1 #include "threadimpl.h"
2 
3 #define PIPEMNT	"/mnt/temp"
4 
5 void
6 procexec(Channel *pidc, char *prog, char *args[])
7 {
8 	int n;
9 	Proc *p;
10 	Thread *t;
11 
12 	_threaddebug(DBGEXEC, "procexec %s", prog);
13 	/* must be only thread in proc */
14 	p = _threadgetproc();
15 	t = p->thread;
16 	if(p->threads.head != t || p->threads.head->nextt != nil){
17 		werrstr("not only thread in proc");
18 	Bad:
19 		if(pidc)
20 			sendul(pidc, ~0);
21 		return;
22 	}
23 
24 	/*
25 	 * We want procexec to behave like exec; if exec succeeds,
26 	 * never return, and if it fails, return with errstr set.
27 	 * Unfortunately, the exec happens in another proc since
28 	 * we have to wait for the exec'ed process to finish.
29 	 * To provide the semantics, we open a pipe with the 
30 	 * write end close-on-exec and hand it to the proc that
31 	 * is doing the exec.  If the exec succeeds, the pipe will
32 	 * close so that our read below fails.  If the exec fails,
33 	 * then the proc doing the exec sends the errstr down the
34 	 * pipe to us.
35 	 */
36 	if(bind("#|", PIPEMNT, MREPL) < 0)
37 		goto Bad;
38 	if((p->exec.fd[0] = open(PIPEMNT "/data", OREAD)) < 0){
39 		unmount(nil, PIPEMNT);
40 		goto Bad;
41 	}
42 	if((p->exec.fd[1] = open(PIPEMNT "/data1", OWRITE|OCEXEC)) < 0){
43 		close(p->exec.fd[0]);
44 		unmount(nil, PIPEMNT);
45 		goto Bad;
46 	}
47 	unmount(nil, PIPEMNT);
48 
49 	/* exec in parallel via the scheduler */
50 	assert(p->needexec==0);
51 	p->exec.prog = prog;
52 	p->exec.args = args;
53 	p->needexec = 1;
54 	_sched();
55 
56 	close(p->exec.fd[1]);
57 	if((n = read(p->exec.fd[0], p->exitstr, ERRMAX-1)) > 0){	/* exec failed */
58 		p->exitstr[n] = '\0';
59 		errstr(p->exitstr, ERRMAX);
60 		close(p->exec.fd[0]);
61 		goto Bad;
62 	}
63 	close(p->exec.fd[0]);
64 
65 	if(pidc)
66 		sendul(pidc, t->ret);
67 
68 	/* wait for exec'ed program, then exit */
69 	_schedexecwait();
70 }
71 
72 void
73 procexecl(Channel *pidc, char *f, ...)
74 {
75 	procexec(pidc, f, &f+1);
76 }
77