Fix AVE in PtrToString on .NET 8 & remove unnecessary marshalling (do…

…tnet#1990)

* Fix AVE in PtrToString on .NET 8 & remove unnecessary marshalling

* Review comments

src/Core/Silk.NET.Core/Native/SilkMarshal.cs

@@ -512,19 +512,53 @@ public static string[] MemoryToStringArray
  Func<nint, string> customUnmarshaller
  ) => PtrToStringArray(input, input.Length / IntPtr.Size, customUnmarshaller);
 
- private static unsafe string Utf8PtrToString(nint ptr)
+ /// <summary>
+ /// Gets the length of the given native string.
+ /// </summary>
+ /// <param name="ptr">The native string pointer.</param>
+ /// <param name="encoding">The encoding.</param>
+ /// <returns>The length of the string.</returns>
+ /// <remarks>
+ /// Note that this returns the length in characters. Namely, if a 16-bit character encoding is used, the actual
+ /// byte count will be double the return value from this function.
+ /// </remarks>
+#if NET6_0_OR_GREATER
+ [MethodImpl(MethodImplOptions.AggressiveInlining)]
+ public static unsafe nuint StringLength(
+ nint ptr,
+ NativeStringEncoding encoding = NativeStringEncoding.Ansi
+ ) =>
+ (nuint)(
+ encoding == NativeStringEncoding.LPWStr
+ ? MemoryMarshal.CreateReadOnlySpanFromNullTerminated((char*)ptr).Length
+ : MemoryMarshal.CreateReadOnlySpanFromNullTerminated((byte*)ptr).Length
+ );
+#else
+ public static unsafe nuint StringLength(
+ nint ptr,
+ NativeStringEncoding encoding = NativeStringEncoding.Ansi
+ )
  {
- var span = new Span<byte>((void*) ptr, int.MaxValue);
- span = span.Slice(0, span.IndexOf(default(byte)));
- if (span.Length == 0)
+ if (ptr == 0)
  {
- return string.Empty;
+ return 0;
  }
+ nuint ret;
+ for (
+ ret = 0;
+ encoding == NativeStringEncoding.LPWStr
+ ? ((char*)ptr)![ret] != 0
+ : ((byte*)ptr)![ret] != 0;
+ ret++
+ ) { }
+ return ret;
+ }
+#endif
 
-  fixed (byte* bytes = span)
-  {
-  return Encoding.UTF8.GetString(bytes, span.Length);
- }
+ private static unsafe string Utf8PtrToString(nint ptr)
+ {
+ var len = (int)StringLength(ptr, NativeStringEncoding.UTF8);
+ return len == 0 ? string.Empty : Encoding.UTF8.GetString((byte*)ptr, len);
  }
 
  // "Unsafe" methods

src/Core/Silk.NET.SilkTouch/Middlewares/StringMarshaller.cs

@@ -119,10 +119,13 @@ public static void StringMarshaller(ref IMarshalContext ctx, Action next)
  )
  )
  );
- ctx.DeclareExtraRef(id); // readback
+ if (ctx.MethodSymbol.Parameters[index].RefKind is RefKind.Ref)
+ {
+ ctx.DeclareExtraRef(id); // readback
+ ctx.DeclareExtraRef(ctx.ParameterVariables[index]); // ptrToString
+ }
  ctx.DeclareExtraRef(id); // free
  ctx.SetParameterToVariable(index, id);
- ctx.DeclareExtraRef(ctx.ParameterVariables[index]); // ptrToString
  break;
  case RefKind.Out:
  {
@@ -263,8 +266,7 @@ public static void StringMarshaller(ref IMarshalContext ctx, Action next)
 
  var marshalAs = ctx.ParameterMarshalOptions[index]?.UnmanagedType ?? Default;
 
- if (ctx.MethodSymbol.Parameters[index].RefKind == RefKind.None ||
- ctx.MethodSymbol.Parameters[index].RefKind == RefKind.Ref ||
+ if (ctx.MethodSymbol.Parameters[index].RefKind == RefKind.Ref ||
  ctx.MethodSymbol.Parameters[index].RefKind == RefKind.Out)
  {
  var p2 = ctx.ResolveVariable(ctx.ParameterVariables[index]);

src/Windowing/Silk.NET.GLFW/GlfwProvider.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using Silk.NET.Core.Native;
 
 namespace Silk.NET.GLFW
 {
@@ -26,7 +27,7 @@ private static unsafe Glfw GetGlfw()
  if (!glfw.Init())
  {
  var code = glfw.GetError(out var pDesc);
- var len = new ReadOnlySpan<byte>(pDesc, int.MaxValue).IndexOf((byte) '\0');
+ var len = (int)SilkMarshal.StringLength((nint)pDesc);
  var desc = len <= 0 ? "Unknown" : System.Text.Encoding.UTF8.GetString(pDesc, len);
  throw new GlfwException($"GLFW Init failed, {code}: {desc}");
  }