isDirectory

This method uses a trick of lstat to check if a path is a directory, or a symlink to a directory.

declare class AdbSync {
  isDirectory(path: string): Promise<boolean>;
}

As stated in lstat/stat page, sync protocol doesn't support stat system call (which follows symlinks) until Android 8. This method doesn't use stat to follow symlinks, but appends a / to the path and calls lstat instead. Which means this method works on all Android versions.

If a file system error (e.g. target not exist) occurs, this method will return false.

Example

const isDirectory = await sync.isDirectory("/sdcard");

Equivalent ADB command

Although not exactly the same:

adb shell stat -L -c %F /sdcard

Internal API

info

Note: This is an internal API that is usually not needed directly. Most users should use the public API (adb.sync.isDirectory) instead.

The isDirectory method uses AdbSync.Stat.lstat() internally with a path modification:

import type { SocketPool } from "@yume-chan/adb";
import { AdbSync } from "@yume-chan/adb";

declare const pool: SocketPool;
declare const path: string;

try {
  // Appends "/" to path and calls lstat
  await AdbSync.Stat.lstat(pool, path + "/", {
    version: 2, // or 1 for legacy protocol
  });
  return true; // If lstat succeeds, it's a directory
} catch {
  return false; // If lstat fails, it's not a directory
}

How it works

The trick works because:

1. On Unix-like systems (including Android), appending / to a path forces the kernel to check if the path is a directory
2. If the path is a directory or symlink to a directory, lstat succeeds
3. If the path is a file or doesn't exist, lstat fails with an error

This approach works on all Android versions, unlike stat which requires Android 8+ for symlink resolution.