Alternate fix for #3817: re-entrant static-init NRE in SKTypeface (+ #4080 test suite)

binding/SkiaSharp/SKBlender.cs

@@ -88,6 +88,7 @@ private sealed class SKBlenderStatic : SKBlender
 		internal SKBlenderStatic (IntPtr x)
 			: base (x, false)
 		{
+			PreventPublicDisposal ();
 		}
 
 		protected override void Dispose (bool disposing) { }

binding/SkiaSharp/SKColorFilter.cs

@@ -164,6 +164,7 @@ private sealed class SKColorFilterStatic : SKColorFilter
 			internal SKColorFilterStatic (IntPtr x)
 				: base (x, false)
 			{
+				PreventPublicDisposal ();
 			}
 
 			protected override void Dispose (bool disposing) { }

binding/SkiaSharp/SKColorSpace.cs

@@ -166,6 +166,7 @@ private sealed class SKColorSpaceStatic : SKColorSpace
 			internal SKColorSpaceStatic (IntPtr x)
 				: base (x, false)
 			{
+				PreventPublicDisposal ();
 			}
 
 			protected override void Dispose (bool disposing) { }

binding/SkiaSharp/SKData.cs

@@ -320,6 +320,7 @@ private sealed class SKDataStatic : SKData
 			internal SKDataStatic (IntPtr x)
 				: base (x, false)
 			{
+				PreventPublicDisposal ();
 			}
 
 			protected override void Dispose (bool disposing) { }

binding/SkiaSharp/SKFontManager.cs

@@ -207,6 +207,7 @@ private sealed class SKFontManagerStatic : SKFontManager
 			internal SKFontManagerStatic (IntPtr x)
 				: base (x, false)
 			{
+				PreventPublicDisposal ();
 			}
 
 			protected override void Dispose (bool disposing) { }

binding/SkiaSharp/SKFontStyle.cs

@@ -69,6 +69,7 @@ private sealed class SKFontStyleStatic : SKFontStyle
 			internal SKFontStyleStatic (SKFontStyleWeight weight, SKFontStyleWidth width, SKFontStyleSlant slant)
 				: base (weight, width, slant)
 			{
+				PreventPublicDisposal ();
 			}
 
 			protected override void Dispose (bool disposing) { }

binding/SkiaSharp/SKPaint.cs

@@ -95,7 +95,10 @@ public void Reset () =>
 
 		private sealed class SKFontStatic : SKFont
 		{
-			internal SKFontStatic (IntPtr handle) : base (handle, false) { }
+			internal SKFontStatic (IntPtr handle) : base (handle, false)
+			{
+				PreventPublicDisposal ();
+			}
 
 			protected override void Dispose (bool disposing) { }
 		}

binding/SkiaSharp/SKTypeface.cs

@@ -22,15 +22,36 @@ static SKTypeface ()
 
 			empty = new SKTypefaceStatic (SkiaApi.sk_typeface_create_empty ());
 
-			// Use legacyMakeTypeface(null) to get the platform default — this uses
-			// fDefaultStyleSet on Android (which searches "sans-serif", "Roboto",
-			// then falls back to style set 0). matchFamilyStyle(null) doesn't work
-			// on Android/NDK/Custom because onMatchFamily(null) returns null.
-			var matched = SkiaApi.sk_fontmgr_legacy_create_typeface (
-				SKFontManager.Default.Handle, IntPtr.Zero, SKFontStyle.Normal.Handle);
-			defaultTypeface = matched == IntPtr.Zero
-				? empty
-				: new SKTypefaceStatic (matched);
+			// Obtain the default font manager and font style as raw native handles
+			// instead of reading the SKFontManager.Default / SKFontStyle.Normal managed
+			// singletons. Those singletons are SKObject types whose static constructors
+			// participate in the same eager-initialization cascade (see
+			// SKObject.EnsureStaticInstanceAreInitialized). Reading them here can re-enter
+			// a static constructor that is still running on the current thread and observe
+			// a not-yet-assigned (null) singleton, throwing a NullReferenceException.
+			// See issue #3817.
+			var fontManager = IntPtr.Zero;
+			var fontStyle = IntPtr.Zero;
+			try {
+				fontManager = SkiaApi.sk_fontmgr_create_default ();
+				fontStyle = SkiaApi.sk_fontstyle_new (
+					(int)SKFontStyleWeight.Normal, (int)SKFontStyleWidth.Normal, SKFontStyleSlant.Upright);
+
+				// Use legacyMakeTypeface(null) to get the platform default — this uses
+				// fDefaultStyleSet on Android (which searches "sans-serif", "Roboto",
+				// then falls back to style set 0). matchFamilyStyle(null) doesn't work
+				// on Android/NDK/Custom because onMatchFamily(null) returns null.
+				var matched = SkiaApi.sk_fontmgr_legacy_create_typeface (
+					fontManager, IntPtr.Zero, fontStyle);
+				defaultTypeface = matched == IntPtr.Zero
+					? empty
+					: new SKTypefaceStatic (matched);
+			} finally {
+				if (fontStyle != IntPtr.Zero)
+					SkiaApi.sk_fontstyle_delete (fontStyle);
+				if (fontManager != IntPtr.Zero)
+					SkiaApi.sk_fontmgr_unref (fontManager);
+			}
 		}
 
