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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)freopen.c 8.1 (Berkeley) 6/4/93 37 * $FreeBSD: src/lib/libc/stdio/freopen.c,v 1.5.2.1 2001/03/05 10:54:53 obrien Exp $ 38 * $DragonFly: src/lib/libc/stdio/freopen.c,v 1.6 2005/07/23 20:23:06 joerg Exp $ 39 */ 40 41 #include "namespace.h" 42 #include <sys/types.h> 43 #include <sys/stat.h> 44 #include <fcntl.h> 45 #include <errno.h> 46 #include <unistd.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include "un-namespace.h" 50 51 #include "libc_private.h" 52 #include "local.h" 53 #include "priv_stdio.h" 54 55 /* 56 * Re-direct an existing, open (probably) file to some other file. 57 * ANSI is written such that the original file gets closed if at 58 * all possible, no matter what. 59 */ 60 FILE * 61 freopen(const char *file, const char *mode, FILE *fp) 62 { 63 int f; 64 int dflags, flags, isopen, oflags, sverrno, wantfd; 65 66 if ((flags = __sflags(mode, &oflags)) == 0) { 67 (void) fclose(fp); 68 return (NULL); 69 } 70 71 FLOCKFILE(fp); 72 73 if (!__sdidinit) 74 __sinit(); 75 76 sverrno = 0; 77 78 /* 79 * If the filename is a NULL pointer, the caller is asking us to 80 * re-open the same file with a different mode. We allow this only 81 * if the modes are compatible. 82 */ 83 if (file == NULL) { 84 /* See comment below regarding freopen() of closed files. */ 85 if (fp->pub._flags == 0) { 86 FUNLOCKFILE(fp); 87 errno = EINVAL; 88 return (NULL); 89 } 90 if ((dflags = _fcntl(fp->pub._fileno, F_GETFL)) < 0) { 91 sverrno = errno; 92 fclose(fp); 93 FUNLOCKFILE(fp); 94 errno = sverrno; 95 return (NULL); 96 } 97 if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) != 98 (oflags & O_ACCMODE)) { 99 fclose(fp); 100 FUNLOCKFILE(fp); 101 errno = EINVAL; 102 return (NULL); 103 } 104 if ((oflags ^ dflags) & O_APPEND) { 105 dflags &= ~O_APPEND; 106 dflags |= oflags & O_APPEND; 107 if (_fcntl(fp->pub._fileno, F_SETFL, dflags) < 0) { 108 sverrno = errno; 109 fclose(fp); 110 FUNLOCKFILE(fp); 111 errno = sverrno; 112 return (NULL); 113 } 114 } 115 if (oflags & O_TRUNC) 116 ftruncate(fp->pub._fileno, 0); 117 if (_fseeko(fp, 0, oflags & O_APPEND ? SEEK_END : SEEK_SET) < 0 && 118 errno != ESPIPE) { 119 sverrno = errno; 120 fclose(fp); 121 FUNLOCKFILE(fp); 122 errno = sverrno; 123 return (NULL); 124 } 125 f = fp->pub._fileno; 126 isopen = 0; 127 wantfd = -1; 128 goto finish; 129 } 130 131 /* 132 * There are actually programs that depend on being able to "freopen" 133 * descriptors that weren't originally open. Keep this from breaking. 134 * Remember whether the stream was open to begin with, and which file 135 * descriptor (if any) was associated with it. If it was attached to 136 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin) 137 * should work. This is unnecessary if it was not a Unix file. 138 */ 139 if (fp->pub._flags == 0) { 140 fp->pub._flags = __SEOF; /* hold on to it */ 141 isopen = 0; 142 wantfd = -1; 143 } else { 144 /* flush the stream; ANSI doesn't require this. */ 145 if (fp->pub._flags & __SWR) 146 (void) __sflush(fp); 147 /* if close is NULL, closing is a no-op, hence pointless */ 148 isopen = fp->_close != NULL; 149 if ((wantfd = fp->pub._fileno) < 0 && isopen) { 150 (void) (*fp->_close)(fp->_cookie); 151 isopen = 0; 152 } 153 } 154 155 /* Get a new descriptor to refer to the new file. */ 156 f = _open(file, oflags, DEFFILEMODE); 157 if (f < 0 && isopen) { 158 /* If out of fd's close the old one and try again. */ 159 if (errno == ENFILE || errno == EMFILE) { 160 (void) (*fp->_close)(fp->_cookie); 161 isopen = 0; 162 f = _open(file, oflags, DEFFILEMODE); 163 } 164 } 165 sverrno = errno; 166 167 finish: 168 /* 169 * Finish closing fp. Even if the open succeeded above, we cannot 170 * keep fp->_base: it may be the wrong size. This loses the effect 171 * of any setbuffer calls, but stdio has always done this before. 172 */ 173 if (isopen) 174 (void) (*fp->_close)(fp->_cookie); 175 if (fp->pub._flags & __SMBF) 176 free((char *)fp->_bf._base); 177 fp->pub._w = 0; 178 fp->pub._r = 0; 179 fp->pub._p = NULL; 180 fp->_bf._base = NULL; 181 fp->_bf._size = 0; 182 fp->pub._lbfsize = 0; 183 if (HASUB(fp)) 184 FREEUB(fp); 185 fp->_ub._size = 0; 186 if (HASLB(fp)) 187 FREELB(fp); 188 fp->_lb._size = 0; 189 190 if (f < 0) { /* did not get it after all */ 191 fp->pub._flags = 0; /* set it free */ 192 errno = sverrno; /* restore in case _close clobbered */ 193 FUNLOCKFILE(fp); 194 return (NULL); 195 } 196 197 /* 198 * If reopening something that was open before on a real file, try 199 * to maintain the descriptor. Various C library routines (perror) 200 * assume stderr is always fd STDERR_FILENO, even if being freopen'd. 201 */ 202 if (wantfd >= 0 && f != wantfd) { 203 if (_dup2(f, wantfd) >= 0) { 204 (void)_close(f); 205 f = wantfd; 206 } 207 } 208 209 fp->pub._flags = flags; 210 fp->pub._fileno = f; 211 fp->_cookie = fp; 212 fp->_read = __sread; 213 fp->_write = __swrite; 214 fp->_seek = __sseek; 215 fp->_close = __sclose; 216 FUNLOCKFILE(fp); 217 return (fp); 218 } 219