/*
    * Copyright (C) 2010, Google Inc.
    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
    * available at http://www.eclipse.org/org/documents/edl-v10.php
    *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - Redistributions in binary form must reproduce the above
   *   copyright notice, this list of conditions and the following
   *   disclaimer in the documentation and/or other materials provided
   *   with the distribution.
   *
   * - Neither the name of the Eclipse Foundation, Inc. nor the
   *   names of its contributors may be used to endorse or promote
   *   products derived from this software without specific prior
   *   written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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  package org.eclipse.jgit.lib;
  
  import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_CORE_SECTION;
  import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_BARE;
  import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_WORKTREE;
  import static org.eclipse.jgit.lib.Constants.DOT_GIT;
  import static org.eclipse.jgit.lib.Constants.GIT_ALTERNATE_OBJECT_DIRECTORIES_KEY;
  import static org.eclipse.jgit.lib.Constants.GIT_CEILING_DIRECTORIES_KEY;
  import static org.eclipse.jgit.lib.Constants.GIT_DIR_KEY;
  import static org.eclipse.jgit.lib.Constants.GIT_INDEX_FILE_KEY;
  import static org.eclipse.jgit.lib.Constants.GIT_OBJECT_DIRECTORY_KEY;
  import static org.eclipse.jgit.lib.Constants.GIT_WORK_TREE_KEY;
  
  import java.io.File;
  import java.io.IOException;
  import java.text.MessageFormat;
  import java.util.Collection;
  import java.util.LinkedList;
  import java.util.List;
  
  import org.eclipse.jgit.errors.ConfigInvalidException;
  import org.eclipse.jgit.errors.RepositoryNotFoundException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.internal.storage.file.FileRepository;
  import org.eclipse.jgit.lib.RepositoryCache.FileKey;
  import org.eclipse.jgit.storage.file.FileBasedConfig;
  import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
  import org.eclipse.jgit.util.FS;
  import org.eclipse.jgit.util.IO;
  import org.eclipse.jgit.util.RawParseUtils;
  import org.eclipse.jgit.util.SystemReader;
  
  /**
   * Base builder to customize repository construction.
   * <p>
   * Repository implementations may subclass this builder in order to add custom
   * repository detection methods.
   *
   * @param <B>
   *            type of the repository builder.
   * @param <R>
   *            type of the repository that is constructed.
   * @see RepositoryBuilder
   * @see FileRepositoryBuilder
   */
  public class BaseRepositoryBuilder<B extends BaseRepositoryBuilder, R extends Repository> {
  	private static boolean isSymRef(byte[] ref) {
  		if (ref.length < 9)
  			return false;
  		return /**/ref[0] == 'g' //
  				&& ref[1] == 'i' //
  				&& ref[2] == 't' //
  				&& ref[3] == 'd' //
  				&& ref[4] == 'i' //
  				&& ref[5] == 'r' //
  				&& ref[6] == ':' //
 				&& ref[7] == ' ';
 	}
 
 	private static File getSymRef(File workTree, File dotGit, FS fs)
 			throws IOException {
 		byte[] content = IO.readFully(dotGit);
 		if (!isSymRef(content))
 			throw new IOException(MessageFormat.format(
 					JGitText.get().invalidGitdirRef, dotGit.getAbsolutePath()));
 
 		int pathStart = 8;
 		int lineEnd = RawParseUtils.nextLF(content, pathStart);
 		if (content[lineEnd - 1] == '\n')
 			lineEnd--;
 		if (lineEnd == pathStart)
 			throw new IOException(MessageFormat.format(
 					JGitText.get().invalidGitdirRef, dotGit.getAbsolutePath()));
 
 		String gitdirPath = RawParseUtils.decode(content, pathStart, lineEnd);
 		File gitdirFile = fs.resolve(workTree, gitdirPath);
 		if (gitdirFile.isAbsolute())
 			return gitdirFile;
 		else
 			return new File(workTree, gitdirPath).getCanonicalFile();
 	}
 
 	private FS fs;
 
 	private File gitDir;
 
 	private File objectDirectory;
 
 	private List<File> alternateObjectDirectories;
 
 	private File indexFile;
 
 	private File workTree;
 
 	/** Directories limiting the search for a Git repository. */
 	private List<File> ceilingDirectories;
 
 	/** True only if the caller wants to force bare behavior. */
 	private boolean bare;
 
 	/** True if the caller requires the repository to exist. */
 	private boolean mustExist;
 
 	/** Configuration file of target repository, lazily loaded if required. */
 	private Config config;
 
