1 /* signal.c -- signal handling ($Revision: 1.1.1.1 $) */
2
3 #include "es.h"
4 #include "sigmsgs.h"
5
6 typedef Sigresult (*Sighandler)(int);
7
8 Boolean sigint_newline = TRUE;
9
10 jmp_buf slowlabel;
11 Atomic slow = FALSE;
12 Atomic interrupted = FALSE;
13 static Atomic sigcount;
14 static Atomic caught[NSIG];
15 static Sigeffect sigeffect[NSIG];
16
17 #if HAVE_SIGACTION
18 #ifndef SA_NOCLDSTOP
19 #define SA_NOCLDSTOP 0
20 #endif
21 #ifndef SA_NOCLDWAIT
22 #define SA_NOCLDWAIT 0
23 #endif
24 #ifndef SA_INTERRUPT /* for sunos */
25 #define SA_INTERRUPT 0
26 #endif
27 #endif
28
29
30 /*
31 * name<->signal mappings
32 */
33
signumber(const char * name)34 extern int signumber(const char *name) {
35 int i;
36 char *suffix;
37 if (!hasprefix(name, "sig"))
38 return -1;
39 for (i = 0; i < nsignals; i++)
40 if (streq(signals[i].name, name))
41 return signals[i].sig;
42 i = strtol(name + 3, &suffix, 10);
43 if (0 < i && i < NSIG && (suffix == NULL || *suffix == '\0'))
44 return i;
45 return -1;
46 }
47
signame(int sig)48 extern char *signame(int sig) {
49 int i;
50 for (i = 0; i < nsignals; i++)
51 if (signals[i].sig == sig)
52 return (char *) signals[i].name;
53 return str("sig%d", sig);
54 }
55
sigmessage(int sig)56 extern char *sigmessage(int sig) {
57 int i;
58 for (i = 0; i < nsignals; i++)
59 if (signals[i].sig == sig)
60 return (char *) signals[i].msg;
61 return str("unknown signal %d", sig);
62 }
63
64
65 /*
66 * the signal handler
67 */
68
69 /* catcher -- catch (and defer) a signal from the kernel */
catcher(int sig)70 static void catcher(int sig) {
71 #if SYSV_SIGNALS /* only do this for unreliable signals */
72 signal(sig, catcher);
73 #endif
74 if (hasforked)
75 /* exit unconditionally on a signal in a child process */
76 exit(1);
77 if (caught[sig] == 0) {
78 caught[sig] = TRUE;
79 ++sigcount;
80 }
81 interrupted = TRUE;
82 if (slow)
83 longjmp(slowlabel, 1);
84 }
85
86
87 /*
88 * setting and getting signal effects
89 */
90
setsignal(int sig,Sighandler handler)91 static Sighandler setsignal(int sig, Sighandler handler) {
92 #if HAVE_SIGACTION
93 struct sigaction nsa, osa;
94 sigemptyset(&nsa.sa_mask);
95 nsa.sa_handler = handler;
96 nsa.sa_flags = SA_INTERRUPT;
97 if (sigaction(sig, &nsa, &osa) == -1)
98 return SIG_ERR;
99 return osa.sa_handler;
100 #else /* !HAVE_SIGACTION */
101 #ifdef SIGCLD
102 if (sig == SIGCLD && handler != SIG_DFL)
103 return SIG_ERR;
104 #endif
105 return signal(sig, handler);
106 #endif /* !HAVE_SIGACTION */
107 }
108
esignal(int sig,Sigeffect effect)109 extern Sigeffect esignal(int sig, Sigeffect effect) {
110 Sigeffect old;
111 assert(0 < sig && sig <= NSIG);
112 old = sigeffect[sig];
113 if (effect != sig_nochange && effect != old) {
114 switch (effect) {
115 case sig_ignore:
116 if (setsignal(sig, SIG_IGN) == SIG_ERR) {
117 eprint("$&setsignals: cannot ignore %s\n", signame(sig));
118 return old;
119 }
120 break;
121 case sig_special:
122 if (sig != SIGINT) {
123 eprint("$&setsignals: special handler not defined for %s\n", signame(sig));
124 return old;
125 }
126 case sig_catch:
127 case sig_noop:
128 if (setsignal(sig, catcher) == SIG_ERR) {
129 eprint("$&setsignals: cannot catch %s\n", signame(sig));
130 return old;
131 }
132 break;
133 case sig_default:
134 setsignal(sig, SIG_DFL);
135 break;
136 default:
137 NOTREACHED;
138 }
139 sigeffect[sig] = effect;
140 }
141 return old;
142 }
143
setsigeffects(const Sigeffect effects[])144 extern void setsigeffects(const Sigeffect effects[]) {
145 int sig;
146 for (sig = 1; sig < NSIG; sig++)
147 esignal(sig, effects[sig]);
148 }
149
getsigeffects(Sigeffect effects[])150 extern void getsigeffects(Sigeffect effects[]) {
151 memcpy(effects, sigeffect, sizeof sigeffect);
152 }
153
154
155 /*
156 * initialization
157 */
158
initsignals(Boolean interactive,Boolean allowdumps)159 extern void initsignals(Boolean interactive, Boolean allowdumps) {
160 int sig;
161 Push settor;
162
163 for (sig = 0; sig < nsignals; sig++)
