stdio/FreeBSD/fflush.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)fflush.c    8.1 (Berkeley) 6/4/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdio/fflush.c,v 1.14 2007/01/09 00:28:06 imp Exp $");
  38
  39 #include "namespace.h"
  40 #include <errno.h>
  41 #include <stdio.h>
  42 #include "un-namespace.h"
  43 #include "libc_private.h"
  44 #include "local.h"
  45
  46 static int      sflush_locked(FILE *);
  47
  48 /*
  49  * Flush a single file, or (if fp is NULL) all files.
  50  * MT-safe version
  51  */
  52 int
  53 fflush(FILE *fp)
  54 {
  55         int retval;
  56
  57         if (fp == NULL)
  58                 return (_fwalk(sflush_locked));
  59         FLOCKFILE(fp);
  60
  61         /*
  62          * There is disagreement about the correct behaviour of fflush()
  63          * when passed a file which is not open for reading.  According to
  64          * the ISO C standard, the behaviour is undefined.
  65          * Under linux, such an fflush returns success and has no effect;
  66          * under Windows, such an fflush is documented as behaving instead
  67          * as fpurge().
  68          * Given that applications may be written with the expectation of
  69          * either of these two behaviours, the only safe (non-astonishing)
  70          * option is to return EBADF and ask that applications be fixed.
  71          */
  72         if ((fp->_flags & (__SWR | __SRW)) == 0) {
  73                 errno = EBADF;
  74                 retval = EOF;
  75         } else
  76                 retval = __sflush(fp);
  77         FUNLOCKFILE(fp);
  78         return (retval);
  79 }
  80
  81 /*
  82  * Flush a single file, or (if fp is NULL) all files.
  83  * Non-MT-safe version
  84  */
  85 int
  86 __fflush(FILE *fp)
  87 {
  88         int retval;
  89
  90         if (fp == NULL)
  91                 return (_fwalk(sflush_locked));
  92         if ((fp->_flags & (__SWR | __SRW)) == 0) {
  93                 errno = EBADF;
  94                 retval = EOF;
  95         } else
  96                 retval = __sflush(fp);
  97         return (retval);
  98 }
  99
 100 int
 101 __sflush(FILE *fp)
 102 {
 103         unsigned char *p;
 104         int n, t;
 105
 106         t = fp->_flags;
 107         if ((t & __SWR) == 0)
 108                 return (0);
 109
 110         if ((p = fp->_bf._base) == NULL)
 111                 return (0);
 112
 113         n = fp->_p - p;         /* write this much */
 114
 115         /*
 116          * Set these immediately to avoid problems with longjmp and to allow
 117          * exchange buffering (via setvbuf) in user write function.
 118          */
 119         fp->_p = p;
 120         fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
 121
 122         for (; n > 0; n -= t, p += t) {
 123                 t = _swrite(fp, (char *)p, n);
 124                 if (t <= 0) {
 125                         fp->_flags |= __SERR;
 126                         return (EOF);
 127                 }
 128         }
 129         return (0);
 130 }
 131
 132 static int
 133 sflush_locked(FILE *fp)
 134 {
 135         int     ret;
 136
 137         FLOCKFILE(fp);
 138         ret = __sflush(fp);
 139         FUNLOCKFILE(fp);
 140         return (ret);
 141 }