1/*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Kenneth Almquist.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34#if 0
35static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
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39__FBSDID("$FreeBSD: head/bin/sh/trap.c 194127 2009-06-13 21:10:41Z jilles $");
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| 39__FBSDID("$FreeBSD: head/bin/sh/trap.c 199205 2009-11-11 23:13:24Z jilles $"); |
40
41#include <signal.h>
42#include <unistd.h>
43#include <stdlib.h>
44
45#include "shell.h"
46#include "main.h"
47#include "nodes.h" /* for other headers */
48#include "eval.h"
49#include "jobs.h"
50#include "show.h"
51#include "options.h"
52#include "syntax.h"
53#include "output.h"
54#include "memalloc.h"
55#include "error.h"
56#include "trap.h"
57#include "mystring.h"
58#include "myhistedit.h"
59
60
61/*
62 * Sigmode records the current value of the signal handlers for the various
63 * modes. A value of zero means that the current handler is not known.
64 * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
65 */
66
67#define S_DFL 1 /* default signal handling (SIG_DFL) */
68#define S_CATCH 2 /* signal is caught */
69#define S_IGN 3 /* signal is ignored (SIG_IGN) */
70#define S_HARD_IGN 4 /* signal is ignored permanently */
71#define S_RESET 5 /* temporary - to reset a hard ignored sig */
72
73
74MKINIT char sigmode[NSIG]; /* current value of signal */
75int pendingsigs; /* indicates some signal received */
76int in_dotrap; /* do we execute in a trap handler? */
77static char *volatile trap[NSIG]; /* trap handler commands */
78static volatile sig_atomic_t gotsig[NSIG];
79 /* indicates specified signal received */
80static int ignore_sigchld; /* Used while handling SIGCHLD traps. */
81volatile sig_atomic_t gotwinch;
82
83static int getsigaction(int, sig_t *);
84
85
86/*
87 * Map a string to a signal number.
88 *
89 * Note: the signal number may exceed NSIG.
90 */
91static int
92sigstring_to_signum(char *sig)
93{
94
95 if (is_number(sig)) {
96 int signo;
97
98 signo = atoi(sig);
99 return ((signo >= 0 && signo < NSIG) ? signo : (-1));
100 } else if (strcasecmp(sig, "exit") == 0) {
101 return (0);
102 } else {
103 int n;
104
105 if (strncasecmp(sig, "sig", 3) == 0)
106 sig += 3;
107 for (n = 1; n < sys_nsig; n++)
108 if (sys_signame[n] &&
109 strcasecmp(sys_signame[n], sig) == 0)
110 return (n);
111 }
112 return (-1);
113}
114
115
116/*
117 * Print a list of valid signal names.
118 */
119static void
120printsignals(void)
121{
122 int n, outlen;
123
124 outlen = 0;
125 for (n = 1; n < sys_nsig; n++) {
126 if (sys_signame[n]) {
127 out1fmt("%s", sys_signame[n]);
128 outlen += strlen(sys_signame[n]);
129 } else {
130 out1fmt("%d", n);
131 outlen += 3; /* good enough */
132 }
133 ++outlen;
134 if (outlen > 70 || n == sys_nsig - 1) {
135 out1str("\n");
136 outlen = 0;
137 } else {
138 out1c(' ');
139 }
140 }
141}
142
143
144/*
145 * The trap builtin.
