/* pngwio.c - functions for data output

*

* Last changed in libpng 1.5.0 [January 6, 2011]

* Copyright (c) 1998-2011 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_structp 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_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.

*/

#ifndef USE_FAR_KEYWORD

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");

}

#else

/* This is the model-independent version. Since the standard I/O library

* can't handle far buffers in the medium and small models, we have to copy

* the data.

*/

#define NEAR_BUF_SIZE 1024

#define MIN(a,b) (a <= b ? a : b)

void PNGCBAPI

png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)

{

png_uint_32 check;

png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */

png_FILE_p io_ptr;

if (png_ptr == NULL)

return;

/* Check if data really is near. If so, use usual code. */

near_data = (png_byte *)CVT_PTR_NOCHECK(data);

io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);

if ((png_bytep)near_data == data)

{

check = fwrite(near_data, 1, length, io_ptr);

}

else

{

png_byte buf[NEAR_BUF_SIZE];

png_size_t written, remaining, err;

check = 0;

remaining = length;

do

{

written = MIN(NEAR_BUF_SIZE, remaining);

png_memcpy(buf, data, written); /* Copy far buffer to near buffer */

err = fwrite(buf, 1, written, io_ptr);

if (err != written)

break;

else

check += err;

data += written;

remaining -= written;

}

while (remaining != 0);

}

if (check != length)

png_error(png_ptr, "Write Error");

}

#endif

#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_structp 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_FILE_p)CVT_PTR((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_structp 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

#endif /* PNG_WRITE_FLUSH_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");

}

}

#ifdef USE_FAR_KEYWORD

# ifdef _MSC_VER

void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)

{

void *near_ptr;

void FAR *far_ptr;

FP_OFF(near_ptr) = FP_OFF(ptr);

far_ptr = (void FAR *)near_ptr;

if (check != 0)

if (FP_SEG(ptr) != FP_SEG(far_ptr))

png_error(png_ptr, "segment lost in conversion");

return(near_ptr);

}

# else

void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)

{

void *near_ptr;

void FAR *far_ptr;

near_ptr = (void FAR *)ptr;

far_ptr = (void FAR *)near_ptr;

if (check != 0)

if (far_ptr != ptr)

png_error(png_ptr, "segment lost in conversion");

return(near_ptr);

}

# endif

#endif

#endif /* PNG_WRITE_SUPPORTED */