MessageDigestSink.java

/*
 * Copyright (C) 2016 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.apksig.internal.util;

import com.android.apksig.util.DataSink;
import java.nio.ByteBuffer;
import java.security.MessageDigest;

/**
 * Data sink which feeds all received data into the associated {@link MessageDigest} instances. Each
 * {@code MessageDigest} instance receives the same data.
 */
public class MessageDigestSink implements DataSink {

    private final MessageDigest[] mMessageDigests;

    public MessageDigestSink(MessageDigest[] digests) {
        mMessageDigests = digests;
    }

    @Override
    public void consume(byte[] buf, int offset, int length) {
        for (MessageDigest md : mMessageDigests) {
            md.update(buf, offset, length);
        }
    }

    @Override
    public void consume(ByteBuffer buf) {
        int originalPosition = buf.position();
        for (MessageDigest md : mMessageDigests) {
            // Reset the position back to the original because the previous iteration's
            // MessageDigest.update set the buffer's position to the buffer's limit.
            buf.position(originalPosition);
            md.update(buf);
        }
    }
}