1/*	$NetBSD: trap.c,v 1.31 2005/01/11 19:38:57 christos 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[] = "@(#)trap.c	8.5 (Berkeley) 6/5/95";
39#else
40__RCSID("$NetBSD: trap.c,v 1.31 2005/01/11 19:38:57 christos Exp $");
41#endif
42#endif /* not lint */
43
44#include <signal.h>
45#include <unistd.h>
46#include <stdlib.h>
47
48#include "shell.h"
49#include "main.h"
50#include "nodes.h"	/* for other headers */
51#include "eval.h"
52#include "jobs.h"
53#include "show.h"
54#include "options.h"
55#include "syntax.h"
56#include "output.h"
57#include "memalloc.h"
58#include "error.h"
59#include "trap.h"
60#include "mystring.h"
61#include "var.h"
62
63/*
64 * Sigmode records the current value of the signal handlers for the various
65 * modes.  A value of zero means that the current handler is not known.
66 * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
67 */
68
69#define S_DFL 1			/* default signal handling (SIG_DFL) */
70#define S_CATCH 2		/* signal is caught */
71#define S_IGN 3			/* signal is ignored (SIG_IGN) */
72#define S_HARD_IGN 4		/* signal is ignored permenantly */
73#define S_RESET 5		/* temporary - to reset a hard ignored sig */
74
75
76char *trap[NSIG+1];		/* trap handler commands */
77MKINIT char sigmode[NSIG];	/* current value of signal */
78char gotsig[NSIG];		/* indicates specified signal received */
79int pendingsigs;		/* indicates some signal received */
80
81static int getsigaction(int, sig_t *);
82
83/*
84 * return the signal number described by `p' (as a number or a name)
85 * or -1 if it isn't one
86 */
87
88static int
89signame_to_signum(const char *p)
90{
91	int i;
92
93	if (is_number(p))
94		return number(p);
95
96	if (strcasecmp(p, "exit") == 0 )
97		return 0;
98
99	if (strncasecmp(p, "sig", 3) == 0)
100		p += 3;
101
102	for (i = 0; i < NSIG; ++i)
103		if (sys_signame[i] && (strcasecmp (p, sys_signame[i]) == 0))
104			return i;
105	return -1;
106}
107
108/*
109 * Print a list of valid signal names
110 */
111static void
112printsignals(void)
113{
114	int n;
115
116	out1str("EXIT ");
117
118	for (n = 1; n < NSIG; n++) {
119		out1fmt("%s", sys_signame[n]);
120		if ((n == NSIG/2) ||  n == (NSIG - 1))
121			out1str("\n");
122		else
123			out1c(' ');
124	}
125}
126
127/*
128 * The trap builtin.
129 */
130
131int
132trapcmd(int argc, char **argv)
133{
134	char *action;
135	char **ap;
136	int signo;
137
138	if (argc <= 1) {
139		for (signo = 0 ; signo <= NSIG ; signo++)
140			if (trap[signo] != NULL) {
141				out1fmt("trap -- ");
142				print_quoted(trap[signo]);
143				out1fmt(" %s\n",
144				    (signo) ? sys_signame[signo] : "EXIT");
145			}
146		return 0;
147	}
148	ap = argv + 1;
149
150	action = NULL;
151
152	if (strcmp(*ap, "--") == 0)
153		if (*++ap == NULL)
154			return 0;
155
156	if (signame_to_signum(*ap) == -1) {
157		if ((*ap)[0] == '-') {
158			if ((*ap)[1] == '\0')
159				ap++;
160			else if ((*ap)[1] == 'l' && (*ap)[2] == '\0') {
161				printsignals();
162				return 0;
163			}
164			else
165				error("bad option %s\n", *ap);
166		}
167		else
168			action = *ap++;
169	}
170
171	while (*ap) {
172		if (is_number(*ap))
173			signo = number(*ap);
174		else
175			signo = signame_to_signum(*ap);
176
177		if (signo < 0 || signo > NSIG)
178			error("%s: bad trap", *ap);
179
180		INTOFF;
181		if (action)
182			action = savestr(action);
183
184		if (trap[signo])
185			ckfree(trap[signo]);
186
187		trap[signo] = action;
188
189		if (signo != 0)
190			setsignal(signo, 0);
191		INTON;
192		ap++;
193	}
194	return 0;
195}
196
197
198
199/*
200 * Clear traps on a fork or vfork.
201 * Takes one arg vfork, to tell it to not be destructive of
202 * the parents variables.
203 */
204
205void
206clear_traps(int vforked)
207{
208	char **tp;
209
210	for (tp = trap ; tp <= &trap[NSIG] ; tp++) {
211		if (*tp && **tp) {	/* trap not NULL or SIG_IGN */
212			INTOFF;
213			if (!vforked) {
214				ckfree(*tp);
215				*tp = NULL;
216			}
217			if (tp != &trap[0])
218				setsignal(tp - trap, vforked);
219			INTON;
220		}
221	}
222}
223
224
225
226/*
227 * Set the signal handler for the specified signal.  The routine figures
228 * out what it should be set to.
