implement CPU; include "sys.m";	sys: Sys;	stderr: ref Sys->FD;include "draw.m";	Context: import Draw;include "string.m";	str: String;include "arg.m";include "keyring.m";include "security.m"; DEFCMD:	con "/dis/sh"; CPU: module{	init:	fn(ctxt: ref Context, argv: list of string);}; badmodule(p: string){	sys->fprint(stderr, "cpu: cannot load %s: %r\n", p);	raise "fail:bad module";} usage(){	sys->fprint(stderr, "Usage: cpu [-C cryptoalg] mach command args...\n");	raise "fail:usage";} # The default level of security is NOSSL, unless# the keyring directory doesn't exist, in which case# it's disallowed.init(nil: ref Context, argv: list of string){	sys = load Sys Sys->PATH;	stderr = sys->fildes(2); 	arg := load Arg Arg->PATH;	if (arg == nil) badmodule(Arg->PATH); 	str = load String String->PATH;	if (str == nil) badmodule(String->PATH); 	au := load Auth Auth->PATH;	if (au == nil) badmodule(Auth->PATH); 	kr := load Keyring Keyring->PATH;	if (kr == nil) badmodule(Keyring->PATH); 	arg->init(argv);	alg := "";	while ((opt := arg->opt()) != 0) {		if (opt == 'C') {			alg = arg->arg();		} else			usage();	}	argv = arg->argv();	args := "auxi/cpuslave";#	if(ctxt != nil && ctxt.screen != nil)#		args += " -s" + string ctxt.screen.id;#	else		args += " --"; 	mach: string;	case len argv {	0 =>		usage();	1 =>		mach = hd argv;		args += " " + DEFCMD;	* =>		mach = hd argv;		args += " " + str->quoted(tl argv);	} 	user := getuser();	kd := "/usr/" + user + "/keyring/";	cert := kd + netmkaddr(mach, "tcp", "");	if (!exists(cert)) {		cert = kd + "default";		if (!exists(cert)) {			sys->fprint(stderr, "cpu: cannot find certificate in %s; use getauthinfo\n", kd);			raise "fail:no certificate";		}	} 	# To make visible remotely	if(!exists("/dev/draw/new"))		sys->bind("#d", "/dev", Sys->MBEFORE); 	(ok, c) := sys->dial(netmkaddr(mach, "net", "rstyx"), nil);	if(ok < 0){		sys->fprint(stderr, "Error: cpu: dial: %r\n");		return;	} 	ai := kr->readauthinfo(cert); 	if (alg == nil)		alg = "none";	err := au->init();	if(err != nil) {		sys->fprint(stderr, "cpu: cannot initialise auth module: %s\n", err);		raise "fail:auth init failed";	} 	fd := ref Sys->FD;	#sys->fprint(stderr, "cpu: authenticating using alg '%s'\n", alg);			(fd, err) = au->client(alg, ai, c.dfd);	if(fd == nil) {		sys->fprint(stderr, "cpu: authentication failed: %s\n", err);		raise "fail:authentication failure";	} 	t := array of byte sys->sprint("%d\n%s\n", len (array of byte args)+1, args);	if(sys->write(fd, t, len t) != len t){		sys->fprint(stderr, "cpu: export args write error: %r\n");		raise "fail:write error";	} 	if(sys->export(fd, "/", sys->EXPWAIT) < 0){		sys->fprint(stderr, "cpu: export failed: %r\n");		raise "fail:export error";	}} exists(file: string): int{	(ok, nil) := sys->stat(file);	return ok != -1;} getuser(): string{	fd := sys->open("/dev/user", sys->OREAD);	if(fd == nil){		sys->fprint(stderr, "cpu: cannot open /dev/user: %r\n");		raise "fail:no user id";	} 	buf := array[50] of byte;	n := sys->read(fd, buf, len buf);	if(n < 0){		sys->fprint(stderr, "cpu: cannot read /dev/user: %r\n");		raise "fail:no user id";	} 	return string buf[0:n];	} netmkaddr(addr, net, svc: string): string{	if(net == nil)		net = "net";	(n, nil) := sys->tokenize(addr, "!");	if(n <= 1){		if(svc== nil)			return sys->sprint("%s!%s", net, addr);		return sys->sprint("%s!%s!%s", net, addr, svc);	}	if(svc == nil || n > 2)		return addr;	return sys->sprint("%s!%s", addr, svc);}