fs: make Dir disposers idempotent

doc/api/fs.md

@@ -6773,8 +6773,8 @@ changes:
    description: No longer experimental.
 -->
 
-Calls `dir.close()` and returns a promise that fulfills when the
-dir is closed.
+Calls `dir.close()` if the directory handle is open, and returns a promise that
+fulfills when disposal is complete.
 
 #### `dir[Symbol.dispose]()`
 
@@ -6786,7 +6786,8 @@ changes:
    description: No longer experimental.
 -->
 
-Calls `dir.closeSync()` and returns `undefined`.
+Calls `dir.closeSync()` if the directory handle is open, and returns
+`undefined`.
 
 ### Class: `fs.Dirent`
 

lib/internal/fs/dir.js

@@ -24,7 +24,6 @@ const {
 
 const { FSReqCallback } = binding;
 const {
-  assignFunctionName,
   promisify,
 } = require('internal/util');
 const {
@@ -296,31 +295,24 @@ class Dir {
       await this.#closePromisified();
     }
   }
+
+  [SymbolDispose]() {
+    if (this.#closed) return;
+    this.closeSync();
+  }
+
+  async [SymbolAsyncDispose]() {
+    if (this.#closed) return;
+    await this.#closePromisified();
+  }
 }
 
-const nonEnumerableDescriptor = {
-  enumerable: false,
-  writable: true,
-  configurable: true,
-};
 ObjectDefineProperties(Dir.prototype, {
-  [SymbolDispose]: {
-    __proto__: null,
-    ...nonEnumerableDescriptor,
-    value: assignFunctionName(SymbolDispose, function() {
-      this.closeSync();
-    }),
-  },
-  [SymbolAsyncDispose]: {
-    __proto__: null,
-    ...nonEnumerableDescriptor,
-    value: assignFunctionName(SymbolAsyncDispose, function() {
-      this.close();
-    }),
-  },
   [SymbolAsyncIterator]: {
     __proto__: null,
-    ...nonEnumerableDescriptor,
+    enumerable: false,
+    writable: true,
+    configurable: true,
     value: Dir.prototype.entries,
   },
 });

test/parallel/test-fs-promises-file-handle-dispose.js

@@ -11,10 +11,14 @@ async function explicitCall() {
 
   const dh = await fs.opendir(__dirname);
   await dh[Symbol.asyncDispose]();
+  // Repeat invocations should not reject
+  await dh[Symbol.asyncDispose]();
   await assert.rejects(dh.read(), { code: 'ERR_DIR_CLOSED' });
 
   const dhSync = opendirSync(__dirname);
   dhSync[Symbol.dispose]();
+  // Repeat invocations should not throw
+  dhSync[Symbol.dispose]();
   assert.throws(() => dhSync.readSync(), { code: 'ERR_DIR_CLOSED' });
 }