Re-implement legacy readline support

src/PowerShellEditorServices/Services/PowerShell/Console/IReadLine.cs

@@ -12,9 +12,5 @@ internal interface IReadLine
         string ReadLine(CancellationToken cancellationToken);
 
         SecureString ReadSecureLine(CancellationToken cancellationToken);
-
-        bool TryOverrideReadKey(Func<bool, ConsoleKeyInfo> readKeyOverride);
-
-        bool TryOverrideIdleHandler(Action<CancellationToken> idleHandler);
     }
 }

src/PowerShellEditorServices/Services/PowerShell/Console/PsrlReadLine.cs

@@ -0,0 +1,63 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Microsoft.PowerShell.EditorServices.Services.PowerShell.Execution;
+using Microsoft.PowerShell.EditorServices.Services.PowerShell.Host;
+using System.Management.Automation;
+using System.Threading;
+
+namespace Microsoft.PowerShell.EditorServices.Services.PowerShell.Console
+{
+    using System;
+
+    internal class PsrlReadLine : TerminalReadLine
+    {
+        private readonly PSReadLineProxy _psrlProxy;
+
+        private readonly PsesInternalHost _psesHost;
+
+        private readonly EngineIntrinsics _engineIntrinsics;
+
+        #region Constructors
+
+        public PsrlReadLine(
+            PSReadLineProxy psrlProxy,
+            PsesInternalHost psesHost,
+            EngineIntrinsics engineIntrinsics,
+            Func<bool, ConsoleKeyInfo> readKeyFunc,
+            Action<CancellationToken> onIdleAction)
+        {
+            _psrlProxy = psrlProxy;
+            _psesHost = psesHost;
+            _engineIntrinsics = engineIntrinsics;
+            _psrlProxy.OverrideReadKey(readKeyFunc);
+            _psrlProxy.OverrideIdleHandler(onIdleAction);
+        }
+
+        #endregion
+
+        #region Public Methods
+
+        public override string ReadLine(CancellationToken cancellationToken)
+        {
+            return _psesHost.InvokeDelegate<string>(representation: "ReadLine", new ExecutionOptions { MustRunInForeground = true }, InvokePSReadLine, cancellationToken);
+        }
+
+        protected override ConsoleKeyInfo ReadKey(CancellationToken cancellationToken)
+        {
+            return ConsoleProxy.ReadKey(intercept: true, cancellationToken);
+        }
+
+        #endregion
+
+        #region Private Methods
+
+        private string InvokePSReadLine(CancellationToken cancellationToken)
+        {
+            EngineIntrinsics engineIntrinsics = _psesHost.IsRunspacePushed ? null : _engineIntrinsics;
+            return _psrlProxy.ReadLine(_psesHost.Runspace, engineIntrinsics, cancellationToken, /* lastExecutionStatus */ null);
+        }
+
+        #endregion
+    }
+}

src/PowerShellEditorServices/Services/PowerShell/Console/TerminalReadLine.cs

@@ -0,0 +1,99 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.PowerShell.EditorServices.Services.PowerShell.Utility;
+using System.Management.Automation;
+using System.Security;
+using System.Threading;
+
+namespace Microsoft.PowerShell.EditorServices.Services.PowerShell.Console
+{
+    using System;
+
+    internal abstract class TerminalReadLine : IReadLine
+    {
+        public abstract string ReadLine(CancellationToken cancellationToken);
+
+        protected abstract ConsoleKeyInfo ReadKey(CancellationToken cancellationToken);
+
+        public SecureString ReadSecureLine(CancellationToken cancellationToken)
+        {
+            Console.TreatControlCAsInput = true;
+            int previousInputLength = 0;
+            SecureString secureString = new SecureString();
+            try
+            {
+                bool enterPressed = false;
+                while (!enterPressed && !cancellationToken.IsCancellationRequested)
+                {
+                    ConsoleKeyInfo keyInfo = ReadKey(cancellationToken);
+
+                    if (keyInfo.IsCtrlC())
+                    {
+                        throw new PipelineStoppedException();
+                    }
+
+                    switch (keyInfo.Key)
+                    {
+                        case ConsoleKey.Enter:
+                            // Stop the while loop so we can realign the cursor
+                            // and then return the entered string
+                            enterPressed = true;
+                            continue;
+
+                        case ConsoleKey.Tab:
+                            break;
+
+                        case ConsoleKey.Backspace:
+                            if (secureString.Length > 0)
+                            {
+                                secureString.RemoveAt(secureString.Length - 1);
+                            }
+                            break;
+
+                        default:
+                            if (keyInfo.KeyChar != 0 && !char.IsControl(keyInfo.KeyChar))
+                            {
+                                secureString.AppendChar(keyInfo.KeyChar);
+                            }
+                            break;
+                    }
+
+                    // Re-render the secure string characters
+                    int currentInputLength = secureString.Length;
+                    int consoleWidth = Console.WindowWidth;
+
+                    if (currentInputLength > previousInputLength)
+                    {
+                        Console.Write('*');
+                    }
+                    else if (previousInputLength > 0 && currentInputLength < previousInputLength)
+                    {
+                        int row = ConsoleProxy.GetCursorTop(cancellationToken);
+                        int col = ConsoleProxy.GetCursorLeft(cancellationToken);
+
+                        // Back up the cursor before clearing the character
+                        col--;
+                        if (col < 0)
+                        {
+                            col = consoleWidth - 1;
+                            row--;
+                        }
+
+                        Console.SetCursorPosition(col, row);
+                        Console.Write(' ');
+                        Console.SetCursorPosition(col, row);
+                    }
+
+                    previousInputLength = currentInputLength;
+                }
+            }
+            finally
+            {
+                Console.TreatControlCAsInput = false;
+            }
+
+            return secureString;
+        }
+    }
+}

