implement Pop3; include "sys.m";	sys : Sys;include "draw.m";include "bufio.m";	bufio : Bufio;include "pop3.m"; FD, Connection: import sys;Iobuf : import bufio; ibuf, obuf : ref Bufio->Iobuf;conn : int = 0;inited : int = 0; rpid : int = -1;cread : chan of (int, string); DEBUG : con 0; open(user, password, server : string): (int, string){	s : string; 	if (!inited) {		sys = load Sys Sys->PATH;		bufio = load Bufio Bufio->PATH;		inited = 1;	}	if (conn)		return (-1, "connection is already open");	if (server == nil)		server = "$pop3";	(ok, c) := sys->dial ("net!" + server + "!110", nil);	if (ok < 0)		return (-1, "dialup failed");	ibuf = bufio->fopen(c.dfd, Bufio->OREAD);	obuf = bufio->fopen(c.dfd, Bufio->OWRITE);	if (ibuf == nil || obuf == nil)		return (-1, "failed to open bufio");	cread = chan of (int, string);	spawn mreader(cread);	(rpid, nil) = <- cread; 	(ok, s) = mread();	if (ok < 0)		return (-1, s);	(ok, s) = mcmd("USER " + user);	if (ok < 0)		return (-1, s);	(ok, s) = mcmd("PASS " + password);	if (ok < 0)		return (-1, s);	conn = 1;	return (1, nil);} stat() : (int, string, int, int){	if (!conn)		return (-1, "not connected", 0, 0);	(ok, s) := mcmd("STAT");	if (ok < 0)		return (-1, s, 0, 0);	(n, ls) := sys->tokenize(s, " ");	if (n == 3)		return (1, nil, int hd tl ls, int hd tl tl ls);	return (-1, "stat failed", 0, 0);}	msglist() : (int, string, list of (int, int)){	ls : list of (int, int); 	if (!conn)		return (-1, "not connected", nil);	(ok, s) := mcmd("LIST");	if (ok < 0)		return (-1, s, nil);	for (;;) {		(ok, s) = mread();		if (ok < 0)			return (-1, s, nil);		if (len s < 3) {			if (len s > 0 && s[0] == '.')				return (1, nil, rev2(ls));			else				return (-1, s, nil);		}		else {			(n, sl) := sys->tokenize(s, " ");			if (n == 2)				ls = (int hd sl, int hd tl sl) :: ls;			else				return (-1, "bad list format", nil);		}	}} msgnolist() : (int, string, list of int){	ls : list of int; 	if (!conn)		return (-1, "not connected", nil);	(ok, s) := mcmd("LIST");	if (ok < 0)		return (-1, s, nil);	for (;;) {		(ok, s) = mread();		if (ok < 0)			return (-1, s, nil);		if (len s < 3) {			if (len s > 0 && s[0] == '.')				return (1, nil, rev1(ls));			else				return (-1, s, nil);		}		else {			(n, sl) := sys->tokenize(s, " ");			if (n == 2)				ls = int hd sl :: ls;			else				return (-1, "bad list format", nil);		}	}} top(m : int) : (int, string, string){	if (!conn)		return (-1, "not connected", nil);	(ok, s) := mcmd("TOP " + string m + " 1");	if (ok < 0)		return (-1, s, nil);	return getbdy();} get(m : int) : (int, string, string){	if (!conn)		return (-1, "not connected", nil);	(ok, s) := mcmd("RETR " + string m);	if (ok < 0)		return (-1, s, nil);	return getbdy();}	getbdy() : (int, string, string){	b : string; 	for (;;) {		(ok, s) := mread();		if (ok < 0)			return (-1, s, nil);		if (s == ".")			break;		if (len s > 1 && s[0] == '.' && s[1] == '.')			s = s[1:];		b = b + s + "\n";	}	return (1, nil, b);}	delete(m : int) : (int, string){	if (!conn)		return (-1, "not connected");	return mcmd("DELE " + string m);}			close(): (int, string){	if (!conn)		return (-1, "connection not open");	ok := mwrite("QUIT");	kill(rpid);	ibuf.close();	obuf.close();	conn = 0;	if (ok < 0)		return (-1, "failed to close connection");	return (1, nil);} SLPTIME : con 100;MAXSLPTIME : con 10000; mread() : (int, string){	t := 0;	while (t < MAXSLPTIME) {		alt {			(ok, s) := <- cread =>				return (ok, s);			* =>				t += SLPTIME;				sys->sleep(SLPTIME);		}	}	kill(rpid);	return (-1, "smtp timed out\n");	} mreader(c : chan of (int, string)){	c <- = (sys->pctl(0, nil), nil);	for (;;) {		line := ibuf.gets('\n');		if (DEBUG)			sys->print("mread : %s", line);		if (line == nil) {			c <- = (-1, "could not read response from server");			continue;		}		l := len line;		if (line[l-1] == '\n')			l--;		if (line[l-1] == '\r')			l--;		c <- = (1, line[0:l]);	}} mwrite(s : string): int{	s += "\r\n";	if (DEBUG)		sys->print("mwrite : %s", s);	b := array of byte s;	l := len b;	nb := obuf.write(b, l);	obuf.flush();	if (nb != l)		return -1;	return 1;} mcmd(s : string) : (int, string){	ok : int;	r : string; 	ok = mwrite(s);	if (ok < 0)		return (-1, err(s) + " send failed");	(ok, r) = mread();	if (ok < 0)		return (-1, err(s) + " receive failed (" + r + ")");	if (len r > 1 && r[0] == '+')		return (1, r);	return (-1, r);} rev1(l1 : list of int) : list of int{	l2 : list of int; 	for ( ; l1 != nil; l1 = tl l1)		l2 = hd l1 :: l2;	return l2;} rev2(l1 : list of (int, int)) : list of (int, int){	l2 : list of (int, int); 	for ( ; l1 != nil; l1 = tl l1)		l2 = hd l1 :: l2;	return l2;} err(s : string) : string{	for (i := 0; i < len s; i++)		if (s[i] == ' ' || s[i] == ':')			return s[0:i];	return s;} kill(pid : int) : int{	if (pid < 0)		return 0;	fd := sys->open("#p/" + string pid + "/ctl", sys->OWRITE);	if (fd == nil || sys->fprint(fd, "kill") < 0)		return -1;	return 0;}