 		internal static void EnsureStaticInstanceAreInitialized ()
@@ -454,6 +475,7 @@ private sealed class SKTypefaceStatic : SKTypeface
 			internal SKTypefaceStatic (IntPtr x)
 				: base (x, false)
 			{
+				PreventPublicDisposal ();
 			}
 
 			protected override void Dispose (bool disposing) { }

scripts/infra/tests/tests-netcore.cake

@@ -28,6 +28,7 @@ Task ("Default")
     var tfm = "net10.0";
     var testAssemblies = new List<string> {
         "SkiaSharp.Tests.Console",
+        "SkiaSharp.Tests.SingletonInit.Console",
         "SkiaSharp.Vulkan.Tests.Console",
         "SkiaSharp.Direct3D.Tests.Console",
     };

scripts/infra/tests/tests-netfx.cake

@@ -27,6 +27,7 @@ Task ("Default")
         var tfm = "net48";
         var testAssemblies = new List<string> {
             "SkiaSharp.Tests.Console",
+            "SkiaSharp.Tests.SingletonInit.Console",
             "SkiaSharp.Vulkan.Tests.Console",
             "SkiaSharp.Direct3D.Tests.Console",
         };

tests/SkiaSharp.Tests.Console.sln

@@ -11,6 +11,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkiaSharp.HarfBuzz", "..\so
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkiaSharp.Tests.Console", "SkiaSharp.Tests.Console\SkiaSharp.Tests.Console.csproj", "{8E5284C3-5AAF-4902-B12F-84E9172F20E0}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkiaSharp.Tests.SingletonInit.Console", "SkiaSharp.Tests.SingletonInit.Console\SkiaSharp.Tests.SingletonInit.Console.csproj", "{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}"
+EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkiaSharp.Vulkan.Tests.Console", "SkiaSharp.Vulkan.Tests.Console\SkiaSharp.Vulkan.Tests.Console.csproj", "{9C3F6513-7B66-4DF3-ADBA-1030FEE9C111}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkiaSharp.Vulkan.SharpVk", "..\source\SkiaSharp.Vulkan\SkiaSharp.Vulkan.SharpVk\SkiaSharp.Vulkan.SharpVk.csproj", "{A53DD2E5-55C4-4F7C-9316-D7FAD9A6F19F}"
@@ -85,6 +87,18 @@ Global
 		{8E5284C3-5AAF-4902-B12F-84E9172F20E0}.Release|x64.Build.0 = Release|x64
 		{8E5284C3-5AAF-4902-B12F-84E9172F20E0}.Release|x86.ActiveCfg = Release|x86
 		{8E5284C3-5AAF-4902-B12F-84E9172F20E0}.Release|x86.Build.0 = Release|x86
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Debug|x64.ActiveCfg = Debug|x64
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Debug|x64.Build.0 = Debug|x64
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Debug|x86.ActiveCfg = Debug|x86
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Debug|x86.Build.0 = Debug|x86
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Release|x64.ActiveCfg = Release|x64
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Release|x64.Build.0 = Release|x64
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Release|x86.ActiveCfg = Release|x86
+		{B7E2F4A1-3C5D-4E6F-9A8B-1C2D3E4F5A6B}.Release|x86.Build.0 = Release|x86
 		{9C3F6513-7B66-4DF3-ADBA-1030FEE9C111}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{9C3F6513-7B66-4DF3-ADBA-1030FEE9C111}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{9C3F6513-7B66-4DF3-ADBA-1030FEE9C111}.Debug|x64.ActiveCfg = Debug|x64

