[glibmm] DBus: Avoid errors/exceptions in callbacks due to NULL C strings.

[José Alburquerque <jaalburqu src gnome org>]

commit 7e694da5eea703de072192f47940bbedd3287650
Author: José Alburquerque <jaalburqu svn gnome org>
Date:   Thu Jan 13 17:00:31 2011 -0500

    DBus: Avoid errors/exceptions in callbacks due to NULL C strings.
    
    	* gio/src/dbusconnection.ccg: Modify the callbacks so that if a C
    	string parameter might be NULL, it is passed to the slots as an empty
    	string ("").  This avoids possible exceptions from constructing a
    	Glib::ustring from NULL.
    	* gio/src/dbusconnection.hg: Typos.
    
    	* examples/dbus/peer.cc: Add the usage examples from the C API's
    	example.

 ChangeLog                  |   13 ++++++++
 examples/dbus/peer.cc      |   72 ++++++++++++++++++++++++++++++++++++++++++--
 gio/src/dbusconnection.ccg |   33 ++++++++------------
 gio/src/dbusconnection.hg  |    8 ++--
 4 files changed, 99 insertions(+), 27 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index e2e2943..6eed6ef 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,18 @@
 2011-01-13  José Alburquerque  <jaalburqu svn gnome org>
 
+	DBus: Avoid errors/exceptions in callbacks due to NULL C strings.
+
+	* gio/src/dbusconnection.ccg: Modify the callbacks so that if a C
+	string parameter might be NULL, it is passed to the slots as an empty
+	string ("").  This avoids possible exceptions from constructing a
+	Glib::ustring from NULL.
+	* gio/src/dbusconnection.hg: Typos.
+
+	* examples/dbus/peer.cc: Add the usage examples from the C API's
+	example.
+
+2011-01-13  José Alburquerque  <jaalburqu svn gnome org>
+
 	DBusServer: Add docs to the signal_new_connection() signal.
 
 	* gio/src/dbusserver.hg: Add the docs from the C API to make sure it
diff --git a/examples/dbus/peer.cc b/examples/dbus/peer.cc
index 6d383c3..6bedafc 100644
--- a/examples/dbus/peer.cc
+++ b/examples/dbus/peer.cc
@@ -15,9 +15,75 @@
  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
-/* For some usage examples see the C API's GDBusServer's example from which
- * this example was adapted.
- */
+/*
+
+Usage examples (modulo addresses / credentials) (copied from the C API's
+GDBusServer's example).
+
+UNIX domain socket transport:
+
+ Server:
+   $ ./peer --server --address unix:abstract=myaddr
+   Server is listening at: unix:abstract=myaddr
+   Client connected.
+   Peer credentials: GCredentials:unix-user=500,unix-group=500,unix-process=13378
+   Negotiated capabilities: unix-fd-passing=1
+   Client said: Hey, it's 1273093080 already!
+
+ Client:
+   $ ./peer --address unix:abstract=myaddr
+   Connected.
+   Negotiated capabilities: unix-fd-passing=1
+   Server said: You said 'Hey, it's 1273093080 already!'. KTHXBYE!
+
+Nonce-secured TCP transport on the same host:
+
+ Server:
+   $ ./peer --server --address nonce-tcp:
+   Server is listening at: nonce-tcp:host=localhost,port=43077,noncefile=/tmp/gdbus-nonce-file-X1ZNCV
+   Client connected.
+   Peer credentials: (no credentials received)
+   Negotiated capabilities: unix-fd-passing=0
+   Client said: Hey, it's 1273093206 already!
+
+ Client:
+   $ ./peer -address nonce-tcp:host=localhost,port=43077,noncefile=/tmp/gdbus-nonce-file-X1ZNCV
+   Connected.
+   Negotiated capabilities: unix-fd-passing=0
+   Server said: You said 'Hey, it's 1273093206 already!'. KTHXBYE!
+
+TCP transport on two different hosts with a shared home directory:
+
+ Server:
+   host1 $ ./peer --server --address tcp:host=0.0.0.0
+   Server is listening at: tcp:host=0.0.0.0,port=46314
+   Client connected.
+   Peer credentials: (no credentials received)
+   Negotiated capabilities: unix-fd-passing=0
+   Client said: Hey, it's 1273093337 already!
+
+ Client:
+   host2 $ ./peer -a tcp:host=host1,port=46314
+   Connected.
+   Negotiated capabilities: unix-fd-passing=0
+   Server said: You said 'Hey, it's 1273093337 already!'. KTHXBYE!
+
+TCP transport on two different hosts without authentication:
+
+ Server:
+   host1 $ ./peer --server --address tcp:host=0.0.0.0 --allow-anonymous
+   Server is listening at: tcp:host=0.0.0.0,port=59556
+   Client connected.
+   Peer credentials: (no credentials received)
+   Negotiated capabilities: unix-fd-passing=0
+   Client said: Hey, it's 1273093652 already!
+
+ Client:
+   host2 $ ./peer -a tcp:host=host1,port=59556
+   Connected.
+   Negotiated capabilities: unix-fd-passing=0
+   Server said: You said 'Hey, it's 1273093652 already!'. KTHXBYE!
+*/
 
