node: delete NODE_CHANNEL_FD from env

Prevents accidental inheritance by child processes. If the child process is a
node process, it would try to set up a channel with the parent and consequently
never quit because the channel kept the event loop alive.

Fixes #3240.

src/node.js

@@ -415,6 +415,10 @@
     // start parsing data from that stream.
     if (process.env.NODE_CHANNEL_FD) {
       assert(parseInt(process.env.NODE_CHANNEL_FD) >= 0);
+
+      // Make sure it's not accidentally inherited by child processes.
+      delete process.env.NODE_CHANNEL_FD;
+
       var cp = NativeModule.require('child_process');
 
       // Load tcp_wrap to avoid situation where we might immediately receive

test/simple/test-child-process-fork-and-spawn.js

@@ -0,0 +1,53 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var spawn = require('child_process').spawn;
+var fork = require('child_process').fork;
+
+// Fork, then spawn. The spawned process should not hang.
+switch (process.argv[2] || '') {
+case '':
+  fork(__filename, ['fork']).on('exit', checkExit);
+  process.on('exit', haveExit);
+  break;
+case 'fork':
+  spawn(process.execPath, [__filename, 'spawn']).on('exit', checkExit);
+  process.on('exit', haveExit);
+  break;
+case 'spawn':
+  break;
+default:
+  assert(0);
+}
+
+var seenExit = false;
+
+function checkExit(statusCode) {
+  seenExit = true;
+  assert.equal(statusCode, 0);
+  process.nextTick(process.exit);
+}
+
+function haveExit() {
+  assert.equal(seenExit, true);
+}