1 files changed, 189 insertions, 0 deletions
diff --git a/emu/Plan9/cmd.c b/emu/Plan9/cmd.c
new file mode 100644
index 00000000..8d311f2a
--- /dev/null
+++ b/emu/Plan9/cmd.c
@@ -0,0 +1,189 @@
+#include	"dat.h"
+#include	"fns.h"
+#include	"error.h"
+
+extern	void	vstack(void*);
+
+/*
+ * all this is for the benefit of devcmd.
+ * i hope it's grateful.
+ */
+
+typedef struct Targ Targ;
+struct Targ
+{
+	int	fd[3];	/* standard input, output and error */
+	int	wfd;
+	int*	spin;
+	char**	args;
+	char*	dir;
+	int	pid;
+	int	nice;
+};
+
+/*
+ * called by vstack once it has moved to
+ * the unshared stack in the new process.
+ */
+void
+exectramp(Targ *t)
+{
+	int *fd, i, nfd;
+	char filename[128], err[ERRMAX], status[2*ERRMAX];
+
+	t->pid = getpid();
+	*t->spin = 0;	/* allow parent to proceed: can't just rendezvous: see below */
+	fd = t->fd;
+
+	snprint(filename, sizeof(filename), "#d/%d", t->wfd);
+	t->wfd = open(filename, OWRITE|OCEXEC);
+	/* if it failed, we'll manage */
+
+	nfd = MAXNFD;	/* TO DO: should read from /fd */
+	for(i = 0; i < nfd; i++)
+		if(i != fd[0] && i != fd[1] && i != fd[2] && i != t->wfd)
+			close(i);
+
+	if(fd[0] != 0){
+		dup(fd[0], 0);
+		close(fd[0]);
+	}
+	if(fd[1] != 1){
+		dup(fd[1], 1);
+		close(fd[1]);
+	}
+	if(fd[2] != 2){
+		dup(fd[2], 2);
+		close(fd[2]);
+	}
+
+	if(t->dir != nil && chdir(t->dir) < 0){
+		if(t->wfd > 0)
+			fprint(t->wfd, "chdir: %s: %r", t->dir);
+		_exits("bad dir");
+	}
+	if(t->nice)
+		oslopri();
+
+	exec(t->args[0], t->args);
+	err[0] = 0;
+	errstr(err, sizeof(err));
+	if(t->args[0][0] != '/' && t->args[0][0] != '#' &&
+	   strncmp(t->args[0], "../", 3) != 0 && strncmp(t->args[0], "./", 2) != 0 &&
+	   strlen(t->args[0])+5 < sizeof(filename)){
+		snprint(filename, sizeof(filename), "/bin/%s", t->args[0]);
+		exec(filename, t->args);
+		errstr(err, sizeof(err));
+	}
+	snprint(status, sizeof(status), "%s: can't exec: %s", t->args[0], err);
+	if(t->wfd > 0)
+		write(t->wfd, status, strlen(status));
+	_exits(status);
+}
+
+void*
+oscmd(char **args, int nice, char *dir, int *fd)
+{
+	Targ *t;
+	int spin, *spinptr, fd0[2], fd1[2], fd2[2], wfd[2], n;
+	Dir *d;
+
+	up->genbuf[0] = 0;
+	t = mallocz(sizeof(*t), 1);
+	if(t == nil)
+		return nil;
+	t->args = args;
+	t->dir = dir;
+	t->nice = nice;
+	fd0[0] = fd0[1] = -1;
+	fd1[0] = fd1[1] = -1;
+	fd2[0] = fd2[1] = -1;
+	wfd[0] = wfd[1] = -1;
+	if(dir != nil){
+		d = dirstat(dir);
+		if(d == nil)
+			goto Error;
+		free(d);
+	}
+	if(pipe(fd0) < 0 || pipe(fd1) < 0 || pipe(fd2) < 0 || pipe(wfd) < 0)
+		goto Error;
+
+	spinptr = &spin;
+	spin = 1;
+
+	t->fd[0] = fd0[0];
+	t->fd[1] = fd1[1];
+	t->fd[2] = fd2[1];
+	t->wfd = wfd[1];
+	t->spin = spinptr;
+	switch(rfork(RFPROC|RFMEM|RFREND|RFNOTEG|RFFDG|RFNAMEG|RFENVG)) {
+	case -1:
+		goto Error;
+	case 0:
+		/* if child returns first from rfork, its call to vstack replaces ... */
+		vstack(t);
+		/* ... parent's return address from rfork and parent returns here */
+	default:
+		/* if parent returns first from rfork, it comes here */
+		/* can't call anything: on shared stack until child releases spin in exectramp */
+		while(*spinptr)
+			;
+		break;
+	}
+
+	close(fd0[0]);
+	close(fd1[1]);
+	close(fd2[1]);
+	close(wfd[1]);
+
+	n = read(wfd[0], up->genbuf, sizeof(up->genbuf)-1);
+	close(wfd[0]);
+	if(n > 0){
+		close(fd0[1]);
+		close(fd1[0]);
+		close(fd2[0]);
+		up->genbuf[n] = 0;
+		errstr(up->genbuf, sizeof(up->genbuf));
+		free(t);
+		return nil;
+	}
+
+	fd[0] = fd0[1];
+	fd[1] = fd1[0];
+	fd[2] = fd2[0];
+	return t;
+
+Error:
+	errstr(up->genbuf, sizeof(up->genbuf));	/* save the message before close */
+	close(fd0[0]);
+	close(fd0[1]);
+	close(fd1[0]);
+	close(fd1[1]);
+	close(fd2[0]);
+	close(fd2[1]);
+	close(wfd[0]);
+	close(wfd[1]);
+	free(t);
+	errstr(up->genbuf, sizeof(up->genbuf));
+	return nil;
+}
+
+int
+oscmdkill(void *a)
+{
+	Targ *t = a;
+
+	return postnote(PNGROUP, t->pid, "kill");
+}
+
+int
+oscmdwait(void*, char *buf, int n)
+{
+	return await(buf, n);
+}
+
+void
+oscmdfree(void *a)
+{
+	free(a);
+}