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
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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
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15 * documentation and/or other materials provided with the distribution.
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17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
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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
32 * @(#)freopen.c 8.1 (Berkeley) 6/4/93
33 * $FreeBSD: src/lib/libc/stdio/freopen.c,v 1.21 2008/04/17 22:17:54 jhb Exp $
36 #include "namespace.h"
37 #include <sys/types.h>
44 #include "un-namespace.h"
45 #include "libc_private.h"
49 * Re-direct an existing, open (probably) file to some other file.
50 * ANSI is written such that the original file gets closed if at
51 * all possible, no matter what.
54 freopen(const char * __restrict file
, const char * __restrict mode
, FILE *fp
)
57 int dflags
, flags
, isopen
, oflags
, sverrno
, wantfd
;
59 if ((flags
= __sflags(mode
, &oflags
)) == 0) {
72 * If the filename is a NULL pointer, the caller is asking us to
73 * re-open the same file with a different mode. We allow this only
74 * if the modes are compatible.
77 /* See comment below regarding freopen() of closed files. */
78 if (fp
->pub
._flags
== 0) {
83 if ((dflags
= _fcntl(fp
->pub
._fileno
, F_GETFL
)) < 0) {
90 if ((dflags
& O_ACCMODE
) != O_RDWR
&& (dflags
& O_ACCMODE
) !=
91 (oflags
& O_ACCMODE
)) {
97 if (fp
->pub
._flags
& __SWR
)
99 if ((oflags
^ dflags
) & O_APPEND
) {
101 dflags
|= oflags
& O_APPEND
;
102 if (_fcntl(fp
->pub
._fileno
, F_SETFL
, dflags
) < 0) {
110 if (oflags
& O_TRUNC
)
111 ftruncate(fp
->pub
._fileno
, (off_t
)0);
112 if (!(oflags
& O_APPEND
))
113 _sseek(fp
, (fpos_t)0, SEEK_SET
);
114 if (oflags
& O_CLOEXEC
)
115 _fcntl(fileno(fp
), F_SETFD
, FD_CLOEXEC
);
124 * There are actually programs that depend on being able to "freopen"
125 * descriptors that weren't originally open. Keep this from breaking.
126 * Remember whether the stream was open to begin with, and which file
127 * descriptor (if any) was associated with it. If it was attached to
128 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
129 * should work. This is unnecessary if it was not a Unix file.
131 if (fp
->pub
._flags
== 0) {
132 fp
->pub
._flags
= __SEOF
; /* hold on to it */
136 /* flush the stream; ANSI doesn't require this. */
137 if (fp
->pub
._flags
& __SWR
)
139 /* if close is NULL, closing is a no-op, hence pointless */
140 isopen
= fp
->_close
!= NULL
;
141 if ((wantfd
= fp
->pub
._fileno
) < 0 && isopen
) {
142 (*fp
->_close
)(fp
->_cookie
);
147 /* Get a new descriptor to refer to the new file. */
148 f
= _open(file
, oflags
, DEFFILEMODE
);
149 if (f
< 0 && isopen
) {
150 /* If out of fd's close the old one and try again. */
151 if (errno
== ENFILE
|| errno
== EMFILE
) {
152 (*fp
->_close
)(fp
->_cookie
);
154 f
= _open(file
, oflags
, DEFFILEMODE
);
161 * Finish closing fp. Even if the open succeeded above, we cannot
162 * keep fp->_base: it may be the wrong size. This loses the effect
163 * of any setbuffer calls, but stdio has always done this before.
166 (*fp
->_close
)(fp
->_cookie
);
167 if (fp
->pub
._flags
& __SMBF
)
168 free((char *)fp
->_bf
._base
);
172 fp
->_bf
._base
= NULL
;
174 fp
->pub
._lbfsize
= 0;
181 memset(WCIO_GET(fp
), 0, sizeof(struct wchar_io_data
));
183 if (f
< 0) { /* did not get it after all */
184 fp
->pub
._flags
= 0; /* set it free */
186 errno
= sverrno
; /* restore in case _close clobbered */
191 * If reopening something that was open before on a real file, try
192 * to maintain the descriptor. Various C library routines (perror)
193 * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
195 if (wantfd
>= 0 && f
!= wantfd
) {
196 if (oflags
& O_CLOEXEC
) {
197 if (_fcntl(f
, F_DUP2FD_CLOEXEC
, wantfd
) >= 0) {
202 if (_dup2(f
, wantfd
) >= 0) {
209 fp
->pub
._flags
= flags
;
213 fp
->_write
= __swrite
;
215 fp
->_close
= __sclose
;
217 * When opening in append mode, even though we use O_APPEND,
218 * we need to seek to the end so that ftell() gets the right
219 * answer. If the user then alters the seek pointer, or
220 * the file extends, this will fail, but there is not much
221 * we can do about this. (We could set __SAPP and check in
224 if (oflags
& O_APPEND
)
225 _sseek(fp
, (fpos_t)0, SEEK_END
);