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 1.5 2005/01/31 22:29:40 dillon 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 #include "libc_private.h" 51 #include "local.h" 52 53 /* 54 * Re-direct an existing, open (probably) file to some other file. 55 * ANSI is written such that the original file gets closed if at 56 * all possible, no matter what. 57 */ 58 FILE * 59 freopen(const char *file, const char *mode, FILE *fp) 60 { 61 int f; 62 int dflags, flags, isopen, oflags, sverrno, wantfd; 63 64 if ((flags = __sflags(mode, &oflags)) == 0) { 65 (void) fclose(fp); 66 return (NULL); 67 } 68 69 FLOCKFILE(fp); 70 71 if (!__sdidinit) 72 __sinit(); 73 74 sverrno = 0; 75 76 /* 77 * If the filename is a NULL pointer, the caller is asking us to 78 * re-open the same file with a different mode. We allow this only 79 * if the modes are compatible. 80 */ 81 if (file == NULL) { 82 /* See comment below regarding freopen() of closed files. */ 83 if (fp->_flags == 0) { 84 FUNLOCKFILE(fp); 85 errno = EINVAL; 86 return (NULL); 87 } 88 if ((dflags = fcntl(fp->_file, F_GETFL)) < 0) { 89 sverrno = errno; 90 fclose(fp); 91 FUNLOCKFILE(fp); 92 errno = sverrno; 93 return (NULL); 94 } 95 if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) != 96 (oflags & O_ACCMODE)) { 97 fclose(fp); 98 FUNLOCKFILE(fp); 99 errno = EINVAL; 100 return (NULL); 101 } 102 if ((oflags ^ dflags) & O_APPEND) { 103 dflags &= ~O_APPEND; 104 dflags |= oflags & O_APPEND; 105 if (fcntl(fp->_file, F_SETFL, dflags) < 0) { 106 sverrno = errno; 107 fclose(fp); 108 FUNLOCKFILE(fp); 109 errno = sverrno; 110 return (NULL); 111 } 112 } 113 if (oflags & O_TRUNC) 114 ftruncate(fp->_file, 0); 115 if (_fseeko(fp, 0, oflags & O_APPEND ? SEEK_END : SEEK_SET) < 0 && 116 errno != ESPIPE) { 117 sverrno = errno; 118 fclose(fp); 119 FUNLOCKFILE(fp); 120 errno = sverrno; 121 return (NULL); 122 } 123 f = fp->_file; 124 isopen = 0; 125 wantfd = -1; 126 goto finish; 127 } 128 129 /* 130 * There are actually programs that depend on being able to "freopen" 131 * descriptors that weren't originally open. Keep this from breaking. 132 * Remember whether the stream was open to begin with, and which file 133 * descriptor (if any) was associated with it. If it was attached to 134 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin) 135 * should work. This is unnecessary if it was not a Unix file. 136 */ 137 if (fp->_flags == 0) { 138 fp->_flags = __SEOF; /* hold on to it */ 139 isopen = 0; 140 wantfd = -1; 141 } else { 142 /* flush the stream; ANSI doesn't require this. */ 143 if (fp->_flags & __SWR) 144 (void) __sflush(fp); 145 /* if close is NULL, closing is a no-op, hence pointless */ 146 isopen = fp->_close != NULL; 147 if ((wantfd = fp->_file) < 0 && isopen) { 148 (void) (*fp->_close)(fp->_cookie); 149 isopen = 0; 150 } 151 } 152 153 /* Get a new descriptor to refer to the new file. */ 154 f = _open(file, oflags, DEFFILEMODE); 155 if (f < 0 && isopen) { 156 /* If out of fd's close the old one and try again. */ 157 if (errno == ENFILE || errno == EMFILE) { 158 (void) (*fp->_close)(fp->_cookie); 159 isopen = 0; 160 f = _open(file, oflags, DEFFILEMODE); 161 } 162 } 163 sverrno = errno; 164 165 finish: 166 /* 167 * Finish closing fp. Even if the open succeeded above, we cannot 168 * keep fp->_base: it may be the wrong size. This loses the effect 169 * of any setbuffer calls, but stdio has always done this before. 170 */ 171 if (isopen) 172 (void) (*fp->_close)(fp->_cookie); 173 if (fp->_flags & __SMBF) 174 free((char *)fp->_bf._base); 175 fp->_w = 0; 176 fp->_r = 0; 177 fp->_p = NULL; 178 fp->_bf._base = NULL; 179 fp->_bf._size = 0; 180 fp->_lbfsize = 0; 181 if (HASUB(fp)) 182 FREEUB(fp); 183 fp->_ub._size = 0; 184 if (HASLB(fp)) 185 FREELB(fp); 186 fp->_lb._size = 0; 187 188 if (f < 0) { /* did not get it after all */ 189 fp->_flags = 0; /* set it free */ 190 errno = sverrno; /* restore in case _close clobbered */ 191 FUNLOCKFILE(fp); 192 return (NULL); 193 } 194 195 /* 196 * If reopening something that was open before on a real file, try 197 * to maintain the descriptor. Various C library routines (perror) 198 * assume stderr is always fd STDERR_FILENO, even if being freopen'd. 199 */ 200 if (wantfd >= 0 && f != wantfd) { 201 if (_dup2(f, wantfd) >= 0) { 202 (void)_close(f); 203 f = wantfd; 204 } 205 } 206 207 fp->_flags = flags; 208 fp->_file = f; 209 fp->_cookie = fp; 210 fp->_read = __sread; 211 fp->_write = __swrite; 212 fp->_seek = __sseek; 213 fp->_close = __sclose; 214 FUNLOCKFILE(fp); 215 return (fp); 216 } 217