nfs.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

		mode &= (attr.mode&0777) | ~0777;
	gid = attr.gid;

	if(r->ifcall.perm&DMDIR)
		mk = nfsMkdir;
	else
		mk = nfsCreate;

	if((*mk)(aux->auth, r->tag, &aux->handle, r->ifcall.name, &h, mode, gid, &have, &attr) < 0
	|| (!have && nfsGetattr(aux->auth, r->tag, &h, &attr) < 0)){
		responderrstr(r);
		return;
	}
	attrToQid(&attr, &r->fid->qid);
	aux->parent = aux->handle;
	aux->handle = h;
	free(aux->name);
	aux->name = estrdup9p(r->ifcall.name);
	r->ofcall.qid = r->fid->qid;
	respond(r, nil);
}

void
fsreaddir(Req *r)
{
	FidAux *aux;
	uchar *p, *freeme, *ep, *p9, *ep9;
	char *s;
	uint count;
	int n, (*unpack)(uchar*, uchar*, uchar**, Nfs3Entry*);
	Nfs3Entry e;
	u64int cookie;
	Dir d;

	aux = r->fid->aux;
	/*
	 * r->ifcall.count seems a reasonable estimate to
	 * how much NFS entry data we want.  is it?
	 */
	if(r->ifcall.offset)
		cookie = aux->cookie;
	else
		cookie = 0;
	if(nfsReadDir(aux->auth, r->tag, &aux->handle, r->ifcall.count, cookie,
		&p, &count, &unpack, &freeme) < 0){
		responderrstr(r);
		return;
	}
	ep = p+count;

	p9 = (uchar*)r->ofcall.data;
	ep9 = p9+r->ifcall.count;

	/*
	 * BUG: Issue all of the stat requests in parallel.
	 */
	while(p < ep && p9 < ep9){
		if((*unpack)(p, ep, &p, &e) < 0)
			break;
		aux->cookie = e.cookie;
		if(strcmp(e.name, ".") == 0 || strcmp(e.name, "..") == 0)
			continue;
		for(s=e.name; (uchar)*s >= ' '; s++)
			;
		if(*s != 0)	/* bad character in name */
			continue;
		if(!e.haveAttr && !e.haveHandle)
			if(nfsLookup(aux->auth, r->tag, &aux->handle, e.name, &e.handle, &e.haveAttr, &e.attr) < 0)
				continue;
		if(!e.haveAttr)
			if(nfsGetattr(aux->auth, r->tag, &e.handle, &e.attr) < 0)
				continue;
		memset(&d, 0, sizeof d);
		attrToDir(&e.attr, &d);
		d.name = e.name;
		if((n = convD2M(&d, p9, ep9-p9)) <= BIT16SZ)
			break;
		p9 += n;
	}
	free(freeme);
	r->ofcall.count = p9 - (uchar*)r->ofcall.data;
	respond(r, nil);
}
	
void
fsread(Req *r)
{
	uchar *p, *freeme;
	uint count;
	FidAux *aux;

	if(r->fid->qid.type&QTDIR){
		fsreaddir(r);
		return;
	}

	aux = r->fid->aux;
	if(nfsRead(aux->auth, r->tag, &aux->handle, r->ifcall.count, r->ifcall.offset, &p, &count, &freeme) < 0){
		responderrstr(r);
		return;
	}
	r->ofcall.data = (char*)p;
	r->ofcall.count = count;
	respond(r, nil);
	free(freeme);
}

void
fswrite(Req *r)
{
	uint count;
	FidAux *aux;

	aux = r->fid->aux;
	if(nfsWrite(aux->auth, r->tag, &aux->handle, (uchar*)r->ifcall.data, r->ifcall.count, r->ifcall.offset, &count) < 0){
		responderrstr(r);
		return;
	}
	r->ofcall.count = count;
	respond(r, nil);
}

void
fsremove(Req *r)
{
	int n;
	FidAux *aux;

	aux = r->fid->aux;
	if(aux->name == nil){
		respond(r, "nfs3client botch -- don't know parent handle in remove");
		return;
	}
	if(r->fid->qid.type&QTDIR)
		n = nfsRmdir(aux->auth, r->tag, &aux->parent, aux->name);
	else
		n = nfsRemove(aux->auth, r->tag, &aux->parent, aux->name);
	if(n < 0){
		responderrstr(r);
		return;
	}
	respond(r, nil);
}

void
fsstat(Req *r)
{
	FidAux *aux;
	Nfs3Attr attr;

	aux = r->fid->aux;
	if(nfsGetattr(aux->auth, r->tag, &aux->handle, &attr) < 0){
		responderrstr(r);
		return;
	}
	memset(&r->d, 0, sizeof r->d);
	attrToDir(&attr, &r->d);
	r->d.name = estrdup9p(aux->name ? aux->name : "???");
	respond(r, nil);
}

void
fswstat(Req *r)
{
	int op, sync;
	FidAux *aux;
	Nfs3SetAttr attr;

	memset(&attr, 0, sizeof attr);
	aux = r->fid->aux;

