Added proxy nodes in the dynamic translator stack

When setting dynamic translators, nsmux used to offer the client
a port to the dynamic translator directly. Now it gives off a
proxy node, which contains a port to the translator. Also, proxy
nodes are now included in dynamic translator stacks. Dynamic
translator stacks now consist of the following interconnected
conceptual blocks:

  -- shadow node -- translator -- proxy node --

3 files changed, 128 insertions, 33 deletions

diff --git a/node.c b/node.c
index f7db74107..1c47d735c 100644
--- a/node.c
+++ b/node.c
@@ -232,19 +232,23 @@ void node_destroy (node_t * np)
   /*TODO: If this node is a shadow node, kill the translator sitting
     on this node. */
 
-  /*Lock the lnode corresponding to the current node */
-  mutex_lock (&np->nn->lnode->lock);
+  /*If there is an lnode associated with the current node, detach
+    it */
+  if (np->nn->lnode)
+    {
+      if (np->nn->lnode->node == np)
+	{
+	  mutex_lock (&np->nn->lnode->lock);
 
-  /*If the node to be destroyed is a real netfs node */
-  if (np->nn->lnode->node == np)
-    /*orphan the light node */
-    np->nn->lnode->node = NULL;
-  else
-    /*remove a reference to this node from the list of proxies */
-    lnode_remove_proxy (np->nn->lnode, np);
+	  /*orphan the light node */
+	  np->nn->lnode->node = NULL;
 
-  /*Remove a reference from the lnode */
-  lnode_ref_remove (np->nn->lnode);
+	  lnode_ref_remove (np->nn->lnode);
+	}
+      else
+	/*remove a reference to this node from the list of proxies */
+	lnode_remove_proxy (np->nn->lnode, np);
+    }
 
   /*Free the netnode and the node itself */
   free (np->nn);
@@ -919,3 +923,72 @@ error_t
 }				/*node_set_translator */
 
 /*---------------------------------------------------------------------------*/
+/*Gets the port to the supplied node. */
+error_t
+  node_get_port
+  (struct protid * diruser, node_t * np, int flags, mach_port_t * port)
+{
+  error_t error = 0;
+
+  /*The new user for the port */
+  struct iouser * user;
+
+  /*The protid for the port */
+  struct protid * newpi;
+
+  /*Create a port to the supplied node without checking anything. */
+
+  flags &= ~OPENONLY_STATE_MODES;
+  error = iohelp_dup_iouser (&user, diruser->user);
+  if (error)
+    return error;
+
+  newpi = netfs_make_protid 
+    (netfs_make_peropen (np, flags, diruser->po), user);
+  if (!newpi)
+    {
+      iohelp_free_iouser (user);
+      error = errno;
+      return error;
+    }
+  
+  *port = ports_get_right (newpi);
+  ports_port_deref (newpi);
+  return error;
+}				/*node_get_port */
+
+/*---------------------------------------------------------------------------*/
+/*Gets the send port right to the supplied node. */
+error_t
+  node_get_send_port
+  (struct protid * diruser, node_t * np, int flags, mach_port_t * port)
+{
+  error_t error = 0;
+
+  /*The new user for the port */
+  struct iouser * user;
+
+  /*The protid for the port */
+  struct protid * newpi;
+
+  /*Create a port to the supplied node without checking anything. */
+
+  flags &= ~OPENONLY_STATE_MODES;
+  error = iohelp_dup_iouser (&user, diruser->user);
+  if (error)
+    return error;
+
+  newpi = netfs_make_protid 
+    (netfs_make_peropen (np, flags, diruser->po), user);
+  if (!newpi)
+    {
+      iohelp_free_iouser (user);
+      error = errno;
+      return error;
+    }
+  
+  *port = ports_get_send_right (newpi);
+  ports_port_deref (newpi);
+  return error;
+}				/*node_get_send_port */
+/*---------------------------------------------------------------------------*/
diff --git a/node.h b/node.h
index 9ae760f01..7cb154386 100644
--- a/node.h
+++ b/node.h
@@ -151,9 +151,19 @@ error_t node_unlink_file (node_t * dir, char *name);
 /*Starts translator `trans` on the (shadow) node `np`, which should
   mirror the file `filename`, and returns the port `port` to the root
   of the translator opened as `flags.`*/
-error_t 
+error_t
   node_set_translator
   (struct protid *diruser, node_t * np, char * trans, int flags,
    char * filename, mach_port_t * port);
 /*---------------------------------------------------------------------------*/
+/*Gets the port to the supplied node. */
+error_t
+  node_get_port
+  (struct protid * diruser, node_t * np, int flags, mach_port_t * port);
+/*---------------------------------------------------------------------------*/
+/*Gets the send port right to the supplied node. */
+error_t
+  node_get_send_port
+  (struct protid * diruser, node_t * np, int flags, mach_port_t * port);
+/*---------------------------------------------------------------------------*/
 #endif /*__NODE_H__*/
diff --git a/nsmux.c b/nsmux.c
index 0f713f14a..d2da05086 100644
--- a/nsmux.c
+++ b/nsmux.c
@@ -765,7 +765,7 @@ error_t
   struct protid *newpi;
   struct iouser *user;
 
