HAMMER 60F/Many: Mirroring
[dragonfly.git] / lib / libc / stdio / freopen.c
blob39671169807cbd2434fdb6a6e1c79816c908069a
1 /*-
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
6 * Chris Torek.
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.
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.
36 * @(#)freopen.c 8.1 (Berkeley) 6/4/93
37 * $FreeBSD: src/lib/libc/stdio/freopen.c,v 1.5.2.1 2001/03/05 10:54:53 obrien Exp $
38 * $DragonFly: src/lib/libc/stdio/freopen.c,v 1.7 2005/11/20 11:07:30 swildner Exp $
41 #include "namespace.h"
42 #include <sys/types.h>
43 #include <sys/stat.h>
44 #include <fcntl.h>
45 #include <errno.h>
46 #include <unistd.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include "un-namespace.h"
51 #include "libc_private.h"
52 #include "local.h"
53 #include "priv_stdio.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.
60 FILE *
61 freopen(const char *file, const char *mode, FILE *fp)
63 int f;
64 int dflags, flags, isopen, oflags, sverrno, wantfd;
66 if ((flags = __sflags(mode, &oflags)) == 0) {
67 fclose(fp);
68 return (NULL);
71 FLOCKFILE(fp);
73 if (!__sdidinit)
74 __sinit();
76 sverrno = 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.
83 if (file == NULL) {
84 /* See comment below regarding freopen() of closed files. */
85 if (fp->pub._flags == 0) {
86 FUNLOCKFILE(fp);
87 errno = EINVAL;
88 return (NULL);
90 if ((dflags = _fcntl(fp->pub._fileno, F_GETFL)) < 0) {
91 sverrno = errno;
92 fclose(fp);
93 FUNLOCKFILE(fp);
94 errno = sverrno;
95 return (NULL);
97 if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) !=
98 (oflags & O_ACCMODE)) {
99 fclose(fp);
100 FUNLOCKFILE(fp);
101 errno = EINVAL;
102 return (NULL);
104 if ((oflags ^ dflags) & O_APPEND) {
105 dflags &= ~O_APPEND;
106 dflags |= oflags & O_APPEND;
107 if (_fcntl(fp->pub._fileno, F_SETFL, dflags) < 0) {
108 sverrno = errno;
109 fclose(fp);
110 FUNLOCKFILE(fp);
111 errno = sverrno;
112 return (NULL);
115 if (oflags & O_TRUNC)
116 ftruncate(fp->pub._fileno, 0);
117 if (_fseeko(fp, 0, oflags & O_APPEND ? SEEK_END : SEEK_SET) < 0 &&
118 errno != ESPIPE) {
119 sverrno = errno;
120 fclose(fp);
121 FUNLOCKFILE(fp);
122 errno = sverrno;
123 return (NULL);
125 f = fp->pub._fileno;
126 isopen = 0;
127 wantfd = -1;
128 goto finish;
132 * There are actually programs that depend on being able to "freopen"
133 * descriptors that weren't originally open. Keep this from breaking.
134 * Remember whether the stream was open to begin with, and which file
135 * descriptor (if any) was associated with it. If it was attached to
136 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
137 * should work. This is unnecessary if it was not a Unix file.
139 if (fp->pub._flags == 0) {
140 fp->pub._flags = __SEOF; /* hold on to it */
141 isopen = 0;
142 wantfd = -1;
143 } else {
144 /* flush the stream; ANSI doesn't require this. */
145 if (fp->pub._flags & __SWR)
146 __sflush(fp);
147 /* if close is NULL, closing is a no-op, hence pointless */
148 isopen = fp->_close != NULL;
149 if ((wantfd = fp->pub._fileno) < 0 && isopen) {
150 (*fp->_close)(fp->_cookie);
151 isopen = 0;
155 /* Get a new descriptor to refer to the new file. */
156 f = _open(file, oflags, DEFFILEMODE);
157 if (f < 0 && isopen) {
158 /* If out of fd's close the old one and try again. */
159 if (errno == ENFILE || errno == EMFILE) {
160 (*fp->_close)(fp->_cookie);
161 isopen = 0;
162 f = _open(file, oflags, DEFFILEMODE);
165 sverrno = errno;
167 finish:
169 * Finish closing fp. Even if the open succeeded above, we cannot
170 * keep fp->_base: it may be the wrong size. This loses the effect
171 * of any setbuffer calls, but stdio has always done this before.
173 if (isopen)
174 (*fp->_close)(fp->_cookie);
175 if (fp->pub._flags & __SMBF)
176 free((char *)fp->_bf._base);
177 fp->pub._w = 0;
178 fp->pub._r = 0;
179 fp->pub._p = NULL;
180 fp->_bf._base = NULL;
181 fp->_bf._size = 0;
182 fp->pub._lbfsize = 0;
183 if (HASUB(fp))
184 FREEUB(fp);
185 fp->_ub._size = 0;
186 if (HASLB(fp))
187 FREELB(fp);
188 fp->_lb._size = 0;
190 if (f < 0) { /* did not get it after all */
191 fp->pub._flags = 0; /* set it free */
192 errno = sverrno; /* restore in case _close clobbered */
193 FUNLOCKFILE(fp);
194 return (NULL);
198 * If reopening something that was open before on a real file, try
199 * to maintain the descriptor. Various C library routines (perror)
200 * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
202 if (wantfd >= 0 && f != wantfd) {
203 if (_dup2(f, wantfd) >= 0) {
204 _close(f);
205 f = wantfd;
209 fp->pub._flags = flags;
210 fp->pub._fileno = f;
211 fp->_cookie = fp;
212 fp->_read = __sread;
213 fp->_write = __swrite;
214 fp->_seek = __sseek;
215 fp->_close = __sclose;
216 FUNLOCKFILE(fp);
217 return (fp);