Function isSubpath

packages/cli-exec/src/fsutils.ts:76–85

(parent: string, child: string)

 * Returns whether `child` is equal to or nested below `parent`.
 */
export function isSubpath(parent: string, child: string): boolean {
  const relativePath = path.relative(parent, child);

  return (
    relativePath === '' ||
    (relativePath !== '' &&
      !relativePath.startsWith('..') &&
      !path.isAbsolute(relativePath))
  );
}

/**
 * Strips Windows executable extensions before matching package bin names.