 	/**
 	 * Set the file system abstraction needed by this repository.
 	 *
 	 * @param fs
 	 *            the abstraction.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B setFS(FS fs) {
 		this.fs = fs;
 		return self();
 	}
 
 	/** @return the file system abstraction, or null if not set. */
 	public FS getFS() {
 		return fs;
 	}
 
 	/**
 	 * Set the Git directory storing the repository metadata.
 	 * <p>
 	 * The meta directory stores the objects, references, and meta files like
 	 * {@code MERGE_HEAD}, or the index file. If {@code null} the path is
 	 * assumed to be {@code workTree/.git}.
 	 *
 	 * @param gitDir
 	 *            {@code GIT_DIR}, the repository meta directory.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B setGitDir(File gitDir) {
 		this.gitDir = gitDir;
 		this.config = null;
 		return self();
 	}
 
 	/** @return the meta data directory; null if not set. */
 	public File getGitDir() {
 		return gitDir;
 	}
 
 	/**
 	 * Set the directory storing the repository's objects.
 	 *
 	 * @param objectDirectory
 	 *            {@code GIT_OBJECT_DIRECTORY}, the directory where the
 	 *            repository's object files are stored.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B setObjectDirectory(File objectDirectory) {
 		this.objectDirectory = objectDirectory;
 		return self();
 	}
 
 	/** @return the object directory; null if not set. */
 	public File getObjectDirectory() {
 		return objectDirectory;
 	}
 
 	/**
 	 * Add an alternate object directory to the search list.
 	 * <p>
 	 * This setting handles one alternate directory at a time, and is provided
 	 * to support {@code GIT_ALTERNATE_OBJECT_DIRECTORIES}.
 	 *
 	 * @param other
 	 *            another objects directory to search after the standard one.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B addAlternateObjectDirectory(File other) {
 		if (other != null) {
 			if (alternateObjectDirectories == null)
 				alternateObjectDirectories = new LinkedList<File>();
 			alternateObjectDirectories.add(other);
 		}
 		return self();
 	}
 
 	/**
 	 * Add alternate object directories to the search list.
 	 * <p>
 	 * This setting handles several alternate directories at once, and is
 	 * provided to support {@code GIT_ALTERNATE_OBJECT_DIRECTORIES}.
 	 *
 	 * @param inList
 	 *            other object directories to search after the standard one. The
 	 *            collection's contents is copied to an internal list.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B addAlternateObjectDirectories(Collection<File> inList) {
 		if (inList != null) {
 			for (File path : inList)
 				addAlternateObjectDirectory(path);
 		}
 		return self();
 	}
 
 	/**
 	 * Add alternate object directories to the search list.
 	 * <p>
 	 * This setting handles several alternate directories at once, and is
 	 * provided to support {@code GIT_ALTERNATE_OBJECT_DIRECTORIES}.
 	 *
 	 * @param inList
 	 *            other object directories to search after the standard one. The
 	 *            array's contents is copied to an internal list.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B addAlternateObjectDirectories(File[] inList) {
 		if (inList != null) {
 			for (File path : inList)
 				addAlternateObjectDirectory(path);
 		}
 		return self();
 	}
 
 	/** @return ordered array of alternate directories; null if non were set. */
 	public File[] getAlternateObjectDirectories() {
 		final List<File> alts = alternateObjectDirectories;
 		if (alts == null)
 			return null;
 		return alts.toArray(new File[alts.size()]);
 	}
 
 	/**
 	 * Force the repository to be treated as bare (have no working directory).
 	 * <p>
 	 * If bare the working directory aspects of the repository won't be
 	 * configured, and will not be accessible.
 	 *
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B setBare() {
 		setIndexFile(null);
 		setWorkTree(null);
 		bare = true;
 		return self();
 	}
 
 	/** @return true if this repository was forced bare by {@link #setBare()}. */
 	public boolean isBare() {
 		return bare;
 	}
 
 	/**
 	 * Require the repository to exist before it can be opened.
 	 *
 	 * @param mustExist
 	 *            true if it must exist; false if it can be missing and created
 	 *            after being built.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B setMustExist(boolean mustExist) {
 		this.mustExist = mustExist;
 		return self();
 	}
 
 	/** @return true if the repository must exist before being opened. */
 	public boolean isMustExist() {
 		return mustExist;
 	}
 
 	/**
 	 * Set the top level directory of the working files.
 	 *
 	 * @param workTree
 	 *            {@code GIT_WORK_TREE}, the working directory of the checkout.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B setWorkTree(File workTree) {
 		this.workTree = workTree;
 		return self();
 	}
 
