xref: /netbsd-src/bin/sh/trap.c (revision f8cf1a9151c7af1cb0bd8b09c13c66bca599c027)
1 /*	$NetBSD: trap.c,v 1.58 2024/10/09 13:43:33 kre 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
38 static char sccsid[] = "@(#)trap.c	8.5 (Berkeley) 6/5/95";
39 #else
40 __RCSID("$NetBSD: trap.c,v 1.58 2024/10/09 13:43:33 kre Exp $");
41 #endif
42 #endif /* not lint */
43 
44 #include <signal.h>
45 #include <unistd.h>
46 #include <stdlib.h>
47 #include <stdio.h>
48 #include <errno.h>
49 #include <limits.h>
50 #include <termios.h>
51 
52 #undef	CEOF	/* from <termios.h> but concflicts with sh use */
53 
54 #include <sys/ioctl.h>
55 #include <sys/resource.h>
56 
57 #include "shell.h"
58 #include "main.h"
59 #include "nodes.h"	/* for other headers */
60 #include "eval.h"
61 #include "jobs.h"
62 #include "show.h"
63 #include "options.h"
64 #include "builtins.h"
65 #include "syntax.h"
66 #include "output.h"
67 #include "memalloc.h"
68 #include "error.h"
69 #include "trap.h"
70 #include "mystring.h"
71 #include "var.h"
72 
73 #ifndef SMALL
74 #include "myhistedit.h"
75 #endif
76 
77 /*
78  * Sigmode records the current value of the signal handlers for the various
79  * modes.  A value of zero means that the current handler is not known.
80  * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
81  */
82 
83 #define S_DFL 1			/* default signal handling (SIG_DFL) */
84 #define S_CATCH 2		/* signal is caught */
85 #define S_IGN 3			/* signal is ignored (SIG_IGN) */
86 #define S_HARD_IGN 4		/* signal is ignored permenantly */
87 #define S_RESET 5		/* temporary - to reset a hard ignored sig */
88 
89 
90 MKINIT char sigmode[NSIG];	/* current value of signal */
91 static volatile sig_atomic_t gotsig[NSIG];/* indicates specified signal received */
92 volatile sig_atomic_t pendingsigs;	/* indicates some signal received */
93 
94 int traps_invalid;		/* in a subshell, but trap[] not yet cleared */
95 static char * volatile trap[NSIG];	/* trap handler commands */
96 static int in_dotrap;
97 static int last_trapsig;
98 
99 static int exiting;		/* exitshell() has been done */
100 static int exiting_status;	/* the status to use for exit() */
101 
102 static int getsigaction(int, sig_t *);
103 STATIC const char *trap_signame(int);
104 void printsignals(struct output *, int);
105 
106 /*
107  * return the signal number described by `p' (as a number or a name)
108  * or -1 if it isn't one
109  */
110 
111 int
112 signame_to_signum(const char *p)
113 {
114 	int i;
115 
116 	if (is_number(p))
117 		return number(p);
118 
119 	if (strcasecmp(p, "exit") == 0 )
120 		return 0;
121 
122 	i = signalnumber(p);
123 	if (i == 0)
124 		i = -1;
125 	return i;
126 }
127 
128 /*
129  * return the name of a signal used by the "trap" command
130  */
131 STATIC const char *
132 trap_signame(int signo)
133 {
134 	static char nbuf[12];
135 	const char *p;
136 
137 	if (signo == 0)
138 		return "EXIT";
139 	p = signalname(signo);
140 	if (p != NULL)
141 		return p;
142 	(void)snprintf(nbuf, sizeof nbuf, "%d", signo);
143 	return nbuf;
144 }
145 
146 #ifdef SMALL
147 /*
148  * Print a list of valid signal names
149  */
150 void
151 printsignals(struct output *out, int len)
152 {
153 	int n;
154 
155 	if (len != 0)
156 		outc(' ', out);
157 	for (n = 1; n < NSIG; n++) {
158 		outfmt(out, "%s", trap_signame(n));
159 		if ((n == NSIG/2) || n == (NSIG - 1))
160 			outstr("\n", out);
161 		else
162 			outc(' ', out);
163 	}
164 }
165 #else /* !SMALL */
166 /*
167  * Print the names of all the signals (neatly) to fp
168  * "len" gives the number of chars already printed to
