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 */
char sigmode[NSIG - 1];
/* indicates specified signal received */
static char gotsig[NSIG - 1];
/* last pending signal */
volatile sig_atomic_t pendingsigs;

#ifdef mkinit
INCLUDE "trap.h"
INIT {
	sigmode[SIGCHLD - 1] = S_DFL;
	setsignal(SIGCHLD);
}
#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) {
			outfmt(out2, "trap: %s: bad trap\n", *ap);
			return 1;
		}
		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
		}
	}

	if (signo == SIGCHLD)
		action = S_CATCH;

	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 (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;

	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;
		evalstring(p, 0);
		exitstatus = savestatus;
		if (evalskip)
			return evalskip;
	}

	return 0;
}


/*
 * 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)
			status = exitstatus;
		goto out;
	}
	handler = &loc;
	if ((p = trap[0])) {
		trap[0] = NULL;
		evalskip = 0;
		evalstring(p, 0);
	}
out:
	/*
	 * Disable job control so that whoever had the foreground before we
	 * started can get it back.
	 */
	if (likely(!setjmp(loc.loc)))
		setjobctl(0);
	flushall();
	_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	char sigmode[NSIG - 1];
76	/* indicates specified signal received */
77	static char gotsig[NSIG - 1];
78	/* last pending signal */
79	volatile sig_atomic_t pendingsigs;
80
81	#ifdef mkinit
82	INCLUDE "trap.h"
83	INIT {
84	sigmode[SIGCHLD - 1] = S_DFL;
85	setsignal(SIGCHLD);
86	}
87	#endif
88
89	/*
90	* The trap builtin.
91	*/
92
93	int
94	trapcmd(int argc, char **argv)
95	{
96	char *action;
97	char **ap;
98	int signo;
99
100	nextopt(nullstr);
101	ap = argptr;
102	if (!*ap) {
103	for (signo = 0 ; signo < NSIG ; signo++) {
104	if (trap[signo] != NULL) {
105	out1fmt(
106	"trap -- %s %s\n",
107	single_quote(trap[signo]),
108	signal_name(signo)
109	);
110	}
111	}
112	return 0;
113	}
114	if (!ap[1])
115	action = NULL;
116	else
117	action = *ap++;
118	while (*ap) {
119	if ((signo = decode_signal(*ap, 0)) < 0) {
120	outfmt(out2, "trap: %s: bad trap\n", *ap);
121	return 1;
122	}
123	INTOFF;
124	if (action) {
125	if (action[0] == '-' && action[1] == '\0')
126	action = NULL;
127	else
128	action = savestr(action);
129	}
130	if (trap[signo])
131	ckfree(trap[signo]);
132	trap[signo] = action;
133	if (signo != 0)
134	setsignal(signo);
135	INTON;
136	ap++;
137	}
138	return 0;
139	}
140
141
142
143	/*
144	* Clear traps on a fork.
145	*/
146
147	void
148	clear_traps(void)
149	{
150	char **tp;
151
152	for (tp = trap ; tp < &trap[NSIG] ; tp++) {
153	if (tp && tp) { / trap not NULL or SIG_IGN */
154	INTOFF;
155	ckfree(*tp);
156	*tp = NULL;
157	if (tp != &trap[0])
158	setsignal(tp - trap);
159	INTON;
160	}
161	}
162	}
163
164
165
166	/*
167	* Set the signal handler for the specified signal. The routine figures
168	* out what it should be set to.
169	*/
170
171	void
172	setsignal(int signo)
173	{
174	int action;
175	char *t, tsig;
176	struct sigaction act;
177
178	if ((t = trap[signo]) == NULL)
179	action = S_DFL;
180	else if (*t != '\0')
181	action = S_CATCH;
182	else
183	action = S_IGN;
184	if (rootshell && action == S_DFL) {
185	switch (signo) {
186	case SIGINT:
187	if (iflag \|\| minusc \|\| sflag == 0)
188	action = S_CATCH;
189	break;
190	case SIGQUIT:
191	#ifdef DEBUG
192	if (debug)
193	break;
194	#endif
195	/* FALLTHROUGH */
196	case SIGTERM:
197	if (iflag)
198	action = S_IGN;
199	break;
200	#if JOBS
201	case SIGTSTP:
202	case SIGTTOU:
203	if (mflag)
204	action = S_IGN;
205	break;
206	#endif
207	}
208	}
209
210	if (signo == SIGCHLD)
211	action = S_CATCH;
212
213	t = &sigmode[signo - 1];
214	tsig = *t;
215	if (tsig == 0) {
216	/*
217	* current setting unknown
218	*/
219	if (sigaction(signo, 0, &act) == -1) {
220	/*
221	* Pretend it worked; maybe we should give a warning
222	* here, but other shells don't. We don't alter
223	* sigmode, so that we retry every time.
224	*/
225	return;
226	}
227	if (act.sa_handler == SIG_IGN) {
228	if (mflag && (signo == SIGTSTP \|\|
229	signo == SIGTTIN \|\| signo == SIGTTOU)) {
