Implemented Ctrl+C functionality for cancelling spawned child processes

Author: cppshane

Background-Terminal/Background-Terminal.csproj

@@ -20,6 +20,7 @@
     <PackageReference Include="CoreMeter" Version="1.0.2" />
     <PackageReference Include="Hardcodet.NotifyIcon.Wpf.NetCore" Version="1.0.10" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
+    <PackageReference Include="System.Management" Version="4.7.0" />
   </ItemGroup>
 
   <ItemGroup>

Background-Terminal/MainWindow.xaml.cs

@@ -6,6 +6,7 @@
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Management;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
@@ -35,10 +36,12 @@ public partial class MainWindow : Window
 
         private BackgroundTerminalSettings _settings;
 
-        private Process _cmdProcess;
+        private Process _process;
 
         private ObservableCollection<string> _terminalData = new ObservableCollection<string>();
 
+        private int _cmdProcessId;
+
         private bool _terminalWindowActive = false;
 
         private bool _awaitingKey1 = false;
@@ -52,7 +55,7 @@ public MainWindow()
             InitializeComponent();
 
             // Create TerminalWindow
-            _terminalWindow = new TerminalWindow(SendCommand);
+            _terminalWindow = new TerminalWindow(SendCommand, KillChildren);
             _terminalWindow.Show();
 
             // Apply changes in terminal data to TerminalWindow
@@ -136,34 +139,51 @@ private void ApplySettingsToTerminalWindow()
             _terminalWindow.UpdateTerminalDataTextBoxMargin();
         }
 
+        private List<Process> GetProcessChildren()
+        {
+            List<Process> children = new List<Process>();
+            ManagementObjectSearcher managementObjectSearcher = new ManagementObjectSearcher(String.Format("Select * From Win32_Process Where ParentProcessID={0}", _process.Id));
+
+            foreach (ManagementObject managementObject in managementObjectSearcher.Get())
+            {
+                children.Add(Process.GetProcessById(Convert.ToInt32(managementObject["ProcessID"])));
+            }
+
+            return children;
+        }
+
         #region Terminal Data Handlers
         private async Task<int> RunTerminalProcessAsync()
         {
             TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>();
 
-            _cmdProcess = new Process();
+            _process = new Process();
 
-            _cmdProcess.StartInfo.FileName = "cmd.exe";
-            _cmdProcess.StartInfo.WorkingDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
-            _cmdProcess.StartInfo.UseShellExecute = false;
-            _cmdProcess.StartInfo.CreateNoWindow = true;
-            _cmdProcess.StartInfo.RedirectStandardInput = true;
-            _cmdProcess.StartInfo.RedirectStandardOutput = true;
-            _cmdProcess.StartInfo.RedirectStandardError = true;
+            _process.StartInfo.FileName = "cmd.exe";
+            _process.StartInfo.WorkingDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
+            _process.StartInfo.UseShellExecute = false;
+            _process.StartInfo.CreateNoWindow = true;
+            _process.StartInfo.RedirectStandardInput = true;
+            _process.StartInfo.RedirectStandardOutput = true;
+            _process.StartInfo.RedirectStandardError = true;
 
-            _cmdProcess.EnableRaisingEvents = true;
-            _cmdProcess.OutputDataReceived += CMD_OutputDataReceived;
-            _cmdProcess.ErrorDataReceived += CMD_ErrorDataReceived;
+            _process.EnableRaisingEvents = true;
+            _process.OutputDataReceived += CMD_OutputDataReceived;
+            _process.ErrorDataReceived += CMD_ErrorDataReceived;
 
-            _cmdProcess.Exited += new EventHandler((sender, args) =>
+            _process.Exited += new EventHandler((sender, args) =>
             {
-                taskCompletionSource.SetResult(_cmdProcess.ExitCode);
-                _cmdProcess.Dispose();
+                taskCompletionSource.SetResult(_process.ExitCode);
+                _process.Dispose();
             });
 