169  * the current output line (in kill.c, always 0)
170  */
171 void
172 printsignals(struct output *out, int len)
173 {
174 	int sig;
175 	int nl, pad;
176 	const char *name;
177 	int termwidth = 80;
178 
179 	if ((name = bltinlookup("COLUMNS", 1)) != NULL)
180 		termwidth = (int)strtol(name, NULL, 10);
181 	else if (isatty(1)) {
182 		struct winsize win;
183 
184 		if (ioctl(1, TIOCGWINSZ, &win) == 0 && win.ws_col > 0)
185 			termwidth = win.ws_col;
186 	}
187 
188 	if (posix)
189 		pad = 1;
190 	else
191 		pad = (len | 7) + 1 - len;
192 
193 	for (sig = 0; (sig = signalnext(sig)) != 0; ) {
194 		name = signalname(sig);
195 		if (name == NULL)
196 			continue;
197 
198 		nl = strlen(name);
199 
200 		if (len > 0 && nl + len + pad >= termwidth) {
201 			outc('\n', out);
202 			len = 0;
203 			pad = 0;
204 		} else if (pad > 0 && len != 0)
205 			outfmt(out, "%*s", pad, "");
206 		else
207 			pad = 0;
208 
209 		len += nl + pad;
210 		if (!posix)
211 			pad = (nl | 7) + 1 - nl;
212 		else
213 			pad = 1;
214 
215 		outstr(name, out);
216 	}
217 	if (len != 0)
218 		outc('\n', out);
219 }
220 #endif /* SMALL */
221 
222 /*
223  * The trap builtin.
224  */
225 
226 int
227 trapcmd(int argc, char **argv)
228 {
229 	char *action;
230 	char **ap;
231 	int signo;
232 	int errs = 0;
233 	int printonly = 0;
234 
235 	ap = argv + 1;
236 
237 	CTRACE(DBG_TRAP, ("trapcmd: "));
238 	if (argc == 3 && strcmp(ap[1], "--") == 0)
239 		argc--;
240 	if (argc == 2 && strcmp(*ap, "-l") == 0) {
241 		CTRACE(DBG_TRAP, ("-l\n"));
242 		out1str("EXIT");
243 		printsignals(out1, 4);
244 		return 0;
245 	}
246 	if (argc == 2 && strcmp(*ap, "-") == 0) {
247 		CTRACE(DBG_TRAP, ("-\n"));
248 		for (signo = 0; signo < NSIG; signo++) {
249 			if (trap[signo] == NULL)
250 				continue;
251 			INTOFF;
252 			ckfree(trap[signo]);
253 			trap[signo] = NULL;
254 			if (signo != 0)
255 				setsignal(signo, 0);
256 			INTON;
257 		}
258 		traps_invalid = 0;
259 		return 0;
260 	}
261 	if (argc >= 2 && (strcmp(*ap, "-p") == 0 || strcmp(*ap, "-P") == 0)) {
262 		CTRACE(DBG_TRAP, ("%s ", *ap));
263 		printonly = 1 + (ap[0][1] == 'p');
264 		ap++;
265 		argc--;
266 	}
267 
268 	if (argc > 1 && strcmp(*ap, "--") == 0) {
269 		argc--;
270 		ap++;
271 	}
272 
273 	if (printonly == 1 && argc < 2)
274 		goto usage;
275 
276 	if (argc <= 1) {
277 		int count;
278 
279 		CTRACE(DBG_TRAP, ("*all*\n"));
280 		if (printonly) {
281 			for (count = 0, signo = 0 ; signo < NSIG ; signo++) {
282 				if (signo == SIGKILL || signo == SIGSTOP)
283 					continue;
284 				if (trap[signo] == NULL) {
285 					if (count == 0)
286 						out1str("trap -- -");
287 					out1fmt(" %s", trap_signame(signo));
288 					/* oh! unlucky 13 */
289 					if (++count >= 13) {
290 						out1str("\n");
291 						count = 0;
292 					}
293 				}
294 			}
295 			if (count)
296 				out1str("\n");
297 		}
298 
299 		/*
300 		 * We don't need do deal with SIGSTOP or SIGKILL as a
301 		 * special case anywhere here, as they cannot be
302 		 * ignored or caught - the only possibility is default
303 		 */
304 		for (count = 0, signo = 0 ; signo < NSIG ; signo++)
305 			if (trap[signo] != NULL && trap[signo][0] == '\0') {
306 				if (count == 0)
307 					out1str("trap -- ''");
308 				out1fmt(" %s", trap_signame(signo));
309 				/*
310 				 * the prefix is 10 bytes, with 4 byte
311 				 * signal names (common) we have room in
312 				 * the 70 bytes left on a normal line for
313 				 * 70/(4+1) signals, that's 14, but to
314 				 * allow for the occasional longer sig name
315 				 * we output one less...
