redir.c revision 36150 
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
37#ifndef lint
38#if 0
39static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
40#endif
41static const char rcsid[] =
42	"$Id$";
43#endif /* not lint */
44
45#include <sys/types.h>
46#include <signal.h>
47#include <string.h>
48#include <fcntl.h>
49#include <errno.h>
50#include <unistd.h>
51#include <stdlib.h>
52
53/*
54 * Code for dealing with input/output redirection.
55 */
56
57#include "shell.h"
58#include "nodes.h"
59#include "jobs.h"
60#include "expand.h"
61#include "redir.h"
62#include "output.h"
63#include "memalloc.h"
64#include "error.h"
65
66
67#define EMPTY -2		/* marks an unused slot in redirtab */
68#define PIPESIZE 4096		/* amount of buffering in a pipe */
69
70
71MKINIT
72struct redirtab {
73	struct redirtab *next;
74	short renamed[10];
75};
76
77
78MKINIT struct redirtab *redirlist;
79
80/*
81 * We keep track of whether or not fd0 has been redirected.  This is for
82 * background commands, where we want to redirect fd0 to /dev/null only
83 * if it hasn't already been redirected.
84*/
85int fd0_redirected = 0;
86
87STATIC void openredirect __P((union node *, char[10 ]));
88STATIC int openhere __P((union node *));
89
90
91/*
92 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
93 * old file descriptors are stashed away so that the redirection can be
94 * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
95 * standard output, and the standard error if it becomes a duplicate of
96 * stdout, is saved in memory.
97 */
98
99void
100redirect(redir, flags)
101	union node *redir;
102	int flags;
103	{
104	union node *n;
105	struct redirtab *sv = NULL;
106	int i;
107	int fd;
108	int try;
109	char memory[10];	/* file descriptors to write to memory */
110
111	for (i = 10 ; --i >= 0 ; )
112		memory[i] = 0;
113	memory[1] = flags & REDIR_BACKQ;
114	if (flags & REDIR_PUSH) {
115		sv = ckmalloc(sizeof (struct redirtab));
116		for (i = 0 ; i < 10 ; i++)
117			sv->renamed[i] = EMPTY;
118		sv->next = redirlist;
119		redirlist = sv;
120	}
121	for (n = redir ; n ; n = n->nfile.next) {
122		fd = n->nfile.fd;
123		try = 0;
124		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
125		    n->ndup.dupfd == fd)
126			continue; /* redirect from/to same file descriptor */
127
128		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
129			INTOFF;
130again:
131			if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
132				switch (errno) {
133				case EBADF:
134					if (!try) {
135						openredirect(n, memory);
136						try++;
137						goto again;
138					}
139					/* FALLTHROUGH*/
140				default:
141					INTON;
142					error("%d: %s", fd, strerror(errno));
143					break;
144				}
145			}
146			if (!try) {
147				sv->renamed[fd] = i;
148				close(fd);
149			}
150			INTON;
151		} else {
152			close(fd);
153		}
154		if (fd == 0)
155			fd0_redirected++;
156		if (!try)
157			openredirect(n, memory);
158	}
159	if (memory[1])
160		out1 = &memout;
161	if (memory[2])
162		out2 = &memout;
163}
164
165
166STATIC void
167openredirect(redir, memory)
168	union node *redir;
169	char memory[10];
170	{
171	int fd = redir->nfile.fd;
172	char *fname;
173	int f;
174
175	/*
176	 * We suppress interrupts so that we won't leave open file
177	 * descriptors around.  This may not be such a good idea because
178	 * an open of a device or a fifo can block indefinitely.
