Added .NET 4.6.1 target

* adds Pollyfil for System.Runtime.InteropServices.RuntimeInformation
* fixes #1605

Author: devlead

Directory.Build.props

@@ -7,4 +7,8 @@
     <DefineConstants Condition=" '$(ExtraDefine)' != '' ">$(DefineConstants);$(ExtraDefine)</DefineConstants>
   </PropertyGroup>
 
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
+    <DefineConstants>$(DefineConstants);NETCORE</DefineConstants>
+  </PropertyGroup>
+
 </Project>

LibGit2Sharp.Tests/LibGit2Sharp.Tests.csproj

@@ -29,7 +29,6 @@
   <Target Name="CopyTestAppExes" AfterTargets="ResolveProjectReferences">
     <ItemGroup>
       <_TestAppFile Include="@(TestAppExe->'%(RootDir)%(Directory)%(Filename).exe')" />
-      <_TestAppFile Include="@(TestAppExe->'%(RootDir)%(Directory)%(Filename).exe.config')" />
       <_TestAppFile Include="@(TestAppExe->'%(RootDir)%(Directory)%(Filename).pdb')" />
     </ItemGroup>
 

LibGit2Sharp/Core/NativeMethods.cs

@@ -37,7 +37,11 @@ static NativeMethods()
                     // Try to load the .dll from the path explicitly.
                     // If this call succeeds further DllImports will find the library loaded and not attempt to load it again.
                     // If it fails the next DllImport will load the library from safe directories.
+#if NETCORE
                     if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+#else
+                    if (Platform.OperatingSystem == OperatingSystemType.Windows)
+#endif
                     {
                         LoadWindowsLibrary(nativeLibraryPath);
                     }

LibGit2Sharp/Core/Platform.cs

@@ -13,11 +13,16 @@ internal enum OperatingSystemType
     internal static class Platform
     {
         public static string ProcessorArchitecture => IntPtr.Size == 8 ? "x64" : "x86";
+#if !NETCORE
+        private static bool? _isRunningOnMac;
+        public static bool IsRunningOnMac() => _isRunningOnMac ?? (_isRunningOnMac = TryGetIsRunningOnMac()) ?? false;
+#endif
 
         public static OperatingSystemType OperatingSystem
         {
             get
             {
+#if NETCORE
                 if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
                 {
                     return OperatingSystemType.Windows;
@@ -32,7 +37,21 @@ public static OperatingSystemType OperatingSystem
                 {
                     return OperatingSystemType.MacOSX;
                 }
-
+#else
+                var platform = (int)Environment.OSVersion.Platform;
+                if (platform <= 3 || platform == 5)
+                {
+                    return OperatingSystemType.Windows;
+                }
+                if (IsRunningOnMac())
+                {
+                    return OperatingSystemType.MacOSX;
+                }
+                if (platform == 4 || platform == 6 || platform == 128)
+                {
+                    return OperatingSystemType.Unix;
+                }
+#endif
                 throw new PlatformNotSupportedException();
             }
         }
@@ -71,5 +90,45 @@ public static bool IsRunningOnNetFramework()
         /// </summary>
         public static bool IsRunningOnNetCore()
             => typeof(object).Assembly.GetName().Name != "mscorlib";
+
+#if !NETCORE
+#pragma warning disable IDE1006 // Naming Styles
+        [DllImport("libc")]
+        internal static extern int uname(IntPtr buf);
+#pragma warning restore IDE1006 // Naming Styles
+
+        private static bool TryGetIsRunningOnMac()
+        {
+            try
+            {
+                IntPtr buf = IntPtr.Zero;
+                try
+                {
+                    buf = Marshal.AllocHGlobal(8192);
+                    if (uname(buf) == 0)
+                    {
+                        string os = Marshal.PtrToStringAnsi(buf);
+                        if (os == "Darwin")
+                        {
+                            return true;
+                        }
+                    }
+                }
+                finally
+                {
+                    if (buf != IntPtr.Zero)
+                    {
+                        Marshal.FreeHGlobal(buf);
+                    }
+                }
+            }
+            catch
+            {
+                // Ignore any other possible failures on non-OSX platforms
+            }
+
+            return false;
+        }
+#endif
     }
 }

LibGit2Sharp/LibGit2Sharp.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net461</TargetFrameworks>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <Description>LibGit2Sharp brings all the might and speed of libgit2, a native Git implementation, to the managed world of .Net and Mono.</Description>
     <Company>LibGit2Sharp contributors</Company>