[chronojump] Added IsFileLocked check to processes like webcam record

[Xavier de Blas <xaviblas src gnome org>]

commit 279ccb55d21f74fb20804dab32b0523c5776a3dd
Author: Xavier de Blas <xaviblas gmail com>
Date:   Fri Feb 8 15:48:04 2019 +0100

    Added IsFileLocked check to processes like webcam record

 src/executeProcess.cs | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
---
diff --git a/src/executeProcess.cs b/src/executeProcess.cs
index d051bf1c..6d690e1c 100644
--- a/src/executeProcess.cs
+++ b/src/executeProcess.cs
@@ -325,6 +325,30 @@ class ExecuteProcess
        }
        */
 
+       public static bool IsFileLocked(FileInfo finfo)
+       {
+               //https://stackoverflow.com/a/937558
+               FileStream stream = null;
+
+               try {
+                       stream = finfo.Open(FileMode.Open, FileAccess.Read, FileShare.None);
+               }
+               catch (IOException) {
+                       //the file is unavailable because it is:
+                       //still being written to
+                       //or being processed by another thread
+                       //or does not exist (has already been processed)
+                       return true;
+               }
+               finally {
+                       if (stream != null)
+                               stream.Close();
+               }
+
+               //file is not locked
+               return false;
+       }
+
        /*
         * The process.Responding only works on GUI processes
         * So, here we send a "ping" expecting to see the result in short time