src: don't kill own process group on failed spawn

src/process_wrap.cc

@@ -112,6 +112,7 @@ class ProcessWrap : public HandleWrap {
                    object,
                    reinterpret_cast<uv_handle_t*>(&process_),
                    AsyncWrap::PROVIDER_PROCESSWRAP) {
+    process_.pid = 0;
     MarkAsUninitialized();
   }
 
@@ -355,7 +356,10 @@ class ProcessWrap : public HandleWrap {
       signal = SIGKILL;
     }
 #endif
-    int err = uv_process_kill(&wrap->process_, signal);
+    // uv_spawn() only assigns a pid when it succeeds, and kill(0, signal)
+    // signals every process in our own process group.
+    int err = wrap->process_.pid > 0 ? uv_process_kill(&wrap->process_, signal)
+                                     : UV_ESRCH;
     args.GetReturnValue().Set(err);
   }
 

test/fixtures/child-process-kill-spawn-error.js

@@ -0,0 +1,4 @@
+const { spawn } = require('child_process');
+const child = spawn('foo123');
+child.on('error', () => {});
+if (child.kill() !== false || child.killed !== false) process.exit(1);

test/parallel/test-child-process-kill-spawn-error.js

@@ -0,0 +1,16 @@
+'use strict';
+const common = require('../common');
+const fixtures = require('../common/fixtures');
+const assert = require('assert');
+const { spawn } = require('child_process');
+
+// Killing a child process that never spawned must not signal the process
+// group of the caller. The check runs in a detached child so that a
+// regression cannot take the test runner down with it.
+const childPath = fixtures.path('child-process-kill-spawn-error.js');
+const child = spawn(process.execPath, [childPath], { detached: true });
+
+child.on('exit', common.mustCall((code, signal) => {
+  assert.strictEqual(signal, null);
+  assert.strictEqual(code, 0);
+}));