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kernel: revert /srv/clone

--- a/sys/man/3/srv

+++ b/sys/man/3/srv

@@ -5,8 +5,6 @@

 .nf

 .B bind #s /srv

-.BI #s/ clone

-.BI #s/ n

 .BI #s/ service1

 .BI #s/ service2

  ...

@@ -14,7 +12,7 @@

 .SH DESCRIPTION

 The

 .I srv

-device provides a tree of directories holding

+device provides a one-level directory holding

 already-open channels to services.

 In effect,

 .I srv

@@ -42,18 +40,6 @@

 .PP

 It is an error to write more than one number into a server file,

 or to create a file with a name that is already being used.

-.PP

-Opening the

-.I clone

-file allocates a new service directory. Reading

-.I clone

-returns the id of the new directory. This new service

-directory can then be accessed at

-.BR /srv/id .

-Directories are recursable; each new service directory

-contains its own

-.I clone

-file.

 .SH EXAMPLE

 To drop one end of a pipe into

 .BR /srv ,

--- a/sys/src/9/port/devsrv.c

+++ b/sys/src/9/port/devsrv.c

@@ -5,213 +5,61 @@

 #include	"fns.h"

 #include	"../port/error.h"

-#include	"netif.h"

-typedef struct Link Link;

-struct Link

-{

-	void 	*link;

-	char 	*name;

-	ulong 	path;

-};

-

 typedef struct Srv Srv;

 struct Srv

 {

-	Link;

-

+	char	*name;

 	char	*owner;

 	ulong	perm;

 	Chan	*chan;

+	Srv	*link;

+	ulong	path;

 };

-typedef struct Board Board;

-struct Board

-{

-	Link;

-	RWlock;

-	Ref;

+static QLock	srvlk;

+static Srv	*srv;

+static int	qidpath;

-	Board 	*parent;

-	Board 	*child;

-	Srv 	*srv;

-	long	id;

-	int	qidpath;

-	int 	closed;	

-};

-

-struct{

-	QLock;

-	long path;

-} boards;

-

-enum{

-	Qroot,

-	Qclone,

-	Qlease,

-

-	Qend,

-};

-

-Board root;

-

-static char Eexpired[] = "expired lease";

-

-static void*

-lookup(Link *l, char *name, ulong qidpath)

+static Srv*

+srvlookup(char *name, ulong qidpath)

 {

-	Link *lp;

+	Srv *sp;

-	if(qidpath != ~0UL)

-		qidpath = NETTYPE(qidpath);

-	for(lp = l; lp != nil; lp = lp->link){

-		if(qidpath != ~0UL && lp->path == qidpath)

-			return lp;

-		if(name != nil && strcmp(lp->name, name) == 0)

-			return lp;

+	for(sp = srv; sp != nil; sp = sp->link) {

+		if(sp->path == qidpath || (name != nil && strcmp(sp->name, name) == 0))

+			return sp;

 	}

 	return nil;

 }

-static void*

-remove(Link **l, char *name, ulong qidpath)

-{

-	Link *lp;

-	Link **last;

-

-	if(qidpath != ~0UL)

-		qidpath = NETTYPE(qidpath);

-	last = l;

-	for(lp = *l; lp != nil; lp = lp->link){

-		if(qidpath != ~0UL && lp->path == qidpath)

-			break;

-		if(name != nil && strcmp(lp->name, name) == 0)

-			break;

-		last = &lp->link;

-	}

-	if(lp == nil)

-		return nil;

-

-	*last = lp->link;

-	lp->link = nil;

-	return lp;

-}

-

-static void

-boardclunk(Board *b, int close)

-{

-	Srv *sp, *prv;

-	Board *ch;

-	long ref;

-

-	/* caller holds a wlock */

-	if(b == &root){

-		wunlock(b);

-		return;

-	}

-

-	if(close){

-		assert(b->closed == 0);

-		b->closed++;

-		for(sp = b->srv; sp != nil; sp = prv){

-			prv = sp->link;

-			free(sp->owner);

-			free(sp->name);

-			if(sp->chan != nil)

-				cclose(sp->chan);

-			free(sp);

-		}

-		b->srv = nil;

-	}

-	ref = decref(b);

-

-	/*

-	 * All boards must be walkable from root. So a board

-	 * is allowed to sit at zero references as long as it

-	 * still has active children. For leaf nodes we then

-	 * have to walk up the tree to clear now empty parents.

