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/*
* Copyright 2013-2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Portions copyright 2006-2009 James Murty. Please see LICENSE.txt
* for applicable license terms and NOTICE.txt for applicable notices.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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.amazonaws.services.s3.internal;
import com.amazonaws.internal.SdkFilterInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* Common base class used to wrap an InputStream with a cipher input stream to
* encrypt it, and handles resets by attempting to reset on the original,
* unencrypted data InputStream, and recreate an identical Cipher and identical
* CipherInputStream on the original data.
*
* It's repeatable if and only if the underlying unencryptedDataStream is
* repeatable - if the underlying input stream is not repeatable and you're
* going to buffer to make it repeatable anyways, it makes more sense to do so
* after wrapping in this object, so we buffer the encrypted data and don't have
* to bother re-encrypting on retry.
*
* This stream only supports being marked before the first call to
* {@code read} or {@code skip}, since it's not possible to rewind the
* encryption state of a {@code CipherInputStream} to an arbitrary point. If you
* call {@code mark} after calling {@code read} or {@code skip}, it will throw
* an {@code UnsupportedOperationException}.
*
* @param The input stream.
*/
public abstract class AbstractRepeatableCipherInputStream
extends SdkFilterInputStream {
private final T cipherFactory;
private final InputStream unencryptedDataStream;
private boolean hasBeenAccessed;
/**
* Constructs a new repeatable cipher input stream using the specified
* InputStream as the source data, and the CipherFactory for building Cipher
* objects.
*
* @param input The original, unencrypted data stream. This stream should be
* markable/resetable in order for this class to work correctly.
* @param cipherInputStream The cipher input stream wrapping the original
* input stream
* @param cipherFactory The factory used for creating identical cipher
* objects when this stream is reset and a new CipherInputStream
* is needed.
*/
protected AbstractRepeatableCipherInputStream(final InputStream input,
final FilterInputStream cipherInputStream,
final T cipherFactory) {
super(cipherInputStream);
this.unencryptedDataStream = input;
this.cipherFactory = cipherFactory;
}
@Override
public boolean markSupported() {
abortIfNeeded();
return unencryptedDataStream.markSupported();
}
@Override
public void mark(final int readlimit) {
abortIfNeeded();
if (hasBeenAccessed) {
throw new UnsupportedOperationException(
"Marking is only supported before your first call to "
+ "read or skip.");
}
unencryptedDataStream.mark(readlimit);
}
@Override
public void reset() throws IOException {
abortIfNeeded();
unencryptedDataStream.reset();
in = createCipherInputStream(unencryptedDataStream, cipherFactory);
hasBeenAccessed = false;
}
@Override
public int read() throws IOException {
hasBeenAccessed = true;
return super.read();
}
@Override
public int read(final byte[] b) throws IOException {
hasBeenAccessed = true;
return super.read(b);
}
@Override
public int read(final byte[] b, final int off, final int len)
throws IOException {
hasBeenAccessed = true;
return super.read(b, off, len);
}
@Override
public long skip(final long n) throws IOException {
hasBeenAccessed = true;
return super.skip(n);
}
@SuppressWarnings("checkstyle:hiddenfield")
protected abstract FilterInputStream createCipherInputStream(
InputStream unencryptedDataStream, T cipherFactory);
}