001/*
002 * Copyright 2015 DuraSpace, Inc.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.fcrepo.kernel.modeshape.utils;
017
018import org.fcrepo.kernel.api.exception.RepositoryRuntimeException;
019import org.fcrepo.kernel.api.utils.CacheEntry;
020import org.fcrepo.kernel.api.utils.ContentDigest;
021import org.fcrepo.kernel.api.utils.FixityResult;
022
023import org.slf4j.Logger;
024
025import java.io.IOException;
026import java.net.URI;
027import java.security.MessageDigest;
028import java.security.NoSuchAlgorithmException;
029import java.util.Collection;
030
031import static java.util.Arrays.asList;
032import static org.slf4j.LoggerFactory.getLogger;
033
034/**
035 * Cache entry that wraps a binary stream and provides
036 * fixity methods against it
037 *
038 * @author fasseg
039 */
040public abstract class BasicCacheEntry implements CacheEntry {
041
042    public static final int DEV_NULL_BUFFER_SIZE = 4096;
043
044    private static final byte[] devNull = new byte[DEV_NULL_BUFFER_SIZE];
045
046    private static final Logger LOGGER = getLogger(BasicCacheEntry.class);
047
048    /**
049     * Calculate the fixity of a CacheEntry by piping it through
050     * a simple fixity-calculating InputStream
051     *
052     * @param digest the digest
053     * @return the fixity of this cache entry
054     */
055    @Override
056    public Collection<FixityResult> checkFixity(final String digest) {
057
058        try (FixityInputStream fixityInputStream = new FixityInputStream(this.getInputStream(),
059                MessageDigest.getInstance(digest))) {
060            // exhaust our source
061            while (fixityInputStream.read(devNull) != -1) { }
062
063            final URI calculatedChecksum = ContentDigest.asURI(digest,
064                                                                  fixityInputStream.getMessageDigest().digest());
065            final FixityResult result =
066                new FixityResultImpl(this,
067                                    fixityInputStream.getByteCount(),
068                                    calculatedChecksum);
069
070            LOGGER.debug("Got {}", result.toString());
071
072            return asList(result);
073        } catch (final IOException e) {
074            LOGGER.debug("Got error closing input stream: {}", e);
075            throw new RepositoryRuntimeException(e);
076        } catch (final NoSuchAlgorithmException e1) {
077            throw new RepositoryRuntimeException(e1);
078        }
079    }
080}