-	 */

-	while(b->closed && b->child == nil && ref == 0){

-		//Root should never be closed

-		assert(b->parent != nil);

-		wlock(b->parent);

-		ch = remove((Link**)&b->parent->child, b->name, b->path);

-		assert(ch == b);

-

-		b = ch->parent;

-		free(ch->name);

-		wunlock(ch);

-		free(ch);

-	}

-	wunlock(b);

-}

-

 static int

 srvgen(Chan *c, char *name, Dirtab*, int, int s, Dir *dp)

 {

 	Srv *sp;

-	Board *b, *ch;

 	Qid q;

-	if(name != nil && strlen(name) >= sizeof(up->genbuf))

-		return -1;

-

-	b = c->aux;

-	ch = nil;

-	mkqid(&q, ~0L, 0, QTFILE);

-	rlock(b);

-	if(waserror()){

-		runlock(b);

-		return -1;

-	}

 	if(s == DEVDOTDOT){

-		ch = b->parent;

-		if(ch == nil)

-			ch = &root;

-		goto Child;

-		

+		devdir(c, c->qid, "#s", 0, eve, 0555, dp);

+		return 1;

 	}

-	if(name != nil){

-		if(strcmp("clone", name) == 0)

-			goto Clone;

-		sp = lookup(b->srv, name, ~0UL);

-		if(sp == nil)

-			ch = lookup(b->child, name, ~0UL);

-	} else {

-		if(s == 0)

-			goto Clone;

-		s--;

-		for(sp = b->srv; sp != nil && s > 0; sp = sp->link)

+	qlock(&srvlk);

+	if(name != nil)

+		sp = srvlookup(name, -1);

+	else {

+		for(sp = srv; sp != nil && s > 0; sp = sp->link)

 			s--;

-		for(ch = b->child; ch != nil && s > 0; ch = ch->link)

-			s--;

 	}

-	if(sp != nil){

-		kstrcpy(up->genbuf, sp->name, sizeof up->genbuf);

-		q.vers = NETID(c->qid.path);

-		q.path = NETQID(q.vers, sp->path);

-		devdir(c, q, up->genbuf, 0, sp->owner, sp->perm, dp);

-	} else if(ch != nil){

-Child:

-		kstrcpy(up->genbuf, ch->name, sizeof up->genbuf);

-		q.vers = ch->id;

-		q.path = NETQID(q.vers, ch->path);

-		q.type = QTDIR;

-		devdir(c, q, up->genbuf, 0, eve, 0555|DMDIR, dp);

-		/* dirread's and stats shouldn't alter c->aux */

-		if(name != nil)

-			c->aux = ch;

-	} else if(0){

-Clone:

-		q.vers = NETID(c->qid.path);

-		q.path = NETQID(q.vers, Qclone);

-		devdir(c, q, "clone", 0, eve, 0444, dp);

-	} else

-		error(Enonexist);

-

-	runlock(b);

-	poperror();

+	if(sp == nil || (name != nil && (strlen(sp->name) >= sizeof(up->genbuf)))) {

+		qunlock(&srvlk);

+		return -1;

+	}

+	mkqid(&q, sp->path, 0, QTFILE);

+	/* make sure name string continues to exist after we release lock */

+	kstrcpy(up->genbuf, sp->name, sizeof up->genbuf);

+	devdir(c, q, up->genbuf, 0, sp->owner, sp->perm, dp);

+	qunlock(&srvlk);

 	return 1;

