cosmopolitan/libc/stdio/fwritebuf.c

46 lines
2.6 KiB
C

/*-*- 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) {
if (errno == EINTR) return 0;
return (int)fseterrno(f);
}
f->beg = (unsigned)((f->beg + put) & (f->size - 1));
return bytes;
}