stream: fix legacy pipe error handling

lib/internal/streams/legacy.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const {
+  ArrayIsArray,
   ObjectSetPrototypeOf,
 } = primordials;
 
@@ -58,12 +59,12 @@ Stream.prototype.pipe = function(dest, options) {
   function onerror(er) {
     cleanup();
     if (EE.listenerCount(this, 'error') === 0) {
-      throw er; // Unhandled stream error in pipe.
+      this.emit('error', er);
     }
   }
 
-  source.on('error', onerror);
-  dest.on('error', onerror);
+  prependListener(source, 'error', onerror);
+  prependListener(dest, 'error', onerror);
 
   // Remove all the event listeners that were added.
   function cleanup() {
@@ -92,4 +93,22 @@ Stream.prototype.pipe = function(dest, options) {
   return dest;
 };
 
-module.exports = Stream;
+function prependListener(emitter, event, fn) {
+  // Sadly this is not cacheable as some libraries bundle their own
+  // event emitter implementation with them.
+  if (typeof emitter.prependListener === 'function')
+    return emitter.prependListener(event, fn);
+
+  // This is a hack to make sure that our error handler is attached before any
+  // userland ones.  NEVER DO THIS. This is here only because this code needs
+  // to continue to work with older versions of Node.js that do not include
+  // the prependListener() method. The goal is to eventually remove this hack.
+  if (!emitter._events || !emitter._events[event])
+    emitter.on(event, fn);
+  else if (ArrayIsArray(emitter._events[event]))
+    emitter._events[event].unshift(fn);
+  else
+    emitter._events[event] = [fn, emitter._events[event]];
+}
+
+module.exports = { Stream, prependListener };

lib/internal/streams/readable.js

@@ -22,7 +22,6 @@
 'use strict';
 
 const {
-  ArrayIsArray,
   NumberIsInteger,
   NumberIsNaN,
   ObjectDefineProperties,
@@ -38,7 +37,7 @@ module.exports = Readable;
 Readable.ReadableState = ReadableState;
 
 const EE = require('events');
-const Stream = require('internal/streams/legacy');
+const { Stream, prependListener } = require('internal/streams/legacy');
 const { Buffer } = require('buffer');
 
 let debug = require('internal/util/debuglog').debuglog('stream', (fn) => {
@@ -69,24 +68,6 @@ function nop() {}
 
 const { errorOrDestroy } = destroyImpl;
 
-function prependListener(emitter, event, fn) {
-  // Sadly this is not cacheable as some libraries bundle their own
-  // event emitter implementation with them.
-  if (typeof emitter.prependListener === 'function')
-    return emitter.prependListener(event, fn);
-
-  // This is a hack to make sure that our error handler is attached before any
-  // userland ones.  NEVER DO THIS. This is here only because this code needs
-  // to continue to work with older versions of Node.js that do not include
-  // the prependListener() method. The goal is to eventually remove this hack.
-  if (!emitter._events || !emitter._events[event])
-    emitter.on(event, fn);
-  else if (ArrayIsArray(emitter._events[event]))
-    emitter._events[event].unshift(fn);
-  else
-    emitter._events[event] = [fn, emitter._events[event]];
-}
-
 function ReadableState(options, stream, isDuplex) {
   // Duplex streams are both readable and writable, but share
   // the same options object.

lib/internal/streams/writable.js

@@ -38,7 +38,7 @@ module.exports = Writable;
 Writable.WritableState = WritableState;
 
 const EE = require('events');
-const Stream = require('internal/streams/legacy');
+const Stream = require('internal/streams/legacy').Stream;
 const { Buffer } = require('buffer');
 const destroyImpl = require('internal/streams/destroy');
 const {

lib/stream.js

@@ -36,7 +36,7 @@ const internalBuffer = require('internal/buffer');
 // Lazy loaded
 let promises = null;
 
-const Stream = module.exports = require('internal/streams/legacy');
+const Stream = module.exports = require('internal/streams/legacy').Stream;
 Stream.Readable = require('internal/streams/readable');
 Stream.Writable = require('internal/streams/writable');
 Stream.Duplex = require('internal/streams/duplex');

test/parallel/test-stream-pipe-error-handling.js

@@ -22,7 +22,7 @@
 'use strict';
 const common = require('../common');
 const assert = require('assert');
-const Stream = require('stream').Stream;
+const { Stream, PassThrough } = require('stream');
 
 {
   const source = new Stream();
@@ -108,3 +108,17 @@ const Stream = require('stream').Stream;
   w.removeListener('error', () => {});
   removed = true;
 }
+
+{
+  const _err = new Error('this should be handled');
+  const destination = new PassThrough();
+  destination.once('error', common.mustCall((err) => {
+    assert.strictEqual(err, _err);
+  }));
+
+  const stream = new Stream();
+  stream
+    .pipe(destination);
+
+  destination.destroy(_err);
+}