 }

@@ -218,36 +66,19 @@

 static void

 srvinit(void)

 {

-	root.qidpath = Qend;

-	root.name = "#s";

+	qidpath = 1;

 }

 static Chan*

 srvattach(char *spec)

 {

-	Chan *c;

-

-	c = devattach('s', spec);

-	c->aux = &root;

-	return c;

+	return devattach('s', spec);

 }

 static Walkqid*

 srvwalk(Chan *c, Chan *nc, char **name, int nname)

 {

-	Board *b;

-	Walkqid *wq;

-

-	wq = devwalk(c, nc, name, nname, 0, 0, srvgen);

-	if(wq == nil || wq->clone == nil)

-		return wq;

-

-	b = wq->clone->aux;

-	if(b == &root)

-		return wq;

-

-	incref(b);

-	return wq;

+	return devwalk(c, nc, name, nname, 0, 0, srvgen);

 }

 static int

@@ -259,14 +90,12 @@

 char*

 srvname(Chan *c)

 {

-	Board *b;

 	Srv *sp;

 	char *s;

 	s = nil;

-	b = &root;

-	rlock(b);

-	for(sp = b->srv; sp != nil; sp = sp->link) {

+	qlock(&srvlk);

+	for(sp = srv; sp != nil; sp = sp->link) {

 		if(sp->chan == c){

 			s = malloc(3+strlen(sp->name)+1);

 			if(s != nil)

@@ -274,7 +103,7 @@

 			break;

 		}

 	}

-	runlock(b);

+	qunlock(&srvlk);

 	return s;

 }

@@ -281,10 +110,8 @@

 static Chan*

 srvopen(Chan *c, int omode)

 {

-	Board *b, *ch;

 	Srv *sp;

 	Chan *nc;

-	char buf[64];

 	if(c->qid.type == QTDIR){

 		if(omode & ORCLOSE)

@@ -296,53 +123,20 @@

 		c->offset = 0;

 		return c;

 	}

-	if(omode&OTRUNC)

-		error(Eexist);

-	if(omode&ORCLOSE)

-		error(Eperm);

-

-	b = c->aux;

-	if(NETTYPE(c->qid.path) == Qclone){;

-		wlock(b);

-		if(b->closed){

-			wunlock(b);

-			error(Eexpired);

-		}

-		ch = smalloc(sizeof *ch);

-		ch->qidpath = Qend;

-		ch->ref = 1;

-		do {

-			qlock(&boards);

-			ch->id = ++boards.path;

-			qunlock(&boards);

-			snprint(buf, sizeof buf, "%ld", ch->id);

-		} while(lookup(b->srv, buf, ~0UL) != nil);

-

-		ch->parent = b;

-		ch->path = b->qidpath++;

-		kstrdup(&ch->name, buf);

-

-		ch->link = b->child;

-		b->child = ch;

-		c->aux = ch;

-		c->qid.vers = ch->id;

-		c->qid.path = NETQID(ch->id, Qlease);

-		boardclunk(b, 0); //unlock

-		return c;

-	}

-

-	rlock(b);

+	qlock(&srvlk);

 	if(waserror()){

-		runlock(b);

+		qunlock(&srvlk);

 		nexterror();

 	}

-	if(b->closed)

-		error(Eexpired);

-	sp = lookup(b->srv, nil, c->qid.path);

+	sp = srvlookup(nil, c->qid.path);

 	if(sp == nil || sp->chan == nil)

 		error(Eshutdown);

+	if(omode&OTRUNC)

+		error(Eexist);

+	if(omode&ORCLOSE)

+		error(Eperm);

 	if(openmode(omode)!=sp->chan->mode && sp->chan->mode!=ORDWR)

 		error(Eperm);

 	devpermcheck(sp->owner, sp->perm, omode);

@@ -350,7 +144,7 @@

 	nc = sp->chan;

 	incref(nc);

-	runlock(b);

