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;
12 
13 static void
14 child(void)
15 {
16 	int status, pid;
17 	struct rlimit rl;
18 
19 	notedisable("sys: child");
20 	pid = waitpid(sigpid, &status, 0);
21 	if(pid < 0){
22 		fprint(2, "%s: wait: %r\n", argv0);
23 		_exit(97);
24 	}
25 	if(WIFEXITED(status))
26 		 _exit(WEXITSTATUS(status));
27 	if(WIFSIGNALED(status)){
28 		/*
29 		 * Make sure we don't scribble over the nice
30 		 * core file that our child just wrote out.
31 		 */
32 		rl.rlim_cur = 0;
33 		rl.rlim_max = 0;
34 		setrlimit(RLIMIT_CORE, &rl);
35 
36 		signal(WTERMSIG(status), SIG_DFL);
37 		raise(WTERMSIG(status));
38 		_exit(98);	/* not reached */
39 	}
40 	fprint(2, "%s: wait pid %d status 0x%ux\n", pid, status);
41 	_exit(99);
42 }
43 
44 static void
45 sigpass(int sig)
46 {
47 	if(sig == SIGCHLD)
48 		child();
49 	else
50 		kill(sigpid, sig);
51 }
52 
53 void
54 _threadsetupdaemonize(void)
55 {
56 	int i, n, pid;
57 	int p[2];
58 	char buf[20];
59 
60 	sigpid = 1;
61 
62 	threadlinklibrary();
63 
64 	if(pipe(p) < 0)
65 		sysfatal("passer pipe: %r");
66 
67 	/* hide these somewhere they won't cause harm */
68 	if(dup(p[0], 98) < 0 || dup(p[1], 99) < 0)
69 		sysfatal("passer pipe dup: %r");
70 	close(p[0]);
71 	close(p[1]);
72 	p[0] = 98;
73 	p[1] = 99;
74 
75 	/* close on exec */
76 	if(fcntl(p[0], F_SETFD, 1) < 0 || fcntl(p[1], F_SETFD, 1) < 0)
77 		sysfatal("passer pipe pipe fcntl: %r");
78 
79 	noteenable("sys: child");
80 	signal(SIGCHLD, sigpass);
81 	switch(pid = fork()){
82 	case -1:
83 		sysfatal("passer fork: %r");
84 	default:
85 		close(p[1]);
86 		break;
87 	case 0:
88 		for(i=0; i<100; i++) sched_yield();
89 		notedisable("sys: child");
90 		signal(SIGCHLD, SIG_DFL);
91 		rfork(RFNOTEG);
92 		close(p[0]);
93 		threadpassfd = p[1];
94 		return;
95 	}
96 
97 	sigpid = pid;
98 	for(i=0; i<NSIG; i++){
99 		struct sigaction sa;
100 
101 		memset(&sa, 0, sizeof sa);
102 		sa.sa_handler = sigpass;
103 		sa.sa_flags |= SA_RESTART;
104 		sigaction(i, &sa, nil);
105 	}
106 
107 	for(;;){
108 		n = read(p[0], buf, sizeof buf-1);
109 		if(n == 0){	/* program exited */
110 			child();
111 		}
112 		if(n > 0)
113 			break;
114 		print("passer read: %r\n");
115 	}
116 	buf[n] = 0;
117 	_exit(atoi(buf));
118 }
119 
120 void
121 _threaddaemonize(void)
122 {
123 	if(threadpassfd >= 0){
124 		write(threadpassfd, "0", 1);
125 		close(threadpassfd);
126 		threadpassfd = -1;
127 	}
128 }