Imported Upstream version 6.4.0.137

Former-commit-id: 943baa9f16a098c33e129777827f3a9d20da00d6

mcs/class/System.Private.CoreLib/System.Threading/Mutex.Unix.cs

@@ -0,0 +1,68 @@
+using System.Runtime.CompilerServices;
+using System.IO;
+
+namespace System.Threading
+{
+	partial class Mutex
+	{
+		Mutex (IntPtr handle) => Handle = handle;
+
+		public void ReleaseMutex ()
+		{
+			if (!ReleaseMutex_internal (Handle))
+				throw new ApplicationException (SR.Arg_SynchronizationLockException);
+		}
+
+		void CreateMutexCore (bool initiallyOwned, string name, out bool createdNew) =>
+			Handle = CreateMutex_internal (initiallyOwned, name, out createdNew);
+
+		unsafe static IntPtr CreateMutex_internal (bool initiallyOwned, string name, out bool created)
+		{
+			fixed (char *fixed_name = name)
+				return CreateMutex_icall (initiallyOwned, fixed_name,
+					name?.Length ?? 0, out created);
+		}
+
+		static OpenExistingResult OpenExistingWorker (string name, out Mutex result) 
+		{
+			if (name == null)
+				throw new ArgumentNullException (nameof (name));
+
+			result = null;
+			if ((name.Length == 0) ||
+				(name.Length > 260)) {
+				return OpenExistingResult.NameInvalid;
+			}
+			
+			MonoIOError error;
+			IntPtr handle = OpenMutex_internal (name, out error);
+			if (handle == IntPtr.Zero) {
+				if (error == MonoIOError.ERROR_FILE_NOT_FOUND) {
+					return OpenExistingResult.NameNotFound;
+				} else if (error == MonoIOError.ERROR_ACCESS_DENIED) {
+					throw new UnauthorizedAccessException ();
+				} else {
+					return OpenExistingResult.PathNotFound;
+				}
+			}
+			
+			result = new Mutex (handle);
+			return OpenExistingResult.Success;
+		}
+
+		unsafe static IntPtr OpenMutex_internal (string name, out MonoIOError error)
+		{
+			fixed (char *fixed_name = name)
+				return OpenMutex_icall (fixed_name, name?.Length ?? 0, 0x000001 /* MutexRights.Modify */, out error);
+		}
+
+		[MethodImplAttribute(MethodImplOptions.InternalCall)]
+		private unsafe static extern IntPtr CreateMutex_icall (bool initiallyOwned, char *name, int name_length, out bool created);
+
+		[MethodImplAttribute(MethodImplOptions.InternalCall)]
+		private unsafe static extern IntPtr OpenMutex_icall (char *name, int name_length, int rights, out MonoIOError error);
+
+		[MethodImplAttribute(MethodImplOptions.InternalCall)]
+		private static extern bool ReleaseMutex_internal (IntPtr handle);
+	}
+}