stream: improve Readable.from error handling

benjamingr · benjamingr · commit 03380bc16aaf · 2021-02-03T12:04:37.000+02:00
PR-URL: #37158 Reviewed-By: Robert Nagy <ronagy@icloud.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
diff --git a/lib/internal/streams/from.js b/lib/internal/streams/from.js
@@ -43,9 +43,6 @@ function from(Readable, iterable, opts) {
   // being called before last iteration completion.
   let reading = false;
 
-  // Flag for when iterator needs to be explicitly closed.
-  let needToClose = false;
-
   readable._read = function() {
     if (!reading) {
       reading = true;
@@ -54,19 +51,23 @@ function from(Readable, iterable, opts) {
   };
 
   readable._destroy = function(error, cb) {
-    if (needToClose) {
-      needToClose = false;
-      PromisePrototypeThen(
-        close(),
-        () => process.nextTick(cb, error),
-        (e) => process.nextTick(cb, error || e),
-      );
-    } else {
-      cb(error);
-    }
+    PromisePrototypeThen(
+      close(error),
+      () => process.nextTick(cb, error), // nextTick is here in case cb throws
+      (e) => process.nextTick(cb, e || error),
+    );
   };
 
-  async function close() {
+  async function close(error) {
+    const hadError = (error !== undefined) && (error !== null);
+    const hasThrow = typeof iterator.throw === 'function';
+    if (hadError && hasThrow) {
+      const { value, done } = await iterator.throw(error);
+      await value;
+      if (done) {
+        return;
+      }
+    }
     if (typeof iterator.return === 'function') {
       const { value } = await iterator.return();
       await value;
@@ -75,13 +76,9 @@ function from(Readable, iterable, opts) {
 
   async function next() {
     try {
-      needToClose = false;
       const { value, done } = await iterator.next();
-      needToClose = !done;
       if (done) {
         readable.push(null);
-      } else if (readable.destroyed) {
-        await close();
       } else {
         const res = await value;
         if (res === null) {
diff --git a/test/parallel/test-readable-from.js b/test/parallel/test-readable-from.js
@@ -4,6 +4,7 @@ const { mustCall } = require('../common');
 const { once } = require('events');
 const { Readable } = require('stream');
 const { strictEqual, throws } = require('assert');
+const common = require('../common');
 
 {
   throws(() => {
@@ -187,6 +188,25 @@ async function endWithError() {
   }
 }
 
+async function destroyingStreamWithErrorThrowsInGenerator() {
+  const validateError = common.mustCall((e) => {
+    strictEqual(e, 'Boum');
+  });
+  async function* generate() {
+    try {
+      yield 1;
+      yield 2;
+      yield 3;
+      throw new Error();
+    } catch (e) {
+      validateError(e);
+    }
+  }
+  const stream = Readable.from(generate());
+  stream.read();
+  stream.once('error', common.mustCall());
+  stream.destroy('Boum');
+}
 
 Promise.all([
   toReadableBasicSupport(),
@@ -198,5 +218,6 @@ Promise.all([
   toReadableOnDataNonObject(),
   destroysTheStreamWhenThrowing(),
   asTransformStream(),
-  endWithError()
+  endWithError(),
+  destroyingStreamWithErrorThrowsInGenerator(),
 ]).then(mustCall());
