third_party/libpng/pngwio.c

   1
   2 /* pngwio.c - functions for data output
   3  *
   4  * Last changed in libpng 1.2.41 [December 3, 2009]
   5  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
   6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   8  *
   9  * This code is released under the libpng license.
  10  * For conditions of distribution and use, see the disclaimer
  11  * and license in png.h
  12  *
  13  * This file provides a location for all output.  Users who need
  14  * special handling are expected to write functions that have the same
  15  * arguments as these and perform similar functions, but that possibly
  16  * use different output methods.  Note that you shouldn't change these
  17  * functions, but rather write replacement functions and then change
  18  * them at run time with png_set_write_fn(...).
  19  */
  20
  21 #define PNG_INTERNAL
  22 #define PNG_NO_PEDANTIC_WARNINGS
  23 #include "png.h"
  24 #ifdef PNG_WRITE_SUPPORTED
  25
  26 /* Write the data to whatever output you are using.  The default routine
  27  * writes to a file pointer.  Note that this routine sometimes gets called
  28  * with very small lengths, so you should implement some kind of simple
  29  * buffering if you are using unbuffered writes.  This should never be asked
  30  * to write more than 64K on a 16 bit machine.
  31  */
  32
  33 void /* PRIVATE */
  34 png_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
  35 {
  36    if (png_ptr->write_data_fn != NULL )
  37       (*(png_ptr->write_data_fn))(png_ptr, data, length);
  38    else
  39       png_error(png_ptr, "Call to NULL write function");
  40 }
  41
  42 #ifdef PNG_STDIO_SUPPORTED
  43 /* This is the function that does the actual writing of data.  If you are
  44  * not writing to a standard C stream, you should create a replacement
  45  * write_data function and use it at run time with png_set_write_fn(), rather
  46  * than changing the library.
  47  */
  48 #ifndef USE_FAR_KEYWORD
  49 void PNGAPI
  50 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
  51 {
  52    png_uint_32 check;
  53
  54    if (png_ptr == NULL)
  55       return;
  56 #ifdef _WIN32_WCE
  57    if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
  58       check = 0;
  59 #else
  60    check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
  61 #endif
  62    if (check != length)
  63       png_error(png_ptr, "Write Error");
  64 }
  65 #else
  66 /* This is the model-independent version. Since the standard I/O library
  67  * can't handle far buffers in the medium and small models, we have to copy
  68  * the data.
  69  */
  70
  71 #define NEAR_BUF_SIZE 1024
  72 #define MIN(a,b) (a <= b ? a : b)
  73
  74 void PNGAPI
  75 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
  76 {
  77    png_uint_32 check;
  78    png_byte *near_data;  /* Needs to be "png_byte *" instead of "png_bytep" */
  79    png_FILE_p io_ptr;
  80
  81    if (png_ptr == NULL)
  82       return;
  83    /* Check if data really is near. If so, use usual code. */
  84    near_data = (png_byte *)CVT_PTR_NOCHECK(data);
  85    io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
  86    if ((png_bytep)near_data == data)
  87    {
  88 #ifdef _WIN32_WCE
  89       if ( !WriteFile(io_ptr, near_data, length, &check, NULL) )
  90          check = 0;
  91 #else
  92       check = fwrite(near_data, 1, length, io_ptr);
  93 #endif
  94    }
  95    else
  96    {
  97       png_byte buf[NEAR_BUF_SIZE];
  98       png_size_t written, remaining, err;
  99       check = 0;
 100       remaining = length;
 101       do
 102       {
 103          written = MIN(NEAR_BUF_SIZE, remaining);
 104          png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
 105 #ifdef _WIN32_WCE
 106          if ( !WriteFile(io_ptr, buf, written, &err, NULL) )
 107             err = 0;
 108 #else
 109          err = fwrite(buf, 1, written, io_ptr);
 110 #endif
 111          if (err != written)
 112             break;
 113
 114          else
 115             check += err;
 116
 117          data += written;
 118          remaining -= written;
 119       }
 120       while (remaining != 0);
 121    }
 122    if (check != length)
 123       png_error(png_ptr, "Write Error");
 124 }
 125
 126 #endif
 127 #endif
 128
 129 /* This function is called to output any data pending writing (normally
 130  * to disk).  After png_flush is called, there should be no data pending
 131  * writing in any buffers.
