fs: prevent multiple invocations of callback in Dir class

Author: 0hmX

lib/internal/fs/dir.js

@@ -115,22 +115,22 @@ class Dir {
       return;
     }
 
+    let dirent;
     if (this.#processHandlerQueue()) {
       try {
-        const dirent = ArrayPrototypeShift(this.#bufferedEntries);
+        dirent = ArrayPrototypeShift(this.#bufferedEntries);
 
         if (this.#options.recursive && dirent.isDirectory()) {
           this.readSyncRecursive(dirent);
         }
-
-        if (maybeSync)
-          process.nextTick(callback, null, dirent);
-        else
-          callback(null, dirent);
-        return;
       } catch (error) {
         return callback(error);
       }
+      if (maybeSync)
+        process.nextTick(callback, null, dirent);
+      else
+        callback(null, dirent);
+      return;
     }
 
     const req = new FSReqCallback();
@@ -145,16 +145,17 @@ class Dir {
         return callback(err, result);
       }
 
+      let dirent;
       try {
         this.processReadResult(this.#path, result);
-        const dirent = ArrayPrototypeShift(this.#bufferedEntries);
+        dirent = ArrayPrototypeShift(this.#bufferedEntries);
         if (this.#options.recursive && dirent.isDirectory()) {
           this.readSyncRecursive(dirent);
         }
-        callback(null, dirent);
       } catch (error) {
-        callback(error);
+        return callback(error);
       }
+      return callback(null, dirent);
     };
 
     this.#operationQueue = [];

test/parallel/test-fs-opendir.js

@@ -4,6 +4,7 @@ const common = require('../common');
 const assert = require('assert');
 const fs = require('fs');
 const path = require('path');
+const test = require('node:test');
 
 const tmpdir = require('../common/tmpdir');
 
@@ -287,3 +288,41 @@ doConcurrentAsyncMixedOps().then(common.mustCall());
   dir.closeSync();
   assert.rejects(dir.close(), dirclosedError).then(common.mustCall());
 }
+
+test('fs.opendir double callback check', async (t) => {
+  let callbackCount = 0;
+
+  await new Promise((resolve, reject) => {
+    fs.opendir('.', (err, dir) => {
+      if (err) return reject(err);
+
+      const cleanup = () => {
+        dir.close((err) => {
+          if (err) {
+            reject(err);
+          }
+        });
+      };
+
+      dir.read((err, dirent) => {
+        callbackCount++;
+        if (callbackCount === 1) throw new Error('User error');
+        if (callbackCount > 1) {
+          reject(new Error('Callback was called multiple times'));
+        }
+      });
+
+      const timeout = setTimeout(() => {
+        cleanup();
+        resolve();
+      }, 1000);
+
+      process.nextTick(() => {
+        if (callbackCount > 1) {
+          clearTimeout(timeout);
+          cleanup();
+        }
+      });
+    });
+  });
+});