+	qunlock(&srvlk);

 	poperror();

 	cclose(c);

@@ -360,7 +154,6 @@

 static Chan*

 srvcreate(Chan *c, char *name, int omode, ulong perm)

 {

-	Board *b;

 	Srv *sp;

 	if(openmode(omode) != OWRITE)

@@ -373,33 +166,27 @@

 	kstrdup(&sp->name, name);

 	kstrdup(&sp->owner, up->user);

-	b = c->aux;

-	wlock(b);

+	qlock(&srvlk);

 	if(waserror()){

-		wunlock(b);

+		qunlock(&srvlk);

 		free(sp->owner);

 		free(sp->name);

 		free(sp);

 		nexterror();

 	}

-	if(b->closed)

-		error(Eexpired);

-	if(lookup(b->srv, name, ~0UL) != nil)

+	if(srvlookup(name, -1) != nil)

 		error(Eexist);

-	if(lookup(b->child, name, ~0UL) != nil)

-		error(Eexist);

 	sp->perm = perm&0777;

-	sp->path = b->qidpath++;

+	sp->path = qidpath++;

-	c->qid.path = NETQID(b->id, sp->path);

-	c->qid.vers = b->id;

+	c->qid.path = sp->path;

 	c->qid.type = QTFILE;

-	sp->link = b->srv;

-	b->srv = sp;

+	sp->link = srv;

+	srv = sp;

-	wunlock(b);

+	qunlock(&srvlk);

 	poperror();

 	c->flag |= COPEN;

@@ -411,24 +198,22 @@

 static void

 srvremove(Chan *c)

 {

-	Board *b;

-	Srv *sp;

+	Srv *sp, **l;

 	if(c->qid.type == QTDIR)

 		error(Eperm);

-	switch(NETTYPE(c->qid.path)){

-	case Qlease:

-	case Qclone:

-		error(Eperm);

-	}

-	b = c->aux;

-	wlock(b);

+	qlock(&srvlk);

 	if(waserror()){

-		wunlock(b);

+		qunlock(&srvlk);

 		nexterror();

 	}

-	sp = lookup(b->srv, nil, c->qid.path);

+	l = &srv;

+	for(sp = *l; sp != nil; sp = *l) {

+		if(sp->path == c->qid.path)

+			break;

+		l = &sp->link;

+	}

 	if(sp == nil)

 		error(Enonexist);

@@ -444,9 +229,10 @@

 	if((sp->perm&7) != 7 && strcmp(sp->owner, up->user) && !iseve())

 		error(Eperm);

-	remove((Link**)&b->srv, nil, c->qid.path);

+	*l = sp->link;

+	sp->link = nil;

-	boardclunk(b, 0); //unlock

+	qunlock(&srvlk);

 	poperror();

 	if(sp->chan != nil)

@@ -459,7 +245,6 @@

 static int

 srvwstat(Chan *c, uchar *dp, int n)

 {

-	Board *b;

 	char *strs;

 	Srv *sp;

 	Dir d;

@@ -466,11 +251,6 @@

 	if(c->qid.type & QTDIR)

 		error(Eperm);

-	switch(NETTYPE(c->qid.path)){

-	case Qlease:

-	case Qclone:

-		error(Eperm);

-	}

 	strs = smalloc(n);

 	if(waserror()){

@@ -481,16 +261,13 @@

 	if(n == 0)

 		error(Eshortstat);

-	b = c->aux;

-	wlock(b);

+	qlock(&srvlk);

 	if(waserror()){

-		wunlock(b);

+		qunlock(&srvlk);

 		nexterror();

 	}

-	if(b->closed)

-		error(Eexpired);

-	sp = lookup(b->srv, nil, c->qid.path);

+	sp = srvlookup(nil, c->qid.path);

 	if(sp == nil)

 		error(Enonexist);

@@ -502,10 +279,6 @@

 			error(Ebadchar);

 		if(strlen(d.name) >= sizeof(up->genbuf))

 			error(Etoolong);

