lib/libc/stdio/fflush.c

   1 /*      $NetBSD: fflush.c,v 1.18 2012/03/27 15:05:42 christos Exp $     */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)fflush.c    8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: fflush.c,v 1.18 2012/03/27 15:05:42 christos Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include <stddef.h>
  45 #include <assert.h>
  46 #include <errno.h>
  47 #include <stdio.h>
  48 #include "reentrant.h"
  49 #include "local.h"
  50
  51 #ifdef _REENTRANT
  52 extern rwlock_t __sfp_lock;
  53 #endif
  54
  55 /* Flush a single file, or (if fp is NULL) all files.  */
  56 int
  57 fflush(FILE *fp)
  58 {
  59         int r;
  60
  61         if (fp == NULL) {
  62                 rwlock_rdlock(&__sfp_lock);
  63                 r = _fwalk(__sflush);
  64                 rwlock_unlock(&__sfp_lock);
  65                 return r;
  66         }
  67
  68         FLOCKFILE(fp);
  69         if ((fp->_flags & (__SWR | __SRW)) == 0) {
  70                 errno = EBADF;
  71                 r = EOF;
  72         } else {
  73                 r = __sflush(fp);
  74         }
  75         FUNLOCKFILE(fp);
  76         return r;
  77 }
  78
  79 int
  80 __sflush(FILE *fp)
  81 {
  82         unsigned char *p;
  83         size_t n;
  84         ssize_t t;
  85
  86         _DIAGASSERT(fp != NULL);
  87
  88         t = fp->_flags;
  89         if ((t & __SWR) == 0)
  90                 return 0;
  91
  92         if ((p = fp->_bf._base) == NULL)
  93                 return 0;
  94
  95         ptrdiff_t tp = fp->_p - p;
  96         _DIAGASSERT(__type_fit(ssize_t, tp));
  97         n = (ssize_t)tp;        /* write this much */
  98
  99         /*
 100          * Set these immediately to avoid problems with longjmp and to allow
 101          * exchange buffering (via setvbuf) in user write function.
 102          */
 103         fp->_p = p;
 104         fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
 105
 106         for (; n > 0; n -= t, p += t) {
 107                 t = (*fp->_write)(fp->_cookie, (char *)p, n);
 108                 if (t <= 0) {
 109                         fp->_flags |= __SERR;
 110                         return EOF;
 111                 }
 112         }
 113         if (fp->_flush)
 114                 return (*fp->_flush)(fp->_cookie);
 115         return 0;
 116 }