Fix interop for RTL_OSVERSIONINFOEX (dotnet/corefx#32433)

- Ensure that the OS version string is marshaled as Unicode
- Avoid allocating the version string when it is not needed

Fixes dotnet/corefx#32423

Commit migrated from dotnet/corefx@1a7ef6f

src/libraries/Common/src/Interop/Windows/NtDll/Interop.RTL_OSVERSIONINFOEX.cs

@@ -9,16 +9,15 @@ internal partial class Interop
 {
     internal partial class NtDll
     {
-        [StructLayout(LayoutKind.Sequential)]
-        internal struct RTL_OSVERSIONINFOEX
+        [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
+        internal unsafe struct RTL_OSVERSIONINFOEX
         {
             internal uint dwOSVersionInfoSize;
             internal uint dwMajorVersion;
             internal uint dwMinorVersion;
             internal uint dwBuildNumber;
             internal uint dwPlatformId;
-            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
-            internal string szCSDVersion;
+            internal fixed char szCSDVersion[128];
         }
     }
 }

src/libraries/Common/src/Interop/Windows/NtDll/Interop.RtlGetVersion.cs

@@ -11,17 +11,17 @@ internal partial class Interop
     internal partial class NtDll
     {
         [DllImport(Libraries.NtDll, ExactSpelling=true)]
-        private static extern int RtlGetVersion(out RTL_OSVERSIONINFOEX lpVersionInformation);
+        private static extern int RtlGetVersion(ref RTL_OSVERSIONINFOEX lpVersionInformation);
 
-        internal static string RtlGetVersion()
+        internal static unsafe string RtlGetVersion()
         {
-            RTL_OSVERSIONINFOEX osvi = new RTL_OSVERSIONINFOEX();
-            osvi.dwOSVersionInfoSize = (uint)Marshal.SizeOf(osvi);
+            var osvi = new RTL_OSVERSIONINFOEX();
+            osvi.dwOSVersionInfoSize = (uint)sizeof(RTL_OSVERSIONINFOEX);
             const string version = "Microsoft Windows";
-            if (RtlGetVersion(out osvi) == 0)
+            if (RtlGetVersion(ref osvi) == 0)
             {
                 return string.Format("{0} {1}.{2}.{3} {4}",
-                    version, osvi.dwMajorVersion, osvi.dwMinorVersion, osvi.dwBuildNumber, osvi.szCSDVersion);
+                    version, osvi.dwMajorVersion, osvi.dwMinorVersion, osvi.dwBuildNumber, new string(&(osvi.szCSDVersion[0])));
             }
             else
             {

src/libraries/CoreFx.Private.TestUtilities/src/System/PlatformDetection.Windows.cs

@@ -219,19 +219,19 @@ private static int GetWindowsProductType()
             return productType;
         }
 
-        private static int GetWindowsMinorVersion()
+        private static unsafe int GetWindowsMinorVersion()
         {
-            RTL_OSVERSIONINFOEX osvi = new RTL_OSVERSIONINFOEX();
-            osvi.dwOSVersionInfoSize = (uint)Marshal.SizeOf(osvi);
-            Assert.Equal(0, RtlGetVersion(out osvi));
+            var osvi = new RTL_OSVERSIONINFOEX();
+            osvi.dwOSVersionInfoSize = (uint)sizeof(RTL_OSVERSIONINFOEX);
+            Assert.Equal(0, RtlGetVersion(ref osvi));
             return (int)osvi.dwMinorVersion;
         }
 
-        private static int GetWindowsBuildNumber()
+        private static unsafe int GetWindowsBuildNumber()
         {
-            RTL_OSVERSIONINFOEX osvi = new RTL_OSVERSIONINFOEX();
-            osvi.dwOSVersionInfoSize = (uint)Marshal.SizeOf(osvi);
-            Assert.Equal(0, RtlGetVersion(out osvi));
+            var osvi = new RTL_OSVERSIONINFOEX();
+            osvi.dwOSVersionInfoSize = (uint)sizeof(RTL_OSVERSIONINFOEX);
+            Assert.Equal(0, RtlGetVersion(ref osvi));
             return (int)osvi.dwBuildNumber;
         }
 
@@ -269,25 +269,24 @@ out int pdwReturnedProductType
         );
 
         [DllImport("ntdll.dll", ExactSpelling=true)]
-        private static extern int RtlGetVersion(out RTL_OSVERSIONINFOEX lpVersionInformation);
+        private static extern int RtlGetVersion(ref RTL_OSVERSIONINFOEX lpVersionInformation);
 
-        [StructLayout(LayoutKind.Sequential)]
-        private struct RTL_OSVERSIONINFOEX
+        [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
+        private unsafe struct RTL_OSVERSIONINFOEX
         {
             internal uint dwOSVersionInfoSize;
             internal uint dwMajorVersion;
             internal uint dwMinorVersion;
             internal uint dwBuildNumber;
             internal uint dwPlatformId;
-            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
-            internal string szCSDVersion;
+            internal fixed char szCSDVersion[128];
         }
 
-        private static int GetWindowsVersion()
+        private static unsafe int GetWindowsVersion()
         {
-            RTL_OSVERSIONINFOEX osvi = new RTL_OSVERSIONINFOEX();
-            osvi.dwOSVersionInfoSize = (uint)Marshal.SizeOf(osvi);
-            Assert.Equal(0, RtlGetVersion(out osvi));
+            var osvi = new RTL_OSVERSIONINFOEX();
+            osvi.dwOSVersionInfoSize = (uint)sizeof(RTL_OSVERSIONINFOEX);
+            Assert.Equal(0, RtlGetVersion(ref osvi));
             return (int)osvi.dwMajorVersion;
         }
 
@@ -303,5 +302,5 @@ private static int GetWindowsVersion()
         // The process handle does NOT need closing
         [DllImport("kernel32.dll", ExactSpelling = true)]
         private static extern IntPtr GetCurrentProcess();
- }
+    }
 }

src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System.Runtime.InteropServices.RuntimeInformation.csproj

@@ -2,6 +2,7 @@
   <PropertyGroup>
     <RootNamespace>System.Runtime.InteropServices</RootNamespace>
     <ProjectGuid>{1CBC030D-B5D3-4AB5-A9FD-24EC5F6F38D2}</ProjectGuid>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <Configurations>netcoreapp-Unix-Debug;netcoreapp-Unix-Release;netcoreapp-Windows_NT-Debug;netcoreapp-Windows_NT-Release;uap-Windows_NT-Debug;uap-Windows_NT-Release;uapaot-Windows_NT-Debug;uapaot-Windows_NT-Release</Configurations>
   </PropertyGroup>
   <ItemGroup>