/*      $OpenBSD: fflush.c,v 1.13 2025/08/08 15:58:53 yasuoka Exp $ */
/*-
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include "local.h"

/* Flush a single file, or (if fp is NULL) all files.  */
int
fflush(FILE *fp)
{
        int     r;

        if (fp == NULL)
                return (_fwalk(__sflush_locked));
        FLOCKFILE(fp);
        r = __sflush(fp);
        FUNLOCKFILE(fp);
        return (r);
}
DEF_STRONG(fflush);

int
__sflush(FILE *fp)
{
        unsigned char *p;
        fpos_t off;
        int n, t;

        t = fp->_flags;
        if (t & __SWR) {
                if ((p = fp->_bf._base) == NULL)
                        return (0);

                n = fp->_p - p;         /* write this much */

                /*
                 * Set these immediately to avoid problems with longjmp and to
                 * allow exchange buffering (via setvbuf) in user write
                 * function.
                 */
                fp->_p = p;
                fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;

                for (; n > 0; n -= t, p += t) {
                        t = (*fp->_write)(fp->_cookie, (char *)p, n);
                        if (t <= 0) {
                                fp->_flags |= __SERR;
                                return (EOF);
                        }
                }
        } else if ((t & __SRD) && !(t & __SEOF)) {
                if (fp->_seek != __sseek || fp->_file < 0) {
                        errno = EBADF;
                        return EOF;
                }

                off = fp->_r;
                if (HASUB(fp)) {
                        off = fp->_ur;
                        FREEUB(fp);
                }
                fp->_ungetwc_inbuf = 0;

                if (t & __SOFF) {
                        off = fp->_offset - off;
                        __sseek(fp->_cookie, off, SEEK_SET);
                } else if (off != 0)
                        __sseek(fp->_cookie, -off, SEEK_CUR);

                if ((fp->_flags & __SOFF)) {
                        fp->_p = fp->_bf._base;
                        fp->_r = 0;
                }
        }
        return (0);
}

int
__sflush_locked(FILE *fp)
{
        int     r;

        FLOCKFILE(fp);
        r = __sflush(fp);
        FUNLOCKFILE(fp);
        return (r);
}