1 2 /* pngwio.c - functions for data output 3 * 4 * Last changed in libpng 1.2.13 November 13, 2006 5 * For conditions of distribution and use, see copyright notice in png.h 6 * Copyright (c) 1998-2006 Glenn Randers-Pehrson 7 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) 8 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 9 * 10 * This file provides a location for all output. Users who need 11 * special handling are expected to write functions that have the same 12 * arguments as these and perform similar functions, but that possibly 13 * use different output methods. Note that you shouldn't change these 14 * functions, but rather write replacement functions and then change 15 * them at run time with png_set_write_fn(...). 16 */ 17 18 #define PNG_INTERNAL 19 #include "png.h" 20 #ifdef PNG_WRITE_SUPPORTED 21 22 /* Write the data to whatever output you are using. The default routine 23 writes to a file pointer. Note that this routine sometimes gets called 24 with very small lengths, so you should implement some kind of simple 25 buffering if you are using unbuffered writes. This should never be asked 26 to write more than 64K on a 16 bit machine. */ 27 28 void /* PRIVATE */ 29 png_write_data(png_structp png_ptr, png_bytep data, png_size_t length) 30 { 31 if (png_ptr->write_data_fn != NULL ) 32 (*(png_ptr->write_data_fn))(png_ptr, data, length); 33 else 34 png_error(png_ptr, "Call to NULL write function"); 35 } 36 37 #if !defined(PNG_NO_STDIO) 38 /* This is the function that does the actual writing of data. If you are 39 not writing to a standard C stream, you should create a replacement 40 write_data function and use it at run time with png_set_write_fn(), rather 41 than changing the library. */ 42 #ifndef USE_FAR_KEYWORD 43 void PNGAPI 44 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) 45 { 46 png_uint_32 check; 47 48 if(png_ptr == NULL) return; 49 #if defined(_WIN32_WCE) 50 if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) ) 51 check = 0; 52 #else 53 check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr)); 54 #endif 55 if (check != length) 56 png_error(png_ptr, "Write Error"); 57 } 58 #else 59 /* this is the model-independent version. Since the standard I/O library 60 can't handle far buffers in the medium and small models, we have to copy 61 the data. 62 */ 63 64 #define NEAR_BUF_SIZE 1024 65 #define MIN(a,b) (a <= b ? a : b) 66 67 void PNGAPI 68 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) 69 { 70 png_uint_32 check; 71 png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */ 72 png_FILE_p io_ptr; 73 74 if(png_ptr == NULL) return; 75 /* Check if data really is near. If so, use usual code. */ 76 near_data = (png_byte *)CVT_PTR_NOCHECK(data); 77 io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr); 78 if ((png_bytep)near_data == data) 79 { 80 #if defined(_WIN32_WCE) 81 if ( !WriteFile(io_ptr, near_data, length, &check, NULL) ) 82 check = 0; 83 #else 84 check = fwrite(near_data, 1, length, io_ptr); 85 #endif 86 } 87 else 88 { 89 png_byte buf[NEAR_BUF_SIZE]; 90 png_size_t written, remaining, err; 91 check = 0; 92 remaining = length; 93 do 94 { 95 written = MIN(NEAR_BUF_SIZE, remaining); 96 png_memcpy(buf, data, written); /* copy far buffer to near buffer */ 97 #if defined(_WIN32_WCE) 98 if ( !WriteFile(io_ptr, buf, written, &err, NULL) ) 99 err = 0; 100 #else 101 err = fwrite(buf, 1, written, io_ptr); 102 #endif 103 if (err != written) 104 break; 105 else 106 check += err; 107 data += written; 108 remaining -= written; 109 } 110 while (remaining != 0); 111 } 112 if (check != length) 113 png_error(png_ptr, "Write Error"); 114 } 115 116 #endif 117 #endif 118 119 /* This function is called to output any data pending writing (normally 120 