[PATCH 6/7] clone: introduce clone.submodulegitdir

[Ramkumar Ramachandra <artagnon@gmail.com>]

This configuration variable comes into effect when 'git clone' is
invoked in an existing git repository.  Instead of cloning the
repository as-is, it relocates the gitdir of the repository to the
path specified by this variable.  Arguably, it does the right thing
when working with submodules.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 builtin/clone.c | 29 +++++++++++++++++++++++++++++
 environment.c   | 11 -----------
 2 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/builtin/clone.c b/builtin/clone.c
index e0aaf13..1b798e6 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -43,6 +43,7 @@ static char *option_template, *option_depth;
 static char *option_origin = NULL;
 static char *option_branch = NULL;
 static const char *real_git_dir;
+static const char *submodule_gitdir;
 static char *option_upload_pack = "git-upload-pack";
 static int option_verbosity;
 static int option_progress = -1;
@@ -658,11 +659,22 @@ static void write_refspec_config(const char* src_ref_prefix,
 	strbuf_release(&value);
 }
 
+static int git_clone_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "clone.submodulegitdir")) {
+		git_config_string(&submodule_gitdir, var, value);
+		return 0;
+	}
+	return git_default_config(var, value, cb);
+}
+
 int cmd_clone(int argc, const char **argv, const char *prefix)
 {
 	int is_bundle = 0, is_local;
 	struct stat buf;
 	const char *repo_name, *repo, *work_tree, *git_dir;
+	char dest_git_dir[PATH_MAX];
+	char cwd[PATH_MAX];
 	char *path, *dir;
 	int dest_exists;
 	const struct ref *refs, *remote_head;
@@ -676,6 +688,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	const char *src_ref_prefix = "refs/heads/";
 	struct remote *remote;
 	int err = 0, complete_refs_before_fetch = 1;
+	int nongit = 1;
 
 	struct refspec *refspec;
 	const char *fetch_pattern;
@@ -683,6 +696,14 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	junk_pid = getpid();
 
 	packet_trace_identity("clone");
+
+	/* setup_git_directory_gently without changing directories */
+	getcwd(cwd, sizeof(cwd) - 1);
+	setup_git_directory_gently(&nongit);
+	chdir(cwd);
+
+	git_config(git_clone_config, NULL);
+
 	argc = parse_options(argc, argv, prefix, builtin_clone_options,
 			     builtin_clone_usage, 0);
 
@@ -736,6 +757,14 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 		die(_("destination path '%s' already exists and is not "
 			"an empty directory."), dir);
 
+	if (!nongit && submodule_gitdir) {
+		sprintf(dest_git_dir, "%s/%s.git", real_path(submodule_gitdir), dir);
+		if (!stat(dest_git_dir, &buf) && !is_empty_dir(dest_git_dir))
+			die(_("destination path '%s' already exists and is not "
+					"an empty directory."), dest_git_dir);
+		real_git_dir = dest_git_dir;
+	}
+
 	strbuf_addf(&reflog_msg, "clone: from %s", repo);
 
 	if (option_bare)
diff --git a/environment.c b/environment.c
index e2e75c1..9dce4c7 100644
--- a/environment.c
+++ b/environment.c
@@ -182,8 +182,6 @@ const char *strip_namespace(const char *namespaced_ref)
 	return namespaced_ref + namespace_len;
 }
 
-static int git_work_tree_initialized;
-
 /*
  * Note.  This works only before you used a work tree.  This was added
  * primarily to support git-clone to work in a new repository it just
@@ -191,15 +189,6 @@ static int git_work_tree_initialized;
  */
 void set_git_work_tree(const char *new_work_tree)
 {
-	if (git_work_tree_initialized) {
-		new_work_tree = real_path(new_work_tree);
-		if (strcmp(new_work_tree, work_tree))
-			die("internal error: work tree has already been set\n"
-			    "Current worktree: %s\nNew worktree: %s",
-			    work_tree, new_work_tree);
-		return;
-	}
-	git_work_tree_initialized = 1;
 	work_tree = xstrdup(real_path(new_work_tree));
 }
 
-- 
1.8.2.380.g0d4e79b