process: Send signal name to signal handlers

PR-URL: nodejs#15606
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Bartosz Sosnowski <bartosz@janeasystems.com>

doc/api/process.md

@@ -349,6 +349,9 @@ Signal events will be emitted when the Node.js process receives a signal. Please
 refer to signal(7) for a listing of standard POSIX signal names such as
 `SIGINT`, `SIGHUP`, etc.
 
+The signal handler will receive the signal's name (`'SIGINT'`,
+ `'SIGTERM'`, etc.) as the first argument.
+
 The name of each event will be the uppercase common name for the signal (e.g.
 `'SIGINT'` for `SIGINT` signals).
 
@@ -361,6 +364,14 @@ process.stdin.resume();
 process.on('SIGINT', () => {
   console.log('Received SIGINT. Press Control-D to exit.');
 });
+
+// Using a single function to handle multiple signals
+function handle(signal) {
+  console.log(`Received ${signal}`);
+}
+
+process.on('SIGINT', handle);
+process.on('SIGTERM', handle);
 ```
 
 * `SIGUSR1` is reserved by Node.js to start the [debugger][]. It's possible to

lib/internal/process.js

@@ -201,7 +201,7 @@ function setupSignalHandlers() {
 
       wrap.unref();
 
-      wrap.onsignal = function() { process.emit(type); };
+      wrap.onsignal = function() { process.emit(type, type); };
 
       const signum = constants[type];
       const err = wrap.start(signum);

test/parallel/test-signal-args.js

@@ -0,0 +1,24 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+
+if (common.isWindows) {
+  common.skip('Sending signals with process.kill is not supported on Windows');
+}
+
+process.once('SIGINT', common.mustCall((signal) => {
+  assert.strictEqual(signal, 'SIGINT');
+}));
+
+process.kill(process.pid, 'SIGINT');
+
+process.once('SIGTERM', common.mustCall((signal) => {
+  assert.strictEqual(signal, 'SIGTERM');
+}));
+
+process.kill(process.pid, 'SIGTERM');
+
+// Prevent Node.js from exiting due to empty event loop before signal handlers
+// are fired
+setImmediate(() => {});