code: plan9front

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kernel: private srv boards

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

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

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

 .nf

 .B bind #s /srv

+.BI #s/ clone

+.BI #s/ n

 .BI #s/ service1

 .BI #s/ service2

  ...

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

 .SH DESCRIPTION

 The

 .I srv

-device provides a one-level directory holding

+device provides a tree of directories holding

 already-open channels to services.

 In effect,

 .I srv

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

 .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

@@ -5,61 +5,209 @@

 #include	"fns.h"

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

+#define SRVTYPE(x)	(((uvlong)x)&0x3)

+#define SRVPATH(x)	(((uvlong)x)>>2)

+#define SRVQID(x, t)	((((uvlong)x)<<2)|((t)&0x3))

-typedef struct Srv Srv;

-struct Srv

+typedef struct Link Link;

+struct Link

 {

-	char	*name;

+	void 	*link;

+	char 	*name;

+	ulong 	path;

 	char	*owner;

 	ulong	perm;

+};

+

+typedef struct Srv Srv;

+struct Srv

+{

+	Link;

 	Chan	*chan;

-	Srv	*link;

-	ulong	path;

 };

-static QLock	srvlk;

-static Srv	*srv;

-static int	qidpath;

+typedef struct Board Board;

+struct Board

+{

+	Link;

+	Ref;

-static Srv*

-srvlookup(char *name, ulong qidpath)

+	Board 	*parent;

+	Board 	*child;

+	Srv 	*srv;

+	int 	closed;	

+};

+

+enum{

+	Qsrv,

+	Qclone,

+	Qlease,

+};

+

+Board root;

+RWlock srvlk;

+ulong srvpath;

+

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

+

+static void*

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

 {

-	Srv *sp;

+	Link *lp;

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

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

-			return sp;

+	if(qidpath != ~0UL){

+		assert(SRVTYPE(qidpath) == Qsrv);

+		qidpath = SRVPATH(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;

+	}

 	return nil;

 }

+static void*

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

+{

+	Link *lp;

+	Link **last;

+

+	if(qidpath != ~0UL){

+		assert(SRVTYPE(qidpath) == Qsrv);

+		qidpath = SRVPATH(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;

+

+	if(b == &root)

+		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);

+		ch = remove((Link**)&b->parent->child, b->name, ~0UL);

+		assert(ch == b);

+

+		b = ch->parent;

+		free(ch->name);

+		free(ch->owner);

+		free(ch);

+	}

+}

+

 static int

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

 {

 	Srv *sp;

+	Board *b, *ch;

 	Qid q;

-	if(s == DEVDOTDOT){

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

-		return 1;

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

+		return -1;

+

+	b = c->aux;

+	ch = nil;

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

+	rlock(&srvlk);

+	if(waserror()){

+		runlock(&srvlk);

+		nexterror();

 	}

+	switch(s){

+	case -2: /* dot */

+		ch = b;

+		goto Child;

+	case DEVDOTDOT:

+		ch = b->parent;

+		if(ch == nil)

+			ch = &root;

+		goto Child;

+	}

+	if(name != nil){

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

+			goto Clone;

-	qlock(&srvlk);

-	if(name != nil)

-		sp = srvlookup(name, -1);

-	else {

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

+		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)

 			s--;

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

+			s--;

 	}

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

-		qunlock(&srvlk);

+	if(sp != nil){

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

+		q.path = SRVQID(sp->path, Qsrv);

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

+	} else if(ch != nil){

+Child:

+		if(name != nil || s == DEVDOTDOT){

+			devpermcheck(ch->owner, ch->perm, OEXEC);

+			c->aux = ch;

+		}

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

+		q.path = SRVQID(ch->path, Qsrv);

+		q.type = QTDIR;

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

+	} else if(0){

+Clone:

+		q.path = SRVQID(SRVPATH(c->qid.path), Qclone);

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

+	} else {

+		runlock(&srvlk);

+		poperror();

 		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);

+

+	runlock(&srvlk);

+	poperror();

 	return 1;

 }

@@ -66,24 +214,55 @@

 static void

 srvinit(void)

 {

-	qidpath = 1;

+	srvpath = 0;

+	root.path = srvpath++;

+	root.name = "#s";

+	root.perm = 0777;

+	kstrdup(&root.owner, eve);

 }

 static Chan*

 srvattach(char *spec)

 {

-	return devattach('s', spec);

+	Chan *c;

+

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

+	c->aux = &root;

+	return c;

 }

 static Walkqid*

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

 {

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

+	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;

 }

 static int

 srvstat(Chan *c, uchar *db, int n)

 {

+	Dir d;

+

+	/* devstat cheats for dir stats, we care about our dir perms */

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

+		srvgen(c, nil, nil, 0, -2, &d);

