Properly Detect & Handle Musl Systems (#1657)

Fixes #1637

binding/Binding.Shared/LibraryLoader.cs

@@ -47,57 +47,24 @@ namespace SkiaSharp
 				var path = typeof (T).Assembly.Location;
 				if (!string.IsNullOrEmpty (path)) {
 					path = Path.GetDirectoryName (path);
-					// 1.1 in platform sub dir
-					var lib = Path.Combine (path, arch, libWithExt);
-					if (File.Exists (lib))
-						return lib;
-					// 1.2 in root
-					lib = Path.Combine (path, libWithExt);
-					if (File.Exists (lib))
-						return lib;
+					if (CheckLibraryPath (path, arch, libWithExt, out var localLib))
+						return localLib;
 				}
 
 				// 2. try current directory
-				path = Directory.GetCurrentDirectory ();
-				if (!string.IsNullOrEmpty (path)) {
-					// 2.1 in platform sub dir
-					var lib = Path.Combine (path, arch, libWithExt);
-					if (File.Exists (lib))
-						return lib;
-					// 2.2 in root
-					lib = Path.Combine (lib, libWithExt);
-					if (File.Exists (lib))
-						return lib;
-				}
+				if (CheckLibraryPath (Directory.GetCurrentDirectory (), arch, libWithExt, out var lib))
+					return lib;
 
 				// 3. try app domain
 				try {
 					if (AppDomain.CurrentDomain is AppDomain domain) {
 						// 3.1 RelativeSearchPath
-						path = domain.RelativeSearchPath;
-						if (!string.IsNullOrEmpty (path)) {
-							// 3.1.1 in platform sub dir
-							var lib = Path.Combine (path, arch, libWithExt);
-							if (File.Exists (lib))
-								return lib;
-							// 3.1.2 in root
-							lib = Path.Combine (lib, libWithExt);
-							if (File.Exists (lib))
-								return lib;
-						}
+						if (CheckLibraryPath (domain.RelativeSearchPath, arch, libWithExt, out lib))
+							return lib;
 
 						// 3.2 BaseDirectory
-						path = domain.BaseDirectory;
-						if (!string.IsNullOrEmpty (path)) {
-							// 3.2.1 in platform sub dir
-							var lib = Path.Combine (path, arch, libWithExt);
-							if (File.Exists (lib))
-								return lib;
-							// 3.2.2 in root
-							lib = Path.Combine (lib, libWithExt);
-							if (File.Exists (lib))
-								return lib;
-						}
+						if (CheckLibraryPath (domain.BaseDirectory, arch, libWithExt, out lib))
+							return lib;
 					}
 				} catch {
 					// no-op as there may not be any domain or path
@@ -106,6 +73,38 @@ namespace SkiaSharp
 				// 4. use PATH or default loading mechanism
 				return libWithExt;
 			}
+
+			static bool CheckLibraryPath(string root, string arch, string libWithExt, out string foundPath)
+			{
+				if (!string.IsNullOrEmpty (root)) {
+					// a. in specific platform sub dir
+					if (!string.IsNullOrEmpty (PlatformConfiguration.LinuxFlavor)) {
+						var muslLib = Path.Combine (root, PlatformConfiguration.LinuxFlavor + "-" + arch, libWithExt);
+						if (File.Exists (muslLib)) {
+							foundPath = muslLib;
+							return true;
+						}
+					}
+
+					// b. in generic platform sub dir
+					var searchLib = Path.Combine (root, arch, libWithExt);
+					if (File.Exists (searchLib)) {
+						foundPath = searchLib;
+						return true;
+					}
+
+					// c. in root
+					searchLib = Path.Combine (root, libWithExt);
+					if (File.Exists (searchLib)) {
+						foundPath = searchLib;
+						return true;
+					}
+				}
+
+				// d. nothing
+				foundPath = null;
+				return false;
+			}
 		}
 
 		public static T GetSymbolDelegate<T> (IntPtr library, string name)
@@ -192,7 +191,7 @@ namespace SkiaSharp
 
 		private static class Linux
 		{
-			private const string SystemLibrary = "libdl.so";
+			private const string SystemLibrary = "dl";
 
 			private const int RTLD_LAZY = 1;
 			private const int RTLD_NOW = 2;

binding/Binding.Shared/PlatformConfiguration.cs

@@ -37,7 +37,6 @@ namespace SkiaSharp
 			var arch = Package.Current.Id.Architecture;
 			const ProcessorArchitecture arm64 = (ProcessorArchitecture)12;
 			IsArm = arch == ProcessorArchitecture.Arm || arch == arm64;
-
 #else
 			IsMac = RuntimeInformation.IsOSPlatform (OSPlatform.OSX);
 			IsLinux = RuntimeInformation.IsOSPlatform (OSPlatform.Linux);
@@ -50,5 +49,50 @@ namespace SkiaSharp
 