 132  */
 133 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 134 void /* PRIVATE */
 135 png_flush(png_structp png_ptr)
 136 {
 137    if (png_ptr->output_flush_fn != NULL)
 138       (*(png_ptr->output_flush_fn))(png_ptr);
 139 }
 140
 141 #ifdef PNG_STDIO_SUPPORTED
 142 void PNGAPI
 143 png_default_flush(png_structp png_ptr)
 144 {
 145 #ifndef _WIN32_WCE
 146    png_FILE_p io_ptr;
 147 #endif
 148    if (png_ptr == NULL)
 149       return;
 150 #ifndef _WIN32_WCE
 151    io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));
 152    fflush(io_ptr);
 153 #endif
 154 }
 155 #endif
 156 #endif
 157
 158 /* This function allows the application to supply new output functions for
 159  * libpng if standard C streams aren't being used.
 160  *
 161  * This function takes as its arguments:
 162  * png_ptr       - pointer to a png output data structure
 163  * io_ptr        - pointer to user supplied structure containing info about
 164  *                 the output functions.  May be NULL.
 165  * write_data_fn - pointer to a new output function that takes as its
 166  *                 arguments a pointer to a png_struct, a pointer to
 167  *                 data to be written, and a 32-bit unsigned int that is
 168  *                 the number of bytes to be written.  The new write
 169  *                 function should call png_error(png_ptr, "Error msg")
 170  *                 to exit and output any fatal error messages.  May be
 171  *                 NULL, in which case libpng's default function will
 172  *                 be used.
 173  * flush_data_fn - pointer to a new flush function that takes as its
 174  *                 arguments a pointer to a png_struct.  After a call to
 175  *                 the flush function, there should be no data in any buffers
 176  *                 or pending transmission.  If the output method doesn't do
 177  *                 any buffering of output, a function prototype must still be
 178  *                 supplied although it doesn't have to do anything.  If
 179  *                 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
 180  *                 time, output_flush_fn will be ignored, although it must be
 181  *                 supplied for compatibility.  May be NULL, in which case
 182  *                 libpng's default function will be used, if
 183  *                 PNG_WRITE_FLUSH_SUPPORTED is defined.  This is not
 184  *                 a good idea if io_ptr does not point to a standard
 185  *                 *FILE structure.
 186  */
 187 void PNGAPI
 188 png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
 189    png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
 190 {
 191    if (png_ptr == NULL)
 192       return;
 193
 194    png_ptr->io_ptr = io_ptr;
 195
 196 #ifdef PNG_STDIO_SUPPORTED
 197    if (write_data_fn != NULL)
 198       png_ptr->write_data_fn = write_data_fn;
 199
 200    else
 201       png_ptr->write_data_fn = png_default_write_data;
 202 #else
 203    png_ptr->write_data_fn = write_data_fn;
 204 #endif
 205
 206 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 207 #ifdef PNG_STDIO_SUPPORTED
 208    if (output_flush_fn != NULL)
 209       png_ptr->output_flush_fn = output_flush_fn;
 210
 211    else
 212       png_ptr->output_flush_fn = png_default_flush;
 213 #else
 214    png_ptr->output_flush_fn = output_flush_fn;
 215 #endif
 216 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
 217
 218    /* It is an error to read while writing a png file */
 219    if (png_ptr->read_data_fn != NULL)
 220    {
 221       png_ptr->read_data_fn = NULL;
 222       png_warning(png_ptr,
 223          "Attempted to set both read_data_fn and write_data_fn in");
 224       png_warning(png_ptr,
 225          "the same structure.  Resetting read_data_fn to NULL.");
 226    }
 227 }
 228
 229 #ifdef USE_FAR_KEYWORD
 230 #ifdef _MSC_VER
 231 void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
 232 {
 233    void *near_ptr;
 234    void FAR *far_ptr;
 235    FP_OFF(near_ptr) = FP_OFF(ptr);
 236    far_ptr = (void FAR *)near_ptr;
 237
 238    if (check != 0)
 239       if (FP_SEG(ptr) != FP_SEG(far_ptr))
 240          png_error(png_ptr, "segment lost in conversion");
 241
 242    return(near_ptr);
 243 }
 244 #  else
 245 void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
 246 {
 247    void *near_ptr;
 248    void FAR *far_ptr;
 249    near_ptr = (void FAR *)ptr;
 250    far_ptr = (void FAR *)near_ptr;
 251
 252    if (check != 0)
 253       if (far_ptr != ptr)
 254          png_error(png_ptr, "segment lost in conversion");
 255
 256    return(near_ptr);
 257 }
 258 #   endif
 259 #   endif
 260 #endif /* PNG_WRITE_SUPPORTED */