316 				 */
317 				if (++count >= 13) {
318 					out1str("\n");
319 					count = 0;
320 				}
321 			}
322 		if (count)
323 			out1str("\n");
324 
325 		for (signo = 0 ; signo < NSIG ; signo++)
326 			if (trap[signo] != NULL && trap[signo][0] != '\0') {
327 				out1str("trap -- ");
328 				print_quoted(trap[signo]);
329 				out1fmt(" %s\n", trap_signame(signo));
330 			}
331 
332 		return 0;
333 	}
334 	CTRACE(DBG_TRAP, ("\n"));
335 
336 	action = NULL;
337 
338 	if (!printonly && traps_invalid)
339 		free_traps();
340 
341 	if (!printonly && !is_number(*ap)) {
342 		if ((*ap)[0] == '-' && (*ap)[1] == '\0')
343 			ap++;			/* reset to default */
344 		else
345 			action = *ap++;		/* can be '' for "ignore" */
346 		argc--;
347 	}
348 
349 	if (argc < 2) {		/* there must be at least 1 condition */
350  usage:
351 		out2str("Usage: trap [-l]\n"
352 			"       trap -p [condition ...]\n"
353 			"       trap -P  condition ...\n"
354 			"       trap action condition ...\n"
355 			"       trap N condition ...\n");
356 		return 2;
357 	}
358 
359 
360 	while (*ap) {
361 		signo = signame_to_signum(*ap);
362 
363 		if (signo < 0 || signo >= NSIG) {
364 			/* This is not a fatal error, so sayeth posix */
365 			outfmt(out2, "trap: '%s' bad condition\n", *ap);
366 			errs = 1;
367 			ap++;
368 			continue;
369 		}
370 		ap++;
371 
372 		if (printonly) {
373 			/*
374 			 * we allow SIGSTOP and SIGKILL to be obtained
375 			 * (action will always be "-") here, if someone
376 			 * really wants to get that particular output
377 			 */
378 			if (printonly == 1) {
379 				if (trap[signo] != NULL)
380 					out1fmt("%s\n", trap[signo]);
381 			} else {
382 				out1str("trap -- ");
383 				if (trap[signo] == NULL)
384 					out1str("-");
385 				else
386 					print_quoted(trap[signo]);
387 				out1fmt(" %s\n", trap_signame(signo));
388 			}
389 			continue;
390 		}
391 
392 		if ((signo == SIGKILL || signo == SIGSTOP) && action != NULL) {
393 #ifndef SMALL
394 			/*
395 			 * Don't bother with the error message in a SMALL shell
396 			 * just ignore req and  return error status silently
397 			 * (POSIX says this is an "undefined" operation so
398 			 * whatever we do is OK!)
399 			 *
400 			 * When we do generate an error, make it attempt match
401 			 * the user's operand, as best we can reasonably.
