libports: Create a notify_port in each bucket

This notify port will be used to request & receive Mach notifications.
While it is present in the bucket much like any other port, it is not
counted in ports_count_bucket () and is not exposed to the user
callback in ports_bucket_iterate ().

4 files changed, 45 insertions, 7 deletions

diff --git a/libports/bucket-iterate.c b/libports/bucket-iterate.c
index b021b99e..9103c297 100644
--- a/libports/bucket-iterate.c
+++ b/libports/bucket-iterate.c
@@ -1,5 +1,5 @@
 /* Iterate a function over the ports in a bucket.
-   Copyright (C) 1995, 1999 Free Software Foundation, Inc.
+   Copyright (C) 1995, 1999, 2021 Free Software Foundation, Inc.
    Written by Michael I. Bushnell.
 
    This file is part of the GNU Hurd.
@@ -76,7 +76,8 @@ _ports_bucket_class_iterate (struct hurd_ihash *ht,
   err = 0;
   for (i = 0; i < n; i++)
     {
-      if (!err)
+      /* Never expose the notify port to the user function.  */
+      if (!err && !ports_port_is_notify (p[i]))
 	err = (*fun)(p[i]);
       ports_port_deref (p[i]);
     }
diff --git a/libports/count-bucket.c b/libports/count-bucket.c
index 63feb6be..45fc7bfa 100644
--- a/libports/count-bucket.c
+++ b/libports/count-bucket.c
@@ -1,5 +1,5 @@
-/* 
-   Copyright (C) 1995 Free Software Foundation, Inc.
+/*
+   Copyright (C) 1995, 2021 Free Software Foundation, Inc.
    Written by Michael I. Bushnell.
 
    This file is part of the GNU Hurd.
@@ -24,11 +24,12 @@ int
 ports_count_bucket (struct port_bucket *bucket)
 {
   int ret;
-  
+
   pthread_mutex_lock (&_ports_lock);
-  ret = bucket->count;
+  /* Account for the notify port.  */
+  ret = bucket->count - 1;
   bucket->flags |= PORT_BUCKET_NO_ALLOC;
   pthread_mutex_unlock (&_ports_lock);
-  
+
   return ret;
 }
diff --git a/libports/create-bucket.c b/libports/create-bucket.c
index 82c00a4b..81fe044c 100644
--- a/libports/create-bucket.c
+++ b/libports/create-bucket.c
@@ -24,6 +24,15 @@
 #include <stdlib.h>
 #include <hurd/ihash.h>
 
+static struct port_class *notify_port_class;
+static pthread_once_t init_notify_port_class_once = PTHREAD_ONCE_INIT;
+
+static void
+init_notify_port_class ()
+{
+  notify_port_class = ports_create_class (NULL, NULL);
+}
+
 struct port_bucket *
 ports_create_bucket ()
 {
@@ -49,5 +58,19 @@ ports_create_bucket ()
   hurd_ihash_init (&ret->htable, offsetof (struct port_info, hentry));
   ret->rpcs = ret->flags = ret->count = 0;
   _ports_threadpool_init (&ret->threadpool);
+
+  /* Create the notify_port for this bucket.  */
+  pthread_once (&init_notify_port_class_once, init_notify_port_class);
+  err = ports_create_port (notify_port_class, ret,
+                           sizeof (struct port_info),
+                           &ret->notify_port);
+  if (err)
+    {
+      hurd_ihash_destroy (&ret->htable);
+      free (ret);
+      errno = err;
+      return NULL;
+    }
+
   return ret;
 }
diff --git a/libports/ports.h b/libports/ports.h
index 7295093d..f8ce9b6c 100644
--- a/libports/ports.h
+++ b/libports/ports.h
@@ -80,6 +80,8 @@ struct port_bucket
   int flags;
   int count;
   struct ports_threadpool threadpool;
+  /* A port in this bucket used to receive Mach notifications.  */
+  struct port_info *notify_port;
 };
 /* FLAGS above are the following: */
 #define PORT_BUCKET_INHIBITED	PORTS_INHIBITED
@@ -309,6 +311,17 @@ void ports_port_deref (void *port);
 /* Drop a weak reference to PORT. */
 void ports_port_deref_weak (void *port);
 
+/* Use this port right to request notifications about PORT. */
+#define ports_port_notify_right(port) \
+  ((struct port_info *) (port))->bucket->notify_port->port_right
+
+/* Is PORT the notify port for its bucket? */
+#define ports_port_is_notify(port)                  \
+  ({                                                \
+    struct port_info *__pi = (port);                \
+    __pi ? (__pi->bucket->notify_port == __pi) : 0; \
+  })
+
 /* The user is responsible for listening for no senders notifications;
    when one arrives, call this routine for the PORT the message was
    sent to, providing the MSCOUNT from the notification. */