usr/dash/trap.c

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1997-2005
 *	Herbert Xu <herbert@gondor.apana.org.au>.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include "shell.h"
#include "main.h"
#include "nodes.h"	/* for other headers */
#include "eval.h"
#include "jobs.h"
#include "show.h"
#include "options.h"
#include "syntax.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "trap.h"
#include "mystring.h"

#ifdef HETIO
#include "hetio.h"
#endif

/*
 * Sigmode records the current value of the signal handlers for the various
 * modes.  A value of zero means that the current handler is not known.
 * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
 */

#define S_DFL 1			/* default signal handling (SIG_DFL) */
#define S_CATCH 2		/* signal is caught */
#define S_IGN 3			/* signal is ignored (SIG_IGN) */
#define S_HARD_IGN 4		/* signal is ignored permenantly */
#define S_RESET 5		/* temporary - to reset a hard ignored sig */


/* trap handler commands */
char *trap[NSIG];
/* current value of signal */
static char sigmode[NSIG - 1];
/* indicates specified signal received */
char gotsig[NSIG - 1];
/* last pending signal */
volatile sig_atomic_t pendingsigs;
/* do we generate EXSIG events */
int exsig;

#ifdef mkinit
INCLUDE <signal.h>
INIT {
	signal(SIGCHLD, SIG_DFL);
}
#endif

/*
 * The trap builtin.
 */

int
trapcmd(int argc, char **argv)
{
	char *action;
	char **ap;
	int signo;

	nextopt(nullstr);
	ap = argptr;
	if (!*ap) {
		for (signo = 0 ; signo < NSIG ; signo++) {
			if (trap[signo] != NULL) {
				out1fmt(
					"trap -- %s %s\n",
					single_quote(trap[signo]),
					signal_name(signo)
				);
			}
		}
		return 0;
	}
	if (!ap[1])
		action = NULL;
	else
		action = *ap++;
	while (*ap) {
		if ((signo = decode_signal(*ap, 0)) < 0)
			sh_error("%s: bad trap", *ap);
		INTOFF;
		if (action) {
			if (action[0] == '-' && action[1] == '\0')
				action = NULL;
			else
				action = savestr(action);
		}
		if (trap[signo])
			ckfree(trap[signo]);
		trap[signo] = action;
		if (signo != 0)
			setsignal(signo);
		INTON;
		ap++;
	}
	return 0;
}


/*
 * Clear traps on a fork.
 */

void
clear_traps(void)
{
	char **tp;

	for (tp = trap ; tp < &trap[NSIG] ; tp++) {
		if (*tp && **tp) {	/* trap not NULL or SIG_IGN */
			INTOFF;
			ckfree(*tp);
			*tp = NULL;
			if (tp != &trap[0])
				setsignal(tp - trap);
			INTON;
		}
	}
}


/*
 * Set the signal handler for the specified signal.  The routine figures
 * out what it should be set to.
 */

void
setsignal(int signo)
{
	int action;
	char *t, tsig;
	struct sigaction act;

	if ((t = trap[signo]) == NULL)
		action = S_DFL;
	else if (*t != '\0')
		action = S_CATCH;
	else
		action = S_IGN;
	if (rootshell && action == S_DFL) {
		switch (signo) {
		case SIGINT:
			if (iflag || minusc || sflag == 0)
				action = S_CATCH;
			break;
		case SIGQUIT:
#ifdef DEBUG
			if (debug)
				break;
#endif
			/* FALLTHROUGH */
		case SIGTERM:
			if (iflag)
				action = S_IGN;
			break;
#if JOBS
		case SIGTSTP:
		case SIGTTOU:
			if (mflag)
				action = S_IGN;
			break;
#endif
		}
	}

	t = &sigmode[signo - 1];
	tsig = *t;
	if (tsig == 0) {
		/*
		 * current setting unknown
		 */
		if (sigaction(signo, 0, &act) == -1) {
			/*
			 * Pretend it worked; maybe we should give a warning
			 * here, but other shells don't. We don't alter
			 * sigmode, so that we retry every time.
			 */
			return;
		}
		if (act.sa_handler == SIG_IGN) {
			if (mflag && (signo == SIGTSTP ||
			     signo == SIGTTIN || signo == SIGTTOU)) {
				tsig = S_IGN;	/* don't hard ignore these */
			} else
				tsig = S_HARD_IGN;
		} else {
			tsig = S_RESET;	/* force to be set */
		}
	}
	if (tsig == S_HARD_IGN || tsig == action)
		return;
	switch (action) {
	case S_CATCH:
		act.sa_handler = onsig;
		break;
	case S_IGN:
		act.sa_handler = SIG_IGN;
		break;
	default:
		act.sa_handler = SIG_DFL;
	}
	*t = action;
	act.sa_flags = 0;
	sigfillset(&act.sa_mask);
	sigaction(signo, &act, 0);
}

