(fshelp_fetch_root): Reduce levels of loops. Only change ACTIVE when

we are holding the lock.  Use condition mechanism to serialize
attempts to start the passive translator.

1 files changed, 106 insertions, 95 deletions

diff --git a/libfshelp/fetch-root.c b/libfshelp/fetch-root.c
index d69493ba..327bbe35 100644
--- a/libfshelp/fetch-root.c
+++ b/libfshelp/fetch-root.c
@@ -36,113 +36,124 @@ fshelp_fetch_root (struct transbox *box, void *cookie,
   error_t err;
   mach_port_t control;
   
-  do
+ start_over:
+
+  if (box->active != MACH_PORT_NULL)
+    assert (box->flags & TRANSBOX_STARTING == 0);
+  else
     {
-      if (box->active == MACH_PORT_NULL)
-	do
+      mach_port_t underlying;
+      uid_t uid, gid;
+      char *argz;
+      int argz_len;
+      error_t err;
+      mach_port_t ports[INIT_PORT_MAX];
+      int ints[INIT_INT_MAX];
+      mach_port_t fds[STDERR_FILENO + 1];
+      auth_t ourauth, newauth;
+      int uidarray[2], gidarray[2];
+      
+      mach_port_t
+	reauth (mach_port_t port)
 	  {
-	    mach_port_t underlying;
-	    uid_t uid, gid;
-	    char *argz;
-	    int argz_len;
+	    mach_port_t rend, ret;
 	    error_t err;
-	    mach_port_t ports[INIT_PORT_MAX];
-	    int ints[INIT_INT_MAX];
-	    mach_port_t fds[STDERR_FILENO + 1];
-	    auth_t ourauth, newauth;
-	    int uidarray[2], gidarray[2];
-      
-	    mach_port_t
-	      reauth (mach_port_t port)
-		{
-		  mach_port_t rend, ret;
-		  error_t err;
 
-		  rend = mach_reply_port ();
-		  err = io_reauthenticate (port, rend, 
-					   MACH_MSG_TYPE_MAKE_SEND);
-		  assert_perror (err);
-
-		  err = auth_user_authenticate (newauth, port, rend,
-						MACH_MSG_TYPE_MAKE_SEND,
-						&ret);
-		  if (err)
-		    ret = MACH_PORT_NULL;
-	  
-		  mach_port_destroy (mach_task_self (), rend);
-		  mach_port_deallocate (mach_task_self (), port);
-		  return ret;
-		}
-
-	    err = (*callback) (box->cookie, cookie, &underlying, &uid,
-			       &gid, &argz, &argz_len);
-	    if (err)
-	      return err;
-	          
-	    mutex_lock (&box->innerlock); /* cancellation point XXX */
-	    mutex_unlock (box->lock);
-
-	    ourauth = getauth ();
-	    uidarray[0] = uidarray[1] = uid;
-	    gidarray[0] = gidarray[1] = gid;
-	    err = auth_makeauth (ourauth, MACH_PORT_NULL, 0, 
-				 MACH_MSG_TYPE_MAKE_SEND,
-				 uidarray, 1, uidarray, 2,
-				 gidarray, 1, gidarray, 2, &newauth);
+	    rend = mach_reply_port ();
+	    err = io_reauthenticate (port, rend, 
+				     MACH_MSG_TYPE_MAKE_SEND);
 	    assert_perror (err);
-      
-	    bzero (ports, INIT_PORT_MAX * sizeof (mach_port_t));
-	    bzero (fds, (STDERR_FILENO + 1) * sizeof (mach_port_t));
-	    bzero (ints, INIT_INT_MAX * sizeof (int));
-
-	    ports[INIT_PORT_CWDIR] = reauth (getcwdir ());
-	    ports[INIT_PORT_CRDIR] = reauth (getcrdir ());
-	    ports[INIT_PORT_AUTH] = newauth;
- 
-	    fds[STDERR_FILENO] = reauth (getdport (STDERR_FILENO));
-      
-	    err = fshelp_start_translator_long (reauth (underlying),
-						MACH_MSG_TYPE_MOVE_SEND,
-						argz, argz, argz_len,
-						fds, STDERR_FILENO + 1,
-						MACH_MSG_TYPE_MOVE_SEND,
-						ports, INIT_PORT_MAX, 
-						MACH_MSG_TYPE_MOVE_SEND,
-						ints, INIT_INT_MAX,
-						0, &box->active);
-	    mutex_unlock (&box->innerlock);
-      
-	    free (argz);
 
