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skel(3) → skelfs(4)

The original intention was to put devskel in to the
kernel to detach what it provides from devsrv.
That is not a good reason, just move it to userspace.

auth/box has been changed to exec skelfs instead
of relying on '#z'.

--- a/sys/man/3/skel

+++ /dev/null

@@ -1,35 +1,0 @@

-.TH SKEL 3 

-.SH NAME

-skel \- skeleton builder

-.SH SYNOPSIS

-.B bind #z/\fIskel\fR

-.I dir

-.PP

-.B bind #zd/\fIskel\fR

-.I dir

-.PP

-.B bind #ze/

-.I dir

-.SH DESCRIPTION

-.PP

-This device serves a single child directory with a single empty child

-file. The name of these files is determined by the first walk away

-from the root. After which, the hierarchy for that attached session

-becomes stable. The

-.B d

-attach option causes the child file to be an empty directory. The 

-.B e

-attach option presents a completly empty root directory.

-.SH EXAMPLES

-Skeleton files can be used for constructing arbitrary bind targets.

-.EX

-.IP

-bind -b '#zd/newroot' /

-bind '#zd/bin' /newroot

-bind '#z/walk' /newroot/bin

-bind /bin/walk /newroot/bin/walk

-bind /newroot /

-walk /

-.EE

-.SH SOURCE

-.B /sys/src/9/port/devskel.c

--- /dev/null

+++ b/sys/man/4/skelfs

@@ -1,0 +1,65 @@

+.TH SKELFS 4

+.SH NAME

+skelfs  \-  build directory skeletons

+.SH SYNOPSIS

+.B skelfs

+[

+.B -i

+]

+[

+.B -t

+.I mode

+]

+[

+.B -s

+.I service

+]

+[

+.I mnt

+]

+.SH DESCRIPTION

+.I Skelfs

+generates directory skeletons

+to assist in building namespaces.

+Skeletons are generated on demand

+by walking through the root directory.

+A skeleon is a directory containing a single empty child.

+The name of this child is defined by the first walk taken

+away from the root. For example the hierarchy for a skeleton

+named 'echo' would be:

+.PP

+.EX

+	/

+	/echo/

+	/echo/echo

+.EE

+.PP

+The

+.I mode

+dictates what form the innermost child file takes. The

+.B file

+and

+.B dir

+modes cause the child to be an empty file or directory

+respecively. The

+.B empty

+mode instead serves no skeletons, causing the root

+directory to always be empty.

+A client may override the mode by providing

+its own selection as an attach option. If a

+mode is not provided,

+.B file

+is assumed.

+.PP

+The skeletons generated by

+.I skelfs

+are anonmyous. Clients will never see the

+skeletons of other clients, nor can a client revisit

+a previous skeleton. 

+.PP

+.SH "SEE ALSO"

+.B auth/box

+in

+.IR auth (8).

+.SH SOURCE

+.B /sys/src/cmd/skelfs.c

--- a/sys/src/9/pc/pc

+++ b/sys/src/9/pc/pc

@@ -18,7 +18,6 @@

 	kprof

 	fs

 	dtracy

-	skel

 	ether		netif

 	bridge		netif log

--- a/sys/src/9/pc64/pc64

+++ b/sys/src/9/pc64/pc64

@@ -41,7 +41,6 @@

 	segment

 	vmx

 	dtracy

-	skel

 link

 #	devpccard	pci

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

+++ /dev/null

@@ -1,239 +1,0 @@

-#include	"u.h"

-#include	"../port/lib.h"

-#include	"mem.h"

-#include	"dat.h"

-#include	"fns.h"

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

-

-#include	"netif.h"

-

-typedef struct Skel Skel;

-struct Skel {

-	RWlock;

-	int ref;

-	char name[KNAMELEN];

-	char mode;

-};

-

-struct

-{

-	QLock;

-	ulong path;

-} skelalloc;

-

-enum{

-	Qroot,

-	Qdir,

-	Qskel,

-};

-

-static Chan*

-skelattach(char *spec)

-{

-	Chan *c;

-	Skel *f;

-	uvlong path;

-

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

-

-	f = mallocz(sizeof *f, 1);

-	if(f == nil)

-		exhausted("memory");

-	if(waserror()){

-		free(f);

-		nexterror();

-	}

-

-	if(spec == nil)

-		f->mode = 'f';

-	else

-		f->mode = spec[0];

-

-	eqlock(&skelalloc);

-	path = skelalloc.path++;

-	qunlock(&skelalloc);

-

-	poperror();

