The newly-created pipe handles won’t be inherited to the child process.To test it out, I created two console applications, PipeServer and PipeClient, using the following snippets
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static class Program { static void Main(string[] args) { var pipe1 = new AnonymousPipeServerStream(PipeDirection.Out, HandleInheritability.Inheritable); var pipe2 = new AnonymousPipeServerStream(PipeDirection.Out, HandleInheritability.Inheritable); using (var proc = Process.Start(new ProcessStartInfo("dotnet", $"\"{typeof(ClientProgram).Assembly.Location}\"") { RedirectStandardInput = true, RedirectStandardOutput = true })) { proc.StandardInput.WriteLine(pipe1.GetClientHandleAsString()); WriteString(pipe1, "Pipe1"); pipe1.Close(); Console.WriteLine(proc.StandardOutput.ReadLine()); proc.StandardInput.WriteLine(pipe2.GetClientHandleAsString()); WriteString(pipe2, "Pipe2"); pipe2.Close(); Console.WriteLine(proc.StandardOutput.ReadLine()); var pipe3 = new AnonymousPipeServerStream(PipeDirection.Out, HandleInheritability.Inheritable); proc.StandardInput.WriteLine(pipe3.GetClientHandleAsString()); WriteString(pipe3, "Pipe3"); pipe3.Close(); Console.WriteLine(proc.StandardOutput.ReadLine()); } } private static void WriteString(Stream s, string content) { var buffer = Encoding.ASCII.GetBytes(content); s.Write(buffer, 0, buffer.Length); s.Flush(); } } |
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public static class ClientProgram { static void Main(string[] args) { while (true) { var handle = Console.ReadLine(); using (var pipe = new AnonymousPipeClientStream(PipeDirection.In, handle)) using (var reader = new StreamReader(pipe, Encoding.ASCII)) { var content = reader.ReadLine(); Console.WriteLine(content); } } } } |
Test the code with VS 2017 + .NET Core 2.0; the result is as follows
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Pipe1 Pipe2 Unhandled Exception: System.IO.IOException: Invalid pipe handle. at System.IO.Pipes.PipeStream.ValidateHandleIsPipe(SafePipeHandle safePipeHandle) at System.IO.Pipes.AnonymousPipeClientStream.Init(PipeDirection direction, SafePipeHandle safePipeHandle) at System.IO.Pipes.AnonymousPipeClientStream..ctor(PipeDirection direction, String pipeHandleAsString) at PipeClient.ClientProgram.Main(String[] args) in \PipeTest\PipeClient\Program.cs:line 16 Press any key to continue... |
Thus, if you want to set up any pipes AFTER the start-up of the children processes, you may consider the name pipes.