IOUtil.java

/*
 * XML Format Maven Plugin (https://github.com/acegi/xml-format-maven-plugin)
 *
 * Copyright 2011-2026 Acegi Technology Pty Limited.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License 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 au.com.acegi.xmlformat;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;
import java.util.zip.Checksum;

/**
 * Utility methods for dealing with I/O resources.
 */
final class IOUtil {

    private IOUtil() {
    }

    /**
     * Returns a CRC32 of the provided input stream.
     *
     * @param in
     *            to CRC32
     *
     * @return the CRC32 value
     *
     * @throws IOException
     *             if unable to read the input stream
     */
    @SuppressWarnings("PMD.EmptyWhileStmt")
    static long hash(final InputStream in) throws IOException {
        final Checksum cksum = new CRC32();
        final CheckedInputStream is = new CheckedInputStream(in, cksum);
        final byte[] buff = new byte[4_096];
        while (is.read(buff) >= 0) {
            // CheckInputStream will update its internal checksum
        }
        return is.getChecksum().getValue();
    }

    /**
     * Returns a CRC32 of the given file.
     *
     * @param file
     *            to CRC32
     *
     * @return the CRC32 value
     *
     * @throws IOException
     *             if unable to read the file
     */
    static long hash(final File file) throws IOException {
        try (InputStream fis = Files.newInputStream(file.toPath())) {
            return hash(fis);
        }
    }

}