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 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34#if 0
35static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD$");
40
41#include <sys/types.h>
42#include <sys/stat.h>
43#include <signal.h>
44#include <string.h>
45#include <fcntl.h>
46#include <errno.h>
47#include <unistd.h>
48#include <stdlib.h>
49
50/*
51 * Code for dealing with input/output redirection.
52 */
53
54#include "shell.h"
55#include "nodes.h"
56#include "jobs.h"
57#include "expand.h"
58#include "redir.h"
59#include "output.h"
60#include "memalloc.h"
61#include "error.h"
62#include "options.h"
63
64
65#define EMPTY -2		/* marks an unused slot in redirtab */
66#define CLOSED -1		/* fd was not open before redir */
67#define PIPESIZE 4096		/* amount of buffering in a pipe */
68
69
70MKINIT
71struct redirtab {
72	struct redirtab *next;
73	int renamed[10];
74};
75
76
77MKINIT struct redirtab *redirlist;
78
79/*
80 * We keep track of whether or not fd0 has been redirected.  This is for
81 * background commands, where we want to redirect fd0 to /dev/null only
82 * if it hasn't already been redirected.
83*/
84static int fd0_redirected = 0;
85
86static void openredirect(union node *, char[10 ]);
87static int openhere(union node *);
88
89
90/*
91 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
92 * old file descriptors are stashed away so that the redirection can be
93 * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
94 * standard output, and the standard error if it becomes a duplicate of
95 * stdout, is saved in memory.
96*
97 * We suppress interrupts so that we won't leave open file
98 * descriptors around.  Because the signal handler remains
99 * installed and we do not use system call restart, interrupts
100 * will still abort blocking opens such as fifos (they will fail
101 * with EINTR). There is, however, a race condition if an interrupt
102 * arrives after INTOFF and before open blocks.
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	char memory[10];	/* file descriptors to write to memory */
113
114	INTOFF;
115	for (i = 10 ; --i >= 0 ; )
116		memory[i] = 0;
117	memory[1] = flags & REDIR_BACKQ;
118	if (flags & REDIR_PUSH) {
119		sv = ckmalloc(sizeof (struct redirtab));
120		for (i = 0 ; i < 10 ; i++)
121			sv->renamed[i] = EMPTY;
122		sv->next = redirlist;
123		redirlist = sv;
124	}
125	for (n = redir ; n ; n = n->nfile.next) {
126		fd = n->nfile.fd;
127		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
128		    n->ndup.dupfd == fd)
129			continue; /* redirect from/to same file descriptor */
130
131		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
132			INTOFF;
133			if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
134				switch (errno) {
135				case EBADF:
136					i = CLOSED;
137					break;
138				default:
139					INTON;
140					error("%d: %s", fd, strerror(errno));
141					break;
142				}
143			} else
144				(void)fcntl(i, F_SETFD, FD_CLOEXEC);
145			sv->renamed[fd] = i;
146			INTON;
147		}
148		if (fd == 0)
149			fd0_redirected++;
150		openredirect(n, memory);
151		INTON;
152		INTOFF;
153	}
154	if (memory[1])
155		out1 = &memout;
156	if (memory[2])
157		out2 = &memout;
158	INTON;
159}
160
161
162static void
163openredirect(union node *redir, char memory[10])
164{
165	struct stat sb;
166	int fd = redir->nfile.fd;
167	char *fname;
168	int f;
169	int e;
170
171	memory[fd] = 0;
172	switch (redir->nfile.type) {
173	case NFROM:
174		fname = redir->nfile.expfname;
175		if ((f = open(fname, O_RDONLY)) < 0)
176			error("cannot open %s: %s", fname, strerror(errno));
177movefd:
178		if (f != fd) {
179			if (dup2(f, fd) == -1) {
180				e = errno;
181				close(f);
182				error("%d: %s", fd, strerror(e));
183			}
184			close(f);
185		}
186		break;
187	case NFROMTO:
188		fname = redir->nfile.expfname;
189		if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
