1 #include "u.h"
2 #include <errno.h>
3 #include "libc.h"
4 #include "thread.h"
5 #include "threadimpl.h"
6 
7 static Lock thewaitlock;
8 static Channel *thewaitchan;
9 static Channel *dowaitchan;
10 
11 /* BUG - start waitproc on first exec, not when threadwaitchan is called */
12 static void
13 waitproc(void *v)
14 {
15 	Channel *c;
16 	Waitmsg *w;
17 
18 	_threadsetsysproc();
19 	for(;;){
20 		while((w = wait()) == nil){
21 			if(errno == ECHILD)
22 				recvul(dowaitchan);
23 		}
24 		if((c = thewaitchan) != nil)
25 			sendp(c, w);
26 		else
27 			free(w);
28 	}
29 }
30 
31 Channel*
32 threadwaitchan(void)
33 {
34 	if(thewaitchan)
35 		return thewaitchan;
36 	lock(&thewaitlock);
37 	if(thewaitchan){
38 		unlock(&thewaitlock);
39 		return thewaitchan;
40 	}
41 	thewaitchan = chancreate(sizeof(Waitmsg*), 4);
42 	chansetname(thewaitchan, "threadwaitchan");
43 	dowaitchan = chancreate(sizeof(ulong), 1);
44 	chansetname(dowaitchan, "dowaitchan");
45 	proccreate(waitproc, nil, STACK);
46 	unlock(&thewaitlock);
47 	return thewaitchan;
48 }
49 
50 int
51 threadspawn(int fd[3], char *cmd, char *argv[])
52 {
53 	int i, n, p[2], pid;
54 	char exitstr[100];
55 
56 	if(pipe(p) < 0)
57 		return -1;
58 	if(fcntl(p[0], F_SETFD, 1) < 0 || fcntl(p[1], F_SETFD, 1) < 0){
59 		close(p[0]);
60 		close(p[1]);
61 		return -1;
62 	}
63 	switch(pid = fork()){
64 	case -1:
65 		close(p[0]);
66 		close(p[1]);
67 		return -1;
68 	case 0:
69 		dup2(fd[0], 0);
70 		dup2(fd[1], 1);
71 		dup2(fd[2], 2);
72 		for(i=3; i<100; i++)
73 			if(i != p[1])
74 				close(i);
75 		execvp(cmd, argv);
76 		fprint(p[1], "%d", errno);
77 		close(p[1]);
78 		_exit(0);
79 	}
80 
81 	close(p[1]);
82 	n = read(p[0], exitstr, sizeof exitstr-1);
83 	close(p[0]);
84 	if(n > 0){	/* exec failed */
85 		exitstr[n] = 0;
86 		errno = atoi(exitstr);
87 		return -1;
88 	}
89 
90 	close(fd[0]);
91 	if(fd[1] != fd[0])
92 		close(fd[1]);
93 	if(fd[2] != fd[1] && fd[2] != fd[0])
94 		close(fd[2]);
95 	channbsendul(dowaitchan, 1);
96 	return pid;
97 }
98 
99 int
100 _threadexec(Channel *cpid, int fd[3], char *cmd, char *argv[])
101 {
102 	int pid;
103 
104 	pid = threadspawn(fd, cmd, argv);
105 	if(cpid){
106 		if(pid < 0)
107 			chansendul(cpid, ~0);
108 		else
109 			chansendul(cpid, pid);
110 	}
111 	return pid;
112 }
113 
114 void
115 threadexec(Channel *cpid, int fd[3], char *cmd, char *argv[])
116 {
117 	if(_threadexec(cpid, fd, cmd, argv) >= 0)
118 		threadexits("threadexec");
119 }
120 
121 void
122 threadexecl(Channel *cpid, int fd[3], char *cmd, ...)
123 {
124 	char **argv, *s;
125 	int n, pid;
126 	va_list arg;
127 
128 	va_start(arg, cmd);
129 	for(n=0; va_arg(arg, char*) != nil; n++)
130 		;
131 	n++;
132 	va_end(arg);
133 
134 	argv = malloc(n*sizeof(argv[0]));
135 	if(argv == nil){
136 		if(cpid)
137 			chansendul(cpid, ~0);
138 		return;
139 	}
140 
141 	va_start(arg, cmd);
142 	for(n=0; (s=va_arg(arg, char*)) != nil; n++)
143 		argv[n] = s;
144 	argv[n] = 0;
145 	va_end(arg);
146 
147 	pid = _threadexec(cpid, fd, cmd, argv);
148 	free(argv);
149 
150 	if(pid >= 0)
151 		threadexits("threadexecl");
152 }
153