/*
 * Ignore a signal.
 */

void
ignoresig(int signo)
{
	if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
		signal(signo, SIG_IGN);
	}
	sigmode[signo - 1] = S_HARD_IGN;
}


/*
 * Signal handler.
 */

void
onsig(int signo)
{
	gotsig[signo - 1] = 1;
	pendingsigs = signo;

	if (exsig || (signo == SIGINT && !trap[SIGINT])) {
		if (!suppressint)
			onint();
		intpending = 1;
	}
}


/*
 * Called to execute a trap.  Perhaps we should avoid entering new trap
 * handlers while we are executing a trap handler.
 */

int
dotrap(void)
{
	char *p;
	char *q;
	int i;
	int savestatus;
	int skip = 0;

	savestatus = exitstatus;
	pendingsigs = 0;
	barrier();

	for (i = 0, q = gotsig; i < NSIG - 1; i++, q++) {
		if (!*q)
			continue;
		*q = 0;

		p = trap[i + 1];
		if (!p)
			continue;
		skip = evalstring(p, SKIPEVAL);
		exitstatus = savestatus;
		if (skip)
			break;
	}

	return skip;
}


/*
 * Controls whether the shell is interactive or not.
 */


void
setinteractive(int on)
{
	static int is_interactive;

	if (++on == is_interactive)
		return;
	is_interactive = on;
	setsignal(SIGINT);
	setsignal(SIGQUIT);
	setsignal(SIGTERM);
}


/*
 * Called to exit the shell.
 */

void
exitshell(void)
{
	struct jmploc loc;
	char *p;
	int status;

#ifdef HETIO
	hetio_reset_term();
#endif
	status = exitstatus;
	TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
	if (setjmp(loc.loc)) {
		if (exception == EXEXIT)
			_exit(exitstatus);
		goto out;
	}
	handler = &loc;
	if ((p = trap[0])) {
		trap[0] = NULL;
		evalstring(p, 0);
	}
	flushall();
out:
	_exit(status);
	/* NOTREACHED */
}

/*
 * Decode a signal name
 */
int decode_signal(const char *string, int minsig)
{
	int i;

	if (is_number(string)) {
		i = atoi(string);
		if (i >= NSIG) {
			return -1;
		}
		return i;
	}

	for ( i = minsig ; i < NSIG ; i++ ) {
		if ( sys_sigabbrev[i] &&
		     !strcasecmp(string, sys_sigabbrev[i]) )
			return i;
	}

#ifdef SIGRTMIN
	if ( !strncasecmp(string, "RTMIN", 5) ) {
		char *ep;

		if ( string[5] && string[5] != '+' )
			return -1;
		i = SIGRTMIN + strtol(string+5, &ep, 10);
		if ( *ep || i < SIGRTMIN || i > SIGRTMAX )
			return -1;
		return i;
	}

	if ( !strncasecmp(string, "RTMAX", 5) ) {
		char *ep;

		if ( string[5] && string[5] != '-' )
			return -1;
		i = SIGRTMAX + strtol(string+5, &ep, 10);
		if ( *ep || i < SIGRTMIN || i > SIGRTMAX )
			return -1;
		return i;
	}
#endif

	return -1;
}

/*
 * Human-readable signal name
 */
const char *
signal_name(int sig)
{
	static char buf[64];

