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) 34static 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: src/lib/libc/stdio/freopen.c,v 1.21 2008/04/17 22:17:54 jhb Exp $"); 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 <limits.h> 45#include <unistd.h> 46#include <stdio.h> 47#include <stdlib.h> 48#include "un-namespace.h" 49#include "libc_private.h" 50#include "local.h" 51 52/* 53 * Re-direct an existing, open (probably) file to some other file. 54 * ANSI is written such that the original file gets closed if at 55 * all possible, no matter what. 56 */ 57FILE * 58freopen(file, mode, fp) 59 const char * __restrict file; 60 const char * __restrict mode; 61 FILE *fp; 62{ 63 int f; 64 int dflags, flags, isopen, oflags, sverrno, wantfd; 65 66 if ((flags = __sflags(mode, &oflags)) == 0) { 67 sverrno = errno; 68 (void) fclose(fp); 69 errno = sverrno; 70 return (NULL); 71 } 72 73 pthread_once(&__sdidinit, __sinit); 74 75 FLOCKFILE(fp); 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 = EBADF; 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 * For UNIX03, we always close if it was open. 135 */ 136 if (fp->_flags == 0) { 137 fp->_flags = __SEOF; /* hold on to it */ 138 isopen = 0; 139 wantfd = -1; 140 } else { 141 /* flush the stream; ANSI doesn't require this. */ 142 if (fp->_flags & __SWR) 143 (void) __sflush(fp); 144 /* if close is NULL, closing is a no-op, hence pointless */ 145#if __DARWIN_UNIX03 146 if (fp->_close) 147 (void) (*fp->_close)(fp->_cookie); 148 isopen = 0; 149 wantfd = -1; 150#else /* !__DARWIN_UNIX03 */ 151 isopen = fp->_close != NULL; 152 if ((wantfd = fp->_file) < 0 && isopen) { 153 (void) (*fp->_close)(fp->_cookie); 154 isopen = 0; 155 } 156#endif /* __DARWIN_UNIX03 */ 157 } 158 159 /* Get a new descriptor to refer to the new file. */ 160 f = _open(file, oflags, DEFFILEMODE); 161 if (f < 0 && isopen) { 162 /* If out of fd's close the old one and try again. */ 163 if (errno == ENFILE || errno == EMFILE) { 164 (void) (*fp->_close)(fp->_cookie); 165 isopen = 0; 166 f = _open(file, oflags, DEFFILEMODE); 167 } 168 } 169 sverrno = errno; 170 171finish: 172 /* 173 * Finish closing fp. Even if the open succeeded above, we cannot 174 * keep fp->_base: it may be the wrong size. This loses the effect 175 * of any setbuffer calls, but stdio has always done this before. 176 */ 177 if (isopen) 178 (void) (*fp->_close)(fp->_cookie); 179 if (fp->_flags & __SMBF) 180 free((char *)fp->_bf._base); 181 fp->_w = 0; 182 fp->_r = 0; 183 fp->_p = NULL; 184 fp->_bf._base = NULL; 185 fp->_bf._size = 0; 186 fp->_lbfsize = 0; 187 if (HASUB(fp)) 188 FREEUB(fp); 189 fp->_ub._size = 0; 190 if (HASLB(fp)) 191 FREELB(fp); 192 fp->_lb._size = 0; 193 fp->_orientation = 0; 194 memset(&fp->_mbstate, 0, sizeof(mbstate_t)); 195 196 if (f < 0) { /* did not get it after all */ 197 FUNLOCKFILE(fp); 198 __sfprelease(fp); /* set it free */ 199 errno = sverrno; /* restore in case _close clobbered */ 200 return (NULL); 201 } 202 203 /* 204 * If reopening something that was open before on a real file, try 205 * to maintain the descriptor. Various C library routines (perror) 206 * assume stderr is always fd STDERR_FILENO, even if being freopen'd. 207 */ 208 if (wantfd >= 0 && f != wantfd) { 209 if (_dup2(f, wantfd) >= 0) { 210 (void)_close(f); 211 f = wantfd; 212 } 213 } 214 215 /* 216 * File descriptors are a full int, but _file is only a short. 217 * If we get a valid file descriptor that is greater than 218 * SHRT_MAX, then the fd will get sign-extended into an 219 * invalid file descriptor. Handle this case by failing the 220 * open. 221 */ 222 if (f > SHRT_MAX) { 223 FUNLOCKFILE(fp); 224 __sfprelease(fp); /* set it free */ 225 errno = EMFILE; 226 return (NULL); 227 } 228 229 fp->_flags = flags; 230 fp->_file = f; 231 fp->_cookie = fp; 232 fp->_read = __sread; 233 fp->_write = __swrite; 234 fp->_seek = __sseek; 235 fp->_close = __sclose; 236 /* 237 * When opening in append mode, even though we use O_APPEND, 238 * we need to seek to the end so that ftell() gets the right 239 * answer. If the user then alters the seek pointer, or 240 * the file extends, this will fail, but there is not much 241 * we can do about this. (We could set __SAPP and check in 242 * fseek and ftell.) 243 */ 244 if (oflags & O_APPEND) 245 (void) _sseek(fp, (fpos_t)0, SEEK_END); 246 FUNLOCKFILE(fp); 247 return (fp); 248} 249