402 			 */
403 			outfmt(out2, "trap: '%s%s' cannot be %s\n",
404 			    (!is_alpha(ap[-1][0]) ||
405 				strncasecmp(ap[-1], "sig", 3) == 0) ? "" :
406 				is_upper(ap[-1][0]) ? "SIG" : "sig",
407 			    ap[-1], *action ? "caught" : "ignored");
408 #endif
409 			errs = 1;
410 			continue;
411 		}
412 
413 		INTOFF;
414 		if (action)
415 			action = savestr(action);
416 
417 		VTRACE(DBG_TRAP, ("trap for %d from %s%s%s to %s%s%s\n", signo,
418 			trap[signo] ? "'" : "", trap[signo] ? trap[signo] : "-",
419 			trap[signo] ? "'" : "", action ?  "'" : "",
420 			action ? action : "-", action ?  "'" : ""));
421 
422 		if (trap[signo])
423 			ckfree(trap[signo]);
424 
425 		trap[signo] = action;
426 
427 		if (signo != 0)
428 			setsignal(signo, 0);
429 		INTON;
430 	}
431 	return errs;
432 }
433 
434 
435 
436 /*
437  * Clear traps on a fork or vfork.
438  * Takes one arg vfork, to tell it to not be destructive of
439  * the parents variables.
440  */
441 void
442 clear_traps(int vforked)
443 {
444 	char * volatile *tp;
445 
446 	VTRACE(DBG_TRAP, ("clear_traps(%d)\n", vforked));
447 	if (!vforked)
448 		traps_invalid = 1;
449 
450 	for (tp = &trap[1] ; tp < &trap[NSIG] ; tp++) {
451 		if (*tp && **tp) {	/* trap not NULL or SIG_IGN */
452 			INTOFF;
453 			setsignal(tp - trap, vforked == 1);
454 			INTON;
455 		}
456 	}
457 	if (vforked == 2)
458 		free_traps();
459 }
460 
461 void
462 free_traps(void)
463 {
464 	char * volatile *tp;
465 
466 	VTRACE(DBG_TRAP, ("free_traps%s\n", traps_invalid ? "(invalid)" : ""));
467 	INTOFF;
468 	for (tp = trap ; tp < &trap[NSIG] ; tp++)
469 		if (*tp && **tp) {
470 			ckfree(*tp);
471 			*tp = NULL;
472 		}
473 	traps_invalid = 0;
474 	INTON;
475 }
476 
477 /*
478  * See if there are any defined traps
479  */
480 int
481 have_traps(void)
482 {
483 	char * volatile *tp;
484 
485 	if (traps_invalid)
486 		return 0;
487 
488 	for (tp = trap ; tp < &trap[NSIG] ; tp++)
489 		if (*tp && **tp)	/* trap not NULL or SIG_IGN */
490 			return 1;
491 	return 0;
492 }
493 
494 /*
495  * Set the signal handler for the specified signal.  The routine figures
496  * out what it should be set to.
497  */
498 void
499 setsignal(int signo, int vforked)
500 {
501 	int action;
502 	sig_t sigact = SIG_DFL, sig;
503 	char *t, tsig;
504 
505 	if (traps_invalid || (t = trap[signo]) == NULL)
506 		action = S_DFL;
507 	else if (*t != '\0')
508 		action = S_CATCH;
509 	else
510 		action = S_IGN;
511 
512 	VTRACE(DBG_TRAP, ("setsignal(%d%s) -> %d", signo,
513 	    vforked ? ", VF" : "", action));
514 	if (rootshell && !vforked && action == S_DFL) {
515 		switch (signo) {
516 		case SIGINT:
517 			if (iflag || minusc || sflag == 0)
518 				action = S_CATCH;
519 			break;
520 		case SIGQUIT:
521 #ifdef DEBUG
522 			if (debug)
523 				break;
524 #endif
525 			/* FALLTHROUGH */
526 		case SIGTERM:
527 			if (rootshell && iflag)
528 				action = S_IGN;
529 			break;
530 #if JOBS
531 		case SIGTSTP:
532 		case SIGTTOU:
533 			if (rootshell && mflag)
534 				action = S_IGN;
535 			break;
536 #endif
537 		}
538 	}
539 
540 	/*
541 	 * Never let users futz with SIGCHLD
542 	 * instead we will give them pseudo SIGCHLD's
543 	 * when background jobs complete.
