libfshelp: fix the api of fshelp_set_active_translator

To detect if an active translator goes away, we need to register for
dead name notifications. Those notifications have to be sent to a port
known to the ports library, as the ports library handles the dead name
notifications. The most straight forward way is to use the port to the
underlying node for that. To that end, a reference to the port_info
struct is handed in and kept in the list of active translators.

This commit also moves the registration of dead name notifications to
libfshelp.

* libfshelp/fshelp.h (fshelp_set_active_translator): Add port_info argument.
* libfshelp/translator-list.c (struct translator): Add port_info pointer.
(translator_ihash_cleanup): Dereference port_info object.
(fshelp_set_active_translator): Register dead name notifications.
* libdiskfs/file-set-trans.c (diskfs_S_file_set_translator): Update
  accordingly.
* libnetfs/file-set-translator.c (netfs_S_file_set_translator): Likewise.

1 files changed, 36 insertions, 7 deletions

diff --git a/libfshelp/translator-list.c b/libfshelp/translator-list.c
index 87dcb211..3ece7112 100644
--- a/libfshelp/translator-list.c
+++ b/libfshelp/translator-list.c
@@ -1,6 +1,6 @@
 /* A list of active translators.
 
-   Copyright (C) 2013 Free Software Foundation, Inc.
+   Copyright (C) 2013,14 Free Software Foundation, Inc.
 
    Written by Justus Winter <4winter@informatik.uni-hamburg.de>
 
@@ -22,6 +22,7 @@
 #include <argz.h>
 #include <hurd/fsys.h>
 #include <hurd/ihash.h>
+#include <hurd/ports.h>
 #include <mach.h>
 #include <mach/notify.h>
 #include <pthread.h>
@@ -33,6 +34,7 @@
 
 struct translator
 {
+  struct port_info *pi;
   char *name;
   mach_port_t active;
 };
@@ -49,8 +51,10 @@ translator_ihash_cleanup (void *element, void *arg)
 {
   struct translator *translator = element;
 
-  /* No need to deallocate port, we only keep the name of the
-     port, not a reference.  */
+  if (translator->pi)
+    ports_port_deref (translator->pi);
+  /* No need to deallocate translator->active, we only keep the name of
+     the port, not a reference.  */
   free (translator->name);
   free (translator);
 }
@@ -58,7 +62,9 @@ translator_ihash_cleanup (void *element, void *arg)
 /* Record an active translator being bound to the given file name
    NAME.  ACTIVE is the control port of the translator.  */
 error_t
-fshelp_set_active_translator (const char *name, mach_port_t active)
+fshelp_set_active_translator (struct port_info *pi,
+			      const char *name,
+			      mach_port_t active)
 {
   error_t err = 0;
   pthread_mutex_lock (&translator_ihash_lock);
@@ -79,6 +85,7 @@ fshelp_set_active_translator (const char *name, mach_port_t active)
     return ENOMEM;
 
   t->active = MACH_PORT_NULL;
+  t->pi = NULL;
   t->name = strdup (name);
   if (! t->name)
     {
@@ -93,9 +100,31 @@ fshelp_set_active_translator (const char *name, mach_port_t active)
 
  update:
   if (active)
-    /* No need to increment the reference count, we only keep the
-       name, not a reference.  */
-    t->active = active;
+    {
+      if (t->pi != pi)
+	{
+	  mach_port_t old;
+	  err = mach_port_request_notification (mach_task_self (), active,
+						MACH_NOTIFY_DEAD_NAME, 0,
+						pi->port_right,
+						MACH_MSG_TYPE_MAKE_SEND_ONCE,
+						&old);
+	  if (err)
+	    return err;
+	  if (old != MACH_PORT_NULL)
+	    mach_port_deallocate (mach_task_self (), old);
+
+	  if (t->pi)
+	    ports_port_deref (t->pi);
+
+	  ports_port_ref (pi);
+	  t->pi = pi;
+	}
+
+      /* No need to increment the reference count, we only keep the
+	 name, not a reference.  */
+      t->active = active;
+    }
   else
     hurd_ihash_remove (&translator_ihash, (hurd_ihash_key_t) t);