229 */
230
231long
232setsignal(int signo, int vforked)
233{
234	int action;
235	sig_t sigact = SIG_DFL;
236	struct sigaction act, oact;
237	char *t, tsig;
238
239	if ((t = trap[signo]) == NULL)
240		action = S_DFL;
241	else if (*t != '\0')
242		action = S_CATCH;
243	else
244		action = S_IGN;
245	if (rootshell && !vforked && action == S_DFL) {
246		switch (signo) {
247		case SIGINT:
248			if (iflag || minusc || sflag == 0)
249				action = S_CATCH;
250			break;
251		case SIGQUIT:
252#ifdef DEBUG
253			if (debug)
254				break;
255#endif
256			/* FALLTHROUGH */
257		case SIGTERM:
258			if (iflag)
259				action = S_IGN;
260			break;
261#if JOBS
262		case SIGTSTP:
263		case SIGTTOU:
264			if (mflag)
265				action = S_IGN;
266			break;
267#endif
268		}
269	}
270
271	t = &sigmode[signo - 1];
272	tsig = *t;
273	if (tsig == 0) {
274		/*
275		 * current setting unknown
276		 */
277		if (!getsigaction(signo, &sigact)) {
278			/*
279			 * Pretend it worked; maybe we should give a warning
280			 * here, but other shells don't. We don't alter
281			 * sigmode, so that we retry every time.
282			 */
283			return 0;
284		}
285		if (sigact == SIG_IGN) {
286			if (mflag && (signo == SIGTSTP ||
287			     signo == SIGTTIN || signo == SIGTTOU)) {
288				tsig = S_IGN;	/* don't hard ignore these */
289			} else
290				tsig = S_HARD_IGN;
291		} else {
292			tsig = S_RESET;	/* force to be set */
293		}
294	}
295	if (tsig == S_HARD_IGN || tsig == action)
296		return 0;
297	switch (action) {
298		case S_DFL:	sigact = SIG_DFL;	break;
299		case S_CATCH:  	sigact = onsig;		break;
300		case S_IGN:	sigact = SIG_IGN;	break;
301	}
302	if (!vforked)
303		*t = action;
304    act.sa_handler = sigact;
305    sigemptyset(&act.sa_mask);
306    act.sa_flags = 0;
307#ifdef SA_INTERRUPT
308    act.sa_flags |= SA_INTERRUPT;
309#endif
310    if(sigaction(signo, &act, &oact) < 0)
311        return (long) SIG_ERR;
312    return (long) oact.sa_handler;
313}
314
315/*
316 * Return the current setting for sig w/o changing it.
317 */
318static int
319getsigaction(int signo, sig_t *sigact)
320{
321	struct sigaction sa;
322
323	if (sigaction(signo, (struct sigaction *)0, &sa) == -1)
324		return 0;
325	*sigact = (sig_t) sa.sa_handler;
326	return 1;
327}
328
329/*
330 * Ignore a signal.
331 */
332
333void
334ignoresig(int signo, int vforked)
335{
336	if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN)
337		bsd_signal(signo, SIG_IGN);
338	if (!vforked)
339		sigmode[signo - 1] = S_HARD_IGN;
340}
341
342
343#ifdef mkinit
344INCLUDE <signal.h>
345INCLUDE "trap.h"
346
347SHELLPROC {
348	char *sm;
349
350	clear_traps(0);
351	for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
352		if (*sm == S_IGN)
353			*sm = S_HARD_IGN;
354	}
355}
356#endif
357
358
359
360/*
361 * Signal handler.
362 */
363
364void
365onsig(int signo)
366{
367	bsd_signal(signo, onsig);
368	if (signo == SIGINT && trap[SIGINT] == NULL) {
369		onint();
370		return;
371	}
372	gotsig[signo - 1] = 1;
373	pendingsigs++;
374}
375
376
377
378/*
379 * Called to execute a trap.  Perhaps we should avoid entering new trap
380 * handlers while we are executing a trap handler.
381 */
382
383void
384dotrap(void)
385{
386	int i;
387	int savestatus;
388
389	for (;;) {
390		for (i = 1 ; ; i++) {
391			if (gotsig[i - 1])
392				break;
393			if (i >= NSIG)
394				goto done;
395		}
396		gotsig[i - 1] = 0;
397		savestatus=exitstatus;
398		evalstring(trap[i], 0);
399		exitstatus=savestatus;
400	}
401done:
402	pendingsigs = 0;
403}
404
405
406
407/*
408 * Controls whether the shell is interactive or not.
409 */
410
411
412void
413setinteractive(int on)
414{
415	static int is_interactive;
416
417	if (on == is_interactive)
418		return;
419	setsignal(SIGINT, 0);
420	setsignal(SIGQUIT, 0);
421	setsignal(SIGTERM, 0);
422	is_interactive = on;
423}
424
425
426
427/*
428 * Called to exit the shell.
429 */
430
431void
432exitshell(int status)
433{
434	struct jmploc loc1, loc2;
435	char *p;
436
437	TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
438	if (setjmp(loc1.loc)) {
439		goto l1;
440	}
441	if (setjmp(loc2.loc)) {
442		goto l2;
443	}
444	handler = &loc1;
445	if ((p = trap[0]) != NULL && *p != '\0') {
446		trap[0] = NULL;
447		evalstring(p, 0);
448	}
449l1:   handler = &loc2;			/* probably unnecessary */
450	flushall();
451#if JOBS
452	setjobctl(0);
453#endif
454l2:   _exit(status);
455	/* NOTREACHED */
456}
457