 #include <giomm.h>
 #include <glibmm.h>
diff --git a/gio/src/dbusconnection.ccg b/gio/src/dbusconnection.ccg
index a3b47ee..1347a56 100644
--- a/gio/src/dbusconnection.ccg
+++ b/gio/src/dbusconnection.ccg
@@ -40,9 +40,9 @@ static void DBusConnection_Signal_giomm_callback(GDBusConnection* connection,
 
   try
   {
-    (*the_slot)(Glib::wrap(connection, true), Glib::ustring(sender_name),
-      Glib::ustring(object_path), Glib::ustring(interface_name),
-      Glib::ustring(signal_name), Glib::VariantBase(parameters, true));
+    (*the_slot)(Glib::wrap(connection, true), (sender_name ? sender_name : ""),
+      (object_path ? object_path : ""), (interface_name ? interface_name : ""),
+      (signal_name ? signal_name : ""), Glib::VariantBase(parameters, true));
   }
   catch(...)
   {
@@ -95,11 +95,9 @@ static void DBusInterfaceVTable_MethodCall_giomm_callback(
 
   try
   {
-    (*the_slot)(Glib::wrap(connection, true),
-      (sender ? Glib::ustring(sender) : ""),
-      Glib::ustring(object_path), Glib::ustring(interface_name),
-      Glib::ustring(method_name), Glib::VariantBase(parameters, true),
-      Glib::wrap(invocation, true));
+    (*the_slot)(Glib::wrap(connection, true), (sender ? sender : ""),
+      object_path, interface_name, method_name,
+      Glib::VariantBase(parameters, true), Glib::wrap(invocation, true));
   }
   catch(...)
   {
@@ -122,9 +120,8 @@ static GVariant* DBusInterfaceVTable_GetProperty_giomm_callback(
   {
     Glib::VariantBase result;
 
-    (*the_slot)(result, Glib::wrap(connection, true),
-      Glib::ustring(sender), Glib::ustring(object_path),
-      Glib::ustring(interface_name), Glib::ustring(property_name));
+    (*the_slot)(result, Glib::wrap(connection, true), sender, object_path,
+      interface_name, property_name);
     return result.gobj_copy();
   }
   catch(const Glib::Error& ex)
@@ -154,8 +151,7 @@ static gboolean DBusInterfaceVTable_SetProperty_giomm_callback(
   try
   {
     return static_cast<gboolean>((*the_slot)(Glib::wrap(connection, true),
-      Glib::ustring(sender), Glib::ustring(object_path),
-      Glib::ustring(interface_name), Glib::ustring(property_name),
+      sender, object_path, interface_name, property_name,
       Glib::VariantBase(value, true)));
   }
   catch(const Glib::Error& ex)
@@ -184,8 +180,7 @@ static char** DBusSubtreeVTable_Enumerate_giomm_callback(
   try
   {
     std::vector<Glib::ustring> result =
-      (*the_slot)(Glib::wrap(connection, true), Glib::ustring(sender),
-      Glib::ustring(object_path));
+      (*the_slot)(Glib::wrap(connection, true), sender, object_path);
 
     // This will be freed by the caller.
     char** ret = g_new(char*, result.size());
@@ -218,8 +213,7 @@ static GDBusInterfaceInfo** DBusSubtreeVTable_Introspect_giomm_callback(
   try
   {
     std::vector< Glib::RefPtr<Gio::DBusInterfaceInfo> > result =
-      (*the_slot)(Glib::wrap(connection, true), Glib::ustring(sender),
-      Glib::ustring(object_path), Glib::ustring(node));
+      (*the_slot)(Glib::wrap(connection, true), sender, object_path, node);
 
     // This will be freed by the caller, along with unreferencing its members.
     GDBusInterfaceInfo** info = g_new(GDBusInterfaceInfo*, result.size());
@@ -255,9 +249,8 @@ static const GDBusInterfaceVTable* DBusSubtreeVTable_Dispatch_giomm_callback(
   try
   {
     const Gio::DBusInterfaceVTable* vtable =
-      (*the_slot)(Glib::wrap(connection, true), Glib::ustring(sender),
-      Glib::ustring(object_path), Glib::ustring(interface_name),
-      Glib::ustring(node));
+      (*the_slot)(Glib::wrap(connection, true), sender, object_path,
+      interface_name, (node ? node : ""));
 
     *out_user_data = const_cast<Gio::DBusInterfaceVTable*>(vtable);
 
diff --git a/gio/src/dbusconnection.hg b/gio/src/dbusconnection.hg
index a79784b..ba41ee2 100644
--- a/gio/src/dbusconnection.hg
+++ b/gio/src/dbusconnection.hg
@@ -157,7 +157,7 @@ public:
   /** Signature for slot used in signal_subscribe().
    *  For example,
    * @code
-   * void on_signal(const Glib::RefPtr<DBusConnection>&, const
+   * void on_signal(const Glib::RefPtr<DBusConnection>& connection, const
    * Glib::ustring& sender_name, const Glib::ustring& object_path, const
    * Glib::ustring& object_path, const Glib::ustring& interface_name, const
    * Glib::ustring& signal_name, const Glib::VariantBase& parameters);.
@@ -165,14 +165,14 @@ public:
    */
   typedef sigc::slot<void, const Glib::RefPtr<DBusConnection>&,
     const Glib::ustring&, const Glib::ustring&, const Glib::ustring&,
-    const Glib::ustring&, const Glib::VariantBase&>  SlotSignal;
+    const Glib::ustring&, const Glib::VariantBase&> SlotSignal;
 
   /** Signature for slot used in add_filter().
    *  For example,
    * @code
    * Glib::RefPtr<DBusMessage> on_message_filter(const
-   * Glib::RefPtr<DBusConnection>, const Glib::RefPtr<DBusMessage>& bool
-   * incoming);.
+   * Glib::RefPtr<DBusConnection> connection, const Glib::RefPtr<DBusMessage>&
+   * message, bool incoming);.
    * @endcode
    *
    * A filter function is passed a DBusMessage and expected to return a