-            _cmdProcess.Start();
-            _cmdProcess.BeginOutputReadLine();
-            _cmdProcess.BeginErrorReadLine();
+            _process.Start();
+            _process.BeginOutputReadLine();
+            _process.BeginErrorReadLine();
+
+            List<Process> children = GetProcessChildren();
+            if (children.Count > 0)
+                _cmdProcessId = children[0].Id;
 
             return await taskCompletionSource.Task;
         }
@@ -178,10 +198,25 @@ private void CMD_ErrorDataReceived(object sender, DataReceivedEventArgs e)
             _terminalData.Add(e.Data);
         }
 
-        private void SendCommand(string command)
+        private void SendCommand(string command, bool output = true)
         {
-            _terminalData.Add(command);
-            _cmdProcess.StandardInput.WriteLine(command);
+            if (output)
+                _terminalData.Add(command);
+
+            _process.StandardInput.WriteLine(command);
+        }
+
+        private void KillChildren()
+        {
+            List<Process> children = GetProcessChildren();
+
+            foreach (Process child in children)
+            {
+                if (!child.Id.Equals(_cmdProcessId))
+                {
+                    child.Kill();
+                }
+            }
         }
         #endregion
 

Background-Terminal/TerminalWindow.xaml

@@ -29,6 +29,7 @@
             BorderThickness="0"
             Focusable="True"
             FontFamily="Consolas"
-            PreviewKeyDown="InputTextBox_PreviewKeyDown" />
+            PreviewKeyDown="InputTextBox_PreviewKeyDown"
+            PreviewKeyUp="InputTextBox_PreviewKeyUp" />
     </Grid>
 </Window>

Background-Terminal/TerminalWindow.xaml.cs

@@ -14,14 +14,20 @@ namespace Background_Terminal
 {
     public partial class TerminalWindow : Window
     {
-        public delegate void SendCommandProc(string command);
+        public delegate void SendCommandProc(string command, bool output = false);
         private SendCommandProc SendCommand;
 
-        public TerminalWindow(SendCommandProc sendCommand)
+        public delegate void KillChildrenProc();
+        private KillChildrenProc KillChildren;
+
+        bool _ctrlDown = false;
+
+        public TerminalWindow(SendCommandProc sendCommand, KillChildrenProc killChildren)
         {
             InitializeComponent();
 
             SendCommand = sendCommand;
+            KillChildren = killChildren;
         }
 
         public void UpdateTerminalDataTextBoxMargin() // I do what I want
@@ -30,13 +36,26 @@ public TerminalWindow(SendCommandProc sendCommand)
         }
 
         #region Event Handlers
-        public void TerminalDataTextBox_TextChanged(object sender, TextChangedEventArgs e)
+        private void TerminalDataTextBox_TextChanged(object sender, TextChangedEventArgs e)
         {
             TerminalData_TextBox.ScrollToEnd();
         }
 
-        public void InputTextBox_PreviewKeyDown(object sender, KeyEventArgs e)
+        private void InputTextBox_PreviewKeyDown(object sender, KeyEventArgs e)
         {
+            // Cancel current command
+            if (e.Key.Equals(Key.C) && _ctrlDown)
+            {
+                KillChildren();
+
+                e.Handled = true;
+            }
+
+            if (e.Key.Equals(Key.LeftCtrl))
+            {
+                _ctrlDown = true;
+            }
+
             if (e.Key.Equals(Key.Return) || e.Key.Equals(Key.Enter))
             {
                 SendCommand(Input_TextBox.Text);
@@ -45,7 +64,15 @@ public void InputTextBox_PreviewKeyDown(object sender, KeyEventArgs e)
             }
         }
 
-        public void TerminalWindow_Loaded(object sender, EventArgs e)
+        private void InputTextBox_PreviewKeyUp(object sender, KeyEventArgs e)
+        {
+            if (e.Key.Equals(Key.LeftCtrl))
+            {
+                _ctrlDown = false;
+            }
+        }
+
+        private void TerminalWindow_Loaded(object sender, EventArgs e)
         {
             UpdateTerminalDataTextBoxMargin();
         }