vfs: convert underscore-prefixed methods to private class fields

Replace all _-prefixed methods with # private class fields across VFS
provider classes. Since #checkClosed was defined on the base class
VirtualFileHandle and called by subclasses via inheritance, each
subclass now gets its own #checkClosed using the public closed getter.
Also removes unused _rawContent getter from MemoryFileHandle.

Author: mcollina

lib/internal/vfs/file_handle.js

@@ -92,9 +92,8 @@ class VirtualFileHandle {
 
   /**
    * Throws if the handle is closed.
-   * @private
    */
-  _checkClosed() {
+  #checkClosed() {
     if (this[kClosed]) {
       throw createEBADF('read');
     }
@@ -109,7 +108,7 @@ class VirtualFileHandle {
    * @returns {Promise<{ bytesRead: number, buffer: Buffer }>}
    */
   async read(buffer, offset, length, position) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('read');
   }
 
@@ -122,7 +121,7 @@ class VirtualFileHandle {
    * @throws {ERR_METHOD_NOT_IMPLEMENTED} When not implemented by subclass
    */
   readSync(buffer, offset, length, position) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('readSync');
   }
 
@@ -135,7 +134,7 @@ class VirtualFileHandle {
    * @returns {Promise<{ bytesWritten: number, buffer: Buffer }>}
    */
   async write(buffer, offset, length, position) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('write');
   }
 
@@ -148,7 +147,7 @@ class VirtualFileHandle {
    * @throws {ERR_METHOD_NOT_IMPLEMENTED} When not implemented by subclass
    */
   writeSync(buffer, offset, length, position) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('writeSync');
   }
 
@@ -158,7 +157,7 @@ class VirtualFileHandle {
    * @returns {Promise<Buffer|string>}
    */
   async readFile(options) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('readFile');
   }
 
@@ -168,7 +167,7 @@ class VirtualFileHandle {
    * @throws {ERR_METHOD_NOT_IMPLEMENTED} When not implemented by subclass
    */
   readFileSync(options) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('readFileSync');
   }
 
@@ -179,7 +178,7 @@ class VirtualFileHandle {
    * @returns {Promise<void>}
    */
   async writeFile(data, options) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('writeFile');
   }
 
@@ -189,7 +188,7 @@ class VirtualFileHandle {
    * @param {object} [options] Options
    */
   writeFileSync(data, options) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('writeFileSync');
   }
 
@@ -199,7 +198,7 @@ class VirtualFileHandle {
    * @returns {Promise<Stats>}
    */
   async stat(options) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('stat');
   }
 
@@ -209,7 +208,7 @@ class VirtualFileHandle {
    * @throws {ERR_METHOD_NOT_IMPLEMENTED} When not implemented by subclass
    */
   statSync(options) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('statSync');
   }
 
@@ -219,7 +218,7 @@ class VirtualFileHandle {
    * @returns {Promise<void>}
    */
   async truncate(len) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('truncate');
   }
 
@@ -228,7 +227,7 @@ class VirtualFileHandle {
    * @param {number} [len] The new length
    */
   truncateSync(len) {
-    this._checkClosed();
+    this.#checkClosed();
     throw new ERR_METHOD_NOT_IMPLEMENTED('truncateSync');
   }
 
@@ -257,6 +256,12 @@ class MemoryFileHandle extends VirtualFileHandle {
   #entry;
   #getStats;
 
+  #checkClosed() {
+    if (this.closed) {
+      throw createEBADF('read');
+    }
+  }
+
   /**
    * @param {string} path The file path
    * @param {string} flags The open flags
@@ -310,14 +315,6 @@ class MemoryFileHandle extends VirtualFileHandle {
     return this.#content;
   }
 
-  /**
-   * Gets the raw stored content (without dynamic resolution).
-   * @returns {Buffer}
-   */
-  get _rawContent() {
-    return this.#content;
-  }
-
   /**
    * Reads data from the file synchronously.
    * @param {Buffer} buffer The buffer to read into
@@ -327,7 +324,7 @@ class MemoryFileHandle extends VirtualFileHandle {
    * @returns {number} The number of bytes read
    */
   readSync(buffer, offset, length, position) {
-    this._checkClosed();
+    this.#checkClosed();
 
     // Get content (resolves dynamic content providers)
     const content = this.content;
@@ -371,7 +368,7 @@ class MemoryFileHandle extends VirtualFileHandle {
    * @returns {number} The number of bytes written
    */
   writeSync(buffer, offset, length, position) {
-    this._checkClosed();
+    this.#checkClosed();
 
     const writePos = position !== null && position !== undefined ? position : this.position;
     const data = buffer.subarray(offset, offset + length);
@@ -419,7 +416,7 @@ class MemoryFileHandle extends VirtualFileHandle {
    * @returns {Buffer|string}
    */
   readFileSync(options) {
-    this._checkClosed();
+    this.#checkClosed();
 
     // Get content (resolves dynamic content providers)
     const content = this.content;
@@ -436,7 +433,7 @@ class MemoryFileHandle extends VirtualFileHandle {
    * @returns {Promise<Buffer|string>}
    */
   async readFile(options) {
-    this._checkClosed();
+    this.#checkClosed();
 
     // Get content asynchronously (supports async content providers)
     const content = await this.getContentAsync();
@@ -454,7 +451,7 @@ class MemoryFileHandle extends VirtualFileHandle {
    * @param {object} [options] Options
    */
   writeFileSync(data, options) {
-    this._checkClosed();
+    this.#checkClosed();
 
     const buffer = typeof data === 'string' ? Buffer.from(data, options?.encoding) : data;
 
@@ -493,7 +490,7 @@ class MemoryFileHandle extends VirtualFileHandle {
    * @returns {Stats}
    */
   statSync(options) {
-    this._checkClosed();
+    this.#checkClosed();
     if (this.#getStats) {
       return this.#getStats(this.#content.length);
     }
@@ -514,7 +511,7 @@ class MemoryFileHandle extends VirtualFileHandle {
    * @param {number} [len] The new length
    */
   truncateSync(len = 0) {
-    this._checkClosed();
+    this.#checkClosed();
 
     if (len < this.#content.length) {
       this.#content = this.#content.subarray(0, len);