190			error("cannot create %s: %s", fname, strerror(errno));
191		goto movefd;
192	case NTO:
193		if (Cflag) {
194			fname = redir->nfile.expfname;
195			if (stat(fname, &sb) == -1) {
196				if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
197					error("cannot create %s: %s", fname, strerror(errno));
198			} else if (!S_ISREG(sb.st_mode)) {
199				if ((f = open(fname, O_WRONLY, 0666)) < 0)
200					error("cannot create %s: %s", fname, strerror(errno));
201				if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
202					close(f);
203					error("cannot create %s: %s", fname,
204					    strerror(EEXIST));
205				}
206			} else
207				error("cannot create %s: %s", fname,
208				    strerror(EEXIST));
209			goto movefd;
210		}
211		/* FALLTHROUGH */
212	case NCLOBBER:
213		fname = redir->nfile.expfname;
214		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
215			error("cannot create %s: %s", fname, strerror(errno));
216		goto movefd;
217	case NAPPEND:
218		fname = redir->nfile.expfname;
219		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
220			error("cannot create %s: %s", fname, strerror(errno));
221		goto movefd;
222	case NTOFD:
223	case NFROMFD:
224		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
225			if (memory[redir->ndup.dupfd])
226				memory[fd] = 1;
227			else {
228				if (dup2(redir->ndup.dupfd, fd) < 0)
229					error("%d: %s", redir->ndup.dupfd,
230							strerror(errno));
231			}
232		} else {
233			close(fd);
234		}
235		break;
236	case NHERE:
237	case NXHERE:
238		f = openhere(redir);
239		goto movefd;
240	default:
241		abort();
242	}
243}
244
245
246/*
247 * Handle here documents.  Normally we fork off a process to write the
248 * data to a pipe.  If the document is short, we can stuff the data in
249 * the pipe without forking.
250 */
251
252static int
253openhere(union node *redir)
254{
255	int pip[2];
256	int len = 0;
257
258	if (pipe(pip) < 0)
259		error("Pipe call failed: %s", strerror(errno));
260	if (redir->type == NHERE) {
261		len = strlen(redir->nhere.doc->narg.text);
262		if (len <= PIPESIZE) {
263			xwrite(pip[1], redir->nhere.doc->narg.text, len);
264			goto out;
265		}
266	}
267	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
268		close(pip[0]);
269		signal(SIGINT, SIG_IGN);
270		signal(SIGQUIT, SIG_IGN);
271		signal(SIGHUP, SIG_IGN);
272		signal(SIGTSTP, SIG_IGN);
273		signal(SIGPIPE, SIG_DFL);
274		if (redir->type == NHERE)
275			xwrite(pip[1], redir->nhere.doc->narg.text, len);
276		else
277			expandhere(redir->nhere.doc, pip[1]);
278		_exit(0);
279	}
280out:
281	close(pip[1]);
282	return pip[0];
283}
284
285
286
287/*
288 * Undo the effects of the last redirection.
289 */
290
291void
292popredir(void)
293{
294	struct redirtab *rp = redirlist;
295	int i;
296
297	for (i = 0 ; i < 10 ; i++) {
298		if (rp->renamed[i] != EMPTY) {
299                        if (i == 0)
300                                fd0_redirected--;
301			if (rp->renamed[i] >= 0) {
302				dup2(rp->renamed[i], i);
303				close(rp->renamed[i]);
304			} else {
305				close(i);
306			}
307		}
308	}
309	INTOFF;
310	redirlist = rp->next;
311	ckfree(rp);
312	INTON;
313}
314
315/*
316 * Undo all redirections.  Called on error or interrupt.
317 */
318
319#ifdef mkinit
320
321INCLUDE "redir.h"
322
323RESET {
324	while (redirlist)
325		popredir();
326}
327
328#endif
329
330/* Return true if fd 0 has already been redirected at least once.  */
331int
332fd0_redirected_p(void)
333{
334        return fd0_redirected != 0;
335}
336
337/*
338 * Discard all saved file descriptors.
339 */
340
341void
342clearredir(void)
343{
344	struct redirtab *rp;
345	int i;
346
347	for (rp = redirlist ; rp ; rp = rp->next) {
348		for (i = 0 ; i < 10 ; i++) {
349			if (rp->renamed[i] >= 0) {
350				close(rp->renamed[i]);
351			}
352			rp->renamed[i] = EMPTY;
353		}
354	}
355}
356