-		if(lookup(b->srv, d.name, ~0UL) != nil)

-			error(Eexist);

-		if(lookup(b->child, d.name, ~0UL) != nil)

-			error(Eexist);

 		kstrdup(&sp->name, d.name);

 	}

 	if(d.uid != nil && *d.uid)

@@ -513,7 +286,7 @@

 	if(d.mode != ~0UL)

 		sp->perm = d.mode & 0777;

-	wunlock(b);

+	qunlock(&srvlk);

 	poperror();

 	free(strs);

@@ -525,47 +298,22 @@

 static void

 srvclose(Chan *c)

 {

-	Board *b;

-	int expired;

-

-	expired = 0;

-	if(NETTYPE(c->qid.path) == Qlease)

-		expired++;

-	else if(c->flag & CRCLOSE){

-		/*

-		 * in theory we need to override any changes in removability

-		 * since open, but since all that's checked is the owner,

-	 	 * which is immutable, all is well.

-	 	 */

+	/*

+	 * in theory we need to override any changes in removability

+	 * since open, but since all that's checked is the owner,

+	 * which is immutable, all is well.

+	 */

+	if(c->flag & CRCLOSE){

 		if(waserror())

-			goto Clunk;

+			return;

 		srvremove(c);

 		poperror();

-		return;

 	}

-Clunk:

-	b = c->aux;

-	wlock(b);

-	boardclunk(b, expired); //unlock

 }

 static long

-srvread(Chan *c, void *va, long n, vlong off)

+srvread(Chan *c, void *va, long n, vlong)

 {

-	Board *b;

-

-	if(NETTYPE(c->qid.path) == Qlease){

-		b = c->aux;

-		rlock(b);

-		if(waserror()){

-			runlock(b);

-			nexterror();

-		}

-		n = readstr((ulong)off, va, n, b->name);

-		runlock(b);

-		poperror();

-		return n;

-	}

 	isdir(c);

 	return devdirread(c, va, n, 0, 0, srvgen);

 }

@@ -573,15 +321,11 @@

 static long

 srvwrite(Chan *c, void *va, long n, vlong)

 {

-	Board *b;

 	Srv *sp;

 	Chan *c1;

 	int fd;

 	char buf[32];

-	if(NETTYPE(c->qid.path) == Qlease)

-		error(Eperm);

-

 	if(n >= sizeof buf)

 		error(Etoobig);

 	memmove(buf, va, n);	/* so we can NUL-terminate */

@@ -590,18 +334,15 @@

 	c1 = fdtochan(fd, -1, 0, 1);	/* error check and inc ref */

-	b = c->aux;

-	wlock(b);

+	qlock(&srvlk);

 	if(waserror()) {

-		wunlock(b);

+		qunlock(&srvlk);

 		cclose(c1);

 		nexterror();

 	}

-	if(b->closed)

-		error(Eexpired);

 	if(c1->qid.type & QTAUTH)

 		error("cannot post auth file in srv");

-	sp = lookup(b->srv, nil, c->qid.path);

+	sp = srvlookup(nil, c->qid.path);

 	if(sp == nil)

 		error(Enonexist);

@@ -610,7 +351,7 @@

 	sp->chan = c1;

-	wunlock(b);

+	qunlock(&srvlk);

 	poperror();

 	return n;

 }

@@ -639,14 +380,12 @@

 void

 srvrenameuser(char *old, char *new)

 {

-	Board *b;

 	Srv *sp;

-	b = &root;

-	wlock(b);

-	for(sp = b->srv; sp != nil; sp = sp->link) {

+	qlock(&srvlk);

+	for(sp = srv; sp != nil; sp = sp->link) {

 		if(sp->owner != nil && strcmp(old, sp->owner) == 0)

 			kstrdup(&sp->owner, new);

 	}

-	wunlock(b);

+	qunlock(&srvlk);

 }