public static byte[] readFile(String fileName) {
    File file = new File(fileName);
    return readFile(file);
  }
Reads the named file, translating {@link IOException} to a {@link RuntimeException} of some
sort.

@param fileName {@code non-null;} name of the file to read
@return {@code non-null;} contents of the file
android/android_framework/dex-maker/src/main/java/com/android/dex/util/FileUtils.java