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This library contains all cryptographic functions that are used by Cryptomator.

There is a newer version: 2.2.0

/*******************************************************************************
 * Copyright (c) 2015, 2016 Sebastian Stenzel and others.
 * This file is licensed under the terms of the MIT license.
 * See the LICENSE.txt file for more info.
 *
 * Contributors:
 *     Sebastian Stenzel - initial API and implementation
 *******************************************************************************/
package org.cryptomator.cryptolib.common;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;

public class ByteBuffers {

	/**
	 * Copies as many bytes as possible from the given source to the destination buffer.
	 * The position of both buffers will be incremented by as many bytes as have been copied.
	 *
	 * @param source      ByteBuffer from which bytes are read
	 * @param destination ByteBuffer into which bytes are written
	 * @return number of bytes copied, i.e. {@link ByteBuffer#remaining() source.remaining()} or {@link ByteBuffer#remaining() destination.remaining()}, whatever is less.
	 */
	public static int copy(ByteBuffer source, ByteBuffer destination) {
		final int numBytes = Math.min(source.remaining(), destination.remaining());
		final ByteBuffer tmp = source.asReadOnlyBuffer();
		tmp.limit(tmp.position() + numBytes);
		destination.put(tmp);
		source.position(tmp.position()); // until now only tmp pos has been incremented, so we need to adjust the position
		return numBytes;
	}

	/**
	 * Fills the given buffer by reading from the given source until either reaching EOF
	 * or buffer has no more {@link ByteBuffer#hasRemaining() remaining space}.
	 *
	 * @param source The channel to read from
	 * @param buffer The buffer to fill
	 * @return Number of bytes read. Will only be less than remaining space in buffer if reaching EOF.
	 * @throws IOException In case of I/O errors
	 */
	public static int fill(ReadableByteChannel source, ByteBuffer buffer) throws IOException {
		final int requested = buffer.remaining();
		while (buffer.hasRemaining()) {
			int read = source.read(buffer);
			if (read == -1) { // EOF
				break;
			}
		}
		return requested - buffer.remaining();
	}

}