mirror of
https://git.do.srb2.org/STJr/SRB2.git
synced 2024-12-26 20:50:49 +00:00
120 lines
3.8 KiB
C
120 lines
3.8 KiB
C
|
|
/* pngrio.c - functions for data input
|
|
*
|
|
* Copyright (c) 2018 Cosmin Truta
|
|
* Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson
|
|
* Copyright (c) 1996-1997 Andreas Dilger
|
|
* 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 input. Users who need
|
|
* special handling are expected to write a function that has the same
|
|
* arguments as this and performs a similar function, but that possibly
|
|
* has a different input method. Note that you shouldn't change this
|
|
* function, but rather write a replacement function and then make
|
|
* libpng use it at run time with png_set_read_fn(...).
|
|
*/
|
|
|
|
#include "pngpriv.h"
|
|
|
|
#ifdef PNG_READ_SUPPORTED
|
|
|
|
/* Read the data from whatever input you are using. The default routine
|
|
* reads from 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 reads. This should never be asked
|
|
* to read more than 64K on a 16-bit machine.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_read_data(png_structrp png_ptr, png_bytep data, size_t length)
|
|
{
|
|
png_debug1(4, "reading %d bytes", (int)length);
|
|
|
|
if (png_ptr->read_data_fn != NULL)
|
|
(*(png_ptr->read_data_fn))(png_ptr, data, length);
|
|
|
|
else
|
|
png_error(png_ptr, "Call to NULL read function");
|
|
}
|
|
|
|
#ifdef PNG_STDIO_SUPPORTED
|
|
/* This is the function that does the actual reading of data. If you are
|
|
* not reading from a standard C stream, you should create a replacement
|
|
* read_data function and use it at run time with png_set_read_fn(), rather
|
|
* than changing the library.
|
|
*/
|
|
void PNGCBAPI
|
|
png_default_read_data(png_structp png_ptr, png_bytep data, size_t length)
|
|
{
|
|
size_t check;
|
|
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
/* fread() returns 0 on error, so it is OK to store this in a size_t
|
|
* instead of an int, which is what fread() actually returns.
|
|
*/
|
|
check = fread(data, 1, length, png_voidcast(png_FILE_p, png_ptr->io_ptr));
|
|
|
|
if (check != length)
|
|
png_error(png_ptr, "Read Error");
|
|
}
|
|
#endif
|
|
|
|
/* This function allows the application to supply a new input function
|
|
* for libpng if standard C streams aren't being used.
|
|
*
|
|
* This function takes as its arguments:
|
|
*
|
|
* png_ptr - pointer to a png input data structure
|
|
*
|
|
* io_ptr - pointer to user supplied structure containing info about
|
|
* the input functions. May be NULL.
|
|
*
|
|
* read_data_fn - pointer to a new input function that takes as its
|
|
* arguments a pointer to a png_struct, a pointer to
|
|
* a location where input data can be stored, and a 32-bit
|
|
* unsigned int that is the number of bytes to be read.
|
|
* To exit and output any fatal error messages the new write
|
|
* function should call png_error(png_ptr, "Error msg").
|
|
* May be NULL, in which case libpng's default function will
|
|
* be used.
|
|
*/
|
|
void PNGAPI
|
|
png_set_read_fn(png_structrp png_ptr, png_voidp io_ptr,
|
|
png_rw_ptr read_data_fn)
|
|
{
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
png_ptr->io_ptr = io_ptr;
|
|
|
|
#ifdef PNG_STDIO_SUPPORTED
|
|
if (read_data_fn != NULL)
|
|
png_ptr->read_data_fn = read_data_fn;
|
|
|
|
else
|
|
png_ptr->read_data_fn = png_default_read_data;
|
|
#else
|
|
png_ptr->read_data_fn = read_data_fn;
|
|
#endif
|
|
|
|
#ifdef PNG_WRITE_SUPPORTED
|
|
/* It is an error to write to a read device */
|
|
if (png_ptr->write_data_fn != NULL)
|
|
{
|
|
png_ptr->write_data_fn = NULL;
|
|
png_warning(png_ptr,
|
|
"Can't set both read_data_fn and write_data_fn in the"
|
|
" same structure");
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_WRITE_FLUSH_SUPPORTED
|
|
png_ptr->output_flush_fn = NULL;
|
|
#endif
|
|
}
|
|
#endif /* READ */
|