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 <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 = 0;
  57
  58         if (fp == NULL) {
  59                 return (_fwalk(sflush_locked));
  60         }
  61
  62         FLOCKFILE(fp);
  63         retval = __sflush(fp);
  64         FUNLOCKFILE(fp);
  65         return (retval);
  66 }
  67
  68 /*
  69  * Flush a single file, or (if fp is NULL) all files.
  70  * Non-MT-safe version
  71  */
  72 int
  73 __fflush(FILE *fp)
  74 {
  75         int retval;
  76
  77         if (fp == NULL)
  78                 return (_fwalk(sflush_locked));
  79         if ((fp->_flags & (__SWR | __SRW)) == 0) {
  80                 retval = 0;
  81         } else
  82                 retval = __sflush(fp);
  83         return (retval);
  84 }
  85
  86 int
  87 __sflush(FILE *fp)
  88 {
  89         unsigned char *p;
  90         int n, t;
  91
  92         t = fp->_flags;
  93
  94         if ((p = fp->_bf._base) == NULL)
  95                 return (0);
  96
  97         /*
  98          * SUSv3 requires that fflush() on a seekable input stream updates the file
  99          * position indicator with the underlying seek function.  Use a dumb fseek
 100          * for this (don't attempt to preserve the buffers).
 101          */
 102         if ((t & __SRD) != 0) {
 103                 if (fp->_seek == NULL) {
 104                         /*
 105                          * No way to seek this file -- just return "success."
 106                          */
 107                         return (0);
 108                 }
 109
 110                 n = fp->_r;
 111
 112                 if (n > 0) {
 113                         /*
 114                          * See _fseeko's dumb path.
 115                          */
 116                         if (_sseek(fp, (fpos_t)-n, SEEK_CUR) == -1) {
 117                                 if (errno == ESPIPE) {
 118                                         /*
 119                                          * Ignore ESPIPE errors, since there's no way to put the bytes
 120                                          * back into the pipe.
 121                                          */
 122                                         return (0);
 123                                 }
 124                                 return (EOF);
 125                         }
 126
 127                         if (HASUB(fp)) {
 128                                 FREEUB(fp);
 129                         }
 130                         fp->_p = fp->_bf._base;
 131                         fp->_r = 0;
 132                         fp->_flags &= ~__SEOF;
 133                         memset(&fp->_mbstate, 0, sizeof(mbstate_t));
 134                 }
 135                 return (0);
 136         }
 137
 138         if ((t & __SWR) != 0) {
 139                 n = fp->_p - p;         /* write this much */
 140
 141                 /*
 142                  * Set these immediately to avoid problems with longjmp and to allow
 143                  * exchange buffering (via setvbuf) in user write function.
 144                  */
 145                 fp->_p = p;
 146                 fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
 147
 148                 for (; n > 0; n -= t, p += t) {
 149                         t = _swrite(fp, (char *)p, n);
 150                         if (t <= 0) {
 151                                 /* 5340694: reset _p and _w on EAGAIN */
 152                                 if (t < 0 && errno == EAGAIN) {
 153                                         if (p > fp->_p) {
 154                                                 /* some was written */
 155                                                 memmove(fp->_p, p, n);
 156                                                 fp->_p += n;
 157                                                 if (!(fp->_flags & (__SLBF|__SNBF)))
 158                                                         fp->_w -= n;
 159                                         }
 160                                 }
 161                                 fp->_flags |= __SERR;
 162                                 return (EOF);
 163                         }
 164                 }
 165         }
 166         return (0);
 167 }
 168
 169 static int
 170 sflush_locked(FILE *fp)
 171 {
 172         int     ret;
 173
 174         FLOCKFILE(fp);
 175         ret = __sflush(fp);
 176         FUNLOCKFILE(fp);
 177         return (ret);
 178 }