001/*
002 * Licensed to DuraSpace under one or more contributor license agreements.
003 * See the NOTICE file distributed with this work for additional information
004 * regarding copyright ownership.
005 *
006 * DuraSpace licenses this file to you under the Apache License,
007 * Version 2.0 (the "License"); you may not use this file except in
008 * compliance with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.fcrepo.kernel.modeshape.utils;
019
020import org.fcrepo.kernel.api.exception.RepositoryRuntimeException;
021import org.fcrepo.kernel.api.utils.CacheEntry;
022import org.fcrepo.kernel.api.utils.ContentDigest;
023import org.fcrepo.kernel.api.utils.FixityResult;
024
025import org.slf4j.Logger;
026
027import java.io.IOException;
028import java.net.URI;
029import java.security.MessageDigest;
030import java.security.NoSuchAlgorithmException;
031import java.util.Collection;
032
033import static java.util.Arrays.asList;
034import static org.slf4j.LoggerFactory.getLogger;
035
036/**
037 * Cache entry that wraps a binary stream and provides
038 * fixity methods against it
039 *
040 * @author fasseg
041 */
042public abstract class BasicCacheEntry implements CacheEntry {
043
044    private static final int DEV_NULL_BUFFER_SIZE = 4096;
045
046    private static final byte[] devNull = new byte[DEV_NULL_BUFFER_SIZE];
047
048    private static final Logger LOGGER = getLogger(BasicCacheEntry.class);
049
050    /**
051     * Calculate the fixity of a CacheEntry by piping it through
052     * a simple fixity-calculating InputStream
053     *
054     * @param algorithm the digest algorithm to be used
055     * @return the fixity of this cache entry
056     */
057    @Override
058    public Collection<FixityResult> checkFixity(final String algorithm) {
059
060        try (FixityInputStream fixityInputStream = new FixityInputStream(
061                this.getInputStream(), MessageDigest.getInstance(algorithm))) {
062
063            // actually calculate the digest by consuming the stream
064            while (fixityInputStream.read(devNull) != -1) { }
065
066            final URI calculatedChecksum =
067                    ContentDigest.asURI(algorithm, fixityInputStream.getMessageDigest().digest());
068
069            final FixityResult result =
070                new FixityResultImpl(getExternalIdentifier(),
071                                    fixityInputStream.getByteCount(),
072                                    calculatedChecksum,
073                                    algorithm);
074
075            LOGGER.debug("Got {}", result.toString());
076
077            return asList(result);
078        } catch (final IOException e) {
079            LOGGER.debug("Got error closing input stream: {}", e);
080            throw new RepositoryRuntimeException(e);
081        } catch (final NoSuchAlgorithmException e1) {
082            throw new RepositoryRuntimeException(e1);
083        }
084    }
085}