not_version_1_0_12; /* Version information for C files. This had better match the version * string defined in png.h. */ #ifdef PNG_USE_GLOBAL_ARRAYS /* png_libpng_ver was changed to a function in version 1.0.5c */ const char png_libpng_ver[18] = "1.0.12"; /* png_sig was changed to a function in version 1.0.5c */ /* Place to hold the signature string for a PNG file. */ const png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10}; /* Invoke global declarations for constant strings for known chunk types */ PNG_IHDR; PNG_IDAT; PNG_IEND; PNG_PLTE; PNG_bKGD; PNG_cHRM; PNG_gAMA; PNG_hIST; PNG_iCCP; PNG_iTXt; PNG_oFFs; PNG_pCAL; PNG_sCAL; PNG_pHYs; PNG_sBIT; PNG_sPLT; PNG_sRGB; PNG_tEXt; PNG_tIME; PNG_tRNS; PNG_zTXt; /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */ /* start of interlace block */ const int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; /* offset to next interlace block */ const int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; /* start of interlace block in the y direction */ const int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1}; /* offset to next interlace block in the y direction */ const int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2}; /* width of interlace block (used in assembler routines only) */ #ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW const int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1}; #endif /* Height of interlace block. This is not currently used - if you need * it, uncomment it here and in png.h const int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1}; */ /* Mask to determine which pixels are valid in a pass */ const int FARDATA png_pass_mask[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff}; /* Mask to determine which pixels to overwrite while displaying */ const int FARDATA png_pass_dsp_mask[] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff}; #endif /* 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 PNGAPI 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 = (png_byte)(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 PNGAPI png_sig_cmp(png_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 (0); if (start > 7) return (0); if (start + num_to_check > 8) num_to_check = 8 - start; return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check))); } /* (Obsolete) function to check signature bytes. It does not allow one * to check a partial signature. This function might be removed in the * future - use png_sig_cmp(). Returns true (nonzero) if the file is a PNG. */ int PNGAPI 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 and clear it to 0. */ voidpf /* PRIVATE */ png_zalloc(voidpf png_ptr, uInt items, uInt size) { png_uint_32 num_bytes = (png_uint_32)items * size; png_voidp ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes); #ifndef PNG_NO_ZALLOC_ZERO if (num_bytes > (png_uint_32)0x8000L) { 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); } #endif return ((voidpf)ptr); } /* function to free memory for zlib */ void /* PRIVATE */ 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 /* PRIVATE */ 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 /* PRIVATE */ 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, (uInt)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 PNGAPI 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); #ifdef PNG_USER_MEM_SUPPORTED if ((info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO, png_ptr->malloc_fn, png_ptr->mem_ptr)) != NULL) #else if ((info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO)) != NULL) #endif { png_info_init_3(&info_ptr, sizeof(png_info)); } 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 PNGAPI 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); #ifdef PNG_USER_MEM_SUPPORTED png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn, png_ptr->mem_ptr); #else png_destroy_struct((png_voidp)info_ptr); #endif *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. */ #undef png_info_init void PNGAPI png_info_init(png_infop info_ptr) { /* We only come here via pre-1.0.12-compiled applications */ png_info_init_3(&info_ptr, 0); } void PNGAPI png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size) { png_infop info_ptr = *ptr_ptr; png_debug(1, "in png_info_init_3\n"); if(sizeof(png_info) > png_info_struct_size) { png_destroy_struct(info_ptr); info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO); *ptr_ptr = info_ptr; } /* set everything to 0 */ png_memset(info_ptr, 0, sizeof (png_info)); } #ifdef