 	/** @return the work tree directory, or null if not set. */
 	public File getWorkTree() {
 		return workTree;
 	}
 
 	/**
 	 * Set the local index file that is caching checked out file status.
 	 * <p>
 	 * The location of the index file tracking the status information for each
 	 * checked out file in {@code workTree}. This may be null to assume the
 	 * default {@code gitDiir/index}.
 	 *
 	 * @param indexFile
 	 *            {@code GIT_INDEX_FILE}, the index file location.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B setIndexFile(File indexFile) {
 		this.indexFile = indexFile;
 		return self();
 	}
 
 	/** @return the index file location, or null if not set. */
 	public File getIndexFile() {
 		return indexFile;
 	}
 
 	/**
 	 * Read standard Git environment variables and configure from those.
 	 * <p>
 	 * This method tries to read the standard Git environment variables, such as
 	 * {@code GIT_DIR} and {@code GIT_WORK_TREE} to configure this builder
 	 * instance. If an environment variable is set, it overrides the value
 	 * already set in this builder.
 	 *
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B readEnvironment() {
 		return readEnvironment(SystemReader.getInstance());
 	}
 
 	/**
 	 * Read standard Git environment variables and configure from those.
 	 * <p>
 	 * This method tries to read the standard Git environment variables, such as
 	 * {@code GIT_DIR} and {@code GIT_WORK_TREE} to configure this builder
 	 * instance. If a property is already set in the builder, the environment
 	 * variable is not used.
 	 *
 	 * @param sr
 	 *            the SystemReader abstraction to access the environment.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B readEnvironment(SystemReader sr) {
 		if (getGitDir() == null) {
 			String val = sr.getenv(GIT_DIR_KEY);
 			if (val != null)
 				setGitDir(new File(val));
 		}
 
 		if (getObjectDirectory() == null) {
 			String val = sr.getenv(GIT_OBJECT_DIRECTORY_KEY);
 			if (val != null)
 				setObjectDirectory(new File(val));
 		}
 
 		if (getAlternateObjectDirectories() == null) {
 			String val = sr.getenv(GIT_ALTERNATE_OBJECT_DIRECTORIES_KEY);
 			if (val != null) {
 				for (String path : val.split(File.pathSeparator))
 					addAlternateObjectDirectory(new File(path));
 			}
 		}
 
 		if (getWorkTree() == null) {
 			String val = sr.getenv(GIT_WORK_TREE_KEY);
 			if (val != null)
 				setWorkTree(new File(val));
 		}
 
 		if (getIndexFile() == null) {
 			String val = sr.getenv(GIT_INDEX_FILE_KEY);
 			if (val != null)
 				setIndexFile(new File(val));
 		}
 
 		if (ceilingDirectories == null) {
 			String val = sr.getenv(GIT_CEILING_DIRECTORIES_KEY);
 			if (val != null) {
 				for (String path : val.split(File.pathSeparator))
 					addCeilingDirectory(new File(path));
 			}
 		}
 
 		return self();
 	}
 
 	/**
 	 * Add a ceiling directory to the search limit list.
 	 * <p>
 	 * This setting handles one ceiling directory at a time, and is provided to
 	 * support {@code GIT_CEILING_DIRECTORIES}.
 	 *
 	 * @param root
 	 *            a path to stop searching at; its parent will not be searched.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B addCeilingDirectory(File root) {
 		if (root != null) {
 			if (ceilingDirectories == null)
 				ceilingDirectories = new LinkedList<File>();
 			ceilingDirectories.add(root);
 		}
 		return self();
 	}
 
 	/**
 	 * Add ceiling directories to the search list.
 	 * <p>
 	 * This setting handles several ceiling directories at once, and is provided
 	 * to support {@code GIT_CEILING_DIRECTORIES}.
 	 *
 	 * @param inList
 	 *            directory paths to stop searching at. The collection's
 	 *            contents is copied to an internal list.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B addCeilingDirectories(Collection<File> inList) {
 		if (inList != null) {
 			for (File path : inList)
 				addCeilingDirectory(path);
 		}
 		return self();
 	}
 
 	/**
 	 * Add ceiling directories to the search list.
 	 * <p>
 	 * This setting handles several ceiling directories at once, and is provided
 	 * to support {@code GIT_CEILING_DIRECTORIES}.
 	 *
 	 * @param inList
 	 *            directory paths to stop searching at. The array's contents is
 	 *            copied to an internal list.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B addCeilingDirectories(File[] inList) {
 		if (inList != null) {
 			for (File path : inList)
 				addCeilingDirectory(path);
 		}
 		return self();
 	}
 
