/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include "cec.h" typedef struct {	char	type;	char	pad[3];	Pkt	p;} Muxmsg; typedef struct {	int	fd;	int	type;	int	pid;} Muxproc; struct Mux {	Muxmsg	m;	Muxproc	p[2];	int	pfd[2];	int	inuse;}; static Mux smux = {.inuse	= -1,}; voidmuxcec(int, int cfd){	Muxmsg m;	int l; 	m.type = Fcec;	while((l = netget(&m.p, sizeof m.p)) > 0)		if(write(cfd, &m, l+4) != l+4)			break;	exits("");} voidmuxkbd(int kfd, int cfd){	Muxmsg m; 	m.type = Fkbd;	while((m.p.len = read(kfd, m.p.data, sizeof m.p.data)) > 0)		if(write(cfd, &m, m.p.len+22) != m.p.len+22)			break;	m.type = Ffatal;	write(cfd, &m, 4);	exits("");} intmuxproc(Mux *m, Muxproc *p, int fd, void (*f)(int, int), int type){	memset(p, 0, sizeof p);	p->type = -1;	switch(p->pid = rfork(RFPROC|RFFDG)){	case -1:		return -1;	case 0:		close(m->pfd[0]);		f(fd, m->pfd[1]);	default:		p->fd = fd;		p->type = type;		return p->pid;	}} voidmuxfree(Mux *m){	close(m->pfd[0]);	close(m->pfd[1]);	postnote(PNPROC, m->p[0].pid, "this note goes to 11");	postnote(PNPROC, m->p[1].pid, "this note goes to 11");	waitpid();	waitpid();	memset(m, 0, sizeof *m);	m->inuse = -1;} Mux*mux(int fd[2]){	Mux *m; 	if(smux.inuse != -1)		sysfatal("mux in use");	m = &smux;	m->inuse = 1;	if(pipe(m->pfd) == -1)		sysfatal("pipe: %r");	muxproc(m, m->p+0, fd[0], muxkbd, Fkbd);	muxproc(m, m->p+1, fd[1], muxcec, Fcec);	close(m->pfd[1]);	return m;} intmuxread(Mux *m, Pkt *p){	if(read(m->pfd[0], &m->m, sizeof m->m) == -1)		return -1;	memcpy(p, &m->m.p, sizeof *p);	return m->m.type;}