	if ( sig < 0 || sig >= NSIG ) {
		return NULL;
	} else if ( sys_sigabbrev[sig] ) {
		return sys_sigabbrev[sig];
#ifdef SIGRTMIN
	} else if ( sig >= SIGRTMIN && sig <= SIGRTMAX ) {
		snprintf(buf, sizeof buf, "RTMIN+%d", sig-SIGRTMIN);
		return buf;
#endif
	} else {
		snprintf(buf, sizeof buf, "%d", sig);
		return buf;
	}
}
1	/*-
2	* Copyright (c) 1991, 1993
3	* The Regents of the University of California. All rights reserved.
4	* Copyright (c) 1997-2005
5	* Herbert Xu <herbert@gondor.apana.org.au>. 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 <signal.h>
36	#include <unistd.h>
37	#include <stdlib.h>
38	#include <string.h>
39	#include <stdio.h>
40
41	#include "shell.h"
42	#include "main.h"
43	#include "nodes.h" /* for other headers */
44	#include "eval.h"
45	#include "jobs.h"
46	#include "show.h"
47	#include "options.h"
48	#include "syntax.h"
49	#include "output.h"
50	#include "memalloc.h"
51	#include "error.h"
52	#include "trap.h"
53	#include "mystring.h"
54
55	#ifdef HETIO
56	#include "hetio.h"
57	#endif
58
59	/*
60	* Sigmode records the current value of the signal handlers for the various
61	* modes. A value of zero means that the current handler is not known.
62	* S_HARD_IGN indicates that the signal was ignored on entry to the shell,
63	*/
64
65	#define S_DFL 1 /* default signal handling (SIG_DFL) */
66	#define S_CATCH 2 /* signal is caught */
67	#define S_IGN 3 /* signal is ignored (SIG_IGN) */
68	#define S_HARD_IGN 4 /* signal is ignored permenantly */
69	#define S_RESET 5 /* temporary - to reset a hard ignored sig */
70
71
72	/* trap handler commands */
73	char *trap[NSIG];
74	/* current value of signal */
75	static char sigmode[NSIG - 1];
76	/* indicates specified signal received */
77	char gotsig[NSIG - 1];
78	/* last pending signal */
79	volatile sig_atomic_t pendingsigs;
80	/* do we generate EXSIG events */
81	int exsig;
82
83	#ifdef mkinit
84	INCLUDE <signal.h>
85	INIT {
86	signal(SIGCHLD, SIG_DFL);
87	}
88	#endif
89
90	/*
91	* The trap builtin.
92	*/
93
94	int
95	trapcmd(int argc, char **argv)
96	{
97	char *action;
98	char **ap;
99	int signo;
100
101	nextopt(nullstr);
102	ap = argptr;
103	if (!*ap) {
104	for (signo = 0 ; signo < NSIG ; signo++) {
105	if (trap[signo] != NULL) {
106	out1fmt(
107	"trap -- %s %s\n",
108	single_quote(trap[signo]),
109	signal_name(signo)
110	);
111	}
112	}
113	return 0;
114	}
115	if (!ap[1])
116	action = NULL;
117	else
118	action = *ap++;
119	while (*ap) {
120	if ((signo = decode_signal(*ap, 0)) < 0)
121	sh_error("%s: bad trap", *ap);
122	INTOFF;
123	if (action) {
124	if (action[0] == '-' && action[1] == '\0')
125	action = NULL;
126	else
127	action = savestr(action);
128	}
129	if (trap[signo])
130	ckfree(trap[signo]);
131	trap[signo] = action;
132	if (signo != 0)
133	setsignal(signo);
134	INTON;
135	ap++;
136	}
137	return 0;
138	}
139
140
141
142	/*
143	* Clear traps on a fork.
144	*/
145
146	void
147	clear_traps(void)
148	{
149	char **tp;
150
151	for (tp = trap ; tp < &trap[NSIG] ; tp++) {
152	if (tp && tp) { / trap not NULL or SIG_IGN */
153	INTOFF;
154	ckfree(*tp);
155	*tp = NULL;
156	if (tp != &trap[0])
157	setsignal(tp - trap);
158	INTON;
159	}
160	}
161	}
162
163
164
165	/*
166	* Set the signal handler for the specified signal. The routine figures
167	* out what it should be set to.
168	*/
169
170	void
171	setsignal(int signo)
172	{
173	int action;
174	char *t, tsig;
175	struct sigaction act;
176
177	if ((t = trap[signo]) == NULL)
178	action = S_DFL;
179	else if (*t != '\0')
180	action = S_CATCH;
181	else
182	action = S_IGN;
183	if (rootshell && action == S_DFL) {
184	switch (signo) {
185	case SIGINT:
186	if (iflag \|\| minusc \|\| sflag == 0)
187	action = S_CATCH;
188	break;
189	case SIGQUIT:
190	#ifdef DEBUG
191	if (debug)
192	break;
193	#endif
194	/* FALLTHROUGH */
195	case SIGTERM:
196	if (iflag)
197	action = S_IGN;
198	break;
199	#if JOBS
200	case SIGTSTP:
201	case SIGTTOU:
202	if (mflag)
203	action = S_IGN;
204	break;
205	#endif
206	}
207	}
208
209	t = &sigmode[signo - 1];
210	tsig = *t;
211	if (tsig == 0) {
212	/*
213	* current setting unknown
214	*/
215	if (sigaction(signo, 0, &act) == -1) {
216	/*
