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 * %sccs.include.redist.c%
9 */
10
11 #ifndef lint
12 static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 06/05/95";
13 #endif /* not lint */
14
15 #include <signal.h>
16 #include <unistd.h>
17 #include <stdlib.h>
18
19 #include "shell.h"
20 #include "main.h"
21 #include "nodes.h" /* for other headers */
22 #include "eval.h"
23 #include "jobs.h"
24 #include "show.h"
25 #include "options.h"
26 #include "syntax.h"
27 #include "output.h"
28 #include "memalloc.h"
29 #include "error.h"
30 #include "trap.h"
31 #include "mystring.h"
32
33
34 /*
35 * Sigmode records the current value of the signal handlers for the various
36 * modes. A value of zero means that the current handler is not known.
37 * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
38 */
39
40 #define S_DFL 1 /* default signal handling (SIG_DFL) */
41 #define S_CATCH 2 /* signal is caught */
42 #define S_IGN 3 /* signal is ignored (SIG_IGN) */
43 #define S_HARD_IGN 4 /* signal is ignored permenantly */
44 #define S_RESET 5 /* temporary - to reset a hard ignored sig */
45
46
47 extern char nullstr[1]; /* null string */
48
49 char *trap[NSIG+1]; /* trap handler commands */
50 MKINIT char sigmode[NSIG]; /* current value of signal */
51 char gotsig[NSIG]; /* indicates specified signal received */
52 int pendingsigs; /* indicates some signal received */
53
54 static int getsigaction __P((int, sig_t *));
55
56 /*
57 * The trap builtin.
58 */
59
60 int
trapcmd(argc,argv)61 trapcmd(argc, argv)
62 int argc;
63 char **argv;
64 {
65 char *action;
66 char **ap;
67 int signo;
68
69 if (argc <= 1) {
70 for (signo = 0 ; signo <= NSIG ; signo++) {
71 if (trap[signo] != NULL)
72 out1fmt("%d: %s\n", signo, trap[signo]);
73 }
74 return 0;
75 }
76 ap = argv + 1;
77 if (is_number(*ap))
78 action = NULL;
79 else
80 action = *ap++;
81 while (*ap) {
82 if ((signo = number(*ap)) < 0 || signo > NSIG)
83 error("%s: bad trap", *ap);
84 INTOFF;
85 if (action)
86 action = savestr(action);
87 if (trap[signo])
88 ckfree(trap[signo]);
89 trap[signo] = action;
90 if (signo != 0)
91 setsignal(signo);
92 INTON;
93 ap++;
94 }
95 return 0;
96 }
97
98
99
100 /*
101 * Clear traps on a fork.
102 */
103
104 void
clear_traps()105 clear_traps() {
106 char **tp;
107
108 for (tp = trap ; tp <= &trap[NSIG] ; tp++) {
109 if (*tp && **tp) { /* trap not NULL or SIG_IGN */
110 INTOFF;
111 ckfree(*tp);
112 *tp = NULL;
113 if (tp != &trap[0])
114 setsignal(tp - trap);
115 INTON;
116 }
117 }
118 }
119
120
121
122 /*
123 * Set the signal handler for the specified signal. The routine figures
124 * out what it should be set to.
125 */
126
127 long
setsignal(signo)128 setsignal(signo)
129 int signo;
130 {
131 int action;
132 sig_t sigact = SIG_DFL;
133 char *t;
134 extern void onsig();
135
136 if ((t = trap[signo]) == NULL)
137 action = S_DFL;
138 else if (*t != '\0')
139 action = S_CATCH;
140 else
141 action = S_IGN;
142 if (rootshell && action == S_DFL) {
143 switch (signo) {
144 case SIGINT:
145 if (iflag)
146 action = S_CATCH;
147 break;
148 case SIGQUIT:
149 #ifdef DEBUG
150 {
151 extern int debug;
152
153 if (debug)
154 break;
155 }
156 #endif
157 /* FALLTHROUGH */
158 case SIGTERM:
159 if (iflag)
160 action = S_IGN;
161 break;
162 #if JOBS
163 case SIGTSTP:
164 case SIGTTOU:
165 if (mflag)
166 action = S_IGN;
167 break;
168 #endif
169 }
170 }
171
172 t = &sigmode[signo - 1];
173 if (*t == 0) {
174 /*
175 * current setting unknown
176 */
177 if (!getsigaction(signo, &sigact)) {
178 /*
179 * Pretend it worked; maybe we should give a warning
180 * here, but other shells don't. We don't alter
181 * sigmode, so that we retry every time.
