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Date:: Mon Dec 27 03:22:54 2004 UTC
Message:: as wkj pointed out, notifyseton should not call notesetenable
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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 5f8fa947 2004-12-26 devnull  * We do not handle SIGABRT or SIGSEGV, mainly because
 11 5f8fa947 2004-12-26 devnull  * the thread library queues its notes for later, and we want
 12 5f8fa947 2004-12-26 devnull  * to dump core with the state at time of delivery.
 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 	char tmp[64];
116 05d8c6df 2004-09-23 devnull 	Jmp *j;
117 fd04aace 2003-11-23 devnull 
118 05d8c6df 2004-09-23 devnull 	j = (*_notejmpbuf)();
119 9acaad45 2004-10-23 devnull 	switch(p9setjmp(j->b)){
120 9acaad45 2004-10-23 devnull 	case 0:
121 9acaad45 2004-10-23 devnull 		if(notifyf)
122 9acaad45 2004-10-23 devnull 			(*notifyf)(nil, _p9sigstr(sig, tmp));
123 9acaad45 2004-10-23 devnull 		/* fall through */
124 9acaad45 2004-10-23 devnull 	case 1:	/* noted(NDFLT) */
125 9acaad45 2004-10-23 devnull 		if(0)print("DEFAULT %d\n", sig);
126 9acaad45 2004-10-23 devnull 		signal(sig, SIG_DFL);
127 9acaad45 2004-10-23 devnull 		raise(sig);
128 9acaad45 2004-10-23 devnull 		_exit(1);
129 9acaad45 2004-10-23 devnull 	case 2:	/* noted(NCONT) */
130 05d8c6df 2004-09-23 devnull 		if(0)print("HANDLED %d\n", sig);
131 fd04aace 2003-11-23 devnull 		return;
132 fd04aace 2003-11-23 devnull 	}
133 fd04aace 2003-11-23 devnull }
134 05d8c6df 2004-09-23 devnull 
135 9acaad45 2004-10-23 devnull static void
136 9acaad45 2004-10-23 devnull signonotify(int sig)
137 9acaad45 2004-10-23 devnull {
138 9acaad45 2004-10-23 devnull 	USED(sig);
139 9acaad45 2004-10-23 devnull }
140 9acaad45 2004-10-23 devnull 
141 fd04aace 2003-11-23 devnull int
142 05d8c6df 2004-09-23 devnull noted(int v)
143 05d8c6df 2004-09-23 devnull {
144 05d8c6df 2004-09-23 devnull 	p9longjmp((*_notejmpbuf)()->b, v==NCONT ? 2 : 1);
145 05d8c6df 2004-09-23 devnull 	abort();
146 05d8c6df 2004-09-23 devnull 	return 0;
147 05d8c6df 2004-09-23 devnull }
148 05d8c6df 2004-09-23 devnull 
149 9acaad45 2004-10-23 devnull int
150 9acaad45 2004-10-23 devnull notify(void (*f)(void*, char*))
151 9acaad45 2004-10-23 devnull {
152 9acaad45 2004-10-23 devnull 	static int init;
153 9acaad45 2004-10-23 devnull 
154 9acaad45 2004-10-23 devnull 	notifyf = f;
155 9acaad45 2004-10-23 devnull 	if(!init){
156 9acaad45 2004-10-23 devnull 		init = 1;
157 9acaad45 2004-10-23 devnull 		noteinit();
158 9acaad45 2004-10-23 devnull 	}
159 9acaad45 2004-10-23 devnull 	return 0;
160 9acaad45 2004-10-23 devnull }
161 9acaad45 2004-10-23 devnull 
162 9acaad45 2004-10-23 devnull /*
163 9acaad45 2004-10-23 devnull  * Nonsense about enabling and disabling signals.
164 9acaad45 2004-10-23 devnull  */
165 5f8fa947 2004-12-26 devnull typedef void Sighandler(int);
166 5f8fa947 2004-12-26 devnull static Sighandler*
167 9acaad45 2004-10-23 devnull handler(int s)
168 9acaad45 2004-10-23 devnull {
169 9acaad45 2004-10-23 devnull 	struct sigaction sa;
170 9acaad45 2004-10-23 devnull 
171 9acaad45 2004-10-23 devnull 	sigaction(s, nil, &sa);
172 9acaad45 2004-10-23 devnull 	return sa.sa_handler;
173 9acaad45 2004-10-23 devnull }
174 9acaad45 2004-10-23 devnull 
175 aa200fe3 2004-10-22 devnull static void
176 5f8fa947 2004-12-26 devnull notesetenable(int sig, int enabled)
177 fd04aace 2003-11-23 devnull {
178 9acaad45 2004-10-23 devnull 	sigset_t mask;
179 fd04aace 2003-11-23 devnull 
180 9acaad45 2004-10-23 devnull 	if(sig == 0)
181 aa200fe3 2004-10-22 devnull 		return;
182 aa200fe3 2004-10-22 devnull 
183 9acaad45 2004-10-23 devnull 	sigemptyset(&mask);
184 9acaad45 2004-10-23 devnull 	sigaddset(&mask, sig);
185 9acaad45 2004-10-23 devnull 	sigprocmask(enabled ? SIG_UNBLOCK : SIG_BLOCK, &mask, nil);
186 9acaad45 2004-10-23 devnull }
187 9acaad45 2004-10-23 devnull 
188 9acaad45 2004-10-23 devnull void
