The Tor Browser / file revision

 /* pngwio.c - functions for data output

  *

  * Last changed in libpng 1.6.9 [February 6, 2014]

  * Copyright (c) 1998-2014 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.)

  *

  * This code is released under the libpng license.

  * For conditions of distribution and use, see the disclaimer

  * and license in png.h

  *

  * This file provides a location for all output.  Users who need

  * special handling are expected to write functions that have the same

  * arguments as these and perform similar functions, but that possibly

  * use different output methods.  Note that you shouldn't change these

  * functions, but rather write replacement functions and then change

  * them at run time with png_set_write_fn(...).

  */

 #include "pngpriv.h"

 #ifdef PNG_WRITE_SUPPORTED

 /* Write the data to whatever output you are using.  The default routine

  * writes to a file pointer.  Note that this routine sometimes gets called

  * with very small lengths, so you should implement some kind of simple

  * buffering if you are using unbuffered writes.  This should never be asked

  * to write more than 64K on a 16 bit machine.

  */

 void /* PRIVATE */

 png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)

 {

    /* NOTE: write_data_fn must not change the buffer! */

    if (png_ptr->write_data_fn != NULL )

       (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),

          length);

    else

       png_error(png_ptr, "Call to NULL write function");

 }

 #ifdef PNG_STDIO_SUPPORTED

 /* This is the function that does the actual writing of data.  If you are

  * not writing to a standard C stream, you should create a replacement

  * write_data function and use it at run time with png_set_write_fn(), rather

  * than changing the library.

  */

 void PNGCBAPI

 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)

 {

    png_size_t check;

    if (png_ptr == NULL)

       return;

    check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));

    if (check != length)

       png_error(png_ptr, "Write Error");

 }

 #endif

 /* This function is called to output any data pending writing (normally

  * to disk).  After png_flush is called, there should be no data pending

  * writing in any buffers.

  */

 #ifdef PNG_WRITE_FLUSH_SUPPORTED

 void /* PRIVATE */

 png_flush(png_structrp png_ptr)

 {

    if (png_ptr->output_flush_fn != NULL)

       (*(png_ptr->output_flush_fn))(png_ptr);

 }

 #  ifdef PNG_STDIO_SUPPORTED

 void PNGCBAPI

 png_default_flush(png_structp png_ptr)

 {

    png_FILE_p io_ptr;

    if (png_ptr == NULL)

       return;

    io_ptr = png_voidcast(png_FILE_p, (png_ptr->io_ptr));

    fflush(io_ptr);

 }

 #  endif

 #endif

 /* This function allows the application to supply new output functions for

  * libpng if standard C streams aren't being used.

  *

  * This function takes as its arguments:

  * png_ptr       - pointer to a png output data structure

  * io_ptr        - pointer to user supplied structure containing info about

  *                 the output functions.  May be NULL.

  * write_data_fn - pointer to a new output function that takes as its

  *                 arguments a pointer to a png_struct, a pointer to

  *                 data to be written, and a 32-bit unsigned int that is

  *                 the number of bytes to be written.  The new write

  *                 function should call png_error(png_ptr, "Error msg")

  *                 to exit and output any fatal error messages.  May be

  *                 NULL, in which case libpng's default function will

  *                 be used.

  * flush_data_fn - pointer to a new flush function that takes as its

  *                 arguments a pointer to a png_struct.  After a call to

  *                 the flush function, there should be no data in any buffers

  *                 or pending transmission.  If the output method doesn't do

  *                 any buffering of output, a function prototype must still be

  *                 supplied although it doesn't have to do anything.  If

  *                 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile

  *                 time, output_flush_fn will be ignored, although it must be

  *                 supplied for compatibility.  May be NULL, in which case

  *                 libpng's default function will be used, if

  *                 PNG_WRITE_FLUSH_SUPPORTED is defined.  This is not

  *                 a good idea if io_ptr does not point to a standard

  *                 *FILE structure.

  */

 void PNGAPI

 png_set_write_fn(png_structrp png_ptr, png_voidp io_ptr,

     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)

 {

    if (png_ptr == NULL)

       return;

    png_ptr->io_ptr = io_ptr;

 #ifdef PNG_STDIO_SUPPORTED

    if (write_data_fn != NULL)

       png_ptr->write_data_fn = write_data_fn;

    else

       png_ptr->write_data_fn = png_default_write_data;

 #else

    png_ptr->write_data_fn = write_data_fn;

 #endif

 #ifdef PNG_WRITE_FLUSH_SUPPORTED

 #  ifdef PNG_STDIO_SUPPORTED

    if (output_flush_fn != NULL)

       png_ptr->output_flush_fn = output_flush_fn;

    else

       png_ptr->output_flush_fn = png_default_flush;

 #  else

    png_ptr->output_flush_fn = output_flush_fn;

 #  endif

 #else

    PNG_UNUSED(output_flush_fn)

 #endif /* PNG_WRITE_FLUSH_SUPPORTED */

 #ifdef PNG_READ_SUPPORTED

    /* It is an error to read while writing a png file */

    if (png_ptr->read_data_fn != NULL)

    {

       png_ptr->read_data_fn = NULL;

       png_warning(png_ptr,

           "Can't set both read_data_fn and write_data_fn in the"

           " same structure");

    }

 #endif

 }

 #endif /* PNG_WRITE_SUPPORTED */