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 * 3. 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
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
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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(const char * __restrict file, const char * __restrict mode,
62 int dflags, flags, isopen, oflags, sverrno, wantfd;
64 if ((flags = __sflags(mode, &oflags)) == 0) {
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.
82 /* See comment below regarding freopen() of closed files. */
83 if (fp->_flags == 0) {
88 if ((dflags = _fcntl(fp->_file, F_GETFL)) < 0) {
95 if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) !=
96 (oflags & O_ACCMODE)) {
102 if (fp->_flags & __SWR)
104 if ((oflags ^ dflags) & O_APPEND) {
106 dflags |= oflags & O_APPEND;
107 if (_fcntl(fp->_file, F_SETFL, dflags) < 0) {
115 if (oflags & O_TRUNC)
116 (void) ftruncate(fp->_file, (off_t)0);
117 if (!(oflags & O_APPEND))
118 (void) _sseek(fp, (fpos_t)0, SEEK_SET);
119 if (oflags & O_CLOEXEC)
120 (void) _fcntl(fp->_file, F_SETFD, FD_CLOEXEC);
128 * There are actually programs that depend on being able to "freopen"
129 * descriptors that weren't originally open. Keep this from breaking.
130 * Remember whether the stream was open to begin with, and which file
131 * descriptor (if any) was associated with it. If it was attached to
132 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
133 * should work. This is unnecessary if it was not a Unix file.
135 if (fp->_flags == 0) {
136 fp->_flags = __SEOF; /* hold on to it */
140 /* flush the stream; ANSI doesn't require this. */
141 if (fp->_flags & __SWR)
143 /* if close is NULL, closing is a no-op, hence pointless */
144 isopen = fp->_close != NULL;
145 if ((wantfd = fp->_file) < 0 && isopen) {
146 (void) (*fp->_close)(fp->_cookie);
151 /* Get a new descriptor to refer to the new file. */
152 f = _open(file, oflags, DEFFILEMODE);
157 * Finish closing fp. Even if the open succeeded above, we cannot
158 * keep fp->_base: it may be the wrong size. This loses the effect
159 * of any setbuffer calls, but stdio has always done this before.
161 * Leave the existing file descriptor open until dup2() is called
162 * below to avoid races where a concurrent open() in another thread
163 * could claim the existing descriptor.
165 if (fp->_flags & __SMBF)
166 free((char *)fp->_bf._base);
170 fp->_bf._base = NULL;
179 fp->_orientation = 0;
180 memset(&fp->_mbstate, 0, sizeof(mbstate_t));
182 if (f < 0) { /* did not get it after all */
184 (void) (*fp->_close)(fp->_cookie);
185 fp->_flags = 0; /* set it free */
187 errno = sverrno; /* restore in case _close clobbered */
192 * If reopening something that was open before on a real file, try
193 * to maintain the descriptor. Various C library routines (perror)
194 * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
197 if ((oflags & O_CLOEXEC ? _fcntl(f, F_DUP2FD_CLOEXEC, wantfd) :
198 _dup2(f, wantfd)) >= 0) {
202 (void)_close(fp->_file);
206 * File descriptors are a full int, but _file is only a short.
207 * If we get a valid file descriptor that is greater than
208 * SHRT_MAX, then the fd will get sign-extended into an
209 * invalid file descriptor. Handle this case by failing the
213 fp->_flags = 0; /* set it free */
223 fp->_write = __swrite;
225 fp->_close = __sclose;
227 * When opening in append mode, even though we use O_APPEND,
228 * we need to seek to the end so that ftell() gets the right
229 * answer. If the user then alters the seek pointer, or
230 * the file extends, this will fail, but there is not much
231 * we can do about this. (We could set __SAPP and check in
234 if (oflags & O_APPEND)
235 (void) _sseek(fp, (fpos_t)0, SEEK_END);