implement Mntgen;include "sys.m";	sys: Sys;include "draw.m";include "styx.m";	styx: Styx;	Rmsg, Tmsg: import styx;include "styxservers.m";	styxservers: Styxservers;	Ebadfid, Enotfound, Eopen, Einuse: import Styxservers;	Styxserver, readbytes, Navigator, Fid: import styxservers; 	nametree: Nametree;	Tree: import nametree; Mntgen: module {	init: fn(nil: ref Draw->Context, argv: list of string);}; Qroot: con big 16rfffffff; badmodule(p: string){	sys->fprint(sys->fildes(2), "cannot load %s: %r\n", p);	raise "fail:bad module";}DEBUG: con 0; Entry: adt {	refcount: int;	path: big;};refcounts := array[10] of Entry;tree: ref Tree;nav: ref Navigator; uniq: int; init(nil: ref Draw->Context, nil: list of string){	sys = load Sys Sys->PATH;	styx = load Styx Styx->PATH;	if (styx == nil)		badmodule(Styx->PATH);	styx->init();	styxservers = load Styxservers Styxservers->PATH;	if (styxservers == nil)		badmodule(Styxservers->PATH);	styxservers->init(styx); 	nametree = load Nametree Nametree->PATH;	if (nametree == nil)		badmodule(Nametree->PATH);	nametree->init(); 	navop: chan of ref Styxservers->Navop;	(tree, navop) = nametree->start();	nav = Navigator.new(navop);	(tchan, srv) := Styxserver.new(sys->fildes(0), nav, Qroot); 	tree.create(Qroot, dir(".", Sys->DMDIR | 8r555, Qroot)); 	for (;;) {		gm := <-tchan;		if (gm == nil) {			tree.quit();			exit;		}		e := handlemsg(gm, srv, tree);		if (e != nil)			srv.reply(ref Rmsg.Error(gm.tag, e));	}} walk1(c: ref Fid, name: string): string{	if (name == ".."){		if (c.path != Qroot)			decref(c.path);		c.walk(Sys->Qid(Qroot, 0, Sys->QTDIR));	} else if (c.path == Qroot) {		(d, nil) := nav.walk(c.path, name);		if (d == nil)			d = addentry(name);		else			incref(d.qid.path);		c.walk(d.qid);	} else		return Enotfound;	return nil;} handlemsg(gm: ref Styx->Tmsg, srv: ref Styxserver, nil: ref Tree): string{	pick m := gm {	Walk =>		c := srv.getfid(m.fid);		if(c == nil)			return Ebadfid;		if(c.isopen)			return Eopen;		if(m.newfid != m.fid){			nc := srv.newfid(m.newfid);			if(nc == nil)				return Einuse;			c = c.clone(nc);			incref(c.path);		}		qids := array[len m.names] of Sys->Qid;		oldpath := c.path;		oldqtype := c.qtype;		incref(oldpath);		for (i := 0; i < len m.names; i++){			err := walk1(c, m.names[i]);			if (err != nil){				if(m.newfid != m.fid){					decref(c.path);					srv.delfid(c);				}				c.path = oldpath;				c.qtype = oldqtype;				if(i == 0)					return err;				srv.reply(ref Rmsg.Walk(m.tag, qids[0:i]));				return nil;			}			qids[i] = Sys->Qid(c.path, 0, c.qtype);		}		decref(oldpath);		srv.reply(ref Rmsg.Walk(m.tag, qids));	Clunk =>		c := srv.clunk(m);		if (c != nil && c.path != Qroot)			decref(c.path);	* =>		srv.default(gm);	}	return nil;} addentry(name: string): ref Sys->Dir{	for (i := 0; i < len refcounts; i++)		if (refcounts[i].refcount == 0)			break;	if (i == len refcounts) {		refcounts = (array[len refcounts * 2] of Entry)[0:] = refcounts;		for (j := i; j < len refcounts; j++)			refcounts[j].refcount = 0;	}	d := dir(name, Sys->DMDIR|8r555, big i | (big uniq++ << 32));	tree.create(Qroot, d);	refcounts[i] = (1, d.qid.path);	return ref d;} incref(q: big){	id := int q;	if (id >= 0 && id < len refcounts){		refcounts[id].refcount++;	}} decref(q: big){	id := int q;	if (id >= 0 && id < len refcounts){		if (--refcounts[id].refcount == 0)			tree.remove(refcounts[id].path);	}} Blankdir: Sys->Dir;dir(name: string, perm: int, qid: big): Sys->Dir{	d := Blankdir;	d.name = name;	d.uid = "me";	d.gid = "me";	d.qid.path = qid;	if (perm & Sys->DMDIR)		d.qid.qtype = Sys->QTDIR;	else		d.qid.qtype = Sys->QTFILE;	d.mode = perm;	return d;}