net: Respect the 'readable' flag on sockets

Previously, we were only destroying sockets on end if their readable
side had already been ended.  This causes a problem for non-readable
streams, since we don't expect to ever see an 'end' event from those.

Treat the lack of a 'readable' flag the same as if it was an ended
readable stream.

Fix #4751

lib/net.js

@@ -184,7 +184,7 @@ util.inherits(Socket, stream.Duplex);
 // so that only the writable side will be cleaned up.
 function onSocketFinish() {
   debug('onSocketFinish');
-  if (this._readableState.ended) {
+  if (!this.readable || this._readableState.ended) {
     debug('oSF: ended, destroy', this._readableState);
     return this.destroy();
   }
@@ -364,7 +364,7 @@ Socket.prototype.end = function(data, encoding) {
   DTRACE_NET_STREAM_END(this);
 
   // just in case we're waiting for an EOF.
-  if (!this._readableState.endEmitted)
+  if (this.readable && !this._readableState.endEmitted)
     this.read(0);
   return;
 };

test/simple/test-stdout-cannot-be-closed-child-process-pipe.js

@@ -0,0 +1,52 @@
+// 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');
+
+if (process.argv[2] === 'child')
+  process.stdout.end('foo');
+else
+  parent();
+
+function parent() {
+  var spawn = require('child_process').spawn;
+  var child = spawn(process.execPath, [__filename, 'child']);
+  var out = '';
+  var err = '';
+
+  child.stdout.setEncoding('utf8');
+  child.stderr.setEncoding('utf8');
+
+  child.stdout.on('data', function(c) {
+    out += c;
+  });
+  child.stderr.on('data', function(c) {
+    err += c;
+  });
+
+  child.on('close', function(code, signal) {
+    assert(code);
+    assert.equal(out, 'foo');
+    assert(/process\.stdout cannot be closed/.test(err));
+    console.log('ok');
+  });
+}