michael@0: 
michael@0: /* pngwio.c - functions for data output
michael@0:  *
michael@0:  * Last changed in libpng 1.6.9 [February 6, 2014]
michael@0:  * Copyright (c) 1998-2014 Glenn Randers-Pehrson
michael@0:  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
michael@0:  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
michael@0:  *
michael@0:  * This code is released under the libpng license.
michael@0:  * For conditions of distribution and use, see the disclaimer
michael@0:  * and license in png.h
michael@0:  *
michael@0:  * This file provides a location for all output.  Users who need
michael@0:  * special handling are expected to write functions that have the same
michael@0:  * arguments as these and perform similar functions, but that possibly
michael@0:  * use different output methods.  Note that you shouldn't change these
michael@0:  * functions, but rather write replacement functions and then change
michael@0:  * them at run time with png_set_write_fn(...).
michael@0:  */
michael@0: 
michael@0: #include "pngpriv.h"
michael@0: 
michael@0: #ifdef PNG_WRITE_SUPPORTED
michael@0: 
michael@0: /* Write the data to whatever output you are using.  The default routine
michael@0:  * writes to a file pointer.  Note that this routine sometimes gets called
michael@0:  * with very small lengths, so you should implement some kind of simple
michael@0:  * buffering if you are using unbuffered writes.  This should never be asked
michael@0:  * to write more than 64K on a 16 bit machine.
michael@0:  */
michael@0: 
michael@0: void /* PRIVATE */
michael@0: png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
michael@0: {
michael@0:    /* NOTE: write_data_fn must not change the buffer! */
michael@0:    if (png_ptr->write_data_fn != NULL )
michael@0:       (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),
michael@0:          length);
michael@0: 
michael@0:    else
michael@0:       png_error(png_ptr, "Call to NULL write function");
michael@0: }
michael@0: 
michael@0: #ifdef PNG_STDIO_SUPPORTED
michael@0: /* This is the function that does the actual writing of data.  If you are
michael@0:  * not writing to a standard C stream, you should create a replacement
michael@0:  * write_data function and use it at run time with png_set_write_fn(), rather
michael@0:  * than changing the library.
michael@0:  */
michael@0: void PNGCBAPI
michael@0: png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
michael@0: {
michael@0:    png_size_t check;
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
michael@0: 
michael@0:    if (check != length)
michael@0:       png_error(png_ptr, "Write Error");
michael@0: }
michael@0: #endif
michael@0: 
michael@0: /* This function is called to output any data pending writing (normally
michael@0:  * to disk).  After png_flush is called, there should be no data pending
michael@0:  * writing in any buffers.
michael@0:  */
michael@0: #ifdef PNG_WRITE_FLUSH_SUPPORTED
michael@0: void /* PRIVATE */
michael@0: png_flush(png_structrp png_ptr)
michael@0: {
michael@0:    if (png_ptr->output_flush_fn != NULL)
michael@0:       (*(png_ptr->output_flush_fn))(png_ptr);
michael@0: }
michael@0: 
michael@0: #  ifdef PNG_STDIO_SUPPORTED
michael@0: void PNGCBAPI
michael@0: png_default_flush(png_structp png_ptr)
michael@0: {
michael@0:    png_FILE_p io_ptr;
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    io_ptr = png_voidcast(png_FILE_p, (png_ptr->io_ptr));
michael@0:    fflush(io_ptr);
michael@0: }
michael@0: #  endif
michael@0: #endif
michael@0: 
michael@0: /* This function allows the application to supply new output functions for
michael@0:  * libpng if standard C streams aren't being used.
michael@0:  *
michael@0:  * This function takes as its arguments:
michael@0:  * png_ptr       - pointer to a png output data structure
michael@0:  * io_ptr        - pointer to user supplied structure containing info about
michael@0:  *                 the output functions.  May be NULL.
michael@0:  * write_data_fn - pointer to a new output function that takes as its
michael@0:  *                 arguments a pointer to a png_struct, a pointer to
michael@0:  *                 data to be written, and a 32-bit unsigned int that is
michael@0:  *                 the number of bytes to be written.  The new write
michael@0:  *                 function should call png_error(png_ptr, "Error msg")
michael@0:  *                 to exit and output any fatal error messages.  May be
michael@0:  *                 NULL, in which case libpng's default function will
michael@0:  *                 be used.
michael@0:  * flush_data_fn - pointer to a new flush function that takes as its
michael@0:  *                 arguments a pointer to a png_struct.  After a call to
michael@0:  *                 the flush function, there should be no data in any buffers
michael@0:  *                 or pending transmission.  If the output method doesn't do
michael@0:  *                 any buffering of output, a function prototype must still be
michael@0:  *                 supplied although it doesn't have to do anything.  If
michael@0:  *                 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
michael@0:  *                 time, output_flush_fn will be ignored, although it must be
michael@0:  *                 supplied for compatibility.  May be NULL, in which case
michael@0:  *                 libpng's default function will be used, if
michael@0:  *                 PNG_WRITE_FLUSH_SUPPORTED is defined.  This is not
michael@0:  *                 a good idea if io_ptr does not point to a standard
michael@0:  *                 *FILE structure.
michael@0:  */
michael@0: void PNGAPI
michael@0: png_set_write_fn(png_structrp png_ptr, png_voidp io_ptr,
michael@0:     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
michael@0: {
michael@0:    if (png_ptr == NULL)
michael@0:       return;
michael@0: 
michael@0:    png_ptr->io_ptr = io_ptr;
michael@0: 
michael@0: #ifdef PNG_STDIO_SUPPORTED
michael@0:    if (write_data_fn != NULL)
michael@0:       png_ptr->write_data_fn = write_data_fn;
michael@0: 
michael@0:    else
michael@0:       png_ptr->write_data_fn = png_default_write_data;
michael@0: #else
michael@0:    png_ptr->write_data_fn = write_data_fn;
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_WRITE_FLUSH_SUPPORTED
michael@0: #  ifdef PNG_STDIO_SUPPORTED
michael@0: 
michael@0:    if (output_flush_fn != NULL)
michael@0:       png_ptr->output_flush_fn = output_flush_fn;
michael@0: 
michael@0:    else
michael@0:       png_ptr->output_flush_fn = png_default_flush;
michael@0: 
michael@0: #  else
michael@0:    png_ptr->output_flush_fn = output_flush_fn;
michael@0: #  endif
michael@0: #else
michael@0:    PNG_UNUSED(output_flush_fn)
michael@0: #endif /* PNG_WRITE_FLUSH_SUPPORTED */
michael@0: 
michael@0: #ifdef PNG_READ_SUPPORTED
michael@0:    /* It is an error to read while writing a png file */
michael@0:    if (png_ptr->read_data_fn != NULL)
michael@0:    {
michael@0:       png_ptr->read_data_fn = NULL;
michael@0: 
michael@0:       png_warning(png_ptr,
michael@0:           "Can't set both read_data_fn and write_data_fn in the"
michael@0:           " same structure");
michael@0:    }
michael@0: #endif
michael@0: }
michael@0: #endif /* PNG_WRITE_SUPPORTED */