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  * 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 <string.h>
  43 #include "un-namespace.h"
  44 #include "libc_private.h"
  45 #include "local.h"
  46
  47 static int      sflush_locked(FILE *);
  48
  49 /*
  50  * Flush a single file, or (if fp is NULL) all files.
  51  * MT-safe version
  52  */
  53 int
  54 fflush(FILE *fp)
  55 {
  56         int retval;
  57
  58         if (fp == NULL)
  59                 return (_fwalk(sflush_locked));
  60         FLOCKFILE(fp);
  61
  62         /*
  63          * There is disagreement about the correct behaviour of fflush()
  64          * when passed a file which is not open for reading.  According to
  65          * the ISO C standard, the behaviour is undefined.
  66          * Under linux, such an fflush returns success and has no effect;
  67          * under Windows, such an fflush is documented as behaving instead
  68          * as fpurge().
  69          * Given that applications may be written with the expectation of
  70          * either of these two behaviours, the only safe (non-astonishing)
  71          * option is to return EBADF and ask that applications be fixed.
  72          */
  73         if ((fp->_flags & (__SWR | __SRW)) == 0) {
  74                 errno = EBADF;
  75                 retval = EOF;
  76         } else
  77                 retval = __sflush(fp);
  78         FUNLOCKFILE(fp);
  79         return (retval);
  80 }
  81
  82 /*
  83  * Flush a single file, or (if fp is NULL) all files.
  84  * Non-MT-safe version
  85  */
  86 int
  87 __fflush(FILE *fp)
  88 {
  89         int retval;
  90
  91         if (fp == NULL)
  92                 return (_fwalk(sflush_locked));
  93         if ((fp->_flags & (__SWR | __SRW)) == 0) {
  94                 errno = EBADF;
  95                 retval = EOF;
  96         } else
  97                 retval = __sflush(fp);
  98         return (retval);
  99 }
 100
 101 int
 102 __sflush(FILE *fp)
 103 {
 104         unsigned char *p;
 105         int n, t;
 106
 107         t = fp->_flags;
 108         if ((t & __SWR) == 0)
 109                 return (0);
 110
 111         if ((p = fp->_bf._base) == NULL)
 112                 return (0);
 113
 114         n = fp->_p - p;         /* write this much */
 115
 116         /*
 117          * Set these immediately to avoid problems with longjmp and to allow
 118          * exchange buffering (via setvbuf) in user write function.
 119          */
 120         fp->_p = p;
 121         fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
 122
 123         for (; n > 0; n -= t, p += t) {
 124                 t = _swrite(fp, (char *)p, n);
 125                 if (t <= 0) {
 126                         /* 5340694: reset _p and _w on EAGAIN */
 127                         if (t < 0 && errno == EAGAIN) {
 128                                 if (p > fp->_p) /* some was written */
 129                                         memmove(fp->_p, p, n);
 130                                 fp->_p += n;
 131                                 if (!(fp->_flags & (__SLBF|__SNBF)))
 132                                         fp->_w -= n;
 133                         }
 134                         fp->_flags |= __SERR;
 135                         return (EOF);
 136                 }
 137         }
 138         return (0);
 139 }
 140
 141 static int
 142 sflush_locked(FILE *fp)
 143 {
 144         int     ret;
 145
 146         FLOCKFILE(fp);
 147         ret = __sflush(fp);
 148         FUNLOCKFILE(fp);
 149         return (ret);
 150 }