2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 static char sccsid
[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95";
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD: head/bin/sh/redir.c 326025 2017-11-20 19:49:47Z pfg $");
43 #include <sys/types.h>
53 * Code for dealing with input/output redirection.
67 #define EMPTY -2 /* marks an unused slot in redirtab */
68 #define CLOSED -1 /* fd was not open before redir */
72 struct redirtab
*next
;
75 unsigned int empty_redirs
;
79 static struct redirtab
*redirlist
;
82 * We keep track of whether or not fd0 has been redirected. This is for
83 * background commands, where we want to redirect fd0 to /dev/null only
84 * if it hasn't already been redirected.
86 static int fd0_redirected
= 0;
88 /* Number of redirtabs that have not been allocated. */
89 static unsigned int empty_redirs
= 0;
91 static void openredirect(union node
*, char[10 ]);
92 static int openhere(union node
*);
96 * Process a list of redirection commands. If the REDIR_PUSH flag is set,
97 * old file descriptors are stashed away so that the redirection can be
98 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the
99 * standard output, and the standard error if it becomes a duplicate of
100 * stdout, is saved in memory.
102 * We suppress interrupts so that we won't leave open file
103 * descriptors around. Because the signal handler remains
104 * installed and we do not use system call restart, interrupts
105 * will still abort blocking opens such as fifos (they will fail
106 * with EINTR). There is, however, a race condition if an interrupt
107 * arrives after INTOFF and before open blocks.
111 redirect(union node
*redir
, int flags
)
114 struct redirtab
*sv
= NULL
;
117 char memory
[10]; /* file descriptors to write to memory */
120 for (i
= 10 ; --i
>= 0 ; )
122 memory
[1] = flags
& REDIR_BACKQ
;
123 if (flags
& REDIR_PUSH
) {
126 sv
= ckmalloc(sizeof (struct redirtab
));
127 for (i
= 0 ; i
< 10 ; i
++)
128 sv
->renamed
[i
] = EMPTY
;
129 sv
->fd0_redirected
= fd0_redirected
;
130 sv
->empty_redirs
= empty_redirs
- 1;
131 sv
->next
= redirlist
;
136 for (n
= redir
; n
; n
= n
->nfile
.next
) {
140 if ((n
->nfile
.type
== NTOFD
|| n
->nfile
.type
== NFROMFD
) &&
142 continue; /* redirect from/to same file descriptor */
144 if ((flags
& REDIR_PUSH
) && sv
->renamed
[fd
] == EMPTY
) {
146 if ((i
= fcntl(fd
, F_DUPFD_CLOEXEC_MAYBE
, 10)) == -1) {
153 error("%d: %s", fd
, strerror(errno
));
157 #if !defined(O_CLOEXEC) || !defined(F_DUPFD_CLOEXEC)
159 fcntl(i
, F_SETFD
, FD_CLOEXEC
);
165 openredirect(n
, memory
);
178 openredirect(union node
*redir
, char memory
[10])
181 int fd
= redir
->nfile
.fd
;
187 switch (redir
->nfile
.type
) {
189 fname
= redir
->nfile
.expfname
;
190 if ((f
= open(fname
, O_RDONLY
)) < 0)
191 error("cannot open %s: %s", fname
, strerror(errno
));
194 fname
= redir
->nfile
.expfname
;
195 if ((f
= open(fname
, O_RDWR
|O_CREAT
, 0666)) < 0)
196 error("cannot create %s: %s", fname
, strerror(errno
));
200 fname
= redir
->nfile
.expfname
;
201 if (stat(fname
, &sb
) == -1) {
202 if ((f
= open(fname
, O_WRONLY
|O_CREAT
|O_EXCL
, 0666)) < 0)
203 error("cannot create %s: %s", fname
, strerror(errno
));
204 } else if (!S_ISREG(sb
.st_mode
)) {
205 if ((f
= open(fname
, O_WRONLY
, 0666)) < 0)
206 error("cannot create %s: %s", fname
, strerror(errno
));
207 if (fstat(f
, &sb
) != -1 && S_ISREG(sb
.st_mode
)) {
209 error("cannot create %s: %s", fname
,
213 error("cannot create %s: %s", fname
,
219 fname
= redir
->nfile
.expfname
;
220 if ((f
= open(fname
, O_WRONLY
|O_CREAT
|O_TRUNC
, 0666)) < 0)
221 error("cannot create %s: %s", fname
, strerror(errno
));
224 fname
= redir
->nfile
.expfname
;
225 if ((f
= open(fname
, O_WRONLY
|O_CREAT
|O_APPEND
, 0666)) < 0)
226 error("cannot create %s: %s", fname
, strerror(errno
));
230 if (redir
->ndup
.dupfd
>= 0) { /* if not ">&-" */
231 if (memory
[redir
->ndup
.dupfd
])
234 if (dup2(redir
->ndup
.dupfd
, fd
) < 0)
235 error("%d: %s", redir
->ndup
.dupfd
,
250 if (dup2(f
, fd
) == -1) {
253 error("%d: %s", fd
, strerror(e
));
261 * Handle here documents. Normally we fork off a process to write the
262 * data to a pipe. If the document is short, we can stuff the data in
263 * the pipe without forking.
267 openhere(union node
*redir
)
276 error("Pipe call failed: %s", strerror(errno
));
278 if (redir
->type
== NXHERE
)
279 p
= redir
->nhere
.expdoc
;
281 p
= redir
->nhere
.doc
->narg
.text
;
285 flags
= fcntl(pip
[1], F_GETFL
, 0);
286 if (flags
!= -1 && fcntl(pip
[1], F_SETFL
, flags
| O_NONBLOCK
) != -1) {
287 written
= write(pip
[1], p
, len
);
290 if ((size_t)written
== len
)
292 fcntl(pip
[1], F_SETFL
, flags
);
295 if (forkshell((struct job
*)NULL
, (union node
*)NULL
, FORK_NOJOB
) == 0) {
297 signal(SIGINT
, SIG_IGN
);
298 signal(SIGQUIT
, SIG_IGN
);
299 signal(SIGHUP
, SIG_IGN
);
300 signal(SIGTSTP
, SIG_IGN
);
301 signal(SIGPIPE
, SIG_DFL
);
302 xwrite(pip
[1], p
+ written
, len
- written
);
313 * Undo the effects of the last redirection.
319 struct redirtab
*rp
= redirlist
;
323 if (empty_redirs
> 0) {
328 for (i
= 0 ; i
< 10 ; i
++) {
329 if (rp
->renamed
[i
] != EMPTY
) {
330 if (rp
->renamed
[i
] >= 0) {
331 dup2(rp
->renamed
[i
], i
);
332 close(rp
->renamed
[i
]);
338 fd0_redirected
= rp
->fd0_redirected
;
339 empty_redirs
= rp
->empty_redirs
;
340 redirlist
= rp
->next
;
345 /* Return true if fd 0 has already been redirected at least once. */
347 fd0_redirected_p(void)
349 return fd0_redirected
!= 0;
353 * Discard all saved file descriptors.
362 for (rp
= redirlist
; rp
; rp
= rp
->next
) {
363 for (i
= 0 ; i
< 10 ; i
++) {
364 if (rp
->renamed
[i
] >= 0) {
365 close(rp
->renamed
[i
]);
367 rp
->renamed
[i
] = EMPTY
;