implement Runas; include "sys.m";include "draw.m";include "sh.m"; sys: Sys;sh: Sh; Context: import sh; Runas: module {	init: fn(nil: ref Draw->Context, argv: list of string);}; init(drawctxt: ref Draw->Context, argv: list of string){	sys = load Sys Sys->PATH;	sh = load Sh Sh->PATH;	if (sh == nil)		badmodule(Sh->PATH); 	if (len argv < 3)		usage(); 	argv = tl argv;	user := hd argv;	argv = tl argv; 	fd := sys->open("/dev/user", Sys->OWRITE);	if (fd == nil)		error(sys->sprint("cannot open /dev/user: %r"));	u := array of byte user;	if (sys->write(fd, u, len u) != len u)		error(sys->sprint("cannot set user: %r"));	sh->run(drawctxt, argv);} badmodule(p: string){	sys->fprint(stderr(), "runas: cannot load %s: %r\n", p);	raise "fail:bad module";} stderr(): ref Sys->FD{	return sys->fildes(2);} usage(){	sys->fprint(stderr(), "usage: runas user cmd [args...]\n");	raise "fail:usage";} error(e: string){	sys->fprint(stderr(), "runas: %s\n", e);	raise "fail:error";}