1 #include <u.h>
2 #include <sys/time.h>
3 #include <sys/resource.h>
4 #include "threadimpl.h"
5 
6 #undef waitpid
7 #undef pipe
8 #undef wait
9 
10 static int sigpid;
11 static int threadpassfd = -1;
12 static int gotsigchld;
13 
14 static void
15 child(void)
16 {
17 	int status, pid;
18 	struct rlimit rl;
19 
20 	notedisable("sys: child");
21 	pid = waitpid(sigpid, &status, 0);
22 	if(pid < 0){
23 		fprint(2, "%s: wait: %r\n", argv0);
24 		_exit(97);
25 	}
26 	if(WIFEXITED(status))
27 		 _exit(WEXITSTATUS(status));
28 	if(WIFSIGNALED(status)){
29 		/*
30 		 * Make sure we don't scribble over the nice
31 		 * core file that our child just wrote out.
32 		 */
33 		rl.rlim_cur = 0;
34 		rl.rlim_max = 0;
35 		setrlimit(RLIMIT_CORE, &rl);
36 
37 		signal(WTERMSIG(status), SIG_DFL);
38 		raise(WTERMSIG(status));
39 		_exit(98);	/* not reached */
40 	}
41 	if(WIFSTOPPED(status)){
42 		fprint(2, "%s: wait pid %d stopped\n", argv0, pid);
43 		return;
44 	}
45 #ifdef WIFCONTINUED
46 	if(WIFCONTINUED(status)){
47 		fprint(2, "%s: wait pid %d continued\n", argv0, pid);
48 		return;
49 	}
50 #endif
51 	fprint(2, "%s: wait pid %d status 0x%ux\n", argv0, pid, status);
52 	_exit(99);
53 }
54 
55 static void
56 sigpass(int sig)
57 {
58 	if(sigpid == 1){
59 		gotsigchld = 1;
60 		return;
61 	}
62 
63 	if(sig == SIGCHLD)
64 		child();
65 	else
66 		kill(sigpid, sig);
67 }
68 
69 static int sigs[] =
70 {
71 	SIGHUP, SIGINT, SIGQUIT, SIGILL,
72 	SIGTRAP, SIGABRT, SIGBUS, SIGFPE,
73 	SIGUSR1, SIGSEGV, SIGUSR2, SIGPIPE,
74 	SIGALRM, SIGTERM, SIGCHLD, SIGSTOP,
75 	/*SIGTSTP, SIGTTIN, SIGTTOU,*/ SIGURG,
76 	SIGXCPU, SIGXFSZ, SIGVTALRM, SIGPROF,
77 #ifdef SIGWINCH
78 	SIGWINCH,
79 #endif
80 #ifdef SIGIO
81 	SIGIO,
82 #endif
83 #ifdef SIGEMT
84 	SIGEMT,
85 #endif
86 #ifdef SIGPWR
87 	SIGPWR,
88 #endif
89 #ifdef SIGINFO
90 	SIGINFO,
91 #endif
92 	SIGSYS
93 };
94 
95 void
96 _threadsetupdaemonize(void)
97 {
98 	int i, n, pid;
99 	int p[2];
100 	char buf[20];
101 
102 	sigpid = 1;
103 
104 	/*
105 	 * We've been told this program is likely to background itself.
106 	 * Put it in its own process group so that we don't get a SIGHUP
107 	 * when the parent exits.
108 	 */
109 	setpgid(0, 0);
110 
111 	if(pipe(p) < 0)
112 		sysfatal("passer pipe: %r");
113 
114 	/* hide these somewhere they won't cause harm */
115 	/* can't go too high: NetBSD max is 64, for example */
116 	if(dup(p[0], 28) < 0 || dup(p[1], 29) < 0)
117 		sysfatal("passer pipe dup: %r");
118 	close(p[0]);
119 	close(p[1]);
120 	p[0] = 28;
121 	p[1] = 29;
122 
123 	/* close on exec */
124 	if(fcntl(p[0], F_SETFD, 1) < 0 || fcntl(p[1], F_SETFD, 1) < 0)
125 		sysfatal("passer pipe pipe fcntl: %r");
126 
127 	noteenable("sys: child");
128 	signal(SIGCHLD, sigpass);
129 	switch(pid = fork()){
130 	case -1:
131 		sysfatal("passer fork: %r");
132 	default:
133 		close(p[1]);
134 		break;
135 	case 0:
136 		notedisable("sys: child");
137 		signal(SIGCHLD, SIG_DFL);
138 	/*	rfork(RFNOTEG); */
139 		close(p[0]);
140 		threadpassfd = p[1];
141 		return;
142 	}
143 
144 	sigpid = pid;
145 	if(gotsigchld)
146 		sigpass(SIGCHLD);
147 
148 	for(i=0; i<nelem(sigs); i++){
149 		struct sigaction sa;
150 
151 		memset(&sa, 0, sizeof sa);
152 		sa.sa_handler = sigpass;
153 		sa.sa_flags |= SA_RESTART;
154 		sigaction(sigs[i], &sa, nil);
155 	}
156 
157 	for(;;){
158 		n = read(p[0], buf, sizeof buf-1);
159 		if(n == 0){	/* program exited */
160 			child();
161 		}
162 		if(n > 0)
163 			break;
164 		print("passer read: %r\n");
165 	}
166 	buf[n] = 0;
167 	_exit(atoi(buf));
168 }
169 
170 void
171 _threaddaemonize(void)
172 {
173 	if(threadpassfd < 0)
174 		sysfatal("threads in main proc exited w/o threadmaybackground");
175 	write(threadpassfd, "0", 1);
176 	close(threadpassfd);
177 	threadpassfd = -1;
178 }