544 	 */
545 	if (signo == SIGCHLD)
546 		action = S_DFL;
547 
548 	VTRACE(DBG_TRAP, (" -> %d", action));
549 
550 	t = &sigmode[signo];
551 	tsig = *t;
552 	if (tsig == 0) {
553 		/*
554 		 * current setting unknown
555 		 */
556 		if (!getsigaction(signo, &sigact)) {
557 			/*
558 			 * Pretend it worked; maybe we should give a warning
559 			 * here, but other shells don't. We don't alter
560 			 * sigmode, so that we retry every time.
561 			 */
562 			VTRACE(DBG_TRAP, (" getsigaction (%d)\n", errno));
563 			return;
564 		}
565 		VTRACE(DBG_TRAP, (" [%s]%s%s", sigact==SIG_IGN ? "IGN" :
566 		    sigact==SIG_DFL ? "DFL" : "caught",
567 		    iflag ? "i" : "", mflag ? "m" : ""));
568 
569 		if (sigact == SIG_IGN) {
570 			/*
571 			 * POSIX 3.14.13 states that non-interactive shells
572 			 * should ignore trap commands for signals that were
573 			 * ignored upon entry, and leaves the behavior
574 			 * unspecified for interactive shells. On interactive
575 			 * shells, or if job control is on, and we have a job
576 			 * control related signal, we allow the trap to work.
577 			 *
578 			 * This change allows us to be POSIX compliant, and
579 			 * at the same time override the default behavior if
580 			 * we need to by setting the interactive flag.
581 			 */
582 			if ((mflag && (signo == SIGTSTP ||
583 			     signo == SIGTTIN || signo == SIGTTOU)) || iflag) {
584 				tsig = S_IGN;
585 			} else
586 				tsig = S_HARD_IGN;
587 		} else {
588 			tsig = S_RESET;	/* force to be set */
589 		}
590 	}
591 	VTRACE(DBG_TRAP, (" tsig=%d\n", tsig));
592 
593 	if (tsig == S_HARD_IGN || tsig == action)
594 		return;
595 
596 	switch (action) {
597 		case S_DFL:	sigact = SIG_DFL;	break;
598 		case S_CATCH:	sigact = onsig;		break;
599 		case S_IGN:	sigact = SIG_IGN;	break;
600 	}
601 
602 	sig = signal(signo, sigact);
603 
604 	if (sig != SIG_ERR) {
605 		sigset_t ss;
606 
607 		if (!vforked)
608 			*t = action;
609 
610 		if (action == S_CATCH)
611 			(void)siginterrupt(signo, 1);
612 		/*
613 		 * If our parent accidentally blocked signals for
614 		 * us make sure we unblock them
615 		 */
616 		(void)sigemptyset(&ss);
617 		(void)sigaddset(&ss, signo);
618 		(void)sigprocmask(SIG_UNBLOCK, &ss, NULL);
619 	}
620 	return;
621 }
622 
623 /*
624  * Return the current setting for sig w/o changing it.
625  */
626 static int
627 getsigaction(int signo, sig_t *sigact)
628 {
629 	struct sigaction sa;
630 
631 	if (sigaction(signo, (struct sigaction *)0, &sa) == -1)
632 		return 0;
633 	*sigact = (sig_t) sa.sa_handler;
634 	return 1;
635 }
636 
637 /*
638  * Ignore a signal.
639  */
640 
641 void
642 ignoresig(int signo, int vforked)
643 {
644 	if (sigmode[signo] == 0)
645 		setsignal(signo, vforked);
646 
647 	VTRACE(DBG_TRAP, ("ignoresig(%d%s)\n", signo, vforked ? ", VF" : ""));
648 	if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) {
649 		signal(signo, SIG_IGN);
650 		if (!vforked)
651 			sigmode[signo] = S_IGN;
652 	}
653 }
654 
655 char *
656 child_trap(void)
657 {
658 	char * p;
659 
660 	p = trap[SIGCHLD];
661 
662 	if (traps_invalid || (p != NULL && *p == '\0'))
663 		p = NULL;
664 
665 	return p;
666 }
667 
668 
669 #ifdef mkinit
670 INCLUDE <signal.h>
671 INCLUDE "trap.h"
672 INCLUDE "shell.h"
673 INCLUDE "show.h"
674 
675 SHELLPROC {
676 	char *sm;
677 
678 	INTOFF;
679 	clear_traps(2);
680 	for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
681 		if (*sm == S_IGN) {
682 			*sm = S_HARD_IGN;
683 			VTRACE(DBG_TRAP, ("SHELLPROC: %d -> hard_ign\n",
684 			    (sm - sigmode)));
685 		}
686 	}
687 	INTON;
688 }
689 #endif
690 
691 
692 
693 /*
694  * Signal handler.
