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Date:: Sat Oct 23 02:59:33 2004 UTC
Message:: clean up signal handling
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  1 9acaad45 2004-10-23 devnull /*
  2 9acaad45 2004-10-23 devnull  * Signal handling for Plan 9 programs. 
  3 9acaad45 2004-10-23 devnull  * We stubbornly use the strings from Plan 9 instead 
  4 9acaad45 2004-10-23 devnull  * of the enumerated Unix constants.  
  5 9acaad45 2004-10-23 devnull  * There are some weird translations.  In particular,
  6 9acaad45 2004-10-23 devnull  * a "kill" note is the same as SIGTERM in Unix.
  7 9acaad45 2004-10-23 devnull  * There is no equivalent note to Unix's SIGKILL, since
  8 9acaad45 2004-10-23 devnull  * it's not a deliverable signal anyway.
  9 9acaad45 2004-10-23 devnull  *
 10 9acaad45 2004-10-23 devnull  * We do not handle SIGABRT or SIGSEGV, mainly so that
 11 9acaad45 2004-10-23 devnull  * stack traces show the original source of the signal instead
 12 9acaad45 2004-10-23 devnull  * of notifysigf.
 13 9acaad45 2004-10-23 devnull  *
 14 9acaad45 2004-10-23 devnull  * We have to add some extra entry points to provide the
 15 9acaad45 2004-10-23 devnull  * ability to tweak which signals are deliverable and which
 16 9acaad45 2004-10-23 devnull  * are acted upon.  Notifydisable and notifyenable play with
 17 9acaad45 2004-10-23 devnull  * the process signal mask.  Notifyignore enables the signal
 18 9acaad45 2004-10-23 devnull  * but will not call notifyf when it comes in.  This is occasionally
 19 9acaad45 2004-10-23 devnull  * useful.
 20 9acaad45 2004-10-23 devnull  */
 21 9acaad45 2004-10-23 devnull 
 22 fd04aace 2003-11-23 devnull #include <u.h>
 23 8ad51794 2004-03-25 devnull #include <signal.h>
 24 fd04aace 2003-11-23 devnull #define NOPLAN9DEFINES
 25 fd04aace 2003-11-23 devnull #include <libc.h>
 26 fd04aace 2003-11-23 devnull 
 27 fd04aace 2003-11-23 devnull extern char *_p9sigstr(int, char*);
 28 9acaad45 2004-10-23 devnull extern int _p9strsig(char*);
 29 fd04aace 2003-11-23 devnull 
 30 9acaad45 2004-10-23 devnull typedef struct Sig Sig;
 31 9acaad45 2004-10-23 devnull struct Sig
 32 9acaad45 2004-10-23 devnull {
 33 9acaad45 2004-10-23 devnull 	int sig;			/* signal number */
 34 9acaad45 2004-10-23 devnull 	int restart;			/* do we restart the system call after this signal is handled? */
 35 9acaad45 2004-10-23 devnull 	int enabled;		/* is this signal enabled (not masked)? */
 36 9acaad45 2004-10-23 devnull 	int notified;		/* do we call the notify function for this signal? */
