getdown/src/main/java/com/threerings/getdown/util/FileUtil.java

//
// Getdown - application installer, patcher and launcher
// Copyright (C) 2004-2016 Getdown authors
// https://github.com/threerings/getdown/blob/master/LICENSE

package com.threerings.getdown.util;

import java.io.*;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Deque;
import java.util.Enumeration;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.JarOutputStream;
import java.util.jar.Pack200;
import java.util.zip.GZIPInputStream;

import com.samskivert.io.StreamUtil;
import com.samskivert.util.Logger;

import static com.threerings.getdown.Log.log;

/**
 * File related utilities.
 */
public class FileUtil
{
    /**
     * Gets the specified source file to the specified destination file by hook or crook. Windows
     * has all sorts of problems which we work around in this method.
     *
     * @return true if we managed to get the job done, false otherwise.
     */
    public static boolean renameTo (File source, File dest)
    {
        // if we're on a civilized operating system we may be able to simple rename it
        if (source.renameTo(dest)) {
            return true;
        }

        // fall back to trying to rename the old file out of the way, rename the new file into
        // place and then delete the old file
        if (dest.exists()) {
            File temp = new File(dest.getPath() + "_old");
            if (temp.exists() && !deleteHarder(temp)) {
                log.warning("Failed to delete old intermediate file " + temp + ".");
                // the subsequent code will probably fail
            }
            if (dest.renameTo(temp) && source.renameTo(dest)) {
                if (!deleteHarder(temp)) {
                    log.warning("Failed to delete intermediate file " + temp + ".");
                }
                return true;
            }
        }

        // as a last resort, try copying the old data over the new
        FileInputStream fin = null;
        FileOutputStream fout = null;
        try {
            fin = new FileInputStream(source);
            fout = new FileOutputStream(dest);
            StreamUtil.copy(fin, fout);
            // close the input stream now so we can delete 'source'
            fin.close();
            fin = null;
            if (!deleteHarder(source)) {
                log.warning("Failed to delete " + source +
                            " after brute force copy to " + dest + ".");
            }
            return true;

        } catch (IOException ioe) {
            log.warning("Failed to copy " + source + " to " + dest + ": " + ioe);
            return false;

        } finally {
            StreamUtil.close(fin);
            StreamUtil.close(fout);
        }
    }

    /**
     * "Tries harder" to delete {@code file} than just calling {@code delete} on it. Presently this
     * just means "try a second time if the first time fails." On Windows Vista, sometimes deletes
     * fail but then succeed if you just try again. Given that delete failure is a rare occurance,
     * we can implement this hacky workaround without any negative consequences for normal
     * behavior.
     */
    public static boolean deleteHarder (File file) {
        // if at first you don't succeed... try, try again
        return file.delete() || file.delete();
    }

    /**
     * Reads the contents of the supplied input stream into a list of lines. Closes the reader on
     * successful or failed completion.
     */
    public static List<String> readLines (Reader in)
        throws IOException
    {
        List<String> lines = new ArrayList<>();
        try {
            BufferedReader bin = new BufferedReader(in);
            for (String line = null; (line = bin.readLine()) != null; lines.add(line)) {}
        } finally {
            StreamUtil.close(in);
        }
        return lines;
    }

    /**
     * Unpacks the specified jar file intto the specified target directory.
     */
    public static void unpackJar (JarFile jar, File target) throws IOException
    {
        try {
            Enumeration<?> entries = jar.entries();
            while (entries.hasMoreElements()) {
                JarEntry entry = (JarEntry)entries.nextElement();
                File efile = new File(target, entry.getName());

                // if we're unpacking a normal jar file, it will have special path
                // entries that allow us to create our directories first
                if (entry.isDirectory()) {
                    if (!efile.exists() && !efile.mkdir()) {
                        log.warning("Failed to create jar entry path", "jar", jar, "entry", entry);
                    }
                    continue;
                }

                // but some do not, so we want to ensure that our directories exist
                // prior to getting down and funky
                File parent = new File(efile.getParent());
                if (!parent.exists() && !parent.mkdirs()) {
                    log.warning("Failed to create jar entry parent", "jar", jar, "parent", parent);
                    continue;
                }

                BufferedOutputStream fout = null;
                InputStream jin = null;
                try {
                    fout = new BufferedOutputStream(new FileOutputStream(efile));
                    jin = jar.getInputStream(entry);
                    StreamUtil.copy(jin, fout);
                } catch (Exception e) {
                    throw new IOException(
                        Logger.format("Failure unpacking", "jar", jar, "entry", efile), e);
                } finally {
                    StreamUtil.close(jin);
                    StreamUtil.close(fout);
                }
            }

        } finally {
            try {
                jar.close();
            } catch (Exception e) {
                log.warning("Failed to close jar file", "jar", jar, "error", e);
            }
        }
    }

    /**
     * Unpacks a pack200 packed jar file from {@code packedJar} into {@code target}. If {@code
     * packedJar} has a {@code .gz} extension, it will be gunzipped first.
     */
    public static void unpackPacked200Jar (File packedJar, File target) throws IOException
    {
        InputStream packedJarIn = null;
        FileOutputStream extractedJarFileOut = null;
        JarOutputStream jarOutputStream = null;
        try {
            extractedJarFileOut = new FileOutputStream(target);
            jarOutputStream = new JarOutputStream(extractedJarFileOut);
            packedJarIn = new FileInputStream(packedJar);
            if (packedJar.getName().endsWith(".gz") || packedJar.getName().endsWith(".gz_new")) {
                packedJarIn = new GZIPInputStream(packedJarIn);
            }
            Pack200.Unpacker unpacker = Pack200.newUnpacker();
            unpacker.unpack(packedJarIn, jarOutputStream);

        } finally {
            StreamUtil.close(jarOutputStream);
            StreamUtil.close(extractedJarFileOut);
            StreamUtil.close(packedJarIn);
        }
    }

    /**
     * Copies the given {@code source} file to the given {@code target}.
     */
    public static void copy (File source, File target) throws IOException {
        FileInputStream in = null;
        FileOutputStream out = null;
        try {
            in = new FileInputStream(source);
            out = new FileOutputStream(target);
            StreamUtil.copy(in, out);
        } finally {
            StreamUtil.close(in);
            StreamUtil.close(out);
        }
    }

    /**
     * Used by {@link #walkTree}.
     */
    public interface Visitor
    {
        void visit (File file);
    }

    /**
     * Walks all files in {@code root}, calling {@code visitor} on each file in the tree.
     */
    public static void walkTree (File root, Visitor visitor)
    {
        Deque<File> stack = new ArrayDeque<>(Arrays.asList(root.listFiles()));
        while (!stack.isEmpty()) {
            File currentFile = stack.pop();
            if (currentFile.exists()) {
                visitor.visit(currentFile);
                if (currentFile.isDirectory()) {
                    for (File file: currentFile.listFiles()) {
                        stack.push(file);
                    }
                }
            }
        }
    }
}