PNG_FREE_ME_SUPPORTED void PNGAPI png_data_freer(png_structp png_ptr, png_infop info_ptr, int freer, png_uint_32 mask) { png_debug(1, "in png_data_freer\n"); 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_warning(png_ptr, "Unknown freer parameter in png_data_freer."); } #endif void PNGAPI png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask, int num) { png_debug(1, "in png_free_data\n"); if (png_ptr == NULL || info_ptr == NULL) return; #if defined(PNG_TEXT_SUPPORTED) /* free text item num or (if num == -1) all text items */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_TEXT) & info_ptr->free_me) #else if (mask & PNG_FREE_TEXT) #endif { if (num != -1) { if (info_ptr->text && info_ptr->text[num].key) { 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_data(png_ptr, info_ptr, PNG_FREE_TEXT, i); png_free(png_ptr, info_ptr->text); info_ptr->text = NULL; info_ptr->num_text=0; } } #endif #if defined(PNG_tRNS_SUPPORTED) /* free any tRNS entry */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_TRNS) & info_ptr->free_me) #else if ((mask & PNG_FREE_TRNS) && (png_ptr->flags & PNG_FLAG_FREE_TRNS)) #endif { png_free(png_ptr, info_ptr->trans); info_ptr->valid &= ~PNG_INFO_tRNS; info_ptr->trans = NULL; } #endif #if defined(PNG_sCAL_SUPPORTED) /* free any sCAL entry */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_SCAL) & info_ptr->free_me) #else if (mask & PNG_FREE_SCAL) #endif { #if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED) 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; #endif info_ptr->valid &= ~PNG_INFO_sCAL; } #endif #if defined(PNG_pCAL_SUPPORTED) /* free any pCAL entry */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_PCAL) & info_ptr->free_me) #else if (mask & PNG_FREE_PCAL) #endif { 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 < (int)info_ptr->pcal_nparams; i++) { png_free(png_ptr, info_ptr->pcal_params[i]); info_ptr->pcal_params[i]=NULL; } png_free(png_ptr, info_ptr->pcal_params); info_ptr->pcal_params = NULL; } info_ptr->valid &= ~PNG_INFO_pCAL; } #endif #if defined(PNG_iCCP_SUPPORTED) /* free any iCCP entry */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_ICCP) & info_ptr->free_me) #else if (mask & PNG_FREE_ICCP) #endif { 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 #if defined(PNG_sPLT_SUPPORTED) /* free a given sPLT entry, or (if num == -1) all sPLT entries */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_SPLT) & info_ptr->free_me) #else if (mask & PNG_FREE_SPLT) #endif { if (num != -1) { if(info_ptr->splt_palettes) { 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 { if(info_ptr->splt_palettes_num) { int i; for (i = 0; i < (int)info_ptr->splt_palettes_num; i++) png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i); 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 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_UNKN) & info_ptr->free_me) #else if (mask & PNG_FREE_UNKN) #endif { if (num != -1) { if(info_ptr->unknown_chunks) { png_free(png_ptr, info_ptr->unknown_chunks[num].data); info_ptr->unknown_chunks[num].data = NULL; } } else { int i; if(info_ptr->unknown_chunks_num) { for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++) png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i); png_free(png_ptr, info_ptr->unknown_chunks); info_ptr->unknown_chunks = NULL; info_ptr->unknown_chunks_num = 0; } } } #endif #if defined(PNG_hIST_SUPPORTED) /* free any hIST entry */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_HIST) & info_ptr->free_me) #else if ((mask & PNG_FREE_HIST) && (png_ptr->flags & PNG_FLAG_FREE_HIST)) #endif { 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 */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_PLTE) & info_ptr->free_me) #else if ((mask & PNG_FREE_PLTE) && (png_ptr->flags & PNG_FLAG_FREE_PLTE)) #endif { png_zfree(png_ptr, info_ptr->palette); info_ptr->palette = NULL; info_ptr->valid &= ~PNG_INFO_PLTE; info_ptr->num_palette = 0; } #if defined(PNG_INFO_IMAGE_SUPPORTED) /* free any image bits attached to the info structure */ #ifdef PNG_FREE_ME_SUPPORTED if ((mask & PNG_FREE_ROWS) & info_ptr->free_me) #else if (mask & PNG_FREE_ROWS) #endif { if(info_ptr->row_pointers) { int row; for (row = 0; row < (int)info_ptr->height; row++) { png_free(png_ptr, info_ptr->row_pointers[row]); info_ptr->row_pointers[row]=NULL; } png_free(png_ptr, info_ptr->row_pointers); info_ptr->row_pointers=NULL; } info_ptr->valid &= ~PNG_INFO_IDAT; } #endif #ifdef PNG_FREE_ME_SUPPORTED