695  */
696 
697 void
698 onsig(int signo)
699 {
700 	int sav_err = errno;
701 
702 	CTRACE(DBG_SIG, ("onsig(%d), had: pendingsigs %d%s, gotsig[%d]=%d\n",
703 	    signo, pendingsigs, intpending ? " (SIGINT-pending)" : "",
704 	    signo, gotsig[signo]));
705 
706 	/*			This should not be needed.
707 	signal(signo, onsig);
708 	*/
709 
710 	if (signo == SIGINT && (traps_invalid || trap[SIGINT] == NULL)) {
711 		VTRACE(DBG_SIG, ("onsig(SIGINT), doing it now\n"));
712 		if (suppressint && !in_dotrap)
713 			intpending = 1;
714 		else
715 			onint();
716 		errno = sav_err;
717 		return;
718 	}
719 
720 	/*
721 	 * if the signal will do nothing, no point reporting it
722 	 */
723 	if (!traps_invalid && trap[signo] != NULL && trap[signo][0] != '\0' &&
724 	    signo != SIGCHLD) {
725 		gotsig[signo] = 1;
726 		pendingsigs++;
727 		if (iflag && signo == SIGINT) {
728 			if (!suppressint) {
729 				VTRACE(DBG_SIG,
730 			   ("onsig: -i gotsig[INT]->%d pendingsigs->%d  BANG\n",
731 				    gotsig[SIGINT], pendingsigs));
732 				onint();
733 				errno = sav_err;
734 				return;
735 			}
736 			intpending = 1;
737 		}
738 		VTRACE(DBG_SIG, ("onsig: gotsig[%d]->%d pendingsigs->%d%s\n",
739 		    signo, gotsig[signo], pendingsigs,
740 		    intpending ? " (SIGINT pending)":""));
741 	}
742 	errno = sav_err;
743 }
744 
745 
746 
747 /*
748  * Called to execute a trap.  Perhaps we should avoid entering new trap
749  * handlers while we are executing a trap handler.
750  */
751 
752 void
753 dotrap(void)
754 {
755 	int i;
756 	char *tr;
757 	int savestatus;
758 	struct skipsave saveskip;
759 
760 	CTRACE(DBG_TRAP|DBG_SIG, ("dotrap[%d]: %d pending, traps %sinvalid\n",
761 	    in_dotrap, pendingsigs, traps_invalid ? "" : "not "));
762 
763 	in_dotrap++;
764 	for (;;) {
765 		pendingsigs = 0;
766 		for (i = 1 ; ; i++) {
767 			if (i >= NSIG) {
768 				in_dotrap--;
769 				VTRACE(DBG_TRAP|DBG_SIG, ("dotrap[%d] done\n",
770 				    in_dotrap));
771 				return;
772 			}
773 			if (gotsig[i])
774 				break;
775 		}
776 		gotsig[i] = 0;
777 
778 		if (traps_invalid)
779 			continue;
780 
781 		tr = trap[i];
782 
783 		CTRACE(DBG_TRAP|DBG_SIG, ("dotrap %d: %s%s%s\n", i,
784 		    tr ? "\"" : "", tr ? tr : "NULL", tr ? "\"" : ""));
785 
786 		if (tr != NULL) {
787 			last_trapsig = i;
788 			save_skipstate(&saveskip);
789 			savestatus = exitstatus;
790 
791 			tr = savestr(tr);	/* trap code may free trap[i] */
792 			evalstring(tr, 0);
793 			ckfree(tr);
794 
795 			if (current_skipstate() == SKIPNONE ||
796 			    saveskip.state != SKIPNONE) {
797 				restore_skipstate(&saveskip);
798 				exitstatus = savestatus;
799 			}
800 		}
801 	}
802 }
803 
804 int
805 lastsig(void)
806 {
807 	int i;
808 
809 	for (i = NSIG; --i > 0; )
810 		if (gotsig[i])
811 			return i;
812 	return SIGINT;	/* XXX */
813 }
814 
815 /*
816  * Controls whether the shell is interactive or not.
