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 */ 70 if ((fp->pub._flags & (__SWR | __SRW)) == 0) { 71 errno = EBADF; 72 retval = EOF; 73 } else { 74 retval = __sflush(fp); 75 } 76 FUNLOCKFILE(fp); 77 return (retval); 78 } 79 80 /* 81 * Flush a single file, or (if fp is NULL) all files. 82 * Non-MT-safe version 83 */ 84 int 85 __fflush(FILE *fp) 86 { 87 int retval; 88 89 if (fp == NULL) 90 return (_fwalk(sflush_locked)); 91 if ((fp->pub._flags & (__SWR | __SRW)) == 0) { 92 errno = EBADF; 93 retval = EOF; 94 } else { 95 retval = __sflush(fp); 96 } 97 return (retval); 98 } 99 100 int 101 __sflush(FILE *fp) 102 { 103 unsigned char *p; 104 int n, t; 105 106 t = fp->pub._flags; 107 if ((t & __SWR) == 0) 108 return (0); 109 110 if ((p = fp->_bf._base) == NULL) 111 return (0); 112 113 n = fp->pub._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->pub._p = p; 120 fp->pub._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->pub._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 } 142