[JGIT PATCH v2 07/24] Added findWorkTree method to Repository class.

@@ -16,6 +16,11 @@
  */
 package org.spearce.jgit.lib;
 
+import static org.spearce.jgit.lib.Constants.HEAD_FILE_NAME;
+import static org.spearce.jgit.lib.Constants.OBJECTS_DIRECTORY_NAME;
+import static org.spearce.jgit.lib.Constants.REFS_DIRECTORY_NAME;
+import static org.spearce.jgit.lib.Constants.REPOSITORY_DIRECTORY_NAME;
+
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileNotFoundException;

@@ -1242,4 +1247,89 @@ public class Repository {
 		}
 	}
 
+	/**
+	 * Find the git repository for the current working directory.
+	 * 
+	 * @return a {@link Repository}.
+	 * @throws IOException
+	 *             if the system property user.dir isn't set or if it is
+	 *             invalid.
+	 */
+	public static WorkTree findWorkTree() throws IOException {
+		final String workingDirectoryPath = System.getProperty("user.dir");
+		if (workingDirectoryPath == null) {
+			throw new IOException("unable to get working directory");
+		}
+		final File workingDirectoryFile = new File(workingDirectoryPath);
+		if (!workingDirectoryFile.exists()) {
+			throw new IOException("Working directory path is invalid");
+		}
+		return findWorkTree(workingDirectoryFile);
+	}
+
+	/**
+	 * Checks if a path is a valid git repository. Works similar like the method
+	 * is_git_directory from the original setup.c file.
+	 * 
+	 * @param directory
+	 *            the path which should be checked.
+	 * @return true if the path is a valid git repository.
+	 */
+	private static boolean isRepository(File directory) {
+		if (!directory.isDirectory()) {
+			return false;
+		}
+
+		final File objectDirectory = new File(directory, OBJECTS_DIRECTORY_NAME);
+		if (!objectDirectory.isDirectory()) {
+			return false;
+		}
+
+		final File refsDirectory = new File(directory, REFS_DIRECTORY_NAME);
+		if (!refsDirectory.isDirectory()) {
+			return false;
+		}
+
+		final File head = new File(directory, HEAD_FILE_NAME);
+		if (!hasValidateHeadRef(head)) {
+			return false;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Checks for example if a path is a valid HEAD file. Should do the same
+	 * like validate_headref from path.c.
+	 * 
+	 * @param path
+	 *            is the path of the HEAD file.
+	 * @return true if it has a valid head reference.
+	 */
+	private static final boolean hasValidateHeadRef(File path) {
+		return true; // TODO stub. view int validate_headref(const char
+		// *path) at path.c
+	}
+
+	private static WorkTree findWorkTree(File directory) throws IOException {
+		File currentDirectory = directory.getAbsoluteFile();
+		while (true) {
+			final File commonGitDirectory = new File(directory,
+					REPOSITORY_DIRECTORY_NAME);
+			if (isRepository(commonGitDirectory)) {
+				return new WorkTree(currentDirectory, new Repository(
+						commonGitDirectory));
+			}
+
+			if (isRepository(currentDirectory)) {
+				return new WorkTree(null, new Repository(currentDirectory));
+			}
+			currentDirectory = currentDirectory.getParentFile();
+			if (currentDirectory == null) {
+				throw new IOException("Can't find git repository");
+			}
+		}
+
+	}
+
 }