stream: correctly pause and resume after once('readable')

Fixes: https://github.com/nodejs/node/issues/24281

PR-URL: https://github.com/nodejs/node/pull/24366
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/lib/_stream_readable.js b/lib/_stream_readable.js
index 2a2122e0e5..47dbae31b5 100644
--- a/lib/_stream_readable.js
+++ b/lib/_stream_readable.js
@@ -114,6 +114,7 @@ function ReadableState(options, stream, isDuplex) {
   this.emittedReadable = false;
   this.readableListening = false;
   this.resumeScheduled = false;
+  this.paused = true;
 
   // Should close be emitted on destroy. Defaults to true.
   this.emitClose = options.emitClose !== false;
@@ -862,10 +863,16 @@ Readable.prototype.removeAllListeners = function(ev) {
 };
 
 function updateReadableListening(self) {
-  self._readableState.readableListening = self.listenerCount('readable') > 0;
+  const state = self._readableState;
+  state.readableListening = self.listenerCount('readable') > 0;
 
-  // crude way to check if we should resume
-  if (self.listenerCount('data') > 0) {
+  if (state.resumeScheduled && !state.paused) {
+    // flowing needs to be set to true now, otherwise
+    // the upcoming resume will not flow.
+    state.flowing = true;
+
+    // crude way to check if we should resume
+  } else if (self.listenerCount('data') > 0) {
     self.resume();
   }
 }
@@ -887,6 +894,7 @@ Readable.prototype.resume = function() {
     state.flowing = !state.readableListening;
     resume(this, state);
   }
+  state.paused = false;
   return this;
 };
 
@@ -917,6 +925,7 @@ Readable.prototype.pause = function() {
     this._readableState.flowing = false;
     this.emit('pause');
   }
+  this._readableState.paused = true;
   return this;
 };