cosmopolitan/libc/stdio/fwritebuf.c

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2020-06-15 14:18:57 +00:00
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
vi: set net ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/nt/files.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/internal.h"
#include "libc/stdio/stdio.h"
/**
* One-shot writes data from stream buffer to underlying file or device.
*
* @param f is a non-null open stream handle
* @return number of bytes written or -1 on error
*/
int fwritebuf(FILE *f) {
ssize_t put;
unsigned bytes;
bytes = (f->beg < f->end ? f->end : f->size) - f->beg;
if ((put = write(f->fd, &f->buf[f->beg], bytes)) == -1) {
return (int)fseterrno(f);
}
f->beg = (unsigned)((f->beg + put) & (f->size - 1));
return bytes;
}