Submodules: use relative paths for worktree and gitdir

Currently absolute paths are used for a submodules 'worktree' and
'gitdir'. This has drawbacks if a git repository containing submodules
is copied to a different location.

Enable using relative paths when creating a file-based repository. Add
optional relative path support to the clone and init commands, and use
it in the submodule commands to generate relative paths.

The new implementation mimics the cgit behavior which also uses
relative paths instead of absolute ones.

Bug: jgit-78
Change-Id: I31c5a938d5cbc030d273fc649c94ee0c90b4ce01

4 files changed, 46 insertions, 6 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/CloneCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/CloneCommand.java
index 3e034f1a6a..4a536b9534 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/CloneCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/CloneCommand.java
@@ -67,6 +67,8 @@ public class CloneCommand extends TransportCommand<CloneCommand, Git> {
 
 	private boolean bare;
 
+	private boolean relativePaths;
+
 	private FS fs;
 
 	private String remote = Constants.DEFAULT_REMOTE_NAME;
@@ -264,6 +266,7 @@ public class CloneCommand extends TransportCommand<CloneCommand, Git> {
 	private Repository init() throws GitAPIException {
 		InitCommand command = Git.init();
 		command.setBare(bare);
+		command.setRelativeDirs(relativePaths);
 		if (fs != null) {
 			command.setFs(fs);
 		}
@@ -555,6 +558,20 @@ public class CloneCommand extends TransportCommand<CloneCommand, Git> {
 	}
 
 	/**
+	 * Set whether the cloned repository shall use relative paths for GIT_DIR
+	 * and GIT_WORK_TREE
+	 *
+	 * @param relativePaths
+	 *            if true, use relative paths for GIT_DIR and GIT_WORK_TREE
+	 * @return this instance
+	 * @since 7.2
+	 */
+	public CloneCommand setRelativePaths(boolean relativePaths) {
+		this.relativePaths = relativePaths;
+		return this;
+	}
+
+	/**
 	 * Set the file system abstraction to be used for repositories created by
 	 * this command.
 	 *
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/InitCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/InitCommand.java
index 240290f4f9..1da71aa6eb 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/InitCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/InitCommand.java
@@ -19,6 +19,7 @@ import org.eclipse.jgit.api.errors.InvalidRefNameException;
 import org.eclipse.jgit.api.errors.JGitInternalException;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.internal.JGitText;
+import org.eclipse.jgit.internal.storage.file.FileRepository;
 import org.eclipse.jgit.lib.ConfigConstants;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.Repository;
@@ -44,6 +45,8 @@ public class InitCommand implements Callable<Git> {
 
 	private String initialBranch;
 
+	private boolean relativePaths;
+
 	/**
 	 * {@inheritDoc}
 	 * <p>
@@ -100,7 +103,11 @@ public class InitCommand implements Callable<Git> {
 					: initialBranch);
 			Repository repository = builder.build();
 			if (!repository.getObjectDatabase().exists())
-				repository.create(bare);
+				if (repository instanceof FileRepository) {
+					((FileRepository) repository).create(bare, relativePaths);
+				} else {
+					repository.create(bare);
+				}
 			return new Git(repository, true);
 		} catch (IOException | ConfigInvalidException e) {
 			throw new JGitInternalException(e.getMessage(), e);
@@ -214,4 +221,18 @@ public class InitCommand implements Callable<Git> {
 		this.initialBranch = branch;
 		return this;
 	}
+
+	/**
+	 * * Set whether the repository shall use relative paths for GIT_DIR and
+	 * GIT_WORK_TREE
+	 *
+	 * @param relativePaths
+	 *            if true, use relative paths for GIT_DIR and GIT_WORK_TREE
+	 * @return {@code this}
+	 * @since 7.2
+	 */
+	public InitCommand setRelativeDirs(boolean relativePaths) {
+		this.relativePaths = relativePaths;
+		return this;
+	}
 }
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleAddCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleAddCommand.java
index 401f069e4e..5105dfc2e5 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleAddCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleAddCommand.java
@@ -176,8 +176,9 @@ public class SubmoduleAddCommand extends
 		CloneCommand clone = Git.cloneRepository();
 		configure(clone);
 		clone.setDirectory(moduleDirectory);
-		clone.setGitDir(new File(new File(repo.getCommonDirectory(),
-				Constants.MODULES), path));
+		clone.setGitDir(new File(
+				new File(repo.getCommonDirectory(), Constants.MODULES), path));
+		clone.setRelativePaths(true);
 		clone.setURI(resolvedUri);
 		if (monitor != null)
 			clone.setProgressMonitor(monitor);
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleUpdateCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleUpdateCommand.java
index 751dabcd6b..3524984347 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleUpdateCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleUpdateCommand.java
@@ -127,9 +127,10 @@ public class SubmoduleUpdateCommand extends
 			configure(clone);
 			clone.setURI(url);
 			clone.setDirectory(generator.getDirectory());
-			clone.setGitDir(
-					new File(new File(repo.getCommonDirectory(), Constants.MODULES),
-							generator.getPath()));
+			clone.setGitDir(new File(
+					new File(repo.getCommonDirectory(), Constants.MODULES),
+					generator.getPath()));
+			clone.setRelativePaths(true);
 			if (monitor != null) {
 				clone.setProgressMonitor(monitor);
 			}