redir.c revision 88463 
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 88463 2001-12-24 22:27:04Z alfred $";
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 NFROMTO:
194		fname = redir->nfile.expfname;
195#ifdef O_CREAT
196		if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
197			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
198#else
199		if ((f = open(fname, O_RDWR, 0666)) < 0) {
200			if (errno != ENOENT)
201				error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
202			else if ((f = creat(fname, 0666)) < 0)
203				error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
204			else {
205				close(f);
206				if ((f = open(fname, O_RDWR)) < 0) {
207					error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
208					remove(fname);
209				}
210			}
211		}
212#endif
213		goto movefd;
214	case NTO:
215		fname = redir->nfile.expfname;
216#ifdef O_CREAT
217		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
218			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
219#else
220		if ((f = creat(fname, 0666)) < 0)
221			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
222#endif
223		goto movefd;
224	case NAPPEND:
225		fname = redir->nfile.expfname;
226#ifdef O_APPEND
227		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
228			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
229#else
230		if ((f = open(fname, O_WRONLY)) < 0
231		 && (f = creat(fname, 0666)) < 0)
232			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
233		lseek(f, (off_t)0, 2);
234#endif
235		goto movefd;
236	case NTOFD:
237	case NFROMFD:
238		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
239			if (memory[redir->ndup.dupfd])
240				memory[fd] = 1;
241			else
242				copyfd(redir->ndup.dupfd, fd);
243		}
244		break;
245	case NHERE:
246	case NXHERE:
247		f = openhere(redir);
248		goto movefd;
249	default:
250		abort();
251	}
252	INTON;
253}
254
255
256/*
257 * Handle here documents.  Normally we fork off a process to write the
258 * data to a pipe.  If the document is short, we can stuff the data in
259 * the pipe without forking.
260 */
261
262STATIC int
263openhere(redir)
264	union node *redir;
265	{
266	int pip[2];
267	int len = 0;
268
269	if (pipe(pip) < 0)
270		error("Pipe call failed: %s", strerror(errno));
271	if (redir->type == NHERE) {
272		len = strlen(redir->nhere.doc->narg.text);
273		if (len <= PIPESIZE) {
274			xwrite(pip[1], redir->nhere.doc->narg.text, len);
275			goto out;
276		}
277	}
278	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
279		close(pip[0]);
280		signal(SIGINT, SIG_IGN);
281		signal(SIGQUIT, SIG_IGN);
282		signal(SIGHUP, SIG_IGN);
283#ifdef SIGTSTP
284		signal(SIGTSTP, SIG_IGN);
285#endif
286		signal(SIGPIPE, SIG_DFL);
287		if (redir->type == NHERE)
288			xwrite(pip[1], redir->nhere.doc->narg.text, len);
289		else
290			expandhere(redir->nhere.doc, pip[1]);
291		_exit(0);
292	}
293out:
294	close(pip[1]);
295	return pip[0];
296}
297
298
299
300/*
301 * Undo the effects of the last redirection.
302 */
303
304void
305popredir() {
306	struct redirtab *rp = redirlist;
307	int i;
308
309	for (i = 0 ; i < 10 ; i++) {
310		if (rp->renamed[i] != EMPTY) {
311                        if (i == 0)
312                                fd0_redirected--;
313			close(i);
314			if (rp->renamed[i] >= 0) {
315				copyfd(rp->renamed[i], i);
316				close(rp->renamed[i]);
317			}
318		}
319	}
320	INTOFF;
321	redirlist = rp->next;
322	ckfree(rp);
323	INTON;
324}
325
326/*
327 * Undo all redirections.  Called on error or interrupt.
328 */
329
330#ifdef mkinit
331
332INCLUDE "redir.h"
333
334RESET {
335	while (redirlist)
336		popredir();
337}
338
339SHELLPROC {
340	clearredir();
341}
342
343#endif
344
345/* Return true if fd 0 has already been redirected at least once.  */
346int
347fd0_redirected_p () {
348        return fd0_redirected != 0;
349}
350
351/*
352 * Discard all saved file descriptors.
353 */
354
355void
356clearredir() {
357	struct redirtab *rp;
358	int i;
359
360	for (rp = redirlist ; rp ; rp = rp->next) {
361		for (i = 0 ; i < 10 ; i++) {
362			if (rp->renamed[i] >= 0) {
363				close(rp->renamed[i]);
364			}
365			rp->renamed[i] = EMPTY;
366		}
367	}
368}
369
370
371
372/*
373 * Copy a file descriptor to be >= to.  Returns -1
374 * if the source file descriptor is closed, EMPTY if there are no unused
375 * file descriptors left.
376 */
377
378int
379copyfd(from, to)
380	int from;
381	int to;
382{
383	int newfd;
384
385	newfd = fcntl(from, F_DUPFD, to);
386	if (newfd < 0) {
387		if (errno == EMFILE)
388			return EMPTY;
389		else
390			error("%d: %s", from, strerror(errno));
391	}
392	return newfd;
393}
394