217	* Pretend it worked; maybe we should give a warning
218	* here, but other shells don't. We don't alter
219	* sigmode, so that we retry every time.
220	*/
221	return;
222	}
223	if (act.sa_handler == SIG_IGN) {
224	if (mflag && (signo == SIGTSTP \|\|
225	signo == SIGTTIN \|\| signo == SIGTTOU)) {
226	tsig = S_IGN; /* don't hard ignore these */
227	} else
228	tsig = S_HARD_IGN;
229	} else {
230	tsig = S_RESET; /* force to be set */
231	}
232	}
233	if (tsig == S_HARD_IGN \|\| tsig == action)
234	return;
235	switch (action) {
236	case S_CATCH:
237	act.sa_handler = onsig;
238	break;
239	case S_IGN:
240	act.sa_handler = SIG_IGN;
241	break;
242	default:
243	act.sa_handler = SIG_DFL;
244	}
245	*t = action;
246	act.sa_flags = 0;
247	sigfillset(&act.sa_mask);
248	sigaction(signo, &act, 0);
249	}
250
251	/*
252	* Ignore a signal.
253	*/
254
255	void
256	ignoresig(int signo)
257	{
258	if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
259	signal(signo, SIG_IGN);
260	}
261	sigmode[signo - 1] = S_HARD_IGN;
262	}
263
264
265
266	/*
267	* Signal handler.
268	*/
269
270	void
271	onsig(int signo)
272	{
273	gotsig[signo - 1] = 1;
274	pendingsigs = signo;
275
276	if (exsig \|\| (signo == SIGINT && !trap[SIGINT])) {
277	if (!suppressint)
278	onint();
279	intpending = 1;
280	}
281	}
282
283
284
285	/*
286	* Called to execute a trap. Perhaps we should avoid entering new trap
287	* handlers while we are executing a trap handler.
288	*/
289
290	int
291	dotrap(void)
292	{
293	char *p;
294	char *q;
295	int i;
296	int savestatus;
297	int skip = 0;
298
299	savestatus = exitstatus;
300	pendingsigs = 0;
301	barrier();
302
303	for (i = 0, q = gotsig; i < NSIG - 1; i++, q++) {
304	if (!*q)
305	continue;
306	*q = 0;
307
308	p = trap[i + 1];
309	if (!p)
310	continue;
311	skip = evalstring(p, SKIPEVAL);
312	exitstatus = savestatus;
313	if (skip)
314	break;
315	}
316
317	return skip;
318	}
319
320
321
322	/*
323	* Controls whether the shell is interactive or not.
324	*/
325
326
327	void
328	setinteractive(int on)
329	{
330	static int is_interactive;
331
332	if (++on == is_interactive)
333	return;
334	is_interactive = on;
335	setsignal(SIGINT);
336	setsignal(SIGQUIT);
337	setsignal(SIGTERM);
338	}
339
340
341
342	/*
343	* Called to exit the shell.
344	*/
345
346	void
347	exitshell(void)
348	{
349	struct jmploc loc;
350	char *p;
351	int status;
352
353	#ifdef HETIO
354	hetio_reset_term();
355	#endif
356	status = exitstatus;
357	TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
358	if (setjmp(loc.loc)) {
359	if (exception == EXEXIT)
360	_exit(exitstatus);
361	goto out;
362	}
363	handler = &loc;
364	if ((p = trap[0])) {
365	trap[0] = NULL;
366	evalstring(p, 0);
367	}
368	flushall();
369	out:
370	_exit(status);
371	/* NOTREACHED */
372	}
373
374	/*
375	* Decode a signal name
376	*/
377	int decode_signal(const char *string, int minsig)
378	{
379	int i;
380
381	if (is_number(string)) {
382	i = atoi(string);
383	if (i >= NSIG) {
384	return -1;
385	}
386	return i;
387	}
388
389	for ( i = minsig ; i < NSIG ; i++ ) {
390	if ( sys_sigabbrev[i] &&
391	!strcasecmp(string, sys_sigabbrev[i]) )
392	return i;
393	}
394
395	#ifdef SIGRTMIN
396	if ( !strncasecmp(string, "RTMIN", 5) ) {
397	char *ep;
398
399	if ( string[5] && string[5] != '+' )
400	return -1;
401	i = SIGRTMIN + strtol(string+5, &ep, 10);
402	if ( *ep \|\| i < SIGRTMIN \|\| i > SIGRTMAX )
403	return -1;
404	return i;
405	}
406
407	if ( !strncasecmp(string, "RTMAX", 5) ) {
408	char *ep;
409
410	if ( string[5] && string[5] != '-' )
411	return -1;
412	i = SIGRTMAX + strtol(string+5, &ep, 10);
413	if ( *ep \|\| i < SIGRTMIN \|\| i > SIGRTMAX )
414	return -1;
415	return i;
416	}
417	#endif
418
419	return -1;
420	}
421
422	/*
423	* Human-readable signal name
424	*/
425	const char *
426	signal_name(int sig)
427	{
428	static char buf[64];
429
430	if ( sig < 0 \|\| sig >= NSIG ) {
431	return NULL;
432	} else if ( sys_sigabbrev[sig] ) {
433	return sys_sigabbrev[sig];
434	#ifdef SIGRTMIN
435	} else if ( sig >= SIGRTMIN && sig <= SIGRTMAX ) {
436	snprintf(buf, sizeof buf, "RTMIN+%d", sig-SIGRTMIN);
437	return buf;
438	#endif
439	} else {
440	snprintf(buf, sizeof buf, "%d", sig);
441	return buf;
442	}
443	}