ref: d1540c7f666e3c5d636b48c956b444205b50502d
dir: /appl/cmd/lockfs.b/
implement Lockfs;
include "sys.m";
sys: Sys;
stderr: ref Sys->FD;
include "draw.m";
include "styx.m";
styx: Styx;
Tmsg, Rmsg: import styx;
include "styxlib.m";
styxlib: Styxlib;
Dirtab, Styxserver, Chan,
devdir,
Eperm, Ebadfid, Eexists, Enotdir, Enotfound, Einuse: import styxlib;
include "arg.m";
include "keyring.m";
keyring: Keyring;
include "security.m";
auth: Auth;
include "dial.m";
dial: Dial;
Lockfs: module {
init: fn(nil: ref Draw->Context, argv: list of string);
dirgen: fn(srv: ref Styxlib->Styxserver, c: ref Styxlib->Chan,
tab: array of Styxlib->Dirtab, i: int): (int, Sys->Dir);
};
Elocked: con "file is locked";
devgen: Dirgenmod;
Openreq: adt {
srv: ref Styxserver;
tag: int;
omode: int;
c: ref Chan;
uproc: Uproc;
};
Lockqueue: adt {
h: list of ref Openreq;
t: list of ref Openreq;
put: fn(q: self ref Lockqueue, s: ref Openreq);
get: fn(q: self ref Lockqueue): ref Openreq;
peek: fn(q: self ref Lockqueue): ref Openreq;
flush: fn(q: self ref Lockqueue, srv: ref Styxserver, tag: int);
};
Lockfile: adt {
waitq: ref Lockqueue;
fd: ref Sys->FD;
readers: int;
writers: int;
d: Sys->Dir;
};
Ureq: adt {
fname: string;
pick {
Open =>
omode: int;
Create =>
omode: int;
perm: int;
Remove =>
Wstat =>
dir: Sys->Dir;
}
};
Uproc: type chan of (ref Ureq, chan of (ref Sys->FD, string));
maxqidpath := big 1;
locks: list of ref Lockfile;
lockdir: string;
authinfo: ref Keyring->Authinfo;
timefd: ref Sys->FD;
MAXCONN: con 20;
verbose := 0;
usage()
{
sys->fprint(stderr, "usage: lockfs [-A] [-a alg]... [-p addr] dir [mountpoint]\n");
raise "fail:usage";
}
badmodule(p: string)
{
sys->fprint(stderr, "lockfs: cannot load %s: %r\n", p);
raise "fail:bad module";
}
init(nil: ref Draw->Context, argv: list of string)
{
sys = load Sys Sys->PATH;
stderr = sys->fildes(2);
styx = load Styx Styx->PATH;
if (styx == nil)
badmodule(Styx->PATH);
dial = load Dial Dial->PATH;
if (dial == nil)
badmodule(Dial->PATH);
styx->init();
styxlib = load Styxlib Styxlib->PATH;
if (styxlib == nil)
badmodule(Styxlib->PATH);
styxlib->init(styx);
devgen = load Dirgenmod "$self";
if (devgen == nil)
badmodule("self as Dirgenmod");
timefd = sys->open("/dev/time", sys->OREAD);
if (timefd == nil) {
sys->fprint(stderr, "lockfs: cannot open /dev/time: %r\n");
raise "fail:no time";
}
arg := load Arg Arg->PATH;
if (arg == nil)
badmodule(Arg->PATH);
arg->init(argv);
addr := "";
doauth := 1;
algs: list of string;
while ((opt := arg->opt()) != 0) {
case opt {
'p' =>
addr = arg->arg();
'a' =>
alg := arg->arg();
if (alg == nil)
usage();
algs = alg :: algs;
'A' =>
doauth = 0;
'v' =>
verbose = 1;
* =>
usage();
}
}
argv = arg->argv();
if (argv == nil || (addr != nil && tl argv != nil))
usage();
if (addr == nil)
doauth = 0; # no authentication necessary for local mount
if (doauth) {
auth = load Auth Auth->PATH;
if (auth == nil)
badmodule(Auth->PATH);
if ((e := auth->init()) != nil) {
sys->fprint(stderr, "lockfs: cannot init auth: %s\n", e);
raise "fail:errors";
}
keyring = load Keyring Keyring->PATH;
if (keyring == nil)
badmodule(Keyring->PATH);
authinfo = keyring->readauthinfo("/usr/" + user() + "/keyring/default");
}
mountpoint := lockdir = hd argv;
if (tl argv != nil)
mountpoint = hd tl argv;
if (addr != nil) {
if (doauth && algs == nil)
algs = "none" :: nil; # XXX is this default a bad idea?
