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Spork returns an error code now.

    We can fail gracefully. Do so.

--- a/libstd/spork.myr

+++ b/libstd/spork.myr

@@ -3,33 +3,37 @@

 use "die.use"

 use "execvp.use"

 use "fmt.use"

+use "result.use"

 use "syswrap.use"

 pkg std =

-	const spork	: (cmd : byte[:][:]	-> (pid, fd, fd))

-	const sporkfd	: (cmd : byte[:][:], infd : fd, outfd : fd	-> pid)

+	const spork	: (cmd : byte[:][:]	-> result((pid, fd, fd), int))

+	const sporkfd	: (cmd : byte[:][:], infd : fd, outfd : fd	-> result(pid, int))

 ;;

 const spork = {cmd

 	var infds  :fd[2], outfds : fd[2]

 	var err

-	var pid

 	/* open up pipes */

 	err = pipe(&infds)

 	if err != 0

-		fatal(1, "Could not create pipes: err %l\n", -err)

+		-> `Fail (-err castto(int))

 	;;

 	err = pipe(&outfds)

 	if err != 0

-		fatal(1, "Could not create pipes: err %l\n", -err)

+		-> `Fail (-err castto(int))

 	;;

-	pid = sporkfd(cmd, infds[0] castto(fd), outfds[1] castto(fd))

-	/* close unused fd ends */

-	close(infds[0]);

-	close(outfds[1]);

-	-> (pid, infds[1], outfds[0])

+	match sporkfd(cmd, infds[0] castto(fd), outfds[1] castto(fd))

+	| `Ok pid:

+		/* close unused fd ends */

+		close(infds[0]);

+		close(outfds[1]);

+		-> `Ok (pid, infds[1], outfds[0])

+	| `Fail m:

+		-> `Fail m

+	;;

 }

 const sporkfd = {cmd, infd, outfd

@@ -38,7 +42,7 @@

 	pid = fork()

 	/* error  */

 	if pid == -1

-		fatal(1, "Could not fork to start slave\n")

+		-> `Fail -1

 	/* child */

 	elif pid == 0

 		/* stdin/stdout for our communication. */

@@ -55,7 +59,7 @@

 		;;

 	/* parent */

 	else

-		-> pid castto(pid)

+		-> `Ok pid

 	;;

 }