189 5f8fa947 2004-12-26 devnull noteenable(char *msg)
190 9acaad45 2004-10-23 devnull {
191 5f8fa947 2004-12-26 devnull 	notesetenable(_p9strsig(msg), 1);
192 9acaad45 2004-10-23 devnull }
193 9acaad45 2004-10-23 devnull 
194 9acaad45 2004-10-23 devnull void
195 5f8fa947 2004-12-26 devnull notedisable(char *msg)
196 9acaad45 2004-10-23 devnull {
197 5f8fa947 2004-12-26 devnull 	notesetenable(_p9strsig(msg), 0);
198 9acaad45 2004-10-23 devnull }
199 9acaad45 2004-10-23 devnull 
200 9acaad45 2004-10-23 devnull static void
201 9acaad45 2004-10-23 devnull notifyseton(int s, int on)
202 9acaad45 2004-10-23 devnull {
203 9acaad45 2004-10-23 devnull 	Sig *sig;
204 9acaad45 2004-10-23 devnull 	struct sigaction sa;
205 9acaad45 2004-10-23 devnull 
206 9acaad45 2004-10-23 devnull 	sig = findsig(s);
207 9acaad45 2004-10-23 devnull 	if(sig == nil)
208 9acaad45 2004-10-23 devnull 		return;
209 669250d1 2003-12-03 devnull 	memset(&sa, 0, sizeof sa);
210 9acaad45 2004-10-23 devnull 	sa.sa_handler = on ? signotify : signonotify;
211 9acaad45 2004-10-23 devnull 	if(sig->restart)
212 9acaad45 2004-10-23 devnull 		sa.sa_flags |= SA_RESTART;
213 aa200fe3 2004-10-22 devnull 
214 aa200fe3 2004-10-22 devnull 	/*
215 9acaad45 2004-10-23 devnull 	 * We can't allow signals within signals because there's
216 9acaad45 2004-10-23 devnull 	 * only one jump buffer.
217 aa200fe3 2004-10-22 devnull 	 */
218 aa200fe3 2004-10-22 devnull 	sigfillset(&sa.sa_mask);
219 9acaad45 2004-10-23 devnull 
220 9acaad45 2004-10-23 devnull 	/*
221 9acaad45 2004-10-23 devnull 	 * Install handler.
222 9acaad45 2004-10-23 devnull 	 */
223 9acaad45 2004-10-23 devnull 	sigaction(sig->sig, &sa, nil);
224 aa200fe3 2004-10-22 devnull }
225 aa200fe3 2004-10-22 devnull 
226 9acaad45 2004-10-23 devnull void
227 9acaad45 2004-10-23 devnull notifyon(char *msg)
228 aa200fe3 2004-10-22 devnull {
229 9acaad45 2004-10-23 devnull 	notifyseton(_p9strsig(msg), 1);
230 fd04aace 2003-11-23 devnull }
231 aa200fe3 2004-10-22 devnull 
232 aa200fe3 2004-10-22 devnull void
233 9acaad45 2004-10-23 devnull notifyoff(char *msg)
234 aa200fe3 2004-10-22 devnull {
235 5f8fa947 2004-12-26 devnull 	notifyseton(_p9strsig(msg), 0);
236 aa200fe3 2004-10-22 devnull }
237 aa200fe3 2004-10-22 devnull 
238 9acaad45 2004-10-23 devnull /*
239 9acaad45 2004-10-23 devnull  * Initialization follows sigs table.
240 9acaad45 2004-10-23 devnull  */
241 9acaad45 2004-10-23 devnull static void
242 9acaad45 2004-10-23 devnull noteinit(void)
243 aa200fe3 2004-10-22 devnull {
244 aa200fe3 2004-10-22 devnull 	int i;
245 9acaad45 2004-10-23 devnull 	Sig *sig;
246 aa200fe3 2004-10-22 devnull 
247 9acaad45 2004-10-23 devnull 	for(i=0; i<nelem(sigs); i++){
248 9acaad45 2004-10-23 devnull 		sig = &sigs[i];
249 9acaad45 2004-10-23 devnull 		/*
250 9acaad45 2004-10-23 devnull 		 * If someone has already installed a handler,
251 9acaad45 2004-10-23 devnull 		 * It's probably some ld preload nonsense,
252 9acaad45 2004-10-23 devnull 		 * like pct (a SIGVTALRM-based profiler).
253 5f8fa947 2004-12-26 devnull 		 * Or maybe someone has already called notifyon/notifyoff.
254 9acaad45 2004-10-23 devnull 		 * Leave it alone.
255 9acaad45 2004-10-23 devnull 		 */
256 9acaad45 2004-10-23 devnull 		if(handler(sig->sig) != SIG_DFL)
257 9acaad45 2004-10-23 devnull 			continue;
258 9acaad45 2004-10-23 devnull 		/*
259 9acaad45 2004-10-23 devnull 		 * Should we only disable and not enable signals?
260 9acaad45 2004-10-23 devnull 		 * (I.e. if parent has disabled for us, should we still enable?)
261 9acaad45 2004-10-23 devnull 		 * Right now we always initialize to the state we want.
262 9acaad45 2004-10-23 devnull 		 */
263 5f8fa947 2004-12-26 devnull 		notesetenable(sig->sig, sig->enabled);
264 9acaad45 2004-10-23 devnull 		notifyseton(sig->sig, sig->notified);
265 9acaad45 2004-10-23 devnull 	}
266 aa200fe3 2004-10-22 devnull }
267 aa200fe3 2004-10-22 devnull