182 */
183 return 0;
184 }
185 if (sigact == SIG_IGN) {
186 if (mflag && (signo == SIGTSTP ||
187 signo == SIGTTIN || signo == SIGTTOU)) {
188 *t = S_IGN; /* don't hard ignore these */
189 } else
190 *t = S_HARD_IGN;
191 } else {
192 *t = S_RESET; /* force to be set */
193 }
194 }
195 if (*t == S_HARD_IGN || *t == action)
196 return 0;
197 switch (action) {
198 case S_DFL: sigact = SIG_DFL; break;
199 case S_CATCH: sigact = onsig; break;
200 case S_IGN: sigact = SIG_IGN; break;
201 }
202 *t = action;
203 return (long)signal(signo, sigact);
204 }
205
206 /*
207 * Return the current setting for sig w/o changing it.
208 */
209 static int
getsigaction(signo,sigact)210 getsigaction(signo, sigact)
211 int signo;
212 sig_t *sigact;
213 {
214 struct sigaction sa;
215
216 if (sigaction(signo, (struct sigaction *)0, &sa) == -1)
217 return 0;
218 *sigact = (sig_t) sa.sa_handler;
219 return 1;
220 }
221
222 /*
223 * Ignore a signal.
224 */
225
226 void
ignoresig(signo)227 ignoresig(signo)
228 int signo;
229 {
230 if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
231 signal(signo, SIG_IGN);
232 }
233 sigmode[signo - 1] = S_HARD_IGN;
234 }
235
236
237 #ifdef mkinit
238 INCLUDE <signal.h>
239 INCLUDE "trap.h"
240
241 SHELLPROC {
242 char *sm;
243
244 clear_traps();
245 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
246 if (*sm == S_IGN)
247 *sm = S_HARD_IGN;
248 }
249 }
250 #endif
251
252
253
254 /*
255 * Signal handler.
256 */
257
258 void
onsig(signo)259 onsig(signo)
260 int signo;
261 {
262 signal(signo, onsig);
263 if (signo == SIGINT && trap[SIGINT] == NULL) {
264 onint();
265 return;
266 }
267 gotsig[signo - 1] = 1;
268 pendingsigs++;
269 }
270
271
272
273 /*
274 * Called to execute a trap. Perhaps we should avoid entering new trap
275 * handlers while we are executing a trap handler.
276 */
277
278 void
dotrap()279 dotrap() {
280 int i;
281 int savestatus;
282
283 for (;;) {
284 for (i = 1 ; ; i++) {
285 if (gotsig[i - 1])
286 break;
287 if (i >= NSIG)
288 goto done;
289 }
290 gotsig[i - 1] = 0;
291 savestatus=exitstatus;
292 evalstring(trap[i]);
293 exitstatus=savestatus;
294 }
295 done:
296 pendingsigs = 0;
297 }
298
299
300
301 /*
302 * Controls whether the shell is interactive or not.
303 */
304
305
306 void
setinteractive(on)307 setinteractive(on)
308 int on;
309 {
310 static int is_interactive;
311
312 if (on == is_interactive)
313 return;
314 setsignal(SIGINT);
315 setsignal(SIGQUIT);
316 setsignal(SIGTERM);
317 is_interactive = on;
318 }
319
320
321
322 /*
323 * Called to exit the shell.
324 */
325
326 void
exitshell(status)327 exitshell(status)
328 int status;
329 {
330 struct jmploc loc1, loc2;
331 char *p;
332
333 TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
334 if (setjmp(loc1.loc)) {
335 goto l1;
336 }
337 if (setjmp(loc2.loc)) {
338 goto l2;
339 }
340 handler = &loc1;
341 if ((p = trap[0]) != NULL && *p != '\0') {
342 trap[0] = NULL;
343 evalstring(p);
344 }
345 l1: handler = &loc2; /* probably unnecessary */
346 flushall();
347 #if JOBS
348 setjobctl(0);
349 #endif
350 l2: _exit(status);
351 }
352