fix: add support for SIGINT on Windows (fixes issue #1720) (#1853)

Smashing work by @countzero ❤️

lib/monitor/run.js

@@ -5,6 +5,7 @@ var bus = utils.bus;
 var childProcess = require('child_process');
 var spawn = childProcess.spawn;
 var exec = childProcess.exec;
+var execSync = childProcess.execSync;
 var fork = childProcess.fork;
 var watch = require('./watch').watch;
 var config = require('../config');
@@ -305,20 +306,62 @@ function waitForSubProcesses(pid, callback) {
 }
 
 function kill(child, signal, callback) {
+
   if (!callback) {
-    callback = function () { };
+    callback = noop;
   }
 
   if (utils.isWindows) {
-    // When using CoffeeScript under Windows, child's process is not node.exe
-    // Instead coffee.cmd is launched, which launches cmd.exe, which starts
-    // node.exe as a child process child.kill() would only kill cmd.exe, not
-    // node.exe
-    // Therefore we use the Windows taskkill utility to kill the process and all
-    // its children (/T for tree).
-    // Force kill (/F) the whole child tree (/T) by PID (/PID 123)
-    exec('taskkill /pid ' + child.pid + ' /T /F');
+
+    // We are handling a 'SIGKILL' POSIX signal under Windows the
+    // same way it is handled on a UNIX system: We are performing
+    // a hard shutdown without waiting for the process to clean-up.
+    if (signal === 'SIGKILL') {
+
+      debug('terminating process group by force: %s', child.pid);
+
+      // We are using the taskkill utility to terminate the whole
+      // process group ('/t') of the child ('/pid') by force ('/f').
+      // We need to end all sub processes, because the 'child'
+      // process in this context is actually a cmd.exe wrapper.
+      exec(`taskkill /f /t /pid ${child.pid}`);
+      callback();
+      return;
+    }
+
+    // We are using the Windows Management Instrumentation Command-line
+    // (wmic.exe) to resolve the sub-child process identifier, because the
+    // 'child' process in this context is actually a cmd.exe wrapper.
+    // We want to send the termination signal directly to the node process.
+    // The '2> nul' silences the no process found error message.
+    const resultBuffer = execSync(
+      `wmic process where (ParentProcessId=${child.pid}) get ProcessId 2> nul`
+    );
+    const result = resultBuffer.toString().match(/^[0-9]+/m);
+
+    // If there is no sub-child process we fall back to the child process.
+    const processId = Array.isArray(result) ? result[0] : child.pid;
+
+    debug('sending kill signal SIGINT to process: %s', processId);
+
+    // We are using the standalone 'windows-kill' executable to send the
+    // standard POSIX signal 'SIGINT' to the node process. This fixes #1720.
+    const windowsKill = path.normalize(
+      `${process.cwd()}/node_modules/nodemon/bin/windows-kill.exe`
+    );
+
+    // We have to detach the 'windows-kill' execution completely from this
+    // process group to avoid terminating the nodemon process itself.
+    // See: https://github.com/alirdn/windows-kill#how-it-works--limitations
+    //
+    // Therefore we are using 'start' to create a new cmd.exe context.
+    // The '/min' option hides the new terminal window and the '/wait'
+    // option lets the process wait for the command to finish.
+    execSync(
+      `start "windows-kill" /min /wait "${windowsKill}" -SIGINT ${processId}`
+    );
     callback();
+
   } else {
     // we use psTree to kill the full subtree of nodemon, because when
     // spawning processes like `coffee` under the `--debug` flag, it'll spawn