redir.c revision 90111 
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  "$FreeBSD: head/bin/sh/redir.c 90111 2002-02-02 06:50:57Z imp $";
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(union node *, char[10 ]);
88STATIC int openhere(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(union node *redir, int flags)
101{
102	union node *n;
103	struct redirtab *sv = NULL;
104	int i;
105	int fd;
106	int try;
107	char memory[10];	/* file descriptors to write to memory */
108
109	for (i = 10 ; --i >= 0 ; )
110		memory[i] = 0;
111	memory[1] = flags & REDIR_BACKQ;
112	if (flags & REDIR_PUSH) {
113		sv = ckmalloc(sizeof (struct redirtab));
114		for (i = 0 ; i < 10 ; i++)
115			sv->renamed[i] = EMPTY;
116		sv->next = redirlist;
117		redirlist = sv;
118	}
119	for (n = redir ; n ; n = n->nfile.next) {
120		fd = n->nfile.fd;
121		try = 0;
122		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
123		    n->ndup.dupfd == fd)
124			continue; /* redirect from/to same file descriptor */
125
126		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
127			INTOFF;
128again:
129			if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
130				switch (errno) {
131				case EBADF:
132					if (!try) {
133						openredirect(n, memory);
134						try++;
135						goto again;
136					}
137					/* FALLTHROUGH*/
138				default:
139					INTON;
140					error("%d: %s", fd, strerror(errno));
141					break;
142				}
143			}
144			if (!try) {
145				sv->renamed[fd] = i;
146			}
147			INTON;
148		}
149		if (fd == 0)
150			fd0_redirected++;
151		if (!try)
152			openredirect(n, memory);
153	}
154	if (memory[1])
155		out1 = &memout;
156	if (memory[2])
157		out2 = &memout;
158}
159
160
161STATIC void
162openredirect(union node *redir, char memory[10])
163{
164	int fd = redir->nfile.fd;
165	char *fname;
166	int f;
167
168	/*
169	 * We suppress interrupts so that we won't leave open file
170	 * descriptors around.  This may not be such a good idea because
171	 * an open of a device or a fifo can block indefinitely.
172	 */
173	INTOFF;
174	memory[fd] = 0;
175	switch (redir->nfile.type) {
176	case NFROM:
177		fname = redir->nfile.expfname;
178		if ((f = open(fname, O_RDONLY)) < 0)
179			error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
180movefd:
181		if (f != fd) {
182			close(fd);
183			copyfd(f, fd);
184			close(f);
185		}
186		break;
187	case NFROMTO:
188		fname = redir->nfile.expfname;
189#ifdef O_CREAT
190		if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
191			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
192#else
193		if ((f = open(fname, O_RDWR, 0666)) < 0) {
194			if (errno != ENOENT)
195				error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
196			else if ((f = creat(fname, 0666)) < 0)
197				error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
198			else {
199				close(f);
200				if ((f = open(fname, O_RDWR)) < 0) {
201					error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
202					remove(fname);
203				}
204			}
205		}
206#endif
207		goto movefd;
208	case NTO:
209		fname = redir->nfile.expfname;
210#ifdef O_CREAT
211		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
212			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
213#else
214		if ((f = creat(fname, 0666)) < 0)
215			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
216#endif
217		goto movefd;
218	case NAPPEND:
219		fname = redir->nfile.expfname;
220#ifdef O_APPEND
221		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
222			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
223#else
224		if ((f = open(fname, O_WRONLY)) < 0
225		 && (f = creat(fname, 0666)) < 0)
226			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
227		lseek(f, (off_t)0, 2);
228#endif
229		goto movefd;
230	case NTOFD:
231	case NFROMFD:
232		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
233			if (memory[redir->ndup.dupfd])
234				memory[fd] = 1;
235			else {
236				close(fd);
237				copyfd(redir->ndup.dupfd, fd);
238			}
239		}
240		break;
241	case NHERE:
242	case NXHERE:
243		f = openhere(redir);
244		goto movefd;
245	default:
246		abort();
247	}
248	INTON;
249}
250
251
252/*
253 * Handle here documents.  Normally we fork off a process to write the
254 * data to a pipe.  If the document is short, we can stuff the data in
255 * the pipe without forking.
256 */
257
258STATIC int
259openhere(union node *redir)
260{
261	int pip[2];
262	int len = 0;
263
264	if (pipe(pip) < 0)
265		error("Pipe call failed: %s", strerror(errno));
266	if (redir->type == NHERE) {
267		len = strlen(redir->nhere.doc->narg.text);
268		if (len <= PIPESIZE) {
269			xwrite(pip[1], redir->nhere.doc->narg.text, len);
270			goto out;
271		}
272	}
273	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
274		close(pip[0]);
275		signal(SIGINT, SIG_IGN);
276		signal(SIGQUIT, SIG_IGN);
277		signal(SIGHUP, SIG_IGN);
278#ifdef SIGTSTP
279		signal(SIGTSTP, SIG_IGN);
280#endif
281		signal(SIGPIPE, SIG_DFL);
282		if (redir->type == NHERE)
283			xwrite(pip[1], redir->nhere.doc->narg.text, len);
284		else
285			expandhere(redir->nhere.doc, pip[1]);
286		_exit(0);
287	}
288out:
289	close(pip[1]);
290	return pip[0];
291}
292
293
294
295/*
296 * Undo the effects of the last redirection.
297 */
298
299void
300popredir(void)
301{
302	struct redirtab *rp = redirlist;
303	int i;
304
305	for (i = 0 ; i < 10 ; i++) {
306		if (rp->renamed[i] != EMPTY) {
307                        if (i == 0)
308                                fd0_redirected--;
309			close(i);
310			if (rp->renamed[i] >= 0) {
311				copyfd(rp->renamed[i], i);
312				close(rp->renamed[i]);
313			}
314		}
315	}
316	INTOFF;
317	redirlist = rp->next;
318	ckfree(rp);
319	INTON;
320}
321
322/*
323 * Undo all redirections.  Called on error or interrupt.
324 */
325
326#ifdef mkinit
327
328INCLUDE "redir.h"
329
330RESET {
331	while (redirlist)
332		popredir();
333}
334
335SHELLPROC {
336	clearredir();
337}
338
339#endif
340
341/* Return true if fd 0 has already been redirected at least once.  */
342int
343fd0_redirected_p(void)
344{
345        return fd0_redirected != 0;
346}
347
348/*
349 * Discard all saved file descriptors.
350 */
351
352void
353clearredir(void)
354{
355	struct redirtab *rp;
356	int i;
357
358	for (rp = redirlist ; rp ; rp = rp->next) {
359		for (i = 0 ; i < 10 ; i++) {
360			if (rp->renamed[i] >= 0) {
361				close(rp->renamed[i]);
362			}
363			rp->renamed[i] = EMPTY;
364		}
365	}
366}
367
368
369
370/*
371 * Copy a file descriptor to be >= to.  Returns -1
372 * if the source file descriptor is closed, EMPTY if there are no unused
373 * file descriptors left.
374 */
375
376int
377copyfd(int from, int to)
378{
379	int newfd;
380
381	newfd = fcntl(from, F_DUPFD, to);
382	if (newfd < 0) {
383		if (errno == EMFILE)
384			return EMPTY;
385		else
386			error("%d: %s", from, strerror(errno));
387	}
388	return newfd;
389}
390