stdio/fflush-fbsd.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  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)fflush.c    8.1 (Berkeley) 6/4/93";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/stdio/fflush.c,v 1.13 2004/07/04 20:17:00 cperciva Exp $");
  42
  43 #include "namespace.h"
  44 #include <errno.h>
  45 #include <stdio.h>
  46 #include <string.h>
  47 #include "un-namespace.h"
  48 #include "libc_private.h"
  49 #include "local.h"
  50
  51 static int      sflush_locked(FILE *);
  52
  53 /*
  54  * Flush a single file, or (if fp is NULL) all files.
  55  * MT-safe version
  56  */
  57 int
  58 fflush(FILE *fp)
  59 {
  60         int retval;
  61
  62         if (fp == NULL)
  63                 return (_fwalk(sflush_locked));
  64         FLOCKFILE(fp);
  65
  66         /*
  67          * There is disagreement about the correct behaviour of fflush()
  68          * when passed a file which is not open for reading.  According to
  69          * the ISO C standard, the behaviour is undefined.
  70          * Under linux, such an fflush returns success and has no effect;
  71          * under Windows, such an fflush is documented as behaving instead
  72          * as fpurge().
  73          * Given that applications may be written with the expectation of
  74          * either of these two behaviours, the only safe (non-astonishing)
  75          * option is to return EBADF and ask that applications be fixed.
  76          */
  77         if ((fp->_flags & (__SWR | __SRW)) == 0) {
  78                 errno = EBADF;
  79                 retval = EOF;
  80         } else
  81                 retval = __sflush(fp);
  82         FUNLOCKFILE(fp);
  83         return (retval);
  84 }
  85
  86 /*
  87  * Flush a single file, or (if fp is NULL) all files.
  88  * Non-MT-safe version
  89  */
  90 int
  91 __fflush(FILE *fp)
  92 {
  93         int retval;
  94
  95         if (fp == NULL)
  96                 return (_fwalk(sflush_locked));
  97         if ((fp->_flags & (__SWR | __SRW)) == 0) {
  98                 errno = EBADF;
  99                 retval = EOF;
 100         } else
 101                 retval = __sflush(fp);
 102         return (retval);
 103 }
 104
 105 int
 106 __sflush(FILE *fp)
 107 {
 108         unsigned char *p;
 109         int n, t;
 110
 111         t = fp->_flags;
 112         if ((t & __SWR) == 0)
 113                 return (0);
 114
 115         if ((p = fp->_bf._base) == NULL)
 116                 return (0);
 117
 118         n = fp->_p - p;         /* write this much */
 119
 120         /*
 121          * Set these immediately to avoid problems with longjmp and to allow
 122          * exchange buffering (via setvbuf) in user write function.
 123          */
 124         fp->_p = p;
 125         fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
 126
 127         for (; n > 0; n -= t, p += t) {
 128                 t = _swrite(fp, (char *)p, n);
 129                 if (t <= 0) {
 130                         /* 5340694: reset _p and _w on EAGAIN */
 131                         if (t < 0 && errno == EAGAIN) {
 132                                 if (p > fp->_p) /* some was written */
 133                                         memmove(fp->_p, p, n);
 134                                 fp->_p += n;
 135                                 if (!(fp->_flags & (__SLBF|__SNBF)))
 136                                         fp->_w -= n;
 137                         }
 138                         fp->_flags |= __SERR;
 139                         return (EOF);
 140                 }
 141         }
 142         return (0);
 143 }
 144
 145 static int
 146 sflush_locked(FILE *fp)
 147 {
 148         int     ret;
 149
 150         FLOCKFILE(fp);
 151         ret = __sflush(fp);
 152         FUNLOCKFILE(fp);
 153         return (ret);
 154 }