[at-spi2-core] Fix crash if GetChildAtIndex is called with an invalid index

[Mike Gorse <mgorse src gnome org>]

commit db7aeabe87378e343c9e1fff5503b4f1d239ad6d
Author: Mike Gorse <mgorse novell com>
Date:   Mon May 31 12:24:58 2010 -0400

    Fix crash if GetChildAtIndex is called with an invalid index

 registryd/registry.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/registryd/registry.c b/registryd/registry.c
index f3728f8..8391971 100644
--- a/registryd/registry.c
+++ b/registryd/registry.c
@@ -494,8 +494,13 @@ impl_GetChildAtIndex (DBusConnection * bus,
   reply = dbus_message_new_method_return (message);
   dbus_message_iter_init_append (reply, &iter);
 
-  ref = g_ptr_array_index (reg->apps, i);
-  append_reference (&iter, ref->name, ref->path);
+  if (i < 0 || i >= reg->apps->len)
+    append_reference (&iter, SPI_DBUS_NAME_REGISTRY, SPI_DBUS_PATH_NULL);
+  else
+    {
+      ref = g_ptr_array_index (reg->apps, i);
+      append_reference (&iter, ref->name, ref->path);
+    }
 
   return reply;
 }