Fixed readlink not throwing EINVAL if the path was not a symlink (#215)

Author: lyonbot

src/vfs/promises.ts

@@ -1025,6 +1025,7 @@ export async function readlink(
 	options?: fs.BufferEncodingOption | fs.EncodingOption | string | null
 ): Promise<string | Buffer> {
 	await using handle = await _open(this, normalizePath(path), { flag: 'r', mode: 0o644, preserveSymlinks: true });
+	if (!isSymbolicLink(handle.inode)) throw new ErrnoError(Errno.EINVAL, 'Not a symbolic link: ' + path);
 	const value = await handle.readFile();
 	const encoding = typeof options == 'object' ? options?.encoding : options;
 	// always defaults to utf-8 to avoid wrangler (cloudflare) worker "unknown encoding" exception

tests/fs/links.test.ts

@@ -21,6 +21,7 @@ suite('Links', () => {
 	test('readlink', async () => {
 		const destination = await fs.promises.readlink(symlink);
 		assert.equal(destination, target);
+		assert.throws(() => fs.readlinkSync(destination));
 	});
 
 	test('read target contents', async () => {