164 if (signals[sig].sig < 1 || NSIG <= signals[sig].sig)
165 panic(
166 "initsignals: bad signal in sigmsgs.c: %s (see mksignal)",
167 signals[sig].name
168 );
169
170 for (sig = 1; sig < NSIG; sig++) {
171 Sighandler h;
172 #if HAVE_SIGACTION
173 struct sigaction sa;
174 sigaction(sig, NULL, &sa);
175 h = sa.sa_handler;
176 if (h == SIG_IGN)
177 sigeffect[sig] = sig_ignore;
178 #else /* !HAVE_SIGACTION */
179 h = signal(sig, SIG_DFL);
180 if (h == SIG_IGN) {
181 setsignal(sig, SIG_IGN);
182 sigeffect[sig] = sig_ignore;
183 }
184 #endif /* !HAVE_SIGACTION */
185 else if (h == SIG_DFL || h == SIG_ERR)
186 sigeffect[sig] = sig_default;
187 else
188 panic(
189 "initsignals: bad incoming signal value for %s: %x",
190 signame(sig), h
191 );
192 }
193
194 if (interactive || sigeffect[SIGINT] == sig_default)
195 esignal(SIGINT, sig_special);
196 if (!allowdumps) {
197 if (interactive)
198 esignal(SIGTERM, sig_noop);
199 if (interactive || sigeffect[SIGQUIT] == sig_default)
200 esignal(SIGQUIT, sig_noop);
201 }
202
203 /* here's the end-run around set-signals */
204 varpush(&settor, "set-signals", NULL);
205 vardef("signals", NULL, mksiglist());
206 varpop(&settor);
207 }
208
setsigdefaults(void)209 extern void setsigdefaults(void) {
210 int sig;
211 for (sig = 1; sig < NSIG; sig++) {
212 Sigeffect e = sigeffect[sig];
213 if (e == sig_catch || e == sig_noop || e == sig_special)
214 esignal(sig, sig_default);
215 }
216 }
217
218
219 /*
220 * utility functions
221 */
222
issilentsignal(List * e)223 extern Boolean issilentsignal(List *e) {
224 return (termeq(e->term, "signal"))
225 && e->next != NULL
226 && termeq(e->next->term, "sigint");
227 }
228
mksiglist(void)229 extern List *mksiglist(void) {
230 int sig = NSIG;
231 Sigeffect effects[NSIG];
232 getsigeffects(effects);
233 Ref(List *, lp, NULL);
234 while (--sig > 0) {
235 int prefix;
236 switch (effects[sig]) {
237 default: panic("mksiglist: bad sigeffects for %s: %d", signame(sig), effects[sig]);
238 case sig_default: continue;
239 case sig_catch: prefix = '\0'; break;
240 case sig_ignore: prefix = '-'; break;
241 case sig_noop: prefix = '/'; break;
242 case sig_special: prefix = '.'; break;
243 }
244 Ref(char *, name, signame(sig));
245 if (prefix != '\0')
246 name = str("%c%s", prefix, name);
247 Ref(Term *, term, mkstr(name));
248 lp = mklist(term, lp);
249 RefEnd2(term, name);
250 }
251 RefReturn(lp);
252 }
253
254
255 /*
256 * signal delivery
257 */
258
259 static int blocked = 0;
260
261 /* blocksignals -- turn off delivery of signals as exceptions */
blocksignals(void)262 extern void blocksignals(void) {
263 assert(blocked >= 0);
264 ++blocked;
265 }
266
267 /* unblocksignals -- turn on delivery of signals as exceptions */
unblocksignals(void)268 extern void unblocksignals(void) {
269 assert(blocked > 0);
270 --blocked;
271 }
272
273 /* sigchk -- throw the signal as an exception */
sigchk(void)274 extern void sigchk(void) {
275 int sig;
276
277 if (sigcount == 0 || blocked)
278 return;
279 if (hasforked)
280 /* exit unconditionally on a signal in a child process */
281 exit(1);
282
283 for (sig = 0;; sig++) {
284 if (caught[sig] != 0) {
285 --sigcount;
286 caught[sig] = 0;
287 break;
288 }
289 if (sig >= NSIG) {
290 sigcount = 0;
291 return;
292 }
293 }
294 resetparser();
295 Ref(List *, e,
296 mklist(mkstr("signal"), mklist(mkstr(signame(sig)), NULL)));
297
298 switch (sigeffect[sig]) {
299 case sig_catch:
300 while (gcisblocked())
301 gcenable();
302 throw(e);
303 NOTREACHED;
304 case sig_special:
305 assert(sig == SIGINT);
306 /* this is the newline you see when you hit ^C while typing a command */
307 if (sigint_newline)
308 eprint("\n");
309 sigint_newline = TRUE;
310 while (gcisblocked())
311 gcenable();
312 throw(e);
313 NOTREACHED;
314 break;
315 case sig_noop:
316 break;
317 default:
318 /* panic("sigchk: caught %L with sigeffect %d", e, " ", sigeffect[sig]); */
319 break;
320 }
321 RefEnd(e);
322 }
323