Function isSubdir

common/src/util/file.ts:322–335

(fromPath: string, toPath: string)

 * Returns true if the `toPath` is a subdirectory of `fromPath`.
 */
export function isSubdir(fromPath: string, toPath: string) {
  const resolvedFrom = path.resolve(fromPath)
  const resolvedTo = path.resolve(toPath)

  if (process.platform === 'win32') {
    const fromDrive = path.parse(resolvedFrom).root.toLowerCase()
    const toDrive = path.parse(resolvedTo).root.toLowerCase()
    if (fromDrive !== toDrive) {
      return false
    }
  }

  return !path.relative(resolvedFrom, resolvedTo).startsWith('..')
}

export function isValidProjectRoot(dir: string): boolean {
  return !isSubdir(dir, os.homedir())