001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.utils;
021
022import java.io.IOException;
023import java.io.InputStream;
024import java.net.URI;
025import java.net.URL;
026
027import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
028
029/**
030 * Utility methods for suppression filters.
031 *
032 * @author Timur Tibeyev.
033 */
034public final class FilterUtils {
035
036    /** Stop instances being created. **/
037    private FilterUtils() {
038
039    }
040
041    /**
042     * Checks if suppression source with given fileName exists.
043     * @param fileName name of the suppressions file.
044     * @return true if suppression file exists, otherwise false
045     */
046    public static boolean isFileExists(String fileName) {
047        boolean suppressionSourceExists = true;
048        InputStream sourceInput = null;
049        try {
050            final URI uriByFilename = CommonUtils.getUriByFilename(fileName);
051            final URL url = uriByFilename.toURL();
052            sourceInput = url.openStream();
053        }
054        catch (CheckstyleException | IOException ignored) {
055            suppressionSourceExists = false;
056        }
057        finally {
058            suppressionSourceExists = closeQuietlyWithResult(sourceInput, suppressionSourceExists);
059        }
060        return suppressionSourceExists;
061    }
062
063    /**
064     * Close input.
065     * This method is required till https://github.com/cobertura/cobertura/issues/170
066     * @param sourceInput stream to close
067     * @param suppressionSourceExists previous state of flag
068     * @return result of close operation
069     */
070    private static boolean closeQuietlyWithResult(InputStream sourceInput,
071                                                  boolean suppressionSourceExists) {
072        boolean closed = suppressionSourceExists;
073        if (sourceInput != null) {
074            try {
075                sourceInput.close();
076            }
077            catch (IOException ignored) {
078                closed = false;
079            }
080        }
081        return closed;
082    }
083}