230	tsig = S_IGN; /* don't hard ignore these */
231	} else
232	tsig = S_HARD_IGN;
233	} else {
234	tsig = S_RESET; /* force to be set */
235	}
236	}
237	if (tsig == S_HARD_IGN \|\| tsig == action)
238	return;
239	switch (action) {
240	case S_CATCH:
241	act.sa_handler = onsig;
242	break;
243	case S_IGN:
244	act.sa_handler = SIG_IGN;
245	break;
246	default:
247	act.sa_handler = SIG_DFL;
248	}
249	*t = action;
250	act.sa_flags = 0;
251	sigfillset(&act.sa_mask);
252	sigaction(signo, &act, 0);
253	}
254
255	/*
256	* Ignore a signal.
257	*/
258
259	void
260	ignoresig(int signo)
261	{
262	if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
263	signal(signo, SIG_IGN);
264	}
265	sigmode[signo - 1] = S_HARD_IGN;
266	}
267
268
269
270	/*
271	* Signal handler.
272	*/
273
274	void
275	onsig(int signo)
276	{
277	gotsig[signo - 1] = 1;
278	pendingsigs = signo;
279
280	if (signo == SIGINT && !trap[SIGINT]) {
281	if (!suppressint)
282	onint();
283	intpending = 1;
284	}
285	}
286
287
288
289	/*
290	* Called to execute a trap. Perhaps we should avoid entering new trap
291	* handlers while we are executing a trap handler.
292	*/
293
294	int
295	dotrap(void)
296	{
297	char *p;
298	char *q;
299	int i;
300	int savestatus;
301
302	savestatus = exitstatus;
303	pendingsigs = 0;
304	barrier();
305
306	for (i = 0, q = gotsig; i < NSIG - 1; i++, q++) {
307	if (!*q)
308	continue;
309	*q = 0;
310
311	p = trap[i + 1];
312	if (!p)
313	continue;
314	evalstring(p, 0);
315	exitstatus = savestatus;
316	if (evalskip)
317	return evalskip;
318	}
319
320	return 0;
321	}
322
323
324
325	/*
326	* Controls whether the shell is interactive or not.
327	*/
328
329
330	void
331	setinteractive(int on)
332	{
333	static int is_interactive;
334
335	if (++on == is_interactive)
336	return;
337	is_interactive = on;
338	setsignal(SIGINT);
339	setsignal(SIGQUIT);
340	setsignal(SIGTERM);
341	}
342
343
344
345	/*
346	* Called to exit the shell.
347	*/
348
349	void
350	exitshell(void)
351	{
352	struct jmploc loc;
353	char *p;
354	int status;
355
356	#ifdef HETIO
357	hetio_reset_term();
358	#endif
359	status = exitstatus;
360	TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
361	if (setjmp(loc.loc)) {
362	if (exception == EXEXIT)
363	status = exitstatus;
364	goto out;
365	}
366	handler = &loc;
367	if ((p = trap[0])) {
368	trap[0] = NULL;
369	evalskip = 0;
370	evalstring(p, 0);
371	}
372	out:
373	/*
374	* Disable job control so that whoever had the foreground before we
375	* started can get it back.
376	*/
377	if (likely(!setjmp(loc.loc)))
378	setjobctl(0);
379	flushall();
380	_exit(status);
381	/* NOTREACHED */
382	}
383
384	/*
385	* Decode a signal name
386	*/
387	int decode_signal(const char *string, int minsig)
388	{
389	int i;
390
391	if (is_number(string)) {
392	i = atoi(string);
393	if (i >= NSIG) {
394	return -1;
395	}
396	return i;
397	}
398
399	for ( i = minsig ; i < NSIG ; i++ ) {
400	if ( sys_sigabbrev[i] &&
401	!strcasecmp(string, sys_sigabbrev[i]) )
402	return i;
403	}
404
405	#ifdef SIGRTMIN
406	if ( !strncasecmp(string, "RTMIN", 5) ) {
407	char *ep;
408
409	if ( string[5] && string[5] != '+' )
410	return -1;
411	i = SIGRTMIN + strtol(string+5, &ep, 10);
412	if ( *ep \|\| i < SIGRTMIN \|\| i > SIGRTMAX )
413	return -1;
414	return i;
415	}
416
417	if ( !strncasecmp(string, "RTMAX", 5) ) {
418	char *ep;
419
420	if ( string[5] && string[5] != '-' )
421	return -1;
422	i = SIGRTMAX + strtol(string+5, &ep, 10);
423	if ( *ep \|\| i < SIGRTMIN \|\| i > SIGRTMAX )
424	return -1;
425	return i;
426	}
427	#endif
428
429	return -1;
430	}
431
432	/*
433	* Human-readable signal name
434	*/
435	const char *
436	signal_name(int sig)
437	{
438	static char buf[64];
439
440	if ( sig < 0 \|\| sig >= NSIG ) {
441	return NULL;
442	} else if ( sys_sigabbrev[sig] ) {
443	return sys_sigabbrev[sig];
444	#ifdef SIGRTMIN
445	} else if ( sig >= SIGRTMIN && sig <= SIGRTMAX ) {
446	snprintf(buf, sizeof buf, "RTMIN+%d", sig-SIGRTMIN);
447	return buf;
448	#endif
449	} else {
450	snprintf(buf, sizeof buf, "%d", sig);
451	return buf;
452	}
453	}