stream: avoid writeAfterEnd() while ending

Calling `writable.end()` will probably synchronously call
`writable.write()`, in such a situation the `state.ended`
is false and `writable.write()` doesn't trigger `writeAfterEnd()`.

PR-URL: nodejs#18170
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/_stream_writable.js

@@ -273,7 +273,7 @@ Writable.prototype.write = function(chunk, encoding, cb) {
   if (typeof cb !== 'function')
     cb = nop;
 
-  if (state.ended)
+  if (state.ending)
     writeAfterEnd(this, cb);
   else if (isBuf || validChunk(this, state, chunk, cb)) {
     state.pendingcb++;

test/parallel/test-stream-writable-write-writev-finish.js

@@ -154,3 +154,27 @@ const stream = require('stream');
   };
   rs.pipe(ws);
 }
+
+{
+  const w = new stream.Writable();
+  w._write = (chunk, encoding, cb) => {
+    process.nextTick(cb);
+  };
+  w.on('error', common.mustCall());
+  w.on('prefinish', () => {
+    w.write("shouldn't write in prefinish listener");
+  });
+  w.end();
+}
+
+{
+  const w = new stream.Writable();
+  w._write = (chunk, encoding, cb) => {
+    process.nextTick(cb);
+  };
+  w.on('error', common.mustCall());
+  w.on('finish', () => {
+    w.write("should't write in finish listener");
+  });
+  w.end();
+}