plugin/explorer: ensure env var paths are absolute

Author: JohnTheGr8

Plugins/Flow.Launcher.Plugin.Explorer/Search/EnvironmentVariables.cs

@@ -22,11 +22,18 @@ internal static Dictionary<string, string> LoadEnvironmentStringPaths()
 
             foreach (DictionaryEntry special in Environment.GetEnvironmentVariables())
             {
-                if (Directory.Exists(special.Value.ToString()))
+                var path = special.Value.ToString();
+                if (Directory.Exists(path))
                 {
+                    // we add a trailing slash to the path to make sure drive paths become valid absolute paths.
+                    // for example, if %systemdrive% is C: we turn it to C:\
+                    path = path.TrimEnd(Path.DirectorySeparatorChar) + Path.DirectorySeparatorChar;
+                    // if we don't have an absolute path, we use Path.GetFullPath to get one.
+                    // for example, if %homepath% is \Users\John we turn it to C:\Users\John
+                    path = Path.IsPathFullyQualified(path) ? path : Path.GetFullPath(path);
                     // Variables are returned with a mixture of all upper/lower case. 
                     // Call ToLower() to make the results look consistent
-                    envStringPaths.Add(special.Key.ToString().ToLower(), special.Value.ToString());
+                    envStringPaths.Add(special.Key.ToString().ToLower(), path);
                 }
             }