 	/**
 	 * Configure {@code GIT_DIR} by searching up the file system.
 	 * <p>
 	 * Starts from the current working directory of the JVM and scans up through
 	 * the directory tree until a Git repository is found. Success can be
 	 * determined by checking for {@code getGitDir() != null}.
 	 * <p>
 	 * The search can be limited to specific spaces of the local filesystem by
 	 * {@link #addCeilingDirectory(File)}, or inheriting the list through a
 	 * prior call to {@link #readEnvironment()}.
 	 *
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B findGitDir() {
 		if (getGitDir() == null)
 			findGitDir(new File("").getAbsoluteFile()); //$NON-NLS-1$
 		return self();
 	}
 
 	/**
 	 * Configure {@code GIT_DIR} by searching up the file system.
 	 * <p>
 	 * Starts from the supplied directory path and scans up through the parent
 	 * directory tree until a Git repository is found. Success can be determined
 	 * by checking for {@code getGitDir() != null}.
 	 * <p>
 	 * The search can be limited to specific spaces of the local filesystem by
 	 * {@link #addCeilingDirectory(File)}, or inheriting the list through a
 	 * prior call to {@link #readEnvironment()}.
 	 *
 	 * @param current
 	 *            directory to begin searching in.
 	 * @return {@code this} (for chaining calls).
 	 */
 	public B findGitDir(File current) {
 		if (getGitDir() == null) {
 			FS tryFS = safeFS();
 			while (current != null) {
 				File dir = new File(current, DOT_GIT);
 				if (FileKey.isGitRepository(dir, tryFS)) {
 					setGitDir(dir);
 					break;
 				} else if (dir.isFile()) {
 					try {
 						setGitDir(getSymRef(current, dir, tryFS));
 						break;
 					} catch (IOException ignored) {
 						// Continue searching if gitdir ref isn't found
 					}
 				} else if (FileKey.isGitRepository(current, tryFS)) {
 					setGitDir(current);
 					break;
 				}
 
 				current = current.getParentFile();
 				if (current != null && ceilingDirectories != null
 						&& ceilingDirectories.contains(current))
 					break;
 			}
 		}
 		return self();
 	}
 
 	/**
 	 * Guess and populate all parameters not already defined.
 	 * <p>
 	 * If an option was not set, the setup method will try to default the option
 	 * based on other options. If insufficient information is available, an
 	 * exception is thrown to the caller.
 	 *
 	 * @return {@code this}
 	 * @throws IllegalArgumentException
 	 *             insufficient parameters were set, or some parameters are
 	 *             incompatible with one another.
 	 * @throws IOException
 	 *             the repository could not be accessed to configure the rest of
 	 *             the builder's parameters.
 	 */
 	public B setup() throws IllegalArgumentException, IOException {
 		requireGitDirOrWorkTree();
 		setupGitDir();
 		setupWorkTree();
 		setupInternals();
 		return self();
 	}
 
 	/**
 	 * Create a repository matching the configuration in this builder.
 	 * <p>
 	 * If an option was not set, the build method will try to default the option
 	 * based on other options. If insufficient information is available, an
 	 * exception is thrown to the caller.
 	 *
 	 * @return a repository matching this configuration. The caller is
 	 *         responsible to close the repository instance when it is no longer
 	 *         needed.
 	 * @throws IllegalArgumentException
 	 *             insufficient parameters were set.
 	 * @throws IOException
 	 *             the repository could not be accessed to configure the rest of
 	 *             the builder's parameters.
 	 */
 	@SuppressWarnings({ "unchecked", "resource" })
 	public R build() throws IOException {
 		R repo = (R) new FileRepository(setup());
 		if (isMustExist() && !repo.getObjectDatabase().exists())
 			throw new RepositoryNotFoundException(getGitDir());
 		return repo;
 	}
 
 	/** Require either {@code gitDir} or {@code workTree} to be set. */
 	protected void requireGitDirOrWorkTree() {
 		if (getGitDir() == null && getWorkTree() == null)
 			throw new IllegalArgumentException(
 					JGitText.get().eitherGitDirOrWorkTreeRequired);
 	}
 
 	/**
 	 * Perform standard gitDir initialization.
 	 *
 	 * @throws IOException
 	 *             the repository could not be accessed
 	 */
 	protected void setupGitDir() throws IOException {
 		// No gitDir? Try to assume its under the workTree or a ref to another
 		// location
 		if (getGitDir() == null && getWorkTree() != null) {
 			File dotGit = new File(getWorkTree(), DOT_GIT);
 			if (!dotGit.isFile())
 				setGitDir(dotGit);
 			else
 				setGitDir(getSymRef(getWorkTree(), dotGit, safeFS()));
 		}
 	}
 
