src/com/android/certinstaller/Util.java

/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.certinstaller;

import android.util.Log;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

class Util {
    private static final String TAG = "certinstaller.Util";

    static byte[] toBytes(Object object) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try {
            ObjectOutputStream os = new ObjectOutputStream(baos);
            os.writeObject(object);
            os.close();
        } catch (Exception e) {
            Log.w(TAG, "toBytes(): " + e + ": " + object);
        }
        return baos.toByteArray();
    }

    static <T> T fromBytes(byte[] bytes) {
        if (bytes == null) return null;
        try {
            ObjectInputStream is =
                    new ObjectInputStream(new ByteArrayInputStream(bytes));
            return (T) is.readObject();
        } catch (Exception e) {
            Log.w(TAG, "fromBytes(): " + e);
            return null;
        }
    }

    static String toMd5(byte[] bytes) {
        try {
            MessageDigest algorithm = MessageDigest.getInstance("MD5");
            algorithm.reset();
            algorithm.update(bytes);
            return toHexString(algorithm.digest(), "");
        } catch(NoSuchAlgorithmException e){
            // should not occur
            Log.w(TAG, "toMd5(): " + e);
            throw new RuntimeException(e);
        }
    }

    private static String toHexString(byte[] bytes, String separator) {
        StringBuilder hexString = new StringBuilder();
        for (byte b : bytes) {
            hexString.append(Integer.toHexString(0xFF & b)).append(separator);
        }
        return hexString.toString();
    }

    static byte[] readFile(File file) {
        try {
            byte[] data = new byte[(int) file.length()];
            FileInputStream fis = new FileInputStream(file);
            fis.read(data);
            fis.close();
            return data;
        } catch (Exception e) {
            Log.w(TAG, "cert file read error: " + e);
            return null;
        }
    }

    static boolean deleteFile(File file) {
        if ((file != null) && !file.delete()) {
            Log.w(TAG, "cannot delete cert: " + file);
            return false;
        } else {
            return true;
        }
    }

    private Util() {
    }
}