redir.c revision 21673 
1/*-
2 * Copyright (c) 1991, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Kenneth Almquist.
7 *
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.
23 *
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.
35 *
36 *	$FreeBSD: head/bin/sh/redir.c 21673 1997-01-14 07:20:47Z jkh $
37 */
38
39#ifndef lint
40static char const sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
41#endif /* not lint */
42
43#include <sys/types.h>
44#include <signal.h>
45#include <string.h>
46#include <fcntl.h>
47#include <errno.h>
48#include <unistd.h>
49#include <stdlib.h>
50
51/*
52 * Code for dealing with input/output redirection.
53 */
54
55#include "shell.h"
56#include "nodes.h"
57#include "jobs.h"
58#include "expand.h"
59#include "redir.h"
60#include "output.h"
61#include "memalloc.h"
62#include "error.h"
63
64
65#define EMPTY -2		/* marks an unused slot in redirtab */
66#define PIPESIZE 4096		/* amount of buffering in a pipe */
67
68
69MKINIT
70struct redirtab {
71	struct redirtab *next;
72	short renamed[10];
73};
74
75
76MKINIT struct redirtab *redirlist;
77
78/*
79 * We keep track of whether or not fd0 has been redirected.  This is for
80 * background commands, where we want to redirect fd0 to /dev/null only
81 * if it hasn't already been redirected.
82*/
83int fd0_redirected = 0;
84
85STATIC void openredirect __P((union node *, char[10 ]));
86STATIC int openhere __P((union node *));
87
88
89/*
90 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
91 * old file descriptors are stashed away so that the redirection can be
92 * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
93 * standard output, and the standard error if it becomes a duplicate of
94 * stdout, is saved in memory.
95 */
96
97void
98redirect(redir, flags)
99	union node *redir;
100	int flags;
101	{
102	union node *n;
103	struct redirtab *sv = NULL;
104	int i;
105	int fd;
106	char memory[10];	/* file descriptors to write to memory */
107
108	for (i = 10 ; --i >= 0 ; )
109		memory[i] = 0;
110	memory[1] = flags & REDIR_BACKQ;
111	if (flags & REDIR_PUSH) {
112		sv = ckmalloc(sizeof (struct redirtab));
113		for (i = 0 ; i < 10 ; i++)
114			sv->renamed[i] = EMPTY;
115		sv->next = redirlist;
116		redirlist = sv;
117	}
118	for (n = redir ; n ; n = n->nfile.next) {
119		fd = n->nfile.fd;
120		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
121		    n->ndup.dupfd == fd)
122			continue; /* redirect from/to same file descriptor */
123		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
124			INTOFF;
125			if ((i = copyfd(fd, 10)) != EMPTY) {
126				sv->renamed[fd] = i;
127				close(fd);
128			}
129			INTON;
130			if (i == EMPTY)
131				error("Out of file descriptors");
132		} else {
133			close(fd);
134		}
135                if (fd == 0)
136                        fd0_redirected++;
137		openredirect(n, memory);
138	}
139	if (memory[1])
140		out1 = &memout;
141	if (memory[2])
142		out2 = &memout;
143}
144
145
146STATIC void
147openredirect(redir, memory)
148	union node *redir;
149	char memory[10];
150	{
151	int fd = redir->nfile.fd;
152	char *fname;
153	int f;
154
155	/*
156	 * We suppress interrupts so that we won't leave open file
157	 * descriptors around.  This may not be such a good idea because
158	 * an open of a device or a fifo can block indefinitely.
