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 * @(#)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 * $DragonFly: src/lib/libc/stdio/fflush.c,v 1.6 2005/07/23 20:23:05 joerg Exp $ 35 */ 36 37 #include "namespace.h" 38 #include <errno.h> 39 #include <stdio.h> 40 #include "un-namespace.h" 41 #include "libc_private.h" 42 43 #include "local.h" 44 #include "priv_stdio.h" 45 46 static int sflush_locked(FILE *); 47 48 /* 49 * Flush a single file, or (if fp is NULL) all files. 50 * MT-safe version 51 */ 52 int 53 fflush(FILE *fp) 54 { 55 int retval; 56 57 if (fp == NULL) 58 return (_fwalk(sflush_locked)); 59 FLOCKFILE(fp); 60 61 /* 62 * There is disagreement about the correct behaviour of fflush() 63 * when passed a file which is not open for reading. According to 64 * the ISO C standard, the behaviour is undefined. 65 * Under linux, such an fflush returns success and has no effect; 66 * under Windows, such an fflush is documented as behaving instead 67 * as fpurge(). 68 * Given that applications may be written with the expectation of 69 * either of these two behaviours, the only safe (non-astonishing) 70 * option is to return EBADF and ask that applications be fixed. 71 */ 72 if ((fp->pub._flags & (__SWR | __SRW)) == 0) { 73 errno = EBADF; 74 retval = EOF; 75 } else { 76 retval = __sflush(fp); 77 } 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->pub._flags & (__SWR | __SRW)) == 0) { 94 errno = EBADF; 95 retval = EOF; 96 } else { 97 retval = __sflush(fp); 98 } 99 return (retval); 100 } 101 102 int 103 __sflush(FILE *fp) 104 { 105 unsigned char *p; 106 int n, t; 107 108 t = fp->pub._flags; 109 if ((t & __SWR) == 0) 110 return (0); 111 112 if ((p = fp->_bf._base) == NULL) 113 return (0); 114 115 n = fp->pub._p - p; /* write this much */ 116 117 /* 118 * Set these immediately to avoid problems with longjmp and to allow 119 * exchange buffering (via setvbuf) in user write function. 120 */ 121 fp->pub._p = p; 122 fp->pub._w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size; 123 124 for (; n > 0; n -= t, p += t) { 125 t = _swrite(fp, (char *)p, n); 126 if (t <= 0) { 127 fp->pub._flags |= __SERR; 128 return (EOF); 129 } 130 } 131 return (0); 132 } 133 134 static int 135 sflush_locked(FILE *fp) 136 { 137 int ret; 138 139 FLOCKFILE(fp); 140 ret = __sflush(fp); 141 FUNLOCKFILE(fp); 142 return (ret); 143 } 144