-	mkqid(&c->qid, NETQID(path, Qroot), path, QTDIR);

-	f->ref = 1;

-	c->aux = f;

-	return c;

-}

-

-static int

-step(Chan *c, Dir *dp, int direction)

-{

-	Skel *f;

-	Qid qid;

-	ulong perm;

-	int path;

-	char *name;

-

-	perm = 0555|DMDIR;

-	path = NETTYPE(c->qid.path);

-	f = c->aux;

-	rlock(f);

-	if(waserror()){

-		runlock(f);

-		return -1;

-	}

-	name = f->name;

-

-	path += direction;

-	if(!f->name[0] && path > Qroot)

-		error(Enonexist);

-

-	switch(path){

-	case Qroot-1:

-	case Qroot:

-		mkqid(&qid, Qroot, 0, QTDIR);

-		name = "#z";

-		break;

-	case Qdir:

-		mkqid(&qid, Qdir, 0, QTDIR);

-		break;

-	case Qskel:

-		switch(f->mode){

-		case 'd':

-			mkqid(&qid, Qskel, 0, QTDIR);

-			break;

-		case 'f':

-		default:

-			mkqid(&qid, Qskel, 0, QTFILE);

-			perm = 0666;

-			break;

-		}

-		break;

-	default:

-		error(Enonexist);

-	}

-

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

-	qid.path = NETQID(qid.vers, qid.path);

-	devdir(c, qid, name, 0, eve, perm, dp);

-	runlock(f);

-	poperror();

-	return 1;

-}

-

-

-static int

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

-{

-	Skel *f;

-

-	switch(s){

-	case DEVDOTDOT:

-		break;

-	case 0:

-		s++;

-		break;

-	default:

-		return -1;

-	}

-	f = c->aux;

-	if(name && NETTYPE(c->qid.path) == Qroot){

-		wlock(f);

-		if(!f->name[0] && f->mode != 'e')

-			utfecpy(f->name, &f->name[sizeof f->name-1], name);

-		wunlock(f);

-	}

-

-	return step(c, dp, s);

-}

-

-static Walkqid*

-skelwalk(Chan *c, Chan *nc, char **name, int nname)

-{

-	Walkqid *wq;

-	Skel *f;

-

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

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

-		return wq;

-

-	f = c->aux;

-	wlock(f);

-	if(f->ref <= 0)

-		panic("devskel ref");

-	f->ref++;

-	wunlock(f);

-	return wq;

-}

-

-static Chan*

-skelopen(Chan *c, int omode)

-{

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

-		error(Eperm);

-	if(omode != OREAD)

-		error(Ebadarg);

-

-	c->mode = omode;

-	c->flag |= COPEN;

-	c->offset = 0;

-	return c;

-}

-

-static void

-skelclose(Chan *c)

-{

-	Skel *f;

-

-	f = c->aux;

-	wlock(f);

-	f->ref--;

-	if(f->ref == 0){

-		wunlock(f);

-		free(f);

-	} else

-		wunlock(f);

-}

-

-static long

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

-{

-	return devdirread(c, va, n, nil, 0, skelgen);

-}

-

-static long

-skelwrite(Chan*, void*, long, vlong)

-{

-	error(Ebadusefd);

-	return -1;

-}

-

-static int

-skelstat(Chan *c, uchar *db, int n)

-{

-	Dir dir;

-

-	if(step(c, &dir, 0) < 0)

-		error(Enonexist);

-

-	n = convD2M(&dir, db, n);

-	if(n < BIT16SZ)

-		error(Eshortstat);

-	return n;

-}

-

-Dev skeldevtab = {

-	'z',

-	"skel",

-

-	devreset,

-	devinit,

-	devshutdown,

-	skelattach,

-	skelwalk,

-	skelstat,

-	skelopen,

-	devcreate,

-	skelclose,

-	skelread,

-	devbread,

-	skelwrite,

-	devbwrite,

-	devremove,

-	devwstat,

-};

--- a/sys/src/cmd/auth/box.c

+++ b/sys/src/cmd/auth/box.c

@@ -29,7 +29,7 @@

 			dash[1] = 'a';

 			break;

 		}

-		print("bind %s %s %s\n", dash, new, old);

+		fprint(2, "bind %s %s %s\n", dash, new, old);

 	}

 	if(bind(new, old, flag) < 0)

 		sysfatal("bind: %r");

@@ -72,10 +72,10 @@

 	Dir *d;

 	int i, j, n;

-	snprint(rootskel, sizeof rootskel, "#zd/newroot.%d", getpid());

