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
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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.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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37 #if defined(LIBC_SCCS) && !defined(lint)
39 static char sccsid[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93";
41 static const char rcsid[] =
42 "$FreeBSD: src/lib/libc/stdio/freopen.c,v 1.5.2.1 2001/03/05 10:54:53 obrien Exp $";
43 #endif /* LIBC_SCCS and not lint */
45 #include <sys/types.h>
52 #include "libc_private.h"
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.
61 freopen(file, mode, fp)
62 const char *file, *mode;
66 int flags, isopen, oflags, sverrno, wantfd;
68 if ((flags = __sflags(mode, &oflags)) == 0) {
79 * There are actually programs that depend on being able to "freopen"
80 * descriptors that weren't originally open. Keep this from breaking.
81 * Remember whether the stream was open to begin with, and which file
82 * descriptor (if any) was associated with it. If it was attached to
83 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
84 * should work. This is unnecessary if it was not a Unix file.
86 if (fp->_flags == 0) {
87 fp->_flags = __SEOF; /* hold on to it */
91 /* flush the stream; ANSI doesn't require this. */
92 if (fp->_flags & __SWR)
94 /* if close is NULL, closing is a no-op, hence pointless */
95 isopen = fp->_close != NULL;
96 if ((wantfd = fp->_file) < 0 && isopen) {
97 (void) (*fp->_close)(fp->_cookie);
102 /* Get a new descriptor to refer to the new file. */
103 f = _open(file, oflags, DEFFILEMODE);
104 if (f < 0 && isopen) {
105 /* If out of fd's close the old one and try again. */
106 if (errno == ENFILE || errno == EMFILE) {
107 (void) (*fp->_close)(fp->_cookie);
109 f = _open(file, oflags, DEFFILEMODE);
115 * Finish closing fp. Even if the open succeeded above, we cannot
116 * keep fp->_base: it may be the wrong size. This loses the effect
117 * of any setbuffer calls, but stdio has always done this before.
120 (void) (*fp->_close)(fp->_cookie);
121 if (fp->_flags & __SMBF)
122 free((char *)fp->_bf._base);
126 fp->_bf._base = NULL;
136 if (f < 0) { /* did not get it after all */
137 fp->_flags = 0; /* set it free */
138 errno = sverrno; /* restore in case _close clobbered */
144 * If reopening something that was open before on a real file, try
145 * to maintain the descriptor. Various C library routines (perror)
146 * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
148 if (wantfd >= 0 && f != wantfd) {
149 if (dup2(f, wantfd) >= 0) {
159 fp->_write = __swrite;
161 fp->_close = __sclose;