Add PipeOptions.FirstPipeInstance enum value

src/libraries/System.IO.Pipes/ref/System.IO.Pipes.cs

@@ -95,6 +95,7 @@ public enum PipeOptions
         None = 0,
         CurrentUserOnly = 536870912,
         Asynchronous = 1073741824,
+        FirstPipeInstance = 524288
     }
     public abstract partial class PipeStream : System.IO.Stream
     {

src/libraries/System.IO.Pipes/src/Resources/Strings.resx

@@ -243,6 +243,9 @@
   <data name="PlatformNotSupported_MessageTransmissionMode" xml:space="preserve">
     <value>Message transmission mode is not supported on this platform.</value>
   </data>
+  <data name="PlatformNotSupported_PipeOptions_FirstPipeInstance" xml:space="preserve">
+    <value>First Pipe Instance option is not supported on this platform.</value>
+  </data>
   <data name="PlatformNotSupported_RemotePipes" xml:space="preserve">
     <value>Access to remote named pipes is not supported on this platform.</value>
   </data>

src/libraries/System.IO.Pipes/src/System/IO/Pipes/NamedPipeServerStream.Unix.cs

@@ -38,6 +38,11 @@ private void Create(string pipeName, PipeDirection direction, int maxNumberOfSer
                 throw new PlatformNotSupportedException(SR.PlatformNotSupported_MessageTransmissionMode);
             }
 
+            if ((options & PipeOptions.FirstPipeInstance) != 0)
+            {
+                throw new PlatformNotSupportedException(SR.PlatformNotSupported_PipeOptions_FirstPipeInstance);
+            }
+
             // We don't have a good way to enforce maxNumberOfServerInstances across processes; we only factor it in
             // for streams created in this process.  Between processes, we behave similarly to maxNumberOfServerInstances == 1,
             // in that the second process to come along and create a stream will find the pipe already in existence and will fail.

src/libraries/System.IO.Pipes/src/System/IO/Pipes/NamedPipeServerStream.cs

@@ -60,10 +60,10 @@ public NamedPipeServerStream(string pipeName, PipeDirection direction, int maxNu
         /// Win32 note: this gets used for dwPipeMode. CreateNamedPipe allows you to specify PIPE_TYPE_BYTE/MESSAGE
         /// and PIPE_READMODE_BYTE/MESSAGE independently, but this sets type and readmode to match.
         /// </param>
-        /// <param name="options">PipeOption enum: None, Asynchronous, or Write-through
+        /// <param name="options">PipeOption enum: None, Asynchronous, or Write-through or FirstPipeInstance
         /// Win32 note: this gets passed in with dwOpenMode to CreateNamedPipe. Asynchronous corresponds to
-        /// FILE_FLAG_OVERLAPPED option. PipeOptions enum doesn't expose FIRST_PIPE_INSTANCE option because
-        /// this sets that automatically based on the number of instances specified.
+        /// FILE_FLAG_OVERLAPPED option. PipeOptions.FIRST_PIPE_INSTANCE
+        /// is automatically set based on the number of instances specified.
         /// </param>
         /// <param name="inBufferSize">Incoming buffer size, 0 or higher.
         /// Note: this size is always advisory; OS uses a suggestion.
@@ -103,7 +103,7 @@ private void ValidateParameters(
             {
                 throw new ArgumentOutOfRangeException(nameof(transmissionMode), SR.ArgumentOutOfRange_TransmissionModeByteOrMsg);
             }
-            if ((options & ~(PipeOptions.WriteThrough | PipeOptions.Asynchronous | PipeOptions.CurrentUserOnly)) != 0)
+            if ((options & ~(PipeOptions.WriteThrough | PipeOptions.Asynchronous | PipeOptions.CurrentUserOnly | PipeOptions.FirstPipeInstance)) != 0)
             {
                 throw new ArgumentOutOfRangeException(nameof(options), SR.ArgumentOutOfRange_OptionsInvalid);
             }

src/libraries/System.IO.Pipes/src/System/IO/Pipes/PipeOptions.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Runtime.Versioning;
+
 namespace System.IO.Pipes
 {
     [Flags]
@@ -9,6 +11,7 @@ public enum PipeOptions
         None = 0x0,
         WriteThrough = unchecked((int)0x80000000),
         Asynchronous = unchecked((int)0x40000000),  // corresponds to FILE_FLAG_OVERLAPPED
-        CurrentUserOnly = unchecked((int)0x20000000)
+        CurrentUserOnly = unchecked((int)0x20000000),
+        FirstPipeInstance = unchecked((int)0x00080000)
     }
 }

src/libraries/System.IO.Pipes/tests/NamedPipeTests/NamedPipeTest.CreateServer.cs

@@ -52,7 +52,8 @@ public static void ReservedPipeName_Throws_ArgumentOutOfRangeException(PipeDirec
             AssertExtensions.Throws<ArgumentOutOfRangeException>("pipeName", () => new NamedPipeServerStream(reservedName, direction, 1));
             AssertExtensions.Throws<ArgumentOutOfRangeException>("pipeName", () => new NamedPipeServerStream(reservedName, direction, 1, PipeTransmissionMode.Byte));
             AssertExtensions.Throws<ArgumentOutOfRangeException>("pipeName", () => new NamedPipeServerStream(reservedName, direction, 1, PipeTransmissionMode.Byte, PipeOptions.None));
-            AssertExtensions.Throws<ArgumentOutOfRangeException>("pipeName", () => new NamedPipeServerStream(reservedName, direction, 1, PipeTransmissionMode.Byte, PipeOptions.None, 0, 0));}
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("pipeName", () => new NamedPipeServerStream(reservedName, direction, 1, PipeTransmissionMode.Byte, PipeOptions.None, 0, 0));
+        }
 
         [Fact]
         [SkipOnPlatform(TestPlatforms.LinuxBionic, "SElinux blocks UNIX sockets in our CI environment")]
@@ -254,5 +255,12 @@ public static void Windows_ServerCloneWithDifferentDirection_Throws_Unauthorized
                 Assert.Throws<UnauthorizedAccessException>(() => new NamedPipeServerStream(uniqueServerName, PipeDirection.Out));
             }
         }
+
+        [Fact]
+        [PlatformSpecific(TestPlatforms.AnyUnix)]
+        public static void Unix_PipeOptions_FirstPipeInstance_ThrowsPlatformNotSupportedException()
+        {
+            Assert.Throws<PlatformNotSupportedException>(() => new NamedPipeServerStream(PipeStreamConformanceTests.GetUniquePipeName(), PipeDirection.Out, 1, PipeTransmissionMode.Byte, PipeOptions.FirstPipeInstance));
+        }
     }
 }