/*	csrv - central services distributed registry infrastructure 	Copyright (C) 2010, IBM Corporation,  		Eric Van Hensbergen (bergevan@us.ibm.com) 	Description:		This sets up the per-node mount hierarchy for aggregated		distributed services.  Since name space operations are 		performed in the context of the original application they		are reflected in all subsequent mounts and exports. 	BUGS:		* ctl operations are single threaded, hangs on errors		* mount is particularly brittle		* cleanup usually misses mntgen*/ #include <u.h>#include <libc.h>#include <fcall.h>#include <thread.h>#include <9p.h>#include <mp.h>#include <libsec.h> char Eperm[] =		"permission denied";char Ebadctl[] = "bad ctl command or arguments";char Ebind[] = "bind failed"; ulong	mntgenpid;char 	defaultcsrvpath[] =	"/csrv";char *csrvpath;Channel *ctlchan, *ctlrespchan; static voidusage(void){	fprint(2, "csrv [-D] [mtpt]\n");	threadexits("usage");} enum{	STACK = 2048,}; enum{	Cmount,	Cbind,	Cunmount,	Cexit,}; Cmdtab ctltab[]={	Cmount,	"mount", 3,	Cbind,	"bind", 3,	Cunmount,"unmount", 2,	Cexit,	"exit", 1,};	 voidkillall(Srv*){	send(ctlchan, "exit");	unmount(0, csrvpath);	threadexitsall("killall");} static voidfswrite(Req *r){	char buf[255]; 	if(r->ifcall.count > 254)		respond(r, "ctl buffer overflow"); 	strncpy(buf, r->ifcall.data, r->ifcall.count);	buf[r->ifcall.count] = 0; 	if(send(ctlchan, buf) < 0) {		respond(r, "send ctl chan error");		return;	} 	if(recv(ctlrespchan, buf) < 0) {		respond(r, "recv ctl chan error");		return;	}		if(buf[0] != 0)		respond(r, buf);	else		respond(r, nil);} Srv fs={	.write=			fswrite,	.end=			killall,}; enum{	Xctl	= 1,}; /* start up a mntgen for us to work with */static voidmntgen(void *arg){	char *path = (char *) arg; 	procexecl(0, "/bin/mntgen", "/bin/mntgen", path, 0); 	threadexits("exec");} /* If anything goes wrong here its a pain *//* TODO: move to threads with timeouts or something */static voidmountit(char *dest, char *old){	char dir[1024];	int fd; 	dest = netmkaddr(dest, 0, "9fs");	fd = dial(dest, 0, dir, 0);	if(fd < 0) {		fprint(2, "csrv: dial %s: %r\n", dest);		return;	}	if(mount(fd, -1, old, MREPL, "") < 0)		fprint(2, "csrv: mount on %s: %r\n", old);} static voidctlworker(void *){	char ctlbuf[255];	char newpath[255];	Cmdbuf *cb;	Cmdtab *cmd; 	while(1) {		memset(ctlbuf, 255, 0);		if(recv(ctlchan, ctlbuf) < 0)			threadexits("ctlworker rcvchan error");		cb = parsecmd(ctlbuf, strlen(ctlbuf));		cmd = lookupcmd(cb, ctltab, nelem(ctltab));		if(cmd == nil) {			send(ctlrespchan, Ebadctl);			free(cb);			continue;		} 		send(ctlrespchan, "\0"); /* success */ 		switch(cmd->index){		case Cmount:			snprint(newpath, 255, "%s/%s", csrvpath, cb->f[2]);			mountit(cb->f[1], newpath);				break;		case Cbind:			snprint(newpath, 255, "%s/%s", csrvpath, cb->f[2]);			if(bind(cb->f[1], newpath, MREPL) < 0)				fprint(2, "csrv: bind %s %s: %r\n", cb->f[1], newpath);			break;		case Cunmount:			snprint(newpath, 255, "%s/%s", csrvpath, cb->f[1]);			unmount(0, newpath);			break;		case Cexit:			free(cb);			unmount(0, csrvpath);			threadexitsall("exitrequested");		}		free(cb);	} } voidthreadmain(int argc, char **argv){	ARGBEGIN{	case 'D':		chatty9p++;		break;	default:		usage();	}ARGEND 	if(argc > 1)		usage(); 	if(argc)		csrvpath = argv[0];	else		csrvpath = defaultcsrvpath;  	fs.tree = alloctree("csrv", "csrv", DMDIR|0555, nil);	closefile(createfile(fs.tree->root, "ctl", "csrv", 0222, (void *)Xctl)); 	ctlchan = chancreate(255, 0);	/* ctl command channel */	ctlrespchan = chancreate(255, 0); /* response channel */ 	proccreate(mntgen, csrvpath, STACK); 	threadpostmountsrv(&fs, nil, csrvpath, MBEFORE); 	proccreate(ctlworker, nil, STACK); 	threadexits(0);}