Microsoft.IO.Redist part (and a build fix)

CHILD: .NET CORE | ElevationOfPrivilege: Microsoft.IO.Redist part (and a build fix)

It turned out that https://dev.azure.com/dnceng/internal/_git/dotnet-runtime/pullrequest/39614 was incomplete and caused a build break. The code was compiling fine for the default config (.NET 6), but not Full Framework, which includes Microsoft.IO.Redist which compiles the affected files.

I could not use exact same fix for Framework as for 6.0 as the code was using umanaged function pointers and causing error CS8889, so I've applied the same fix I did for Full Framework.

Author: Adam Sitnik

src/libraries/Common/src/Interop/Windows/Kernel32/Interop.GetProcAddress.cs

@@ -10,8 +10,10 @@ internal static partial class Interop
 {
     internal static partial class Kernel32
     {
+#if !MS_IO_REDIST // SafeLibraryHandle is inaccessible due to its protection level
         [DllImport(Libraries.Kernel32, CharSet = CharSet.Ansi, BestFitMapping = false)]
         public static extern IntPtr GetProcAddress(SafeLibraryHandle hModule, string lpProcName);
+#endif
 
         [DllImport(Libraries.Kernel32, CharSet = CharSet.Ansi, BestFitMapping = false)]
         public static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);

src/libraries/Common/src/Interop/Windows/Kernel32/Interop.GetTempPathW.cs

@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.InteropServices;
+
+internal static partial class Interop
+{
+    internal static partial class Kernel32
+    {
+        [DllImport(Libraries.Kernel32, CharSet = CharSet.Unicode, BestFitMapping = false, ExactSpelling = true)]
+        internal static extern uint GetTempPathW(int bufferLen, ref char buffer);
+
+        [DllImport(Libraries.Kernel32, CharSet = CharSet.Unicode, BestFitMapping = false, ExactSpelling = true)]
+        internal static extern uint GetTempPath2W(int bufferLen, ref char buffer);
+    }
+}

src/libraries/Microsoft.IO.Redist/src/Microsoft.IO.Redist.csproj

@@ -1,6 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <IsPackable>true</IsPackable>
+    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+    <ServicingVersion>1</ServicingVersion>
     <PackageDescription>Downlevel support package for System.IO classes.</PackageDescription>
     <DefineConstants>$(DefineConstants);MS_IO_REDIST</DefineConstants>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
@@ -108,6 +110,10 @@
              Link="Interop\Windows\Interop.GetTempFileNameW.cs" />
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.GetTempPathW.cs"
              Link="Interop\Windows\Kernel32\Interop.GetTempPathW.cs" />
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.GetModuleHandle.cs"
+             Link="Interop\Windows\Kernel32\Interop.GetModuleHandle.cs" />
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.GetProcAddress.cs"
+             Link="Interop\Windows\Kernel32\Interop.GetProcAddress.cs" />
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.MAX_PATH.cs"
              Link="Interop\Windows\Interop.MAX_PATH.cs" />
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.REPARSE_DATA_BUFFER.cs"

src/libraries/System.Private.CoreLib/src/System/IO/Path.Windows.cs

@@ -17,7 +17,11 @@ namespace System.IO
 {
     public static unsafe partial class Path
     {
+#if MS_IO_REDIST
+        private static volatile int s_GetTempPathVersion;
+#else
         private static volatile delegate* unmanaged<int, char*, uint> s_GetTempPathWFunc;
+#endif
 
         public static char[] GetInvalidFileNameChars() => new char[]
         {
@@ -155,6 +159,20 @@ public static string GetTempPath()
             return path;
         }
 
+#if MS_IO_REDIST
+        private static int GetGetTempPathVersion()
+        {
+            IntPtr kernel32 = Interop.Kernel32.GetModuleHandle(Interop.Libraries.Kernel32);
+            if (kernel32 != IntPtr.Zero)
+            {
+                if (Interop.Kernel32.GetProcAddress(kernel32, "GetTempPath2W") != IntPtr.Zero)
+                {
+                    return 2;
+                }
+            }
+            return 1;
+        }
+#else
         private static unsafe delegate* unmanaged<int, char*, uint> GetGetTempPathWFunc()
         {
             IntPtr kernel32 = Interop.Kernel32.LoadLibraryEx(Interop.Libraries.Kernel32, IntPtr.Zero, Interop.Kernel32.LOAD_LIBRARY_SEARCH_SYSTEM32);
@@ -166,6 +184,7 @@ public static string GetTempPath()
 
             return (delegate* unmanaged<int, char*, uint>)func;
         }
+#endif
 
         internal static void GetTempPath(ref ValueStringBuilder builder)
         {
@@ -183,6 +202,16 @@ internal static void GetTempPath(ref ValueStringBuilder builder)
 
             static uint GetTempPathW(int bufferLen, ref char buffer)
             {
+#if MS_IO_REDIST
+                int getTempPathVersion = s_GetTempPathVersion;
+                if (getTempPathVersion == 0)
+                {
+                    s_GetTempPathVersion = getTempPathVersion = GetGetTempPathVersion();
+                }
+                return getTempPathVersion == 2
+                    ? Interop.Kernel32.GetTempPath2W(bufferLen, ref buffer)
+                    : Interop.Kernel32.GetTempPathW(bufferLen, ref buffer);
+#else
                 delegate* unmanaged<int, char*, uint> func = s_GetTempPathWFunc;
                 if (func == null)
                 {
@@ -200,6 +229,7 @@ static uint GetTempPathW(int bufferLen, ref char buffer)
 
                 Marshal.SetLastPInvokeError(lastError);
                 return retVal;
+#endif
             }
         }