+	snprint(rootskel, sizeof rootskel, "/mnt/d/newroot.%d", getpid());

 	binderr(rootskel, "/", MBEFORE);

-	newroot = rootskel + strlen("#zd");

+	newroot = rootskel + strlen("/mnt/d");

 	for(j = 0; j < nname; j++){

 		if(names[j] == nil)

@@ -97,9 +97,9 @@

 			if(d == nil)

 				continue;

 			if(d->mode & DMDIR)

-				snprint(skel, sizeof skel, "#zd/%s", parts[i]);

+				snprint(skel, sizeof skel, "/mnt/d/%s", parts[i]);

 			else

-				snprint(skel, sizeof skel, "#zf/%s", parts[i]);

+				snprint(skel, sizeof skel, "/mnt/f/%s", parts[i]);

 			free(d);

 			binderr(skel, dir, MBEFORE);

 		}

@@ -109,6 +109,31 @@

 }

 void

+skelfs(void)

+{

+	int p[2];

+	int dfd;

+

+	pipe(p);

+	switch(rfork(RFFDG|RFREND|RFPROC|RFNAMEG)){

+	case -1:

+		sysfatal("fork");

+	case 0:

+		close(p[1]);

+		dup(p[0], 0);

+		dup(p[0], 1);

+		execl("/bin/skelfs", "skelfs", debug > 1 ? "-Di" : "-i", nil);

+		sysfatal("exec /bin/skelfs: %r");

+	}

+	close(p[0]);

+	dfd = dup(p[1], -1);

+	if(mount(p[1], -1, "/mnt/f", MREPL, "file") < 0)

+		sysfatal("/mnt/f mount setup: %r");

+	if(mount(dfd, -1, "/mnt/d", MREPL, "dir") < 0)

+		sysfatal("/mnt/d mount setup: %r");

+}

+

+void

 usage(void)

 {

 	fprint(2, "usage %s: [ -d ] [ -r file ] [ -c dir ] [ -e devs ] cmd args...\n", argv0);

@@ -129,8 +154,10 @@

 	nparts = 0;

 	memset(devs, 0, sizeof devs);

 	ARGBEGIN{

+	case 'D':

+		debug++;

 	case 'd':

-		debug = 1;

+		debug++;

 		break;

 	case 'r':

 		parts[nparts] = EARGF(usage());

@@ -164,6 +191,7 @@

 	argv[0] = b;

 	rfork(RFNAMEG|RFFDG);

+	skelfs();

 	dfd = open("/dev/drivers", OWRITE|OCEXEC);

 	if(dfd < 0)

 		sysfatal("could not /dev/drivers: %r");

@@ -172,7 +200,7 @@

 	sandbox(parts, mflags, nparts);

 	if(debug)

-		print("chdev %s\n", devs);

+		fprint(2, "chdev %s\n", devs);

 	if(devs[0] != '\0'){

 		if(fprint(dfd, "chdev & %s", devs) <= 0)

--- /dev/null

+++ b/sys/src/cmd/skelfs.c

@@ -1,0 +1,251 @@

+#include <u.h>

+#include <libc.h>

+#include <fcall.h>

+#include <thread.h>

+#include <9p.h>

+

+typedef struct Skel Skel;

+struct Skel {

+	char name[64];

+	char mode;

+};

+

+static uvlong 	sessions;

+static char	defmode;

+

+enum{

+	Qroot,

+	Qdir,

+	Qskel,

+};

+

+#define qtype(x)	(((ulong)x)&0x1f)

+#define qsess(x)	((((ulong)x))>>5)

+#define mkqid(i,t)	((((ulong)i)<<5)|(t))

+

+static int

+step(Fid *f, int way, Qid *res, Dir *dp)

+{

+	Skel *s;

+	int path;

+	char *name;

+	ulong perm;

+

+	s = f->aux;

+	name = s->name;

+	perm = 0550|DMDIR;

+	path = qtype(f->qid.path) + way;

+	if(!name[0] && way > 0)

+		return -1;

+

+	if(path < 0)

+		goto Root;

+	switch(path){

+	Root:

+	case Qroot:

+		name = "/";

+		/* fallthrough */

+	case Qdir:

+		res->type = QTDIR;

+		break;

+	case Qskel:

+		switch(s->mode){

+		case 'd':

+			res->type = QTDIR;

+			break;

+		case 'f':

+		default:

+			res->type = QTFILE;

+			perm = 0;

+			break;

+		}

+		break;

+	default:

+		return -1;

+	}

+	res->vers = qsess(f->qid.path);