 			Is64Bit = IntPtr.Size == 8;
 		}
+
+		private static string linuxFlavor;
+
+		public static string LinuxFlavor
+		{
+			get
+			{
+				if (!IsLinux)
+					return null;
+
+				if (!string.IsNullOrEmpty (linuxFlavor))
+					return linuxFlavor;
+
+				// we only check for musl/glibc right now
+				if (!IsGlibc)
+					return "musl";
+
+				return null;
+			}
+			set => linuxFlavor = value;
+		}
+
+#if WINDOWS_UWP
+		public static bool IsGlibc { get; }
+#else
+		private static readonly Lazy<bool> isGlibcLazy = new Lazy<bool> (IsGlibcImplementation);
+
+		public static bool IsGlibc => IsLinux && isGlibcLazy.Value;
+
+		private static bool IsGlibcImplementation ()
+		{
+			try
+			{
+				gnu_get_libc_version ();
+				return true;
+			}
+			catch (TypeLoadException)
+			{
+				return false;
+			}
+		}
+
+		[DllImport ("c", ExactSpelling = true, CallingConvention = CallingConvention.Cdecl)]
+		private static extern IntPtr gnu_get_libc_version ();
+#endif
 	}
 }

binding/HarfBuzzSharp/nuget/build/net462/HarfBuzzSharp.targets

@@ -45,16 +45,16 @@
 
         <!-- Linux: Musl -->
         <_NativeHarfBuzzSharpFile Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux-musl-x86\native\libHarfBuzzSharp*.so">
-            <Dir>x86\</Dir>
+            <Dir>musl-x86\</Dir>
         </_NativeHarfBuzzSharpFile>
         <_NativeHarfBuzzSharpFile Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux-musl-x64\native\libHarfBuzzSharp*.so">
-            <Dir>x64\</Dir>
+            <Dir>musl-x64\</Dir>
         </_NativeHarfBuzzSharpFile>
         <_NativeHarfBuzzSharpFile Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux-musl-arm\native\libHarfBuzzSharp*.so">
-            <Dir>arm\</Dir>
+            <Dir>musl-arm\</Dir>
         </_NativeHarfBuzzSharpFile>
         <_NativeHarfBuzzSharpFile Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux-musl-arm64\native\libHarfBuzzSharp*.so">
-            <Dir>arm64\</Dir>
+            <Dir>musl-arm64\</Dir>
         </_NativeHarfBuzzSharpFile>
 
         <!-- macOS -->

binding/SkiaSharp/nuget/build/net462/SkiaSharp.targets

@@ -45,16 +45,16 @@
 
         <!-- Linux: Musl -->
         <_NativeSkiaSharpFile Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux-musl-x86\native\libSkiaSharp*.so">
-            <Dir>x86\</Dir>
+            <Dir>musl-x86\</Dir>
         </_NativeSkiaSharpFile>
         <_NativeSkiaSharpFile Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux-musl-x64\native\libSkiaSharp*.so">
-            <Dir>x64\</Dir>
+            <Dir>musl-x64\</Dir>
         </_NativeSkiaSharpFile>
         <_NativeSkiaSharpFile Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux-musl-arm\native\libSkiaSharp*.so">
-            <Dir>arm\</Dir>
+            <Dir>musl-arm\</Dir>
         </_NativeSkiaSharpFile>
         <_NativeSkiaSharpFile Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux-musl-arm64\native\libSkiaSharp*.so">
-            <Dir>arm64\</Dir>
+            <Dir>musl-arm64\</Dir>
         </_NativeSkiaSharpFile>
 
         <!-- macOS -->

tests/Tests/ApiTests.cs

@@ -247,5 +247,17 @@ namespace SkiaSharp.Tests
 		{
 			Assert.Equal(SkiaSharpVersion.Native.ToString(2), SkiaSharpVersion.NativeString);
 		}
+
+		[SkippableFact]
+		public void PlatformConfigurationIsMuslOverrideCanBeFoundViaReflection()
+		{
+			var assembly = typeof(SkiaSharpVersion).Assembly;
+			var config = assembly.DefinedTypes.FirstOrDefault(t => t.Name == "PlatformConfiguration");
+			var overrideProp = config.GetProperty("LinuxFlavor");
+
+			Assert.Equal(typeof(string), overrideProp.PropertyType);
+			Assert.True(overrideProp.CanRead);
+			Assert.True(overrideProp.CanWrite);
+		}
 	}
 }