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sortix--sortix/libc/stdio/fflush_stop_reading.cpp
2013-12-17 14:30:39 +01:00

58 lines
1.9 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 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/>.
stdio/fflush_stop_reading.cpp
Resets the FILE to a consistent state so it is ready for writing.
*******************************************************************************/
#include <sys/types.h>
#include <assert.h>
#include <stdio.h>
extern "C" int fflush_stop_reading(FILE* fp)
{
if ( !(fp->flags & _FILE_LAST_READ) )
return 0;
int ret = 0;
size_t bufferahead = fp->amount_input_buffered - fp->offset_input_buffer;
if ( (fp->flags & _FILE_STREAM) )
{
if ( bufferahead )
/* TODO: Data loss!*/{}
}
if ( !(fp->flags & _FILE_STREAM) )
{
off_t rewind_amount = -((off_t) bufferahead);
off_t my_pos = fp->tell_func(fp->user);
off_t expected_pos = my_pos + rewind_amount;
#if 1
if ( fp->seek_func && fp->seek_func(fp->user, expected_pos, SEEK_SET) != 0 )
#else
if ( fp->seek_func && fp->seek_func(fp->user, rewind_amount, SEEK_CUR) != 0 )
#endif
ret = EOF;
off_t newpos = fp->tell_func(fp->user);
assert(ret == EOF || expected_pos == newpos);
}
fp->amount_input_buffered = fp->offset_input_buffer = 0;
fp->flags &= ~_FILE_LAST_READ;
return ret;
}