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 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include "namespace.h" 40 #include <sys/types.h> 41 #include <sys/stat.h> 42 #include <fcntl.h> 43 #include <errno.h> 44 #include <unistd.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include "un-namespace.h" 48 #include "libc_private.h" 49 #include "local.h" 50 51 /* 52 * Re-direct an existing, open (probably) file to some other file. 53 * ANSI is written such that the original file gets closed if at 54 * all possible, no matter what. 55 */ 56 FILE * 57 freopen(file, mode, fp) 58 const char * __restrict file; 59 const char * __restrict mode; 60 FILE *fp; 61 { 62 int f; 63 int dflags, flags, isopen, oflags, sverrno, wantfd; 64 65 if ((flags = __sflags(mode, &oflags)) == 0) { 66 sverrno = errno; 67 (void) fclose(fp); 68 errno = sverrno; 69 return (NULL); 70 } 71 72 FLOCKFILE(fp); 73 74 if (!__sdidinit) 75 __sinit(); 76 77 /* 78 * If the filename is a NULL pointer, the caller is asking us to 79 * re-open the same file with a different mode. We allow this only 80 * if the modes are compatible. 81 */ 82 if (file == NULL) { 83 /* See comment below regarding freopen() of closed files. */ 84 if (fp->_flags == 0) { 85 FUNLOCKFILE(fp); 86 errno = EINVAL; 87 return (NULL); 88 } 89 if ((dflags = _fcntl(fp->_file, F_GETFL)) < 0) { 90 sverrno = errno; 91 fclose(fp); 92 FUNLOCKFILE(fp); 93 errno = sverrno; 94 return (NULL); 95 } 96 if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) != 97 (oflags & O_ACCMODE)) { 98 fclose(fp); 99 FUNLOCKFILE(fp); 100 errno = EINVAL; 101 return (NULL); 102 } 103 if (fp->_flags & __SWR) 104 (void) __sflush(fp); 105 if ((oflags ^ dflags) & O_APPEND) { 106 dflags &= ~O_APPEND; 107 dflags |= oflags & O_APPEND; 108 if (_fcntl(fp->_file, F_SETFL, dflags) < 0) { 109 sverrno = errno; 110 fclose(fp); 111 FUNLOCKFILE(fp); 112 errno = sverrno; 113 return (NULL); 114 } 115 } 116 if (oflags & O_TRUNC) 117 (void) ftruncate(fp->_file, (off_t)0); 118 if (!(oflags & O_APPEND)) 119 (void) _sseek(fp, (fpos_t)0, SEEK_SET); 120 f = fp->_file; 121 isopen = 0; 122 wantfd = -1; 123 goto finish; 124 } 125 126 /* 127 * There are actually programs that depend on being able to "freopen" 128 * descriptors that weren't originally open. Keep this from breaking. 129 * Remember whether the stream was open to begin with, and which file 130 * descriptor (if any) was associated with it. If it was attached to 131 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin) 132 * should work. This is unnecessary if it was not a Unix file. 133 */ 134 if (fp->_flags == 0) { 135 fp->_flags = __SEOF; /* hold on to it */ 136 isopen = 0; 137 wantfd = -1; 138 } else { 139 /* flush the stream; ANSI doesn't require this. */ 140 if (fp->_flags & __SWR) 141 (void) __sflush(fp); 142 /* if close is NULL, closing is a no-op, hence pointless */ 143 isopen = fp->_close != NULL; 144 if ((wantfd = fp->_file) < 0 && isopen) { 145 (void) (*fp->_close)(fp->_cookie); 146 isopen = 0; 147 } 148 } 149 150 /* Get a new descriptor to refer to the new file. */ 151 f = _open(file, oflags, DEFFILEMODE); 152 if (f < 0 && isopen) { 153 /* If out of fd's close the old one and try again. */ 154 if (errno == ENFILE || errno == EMFILE) { 155 (void) (*fp->_close)(fp->_cookie); 156 isopen = 0; 157 f = _open(file, oflags, DEFFILEMODE); 158 } 159 } 160 sverrno = errno; 161 162 finish: 163 /* 164 * Finish closing fp. Even if the open succeeded above, we cannot 165 * keep fp->_base: it may be the wrong size. This loses the effect 166 * of any setbuffer calls, but stdio has always done this before. 167 */ 168 if (isopen) 169 (void) (*fp->_close)(fp->_cookie); 170 if (fp->_flags & __SMBF) 171 free((char *)fp->_bf._base); 172 fp->_w = 0; 173 fp->_r = 0; 174 fp->_p = NULL; 175 fp->_bf._base = NULL; 176 fp->_bf._size = 0; 177 fp->_lbfsize = 0; 178 if (HASUB(fp)) 179 FREEUB(fp); 180 fp->_ub._size = 0; 181 if (HASLB(fp)) 182 FREELB(fp); 183 fp->_lb._size = 0; 184 fp->_extra->orientation = 0; 185 memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t)); 186 187 if (f < 0) { /* did not get it after all */ 188 fp->_flags = 0; /* set it free */ 189 FUNLOCKFILE(fp); 190 errno = sverrno; /* restore in case _close clobbered */ 191 return (NULL); 192 } 193 194 /* 195 * If reopening something that was open before on a real file, try 196 * to maintain the descriptor. Various C library routines (perror) 197 * assume stderr is always fd STDERR_FILENO, even if being freopen'd. 198 */ 199 if (wantfd >= 0 && f != wantfd) { 200 if (_dup2(f, wantfd) >= 0) { 201 (void)_close(f); 202 f = wantfd; 203 } 204 } 205 206 fp->_flags = flags; 207 fp->_file = f; 208 fp->_cookie = fp; 209 fp->_read = __sread; 210 fp->_write = __swrite; 211 fp->_seek = __sseek; 212 fp->_close = __sclose; 213 /* 214 * When opening in append mode, even though we use O_APPEND, 215 * we need to seek to the end so that ftell() gets the right 216 * answer. If the user then alters the seek pointer, or 217 * the file extends, this will fail, but there is not much 218 * we can do about this. (We could set __SAPP and check in 219 * fseek and ftell.) 220 */ 221 if (oflags & O_APPEND) 222 (void) _sseek(fp, (fpos_t)0, SEEK_END); 223 FUNLOCKFILE(fp); 224 return (fp); 225 } 226