| 1 | |
| 2 | /* pngwio.c - functions for data output |
| 3 | * |
| 4 | * libpng 1.0.3 - January 14, 1999 |
| 5 | * For conditions of distribution and use, see copyright notice in png.h |
| 6 | * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. |
| 7 | * Copyright (c) 1996, 1997 Andreas Dilger |
| 8 | * Copyright (c) 1998, 1999 Glenn Randers-Pehrson |
| 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 | |
| 21 | /* Write the data to whatever output you are using. The default routine |
| 22 | writes to a file pointer. Note that this routine sometimes gets called |
| 23 | with very small lengths, so you should implement some kind of simple |
| 24 | buffering if you are using unbuffered writes. This should never be asked |
| 25 | to write more than 64K on a 16 bit machine. */ |
| 26 | |
| 27 | void |
| 28 | png_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| 29 | { |
| 30 | if (png_ptr->write_data_fn != NULL ) |
| 31 | (*(png_ptr->write_data_fn))(png_ptr, data, length); |
| 32 | else |
| 33 | png_error(png_ptr, "Call to NULL write function"); |
| 34 | } |
| 35 | |
| 36 | #if !defined(PNG_NO_STDIO) |
| 37 | /* This is the function that does the actual writing of data. If you are |
| 38 | not writing to a standard C stream, you should create a replacement |
| 39 | write_data function and use it at run time with png_set_write_fn(), rather |
| 40 | than changing the library. */ |
| 41 | #ifndef USE_FAR_KEYWORD |
| 42 | #ifdef __VISAGECPP__ |
| 43 | static void _Optlink |
| 44 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| 45 | #else |
| 46 | static void |
| 47 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| 48 | #endif |
| 49 | { |
| 50 | png_uint_32 check; |
| 51 | |
| 52 | check = fwrite(data, 1, length, (FILE *)(png_ptr->io_ptr)); |
| 53 | if (check != length) |
| 54 | { |
| 55 | png_error(png_ptr, "Write Error"); |
| 56 | } |
| 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 | #ifdef __VISAGECPP__ |
| 68 | static void _Optlink |
| 69 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| 70 | #else |
| 71 | static void |
| 72 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| 73 | #endif |
| 74 | { |
| 75 | png_uint_32 check; |
| 76 | png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */ |
| 77 | FILE *io_ptr; |
| 78 | |
| 79 | /* Check if data really is near. If so, use usual code. */ |
| 80 | near_data = (png_byte *)CVT_PTR_NOCHECK(data); |
| 81 | io_ptr = (FILE *)CVT_PTR(png_ptr->io_ptr); |
| 82 | if ((png_bytep)near_data == data) |
| 83 | { |
| 84 | check = fwrite(near_data, 1, length, io_ptr); |
| 85 | } |
| 86 | else |
| 87 | { |
| 88 | png_byte buf[NEAR_BUF_SIZE]; |
| 89 | png_size_t written, remaining, err; |
| 90 | check = 0; |
| 91 | remaining = length; |
| 92 | do |
| 93 | { |
| 94 | written = MIN(NEAR_BUF_SIZE, remaining); |
| 95 | png_memcpy(buf, data, written); /* copy far buffer to near buffer */ |
| 96 | err = fwrite(buf, 1, written, io_ptr); |
| 97 | if (err != written) |
| 98 | break; |
| 99 | else |
| 100 | check += err; |
| 101 | data += written; |
| 102 | remaining -= written; |
| 103 | } |
| 104 | while (remaining != 0); |
| 105 | } |
| 106 | if (check != length) |
| 107 | { |
| 108 | png_error(png_ptr, "Write Error"); |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | #endif |
| 113 | #endif |
| 114 | |
| 115 | /* This function is called to output any data pending writing (normally |
| 116 | to disk). After png_flush is called, there should be no data pending |
| 117 | writing in any buffers. */ |
| 118 | #if defined(PNG_WRITE_FLUSH_SUPPORTED) |
| 119 | void |
| 120 | png_flush(png_structp png_ptr) |
| 121 | { |
| 122 | if (png_ptr->output_flush_fn != NULL) |
| 123 | (*(png_ptr->output_flush_fn))(png_ptr); |
| 124 | } |
| 125 | |
| 126 | #if !defined(PNG_NO_STDIO) |
| 127 | #ifdef __VISAGECPP__ |
| 128 | static void _Optlink |
