child_process: keep SIGWINCH from killing on Win

doc/api/child_process.md

@@ -1714,10 +1714,14 @@ may not actually terminate the process.
 
 See kill(2) for reference.
 
-On Windows, where POSIX signals do not exist, the `signal` argument will be
-ignored except for `'SIGKILL'`, `'SIGTERM'`, `'SIGINT'` and `'SIGQUIT'`, and the
-process will always be killed forcefully and abruptly (similar to `'SIGKILL'`).
-See [Signal Events][] for more details.
+On Windows, where POSIX signals do not exist, signals are handled as follows.
+`'SIGKILL'`, `'SIGTERM'`, `'SIGINT'` and `'SIGQUIT'` terminate the process
+forcefully and abruptly (similar to `'SIGKILL'`); any other signal whose name is
+known on Windows (such as `'SIGHUP'`) does the same. `'SIGWINCH'` is not
+terminal and is not coerced: `subprocess.kill()` throws an `ENOSYS` error and
+the child keeps running. A signal name that does not exist on Windows (such as
+`'SIGSTOP'`) throws an `ERR_UNKNOWN_SIGNAL` error. See [Signal Events][] for more
+details.
 
 On Linux, child processes of child processes will not be terminated
 when attempting to kill their parent. This is likely to happen when running a

src/process_wrap.cc

@@ -351,7 +351,7 @@ class ProcessWrap : public HandleWrap {
     }
 #ifdef _WIN32
     if (signal != SIGKILL && signal != SIGTERM && signal != SIGINT &&
-        signal != SIGQUIT && signal != 0) {
+        signal != SIGQUIT && signal != 0 && signal != SIGWINCH) {
       signal = SIGKILL;
     }
 #endif

test/parallel/test-child-process-kill-sigwinch.js

@@ -0,0 +1,34 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { spawn } = require('child_process');
+
+// SIGWINCH is a non-terminal signal: sending it must not terminate the target
+// process. On Windows, kill() must surface ENOSYS instead of coercing
+// SIGWINCH into a SIGKILL (which would wrongly terminate the process).
+// Refs: https://github.com/nodejs/node/issues/64324
+
+const child = spawn(process.execPath, ['-e', 'setInterval(() => {}, 1000)']);
+
+// The process must survive the SIGWINCH; it is only ever torn down by the
+// explicit SIGKILL in the cleanup below (after the listener is removed).
+child.on('exit', common.mustNotCall('child must survive SIGWINCH'));
+
+child.on('spawn', common.mustCall(() => {
+  if (common.isWindows) {
+    assert.throws(() => child.kill('SIGWINCH'), { code: 'ENOSYS' });
+  } else {
+    assert.strictEqual(child.kill('SIGWINCH'), true);
+  }
+
+  assert.strictEqual(child.signalCode, null);
+  assert.strictEqual(child.exitCode, null);
+
+  setTimeout(common.mustCall(() => {
+    assert.strictEqual(child.signalCode, null);
+    assert.strictEqual(child.exitCode, null);
+
+    child.removeAllListeners('exit');
+    child.kill('SIGKILL');
+  }), common.platformTimeout(500));
+}));