io.github.zlika.reproducible.SortManifestFileStripper Maven / Gradle / Ivy

Go to download
/*
 * 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
 *
 *      http://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 io.github.zlika.reproducible;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

/**
 * Sorts a MANIFEST file by attribute.
 */
final class SortManifestFileStripper implements Stripper
{
    private static final Comparator MANIFEST_ENTRY_COMPARATOR = new Comparator()
    {
        // CHECKSTYLE IGNORE LINE: ReturnCount
        @Override
        public int compare(String o1, String o2)
        {
            if (o1.startsWith("Manifest-Version:"))
            {
                return -1;
            }
            else if (o2.startsWith("Manifest-Version:"))
            {
                return 1;
            }
            // From the "JAR File Specification":
            // Each section must start with an attribute with the name as "Name"
            else if (o1.startsWith("Name:") && !o2.startsWith("Name:"))
            {
                return -1;
            }
            else if (o2.startsWith("Name:") && !o1.startsWith("Name:"))
            {
                return 1;
            }
            else
            {
                return o1.compareTo(o2);
            }
        }
    };
    
    @Override
    public void strip(File in, File out) throws IOException
    {
        final List lines = Files.readAllLines(in.toPath(), StandardCharsets.UTF_8);
        
        try (final BufferedWriter writer = new BufferedWriter(
                new OutputStreamWriter(new FileOutputStream(out), StandardCharsets.UTF_8)))
        {
            final String sortedManifest = sortManifestSections(lines).stream()
                                            .collect(Collectors.joining("\r\n"));
            try
            {
                writer.write(sortedManifest + "\r\n");
            }
            catch (IOException e)
            {
            }
        }
    }
    
    private List sortManifestSections(List lines)
    {
        final List> sections = new ArrayList<>();
        List currentSection = new ArrayList<>();
        for (String line : lines)
        {
            // New section?
            if (line.isEmpty())
            {
                if (!currentSection.isEmpty())
                {
                    sections.add(currentSection);
                    currentSection = new ArrayList<>();
                }
            }
            else
            {
                currentSection.add(line);
            }
        }
        if (!currentSection.isEmpty())
        {
            sections.add(currentSection);
        }
        
        return sections.stream()
                        .map(list -> sortAttributes(list))
                        .map(list -> String.join("", list))
                        .sorted(MANIFEST_ENTRY_COMPARATOR)
                        .collect(Collectors.toList());
    }
    
    private List sortAttributes(List lines)
    {
        final List attributes = new ArrayList<>();
        String currentAttribute = "";
        for (String line : lines)
        {
            if (line.startsWith(" "))
            {
                currentAttribute += line + "\r\n";
            }
            else
            {
                if (!currentAttribute.isEmpty())
                {
                    attributes.add(currentAttribute);
                    currentAttribute = "";
                }
                currentAttribute = line + "\r\n";
            }
        }
        if (!currentAttribute.isEmpty())
        {
            attributes.add(currentAttribute);
        }
        attributes.sort(MANIFEST_ENTRY_COMPARATOR);
        return attributes;
    }
}