srvrq := chan of (ref Sys->FD, string, Uproc);
srvsync := chan of (int, string);
spawn listener(addr, srvrq, srvsync, algs);
(srvpid, err) := <-srvsync;
srvsync = nil;
if (srvpid == -1) {
sys->fprint(stderr, "lockfs: failed to start listener: %s\n", err);
raise "fail:errors";
}
sync := chan of int;
spawn server(srvrq, sync);
<-sync;
} else {
rq := chan of (ref Sys->FD, string, Uproc);
fds := array[2] of ref Sys->FD;
sys->pipe(fds);
sync := chan of int;
spawn server(rq, sync);
<-sync;
rq <-= (fds[0], "lock", nil);
rq <-= (nil, nil, nil);
if (sys->mount(fds[1], nil, mountpoint, Sys->MREPL | Sys->MCREATE, nil) == -1) {
sys->fprint(stderr, "lockfs: cannot mount: %r\n");
raise "fail:cannot mount";
}
}
}
server(srvrq: chan of (ref Sys->FD, string, Uproc), sync: chan of int)
{
sys->pctl(Sys->FORKNS, nil);
sync <-= 1;
down := 0;
nclient := 0;
tchans := array[MAXCONN] of chan of ref Tmsg;
srv := array[MAXCONN] of ref Styxserver;
uprocs := array[MAXCONN] of Uproc;
lockinit();
Service:
for (;;) alt {
(fd, reqstr, uprocch) := <-srvrq =>
if (fd == nil) {
if (verbose && reqstr != nil)
sys->print("lockfs: localserver going down (reason: %s)\n", reqstr);
down = 1;
} else {
if (verbose)
sys->print("lockfs: got new connection (s == '%s')\n", reqstr);
for (i := 0; i < len tchans; i++)
if (tchans[i] == nil) {
(tchans[i], srv[i]) = Styxserver.new(fd);
if(verbose)
sys->print("svc started\n");
uprocs[i] = uprocch;
break;
}
if (i == len tchans) {
sys->fprint(stderr, "lockfs: too many clients\n"); # XXX expand arrays
if (uprocch != nil)
uprocch <-= (nil, nil);
} else
nclient++;
}
(n, gm) := <-tchans =>
if (handletmsg(srv[n], gm, uprocs[n]) == -1) {
tchans[n] = nil;
srv[n] = nil;
if (uprocs[n] != nil) {
uprocs[n] <-= (nil, nil);
uprocs[n] = nil;
}
if (nclient-- <= 1 && down)
break Service;
}
}
if (verbose)
sys->print("lockfs: finished\n");
}
dirgen(nil: ref Styxserver, nil: ref Styxlib->Chan,
nil: array of Dirtab, s: int): (int, Sys->Dir)
{
d: Sys->Dir;
ll := locks;
for (i := 0; i < s && ll != nil; i++)
ll = tl ll;
if (ll == nil)
return (-1, d);
return (1, (hd ll).d);
}
handletmsg(srv: ref Styxserver, gm: ref Tmsg, uproc: Uproc): int
{
{
if (gm == nil)
gm = ref Tmsg.Readerror(-1, "eof");
if(verbose)
sys->print("<- %s\n", gm.text());