 37 9acaad45 2004-10-23 devnull };
 38 9acaad45 2004-10-23 devnull 
 39 9acaad45 2004-10-23 devnull /* initial settings; for current status, ask the kernel */
 40 9acaad45 2004-10-23 devnull static Sig sigs[] = {
 41 9acaad45 2004-10-23 devnull 	SIGHUP, 0, 1, 1,
 42 9acaad45 2004-10-23 devnull 	SIGINT, 0, 1, 1,
 43 9acaad45 2004-10-23 devnull 	SIGQUIT, 0, 1, 1,
 44 9acaad45 2004-10-23 devnull 	SIGILL, 0, 1, 1,
 45 9acaad45 2004-10-23 devnull 	SIGTRAP, 0, 1, 1,
 46 9acaad45 2004-10-23 devnull /*	SIGABRT, 0, 1, 1,	*/
 47 d2c4ee9e 2003-11-24 devnull #ifdef SIGEMT
 48 9acaad45 2004-10-23 devnull 	SIGEMT, 0, 1, 1,
 49 d2c4ee9e 2003-11-24 devnull #endif
 50 9acaad45 2004-10-23 devnull 	SIGFPE, 0, 1, 1,
 51 9acaad45 2004-10-23 devnull 	SIGBUS, 0, 1, 1,
 52 9acaad45 2004-10-23 devnull /*	SIGSEGV, 0, 1, 1,	*/
 53 9acaad45 2004-10-23 devnull 	SIGCHLD, 1, 0, 1,
 54 9acaad45 2004-10-23 devnull 	SIGSYS, 0, 1, 1,
 55 9acaad45 2004-10-23 devnull 	SIGPIPE, 0, 0, 1,
 56 9acaad45 2004-10-23 devnull 	SIGALRM, 0, 1, 1,
 57 9acaad45 2004-10-23 devnull 	SIGTERM, 0, 1, 1,
 58 9acaad45 2004-10-23 devnull 	SIGTSTP, 1, 0, 1,
 59 9acaad45 2004-10-23 devnull 	SIGTTIN, 1, 0, 1,
 60 9acaad45 2004-10-23 devnull 	SIGTTOU, 1, 0, 1,
 61 9acaad45 2004-10-23 devnull 	SIGXCPU, 0, 1, 1,
 62 9acaad45 2004-10-23 devnull 	SIGXFSZ, 0, 1, 1,
 63 9acaad45 2004-10-23 devnull 	SIGVTALRM, 0, 1, 1,
 64 9acaad45 2004-10-23 devnull 	SIGUSR1, 0, 1, 1,
 65 9acaad45 2004-10-23 devnull 	SIGUSR2, 0, 1, 1,
 66 9acaad45 2004-10-23 devnull 	SIGWINCH, 1, 0, 1,
 67 d2c4ee9e 2003-11-24 devnull #ifdef SIGINFO
 68 9acaad45 2004-10-23 devnull 	SIGINFO, 1, 1, 1,
 69 d2c4ee9e 2003-11-24 devnull #endif
 70 fd04aace 2003-11-23 devnull };
 71 fd04aace 2003-11-23 devnull 
 72 9acaad45 2004-10-23 devnull static Sig*
 73 9acaad45 2004-10-23 devnull findsig(int s)
 74 9acaad45 2004-10-23 devnull {
 75 9acaad45 2004-10-23 devnull 	int i;
 76 9acaad45 2004-10-23 devnull 
 77 9acaad45 2004-10-23 devnull 	for(i=0; i<nelem(sigs); i++)
 78 9acaad45 2004-10-23 devnull 		if(sigs[i].sig == s)
 79 9acaad45 2004-10-23 devnull 			return &sigs[i];
 80 9acaad45 2004-10-23 devnull 	return nil;
 81 9acaad45 2004-10-23 devnull }
 82 9acaad45 2004-10-23 devnull 
 83 9acaad45 2004-10-23 devnull /*
 84 9acaad45 2004-10-23 devnull  * The thread library initializes _notejmpbuf to its own
 85 9acaad45 2004-10-23 devnull  * routine which provides a per-pthread jump buffer.
 86 9acaad45 2004-10-23 devnull  * If we're not using the thread library, we assume we are
 87 9acaad45 2004-10-23 devnull  * single-threaded.