159	 */
160	INTOFF;
161	memory[fd] = 0;
162	switch (redir->nfile.type) {
163	case NFROM:
164		fname = redir->nfile.expfname;
165		if ((f = open(fname, O_RDONLY)) < 0)
166			error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
167movefd:
168		if (f != fd) {
169			copyfd(f, fd);
170			close(f);
171		}
172		break;
173	case NTO:
174		fname = redir->nfile.expfname;
175#ifdef O_CREAT
176		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
177			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
178#else
179		if ((f = creat(fname, 0666)) < 0)
180			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
181#endif
182		goto movefd;
183	case NAPPEND:
184		fname = redir->nfile.expfname;
185#ifdef O_APPEND
186		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
187			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
188#else
189		if ((f = open(fname, O_WRONLY)) < 0
190		 && (f = creat(fname, 0666)) < 0)
191			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
192		lseek(f, (off_t)0, 2);
193#endif
194		goto movefd;
195	case NTOFD:
196	case NFROMFD:
197		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
198			if (memory[redir->ndup.dupfd])
199				memory[fd] = 1;
200			else
201				copyfd(redir->ndup.dupfd, fd);
202		}
203		break;
204	case NHERE:
205	case NXHERE:
206		f = openhere(redir);
207		goto movefd;
208	default:
209		abort();
210	}
211	INTON;
212}
213
214
215/*
216 * Handle here documents.  Normally we fork off a process to write the
217 * data to a pipe.  If the document is short, we can stuff the data in
218 * the pipe without forking.
219 */
220
221STATIC int
222openhere(redir)
223	union node *redir;
224	{
225	int pip[2];
226	int len = 0;
227
228	if (pipe(pip) < 0)
229		error("Pipe call failed");
230	if (redir->type == NHERE) {
231		len = strlen(redir->nhere.doc->narg.text);
232		if (len <= PIPESIZE) {
233			xwrite(pip[1], redir->nhere.doc->narg.text, len);
234			goto out;
235		}
236	}
237	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
238		close(pip[0]);
239		signal(SIGINT, SIG_IGN);
240		signal(SIGQUIT, SIG_IGN);
241		signal(SIGHUP, SIG_IGN);
242#ifdef SIGTSTP
243		signal(SIGTSTP, SIG_IGN);
244#endif
245		signal(SIGPIPE, SIG_DFL);
246		if (redir->type == NHERE)
247			xwrite(pip[1], redir->nhere.doc->narg.text, len);
248		else
249			expandhere(redir->nhere.doc, pip[1]);
250		_exit(0);
251	}
252out:
253	close(pip[1]);
254	return pip[0];
255}
256
257
258
259/*
260 * Undo the effects of the last redirection.
261 */
262
263void
264popredir() {
265	register struct redirtab *rp = redirlist;
266	int i;
267
268	for (i = 0 ; i < 10 ; i++) {
269		if (rp->renamed[i] != EMPTY) {
270                        if (i == 0)
271                                fd0_redirected--;
272			close(i);
273			if (rp->renamed[i] >= 0) {
274				copyfd(rp->renamed[i], i);
275				close(rp->renamed[i]);
276			}
277		}
278	}
279	INTOFF;
280	redirlist = rp->next;
281	ckfree(rp);
282	INTON;
283}
284
285/*
286 * Undo all redirections.  Called on error or interrupt.
287 */
288
289#ifdef mkinit
290
291INCLUDE "redir.h"
292
293RESET {
294	while (redirlist)
295		popredir();
296}
297
298SHELLPROC {
299	clearredir();
300}
301
302#endif
303
304/* Return true if fd 0 has already been redirected at least once.  */
305int
306fd0_redirected_p () {
307        return fd0_redirected != 0;
308}
309
310/*
311 * Discard all saved file descriptors.
312 */
313
314void
315clearredir() {
316	register struct redirtab *rp;
317	int i;
318
319	for (rp = redirlist ; rp ; rp = rp->next) {
320		for (i = 0 ; i < 10 ; i++) {
321			if (rp->renamed[i] >= 0) {
322				close(rp->renamed[i]);
323			}
324			rp->renamed[i] = EMPTY;
325		}
326	}
327}
328
329
330
331/*
332 * Copy a file descriptor to be >= to.  Returns -1
333 * if the source file descriptor is closed, EMPTY if there are no unused
334 * file descriptors left.
335 */
336
337int
338copyfd(from, to)
339	int from;
340	int to;
341{
342	int newfd;
343
344	newfd = fcntl(from, F_DUPFD, to);
345	if (newfd < 0) {
346		if (errno == EMFILE)
347			return EMPTY;
348		else
349			error("%d: %s", from, strerror(errno));
350	}
351	return newfd;
352}
353