pick m := gm {
Readerror =>
# could be more efficient...
for (cl := srv.chanlist(); cl != nil; cl = tl cl) {
c := hd cl;
for (ll := locks; ll != nil; ll = tl ll) {
if ((hd ll).d.qid.path == c.qid.path) {
l := hd ll;
l.waitq.flush(srv, -1);
if (c.open)
unlocked(l);
break;
}
}
}
if (m.error != "eof")
sys->fprint(stderr, "lockfs: read error: %s\n", m.error);
return -1;
Version =>
srv.devversion(m);
Auth =>
srv.devauth(m);
Walk =>
c := fid2chan(srv, m.fid);
qids: array of Sys->Qid;
cc := ref *c;
if (len m.names > 0) {
qids = array[1] of Sys->Qid; # it's just one level
if ((cc.qid.qtype & Sys->QTDIR) == 0) {
srv.reply(ref Rmsg.Error(m.tag, Enotdir));
break;
}
for (ll := locks; ll != nil; ll = tl ll)
if ((hd ll).d.name == m.names[0])
break;
if (ll == nil) {
srv.reply(ref Rmsg.Error(m.tag, Enotfound));
break;
}
d := (hd ll).d;
cc.qid = d.qid;
cc.path = d.name;
qids[0] = c.qid;
}
if(m.newfid != m.fid){
nc := srv.clone(cc, m.newfid);
if(nc == nil){
srv.reply(ref Rmsg.Error(m.tag, Einuse));
break;
}
}else{
c.qid = cc.qid;
c.path = cc.path;
}
srv.reply(ref Rmsg.Walk(m.tag, qids));
Open =>
c := fid2chan(srv, m.fid);
if (c.qid.qtype & Sys->QTDIR) {
srv.reply(ref Rmsg.Open(m.tag, c.qid, Styx->MAXFDATA));
break;
}
for (ll := locks; ll != nil; ll = tl ll)
if ((hd ll).d.qid.path == c.qid.path)
break;
if (ll == nil) {
srv.reply(ref Rmsg.Error(m.tag, Enotfound));
break;
}
l := hd ll;
req := ref Openreq(srv, m.tag, m.mode, c, uproc);
if (l.fd == nil || (m.mode == Sys->OREAD && l.writers == 0)) {
openlockfile(l, req);
} else {
l.waitq.put(req);
}
req = nil;
Create =>
c := fid2chan(srv, m.fid);
if ((c.qid.qtype & Sys->QTDIR) == 0) {
srv.reply(ref Rmsg.Error(m.tag, Enotdir));
break;
}
if (m.perm & Sys->DMDIR) {
srv.reply(ref Rmsg.Error(m.tag, Eperm));
break;
}
for (ll := locks; ll != nil; ll = tl ll)
if ((hd ll).d.name == m.name)
break;
if (ll != nil) {
srv.reply(ref Rmsg.Error(m.tag, Eexists));
break;
}
(fd, err) := create(uproc, lockdir + "/" + m.name, m.mode, m.perm);
if (fd == nil) {
srv.reply(ref Rmsg.Error(m.tag, err));
break;
}
(ok, d) := sys->fstat(fd);
if (ok == -1) {
srv.reply(ref Rmsg.Error(m.tag, sys->sprint("%r")));
break;
}
l := ref Lockfile(ref Lockqueue, fd, 0, 0, d);
l.d.qid = (maxqidpath++, 0, Sys->QTFILE);
l.d.mtime = l.d.atime = now();
if (m.mode == Sys->OREAD)
l.readers = 1;
else
l.writers = 1;
locks = l :: locks;
c.qid.path = (hd locks).d.qid.path;
c.open = 1;
srv.reply(ref Rmsg.Create(m.tag, c.qid, Styx->MAXFDATA));
Read =>
c := fid2chan(srv, m.fid);
if (c.qid.qtype & Sys->QTDIR)
srv.devdirread(m, devgen, nil);
else {
l := qid2lock(c.qid);
if (l == nil)
srv.reply(ref Rmsg.Error(m.tag, Enotfound));
else {
d := array[m.count] of byte;
sys->seek(l.fd, m.offset, Sys->SEEKSTART);
n := sys->read(l.fd, d, m.count);
if (n == -1)
srv.reply(ref Rmsg.Error(m.tag, sys->sprint("%r")));
else {
srv.reply(ref Rmsg.Read(m.tag, d[0:n]));
l.d.atime = now();
}
}
}
Write =>
c := fid2chan(srv, m.fid);
if (c.qid.qtype & Sys->QTDIR) {
srv.reply(ref Rmsg.Error(m.tag, Eperm));
break;
}
l := qid2lock(c.qid);
if (l == nil) {
srv.reply(ref Rmsg.Error(m.tag, Enotfound));
break;
}
sys->seek(l.fd, m.offset, Sys->SEEKSTART);
n := sys->write(l.fd, m.data, len m.data);
if (n == -1)
srv.reply(ref Rmsg.Error(m.tag, sys->sprint("%r")));
else {
srv.reply(ref Rmsg.Write(m.tag, n));
nlength := m.offset + big n;
if (nlength > l.d.length)
l.d.length = nlength;
l.d.mtime = now();
l.d.qid.vers++;
}
Clunk =>
c := srv.devclunk(m);
