From 2995011b344808a8fb6fb7aef1706ab2890da0e4 Mon Sep 17 00:00:00 2001
From: Christian Helmuth <christian.helmuth@genode-labs.com>
Date: Thu, 15 Nov 2012 12:53:32 +0100
Subject: [PATCH] base-linux: implement IPC server destruction

When an IPC server is finalized two important things should happen:
First, the association of the server socket with a capability must be
invalidated. And finally, the server socket pair (server side and client
side) must be closed.

Related to #38.
---
 base-linux/src/base/env/platform_env.cc |  9 +++++
 base-linux/src/base/ipc/ipc.cc          | 51 +++++++++++++++++--------
 base-linux/src/core/platform.cc         | 11 ++++++
 3 files changed, 56 insertions(+), 15 deletions(-)

diff --git a/base-linux/src/base/env/platform_env.cc b/base-linux/src/base/env/platform_env.cc
index dc050de514..3b4c890d4a 100644
--- a/base-linux/src/base/env/platform_env.cc
+++ b/base-linux/src/base/env/platform_env.cc
@@ -14,9 +14,11 @@
 #include <util/arg_string.h>
 #include <base/platform_env.h>
 #include <base/thread.h>
+#include <linux_syscalls.h>
 
 using namespace Genode;
 
+
 /********************************
  ** Platform_env::Local_parent **
  ********************************/
@@ -124,4 +126,11 @@ namespace Genode {
 		}
 		return ncs;
 	}
+
+	void destroy_server_socket_pair(Native_connection_state const &ncs)
+	{
+		/* close local file descriptor if it is valid */
+		if (ncs.server_sd != -1) lx_close(ncs.server_sd);
+		if (ncs.client_sd != -1) lx_close(ncs.client_sd);
+	}
 }
diff --git a/base-linux/src/base/ipc/ipc.cc b/base-linux/src/base/ipc/ipc.cc
index 6b7b06d049..a3fff32402 100644
--- a/base-linux/src/base/ipc/ipc.cc
+++ b/base-linux/src/base/ipc/ipc.cc
@@ -46,6 +46,28 @@
 using namespace Genode;
 
 
+namespace Genode {
+
+	/*
+	 * Helper for obtaining a bound and connected socket pair
+	 *
+	 * For core, the implementation is just a wrapper around
+	 * 'lx_server_socket_pair()'. For all other processes, the implementation
+	 * requests the socket pair from the Env::CPU session interface using a
+	 * Linux-specific interface extension.
+	 */
+	Native_connection_state server_socket_pair();
+
+	/*
+	 * Helper to destroy the server socket pair
+	 *
+	 * For core, this is a no-op. For all other processes, the server and client
+	 * sockets are closed.
+	 */
+	void destroy_server_socket_pair(Native_connection_state const &ncs);
+}
+
+
 /******************************
  ** File-descriptor registry **
  ******************************/
@@ -390,7 +412,20 @@ Ipc_istream::Ipc_istream(Msgbuf_base *rcv_msg)
 { }
 
 
-Ipc_istream::~Ipc_istream() { }
+Ipc_istream::~Ipc_istream()
+{
+	/*
+	 * The association of the capability (client) socket must be invalidated on
+	 * server destruction. We implement it here as the IPC server currently has
+	 * no destructor. We have the plan to remove Ipc_istream and Ipc_ostream
+	 * in the future and, then, move this into the server destructor.
+	 *
+	 * IPC clients have -1 as client_sd and need no disassociation.
+	 */
+	if (_rcv_cs.client_sd != -1)
+		Genode::ep_sd_registry()->disassociate(_rcv_cs.client_sd);
+	destroy_server_socket_pair(_rcv_cs);
+}
 
 
 /****************
@@ -503,20 +538,6 @@ void Ipc_server::_reply_wait()
 }
 
 
-namespace Genode {
-
-	/*
-	 * Helper for obtaining a bound and connected socket pair
-	 *
-	 * For core, the implementation is just a wrapper around
-	 * 'lx_server_socket_pair()'. For all other processes, the implementation
-	 * requests the socket pair from the Env::CPU session interface using a
-	 * Linux-specific interface extension.
-	 */
-	Native_connection_state server_socket_pair();
-}
-
-
 Ipc_server::Ipc_server(Msgbuf_base *snd_msg, Msgbuf_base *rcv_msg)
 :
 	Ipc_istream(rcv_msg),
diff --git a/base-linux/src/core/platform.cc b/base-linux/src/core/platform.cc
index 5b003c4ef7..dfb1ff13fc 100644
--- a/base-linux/src/core/platform.cc
+++ b/base-linux/src/core/platform.cc
@@ -73,5 +73,16 @@ namespace Genode {
 	{
 		return create_server_socket_pair(Thread_base::myself()->tid().tid);
 	}
+
+	void destroy_server_socket_pair(Native_connection_state const &ncs)
+	{
+		/*
+		 * As entrypoints in core are never destructed, this function is only
+		 * called on IPC-client destruction. In this case, it's a no-op in core
+		 * as well as in Genode processes.
+		 */
+		if (ncs.server_sd != -1 || ncs.client_sd != -1)
+			PERR("%s called for IPC server which should never happen", __func__);
+	}
 }