#include "u.h"#include "../port/lib.h"#include "mem.h"#include "dat.h"#include "fns.h"#include "../port/error.h" #include "ip.h" enum{	Maxtu=	16*1024,}; typedef struct LB LB;struct LB{	Proc	*readp;	Queue	*q;	Fs	*f;}; static void loopbackread(void *a); static voidloopbackbind(Ipifc *ifc, int, char**){	LB *lb; 	lb = smalloc(sizeof(*lb));	lb->readp = (void*)-1;	lb->f = ifc->conv->p->f;	lb->q = qopen(1024*1024, Qmsg, nil, nil);	ifc->arg = lb; 	kproc("loopbackread", loopbackread, ifc, 0); } static voidloopbackunbind(Ipifc *ifc){	LB *lb = ifc->arg; 	while(waserror())		; 	/* wat for reader to start */	while(lb->readp == (void*)-1)		tsleep(&up->sleep, return0, 0, 300);			if(lb->readp != nil)		postnote(lb->readp, 1, "unbind", 0); 	poperror(); 	wunlock(ifc);	while(waserror())		; 	/* wait for reader to die */	while(lb->readp != nil)		tsleep(&up->sleep, return0, 0, 300); 	poperror();	wlock(ifc); 	/* clean up */	qfree(lb->q);	free(lb);} static voidloopbackbwrite(Ipifc *ifc, Block *bp, int, uchar*){	LB *lb; 	lb = ifc->arg;	if(qpass(lb->q, bp) < 0)		ifc->outerr++;	ifc->out++;} static voidloopbackread(void *a){	Ipifc *ifc;	Block *bp;	LB *lb; 	ifc = a;	lb = ifc->arg;	lb->readp = up;	/* hide identity under a rock for unbind */	if(!waserror())	while((bp = qbread(lb->q, Maxtu)) != nil){		rlock(ifc);		if(waserror()){			runlock(ifc);			nexterror();		}		ifc->in++;		if(ifc->lifc == nil)			freeb(bp);		else			ipiput4(lb->f, ifc, bp);		runlock(ifc);		poperror();	}	lb->readp = nil;	pexit("hangup", 1);} Medium loopbackmedium ={.hsize=		0,.mintu=		0,.maxtu=		Maxtu,.maclen=	0,.name=		"loopback",.bind=		loopbackbind,.unbind=	loopbackunbind,.bwrite=	loopbackbwrite,}; voidloopbackmediumlink(void){	addipmedium(&loopbackmedium);}