 88 9acaad45 2004-10-23 devnull  */
 89 05d8c6df 2004-09-23 devnull typedef struct Jmp Jmp;
 90 05d8c6df 2004-09-23 devnull struct Jmp
 91 05d8c6df 2004-09-23 devnull {
 92 05d8c6df 2004-09-23 devnull 	p9jmp_buf b;
 93 05d8c6df 2004-09-23 devnull };
 94 05d8c6df 2004-09-23 devnull 
 95 05d8c6df 2004-09-23 devnull static Jmp onejmp;
 96 05d8c6df 2004-09-23 devnull 
 97 05d8c6df 2004-09-23 devnull static Jmp*
 98 05d8c6df 2004-09-23 devnull getonejmp(void)
 99 05d8c6df 2004-09-23 devnull {
100 05d8c6df 2004-09-23 devnull 	return &onejmp;
101 05d8c6df 2004-09-23 devnull }
102 05d8c6df 2004-09-23 devnull 
103 05d8c6df 2004-09-23 devnull Jmp *(*_notejmpbuf)(void) = getonejmp;
104 9acaad45 2004-10-23 devnull static void noteinit(void);
105 fd04aace 2003-11-23 devnull 
106 9acaad45 2004-10-23 devnull /*
107 9acaad45 2004-10-23 devnull  * Actual signal handler. 
108 9acaad45 2004-10-23 devnull  */
109 aa200fe3 2004-10-22 devnull 
110 9acaad45 2004-10-23 devnull static void (*notifyf)(void*, char*);	/* Plan 9 handler */
111 9acaad45 2004-10-23 devnull 
112 aa200fe3 2004-10-22 devnull static void
113 9acaad45 2004-10-23 devnull signotify(int sig)
114 fd04aace 2003-11-23 devnull {
115 fd04aace 2003-11-23 devnull 	int v;
116 fd04aace 2003-11-23 devnull 	char tmp[64];
117 05d8c6df 2004-09-23 devnull 	Jmp *j;
118 fd04aace 2003-11-23 devnull 
119 05d8c6df 2004-09-23 devnull 	j = (*_notejmpbuf)();
120 9acaad45 2004-10-23 devnull 	switch(p9setjmp(j->b)){
121 9acaad45 2004-10-23 devnull 	case 0:
122 9acaad45 2004-10-23 devnull 		if(notifyf)
123 9acaad45 2004-10-23 devnull 			(*notifyf)(nil, _p9sigstr(sig, tmp));
124 9acaad45 2004-10-23 devnull 		/* fall through */
125 9acaad45 2004-10-23 devnull 	case 1:	/* noted(NDFLT) */
126 9acaad45 2004-10-23 devnull 		if(0)print("DEFAULT %d\n", sig);
127 9acaad45 2004-10-23 devnull 		signal(sig, SIG_DFL);
128 9acaad45 2004-10-23 devnull 		raise(sig);
129 9acaad45 2004-10-23 devnull 		_exit(1);
130 9acaad45 2004-10-23 devnull 	case 2:	/* noted(NCONT) */
131 05d8c6df 2004-09-23 devnull 		if(0)print("HANDLED %d\n", sig);
132 fd04aace 2003-11-23 devnull 		return;
133 fd04aace 2003-11-23 devnull 	}
134 fd04aace 2003-11-23 devnull }
135 05d8c6df 2004-09-23 devnull 
136 9acaad45 2004-10-23 devnull static void
137 9acaad45 2004-10-23 devnull signonotify(int sig)
138 9acaad45 2004-10-23 devnull {
139 9acaad45 2004-10-23 devnull 	USED(sig);
140 9acaad45 2004-10-23 devnull }
141 9acaad45 2004-10-23 devnull 
142 fd04aace 2003-11-23 devnull int
143 05d8c6df 2004-09-23 devnull noted(int v)
144 05d8c6df 2004-09-23 devnull {
145 05d8c6df 2004-09-23 devnull 	p9longjmp((*_notejmpbuf)()->b, v==NCONT ? 2 : 1);
146 05d8c6df 2004-09-23 devnull 	abort();
147 05d8c6df 2004-09-23 devnull 	return 0;
148 05d8c6df 2004-09-23 devnull }
149 05d8c6df 2004-09-23 devnull 
150 9acaad45 2004-10-23 devnull int
151 9acaad45 2004-10-23 devnull notify(void (*f)(void*, char*))
152 9acaad45 2004-10-23 devnull {
153 9acaad45 2004-10-23 devnull 	int i;
154 9acaad45 2004-10-23 devnull 	static int init;
155 9acaad45 2004-10-23 devnull 
156 9acaad45 2004-10-23 devnull 	notifyf = f;
157 9acaad45 2004-10-23 devnull 	if(!init){
158 9acaad45 2004-10-23 devnull 		init = 1;
159 9acaad45 2004-10-23 devnull 		noteinit();
160 9acaad45 2004-10-23 devnull 	}
161 9acaad45 2004-10-23 devnull 	return 0;
162 9acaad45 2004-10-23 devnull }
163 9acaad45 2004-10-23 devnull 
164 9acaad45 2004-10-23 devnull /*
165 9acaad45 2004-10-23 devnull  * Nonsense about enabling and disabling signals.