+	res->path = mkqid(res->vers, path);

+	if(dp){

+		dp->mode = perm;

+		dp->name = estrdup9p(name);

+		dp->uid = estrdup9p("sys");

+		dp->gid = estrdup9p("sys");

+		dp->qid = *res;

+		dp->length = 0;

+	}

+	return 1;

+}

+

+static int

+dirgen(int i, Dir *d, void *a)

+{

+	Fid *f;

+	Qid q;

+

+	if(i > 0)

+		return -1;

+	f = a;

+	return step(f, 1, &q, d);

+}

+

+static void

+fidclunk(Fid *fid)

+{

+	free(fid->aux);

+}

+

+static char*

+fsclone(Fid *old, Fid *new, void*)

+{

+	Skel *s, *s2;

+

+	s = old->aux;

+	s2 = emalloc9p(sizeof *s2);

+	if(s2 == nil)

+		return "out of memory";

+	memset(s2, 0, sizeof *s2);

+

+	s2->mode = s->mode;

+	utfecpy(s2->name, &s2->name[sizeof s2->name-1], s->name);

+	new->aux = s2;

+	return nil;

+}

+

+static char*

+fswalk1(Fid *old, char *name, void*)

+{

+	Skel *s;

+

+	if(strcmp("..", name) == 0){

+		step(old, -1, &old->qid, nil);

+		return nil;

+	}

+

+	s = old->aux;

+	if(!s->name[0] && qtype(old->qid.path) == Qroot && s->mode != 'e'){

+		utfecpy(s->name, &s->name[sizeof s->name-1], name);

+		old->qid.vers = sessions++;

+		old->qid.path = mkqid(old->qid.vers, qtype(old->qid.path));

+	} else if(strcmp(name, s->name) != 0)

+		return "does not exist";

+

+	if(step(old, 1, &old->qid, nil) < 0)

+		return "does not exist";

+

+	return nil;

+}

+

+static void

+fswalk(Req *r)

+{

+	walkandclone(r, fswalk1, fsclone, nil);

+}

+

+static void

+fsattach(Req *r)

+{

+	Skel s;

+	Fid root;

+	char *spec;

+	Qid *q;

+

+	spec = r->ifcall.aname;

+	if(spec && spec[0] != '\0')

+		s.mode = spec[0];

+	else

+		s.mode = defmode;

+

+	q = &r->fid->qid;

+	q->vers = sessions++;

+	q->path = mkqid(q->vers, Qroot);

+	q->type = QTDIR;

+	r->ofcall.qid = *q;

+

+	s.name[0] = '\0';

+	root.aux = &s;

+	respond(r, fsclone(&root, r->fid, nil));

+}

+

+static void

+fsstat(Req *r)

+{

+	Qid q;

+

+	if(step(r->fid, 0, &q, &r->d) < 0)

+		respond(r, "does not exist");

+	respond(r, nil);

+}

+

+static void

+fsread(Req *r)

+{

+	dirread9p(r, dirgen, r->fid);

+	respond(r, nil);

+}

+

+static void

+fsopen(Req *r)

+{

+	r->ofcall.mode = r->ifcall.mode;

+	if(r->ifcall.mode != OREAD)

+		respond(r, "permission denied");

+	else

+		respond(r, nil);

+}

+

+Srv fs=

+{

+.attach=	fsattach,

+.open=		fsopen,

+.read=		fsread,

+.stat=		fsstat,

+.walk=		fswalk,

+.destroyfid=	fidclunk

+};

+

+void

+usage(void)

+{

+	fprint(2, "usage: %s [ -Di ] [ -s service ] [ -t mode ] [ mntpt ]\n", argv0);

+	exits("usage");

+}

+

+void

+main(int argc, char **argv)

+{

+	char *s, *mode;

+	int stdio;

+

+	s = nil;

+	stdio = 0;

+	defmode = 'f';

+	ARGBEGIN{

+	case 'D':

+		chatty9p++;

+		break;

+	case 's':

+		s = EARGF(usage());

+		break;

+	case 'i':

+		stdio = 1;

+		break;

+	case 't':

+		mode = EARGF(usage());

+		defmode = mode[0];

+		break;

+	default:

+		usage();

+	}ARGEND

+

+	if(argc > 1)

+		usage();

+

+	if(stdio == 0){

+		postmountsrv(&fs, s, argc ? argv[0] : "/mnt/skel", MREPL);

+		exits(nil);

+	}

+	fs.infd = 0;

+	fs.outfd = 1;

+	srv(&fs);

+	exits(nil);

+}