/*	$NetBSD: fflush.c,v 1.18 2012/03/27 15:05:42 christos 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 <sys/cdefs.h>
#include <stddef.h>
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include "reentrant.h"
#include "local.h"

#ifdef _REENTRANT
extern rwlock_t __sfp_lock;
#endif

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

  if (fp == NULL) {
    rwlock_rdlock(&__sfp_lock);
    r = _fwalk(__sflush);
    rwlock_unlock(&__sfp_lock);
    return r;
  }

  FLOCKFILE(fp);
  if ((fp->_flags & (__SWR | __SRW)) == 0) {
    errno = EBADF;
    r = EOF;
  } else {
    r = __sflush(fp);
  }
  FUNLOCKFILE(fp);
  return r;
}

int __sflush(FILE *fp) {
  unsigned char *p;
  size_t n;
  ssize_t t;

  _DIAGASSERT(fp != NULL);

  t = fp->_flags;
  if ((t & __SWR) == 0)
    return 0;

  if ((p = fp->_bf._base) == NULL)
    return 0;

  ptrdiff_t tp = fp->_p - p;
  _DIAGASSERT(__type_fit(ssize_t, tp));
  n = (ssize_t)tp; /* 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;
    }
  }
  if (fp->_flush)
    return (*fp->_flush)(fp->_cookie);
  return 0;
}
