implement Proxy; include "sys.m";	sys: Sys; include "srvmgr.m";include "proxy.m"; Srvreq, Srvreply: import Srvmgr; init(root: string, fd: ref Sys->FD, rc: chan of ref Srvreq, user: string){	sys = load Sys Sys->PATH; 	sys->chdir(root);	sys->bind("export/services", "export/services", Sys->MCREATE);	sys->bind("#s", "export/services", Sys->MBEFORE); 	ctlio := sys->file2chan("export/services", "ctl"); 	hangup := chan of int;	spawn export(fd, "export", hangup);	fd = nil; 	for (;;) alt {	<- hangup =>		# closedown all clients		sys->print("client exit [%s]\n", user);		rmclients(rc);		return;	(offset, count, fid, r) := <- ctlio.read =>		client := fid2client(fid);		if (r == nil) {			if (client != nil)				rmclient(rc, client);			continue;		}		if (client == nil) {			rreply(r, (nil, "service not set"));			continue;		}		rreply(r, reads(client.path, offset, count)); 	(offset, data, fid, w) := <- ctlio.write =>		client := fid2client(fid);		if (w == nil) {			if (client != nil)				rmclient(rc, client);			continue;		}		if (client != nil) {			wreply(w, (0, "service set"));			continue;		}		err := newclient(rc, user, fid, string data);		if (err != nil)			wreply(w, (0, err));		else			wreply(w, (len data, nil));	}	} rreply(rc: chan of (array of byte, string), reply: (array of byte, string)){	alt {	rc <-= reply =>;	* =>;	}} wreply(wc: chan of (int, string), reply: (int, string)){	alt {	wc <-= reply=>;	* =>;	}} reads(str: string, off, nbytes: int): (array of byte, string){	bstr := array of byte str;	slen := len bstr;	if(off < 0 || off >= slen)		return (nil, nil);	if(off + nbytes > slen)		nbytes = slen - off;	if(nbytes <= 0)		return (nil, nil);	return (bstr[off:off+nbytes], nil);} export(exportfd: ref Sys->FD, dir: string, done: chan of int){	sys->export(exportfd, dir, Sys->EXPWAIT);	done <-= 1;} Client: adt {	fid: int;	path: string;	sname: string;	id: string;}; clients: list of ref Client;freepaths: list of string;nextpath := 0; fid2client(fid: int): ref Client{	for(cl := clients; cl != nil; cl = tl cl)		if ((c := hd cl).fid == fid)			return c;	return nil;} newclient(rc: chan of ref Srvreq, user: string, fid: int, cmd: string): string{sys->print("new Client %s [%s]\n", user, cmd);	for (i := 0; i < len cmd; i++)		if (cmd[i] == ' ')			break;	if (i == 0 || i == len cmd)		return "bad command"; 	sname := cmd[:i];	id := cmd[i:];	reply := chan of Srvreply;	rc <-= ref Srvreq.Acquire(sname, id, user, reply);	(err, root, fd) := <- reply;	if (err != nil)		return err; 	path := "";	if (freepaths != nil)		(path, freepaths) = (hd freepaths, tl freepaths);	else		path = string nextpath++; 	sys->mount(fd, nil, "mnt", Sys->MREPL, nil);	# connection to the active service fs	mkdir("export/services/"+path);	sys->bind("mnt/"+root, "export/services/"+path, Sys->MREPL|Sys->MCREATE);	sys->unmount("mnt", nil);	clients = ref Client(fid, path, sname, id) :: clients;	return nil;} rmclient(rc: chan of ref Srvreq, client: ref Client){sys->print("rmclient [%s %s]\n", client.sname, client.id);	nl: list of ref Client;	for(cl := clients; cl != nil; cl = tl cl)		if((c := hd cl) == client){			sys->unmount("export/services/" + client.path, nil);			freepaths = client.path :: freepaths;			rc <-= ref Srvreq.Release(client.sname, client.id);		} else			nl = c :: nl;	clients = nl;} rmclients(rc: chan of ref Srvreq){	for(cl := clients; cl != nil; cl = tl cl){		c := hd cl;sys->print("rmclients [%s %s]\n", c.sname, c.id);		rc <-= ref Srvreq.Release(c.sname, c.id);	}	clients = nil;} mkdir(path: string){	sys->print("mkdir [%s]\n", path);	sys->create(path, Sys->OREAD, 8r777 | Sys->DMDIR);}