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 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93"; 39 #endif /* LIBC_SCCS and not lint */ 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "namespace.h" 44 #include <sys/types.h> 45 #include <sys/stat.h> 46 #include <fcntl.h> 47 #include <errno.h> 48 #include <unistd.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include "un-namespace.h" 52 #include "libc_private.h" 53 #include "local.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(file, mode, fp) 62 const char * __restrict file; 63 const char * __restrict mode; 64 FILE *fp; 65 { 66 int f; 67 int dflags, flags, isopen, oflags, sverrno, wantfd; 68 69 if ((flags = __sflags(mode, &oflags)) == 0) { 70 sverrno = errno; 71 (void) fclose(fp); 72 errno = sverrno; 73 return (NULL); 74 } 75 76 FLOCKFILE(fp); 77 78 if (!__sdidinit) 79 __sinit(); 80 81 /* 82 * If the filename is a NULL pointer, the caller is asking us to 83 * re-open the same file with a different mode. We allow this only 84 * if the modes are compatible. 85 */ 86 if (file == NULL) { 87 /* See comment below regarding freopen() of closed files. */ 88 if (fp->_flags == 0) { 89 FUNLOCKFILE(fp); 90 errno = EINVAL; 91 return (NULL); 92 } 93 if ((dflags = _fcntl(fp->_file, F_GETFL)) < 0) { 94 sverrno = errno; 95 fclose(fp); 96 FUNLOCKFILE(fp); 97 errno = sverrno; 98 return (NULL); 99 } 100 if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) != 101 (oflags & O_ACCMODE)) { 102 fclose(fp); 103 FUNLOCKFILE(fp); 104 errno = EINVAL; 105 return (NULL); 106 } 107 if (fp->_flags & __SWR) 108 (void) __sflush(fp); 109 if ((oflags ^ dflags) & O_APPEND) { 110 dflags &= ~O_APPEND; 111 dflags |= oflags & O_APPEND; 112 if (_fcntl(fp->_file, F_SETFL, dflags) < 0) { 113 sverrno = errno; 114 fclose(fp); 115 FUNLOCKFILE(fp); 116 errno = sverrno; 117 return (NULL); 118 } 119 } 120 if (oflags & O_TRUNC) 121 (void) ftruncate(fp->_file, (off_t)0); 122 if (!(oflags & O_APPEND)) 123 (void) _sseek(fp, (fpos_t)0, SEEK_SET); 124 f = fp->_file; 125 isopen = 0; 126 wantfd = -1; 127 goto finish; 128 } 129 130 /* 131 * There are actually programs that depend on being able to "freopen" 132 * descriptors that weren't originally open. Keep this from breaking. 133 * Remember whether the stream was open to begin with, and which file 134 * descriptor (if any) was associated with it. If it was attached to 135 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin) 136 * should work. This is unnecessary if it was not a Unix file. 137 */ 138 if (fp->_flags == 0) { 139 fp->_flags = __SEOF; /* hold on to it */ 140 isopen = 0; 141 wantfd = -1; 142 } else { 143 /* flush the stream; ANSI doesn't require this. */ 144 if (fp->_flags & __SWR) 145 (void) __sflush(fp); 146 /* if close is NULL, closing is a no-op, hence pointless */ 147 isopen = fp->_close != NULL; 148 if ((wantfd = fp->_file) < 0 && isopen) { 149 (void) (*fp->_close)(fp->_cookie); 150 isopen = 0; 151 } 152 } 153 154 /* Get a new descriptor to refer to the new file. */ 155 f = _open(file, oflags, DEFFILEMODE); 156 if (f < 0 && isopen) { 157 /* If out of fd's close the old one and try again. */ 158 if (errno == ENFILE || errno == EMFILE) { 159 (void) (*fp->_close)(fp->_cookie); 160 isopen = 0; 161 f = _open(file, oflags, DEFFILEMODE); 162 } 163 } 164 sverrno = errno; 165 166 finish: 167 /* 168 * Finish closing fp. Even if the open succeeded above, we cannot 169 * keep fp->_base: it may be the wrong size. This loses the effect 170 * of any setbuffer calls, but stdio has always done this before. 171 */ 172 if (isopen) 173 (void) (*fp->_close)(fp->_cookie); 174 if (fp->_flags & __SMBF) 175 free((char *)fp->_bf._base); 176 fp->_w = 0; 177 fp->_r = 0; 178 fp->_p = NULL; 179 fp->_bf._base = NULL; 180 fp->_bf._size = 0; 181 fp->_lbfsize = 0; 182 if (HASUB(fp)) 183 FREEUB(fp); 184 fp->_ub._size = 0; 185 if (HASLB(fp)) 186 FREELB(fp); 187 fp->_lb._size = 0; 188 fp->_extra->orientation = 0; 189 memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t)); 190 191 if (f < 0) { /* did not get it after all */ 192 fp->_flags = 0; /* set it free */ 193 FUNLOCKFILE(fp); 194 errno = sverrno; /* restore in case _close clobbered */ 195 return (NULL); 196 } 197 198 /* 199 * If reopening something that was open before on a real file, try 200 * to maintain the descriptor. Various C library routines (perror) 201 * assume stderr is always fd STDERR_FILENO, even if being freopen'd. 202 */ 203 if (wantfd >= 0 && f != wantfd) { 204 if (_dup2(f, wantfd) >= 0) { 205 (void)_close(f); 206 f = wantfd; 207 } 208 } 209 210 fp->_flags = flags; 211 fp->_file = f; 212 fp->_cookie = fp; 213 fp->_read = __sread; 214 fp->_write = __swrite; 215 fp->_seek = __sseek; 216 fp->_close = __sclose; 217 /* 218 * When opening in append mode, even though we use O_APPEND, 219 * we need to seek to the end so that ftell() gets the right 220 * answer. If the user then alters the seek pointer, or 221 * the file extends, this will fail, but there is not much 222 * we can do about this. (We could set __SAPP and check in 223 * fseek and ftell.) 224 */ 225 if (oflags & O_APPEND) 226 (void) _sseek(fp, (fpos_t)0, SEEK_END); 227 FUNLOCKFILE(fp); 228 return (fp); 229 } 230