	/* Fill out stat first to catch errors */
	op = 0;
	sync = 1;
	if(~r->d.mode){
		if(r->d.mode&(DMAPPEND|DMEXCL)){
			respond(r, "wstat -- DMAPPEND and DMEXCL bits not supported");
			return;
		}
		op = 1;
		sync = 0;
		attr.setMode = 1;
		attr.mode = r->d.mode & 0777;
	}
	if(r->d.uid && r->d.uid[0]){
		attr.setUid = 1;
		if(strtouid(r->d.uid, &attr.uid) < 0){
			respond(r, "wstat -- unknown uid");
			return;
		}
		op = 1;
		sync = 0;
	}
	if(r->d.gid && r->d.gid[0]){
		attr.setGid = 1;
		if(strtogid(r->d.gid, &attr.gid) < 0){
			respond(r, "wstat -- unknown gid");
			return;
		}
		op = 1;
		sync = 0;
	}
	if(~r->d.length){
		attr.setSize = 1;
		attr.size = r->d.length;
		op = 1;
		sync = 0;
	}
	if(~r->d.mtime){
		attr.setMtime = Nfs3SetTimeClient;
		attr.mtime.sec = r->d.mtime;
		op = 1;
		sync = 0;
	}
	if(~r->d.atime){
		attr.setAtime = Nfs3SetTimeClient;
		attr.atime.sec = r->d.atime;
		op = 1;
		sync = 0;
	}

	/* Try rename first because it's more likely to fail (?) */
	if(r->d.name && r->d.name[0]){
		if(aux->name == nil){
			respond(r, "nfsclient botch -- don't know parent handle in rename");
			return;
		}
		if(nfsRename(aux->auth, r->tag, &aux->parent, aux->name, &aux->parent, r->d.name) < 0){
			responderrstr(r);
			return;
		}
		free(aux->name);
		aux->name = estrdup9p(r->d.name);
		sync = 0;
	}

	/*
	 * Now we have a problem.  The rename succeeded
	 * but the setattr could fail.  Sic transit atomicity.
	 */
	if(op){
		if(nfsSetattr(aux->auth, r->tag, &aux->handle, &attr) < 0){
			responderrstr(r);
			return;
		}
	}

	if(sync){
		/* NFS commit */
		if(nfsCommit(aux->auth, r->tag, &aux->handle) < 0){
			responderrstr(r);
			return;
		}
	}

	respond(r, nil);
}

char*
fswalk1(Fid *fid, char *name, void *v)
{
	u1int have;
	ulong tag;
	FidAux *aux;
	Nfs3Attr attr;
	Nfs3Handle h;

	tag = *(ulong*)v;
	aux = fid->aux;

	if(nfsLookup(aux->auth, tag, &aux->handle, name, &h, &have, &attr) < 0
	|| (!have && nfsGetattr(aux->auth, tag, &h, &attr) < 0)){
		rerrstr(aux->err, sizeof aux->err);
		return aux->err;
	}

	aux->parent = aux->handle;
	aux->handle = h;
	free(aux->name);
	if(strcmp(name, "..") == 0)
		aux->name = nil;
	else
		aux->name = estrdup9p(name);
	attrToQid(&attr, &fid->qid);
	return nil;
}

char*
fsclone(Fid *fid, Fid *newfid, void*)
{
	FidAux *a, *na;

	a = fid->aux;
	na = emalloc9p(sizeof(FidAux));
	*na = *a;
	if(na->name)
		na->name = estrdup9p(na->name);
	newfid->aux = na;
	if(na->auth)
		na->auth->ref++;
	return nil;
}

void
fswalk(Req *r)
{
	walkandclone(r, fswalk1, fsclone, &r->tag);
}

void
fsflush(Req *r)
{
	Req *or;

	/*
	 * Send on the flush channel(s).
	 * The library will make sure the response
	 * is delayed as necessary.
	 */
	or = r->oldreq;
	if(nfscli)
		sendul(nfscli->flushchan, (ulong)or->tag);
	if(mntcli)
		sendul(mntcli->flushchan, (ulong)or->tag);
	respond(r, nil);
}

void
fsdispatch(void *v)
{
	Req *r;

	r = v;
	switch(r->ifcall.type){
	default:	respond(r, "unknown type");	break;
	case Tattach:	fsattach(r);	break;
	case Topen:	fsopen(r);	break;
	case Tcreate:	fscreate(r);	break;
	case Tread:	fsread(r);	break;
	case Twrite:	fswrite(r);	break;
	case Tremove:	fsremove(r);	break;
	case Tflush:	fsflush(r);	break;
	case Tstat:	fsstat(r);	break;
	case Twstat:	fswstat(r);	break;
	case Twalk:	fswalk(r);	break;
	}
}

void
fsthread(void*)
{
	Req *r;

	while((r = recvp(fschan)) != nil)
		threadcreate(fsdispatch, r, SunStackSize);
}

void
fssend(Req *r)
{
	sendp(fschan, r);
}

void
fsdie(Srv*)
{
	threadexitsall(nil);
}

Srv fs =
{
.destroyfid =	fsdestroyfid,
.attach=		fssend,
.open=		fssend,
.create=		fssend,
.read=		fssend,
.write=		fssend,
.remove=		fssend,
.flush=		fssend,
.stat=		fssend,
.wstat=		fssend,
.walk=		fssend,
.end=		fsdie
};