-  /*The port to the file for the case when we don't need proxy nodes */
+  /*The port to the file */
   file_t file = MACH_PORT_NULL;
 
   /*The port to the same file with restricted rights */
@@ -905,6 +905,20 @@ error_t
 		  netfs_nref (np);
 
 		  mutex_unlock (&np->lock);
+
+		  /*`np` is a proxy node of the lower translator. We
+		    have to create a shadow node explicitly. */
+		  error = node_get_send_port (diruser, np, flags, &file);
+		  if (error)
+		    goto out;
+
+		  error = node_create_from_port(file, &np);
+		  if (error)
+		    goto out;
+
+		  /*`np` is supposed to be unlocked by the following
+		    code. */
+		  mutex_unlock (&np->lock);
 		}
 	      else
 		  /*lookup the file in the real filesystem */ 
@@ -914,7 +928,7 @@ error_t
 
 	      if (!error && !excl)
 		{
-		  /*if there is at least one more separator in the
+		  /*If there is at least one more separator in the
 		    filename, we will have to do a retry */
 		  nextsep = magic_find_sep(sep);
 		  if (nextsep)
@@ -925,7 +939,7 @@ error_t
 			goto out;
 		      strncpy(trans, sep, trans_len);
 		      trans[trans_len] = 0;
-
+		      
 		      /*set the required translator on the node */
 		      error = node_set_translator
 			(diruser, np, trans, flags, filename, &file);
@@ -947,28 +961,15 @@ error_t
 		      netfs_nput (np);
 		      error = node_create_from_port (file, &np);
 
+		      /*create a port to the proxy node */
+
 		      /*we don't check the permissions here, because
 			this check has been performed in the lookup of
-			the real filename in the beginning of the
+			the real filename at the beginning of the
 			process of setting up the dynamic translator
 			stack */
 
-		      flags &= ~OPENONLY_STATE_MODES;
-		      error = iohelp_dup_iouser (&user, diruser->user);
-		      if (error)
-			goto out;
-
-		      newpi = netfs_make_protid 
-			(netfs_make_peropen (np, flags, diruser->po), user);
-		      if (!newpi)
-			{
-			  iohelp_free_iouser (user);
-			  error = errno;
-			  goto out;
-			}
-
-		      *retry_port = ports_get_right (newpi);
-		      ports_port_deref (newpi);
+		      error = node_get_port (diruser, np, flags, retry_port);
 
 		      if (np)
 			netfs_nput (np);
@@ -985,10 +986,21 @@ error_t
 		  if (error)
 		    goto out;
 
+		  /*create a proxy node for the port to the current
+		    translator */
+		  netfs_nput (np);
+		  error = node_create_from_port (file, &np);
+
+		  /*create a port to the proxy node */
+		  error = node_get_port (diruser, np, flags, retry_port);
+		  if (error)
+		    goto out;
+
   		  /*No more retries are necessary, if we are at the
 		    last component of the filename */
 		  if(lastcomp)
-		    goto justport;
+		    /*goto justport; */
+		    goto out;
 		  else
 		    /*TODO: Do a retry in case this is not the last
 		      component of the filename. */