166 9acaad45 2004-10-23 devnull  */
167 9acaad45 2004-10-23 devnull static void(*)(int)
168 9acaad45 2004-10-23 devnull handler(int s)
169 9acaad45 2004-10-23 devnull {
170 9acaad45 2004-10-23 devnull 	struct sigaction sa;
171 9acaad45 2004-10-23 devnull 
172 9acaad45 2004-10-23 devnull 	sigaction(s, nil, &sa);
173 9acaad45 2004-10-23 devnull 	return sa.sa_handler;
174 9acaad45 2004-10-23 devnull }
175 9acaad45 2004-10-23 devnull 
176 aa200fe3 2004-10-22 devnull static void
177 9acaad45 2004-10-23 devnull notifysetenable(int sig, int enabled)
178 fd04aace 2003-11-23 devnull {
179 9acaad45 2004-10-23 devnull 	sigset_t mask;
180 fd04aace 2003-11-23 devnull 
181 9acaad45 2004-10-23 devnull 	if(sig == 0)
182 aa200fe3 2004-10-22 devnull 		return;
183 aa200fe3 2004-10-22 devnull 
184 9acaad45 2004-10-23 devnull 	sigemptyset(&mask);
185 9acaad45 2004-10-23 devnull 	sigaddset(&mask, sig);
186 9acaad45 2004-10-23 devnull 	sigprocmask(enabled ? SIG_UNBLOCK : SIG_BLOCK, &mask, nil);
187 9acaad45 2004-10-23 devnull }
188 9acaad45 2004-10-23 devnull 
189 9acaad45 2004-10-23 devnull void
190 9acaad45 2004-10-23 devnull notifyenable(char *msg)
191 9acaad45 2004-10-23 devnull {
192 9acaad45 2004-10-23 devnull 	notifyenablex(_p9strsig(msg), 1);
193 9acaad45 2004-10-23 devnull }
194 9acaad45 2004-10-23 devnull 
195 9acaad45 2004-10-23 devnull void
196 9acaad45 2004-10-23 devnull notifydisable(char *msg)
197 9acaad45 2004-10-23 devnull {
198 9acaad45 2004-10-23 devnull 	notifyenablex(_p9strsig(msg), 0);
199 9acaad45 2004-10-23 devnull }
200 9acaad45 2004-10-23 devnull 
201 9acaad45 2004-10-23 devnull static void
202 9acaad45 2004-10-23 devnull notifyseton(int s, int on)
203 9acaad45 2004-10-23 devnull {
204 9acaad45 2004-10-23 devnull 	Sig *sig;
205 9acaad45 2004-10-23 devnull 	struct sigaction sa;
206 9acaad45 2004-10-23 devnull 
207 9acaad45 2004-10-23 devnull 	sig = findsig(s);
208 9acaad45 2004-10-23 devnull 	if(sig == nil)
209 9acaad45 2004-10-23 devnull 		return;
210 9acaad45 2004-10-23 devnull 	notifyenable(msg);
211 669250d1 2003-12-03 devnull 	memset(&sa, 0, sizeof sa);
212 9acaad45 2004-10-23 devnull 	sa.sa_handler = on ? signotify : signonotify;
213 9acaad45 2004-10-23 devnull 	if(sig->restart)
214 9acaad45 2004-10-23 devnull 		sa.sa_flags |= SA_RESTART;
215 aa200fe3 2004-10-22 devnull 
216 aa200fe3 2004-10-22 devnull 	/*
217 9acaad45 2004-10-23 devnull 	 * We can't allow signals within signals because there's
218 9acaad45 2004-10-23 devnull 	 * only one jump buffer.