void
usage(void)
{
	fprint(2, "usage: nfs [-DRv] [-p perm] [-s srvname] [-u passwd group] addr [addr]\n");
	fprint(2, "\taddr - address of portmapper server\n");
	fprint(2, "\taddr addr - addresses of mount server and nfs server\n");
	exits("usage");
}

char*
netchangeport(char *addr, uint port, char *buf, uint nbuf)
{
	char *r;

	strecpy(buf, buf+nbuf, addr);
	r = strrchr(buf, '!');
	if(r == nil)
		return nil;
	r++;
	seprint(r, buf+nbuf, "%ud", port);
	return buf;
}

char mbuf[256], nbuf[256];
char *mountaddr, *nfsaddr;
Channel *csync;
int chattyrpc;
void dialproc(void*);

void
threadmain(int argc, char **argv)
{
	char *srvname, *passwd, *group, *addr, *p;
	SunClient *cli;
	int proto;
	uint mport, nport;
	ulong perm;
	Dir d;

	perm = 0600;
	passwd = nil;
	group = nil;
	srvname = nil;
	sys = sysname();
	if(sys == nil)
		sys = "plan9";
	ARGBEGIN{
	default:
		usage();
	case 'D':
		chatty9p++;
		break;
	case 'R':
		chattyrpc++;
		break;
	case 'p':
		perm = strtol(EARGF(usage()), &p, 8);
		if(perm==0 || *p != 0)
			usage();
		break;
	case 's':
		srvname = EARGF(usage());
		break;
	case 'u':
		passwd = EARGF(usage());
		group = EARGF(usage());
		break;
	case 'v':
		verbose++;
		break;
	}ARGEND

	if(argc != 1 && argc != 2)
		usage();

	if(srvname == nil)
		srvname = argv[0];

	fmtinstall('B', sunRpcFmt);
	fmtinstall('C', sunCallFmt);
	fmtinstall('H', encodefmt);
	sunFmtInstall(&portProg);
	sunFmtInstall(&nfs3Prog);
	sunFmtInstall(&nfsMount3Prog);

	if(passwd && (map = readmap(passwd, group)) == nil)
		fprint(2, "warning: reading %s and %s: %r\n", passwd, group);

	if(map == nil)
		map = &emptymap;

	if(argc == 1){
		addr = netmkaddr(argv[0], "udp", "portmap");
		if((cli = sunDial(addr)) == nil)
			sysfatal("dial %s: %r", addr);
		cli->chatty = chattyrpc;
		sunClientProg(cli, &portProg);
		if(strstr(addr, "udp!"))
			proto = PortProtoUdp;
		else
			proto = PortProtoTcp;
		if(getport(cli, NfsMount3Program, NfsMount3Version, proto, &mport) < 0)
			sysfatal("lookup mount program port: %r");
		if(getport(cli, Nfs3Program, Nfs3Version, proto, &nport) < 0)
			sysfatal("lookup nfs program port: %r");
		sunClientClose(cli);
		mountaddr = netchangeport(addr, mport, mbuf, sizeof mbuf);
		nfsaddr = netchangeport(addr, nport, nbuf, sizeof nbuf);
		strcat(mountaddr, "!r");
		strcat(nfsaddr, "!r");
		if(verbose)
			fprint(2, "nfs %s %s\n", mountaddr, nfsaddr);
	}else{
		mountaddr = argv[0];
		nfsaddr = argv[1];
	}

	/* have to dial in another proc because it creates threads */
	csync = chancreate(sizeof(void*), 0);
	proccreate(dialproc, nil, SunStackSize);
	recvp(csync);

	threadpostmountsrv(&fs, srvname, nil, 0);
	if(perm != 0600){
		p = smprint("/srv/%s", srvname);
		if(p){
			nulldir(&d);
			d.mode = perm;
			dirwstat(p, &d);
		}
	}
	threadexits(nil);
}

void
dialproc(void*)
{
	rfork(RFNAMEG);
	rfork(RFNOTEG);
	if((mntcli = sunDial(mountaddr)) == nil)
		sysfatal("dial mount program at %s: %r", mountaddr);
	mntcli->chatty = chattyrpc;
	sunClientProg(mntcli, &nfsMount3Prog);
	if(mountNull(0) < 0)
		sysfatal("execute nop with mnt server at %s: %r", mountaddr);
	
	if((nfscli = sunDial(nfsaddr)) == nil)
		sysfatal("dial nfs program at %s: %r", nfsaddr);
	nfscli->chatty = chattyrpc;
	sunClientProg(nfscli, &nfs3Prog);
	if(nfsNull(0) < 0)
		sysfatal("execute nop with nfs server at %s: %r", nfsaddr);

	fschan = chancreate(sizeof(Req*), 0);
	threadcreate(fsthread, nil, SunStackSize);
	sendp(csync, 0);
}