#include <u.h>#include <libc.h>#include <fcall.h>#include <thread.h>#include <9p.h>#include "post.h" Postcrud*_post1(Srv *s, char *name, char *mtpt, int flag){	Postcrud *p; 	p = emalloc9p(sizeof *p);	if(!s->nopipe){		if(pipe(p->fd) < 0)			sysfatal("pipe: %r");		s->infd = s->outfd = p->fd[1];		s->srvfd = p->fd[0];	}	if(name)		if(postfd(name, s->srvfd) < 0)			sysfatal("postfd %s: %r", name);	p->s = s;	p->mtpt = mtpt;	p->flag = flag;	return p;} void_post2(void *v){	Srv *s; 	s = v;	if(!s->leavefdsopen){		rfork(RFNOTEG);		rendezvous((ulong)s, 0);		close(s->srvfd);	}	srv(s);} void_post3(Postcrud *p){	/*	 * Normally the server is posting as the last thing it does	 * before exiting, so the correct thing to do is drop into	 * a different fd space and close the 9P server half of the	 * pipe before trying to mount the kernel half.  This way,	 * if the file server dies, we don't have a ref to the 9P server	 * half of the pipe.  Then killing the other procs will drop	 * all the refs on the 9P server half, and the mount will fail.	 * Otherwise the mount hangs forever.	 *	 * Libthread in general and acme win in particular make	 * it hard to make this fd bookkeeping work out properly,	 * so leaveinfdopen is a flag that win sets to opt out of this	 * safety net.	 */	if(!p->s->leavefdsopen){		rfork(RFFDG);		rendezvous((ulong)p->s, 0);		close(p->s->infd);		if(p->s->infd != p->s->outfd)			close(p->s->outfd);	} #if 0	if(p->mtpt){		if(amount(p->s->srvfd, p->mtpt, p->flag, "") == -1)			sysfatal("mount %s: %r", p->mtpt);	}else#endif		close(p->s->srvfd);	free(p);}