219 aa200fe3 2004-10-22 devnull 	 */
220 aa200fe3 2004-10-22 devnull 	sigfillset(&sa.sa_mask);
221 9acaad45 2004-10-23 devnull 
222 9acaad45 2004-10-23 devnull 	/*
223 9acaad45 2004-10-23 devnull 	 * Install handler.
224 9acaad45 2004-10-23 devnull 	 */
225 9acaad45 2004-10-23 devnull 	sigaction(sig->sig, &sa, nil);
226 aa200fe3 2004-10-22 devnull }
227 aa200fe3 2004-10-22 devnull 
228 9acaad45 2004-10-23 devnull void
229 9acaad45 2004-10-23 devnull notifyon(char *msg)
230 aa200fe3 2004-10-22 devnull {
231 9acaad45 2004-10-23 devnull 	notifyseton(_p9strsig(msg), 1);
232 fd04aace 2003-11-23 devnull }
233 aa200fe3 2004-10-22 devnull 
234 aa200fe3 2004-10-22 devnull void
235 9acaad45 2004-10-23 devnull notifyoff(char *msg)
236 aa200fe3 2004-10-22 devnull {
237 9acaad45 2004-10-23 devnull 	notifysetoff(_p9strsig(msg), 0);
238 aa200fe3 2004-10-22 devnull }
239 aa200fe3 2004-10-22 devnull 
240 9acaad45 2004-10-23 devnull /*
241 9acaad45 2004-10-23 devnull  * Initialization follows sigs table.
242 9acaad45 2004-10-23 devnull  */
243 9acaad45 2004-10-23 devnull static void
244 9acaad45 2004-10-23 devnull noteinit(void)
245 aa200fe3 2004-10-22 devnull {
246 aa200fe3 2004-10-22 devnull 	int i;
247 9acaad45 2004-10-23 devnull 	Sig *sig;
248 aa200fe3 2004-10-22 devnull 
249 9acaad45 2004-10-23 devnull 	for(i=0; i<nelem(sigs); i++){
250 9acaad45 2004-10-23 devnull 		sig = &sigs[i];
251 9acaad45 2004-10-23 devnull 		/*
252 9acaad45 2004-10-23 devnull 		 * If someone has already installed a handler,
253 9acaad45 2004-10-23 devnull 		 * It's probably some ld preload nonsense,
254 9acaad45 2004-10-23 devnull 		 * like pct (a SIGVTALRM-based profiler).
255 9acaad45 2004-10-23 devnull 		 * Leave it alone.
256 9acaad45 2004-10-23 devnull 		 */
257 9acaad45 2004-10-23 devnull 		if(handler(sig->sig) != SIG_DFL)
258 9acaad45 2004-10-23 devnull 			continue;
259 9acaad45 2004-10-23 devnull 		/*
260 9acaad45 2004-10-23 devnull 		 * Should we only disable and not enable signals?
261 9acaad45 2004-10-23 devnull 		 * (I.e. if parent has disabled for us, should we still enable?)
262 9acaad45 2004-10-23 devnull 		 * Right now we always initialize to the state we want.
263 9acaad45 2004-10-23 devnull 		 */
264 9acaad45 2004-10-23 devnull 		notifysetenable(sig->sig, sig->enabled);
265 9acaad45 2004-10-23 devnull 		notifyseton(sig->sig, sig->notified);
266 9acaad45 2004-10-23 devnull 	}
267 aa200fe3 2004-10-22 devnull }
268 aa200fe3 2004-10-22 devnull