public static String computeSHA256DigestOfFile()

in ioXt/uraniborg/AndroidStudioProject/Hubble/app/src/main/java/com/uraniborg/hubble/Utilities.java [58:109]

45 lines of code
9 McCabe index (conditional complexity)


  public static String computeSHA256DigestOfFile(Context context, String pathToFile) {
    final String TAG = "SHA256-File";
    MessageDigest md = null;
    try {
      md = MessageDigest.getInstance("SHA256");
      md.reset();
    } catch (NoSuchAlgorithmException e) {
      Log.e(TAG, "SHA256 isn't implemented on this device.");
      return null;
    }
    File f = new File(pathToFile);
    FileInputStream fis;
    try {
      fis = new FileInputStream(f);
    } catch (FileNotFoundException e) {
      Log.e(TAG, String.format("File %s is not found on the system!", f.getAbsolutePath()));
      return null;
    }
    DigestInputStream dis = new DigestInputStream(fis, md);
    long filesize = f.length();
    if (filesize == 0) {
      Log.e(TAG, String.format("%s is an empty file", pathToFile));
      return null;
    }

    // decide on buffer size based on device's memory class
    ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
    if (am == null) {
      Log.e(TAG, String.format("Error obtaining ActivityManager"));
      return null;
    }
    int bufferSize = (int) (am.isLowRamDevice() ? 512 : 8 * Kilobyte);
    bufferSize = (int) Math.min(filesize, bufferSize);

    byte[] buffer = new byte[bufferSize];

    try {
      while (dis.read(buffer) != -1) {}

    } catch (IOException e) {
      Log.e(TAG, String.format("Failed to read from %s due to %s", pathToFile, e.getMessage()));
      return null;
    }

    try {
      dis.close();
    } catch (IOException e) {
      Log.w(TAG, String.format("Failed to close DigestInputStream"));
    }

    return convertBytesToHexString(md.digest());
  }