Manually generate signatures for some PInvokes to handle SetLastError. (

#1354)

* Manually generate signatures to handle SetLastError.

* Use new signatures on .NET 6 and newer.

* Use sbyte*

---------

Co-authored-by: Manodasan Wignarajah <mawign@microsoft.com>

src/cswinrt/strings/WinRT.cs

@@ -47,14 +47,55 @@ internal static unsafe int CoCreateInstance(ref Guid clsid, IntPtr outer, uint c
         internal static extern int CoDecrementMTAUsage(IntPtr cookie);
 
         [DllImport("api-ms-win-core-com-l1-1-0.dll")]
-        internal static extern unsafe int CoIncrementMTAUsage(IntPtr* cookie);
+        internal static extern unsafe int CoIncrementMTAUsage(IntPtr* cookie);
+
+#if NET6_0_OR_GREATER
+        internal static bool FreeLibrary(IntPtr moduleHandle)
+        {
+            int lastError;
+            bool returnValue;
+            int nativeReturnValue;
+            {
+                Marshal.SetLastSystemError(0);
+                nativeReturnValue = PInvoke(moduleHandle);
+                lastError = Marshal.GetLastSystemError();
+            }
 
+            // Unmarshal - Convert native data to managed data.
+            returnValue = nativeReturnValue != 0;
+            Marshal.SetLastPInvokeError(lastError);
+            return returnValue;
+
+            // Local P/Invoke
+            [DllImportAttribute("kernel32.dll", EntryPoint = "FreeLibrary", ExactSpelling = true)]
+            static extern unsafe int PInvoke(IntPtr nativeModuleHandle);
+        }
+
+        internal static unsafe void* TryGetProcAddress(IntPtr moduleHandle, sbyte* functionName)
+        {
+            int lastError;
+            void* returnValue;
+            {
+                Marshal.SetLastSystemError(0);
+                returnValue = PInvoke(moduleHandle, functionName);
+                lastError = Marshal.GetLastSystemError();
+            }
+
+            Marshal.SetLastPInvokeError(lastError);
+            return returnValue;
+
+            // Local P/Invoke
+            [DllImportAttribute("kernel32.dll", EntryPoint = "GetProcAddress", ExactSpelling = true)]
+            static extern unsafe void* PInvoke(IntPtr nativeModuleHandle, sbyte* nativeFunctionName);
+        }
+#else
         [DllImport("kernel32.dll", SetLastError = true)]
         [return: MarshalAs(UnmanagedType.Bool)]
         internal static extern bool FreeLibrary(IntPtr moduleHandle);
 
         [DllImport("kernel32.dll", EntryPoint = "GetProcAddress", SetLastError = true, BestFitMapping = false)]
         internal static unsafe extern void* TryGetProcAddress(IntPtr moduleHandle, sbyte* functionName);
+#endif
 
         internal static unsafe void* TryGetProcAddress(IntPtr moduleHandle, ReadOnlySpan<byte> functionName)
         {
@@ -130,17 +171,36 @@ internal static unsafe int CoCreateInstance(ref Guid clsid, IntPtr outer, uint c
                 Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error(), new IntPtr(-1));
             }
             return functionPtr;
-        }
-
+        }
+
+#if NET6_0_OR_GREATER
+        internal static unsafe IntPtr LoadLibraryExW(ushort* fileName, IntPtr fileHandle, uint flags)
+        {
+            int lastError;
+            IntPtr returnValue;
+            {
+                Marshal.SetLastSystemError(0);
+                returnValue = PInvoke(fileName, fileHandle, flags);
+                lastError = Marshal.GetLastSystemError();
+            }
+
+            Marshal.SetLastPInvokeError(lastError);
+            return returnValue;
+
+            // Local P/Invoke
+            [DllImportAttribute("kernel32.dll", EntryPoint = "LoadLibraryExW", ExactSpelling = true)]
+            static extern unsafe IntPtr PInvoke(ushort* nativeFileName, IntPtr nativeFileHandle, uint nativeFlags);
+        }
+#else
         [DllImport("kernel32.dll", SetLastError = true)]
         internal static unsafe extern IntPtr LoadLibraryExW(ushort* fileName, IntPtr fileHandle, uint flags);
-
+#endif
         internal static unsafe IntPtr LoadLibraryExW(string fileName, IntPtr fileHandle, uint flags)
         {
             fixed (char* lpFileName = fileName)
                 return LoadLibraryExW((ushort*)lpFileName, fileHandle, flags);
         }
-
+
         [DllImport("api-ms-win-core-winrt-l1-1-0.dll")]
         internal static extern unsafe int RoGetActivationFactory(IntPtr runtimeClassId, Guid* iid, IntPtr* factory);