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	niro	532	/*-
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	niro	1122	char sigmode[NSIG - 1];
76	niro	532	/* indicates specified signal received */
77	niro	1122	static char gotsig[NSIG - 1];
78	niro	532	/* last pending signal */
79			volatile sig_atomic_t pendingsigs;
80
81			#ifdef mkinit
82	niro	1122	INCLUDE "trap.h"
83	niro	532	INIT {
84	niro	1122	sigmode[SIGCHLD - 1] = S_DFL;
85			setsignal(SIGCHLD);
86	niro	532	}
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	niro	1122	if ((signo = decode_signal(*ap, 0)) < 0) {
120			outfmt(out2, "trap: %s: bad trap\n", *ap);
121			return 1;
122			}
123	niro	532	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	niro	1122	if (signo == SIGCHLD)
211			action = S_CATCH;
212
213	niro	532	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	niro	1122	if (signo == SIGINT && !trap[SIGINT]) {
281	niro	532	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	niro	1122	evalstring(p, 0);
315	niro	532	exitstatus = savestatus;
316	niro	815	if (evalskip)
317			return evalskip;
318	niro	532	}
319
320	niro	815	return 0;
321	niro	532	}
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	niro	1122	status = exitstatus;
364	niro	532	goto out;
365			}
366			handler = &loc;
367			if ((p = trap[0])) {
368			trap[0] = NULL;
369	niro	1122	evalskip = 0;
370	niro	532	evalstring(p, 0);
371			}
372	niro	1122	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	niro	532	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			}