tests/SkiaSharp.Tests.SingletonInit.Console/SKSingletonInitTest.cs

@@ -0,0 +1,33 @@
+using System;
+using SkiaSharp;
+using Xunit;
+
+namespace SkiaSharp.Tests.SingletonInit
+{
+	// Regression guard for https://github.com/mono/SkiaSharp/issues/3817.
+	//
+	// Touching SKFontManager.Default as the very first SkiaSharp type in a fresh
+	// process used to throw a TypeInitializationException: the SKObject static
+	// constructor eagerly initializes a cascade of singletons, and the SKTypeface
+	// initializer in that cascade read the managed SKFontManager.Default and
+	// SKFontStyle.Normal singletons. When SKFontManager was the first type touched,
+	// that re-entered the still-running SKFontManager/SKFontStyle initializer on the
+	// same thread and observed a not-yet-assigned (null) singleton, producing a
+	// NullReferenceException surfaced as a TypeInitializationException.
+	//
+	// This assembly intentionally contains a single test so that this is genuinely
+	// the first SkiaSharp access in the process.
+	public class SKSingletonInitTest
+	{
+		[Fact]
+		public void TouchingFontManagerDefaultFirstDoesNotThrow ()
+		{
+			var fontManager = SKFontManager.Default;
+
+			Assert.NotNull (fontManager);
+			Assert.NotEqual (IntPtr.Zero, fontManager.Handle);
+			Assert.NotEqual (IntPtr.Zero, SKFontStyle.Normal.Handle);
+			Assert.NotEqual (IntPtr.Zero, SKTypeface.Default.Handle);
+		}
+	}
+}

tests/SkiaSharp.Tests.SingletonInit.Console/SkiaSharp.Tests.SingletonInit.Console.csproj

@@ -0,0 +1,38 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <!--
+    Issue #3817 regression guard. This is a dedicated test assembly that contains a
+    single test which touches SKFontManager.Default as the FIRST SkiaSharp type in
+    the process. Because static constructors run once per process and "dotnet test"
+    launches a separate test host per assembly, this naturally reproduces the
+    "first type touched" scenario that used to crash the SKObject static-constructor
+    eager-initialization cascade. Keeping it in its own assembly is what guarantees
+    the ordering — do not add other tests or types that touch SkiaSharp here.
+  -->
+
+  <PropertyGroup>
+    <TargetFrameworks>$(TFMCurrent)</TargetFrameworks>
+    <TargetFrameworks Condition="$(IsWindows)">$(TargetFrameworks);net48</TargetFrameworks>
+    <RootNamespace>SkiaSharp.Tests.SingletonInit</RootNamespace>
+    <AssemblyName>SkiaSharp.Tests.SingletonInit</AssemblyName>
+    <SignAssembly>false</SignAssembly>
+    <SkipGenerateAssemblyVersionInfo>true</SkipGenerateAssemblyVersionInfo>
+    <SkipMDocGenerateDocs>true</SkipMDocGenerateDocs>
+    <Platforms>AnyCPU;x64;x86</Platforms>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.2" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2" />
+    <PackageReference Include="XunitXml.TestLogger" Version="3.0.78" />
+    <PackageReference Include="coverlet.msbuild" Version="10.0.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\binding\SkiaSharp\SkiaSharp.csproj" />
+  </ItemGroup>
+
+  <Import Project="..\..\binding\IncludeNativeAssets.SkiaSharp.targets" />
+
+</Project>

tests/Tests/SkiaSharp/HandleDictionaryThreadingCollection.cs

@@ -0,0 +1,32 @@
+using Xunit;
+
+namespace SkiaSharp.Tests
+{
+	// The dedicated white-box concurrency/lifecycle tests for HandleDictionary/SKObject drive their own
+	// deterministic interleavings (via gates and barriers on dedicated OS threads) and then join those
+	// threads against tight deadlines. A failed join is the signal for a genuine product deadlock.
+	//
+	// Under xUnit's default parallelism EVERY test class is its own collection and runs concurrently, and
+	// EVERY SKObject create/dispose/lookup across the whole suite contends on the single global
+	// HandleDictionary lock. On Windows that lock is a Win32 CRITICAL_SECTION (the #1383 STA-pump fix) with
+	// no reader concurrency, so the entire parallel suite serializes through one mutex. On a small/slow CI
+	// agent this can starve a parked dispose thread of CPU/lock ownership for >10s and trip these tight
+	// deadlines — a false "deadlock" that has nothing to do with the code under test.
+	//
+	// Placing all of these classes in one DisableParallelization collection makes them run sequentially in
+	// xUnit's non-parallel phase, AFTER the parallel phase has drained, so nothing else is hammering the
+	// global lock while their deadlines are ticking. This does NOT weaken coverage: each test produces its
+	// own interleaving, and the rest of the suite still exercises the global lock in parallel during the
+	// parallel phase.
+	//
+	// SKManagedStreamConcurrencyTest joins this collection for the same reason: its gated "public Dispose
+	// while a native lazy read is in-flight" tests park a real OS thread inside a managed Stream.Read() and
+	// then race a public Dispose against codec teardown under a 30s join deadline. Running it in the
+	// drained non-parallel phase removes both the global-lock contention above AND any thread-pool
+	// starvation, so the parked reader and the racing disposer always get CPU before the deadline.
+	[CollectionDefinition (HandleDictionaryThreadingCollection.Name, DisableParallelization = true)]
+	public sealed class HandleDictionaryThreadingCollection
+	{
+		public const string Name = "HandleDictionary threading (serialized)";
+	}
+}

