##       Software from the book "Inferno Programming with Limbo"#       published by John Wiley & Sons, January 2003.##       p. Stanley-Marbell <pip@gemusehaken.org>#implement StyxServer; include "sys.m";include "draw.m";include "arg.m";include "styx.m";include	"styxlib.m"; sys		: Sys;arg		: Arg;styx		: Styx;styxlib		: Styxlib; Styxserver, Rmsg, Tmsg, Dirtab, Chan: import styxlib; mntflg		:= Sys->MREPL;mntpt		:= "/n/remote/";numoranges	: int;Qmax		: con 1024;QSHIFT		: con 4;Qroot, Qorange, Qnew, Qctl, Qdate, Qtime, Qline : con iota;perms		:= array [Qmax] of {Qnew to Qtime => 8r400, * => 8r755};mtimes		:= array [Qmax] of int;atimes		:= array [Qmax] of int;lengths 	:= array [Qmax] of int; StyxServer : module{	init : fn(nil : ref Draw->Context, args : list of string); 	dirgen: fn(srv: ref Styxlib->Styxserver, c: ref Styxlib->Chan,		tab: array of Styxlib->Dirtab, i: int): (int, Sys->Dir);}; init(nil : ref Draw->Context, args : list of string){	sys = load Sys Sys->PATH;	styxlib = load Styxlib Styxlib->PATH;	styx = load Styx Styx->PATH;	arg = load Arg Arg->PATH;	arg->init(args); 	while((c := arg->opt()) != 0)	{		case c		{			'b' => mntflg = Sys->MBEFORE;			'a' => mntflg = Sys->MAFTER;			'r' => mntflg = Sys->MREPL;			'c' => mntflg |= Sys->MCREATE;             		*   =>			{				sys->print("Usage : styxserver [-rabc] <mount point>\n");				exit;			}		}	}	args = arg->argv(); 	if (len args != 1)	{		sys->print("Usage : styxserver [-rabc] <mount point>\n");		exit;	}	mntpt = hd args; 	styxpipe := array [2] of ref Sys->FD;	sys->pipe(styxpipe);	(tmsgchan, srv) := Styxserver.new(styxpipe[0]); 	sync := chan of int;	spawn server(tmsgchan, srv, sync);	<-sync; 	if (sys->mount(styxpipe[1], mntpt, mntflg, nil) < 0)	{		sys->raise(sys->sprint("fail:StyxServer mount failed : %r"));	}} server(tmsgchan : chan of ref Styxlib->Tmsg, srv : ref Styxserver,	sync : chan of int){	devgen := load Dirgenmod "$self"; 	sync <-= 0;	while ()	{		msg := <-tmsgchan;		if (msg == nil)		{			exit;		} 		pick m := msg		{			Readerror =>			{				sys->raise(sys->sprint(					"fail:Styxserver error reading Styx pipe : %r"));			} 			Nop	=>	srv.reply(ref Rmsg.Nop(m.tag));			Attach	=>	srv.devattach(m);			Clone	=>	srv.devclone(m);			Clunk	=>	srv.devclunk(m);			Create	=>	srv.reply(ref Rmsg.Error(m.tag,Styxlib->Eperm));			Flush	=>	srv.devflush(m);			Open	=>	srv.devopen(m, devgen, nil); 			Read	=>			{				c := srv.fidtochan(m.fid); 				if (c == nil)				{					srv.reply(ref Rmsg.Error(m.tag,Styxlib->Eperm));					break;				} 				if (c.isdir())				{					srv.devdirread(m, devgen, nil);					break;				} 				if (c.qid.path == Qnew)				{					if (((numoranges << QSHIFT) + Qline) < Qmax)					{						numoranges++;					} 					srv.reply(ref Rmsg.Read(m.tag, m.fid, nil)); 					break;				} 				srv.reply(ref Rmsg.Error(m.tag,Styxlib->Eperm));			} 			Remove	=>	srv.reply(ref Rmsg.Error(m.tag,Styxlib->Eperm));			Stat	=>	srv.devstat(m, devgen, nil);			Walk	=>	srv.devwalk(m, devgen, nil);			Write	=>	srv.reply(ref Rmsg.Error(m.tag,Styxlib->Eperm));			Wstat	=>	srv.reply(ref Rmsg.Error(m.tag,Styxlib->Eperm));		}	}} dirgen(nil : ref Styxserver, c : ref Chan, nil : array of Dirtab,	entry : int) : (int, Sys->Dir){	level := c.qid.path & ((1 << QSHIFT) - 1); 	#	Top level directory, say /n	if (level == Qroot)	{		if (entry == 0)		{			return (1, packdir("orange", Qorange, Sys->CHDIR, 0));		}	} 	#	Second level directory, say, /n/orange	if (level == Qorange)	{		if (entry == 0)		{			return (1, packdir("new", Qnew, 0, 0));		}		else if (entry <= numoranges)		{			which := entry - 1;			return (1, packdir(sys->sprint("%d", which),					Qline|(which<<QSHIFT), Sys->CHDIR, 0));		}	} 	#	Third level directory, say, /n/orange/5	if (level == Qline)	{		line := (c.qid.path&~Sys->CHDIR) >> QSHIFT; 		case(entry)		{			0 =>	return (1, packdir("ctl", Qctl, 0, line));			1 =>	return (1, packdir("date", Qdate, 0, line));			2 =>	return (1, packdir("time", Qtime, 0, line));		}	} 	return (-1, packdir(nil, 0, 0, 0));} packdir(name : string, Q, dirflag, line : int) : Sys->Dir{	qid : Sys->Qid; 	qid.vers = 0;	qid.path = Q;	qid.path |= line << QSHIFT;	qid.path |= dirflag; 	return Sys->Dir (name,			"pip",			"pip",			qid,			perms[Q] | (qid.path & Sys->CHDIR),			atimes[Q],			mtimes[Q],			lengths[Q],			'O',			'O');}