New thread library

src/libthread/exec.c

@@ -0,0 +1,153 @@
+#include "u.h"
+#include <errno.h>
+#include "libc.h"
+#include "thread.h"
+#include "threadimpl.h"
+
+static Lock thewaitlock;
+static Channel *thewaitchan;
+static Channel *dowaitchan;
+
+/* BUG - start waitproc on first exec, not when threadwaitchan is called */
+static void
+waitproc(void *v)
+{
+	Channel *c;
+	Waitmsg *w;
+
+	_threadsetsysproc();
+	for(;;){
+		while((w = wait()) == nil){
+			if(errno == ECHILD)
+				recvul(dowaitchan);
+		}
+		if((c = thewaitchan) != nil)
+			sendp(c, w);
+		else
+			free(w);
+	}
+}
+
+Channel*
+threadwaitchan(void)
+{
+	if(thewaitchan)
+		return thewaitchan;
+	lock(&thewaitlock);
+	if(thewaitchan){
+		unlock(&thewaitlock);
+		return thewaitchan;
+	}
+	thewaitchan = chancreate(sizeof(Waitmsg*), 4);
+	chansetname(thewaitchan, "threadwaitchan");
+	dowaitchan = chancreate(sizeof(ulong), 1);
+	chansetname(dowaitchan, "dowaitchan");
+	proccreate(waitproc, nil, STACK);
+	unlock(&thewaitlock);
+	return thewaitchan;
+}
+
+int
+threadspawn(int fd[3], char *cmd, char *argv[])
+{
+	int i, n, p[2], pid;
+	char exitstr[100];
+
+	if(pipe(p) < 0)
+		return -1;
+	if(fcntl(p[0], F_SETFD, 1) < 0 || fcntl(p[1], F_SETFD, 1) < 0){
+		close(p[0]);
+		close(p[1]);
+		return -1;
+	}
+	switch(pid = fork()){
+	case -1:
+		close(p[0]);
+		close(p[1]);
+		return -1;
+	case 0:
+		dup2(fd[0], 0);
+		dup2(fd[1], 1);
+		dup2(fd[2], 2);
+		for(i=3; i<100; i++)
+			if(i != p[1])
+				close(i);
+		execvp(cmd, argv);
+		fprint(p[1], "%d", errno);
+		close(p[1]);
+		_exit(0);
+	}
+
+	close(p[1]);
+	n = read(p[0], exitstr, sizeof exitstr-1);
+	close(p[0]);
+	if(n > 0){	/* exec failed */
+		exitstr[n] = 0;
+		errno = atoi(exitstr);
+		return -1;
+	}
+
+	close(fd[0]);
+	if(fd[1] != fd[0])
+		close(fd[1]);
+	if(fd[2] != fd[1] && fd[2] != fd[0])
+		close(fd[2]);
+	channbsendul(dowaitchan, 1);
+	return pid;
+}
+
+int
+_threadexec(Channel *cpid, int fd[3], char *cmd, char *argv[])
+{
+	int pid;
+
+	pid = threadspawn(fd, cmd, argv);
+	if(cpid){
+		if(pid < 0)
+			chansendul(cpid, ~0);
+		else
+			chansendul(cpid, pid);
+	}
+	return pid;
+}
+
+void
+threadexec(Channel *cpid, int fd[3], char *cmd, char *argv[])
+{
+	if(_threadexec(cpid, fd, cmd, argv) >= 0)
+		threadexits("threadexec");
+}
+
+void
+threadexecl(Channel *cpid, int fd[3], char *cmd, ...)
+{
+	char **argv, *s;
+	int n, pid;
+	va_list arg;
+
+	va_start(arg, cmd);
+	for(n=0; va_arg(arg, char*) != nil; n++)
+		;
+	n++;
+	va_end(arg);
+
+	argv = malloc(n*sizeof(argv[0]));
+	if(argv == nil){
+		if(cpid)
+			chansendul(cpid, ~0);
+		return;
+	}
+
+	va_start(arg, cmd);
+	for(n=0; (s=va_arg(arg, char*)) != nil; n++)
+		argv[n] = s;
+	argv[n] = 0;
+	va_end(arg);
+
+	pid = _threadexec(cpid, fd, cmd, argv);
+	free(argv);
+
+	if(pid >= 0)
+		threadexits("threadexecl");
+}
+