1/*	$NetBSD: redir.c,v 1.32 2011/08/31 16:24:55 plunky Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Kenneth Almquist.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
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.
21 *
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
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
39#else
40__RCSID("$NetBSD: redir.c,v 1.32 2011/08/31 16:24:55 plunky Exp $");
41#endif
42#endif /* not lint */
43
44#include <sys/types.h>
45#include <sys/param.h>	/* PIPE_BUF */
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 "main.h"
58#include "shell.h"
59#include "nodes.h"
60#include "jobs.h"
61#include "options.h"
62#include "expand.h"
63#include "redir.h"
64#include "output.h"
65#include "memalloc.h"
66#include "error.h"
67
68
69#define EMPTY -2		/* marks an unused slot in redirtab */
70#ifndef PIPE_BUF
71# define PIPESIZE 4096		/* amount of buffering in a pipe */
72#else
73# define PIPESIZE PIPE_BUF
74#endif
75
76
77MKINIT
78struct redirtab {
79	struct redirtab *next;
80	short renamed[10];
81};
82
83
84MKINIT struct redirtab *redirlist;
85
86/*
87 * We keep track of whether or not fd0 has been redirected.  This is for
88 * background commands, where we want to redirect fd0 to /dev/null only
89 * if it hasn't already been redirected.
90*/
91int fd0_redirected = 0;
92
93STATIC void openredirect(union node *, char[10], int);
94STATIC int openhere(union node *);
95
96
97/*
98 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
99 * old file descriptors are stashed away so that the redirection can be
100 * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
101 * standard output, and the standard error if it becomes a duplicate of
102 * stdout, is saved in memory.
103 */
104
105void
106redirect(union node *redir, int flags)
107{
108	union node *n;
109	struct redirtab *sv = NULL;
110	int i;
111	int fd;
112	int try;
113	char memory[10];	/* file descriptors to write to memory */
114
115	for (i = 10 ; --i >= 0 ; )
116		memory[i] = 0;
117	memory[1] = flags & REDIR_BACKQ;
118	if (flags & REDIR_PUSH) {
119		/* We don't have to worry about REDIR_VFORK here, as
120		 * flags & REDIR_PUSH is never true if REDIR_VFORK is set.
121		 */
122		sv = ckmalloc(sizeof (struct redirtab));
123		for (i = 0 ; i < 10 ; i++)
124			sv->renamed[i] = EMPTY;
125		sv->next = redirlist;
126		redirlist = sv;
127	}
128	for (n = redir ; n ; n = n->nfile.next) {
129		fd = n->nfile.fd;
130		try = 0;
131		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
132		    n->ndup.dupfd == fd)
133			continue; /* redirect from/to same file descriptor */
134
135		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
136			INTOFF;
137again:
138			if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
139				switch (errno) {
140				case EBADF:
141					if (!try) {
142						openredirect(n, memory, flags);
143						try++;
144						goto again;
145					}
146					/* FALLTHROUGH*/
147				default:
148					INTON;
149					error("%d: %s", fd, strerror(errno));
150					/* NOTREACHED */
151				}
152			}
153			if (!try) {
154				sv->renamed[fd] = i;
155				close(fd);
156			}
157			INTON;
158		} else {
159			close(fd);
160		}
161                if (fd == 0)
162                        fd0_redirected++;
163		if (!try)
164			openredirect(n, memory, flags);
165	}
166	if (memory[1])
167		out1 = &memout;
168	if (memory[2])
169		out2 = &memout;
170}
171
172
173STATIC void
174openredirect(union node *redir, char memory[10], int flags)
175{
176	int fd = redir->nfile.fd;
177	char *fname;
178	int f;
179	int oflags = O_WRONLY|O_CREAT|O_TRUNC, eflags;
180
181	/*
182	 * We suppress interrupts so that we won't leave open file
183	 * descriptors around.  This may not be such a good idea because
184	 * an open of a device or a fifo can block indefinitely.
185	 */
186	INTOFF;
187	memory[fd] = 0;
188	switch (redir->nfile.type) {
189	case NFROM:
190		fname = redir->nfile.expfname;
191		if (flags & REDIR_VFORK)
192			eflags = O_NONBLOCK;
193		else
194			eflags = 0;
195		if ((f = open(fname, O_RDONLY|eflags)) < 0)
196			goto eopen;
197		if (eflags)
198			(void)fcntl(f, F_SETFL, fcntl(f, F_GETFL, 0) & ~eflags);
199		break;
200	case NFROMTO:
201		fname = redir->nfile.expfname;
202		if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
203			goto ecreate;
204		break;
205	case NTO:
206		if (Cflag)
207			oflags |= O_EXCL;
208		/* FALLTHROUGH */
209	case NCLOBBER:
210		fname = redir->nfile.expfname;
211		if ((f = open(fname, oflags, 0666)) < 0)
212			goto ecreate;
213		break;
214	case NAPPEND:
215		fname = redir->nfile.expfname;
216		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
217			goto ecreate;
218		break;
219	case NTOFD:
220	case NFROMFD:
221		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
222			if (memory[redir->ndup.dupfd])
223				memory[fd] = 1;
224			else
225				copyfd(redir->ndup.dupfd, fd, 1);
226		}
227		INTON;
228		return;
229	case NHERE:
230	case NXHERE:
231		f = openhere(redir);
232		break;
233	default:
234		abort();
235	}
236
237	if (f != fd) {
238		copyfd(f, fd, 1);
239		close(f);
240	}
241	INTON;
242	return;
243ecreate:
244	exerrno = 1;
245	error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
246eopen:
247	exerrno = 1;
248	error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
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");
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(NULL, 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, 1);
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(0);
337}
338
339#endif
340
341/* Return true if fd 0 has already been redirected at least once.  */
342int
343fd0_redirected_p () {
344        return fd0_redirected != 0;
345}
346
347/*
348 * Discard all saved file descriptors.
349 */
350
351void
352clearredir(vforked)
353	int vforked;
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			if (!vforked)
364				rp->renamed[i] = EMPTY;
365		}
366	}
367}
368
369
370
371/*
372 * Copy a file descriptor to be >= to.  Returns -1
373 * if the source file descriptor is closed, EMPTY if there are no unused
374 * file descriptors left.
375 */
376
377int
378copyfd(int from, int to, int equal)
379{
380	int newfd;
381
382	if (equal)
383		newfd = dup2(from, to);
384	else
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