146 */
147int
148trapcmd(int argc, char **argv)
149{
150 char *action;
151 int signo;
152
153 if (argc <= 1) {
154 for (signo = 0 ; signo < sys_nsig ; signo++) {
155 if (signo < NSIG && trap[signo] != NULL) {
156 out1str("trap -- ");
157 out1qstr(trap[signo]);
158 if (signo == 0) {
159 out1str(" exit\n");
160 } else if (sys_signame[signo]) {
161 out1fmt(" %s\n", sys_signame[signo]);
162 } else {
163 out1fmt(" %d\n", signo);
164 }
165 }
166 }
167 return 0;
168 }
169 action = NULL;
170 if (*++argv && strcmp(*argv, "--") == 0)
171 argv++;
172 if (*argv && sigstring_to_signum(*argv) == -1) {
173 if ((*argv)[0] != '-') {
174 action = *argv;
175 argv++;
176 } else if ((*argv)[1] == '\0') {
177 argv++;
178 } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') {
179 printsignals();
180 return 0;
181 } else {
182 error("bad option %s", *argv);
183 }
184 }
185 while (*argv) {
186 if ((signo = sigstring_to_signum(*argv)) == -1)
187 error("bad signal %s", *argv);
188 INTOFF;
189 if (action)
190 action = savestr(action);
191 if (trap[signo])
192 ckfree(trap[signo]);
193 trap[signo] = action;
194 if (signo != 0)
195 setsignal(signo);
196 INTON;
197 argv++;
198 }
199 return 0;
200}
201
202
203/*
204 * Clear traps on a fork.
205 */
206void
207clear_traps(void)
208{
209 char *volatile *tp;
210
211 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
212 if (*tp && **tp) { /* trap not NULL or SIG_IGN */
213 INTOFF;
214 ckfree(*tp);
215 *tp = NULL;
216 if (tp != &trap[0])
217 setsignal(tp - trap);
218 INTON;
219 }
220 }
221}
222
223
224/*
225 * Check if we have any traps enabled.
226 */
227int
228have_traps(void)
229{
230 char *volatile *tp;
231
232 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
233 if (*tp && **tp) /* trap not NULL or SIG_IGN */
234 return 1;
235 }
236 return 0;
237}
238
239/*
240 * Set the signal handler for the specified signal. The routine figures
241 * out what it should be set to.
242 */
243void
244setsignal(int signo)
245{
246 int action;
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247 sig_t sig, sigact = SIG_DFL;
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247 sig_t sigact = SIG_DFL;
248 struct sigaction sa; |
249 char *t;
250
251 if ((t = trap[signo]) == NULL)
252 action = S_DFL;
253 else if (*t != '\0')
254 action = S_CATCH;
255 else
256 action = S_IGN;
257 if (action == S_DFL) {
258 switch (signo) {
259 case SIGINT:
260 action = S_CATCH;
261 break;
262 case SIGQUIT:
263#ifdef DEBUG
264 {
265 extern int debug;
266
267 if (debug)
268 break;
269 }
270#endif
271 action = S_CATCH;
272 break;
273 case SIGTERM:
274 if (rootshell && iflag)
275 action = S_IGN;
276 break;
277#if JOBS
278 case SIGTSTP:
279 case SIGTTOU:
280 if (rootshell && mflag)
281 action = S_IGN;
282 break;
283#endif
284#ifndef NO_HISTORY
285 case SIGWINCH:
286 if (rootshell && iflag)
287 action = S_CATCH;
288 break;
289#endif
290 }
291 }
292
293 t = &sigmode[signo];
294 if (*t == 0) {
295 /*
296 * current setting unknown
297 */
298 if (!getsigaction(signo, &sigact)) {
299 /*
300 * Pretend it worked; maybe we should give a warning
301 * here, but other shells don't. We don't alter
302 * sigmode, so that we retry every time.
303 */
304 return;
305 }
306 if (sigact == SIG_IGN) {
307 if (mflag && (signo == SIGTSTP ||
308 signo == SIGTTIN || signo == SIGTTOU)) {
309 *t = S_IGN; /* don't hard ignore these */
310 } else
311 *t = S_HARD_IGN;
312 } else {
313 *t = S_RESET; /* force to be set */
314 }
315 }
316 if (*t == S_HARD_IGN || *t == action)
317 return;
318 switch (action) {
319 case S_DFL: sigact = SIG_DFL; break;
320 case S_CATCH: sigact = onsig; break;
321 case S_IGN: sigact = SIG_IGN; break;
322 }
323 *t = action;
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323 sig = signal(signo, sigact);
324 if (sig != SIG_ERR && action == S_CATCH)
325 siginterrupt(signo, 1);
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324 sa.sa_handler = sigact;
325 sa.sa_flags = 0;
326 sigemptyset(&sa.sa_mask);
327 sigaction(signo, &sa, NULL); |
328}
329
330
331/*
332 * Return the current setting for sig w/o changing it.
