stream: call write cb before finish event

Since 049903e, an end callback could be called before a write
callback if end() is called before the write is done. This patch
resolves the issue.

In collaboration with @gne

Fixes felixge/node-formidable#209
Fixes #5215

1 files changed, 15 insertions, 6 deletions

diff --git a/lib/_stream_writable.js b/lib/_stream_writable.js
index 346f2cc96ab..c060e015a05 100644
--- a/lib/_stream_writable.js
+++ b/lib/_stream_writable.js
@@ -240,7 +240,8 @@ function onwrite(stream, er) {
   if (er)
     onwriteError(stream, state, sync, er, cb);
   else {
-    var finished = finishMaybe(stream, state);
+    // Check if we're actually ready to finish, but don't emit yet
+    var finished = needFinish(stream, state);
 
     if (!finished && !state.bufferProcessing && state.buffer.length)
       clearBuffer(stream, state);
@@ -259,6 +260,8 @@ function afterWrite(stream, state, finished, cb) {
   if (!finished)
     onwriteDrain(stream, state);
   cb();
+  if (finished)
+    finishMaybe(stream, state);
 }
 
 // Must force callback to be called on nextTick, so that we don't
@@ -326,15 +329,21 @@ Writable.prototype.end = function(chunk, encoding, cb) {
     endWritable(this, state, cb);
 };
 
+
+function needFinish(stream, state) {
+  return (state.ending &&
+          state.length === 0 &&
+          !state.finished &&
+          !state.writing);
+}
+
 function finishMaybe(stream, state) {
-  if (state.ending &&
-      state.length === 0 &&
-      !state.finished &&
-      !state.writing) {
+  var need = needFinish(stream, state);
+  if (need) {
     state.finished = true;
     stream.emit('finish');
   }
-  return state.finished;
+  return need;
 }
 
 function endWritable(stream, state, cb) {