feat: add safe command termination (#1012)

Author: aikawayataro

src/Commands/Command.cs

@@ -37,6 +37,12 @@ public enum EditorType
         public string Args { get; set; } = string.Empty;
         public bool RaiseError { get; set; } = true;
         public bool TraitErrorAsOutput { get; set; } = false;
+        public bool Cancelable { get; } = false;
+
+        public Command(bool cancelable = false)
+        {
+            Cancelable = cancelable;
+        }
 
         public bool Exec()
         {
@@ -109,12 +115,22 @@ public bool Exec()
                 return false;
             }
 
-            proc.BeginOutputReadLine();
-            proc.BeginErrorReadLine();
-            proc.WaitForExit();
+            _proc = proc;
+
+            int exitCode;
+            try
+            {
+                proc.BeginOutputReadLine();
+                proc.BeginErrorReadLine();
+                proc.WaitForExit();
 
-            int exitCode = proc.ExitCode;
-            proc.Close();
+                exitCode = proc.ExitCode;
+                proc.Close();
+            }
+            finally
+            {
+                _proc = null;
+            }
 
             if (!isCancelled && exitCode != 0)
             {
@@ -150,17 +166,37 @@ public ReadToEndResult ReadToEnd()
                 };
             }
 
-            var rs = new ReadToEndResult()
+            _proc = proc;
+
+            try
             {
-                StdOut = proc.StandardOutput.ReadToEnd(),
-                StdErr = proc.StandardError.ReadToEnd(),
-            };
+                var rs = new ReadToEndResult()
+                {
+                    StdOut = proc.StandardOutput.ReadToEnd(),
+                    StdErr = proc.StandardError.ReadToEnd(),
+                };
 
-            proc.WaitForExit();
-            rs.IsSuccess = proc.ExitCode == 0;
-            proc.Close();
+                proc.WaitForExit();
+                rs.IsSuccess = proc.ExitCode == 0;
+                proc.Close();
 
-            return rs;
+                return rs;
+            }
+            finally
+            {
+                _proc = null;
+            }
+        }
+
+        public void TryCancel()
+        {
+            if (!this.Cancelable)
+                throw new Exception("Command is not cancelable!");
+
+            if (_proc is null)
+                return;
+
+            Native.OS.TerminateSafely(_proc);
         }
 
         protected virtual void OnReadline(string line)
@@ -226,5 +262,7 @@ private ProcessStartInfo CreateGitStartInfo()
 
         [GeneratedRegex(@"\d+%")]
         private static partial Regex REG_PROGRESS();
+
+        private Process _proc = null;
     }
 }

src/Native/Linux.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 
 using Avalonia;
@@ -11,6 +12,14 @@ namespace SourceGit.Native
     [SupportedOSPlatform("linux")]
     internal class Linux : OS.IBackend
     {
+        private enum SIGNAL : int
+        {
+            TERM = 15
+        }
+
+        [DllImport("c")]
+        private static extern int kill(int pid, int sig);
+
         public void SetupApp(AppBuilder builder)
         {
             builder.With(new X11PlatformOptions() { EnableIme = true });
@@ -97,6 +106,12 @@ public void OpenWithDefaultEditor(string file)
             }
         }
 
+        public void TerminateSafely(Process process)
+        {
+            if (kill(process.Id, (int)SIGNAL.TERM) == 0)
+                process.WaitForExit();
+        }
+
         private string FindExecutable(string filename)
         {
             var pathVariable = Environment.GetEnvironmentVariable("PATH") ?? string.Empty;

src/Native/MacOS.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 
 using Avalonia;
@@ -11,6 +12,14 @@ namespace SourceGit.Native
     [SupportedOSPlatform("macOS")]
     internal class MacOS : OS.IBackend
     {
+        private enum SIGNAL : int
+        {
+            TERM = 15
+        }
+
+        [DllImport("System")]
+        private static extern int kill(int pid, int sig);
+
         public void SetupApp(AppBuilder builder)
         {
             builder.With(new MacOSPlatformOptions()
@@ -88,5 +97,11 @@ public void OpenWithDefaultEditor(string file)
         {
             Process.Start("open", $"\"{file}\"");
         }
+
+        public void TerminateSafely(Process process)
+        {
+            if (kill(process.Id, (int)SIGNAL.TERM) == 0)
+                process.WaitForExit();
+        }
     }
 }

src/Native/OS.cs

@@ -23,6 +23,8 @@ public interface IBackend
             void OpenInFileManager(string path, bool select);
             void OpenBrowser(string url);
             void OpenWithDefaultEditor(string file);
+
+            void TerminateSafely(Process process);
         }
 
         public static string DataDir
@@ -168,6 +170,11 @@ public static void OpenWithDefaultEditor(string file)
             _backend.OpenWithDefaultEditor(file);
         }
 
+        public static void TerminateSafely(Process process)
+        {
+            _backend.TerminateSafely(process);
+        }
+
         private static void UpdateGitVersion()
         {
             if (string.IsNullOrEmpty(_gitExecutable) || !File.Exists(_gitExecutable))

src/Native/Windows.cs

@@ -35,6 +35,11 @@ internal struct MARGINS
             public int cyBottomHeight;
         }
 
+        private enum CTRL_EVENT : int
+        {
+            CTRL_C = 0
+        }
+
         [DllImport("ntdll.dll")]
         private static extern int RtlGetVersion(ref RTL_OSVERSIONINFOEX lpVersionInformation);
 
@@ -53,6 +58,12 @@ internal struct MARGINS
         [DllImport("shell32.dll", CharSet = CharSet.Unicode, SetLastError = false)]
         private static extern int SHOpenFolderAndSelectItems(IntPtr pidlFolder, int cild, IntPtr apidl, int dwFlags);
 
+        [DllImport("kernel32.dll")]
+        public static extern bool SetConsoleCtrlHandler(IntPtr handlerRoutine, bool add);
+
+        [DllImport("kernel32.dll")]
+        private static extern bool GenerateConsoleCtrlEvent(int dwCtrlEvent, int dwProcessGroupId);
+
         public void SetupApp(AppBuilder builder)
         {
             // Fix drop shadow issue on Windows 10
@@ -212,6 +223,22 @@ public void OpenWithDefaultEditor(string file)
             Process.Start(start);
         }
 
+        public void TerminateSafely(Process process)
+        {
+            if (SetConsoleCtrlHandler(IntPtr.Zero, true))
+            {
+                try
+                {
+                    if (GenerateConsoleCtrlEvent((int)CTRL_EVENT.CTRL_C, process.Id))
+                        process.WaitForExit();
+                }
+                finally
+                {
+                    SetConsoleCtrlHandler(IntPtr.Zero, false);
+                }
+            }
+        }
+
         private void FixWindowFrameOnWin10(Window w)
         {
             var platformHandle = w.TryGetPlatformHandle();