333 */
334static int
335getsigaction(int signo, sig_t *sigact)
336{
337 struct sigaction sa;
338
339 if (sigaction(signo, (struct sigaction *)0, &sa) == -1)
340 return 0;
341 *sigact = (sig_t) sa.sa_handler;
342 return 1;
343}
344
345
346/*
347 * Ignore a signal.
348 */
349void
350ignoresig(int signo)
351{
352
353 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) {
354 signal(signo, SIG_IGN);
355 }
356 sigmode[signo] = S_HARD_IGN;
357}
358
359
360#ifdef mkinit
361INCLUDE <signal.h>
362INCLUDE "trap.h"
363
364SHELLPROC {
365 char *sm;
366
367 clear_traps();
368 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
369 if (*sm == S_IGN)
370 *sm = S_HARD_IGN;
371 }
372}
373#endif
374
375
376/*
377 * Signal handler.
378 */
379void
380onsig(int signo)
381{
382
383 if (signo == SIGINT && trap[SIGINT] == NULL) {
384 onint();
385 return;
386 }
387
388 if (signo != SIGCHLD || !ignore_sigchld)
389 gotsig[signo] = 1;
390 pendingsigs++;
391
392 /* If we are currently in a wait builtin, prepare to break it */
393 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0)
394 breakwaitcmd = 1;
395 /*
396 * If a trap is set, not ignored and not the null command, we need
397 * to make sure traps are executed even when a child blocks signals.
398 */
399 if (Tflag &&
400 trap[signo] != NULL &&
401 ! (trap[signo][0] == '\0') &&
402 ! (trap[signo][0] == ':' && trap[signo][1] == '\0'))
403 breakwaitcmd = 1;
404
405#ifndef NO_HISTORY
406 if (signo == SIGWINCH)
407 gotwinch = 1;
408#endif
409}
410
411
412/*
413 * Called to execute a trap. Perhaps we should avoid entering new trap
414 * handlers while we are executing a trap handler.
415 */
416void
417dotrap(void)
418{
419 int i;
420 int savestatus;
421
422 in_dotrap++;
423 for (;;) {
424 for (i = 1; i < NSIG; i++) {
425 if (gotsig[i]) {
426 gotsig[i] = 0;
427 if (trap[i]) {
428 /*
429 * Ignore SIGCHLD to avoid infinite
430 * recursion if the trap action does
431 * a fork.
432 */
433 if (i == SIGCHLD)
434 ignore_sigchld++;
435 savestatus = exitstatus;
436 evalstring(trap[i], 0);
437 exitstatus = savestatus;
438 if (i == SIGCHLD)
439 ignore_sigchld--;
440 }
441 break;
442 }
443 }
444 if (i >= NSIG)
445 break;
446 }
447 in_dotrap--;
448 pendingsigs = 0;
449}
450
451
452/*
453 * Controls whether the shell is interactive or not.
454 */
455void
456setinteractive(int on)
457{
458 static int is_interactive = -1;
459
460 if (on == is_interactive)
461 return;
462 setsignal(SIGINT);
463 setsignal(SIGQUIT);
464 setsignal(SIGTERM);
465#ifndef NO_HISTORY
466 setsignal(SIGWINCH);
467#endif
468 is_interactive = on;
469}
470
471
472/*
473 * Called to exit the shell.
474 */
475void
476exitshell(int status)
477{
478 struct jmploc loc1, loc2;
479 char *p;
480
481 TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
482 if (setjmp(loc1.loc)) {
483 goto l1;
484 }
485 if (setjmp(loc2.loc)) {
486 goto l2;
487 }
488 handler = &loc1;
489 if ((p = trap[0]) != NULL && *p != '\0') {
490 trap[0] = NULL;
491 evalstring(p, 0);
492 }
493l1: handler = &loc2; /* probably unnecessary */
494 flushall();
495#if JOBS
496 setjobctl(0);
497#endif
498l2: _exit(status);
499}
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