to disk). After png_flush is called, there should be no data pending 121 writing in any buffers. */ 122 #if defined(PNG_WRITE_FLUSH_SUPPORTED) 123 void /* PRIVATE */ 124 png_flush(png_structp png_ptr) 125 { 126 if (png_ptr->output_flush_fn != NULL) 127 (*(png_ptr->output_flush_fn))(png_ptr); 128 } 129 130 #if !defined(PNG_NO_STDIO) 131 void PNGAPI 132 png_default_flush(png_structp png_ptr) 133 { 134 #if !defined(_WIN32_WCE) 135 png_FILE_p io_ptr; 136 #endif 137 if(png_ptr == NULL) return; 138 #if !defined(_WIN32_WCE) 139 io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr)); 140 if (io_ptr != NULL) 141 fflush(io_ptr); 142 #endif 143 } 144 #endif 145 #endif 146 147 /* This function allows the application to supply new output functions for 148 libpng if standard C streams aren't being used. 149 150 This function takes as its arguments: 151 png_ptr - pointer to a png output data structure 152 io_ptr - pointer to user supplied structure containing info about 153 the output functions. May be NULL. 154 write_data_fn - pointer to a new output function that takes as its 155 arguments a pointer to a png_struct, a pointer to 156 data to be written, and a 32-bit unsigned int that is 157 the number of bytes to be written. The new write 158 function should call png_error(png_ptr, "Error msg") 159 to exit and output any fatal error messages. 160 flush_data_fn - pointer to a new flush function that takes as its 161 arguments a pointer to a png_struct. After a call to 162 the flush function, there should be no data in any buffers 163 or pending transmission. If the output method doesn't do 164 any buffering of ouput, a function prototype must still be 165 supplied although it doesn't have to do anything. If 166 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile 167 time, output_flush_fn will be ignored, although it must be 168 supplied for compatibility. */ 169 void PNGAPI 170 png_set_write_fn(png_structp png_ptr, png_voidp io_ptr, 171 png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn) 172 { 173 if(png_ptr == NULL) return; 174 png_ptr->io_ptr = io_ptr; 175 176 #if !defined(PNG_NO_STDIO) 177 if (write_data_fn != NULL) 178 png_ptr->write_data_fn = write_data_fn; 179 else 180 png_ptr->write_data_fn = png_default_write_data; 181 #else 182 png_ptr->write_data_fn = write_data_fn; 183 #endif 184 185 #if defined(PNG_WRITE_FLUSH_SUPPORTED) 186 #if !defined(PNG_NO_STDIO) 187 if (output_flush_fn != NULL) 188 png_ptr->output_flush_fn = output_flush_fn; 189 else 190 png_ptr->output_flush_fn = png_default_flush; 191 #else 192 png_ptr->output_flush_fn = output_flush_fn; 193 #endif 194 #endif /* PNG_WRITE_FLUSH_SUPPORTED */ 195 196 /* It is an error to read while writing a png file */ 197 if (png_ptr->read_data_fn != NULL) 198 { 199 png_ptr->read_data_fn = NULL; 200 png_warning(png_ptr, 201 "Attempted to set both read_data_fn and write_data_fn in"); 202 png_warning(png_ptr, 203 "the same structure. Resetting read_data_fn to NULL."); 204 } 205 } 206 207 #if defined(USE_FAR_KEYWORD) 208 #if defined(_MSC_VER) 209 void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) 210 { 211 void *near_ptr; 212 void FAR *far_ptr; 213 FP_OFF(near_ptr) = FP_OFF(ptr); 214 far_ptr = (void FAR *)near_ptr; 215 if(check != 0) 216 if(FP_SEG(ptr) != FP_SEG(far_ptr)) 217 png_error(png_ptr,"segment lost in conversion"); 218 return(near_ptr); 219 } 220 # else 221 void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) 222 { 223 void *near_ptr; 224 void FAR *far_ptr; 225 near_ptr = (void FAR *)ptr; 226 far_ptr = (void FAR *)near_ptr; 227 if(check != 0) 228 if(far_ptr != ptr) 229 png_error(png_ptr,"segment lost in conversion"); 230 return(near_ptr); 231 } 232 # endif 233 # endif 234 #endif /* PNG_WRITE_SUPPORTED */ 235
