shithub: ridefs

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Fix race condition on r/w forks

--- a/ridefs.c

+++ b/ridefs.c

@@ -34,7 +34,7 @@

 		Qclone,

 		Qclient,

 			Qctl,

-			Qio,

+			Qdata,

 			Qinfo,

 	QCOUNT

 };

@@ -45,7 +45,7 @@

 		"clone",

 		nil,

 			"ctl",

-			"io",

+			"data",

 			"info",

 };

@@ -228,7 +228,7 @@

 rideinit(char *addr, int *fd, int *cfd, char **info){

 	int i;

 	char *b;

-	JSON *j;

+	JSON *j, *v;

 	JSONEl *d;

 	b = netmkaddr(addr, "tcp", defport);

@@ -258,7 +258,8 @@

 	free(b);

 	if(j == nil || j->t != JSONArray || nil == j->first)

 		return "unrecognized reply";

-	if(nil == (b = jsonstr(j->first->val)) || 0 != strcmp(b, "ReplyIdentify"))

+	v = j->first->val;

+	if(v->t != JSONString || 0 != strcmp(v->s, "ReplyIdentify"))

 		return "unexpected identification reply";

 	if(nil == (d = j->first->next) || d->val->t != JSONObject)

 		return "malformed identification reply";

@@ -343,13 +344,13 @@

 	switch(kind){

 	case Qrctl:   d->mode = 0666; break;

 	case Qctl:

-	case Qio:     d->mode = 0666; break;

+	case Qdata:     d->mode = 0666; break;

 	}

 	switch(kind){

 	case Qrctl: d->length = strlen(qrctl); break;

 	case Qctl: d->length = strlen(c->qctl); break;

-	case Qio: d->length = 0; break;

+	case Qdata: d->length = 0; break;

 	case Qinfo: d->length = strlen(c->qinfo); break;

 	}

 }

@@ -429,7 +430,6 @@

 static void

 fsopen(Req *r){

-	int pid;

 	char *err;

 	Rfid *f;

 	Client *c;

@@ -451,32 +451,33 @@

 		respond(r, nil);

 		break;

-	case Qio:

+	case Qdata:

 		if(nil == c->addr){

 			respond(r, "no server set");

 			return;

 		}

-		switch(pid = rfork(RFPROC|RFNOWAIT|RFMEM)){

+		qlock(c);

+		incref(&r->ref);

+		c->req = r;

+		switch(c->pid = rfork(RFPROC|RFNOWAIT|RFMEM)){

 		case 0:

-			qlock(c);

-			if(c->fd)

-				goto end;

-

-			err = rideinit(c->addr, &c->fd, &c->cfd, &c->qinfo);

+			if(!c->fd)

+				err = rideinit(c->addr, &c->fd, &c->cfd, &c->qinfo);

 			c->pid = 0;

 			c->req = nil;

-

-			end:

+			decref(&r->ref);

 			respond(r, err);

 			qunlock(c);

 			exits(nil);

 		case -1:

 			respond(r, "failed to init ride");

+			c->pid = 0;

+			c->req = nil;

+			decref(&r->ref);

+			qunlock(c);

 			break;

 		default:

-			c->pid = pid;

-			c->req = r;

 			return;

 		}

 		break;

@@ -490,7 +491,7 @@

 	Rfid *f;

 	Client *c;

 	char *buf, *err;

-	int pid, n, off;

+	int n, off;

 	buf = err = nil;

 	f = r->fid->aux;

@@ -502,11 +503,12 @@

 	case Qclient: dirread9p(r, genqclient, (void*)f->client); break;

 	case Qctl: buf = estrdup(c->qctl); break;

 	case Qinfo: buf = estrdup(c->qinfo); break;

-	case Qio:

-		switch(pid = rfork(RFPROC|RFNOWAIT|RFMEM)){

+	case Qdata:

+		qlock(c);

+		incref(&r->ref);

+		c->req = r;

+		switch(c->pid = rfork(RFPROC|RFNOWAIT|RFMEM)){

 		case 0:

-			qlock(c);

-

 			off = r->ifcall.offset - c->roff;

 			if(c->rn < 0){

 				free(c->r);

@@ -525,18 +527,20 @@

 				r->ofcall.count = n;

 			}

-			respond(r, err);

 			c->pid = 0;

 			c->req = nil;

-

+			decref(&r->ref);

+			respond(r, err);

 			qunlock(c);

 			exits(nil);

 		case -1:

 			err = "failed to fork read";

+			c->pid = 0;

+			c->req = nil;

+			decref(&r->ref);

+			qunlock(c);

 			break;

 		default:

-			c->pid = pid;

-			c->req = r;

 			return;

 		}

 		break;

@@ -554,7 +558,6 @@

 fswrite(Req *r){

 	Rfid *f;

 	Client *c;

-	int pid;

 	char *d, *err;

 	long n;

@@ -571,24 +574,29 @@

 	case Qctl:

 		r->ofcall.count = writeqctl(d, n, f->client);

 		break;

-	case Qio:

-		switch(pid = rfork(RFPROC|RFNOWAIT|RFMEM)){

+	case Qdata:

+		qlock(c);

+		incref(&r->ref);

+		c->req = r;

+		switch(c->pid = rfork(RFPROC|RFNOWAIT|RFMEM)){

 		case 0:

-			qlock(c);

 			r->ofcall.count = writemsg(c->fd, d, n);

-			respond(r, nil);

 			c->pid = 0;

 			c->req = nil;

+			decref(&r->ref);

+			respond(r, nil);

 			qunlock(c);

 			exits(nil);

 		case -1:

 			err = "failed to fork write";

+			c->pid = 0;

+			c->req = nil;

+			decref(&r->ref);

+			qunlock(c);

 			break;

 		default:

-			c->pid = pid;

-			c->req = r;

 			return;

 		}

 		break;

@@ -613,6 +621,7 @@

 		respond(c->req, "interrupted");

 		c->pid = 0;

 		c->req = nil;

+		decref(&c->req->ref);

 		qunlock(c);

 	}

--- a/test

+++ b/test

@@ -57,7 +57,7 @@

 	echo 'connect 192.168.11.17' >ctl ||

 		fail 'Could not connect to server'

-	<>io >[1=0] {

+	<>data >[1=0] {

 		~ `{wc -c info} 0 &&

 			fail 'Did not receive RIDE info'

@@ -78,12 +78,12 @@

 	cd `{read}

 	echo 'connect 192.168.11.17' >ctl

-	<>io >[1=0] {

+	<>data >[1=0] {

 		msg='["Execute",{"text":"⍳5\n","trace":0}]'

 		echo -n $msg || fail 'Could not send message'

 	} & spid=$apid

-	<>io >[1=0] {

+	<>data >[1=0] {

 		cat >/dev/null || fail 'Could not receive message'

 	} & rpid=$apid

-- 

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