 	/**
 	 * Perform standard work-tree initialization.
 	 * <p>
 	 * This is a method typically invoked inside of {@link #setup()}, near the
 	 * end after the repository has been identified and its configuration is
 	 * available for inspection.
 	 *
 	 * @throws IOException
 	 *             the repository configuration could not be read.
 	 */
 	protected void setupWorkTree() throws IOException {
 		if (getFS() == null)
 			setFS(FS.DETECTED);
 
 		// If we aren't bare, we should have a work tree.
 		//
 		if (!isBare() && getWorkTree() == null)
 			setWorkTree(guessWorkTreeOrFail());
 
 		if (!isBare()) {
 			// If after guessing we're still not bare, we must have
 			// a metadata directory to hold the repository. Assume
 			// its at the work tree.
 			//
 			if (getGitDir() == null)
 				setGitDir(getWorkTree().getParentFile());
 			if (getIndexFile() == null)
 				setIndexFile(new File(getGitDir(), "index")); //$NON-NLS-1$
 		}
 	}
 
 	/**
 	 * Configure the internal implementation details of the repository.
 	 *
 	 * @throws IOException
 	 *             the repository could not be accessed
 	 */
 	protected void setupInternals() throws IOException {
 		if (getObjectDirectory() == null && getGitDir() != null)
 			setObjectDirectory(safeFS().resolve(getGitDir(), "objects")); //$NON-NLS-1$
 	}
 
 	/**
 	 * Get the cached repository configuration, loading if not yet available.
 	 *
 	 * @return the configuration of the repository.
 	 * @throws IOException
 	 *             the configuration is not available, or is badly formed.
 	 */
 	protected Config getConfig() throws IOException {
 		if (config == null)
 			config = loadConfig();
 		return config;
 	}
 
 	/**
 	 * Parse and load the repository specific configuration.
 	 * <p>
 	 * The default implementation reads {@code gitDir/config}, or returns an
 	 * empty configuration if gitDir was not set.
 	 *
 	 * @return the repository's configuration.
 	 * @throws IOException
 	 *             the configuration is not available.
 	 */
 	protected Config loadConfig() throws IOException {
 		if (getGitDir() != null) {
 			// We only want the repository's configuration file, and not
 			// the user file, as these parameters must be unique to this
 			// repository and not inherited from other files.
 			//
 			File path = safeFS().resolve(getGitDir(), Constants.CONFIG);
 			FileBasedConfig cfg = new FileBasedConfig(path, safeFS());
 			try {
 				cfg.load();
 			} catch (ConfigInvalidException err) {
 				throw new IllegalArgumentException(MessageFormat.format(
 						JGitText.get().repositoryConfigFileInvalid, path
 								.getAbsolutePath(), err.getMessage()));
 			}
 			return cfg;
 		} else {
 			return new Config();
 		}
 	}
 
 	private File guessWorkTreeOrFail() throws IOException {
 		final Config cfg = getConfig();
 
 		// If set, core.worktree wins.
 		//
 		String path = cfg.getString(CONFIG_CORE_SECTION, null,
 				CONFIG_KEY_WORKTREE);
 		if (path != null)
 			return safeFS().resolve(getGitDir(), path).getCanonicalFile();
 
 		// If core.bare is set, honor its value. Assume workTree is
 		// the parent directory of the repository.
 		//
 		if (cfg.getString(CONFIG_CORE_SECTION, null, CONFIG_KEY_BARE) != null) {
 			if (cfg.getBoolean(CONFIG_CORE_SECTION, CONFIG_KEY_BARE, true)) {
 				setBare();
 				return null;
 			}
 			return getGitDir().getParentFile();
 		}
 
 		if (getGitDir().getName().equals(DOT_GIT)) {
 			// No value for the "bare" flag, but gitDir is named ".git",
 			// use the parent of the directory
 			//
 			return getGitDir().getParentFile();
 		}
 
 		// We have to assume we are bare.
 		//
 		setBare();
 		return null;
 	}
 
 	/** @return the configured FS, or {@link FS#DETECTED}. */
 	protected FS safeFS() {
 		return getFS() != null ? getFS() : FS.DETECTED;
 	}
 
 	/** @return {@code this} */
 	@SuppressWarnings("unchecked")
 	protected final B self() {
 		return (B) this;
 	}
 }