001/**
002 * Copyright 2014 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.impl.utils;
017
018import com.google.common.collect.ImmutableSet;
019import org.apache.commons.io.IOUtils;
020import org.fcrepo.kernel.utils.CacheEntry;
021import org.fcrepo.kernel.utils.ContentDigest;
022import org.fcrepo.kernel.utils.FixityResult;
023import org.slf4j.Logger;
024
025import javax.jcr.RepositoryException;
026import java.io.IOException;
027import java.net.URI;
028import java.security.MessageDigest;
029import java.security.NoSuchAlgorithmException;
030import java.util.Collection;
031
032import static com.google.common.base.Throwables.propagate;
033import static org.apache.commons.io.output.NullOutputStream.NULL_OUTPUT_STREAM;
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 Logger LOGGER = getLogger(BasicCacheEntry.class);
045
046    /**
047     * Calculate the fixity of a CacheEntry by piping it through
048     * a simple fixity-calculating InputStream
049     *
050     * @return the fixity of this cache entry
051     * @throws RepositoryException
052     */
053    @Override
054    public Collection<FixityResult> checkFixity(final String digest)
055        throws RepositoryException {
056
057        try (FixityInputStream fixityInputStream = new FixityInputStream(this.getInputStream(),
058                MessageDigest.getInstance(digest))) {
059
060            IOUtils.copy(fixityInputStream, NULL_OUTPUT_STREAM);
061
062            final URI calculatedChecksum = ContentDigest.asURI(digest,
063                                                                  fixityInputStream.getMessageDigest().digest());
064            final FixityResult result =
065                new FixityResultImpl(this,
066                                    fixityInputStream.getByteCount(),
067                                    calculatedChecksum);
068
069            LOGGER.debug("Got {}", result.toString());
070
071            return ImmutableSet.of(result);
072        } catch (final IOException e) {
073            LOGGER.debug("Got error closing input stream: {}", e);
074            throw propagate(e);
075        } catch (final NoSuchAlgorithmException e1) {
076            throw propagate(e1);
077        }
078
079    }
080}