has_permission.dart

/// See http://dartbug.com/22036
library has_permission;

import 'dart:io';

enum FilePermission { READ, WRITE, EXECUTE, SET_UID, SET_GID, STICKY }
enum FilePermissionRole { WORLD, GROUP, USER }

bool hasPermission(FileStat stat, FilePermission permission, {FilePermissionRole role: FilePermissionRole.WORLD}) {
  var bitIndex = _getPermissionBitIndex(permission, role);
  return (stat.mode & (1 << bitIndex)) != 0;
}

int _getPermissionBitIndex(FilePermission permission, FilePermissionRole role) {
  switch (permission) {
    case FilePermission.SET_UID: return 11;
    case FilePermission.SET_GID: return 10;
    case FilePermission.STICKY: return 9;
    default: return (role.index * 3) + permission.index;
  }
}