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sortix--sortix/libc/fgetc.cpp
Jonas 'Sortie' Termansen 9ad7690c74 Rewrite stdio functions.
These changes aim to make the stdio functions much more stable, flexible,
correct and bugfree.
2013-12-17 14:30:26 +01:00

69 lines
2 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix C Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
fgetc.cpp
Reads a single character from a FILE.
*******************************************************************************/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
extern "C" int fgetc(FILE* fp)
{
if ( fp->flags & _FILE_NO_BUFFER )
{
unsigned char c;
if ( fread(&c, sizeof(c), 1, fp) != 1 )
return EOF;
return c;
}
if ( !fp->read_func )
return EOF; // TODO: ferror doesn't report error!
if ( fp->flags & _FILE_LAST_WRITE )
fflush_stop_writing(fp);
fp->flags |= _FILE_LAST_READ;
if ( fp->offset_input_buffer < fp->amount_input_buffered )
retry:
return fp->buffer[fp->offset_input_buffer++];
assert(fp->buffer && fp->buffersize);
size_t pushback = _FILE_MAX_PUSHBACK;
if ( fp->buffersize <= pushback )
pushback = 0;
size_t count = fp->buffersize - pushback;
size_t size = sizeof(unsigned char);
size_t numread = fp->read_func(fp->buffer + pushback, size, count, fp->user);
if ( !numread )
return EOF;
fp->offset_input_buffer = pushback;
fp->amount_input_buffered = pushback + numread;
goto retry;
}