[banshee] osx: avoid possible NREs when firing device events

[Andrés Aragoneses <aaragoneses src gnome org>]

commit 7513dcdd9c62aeb64a781127d1cf1a3225fa4322
Author: Andrés G. Aragoneses <knocte gmail com>
Date:   Sun Jun 21 20:41:44 2015 +0200

    osx: avoid possible NREs when firing device events
    
    The launch of these events was not protected with null checks,
    something which could potentially lead to NullReferenceExceptions
    if there were no observers for this events.

 .../Banshee.OsxBackend/HardwareManager.cs          |   24 +++++++++++++++-----
 1 files changed, 18 insertions(+), 6 deletions(-)
---
diff --git a/src/Backends/Banshee.Osx/Banshee.OsxBackend/HardwareManager.cs 
b/src/Backends/Banshee.Osx/Banshee.OsxBackend/HardwareManager.cs
index 37af6db..0c10651 100644
--- a/src/Backends/Banshee.Osx/Banshee.OsxBackend/HardwareManager.cs
+++ b/src/Backends/Banshee.Osx/Banshee.OsxBackend/HardwareManager.cs
@@ -44,7 +44,7 @@ namespace Banshee.OsxBackend
     public sealed class HardwareManager : IHardwareManager, IService
     {
         public event DeviceAddedHandler DeviceAdded;
-       public event DeviceChangedHandler DeviceChanged;
+        public event DeviceChangedHandler DeviceChanged;
         public event DeviceRemovedHandler DeviceRemoved;
 
         private List<IDevice> devices = new List<IDevice> ();
@@ -91,8 +91,11 @@ namespace Banshee.OsxBackend
                 if (new_device != null) {
                     devices.Add (new_device);
 
-                    // Notify that a device was added (i.e. to refresh device list)
-                    DeviceAdded (this, new DeviceAddedArgs ((IDevice) new_device));
+                    var added_handler = DeviceAdded;
+                    if (added_handler != null) {
+                        // Notify that a device was added (i.e. to refresh device list)
+                        added_handler (this, new DeviceAddedArgs ((IDevice)new_device));
+                    }
                 }
             }
         }
@@ -110,7 +113,10 @@ namespace Banshee.OsxBackend
                     // a device that was currently attached has changed 
                     // remove the device and immediately re-add it
                     devices.Remove (old_device);
-                    DeviceRemoved (old_device, new DeviceRemovedArgs (old_device.Uuid));
+                    var remove_handler = DeviceRemoved;
+                    if (remove_handler != null) {
+                        remove_handler (old_device, new DeviceRemovedArgs (old_device.Uuid));
+                    }
                 }
 
                 // do not add device without a VolumePath (=MountPoint)
@@ -126,7 +132,10 @@ namespace Banshee.OsxBackend
                     new_device = new Volume (args);
                 }
                 devices.Add (new_device);
-                DeviceAdded (this, new DeviceAddedArgs ((IDevice) new_device));
+                var added_handler = DeviceAdded;
+                if (added_handler != null) {
+                    added_handler (this, new DeviceAddedArgs ((IDevice)new_device));
+                }
             }
         }
 
@@ -141,7 +150,10 @@ namespace Banshee.OsxBackend
                 var old_device = devices.Where (d => d.Uuid == device.Uuid).FirstOrDefault ();
                 if (old_device != null) {
                     devices.Remove (old_device);
-                    DeviceRemoved (this, new DeviceRemovedArgs (old_device.Uuid));
+                    var removed_handler = DeviceRemoved;
+                    if (removed_handler != null) {
+                        removed_handler (this, new DeviceRemovedArgs (old_device.Uuid));
+                    }
                 }
             }
         }