implement B; include "sys.m";include "draw.m";include "workdir.m"; FD: import Sys;Context: import Draw; B: module{	init:	fn(nil: ref Context, argv: list of string);}; sys: Sys;stderr: ref FD;wkdir: string; init(nil: ref Context, argv: list of string){	sys = load Sys Sys->PATH;	stderr = sys->fildes(2); 	if(len argv < 2) {		sys->fprint(stderr, "Usage: B file ...\n");		return;	}	argv = tl argv; 	cmd := "exec B ";	while(argv != nil) {		f := hd argv;		if(len f > 0 && f[0] != '/' && f[0] != '-')			f = wd() + f;		cmd += "/usr/inferno"+f;		argv = tl argv;		if(argv != nil)			cmd += " ";	}				cfd := sys->open("/cmd/clone", sys->ORDWR);	if(cfd == nil) {		sys->fprint(stderr, "B: open /cmd/clone: %r\n");		return;	}		buf := array[32] of byte;	n := sys->read(cfd, buf, len buf);	if(n <= 0) {		sys->fprint(stderr, "B: read /cmd/#/ctl: %r\n");		return;	}	dir := "/cmd/"+string buf[0:n]; 	# Start the Command	n = sys->fprint(cfd, "%s", cmd);	if(n <= 0) {		sys->fprint(stderr, "B: exec: %r\n");		return;	} 	io := sys->open(dir+"/data", sys->ORDWR);	if(io == nil) {		sys->fprint(stderr, "B: open /cmd/#/data: %r\n");		return;	} 	sys->pctl(sys->NEWPGRP, nil);	copy(io, sys->fildes(1), nil);} wd(): string{	if(wkdir != nil)		return wkdir; 	gwd := load Workdir Workdir->PATH; 	wkdir = gwd->init();	if(wkdir == nil) {		sys->fprint(stderr, "B: can't get working dir: %r");		exit;	}	wkdir = wkdir+"/";	return wkdir;} copy(f, t: ref FD, c: chan of int){	if(c != nil)		c <-= sys->pctl(0, nil); 	buf := array[8192] of byte;	for(;;) {		r := sys->read(f, buf, len buf);		if(r <= 0)			break;		w := sys->write(t, buf, r);		if(w != r)			break;	}} kill(pid: int){	fd := sys->open("/prog/"+string pid+"/ctl", sys->OWRITE);	sys->fprint(fd, "kill");}