+	    err = auth_user_authenticate (newauth, port, rend,
+					  MACH_MSG_TYPE_MAKE_SEND,
+					  &ret);
 	    if (err)
-	      return err;
-
-	    mutex_lock (box->lock);
-	
-	    /* The loop here is because between the interlock unlock and
-	       the reacquire of the node lock, someone might have deallocated
-	       the port we just added. */
+	      ret = MACH_PORT_NULL;
+	  
+	    mach_port_destroy (mach_task_self (), rend);
+	    mach_port_deallocate (mach_task_self (), port);
+	    return ret;
 	  }
-	while (box->active == MACH_PORT_NULL);
-
-      control = box->active;
-      mach_port_mod_refs (mach_task_self (), control, 
-			  MACH_PORT_RIGHT_SEND, 1);
+      
+      if (box->flags & TRANSBOX_STARTING)
+	{
+	  box->flags |= TRANSBOX_WANTED;
+	  condition_wait (&box->wakeup, box->lock);
+	  goto start_over;
+	}
+      box->flags |= TRANSBOX_STARTING;
       mutex_unlock (box->lock);
-
-      /* Cancellation point XXX */
-      err = fsys_getroot (control, dotdot, MACH_MSG_TYPE_COPY_SEND,
-			  uids, uids_len, gids, gids_len, flags,
-			  retry, retryname, root);
+	  
+      err = (*callback) (box->cookie, cookie, &underlying, &uid,
+			 &gid, &argz, &argz_len);
+      if (err)
+	return err;
+      
+      ourauth = getauth ();
+      uidarray[0] = uidarray[1] = uid;
+      gidarray[0] = gidarray[1] = gid;
+      err = auth_makeauth (ourauth, MACH_PORT_NULL, 0, 
+			   MACH_MSG_TYPE_MAKE_SEND,
+			   uidarray, 1, uidarray, 2,
+			   gidarray, 1, gidarray, 2, &newauth);
+      assert_perror (err);
+      
+      bzero (ports, INIT_PORT_MAX * sizeof (mach_port_t));
+      bzero (fds, (STDERR_FILENO + 1) * sizeof (mach_port_t));
+      bzero (ints, INIT_INT_MAX * sizeof (int));
+      
+      ports[INIT_PORT_CWDIR] = reauth (getcwdir ());
+      ports[INIT_PORT_CRDIR] = reauth (getcrdir ());
+      ports[INIT_PORT_AUTH] = newauth;
+      
+      fds[STDERR_FILENO] = reauth (getdport (STDERR_FILENO));
+      
+      err = fshelp_start_translator_long (reauth (underlying),
+					  MACH_MSG_TYPE_MOVE_SEND,
+					  argz, argz, argz_len,
+					  fds, STDERR_FILENO + 1,
+					  MACH_MSG_TYPE_MOVE_SEND,
+					  ports, INIT_PORT_MAX, 
+					  MACH_MSG_TYPE_MOVE_SEND,
+					  ints, INIT_INT_MAX,
+					  0, &control);
       
       mutex_lock (box->lock);
-
-      if ((err == MACH_SEND_INVALID_DEST || err == MIG_SERVER_DIED)
-	  && control == box->active)
-	fshelp_set_active (box, MACH_PORT_NULL);
-      mach_port_deallocate (mach_task_self (), control);
+      
+      free (argz);
+      
+      if (err)
+	return err;
+      
+      box->active = control;
+      
+      box->flags &= ~TRANSBOX_STARTING;
+      if (box->flags & TRANSBOX_WANTED)
+	{
+	  box->flags &= ~TRANSBOX_WANTED;
+	  condition_broadcast (&box->wakeup);
+	}
     }
-  while (err == MACH_SEND_INVALID_DEST || err == MIG_SERVER_DIED);
+  
+  control = box->active;
+  mach_port_mod_refs (mach_task_self (), control, 
+		      MACH_PORT_RIGHT_SEND, 1);
+  mutex_unlock (box->lock);
+  
+  /* Cancellation point XXX */
+  err = fsys_getroot (control, dotdot, MACH_MSG_TYPE_COPY_SEND,
+		      uids, uids_len, gids, gids_len, flags,
+		      retry, retryname, root);
+  
+  mutex_lock (box->lock);
+  
+  if ((err == MACH_SEND_INVALID_DEST || err == MIG_SERVER_DIED)
+      && control == box->active)
+    fshelp_set_active (box, MACH_PORT_NULL);
+  mach_port_deallocate (mach_task_self (), control);
+
+  if (err == MACH_SEND_INVALID_DEST || err == MIG_SERVER_DIED)
+    goto start_over;
   
   return err;
 }