if (c != nil && c.open && (l := qid2lock(c.qid)) != nil)
unlocked(l);
Flush =>
for (ll := locks; ll != nil; ll = tl ll)
(hd ll).waitq.flush(srv, m.tag);
srv.reply(ref Rmsg.Flush(m.tag));
Stat =>
srv.devstat(m, devgen, nil);
Remove =>
c := fid2chan(srv, m.fid);
srv.chanfree(c);
if (c.qid.qtype & Sys->QTDIR) {
srv.reply(ref Rmsg.Error(m.tag, Eperm));
break;
}
l := qid2lock(c.qid);
if (l == nil) {
srv.reply(ref Rmsg.Error(m.tag, Enotfound));
break;
}
if (l.fd != nil) {
srv.reply(ref Rmsg.Error(m.tag, Elocked));
break;
}
if ((err := remove(uproc, lockdir + "/" + l.d.name)) == nil) {
srv.reply(ref Rmsg.Error(m.tag, err));
break;
}
ll: list of ref Lockfile;
for (; locks != nil; locks = tl locks)
if (hd locks != l)
ll = hd locks :: ll;
locks = ll;
srv.reply(ref Rmsg.Remove(m.tag));
Wstat =>
c := fid2chan(srv, m.fid);
if (c.qid.qtype & Sys->QTDIR) {
srv.reply(ref Rmsg.Error(m.tag, Eperm));
break;
}
l := qid2lock(c.qid);
if (l == nil) {
srv.reply(ref Rmsg.Error(m.tag, Enotfound));
break;
}
if ((err := wstat(uproc, lockdir + "/" + l.d.name, m.stat)) != nil) {
srv.reply(ref Rmsg.Error(m.tag, err));
break;
}
(ok, d) := sys->stat(lockdir + "/" + m.stat.name);
if (ok == -1) {
srv.reply(ref Rmsg.Error(m.tag, sys->sprint("%r")));
break;
}
d.qid = l.d.qid;
l.d = d;
srv.reply(ref Rmsg.Wstat(m.tag));
Attach =>
srv.devattach(m);
}
return 0;
}
exception e{
"panic:*" =>
sys->fprint(stderr, "lockfs: %s\n", e);
srv.reply(ref Rmsg.Error(gm.tag, e[len "panic:":]));
return 0;
}
}
unlocked(l: ref Lockfile)
{
if (l.readers > 0)
l.readers--;
else
l.writers--;
if (l.readers > 0)
return;
l.fd = nil;
# unblock all readers at the head of the queue.
# XXX should we queuejump other readers?
while ((nreq := l.waitq.peek()) != nil && l.writers == 0) {
if (nreq.omode != Sys->OREAD && l.readers > 0)
break;
openlockfile(l, nreq);
l.waitq.get();
}
}
openlockfile(l: ref Lockfile, req: ref Openreq): int
{
err: string;
(l.fd, err) = open(req.uproc, lockdir + "/" + l.d.name, req.omode);
if (l.fd == nil) {
req.srv.reply(ref Rmsg.Error(req.tag, err));
return -1;
}
req.c.open = 1;
if (req.omode & Sys->OTRUNC)
l.d.length = big 0;
req.srv.reply(ref Rmsg.Open(req.tag, l.d.qid, Styx->MAXFDATA));
if (req.omode == Sys->OREAD)
l.readers++;
else
l.writers++;
return 0;
}
qid2lock(q: Sys->Qid): ref Lockfile
{
for (ll := locks; ll != nil; ll = tl ll)
if ((hd ll).d.qid.path == q.path)
return hd ll;
return nil;
}
lockinit()
{
fd := sys->open(lockdir, Sys->OREAD);
if (fd == nil)
return;
lockl: list of ref Lockfile;
# XXX if O(n²) behaviour is a problem, use Readdir module
for(;;){
(n, e) := sys->dirread(fd);
if(n <= 0)
break;
for (i := 0; i < n; i++) {
for (l := lockl; l != nil; l = tl l)
if ((hd l).d.name == e[i].name)
break;
if (l == nil) {
e[i].qid = (maxqidpath++, 0, Sys->QTFILE);
lockl = ref Lockfile(ref Lockqueue, nil, 0, 0, e[i]) :: lockl;
}
}
}
# remove all directories from list
for (locks = nil; lockl != nil; lockl = tl lockl)
if (((hd lockl).d.mode & Sys->DMDIR) == 0)
locks = hd lockl :: locks;
}
fid2chan(srv: ref Styxserver, fid: int): ref Chan
{
c := srv.fidtochan(fid);
if (c == nil)
raise "panic:bad fid";
return c;
}
Lockqueue.put(q: self ref Lockqueue, s: ref Openreq)
{
q.t = s :: q.t;
}
Lockqueue.get(q: self ref Lockqueue): ref Openreq
{
s: ref Openreq;
if(q.h == nil)
(q.h, q.t) = (revrqlist(q.t), nil);
if(q.h != nil)
(s, q.h) = (hd q.h, tl q.h);
return s;
}
Lockqueue.peek(q: self ref Lockqueue): ref Openreq
{
s := q.get();
if (s != nil)
q.h = s :: q.h;
return s;
