1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include "namespace.h" 36 #include <errno.h> 37 #include <stdio.h> 38 #include "un-namespace.h" 39 #include "libc_private.h" 40 #include "local.h" 41 42 static int sflush_locked(FILE *); 43 44 /* 45 * Flush a single file, or (if fp is NULL) all files. 46 * MT-safe version 47 */ 48 int 49 fflush(FILE *fp) 50 { 51 int retval; 52 53 if (fp == NULL) 54 return (_fwalk(sflush_locked)); 55 FLOCKFILE_CANCELSAFE(fp); 56 57 /* 58 * There is disagreement about the correct behaviour of fflush() 59 * when passed a file which is not open for writing. According to 60 * the ISO C standard, the behaviour is undefined. 61 * Under linux, such an fflush returns success and has no effect; 62 * under Windows, such an fflush is documented as behaving instead 63 * as fpurge(). 64 * Given that applications may be written with the expectation of 65 * either of these two behaviours, the only safe (non-astonishing) 66 * option is to return EBADF and ask that applications be fixed. 67 * SUSv3 now requires that fflush() returns success on a read-only 68 * stream. 69 * 70 */ 71 if ((fp->_flags & (__SWR | __SRW)) == 0) 72 retval = 0; 73 else 74 retval = __sflush(fp); 75 FUNLOCKFILE_CANCELSAFE(); 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->_flags & (__SWR | __SRW)) == 0) 91 retval = 0; 92 else 93 retval = __sflush(fp); 94 return (retval); 95 } 96 97 __weak_reference(__fflush, fflush_unlocked); 98 99 int 100 __sflush(FILE *fp) 101 { 102 unsigned char *p; 103 int n, f, t; 104 105 f = fp->_flags; 106 if ((f & __SWR) == 0) 107 return (0); 108 109 if ((p = fp->_bf._base) == NULL) 110 return (0); 111 112 n = fp->_p - p; /* write this much */ 113 114 /* 115 * Set these immediately to avoid problems with longjmp and to allow 116 * exchange buffering (via setvbuf) in user write function. 117 */ 118 fp->_p = p; 119 fp->_w = f & (__SLBF|__SNBF) ? 0 : fp->_bf._size; 120 121 for (; n > 0; n -= t, p += t) { 122 t = _swrite(fp, (char *)p, n); 123 if (t <= 0) { 124 if (p > fp->_p) 125 /* Some was written. */ 126 memmove(fp->_p, p, n); 127 /* Reset _p and _w. */ 128 fp->_p += n; 129 if ((fp->_flags & __SNBF) == 0) 130 fp->_w -= n; 131 fp->_flags |= __SERR; 132 return (EOF); 133 } 134 } 135 return (0); 136 } 137 138 static int 139 sflush_locked(FILE *fp) 140 { 141 int ret; 142 143 FLOCKFILE_CANCELSAFE(fp); 144 ret = __sflush(fp); 145 FUNLOCKFILE_CANCELSAFE(); 146 return (ret); 147 } 148