| 129 | png_default_flush(png_structp png_ptr) |
| 130 | #else |
| 131 | static void |
| 132 | png_default_flush(png_structp png_ptr) |
| 133 | #endif |
| 134 | { |
| 135 | FILE *io_ptr; |
| 136 | io_ptr = (FILE *)CVT_PTR((png_ptr->io_ptr)); |
| 137 | if (io_ptr != NULL) |
| 138 | fflush(io_ptr); |
| 139 | } |
| 140 | #endif |
| 141 | #endif |
| 142 | |
| 143 | /* This function allows the application to supply new output functions for |
| 144 | libpng if standard C streams aren't being used. |
| 145 | |
| 146 | This function takes as its arguments: |
| 147 | png_ptr - pointer to a png output data structure |
| 148 | io_ptr - pointer to user supplied structure containing info about |
| 149 | the output functions. May be NULL. |
| 150 | write_data_fn - pointer to a new output function that takes as its |
| 151 | arguments a pointer to a png_struct, a pointer to |
| 152 | data to be written, and a 32-bit unsigned int that is |
| 153 | the number of bytes to be written. The new write |
| 154 | function should call png_error(png_ptr, "Error msg") |
| 155 | to exit and output any fatal error messages. |
| 156 | flush_data_fn - pointer to a new flush function that takes as its |
| 157 | arguments a pointer to a png_struct. After a call to |
| 158 | the flush function, there should be no data in any buffers |
| 159 | or pending transmission. If the output method doesn't do |
| 160 | any buffering of ouput, a function prototype must still be |
| 161 | supplied although it doesn't have to do anything. If |
| 162 | PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile |
| 163 | time, output_flush_fn will be ignored, although it must be |
| 164 | supplied for compatibility. */ |
| 165 | void |
| 166 | png_set_write_fn(png_structp png_ptr, png_voidp io_ptr, |
| 167 | png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn) |
| 168 | { |
| 169 | png_ptr->io_ptr = io_ptr; |
| 170 | |
| 171 | #if !defined(PNG_NO_STDIO) |
| 172 | if (write_data_fn != NULL) |
| 173 | png_ptr->write_data_fn = write_data_fn; |
| 174 | else |
| 175 | png_ptr->write_data_fn = png_default_write_data; |
| 176 | #else |
| 177 | png_ptr->write_data_fn = write_data_fn; |
| 178 | #endif |
| 179 | |
| 180 | #if defined(PNG_WRITE_FLUSH_SUPPORTED) |
| 181 | #if !defined(PNG_NO_STDIO) |
| 182 | if (output_flush_fn != NULL) |
| 183 | png_ptr->output_flush_fn = output_flush_fn; |
| 184 | else |
| 185 | png_ptr->output_flush_fn = png_default_flush; |
| 186 | #else |
| 187 | png_ptr->output_flush_fn = output_flush_fn; |
| 188 | #endif |
| 189 | #endif /* PNG_WRITE_FLUSH_SUPPORTED */ |
| 190 | |
| 191 | /* It is an error to read while writing a png file */ |
| 192 | if (png_ptr->read_data_fn != NULL) |
| 193 | { |
| 194 | png_ptr->read_data_fn = NULL; |
| 195 | png_warning(png_ptr, |
| 196 | "Attempted to set both read_data_fn and write_data_fn in"); |
| 197 | png_warning(png_ptr, |
| 198 | "the same structure. Resetting read_data_fn to NULL."); |
| 199 | } |
| 200 | } |
| 201 | |
| 202 | #if defined(USE_FAR_KEYWORD) |
| 203 | #if defined(_MSC_VER) |
| 204 | void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) |
| 205 | { |
| 206 | void *near_ptr; |
| 207 | void FAR *far_ptr; |
| 208 | FP_OFF(near_ptr) = FP_OFF(ptr); |
| 209 | far_ptr = (void FAR *)near_ptr; |
| 210 | if(check != 0) |
| 211 | if(FP_SEG(ptr) != FP_SEG(far_ptr)) |
| 212 | png_error(png_ptr,"segment lost in conversion"); |
| 213 | return(near_ptr); |
| 214 | } |
| 215 | # else |
| 216 | void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) |
| 217 | { |
| 218 | void *near_ptr; |
| 219 | void FAR *far_ptr; |
| 220 | near_ptr = (void FAR *)ptr; |
| 221 | far_ptr = (void FAR *)near_ptr; |
| 222 | if(check != 0) |
| 223 | if(far_ptr != ptr) |
| 224 | png_error(png_ptr,"segment lost in conversion"); |
| 225 | return(near_ptr); |
| 226 | } |
| 227 | # endif |
| 228 | # endif |