+		n = convD2M(&d, db, n);

+		if(n == 0)

+			error(Ebadarg);

+		return n;

+	}

+

 	return devstat(c, db, n, 0, 0, srvgen);

 }

@@ -90,12 +269,14 @@

 char*

 srvname(Chan *c)

 {

+	Board *b;

 	Srv *sp;

 	char *s;

 	s = nil;

-	qlock(&srvlk);

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

+	b = &root;

+	rlock(&srvlk);

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

 		if(sp->chan == c){

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

 			if(s != nil)

@@ -103,7 +284,7 @@

 			break;

 		}

 	}

-	qunlock(&srvlk);

+	runlock(&srvlk);

 	return s;

 }

@@ -110,33 +291,74 @@

 static Chan*

 srvopen(Chan *c, int omode)

 {

+	Board *b, *ch;

 	Srv *sp;

 	Chan *nc;

+	char buf[64];

+	if(omode&OTRUNC)

+		error(Eexist);

+	if(omode&ORCLOSE)

+		error(Eperm);

+

+	b = c->aux;

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

+		wlock(&srvlk);

+		if(waserror()){

+			wunlock(&srvlk);

+			nexterror();

+		}

+		if(b->closed)

+			error(Eexpired);

+

+		ch = smalloc(sizeof *ch);

+		ch->ref = 1;

+		ch->perm = 0770;

+		kstrdup(&ch->owner, up->user);

+		do {

+			ch->path = srvpath++;

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

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

+

+		ch->parent = b;

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

+

+		ch->link = b->child;

+		b->child = ch;

+		c->aux = ch;

+		c->qid.path = SRVQID(ch->path, Qlease);

+		c->mode = openmode(omode);

+		boardclunk(b, 0);

+		wunlock(&srvlk);

+		poperror();

+		return c;

+	}

+

+	rlock(&srvlk);

+	if(waserror()){

+		runlock(&srvlk);

+		nexterror();

+	}

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

 		if(omode & ORCLOSE)

 			error(Eperm);

 		if(omode != OREAD)

 			error(Eisdir);

-		c->mode = omode;

+		devpermcheck(b->owner, b->perm, omode);

+		c->mode = openmode(omode);

 		c->flag |= COPEN;

 		c->offset = 0;

+		runlock(&srvlk);

+		poperror();

 		return c;

 	}

-	qlock(&srvlk);

-	if(waserror()){

-		qunlock(&srvlk);

-		nexterror();

-	}

+	if(b->closed)

+		error(Eexpired);

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

+	sp = lookup(b->srv, 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);

@@ -144,7 +366,7 @@

 	nc = sp->chan;

 	incref(nc);

-	qunlock(&srvlk);

+	runlock(&srvlk);

 	poperror();

 	cclose(c);

@@ -154,6 +376,7 @@

 static Chan*

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

 {

+	Board *b;

 	Srv *sp;

 	if(openmode(omode) != OWRITE)

@@ -162,31 +385,40 @@

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

 		error(Etoolong);

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

+		error("reserved name");

+

 	sp = smalloc(sizeof *sp);

 	kstrdup(&sp->name, name);

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

-	qlock(&srvlk);

+	b = c->aux;

+	wlock(&srvlk);

 	if(waserror()){

-		qunlock(&srvlk);

+		wunlock(&srvlk);

 		free(sp->owner);

 		free(sp->name);

 		free(sp);

 		nexterror();

 	}

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

+	if(b->closed)

+		error(Eexpired);

+	devpermcheck(b->owner, b->perm, OWRITE);

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

 		error(Eexist);

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

+		error(Eexist);

 	sp->perm = perm&0777;

-	sp->path = qidpath++;

+	sp->path = srvpath++;

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

+	c->qid.path = SRVQID(sp->path, Qsrv);

 	c->qid.type = QTFILE;

-	sp->link = srv;

-	srv = sp;

+	sp->link = b->srv;

+	b->srv = sp;

-	qunlock(&srvlk);

+	wunlock(&srvlk);

 	poperror();

 	c->flag |= COPEN;

@@ -198,41 +430,35 @@

 static void

 srvremove(Chan *c)

 {

-	Srv *sp, **l;

+	Board *b;

+	Srv *sp;

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

-		error(Eperm);

-

-	qlock(&srvlk);

+	b = c->aux;

+	wlock(&srvlk);

 	if(waserror()){

-		qunlock(&srvlk);

+		boardclunk(b, 0);

+		wunlock(&srvlk);

 		nexterror();

 	}

-	l = &srv;

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

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

-			break;

-		l = &sp->link;

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

+		error(Eperm);

+	switch(SRVTYPE(c->qid.path)){

+	case Qlease:

+	case Qclone:

+		error(Eperm);

 	}

+

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

 	if(sp == nil)

 		error(Enonexist);

-	/*

-	 * Only eve can remove system services.

