Added support for reading the list of folder/file exclusion from the Windows registry

Duplicati/Library/Utility/DefaultFilters.cs

@@ -178,7 +178,7 @@ namespace Duplicati.Library.Utility
         /// <returns>Windows filters</returns>
         private static string[] CreateWindowsFilters()
         {
-            return new[]
+            var filters = new[]
             {
                 DefaultFilters.CreateWildcardFilter(@"*.rbf"),
                 DefaultFilters.CreateWildcardFilter(@"*.tmp"),
@@ -233,6 +233,12 @@ namespace Duplicati.Library.Utility
                 DefaultFilters.CreateWildcardFilter(@"?:/Windows/Installer*"),
                 DefaultFilters.CreateWildcardFilter(@"?:/Windows/Temp*"),
             };
+
+            var extra = GetWindowsRegistryFilters();
+            if (extra == null || extra.Length == 0)
+                return filters;
+
+            return filters.Union(extra).ToArray();
         }
 
         /// <summary>
@@ -368,5 +374,62 @@ namespace Duplicati.Library.Utility
             string escaped = System.Text.RegularExpressions.Regex.Escape(System.IO.Path.DirectorySeparatorChar.ToString());
             return "[" + filter.Replace(escapedAlt, escaped) + "]";
         }
+
+        /// <summary>
+        /// Wrapper method for getting a list of exclude paths from the Windows registry.
+        /// This method guards the call to <see cref="GetWindowsRegistryFiltersInternal"/> to avoid loader errors.
+        /// </summary>
+        /// <returns>The list of paths to exclude.</returns>
+        private static string[] GetWindowsRegistryFilters()
+        {
+            try
+            {
+                return GetWindowsRegistryFiltersInternal();
+            }
+            catch
+            {
+            }
+
+            return new string[0];
+        }
+
+        /// <summary>
+        /// Helper method that reads the Windows registry and finds paths to exclude.
+        /// This method should not be called directly as that could cause loader errors on Mono.
+        /// </summary>
+        /// <returns>The list of paths to exclude.</returns>
+        [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.NoInlining)]
+        private static string[] GetWindowsRegistryFiltersInternal()
+        {
+            var rk = Microsoft.Win32.RegistryKey.OpenBaseKey(Microsoft.Win32.RegistryHive.LocalMachine, Microsoft.Win32.RegistryView.Default);
+            if (rk == null)
+                return new string[0];
+
+            var sk = rk.OpenSubKey(@"SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToBackup");
+            if (sk == null)
+                return new string[0];
+
+            // Each value in this key is a potential path
+            return sk.GetValueNames()
+                 .Where(x => x != null)
+                 .SelectMany(x =>
+                 {
+                     var v = sk.GetValue(x);
+                     if (v is string)
+                         return new string[] { (string)v };
+                     else if (v is string[])
+                         return (string[])v;
+                     else
+                         return new string[0];
+                 })
+                 .Where(x => !string.IsNullOrWhiteSpace(x))
+                 .Select(x => Environment.ExpandEnvironmentVariables(x))
+                 .Where(x => !string.IsNullOrWhiteSpace(x))
+                 .Where(x => x.IndexOfAny(System.IO.Path.GetInvalidPathChars()) < 0)
+                 .Where(x => System.IO.Path.IsPathRooted(x))
+                 .Select(x => x.EndsWith(" /s", StringComparison.OrdinalIgnoreCase) ? x.Substring(0, x.Length - 3).TrimEnd() : x)
+                 .ToArray();
+        }
+
     }
 }