2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
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25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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("$FreeBSD$");
39 #include "namespace.h"
40 #include <sys/types.h>
48 #include "un-namespace.h"
49 #include "libc_private.h"
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.
58 freopen(file, mode, fp)
59 const char * __restrict file;
60 const char * __restrict mode;
64 int dflags, flags, isopen, oflags, sverrno, wantfd;
66 if ((flags = __sflags(mode, &oflags)) == 0) {
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.
84 /* See comment below regarding freopen() of closed files. */
85 if (fp->_flags == 0) {
90 if ((dflags = _fcntl(fp->_file, F_GETFL)) < 0) {
97 if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) !=
98 (oflags & O_ACCMODE)) {
104 if (fp->_flags & __SWR)
106 if ((oflags ^ dflags) & O_APPEND) {
108 dflags |= oflags & O_APPEND;
109 if (_fcntl(fp->_file, F_SETFL, dflags) < 0) {
117 if (oflags & O_TRUNC)
118 (void) ftruncate(fp->_file, (off_t)0);
119 if (!(oflags & O_APPEND))
120 (void) _sseek(fp, (fpos_t)0, SEEK_SET);
121 if (oflags & O_CLOEXEC)
122 (void) _fcntl(fp->_file, F_SETFD, FD_CLOEXEC);
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.
137 if (fp->_flags == 0) {
138 fp->_flags = __SEOF; /* hold on to it */
142 /* flush the stream; ANSI doesn't require this. */
143 if (fp->_flags & __SWR)
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);
153 /* Get a new descriptor to refer to the new file. */
154 f = _open(file, oflags, DEFFILEMODE);
159 * Finish closing fp. Even if the open succeeded above, we cannot
160 * keep fp->_base: it may be the wrong size. This loses the effect
161 * of any setbuffer calls, but stdio has always done this before.
163 * Leave the existing file descriptor open until dup2() is called
164 * below to avoid races where a concurrent open() in another thread
165 * could claim the existing descriptor.
167 if (fp->_flags & __SMBF)
168 free((char *)fp->_bf._base);
172 fp->_bf._base = NULL;
181 fp->_orientation = 0;
182 memset(&fp->_mbstate, 0, sizeof(mbstate_t));
184 if (f < 0) { /* did not get it after all */
186 (void) (*fp->_close)(fp->_cookie);
187 fp->_flags = 0; /* set it free */
189 errno = sverrno; /* restore in case _close clobbered */
194 * If reopening something that was open before on a real file, try
195 * to maintain the descriptor. Various C library routines (perror)
196 * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
199 if ((oflags & O_CLOEXEC ? _fcntl(f, F_DUP2FD_CLOEXEC, wantfd) :
200 _dup2(f, wantfd)) >= 0) {
204 (void)_close(fp->_file);
208 * File descriptors are a full int, but _file is only a short.
209 * If we get a valid file descriptor that is greater than
210 * SHRT_MAX, then the fd will get sign-extended into an
211 * invalid file descriptor. Handle this case by failing the
215 fp->_flags = 0; /* set it free */
225 fp->_write = __swrite;
227 fp->_close = __sclose;
229 * When opening in append mode, even though we use O_APPEND,
230 * we need to seek to the end so that ftell() gets the right
231 * answer. If the user then alters the seek pointer, or
232 * the file extends, this will fail, but there is not much
233 * we can do about this. (We could set __SAPP and check in
236 if (oflags & O_APPEND)
237 (void) _sseek(fp, (fpos_t)0, SEEK_END);