-	 */

-	if(strcmp(sp->owner, eve) == 0 && !iseve())

+	if(strcmp(sp->owner, up->user) != 0 && !iseve())

 		error(Eperm);

-	/*

-	 * No removing personal services.

-	 */

-	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;

-

-	qunlock(&srvlk);

+	boardclunk(b, 0);

+	wunlock(&srvlk);

 	poperror();

 	if(sp->chan != nil)

@@ -245,12 +471,18 @@

 static int

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

 {

+	Board *b, *s;

 	char *strs;

-	Srv *sp;

 	Dir d;

+	Link *lp;

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

+	switch(SRVTYPE(c->qid.path)){

+	case Qlease:

+	case Qclone:

 		error(Eperm);

+	}

+	if(c->qid.type == QTDIR && c->aux == &root)

+		error(Eperm);

 	strs = smalloc(n);

 	if(waserror()){

@@ -261,32 +493,48 @@

 	if(n == 0)

 		error(Eshortstat);

-	qlock(&srvlk);

+	b = c->aux;

+	wlock(&srvlk);

 	if(waserror()){

-		qunlock(&srvlk);

+		wunlock(&srvlk);

 		nexterror();

 	}

+	if(b->closed)

+		error(Eexpired);

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

-	if(sp == nil)

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

+		lp = b;

+	else

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

+	if(lp == nil)

 		error(Enonexist);

-	if(strcmp(sp->owner, up->user) != 0 && !iseve())

+	if(strcmp(lp->owner, up->user) != 0 && !iseve())

 		error(Eperm);

-	if(d.name != nil && *d.name && strcmp(sp->name, d.name) != 0) {

+	if(d.name != nil && *d.name && strcmp(lp->name, d.name) != 0) {

 		if(strchr(d.name, '/') != nil)

 			error(Ebadchar);

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

 			error(Etoolong);

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

+

+		//Ensure new name doesn't conflict with old names

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

+			s = b->parent;

+		else

+			s = b;

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

+			error(Eexist);

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

+			error(Eexist);

+		kstrdup(&lp->name, d.name);

 	}

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

-		kstrdup(&sp->owner, d.uid);

+		kstrdup(&lp->owner, d.uid);

 	if(d.mode != ~0UL)

-		sp->perm = d.mode & 0777;

+		lp->perm = d.mode & 0777;

-	qunlock(&srvlk);

+	wunlock(&srvlk);

 	poperror();

 	free(strs);

@@ -298,22 +546,48 @@

 static void

 srvclose(Chan *c)

 {

-	/*

-	 * 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){

+	Board *b;

+	int expired;

+

+	expired = 0;

+	if(SRVTYPE(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.

+	 	 */

 		if(waserror())

 			return;

 		srvremove(c);

 		poperror();

+		return;

 	}

+

+	b = c->aux;

+	wlock(&srvlk);

+	boardclunk(b, expired);

+	wunlock(&srvlk);

 }

 static long

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

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

 {

+	Board *b;

+

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

+		b = c->aux;

+		rlock(&srvlk);

+		if(waserror()){

+			runlock(&srvlk);

+			nexterror();

+		}

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

+		runlock(&srvlk);

+		poperror();

+		return n;

+	}

 	isdir(c);

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

 }

@@ -321,11 +595,15 @@

 static long

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

 {

+	Board *b;

 	Srv *sp;

 	Chan *c1;

 	int fd;

 	char buf[32];

+	if(SRVTYPE(c->qid.path) == Qlease)

+		error(Eperm);

+

 	if(n >= sizeof buf)

 		error(Etoobig);

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

@@ -334,15 +612,18 @@

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

-	qlock(&srvlk);

+	b = c->aux;

+	wlock(&srvlk);

 	if(waserror()) {

-		qunlock(&srvlk);

+		wunlock(&srvlk);

 		cclose(c1);

 		nexterror();

 	}

+	if(b->closed)

+		error(Eexpired);

 	if(c1->qid.type & QTAUTH)

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

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

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

 	if(sp == nil)

 		error(Enonexist);

@@ -351,7 +632,7 @@

 	sp->chan = c1;

-	qunlock(&srvlk);

+	wunlock(&srvlk);

 	poperror();

 	return n;

 }

@@ -380,12 +661,15 @@

 void

 srvrenameuser(char *old, char *new)

 {

+	Board *b;

 	Srv *sp;

-	qlock(&srvlk);

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

+	b = &root;

+	wlock(&srvlk);

+	kstrdup(&b->owner, new);

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

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

 			kstrdup(&sp->owner, new);

 	}

-	qunlock(&srvlk);

+	wunlock(&srvlk);

 }