817  */
818 
819 
820 void
821 setinteractive(int on)
822 {
823 	static int is_interactive;
824 
825 	if (on == is_interactive)
826 		return;
827 	setsignal(SIGINT, 0);
828 	setsignal(SIGQUIT, 0);
829 	setsignal(SIGTERM, 0);
830 	is_interactive = on;
831 }
832 
833 
834 
835 /*
836  * Called to exit the shell.
837  */
838 void
839 exitshell(int status)
840 {
841 	CTRACE(DBG_ERRS|DBG_PROCS|DBG_CMDS|DBG_TRAP,
842 	    ("pid %d: exitshell(%d)\n", getpid(), status));
843 
844 	exiting = 1;
845 	exiting_status = status;
846 	exitshell_savedstatus();
847 }
848 
849 void
850 exitshell_savedstatus(void)
851 {
852 	struct jmploc loc;
853 	char *p;
854 	volatile int sig = 0;
855 	int s;
856 	sigset_t sigs;
857 
858 	CTRACE(DBG_ERRS|DBG_PROCS|DBG_CMDS|DBG_TRAP,
859 	  ("pid %d: exitshell_savedstatus()%s $?=%d xs=%d dt=%d ts=%d\n",
860 	    getpid(), exiting ? " exiting" : "", exitstatus,
861 	    exiting_status, in_dotrap, last_trapsig));
862 
863 	if (!exiting) {
864 		if (in_dotrap && last_trapsig) {
865 			sig = last_trapsig;
866 			exiting_status = sig + 128;
867 		} else
868 			exiting_status = exitstatus;
869 	}
870 	exitstatus = exiting_status;
871 
872 	if (pendingsigs && !setjmp(loc.loc)) {
873 		handler = &loc;
874 
875 		dotrap();
876 	}
877 
878 	if (!setjmp(loc.loc)) {
879 		handler = &loc;
880 
881 		if (!traps_invalid && (p = trap[0]) != NULL && *p != '\0') {
882 			reset_eval();
883 			trap[0] = NULL;
884 			VTRACE(DBG_TRAP, ("exit trap: \"%s\"\n", p));
885 			evalstring(p, 0);
886 		}
887 	}
888 
889 	INTOFF;			/*  we're done, no more interrupts. */
890 
891 #ifndef SMALL
892 	if (rootshell)
893 		save_sh_history();
894 #endif
895 
896 	if (!setjmp(loc.loc)) {
897 		handler = &loc;		/* probably unnecessary */
898 		flushall();
899 #if JOBS
900 		setjobctl(0);
901 #endif
902 	}
903 
904 	if ((s = sig) != 0 && s != SIGSTOP && s != SIGTSTP && s != SIGTTIN &&
905 	    s != SIGTTOU) {
906 		struct rlimit nocore;
907 
908 		/*
909 		 * if the signal is of the core dump variety, don't...
910 		 */
911 		nocore.rlim_cur = nocore.rlim_max = 0;
912 		(void) setrlimit(RLIMIT_CORE, &nocore);
913 
914 		signal(s, SIG_DFL);
915 		sigemptyset(&sigs);
916 		sigaddset(&sigs, s);
917 		sigprocmask(SIG_UNBLOCK, &sigs, NULL);
918 
919 		VTRACE(DBG_ERRS|DBG_PROCS|DBG_CMDS|DBG_TRAP,
920 		    ("exitshell_savedstatus(): pid %d Death by signal %d\n",
921 			getpid(), s));
922 		kill(getpid(), s);
923 	}
924 	VTRACE(DBG_ERRS|DBG_PROCS|DBG_CMDS|DBG_TRAP,
925 	    ("exitshell_savedstatus(): pid %d exiting(%d)\n",
926 		getpid(), exiting_status));
927 	_exit(exiting_status);
928 	/* NOTREACHED */
929 }
930