tests/Tests/SkiaSharp/SKCodecTest.cs

@@ -116,8 +116,11 @@ public unsafe void InvalidStreamIsDisposedImmediately()
 
 			Assert.Null(SKCodec.Create(stream));
 
+			// Failed Create has no new native owner, so RevokeOwnership(null) runs
+			// DisposeInternal(): the wrapper is genuinely disposed and deregistered,
+			// not merely public-dispose-guarded. Hence IsDisposed (not IgnorePublicDispose).
 			Assert.False(stream.OwnsHandle);
-			Assert.True(stream.IgnorePublicDispose);
+			Assert.True(stream.IsDisposed);
 			Assert.False(SKObject.GetInstance<SKStream>(handle, out _));
 		}
 
@@ -492,5 +495,36 @@ public void CanDecodeData(string image)
 			Assert.Equal(SKCodecResult.Success, codec.GetPixels(out var pixels));
 			Assert.NotEmpty(pixels);
 		}
+
+		[SkippableFact]
+		public void CanDecodeManagedStreamAfterCreate()
+		{
+			// Regression: SKCodec.Create(Stream) wraps the managed .NET stream and the
+			// codec decodes lazily. The underlying managed stream MUST stay readable
+			// until the codec is disposed — the singleton/lifecycle rework must not let
+			// the reparented wrapper's ownership transfer eagerly close the .NET stream.
+			using var stream = new MemoryStream(File.ReadAllBytes(Path.Combine(PathToImages, "baboon.png")));
+			using var codec = SKCodec.Create(stream);
+			Assert.NotNull(codec);
+
+			Assert.Equal(SKCodecResult.Success, codec.GetPixels(out var pixels));
+			Assert.NotEmpty(pixels);
+		}
+
+		[SkippableFact]
+		public void CanDecodeNonSeekableManagedStreamAfterCreate()
+		{
+			// Non-seekable managed streams route through SKFrontBufferedManagedStream
+			// (a nested SKManagedStream). The lazy decode must still reach the underlying
+			// .NET stream through the front buffer + nested wrapper without it being
+			// closed early by the ownership transfer.
+			using var backing = new MemoryStream(File.ReadAllBytes(Path.Combine(PathToImages, "baboon.png")));
+			using var nonSeekable = new NonSeekableReadOnlyStream(backing);
+			using var codec = SKCodec.Create(nonSeekable);
+			Assert.NotNull(codec);
+
+			Assert.Equal(SKCodecResult.Success, codec.GetPixels(out var pixels));
+			Assert.NotEmpty(pixels);
+		}
 	}
 }

tests/Tests/SkiaSharp/SKColorFilterTest.cs

@@ -11,11 +11,13 @@ public class SKColorFilterTest : SKTest
 		[Trait(Traits.Category.Key, Traits.Category.Values.Smoke)]
 		public void StaticSrgbToLinearIsReturnedAsTheStaticInstance()
 		{
+			var expected = SKColorFilter.CreateSrgbToLinearGamma();
 			var handle = SkiaApi.sk_colorfilter_new_srgb_to_linear_gamma();
 			try
 			{
 				var cs = SKColorFilter.GetObject(handle);
-				Assert.Equal("SKColorFilterStatic", cs.GetType().Name);
+				Assert.Same(expected, cs);
+				Assert.True(cs.IgnorePublicDispose);
 			}
 			finally
 			{
@@ -26,11 +28,13 @@ public void StaticSrgbToLinearIsReturnedAsTheStaticInstance()
 		[SkippableFact]
 		public void StaticLinearToSrgbIsReturnedAsTheStaticInstance()
 		{
+			var expected = SKColorFilter.CreateLinearToSrgbGamma();
 			var handle = SkiaApi.sk_colorfilter_new_linear_to_srgb_gamma();
 			try
 			{
 				var cs = SKColorFilter.GetObject(handle);
-				Assert.Equal("SKColorFilterStatic", cs.GetType().Name);
+				Assert.Same(expected, cs);
+				Assert.True(cs.IgnorePublicDispose);
 			}
 			finally
 			{