179	 */
180	INTOFF;
181	memory[fd] = 0;
182	switch (redir->nfile.type) {
183	case NFROM:
184		fname = redir->nfile.expfname;
185		if ((f = open(fname, O_RDONLY)) < 0)
186			error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
187movefd:
188		if (f != fd) {
189			copyfd(f, fd);
190			close(f);
191		}
192		break;
193	case NTO:
194		fname = redir->nfile.expfname;
195#ifdef O_CREAT
196		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
197			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
198#else
199		if ((f = creat(fname, 0666)) < 0)
200			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
201#endif
202		goto movefd;
203	case NAPPEND:
204		fname = redir->nfile.expfname;
205#ifdef O_APPEND
206		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
207			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
208#else
209		if ((f = open(fname, O_WRONLY)) < 0
210		 && (f = creat(fname, 0666)) < 0)
211			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
212		lseek(f, (off_t)0, 2);
213#endif
214		goto movefd;
215	case NTOFD:
216	case NFROMFD:
217		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
218			if (memory[redir->ndup.dupfd])
219				memory[fd] = 1;
220			else
221				copyfd(redir->ndup.dupfd, fd);
222		}
223		break;
224	case NHERE:
225	case NXHERE:
226		f = openhere(redir);
227		goto movefd;
228	default:
229		abort();
230	}
231	INTON;
232}
233
234
235/*
236 * Handle here documents.  Normally we fork off a process to write the
237 * data to a pipe.  If the document is short, we can stuff the data in
238 * the pipe without forking.
239 */
240
241STATIC int
242openhere(redir)
243	union node *redir;
244	{
245	int pip[2];
246	int len = 0;
247
248	if (pipe(pip) < 0)
249		error("Pipe call failed");
250	if (redir->type == NHERE) {
251		len = strlen(redir->nhere.doc->narg.text);
252		if (len <= PIPESIZE) {
253			xwrite(pip[1], redir->nhere.doc->narg.text, len);
254			goto out;
255		}
256	}
257	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
258		close(pip[0]);
259		signal(SIGINT, SIG_IGN);
260		signal(SIGQUIT, SIG_IGN);
261		signal(SIGHUP, SIG_IGN);
262#ifdef SIGTSTP
263		signal(SIGTSTP, SIG_IGN);
264#endif
265		signal(SIGPIPE, SIG_DFL);
266		if (redir->type == NHERE)
267			xwrite(pip[1], redir->nhere.doc->narg.text, len);
268		else
269			expandhere(redir->nhere.doc, pip[1]);
270		_exit(0);
271	}
272out:
273	close(pip[1]);
274	return pip[0];
275}
276
277
278
279/*
280 * Undo the effects of the last redirection.
281 */
282
283void
284popredir() {
285	struct redirtab *rp = redirlist;
286	int i;
287
288	for (i = 0 ; i < 10 ; i++) {
289		if (rp->renamed[i] != EMPTY) {
290                        if (i == 0)
291                                fd0_redirected--;
292			close(i);
293			if (rp->renamed[i] >= 0) {
294				copyfd(rp->renamed[i], i);
295				close(rp->renamed[i]);
296			}
297		}
298	}
299	INTOFF;
300	redirlist = rp->next;
301	ckfree(rp);
302	INTON;
303}
304
305/*
306 * Undo all redirections.  Called on error or interrupt.
307 */
308
309#ifdef mkinit
310
311INCLUDE "redir.h"
312
313RESET {
314	while (redirlist)
315		popredir();
316}
317
318SHELLPROC {
319	clearredir();
320}
321
322#endif
323
324/* Return true if fd 0 has already been redirected at least once.  */
325int
326fd0_redirected_p () {
327        return fd0_redirected != 0;
328}
329
330/*
331 * Discard all saved file descriptors.
332 */
333
334void
335clearredir() {
336	struct redirtab *rp;
337	int i;
338
339	for (rp = redirlist ; rp ; rp = rp->next) {
340		for (i = 0 ; i < 10 ; i++) {
341			if (rp->renamed[i] >= 0) {
342				close(rp->renamed[i]);
343			}
344			rp->renamed[i] = EMPTY;
345		}
346	}
347}
348
349
350
351/*
352 * Copy a file descriptor to be >= to.  Returns -1
353 * if the source file descriptor is closed, EMPTY if there are no unused
354 * file descriptors left.
355 */
356
357int
358copyfd(from, to)
359	int from;
360	int to;
361{
362	int newfd;
363
364	newfd = fcntl(from, F_DUPFD, to);
365	if (newfd < 0) {
366		if (errno == EMFILE)
367			return EMPTY;
368		else
369			error("%d: %s", from, strerror(errno));
370	}
371	return newfd;
372}
373