}
doflush(l: list of ref Openreq, srv: ref Styxserver, tag: int): list of ref Openreq
{
oldl := l;
nl: list of ref Openreq;
doneone := 0;
while (l != nil) {
oreq := hd l;
if (oreq.srv != srv || (tag != -1 && oreq.tag != tag))
nl = oreq :: nl;
else
doneone = 1;
l = tl l;
}
if (doneone)
return revrqlist(nl);
else
return oldl;
}
Lockqueue.flush(q: self ref Lockqueue, srv: ref Styxserver, tag: int)
{
q.h = doflush(q.h, srv, tag);
q.t = doflush(q.t, srv, tag);
}
# or inline
revrqlist(ls: list of ref Openreq) : list of ref Openreq
{
rs: list of ref Openreq;
while(ls != nil){
rs = hd ls :: rs;
ls = tl ls;
}
return rs;
}
# addr should be, e.g. tcp!*!2345
listener(addr: string, ch: chan of (ref Sys->FD, string, Uproc),
sync: chan of (int, string), algs: list of string)
{
addr = dial->netmkaddr(addr, "tcp", "33234");
c := dial->announce(addr);
if (c == nil) {
sync <-= (-1, sys->sprint("cannot anounce on %s: %r", addr));
return;
}
sync <-= (sys->pctl(0, nil), nil);
for (;;) {
nc := dial->listen(c);
if (nc == nil) {
ch <-= (nil, sys->sprint("listen failed: %r"), nil);
return;
}
dfd := sys->open(nc.dir + "/data", Sys->ORDWR);
if (dfd != nil) {
if (algs == nil)
ch <-= (dfd, nil, nil);
else
spawn authenticator(dfd, ch, algs);
}
}
}
# authenticate a connection, setting the user id appropriately,
# and then act as a server, performing file operations
# on behalf of the central process.
authenticator(dfd: ref Sys->FD, ch: chan of (ref Sys->FD, string, Uproc), algs: list of string)
{
(fd, err) := auth->server(algs, authinfo, dfd, 1);
if (fd == nil) {
if (verbose)
sys->fprint(stderr, "lockfs: authentication failed: %s\n", err);
return;
}
uproc := chan of (ref Ureq, chan of (ref Sys->FD, string));
ch <-= (fd, err, uproc);
for (;;) {
(req, reply) := <-uproc;
if (req == nil)
exit;
reply <-= doreq(req);
}
}
create(uproc: Uproc, file: string, omode: int, perm: int): (ref Sys->FD, string)
{
return proxydoreq(uproc, ref Ureq.Create(file, omode, perm));
}
open(uproc: Uproc, file: string, omode: int): (ref Sys->FD, string)
{
return proxydoreq(uproc, ref Ureq.Open(file, omode));
}
remove(uproc: Uproc, file: string): string
{
return proxydoreq(uproc, ref Ureq.Remove(file)).t1;
}
wstat(uproc: Uproc, file: string, d: Sys->Dir): string
{
return proxydoreq(uproc, ref Ureq.Wstat(file, d)).t1;
}
proxydoreq(uproc: Uproc, req: ref Ureq): (ref Sys->FD, string)
{
if (uproc == nil)
return doreq(req);
reply := chan of (ref Sys->FD, string);
uproc <-= (req, reply);
return <-reply;
}
doreq(greq: ref Ureq): (ref Sys->FD, string)
{
fd: ref Sys->FD;
err: string;
pick req := greq {
Open =>
if ((fd = sys->open(req.fname, req.omode)) == nil)
err = sys->sprint("%r");
Create =>
if ((fd = sys->create(req.fname, req.omode, req.perm)) == nil)
err = sys->sprint("%r");
Remove =>
if (sys->remove(req.fname) == -1)
err = sys->sprint("%r");
Wstat =>
if (sys->wstat(req.fname, req.dir) == -1)
err = sys->sprint("%r");
}
return (fd, err);
}
user(): string
{
fd := sys->open("/dev/user", sys->OREAD);
if(fd == nil){
sys->fprint(stderr, "lockfs: can't open /dev/user: %r\n");
raise "fail:no user";
}
buf := array[Sys->NAMEMAX] of byte;
n := sys->read(fd, buf, len buf);
if(n < 0) {
sys->fprint(stderr, "lockfs: failed to read /dev/user: %r\n");
raise "fail:no user";
}
return string buf[0:n];
}
now(): int
{
buf := array[128] of byte;
sys->seek(timefd, big 0, 0);
if ((n := sys->read(timefd, buf, len buf)) < 0)
return 0;
return int (big string buf[0:n] / big 1000000);
}