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. 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 * @(#)fflush.c 8.1 (Berkeley) 6/4/93 33 * $FreeBSD: src/lib/libc/stdio/fflush.c,v 1.14 2007/01/09 00:28:06 imp Exp $ 34 */ 35 36 #include "namespace.h" 37 #include <errno.h> 38 #include <stdio.h> 39 #include "un-namespace.h" 40 #include "libc_private.h" 41 42 #include "local.h" 43 44 static int sflush_locked(FILE *); 45 46 /* 47 * Flush a single file, or (if fp is NULL) all files. 48 * MT-safe version 49 */ 50 int 51 fflush(FILE *fp) 52 { 53 int retval; 54 55 if (fp == NULL) 56 return (_fwalk(sflush_locked)); 57 FLOCKFILE(fp); 58 59 /* 60 * There is disagreement about the correct behaviour of fflush() 61 * when passed a file which is not open for reading. According to 62 * the ISO C standard, the behaviour is undefined. 63 * Under linux, such an fflush returns success and has no effect; 64 * under Windows, such an fflush is documented as behaving instead 65 * as fpurge(). 66 * Given that applications may be written with the expectation of 67 * either of these two behaviours, the only safe (non-astonishing) 68 * option is to return EBADF and ask that applications be fixed. 69 * But for c++ compatibility do not enforce it and match FreeBSD. 70 */ 71 if ((fp->pub._flags & (__SWR | __SRW)) == 0) 72 retval = 0; 73 else 74 retval = __sflush(fp); 75 FUNLOCKFILE(fp); 76 return (retval); 77 } 78 79 /* 80 * Flush a single file, or (if fp is NULL) all files. 81 * Non-MT-safe version 82 */ 83 int 84 __fflush(FILE *fp) 85 { 86 int retval; 87 88 if (fp == NULL) 89 return (_fwalk(sflush_locked)); 90 if ((fp->pub._flags & (__SWR | __SRW)) == 0) 91 retval = 0; 92 else 93 retval = __sflush(fp); 94 return (retval); 95 } 96 97 int 98 __sflush(FILE *fp) 99 { 100 unsigned char *p; 101 int n, t; 102 103 t = fp->pub._flags; 104 if ((t & __SWR) == 0) 105 return (0); 106 107 if ((p = fp->_bf._base) == NULL) 108 return (0); 109 110 n = fp->pub._p - p; /* write this much */ 111 112 /* 113 * Set these immediately to avoid problems with longjmp and to allow 114 * exchange buffering (via setvbuf) in user write function. 115 */ 116 fp->pub._p = p; 117 fp->pub._w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size; 118 119 for (; n > 0; n -= t, p += t) { 120 t = _swrite(fp, (char *)p, n); 121 if (t <= 0) { 122 /* Reset _p and _w. */ 123 if (p > fp->pub._p) { 124 /* Some was written. */ 125 memmove(fp->pub._p, p, n); 126 fp->pub._p += n; 127 if ((fp->pub._flags & (__SLBF | __SNBF)) == 0) 128 fp->pub._w -= n; 129 } 130 fp->pub._flags |= __SERR; 131 return (EOF); 132 } 133 } 134 return (0); 135 } 136 137 static int 138 sflush_locked(FILE *fp) 139 { 140 int ret; 141 142 FLOCKFILE(fp); 143 ret = __sflush(fp); 144 FUNLOCKFILE(fp); 145 return (ret); 146 } 147