src/PowerShellEditorServices/Services/PowerShell/Host/PsesInternalHost.cs

@@ -625,12 +625,14 @@ private static PowerShell CreatePowerShellForRunspace(Runspace runspace)
 
             var engineIntrinsics = (EngineIntrinsics)runspace.SessionStateProxy.GetVariable("ExecutionContext");
 
-            if (hostStartupInfo.ConsoleReplEnabled && !hostStartupInfo.UsesLegacyReadLine)
+            if (hostStartupInfo.ConsoleReplEnabled)
             {
-                var psrlProxy = PSReadLineProxy.LoadAndCreate(_loggerFactory, pwsh);
-                var readLine = new ConsoleReadLine(psrlProxy, this, engineIntrinsics);
-                readLine.TryOverrideReadKey(ReadKey);
-                readLine.TryOverrideIdleHandler(OnPowerShellIdle);
+                // If we've been configured to use it, or if we can't load PSReadLine, use the legacy readline
+                if (hostStartupInfo.UsesLegacyReadLine || !TryLoadPSReadLine(pwsh, engineIntrinsics, out IReadLine readLine))
+                {
+                    readLine = new LegacyReadLine(this, ReadKey, OnPowerShellIdle);
+                }
+
                 readLineProvider.OverrideReadLine(readLine);
                 System.Console.CancelKeyPress += OnCancelKeyPress;
                 System.Console.InputEncoding = Encoding.UTF8;
@@ -747,9 +749,7 @@ private ConsoleKeyInfo ReadKey(bool intercept)
         private bool LastKeyWasCtrlC()
         {
             return _lastKey.HasValue
-                && _lastKey.Value.Key == ConsoleKey.C
-                && (_lastKey.Value.Modifiers & ConsoleModifiers.Control) != 0
-                && (_lastKey.Value.Modifiers & ConsoleModifiers.Alt) == 0;
+                && _lastKey.Value.IsCtrlC();
         }
 
         private void OnDebuggerStopped(object sender, DebuggerStopEventArgs debuggerStopEventArgs)
@@ -825,6 +825,22 @@ private Task PopOrReinitializeRunspaceAsync()
                 CancellationToken.None);
         }
 
+        private bool TryLoadPSReadLine(PowerShell pwsh, EngineIntrinsics engineIntrinsics, out IReadLine psrlReadLine)
+        {
+            psrlReadLine = null;
+            try
+            {
+                var psrlProxy = PSReadLineProxy.LoadAndCreate(_loggerFactory, pwsh);
+                psrlReadLine = new PsrlReadLine(psrlProxy, this, engineIntrinsics, ReadKey, OnPowerShellIdle);
+                return true;
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, "Unable to load PSReadLine. Will fall back to legacy readline implementation.");
+                return false;
+            }
+        }
+
         private record RunspaceFrame(
             Runspace Runspace,
             RunspaceInfo RunspaceInfo);

src/PowerShellEditorServices/Services/PowerShell/Utility/ConsoleKeyInfoExtensions.cs

@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+
+namespace Microsoft.PowerShell.EditorServices.Services.PowerShell.Utility
+{
+    internal static class ConsoleKeyInfoExtensions
+    {
+        public static bool IsCtrlC(this ConsoleKeyInfo keyInfo)
+        {
+            if ((int)keyInfo.Key == 3)
+            {
+                return true;
+            }
+
+            return keyInfo.Key == ConsoleKey.C
+                && (keyInfo.Modifiers & ConsoleModifiers.Control) != 0
+                && (keyInfo.Modifiers & ConsoleModifiers.Shift) == 0
+                && (keyInfo.Modifiers & ConsoleModifiers.Alt) == 0;
+        }
+    }
+}