if(num == -1) info_ptr->free_me &= ~mask; else info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL); #endif } /* 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 /* PRIVATE */ png_info_destroy(png_structp png_ptr, png_infop info_ptr) { png_debug(1, "in png_info_destroy\n"); png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1); #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) if (png_ptr->num_chunk_list) { png_free(png_ptr, png_ptr->chunk_list); png_ptr->chunk_list=NULL; png_ptr->num_chunk_list=0; } #endif png_info_init_3(&info_ptr, sizeof(png_info)); } /* 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_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(). If you have defined * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't * necessarily available. */ void PNGAPI png_init_io(png_structp png_ptr, png_FILE_p fp) { png_debug(1, "in png_init_io\n"); png_ptr->io_ptr = (png_voidp)fp; } #endif #if defined(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. */ png_charp PNGAPI png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime) { static PNG_CONST char short_months[12][4] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; if (png_ptr->time_buffer == NULL) { png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29* sizeof(char))); } #if defined(_WIN32_WCE) { wchar_t time_buf[29]; wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"), ptime->day % 32, short_months[(ptime->month - 1) % 12], ptime->year, ptime->hour % 24, ptime->minute % 60, ptime->second % 61); WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer, 29, NULL, NULL); } #else #ifdef USE_FAR_KEYWORD { char near_time_buf[29]; sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000", ptime->day % 32, short_months[(ptime->month - 1) % 12], ptime->year, ptime->hour % 24, ptime->minute % 60, ptime->second % 61); png_memcpy(png_ptr->time_buffer, near_time_buf, 29*sizeof(char)); } #else sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000", ptime->day % 32, short_months[(ptime->month - 1) % 12], ptime->year, ptime->hour % 24, ptime->minute % 60, ptime->second % 61); #endif #endif /* _WIN32_WCE */ return ((png_charp)png_ptr->time_buffer); } #endif /* PNG_TIME_RFC1123_SUPPORTED */ #if 0 /* Signature string for a PNG file. */ png_bytep PNGAPI png_sig_bytes(void) { return ((png_bytep)"\211\120\116\107\015\012\032\012"); } #endif png_charp PNGAPI png_get_copyright(png_structp png_ptr) { if (png_ptr != NULL || png_ptr == NULL) /* silence compiler warning */ return ((png_charp) "\n libpng version 1.0.12 - June 8, 2001\n\ Copyright (c) 1998-2001 Glenn Randers-Pehrson\n\ Copyright (c) 1996, 1997 Andreas Dilger\n\ Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.\n"); return ((png_charp) ""); } /* 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. */ png_charp PNGAPI png_get_libpng_ver(png_structp png_ptr) { /* Version of *.c files used when building libpng */ if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */ return((png_charp) "1.0.12"); return((png_charp) "1.0.12"); } png_charp PNGAPI png_get_header_ver(png_structp png_ptr) { /* Version of *.h files used when building libpng */ if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */ return((png_charp) PNG_LIBPNG_VER_STRING); return((png_charp) PNG_LIBPNG_VER_STRING); } png_charp PNGAPI png_get_header_version(png_structp png_ptr) { /* Returns longer string containing both version and date */ if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */ return((png_charp) PNG_HEADER_VERSION_STRING); return((png_charp) PNG_HEADER_VERSION_STRING); } #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED int /* PRIVATE */ png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name) { /* check chunk_name and return "keep" value if it's on the list, else 0 */ int i; png_bytep p; if((png_ptr == NULL && chunk_name == NULL) || png_ptr->num_chunk_list<=0) return 0; p=png_ptr->chunk_list+png_ptr->num_chunk_list*5-5; for (i = png_ptr->num_chunk_list; i; i--, p-=5) if (!png_memcmp(chunk_name, p, 4)) return ((int)*(p+4)); return 0; } #endif /* This function, added to libpng-1.0.6g, is untested. */ int PNGAPI png_reset_zstream(png_structp png_ptr) { return (inflateReset(&png_ptr->zstream)); } /* 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) 10012L); } /* this function was added to libpng 1.2.0 */ #if !defined(PNG_USE_PNGGCCRD) && \ !(defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_USE_PNGVCRD)) int PNGAPI png_mmx_support(void) { return -1; } #endif