jdk/src/java.base/share/classes/com/sun/crypto/provider/AEADBufferedStream.java
Anthony Scarpino dc9c77bebe 8318756: Create better internal buffer for AEADs
Reviewed-by: djelinski
2023-12-06 18:09:10 +00:00

109 lines
3.5 KiB
Java

/*
* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.crypto.provider;
import jdk.internal.util.ArraysSupport;
import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.HexFormat;
/**
* This class extends ByteArrayOutputStream by optimizing internal buffering.
* It skips bounds checking, as the buffers are known and input previously
* checked. toByteArray() returns the internal buffer to avoid an extra copy.
*
* This uses `count` to determine the state of `buf`. `buf` can still
* point to an array while `count` equals zero.
*/
final class AEADBufferedStream extends ByteArrayOutputStream {
/**
* Create an instance with the specified buffer
*/
public AEADBufferedStream(int len) {
super(len);
}
/**
* This method saves memory by returning the internal buffer. The calling
* method must use {@code size()} for the relevant data length as the
* returning byte[] maybe larger.
*
* @return internal buffer.
*/
public byte[] getBuffer() {
return buf;
}
/**
* This method with expand the buffer if {@code count} + {@code len}
* is larger than the buffer byte[] length.
* @param len length to add to the current buffer
*/
private void checkCapacity(int len) {
int blen = buf.length;
// Create a new larger buffer and append the new data
if (blen < count + len) {
buf = Arrays.copyOf(buf, ArraysSupport.newLength(blen, len, blen));
}
}
/**
* Takes a ByteBuffer writing non-blocksize data directly to the internal
* buffer.
* @param src remaining non-blocksize ByteBuffer
*/
public void write(ByteBuffer src) {
int pos = src.position();
int len = src.remaining();
if (src.hasArray()) {
write(src.array(), pos + src.arrayOffset(), len);
src.position(pos + len);
return;
}
checkCapacity(len);
src.get(buf, count, len);
count += len;
}
@Override
public void write(byte[] in, int offset, int len) {
checkCapacity(len);
System.arraycopy(in, offset, buf, count, len);
count += len;
}
@Override
public String toString() {
return (count == 0 ? "null" : HexFormat.of().formatHex(buf));
}
}