branch: add git_branch_move()

include/git2/branch.h

@@ -95,6 +95,28 @@ GIT_EXTERN(int) git_branch_list(
 		git_repository *repo,
 		unsigned int list_flags);
 
+/**
+ * Move/rename an existing branch reference.
+ *
+ * @param repo Repository where lives the branch.
+ *
+ * @param old_branch_name Current name of the branch to be moved;
+ * this name is validated for consistency.
+ *
+ * @param new_branch_name Target name of the branch once the move
+ * is performed; this name is validated for consistency.
+ *
+ * @param force Overwrite existing branch.
+ *
+ * @return GIT_SUCCESS on success, GIT_ENOTFOUND if the branch
+ * doesn't exist or an error code.
+ */
+GIT_EXTERN(int) git_branch_move(
+		git_repository *repo,
+		const char *old_branch_name,
+		const char *new_branch_name,
+		int force);
+
 /** @} */
 GIT_END_DECL
 #endif

src/branch.c

@@ -178,3 +178,21 @@ int git_branch_list(git_strarray *branch_names, git_repository *repo, unsigned i
 	branch_names->count = branchlist.length;
 	return 0;
 }
+
+int git_branch_move(git_repository *repo, const char *old_branch_name, const char *new_branch_name, int force)
+{
+	git_reference *reference;
+	git_buf old_reference_name = GIT_BUF_INIT, new_reference_name = GIT_BUF_INIT;
+	int error;
+
+	if (git_buf_joinpath(&old_reference_name, GIT_REFS_HEADS_DIR, old_branch_name) < 0)
+		return -1;
+
+	if (git_buf_joinpath(&new_reference_name, GIT_REFS_HEADS_DIR, new_branch_name) < 0)
+		return -1;
+
+	if ((error = git_reference_lookup(&reference, repo, git_buf_cstr(&old_reference_name))) < 0)
+		return error;
+
+	return git_reference_rename(reference, git_buf_cstr(&new_reference_name), force);
+}

src/refs.c

@@ -287,6 +287,15 @@ static int loose_write(git_reference *ref)
 	if (git_buf_joinpath(&ref_path, ref->owner->path_repository, ref->name) < 0)
 		return -1;
 
+	/* Remove a possibly existing empty directory hierarchy 
+	 * which name would collide with the reference name
+	 */
+	if (git_path_isdir(git_buf_cstr(&ref_path)) && 
+		(git_futils_rmdir_r(git_buf_cstr(&ref_path), GIT_DIRREMOVAL_ONLY_EMPTY_DIRS) < 0)) {
+			git_buf_free(&ref_path);
+			return -1;
+		}
+
 	if (git_filebuf_open(&file, ref_path.ptr, GIT_FILEBUF_FORCE) < 0) {
 		git_buf_free(&ref_path);
 		return -1;

tests-clar/refs/branches/move.c

+#include "clar_libgit2.h"
+#include "branch.h"
+
+static git_repository *repo;
+
+void test_refs_branches_move__initialize(void)
+{
+	cl_fixture_sandbox("testrepo.git");
+	cl_git_pass(git_repository_open(&repo, "testrepo.git"));
+}
+
+void test_refs_branches_move__cleanup(void)
+{
+	git_repository_free(repo);
+
+	cl_fixture_cleanup("testrepo.git");
+}
+
+#define NEW_BRANCH_NAME "new-branch-on-the-block"
+
+void test_refs_branches_move__can_move_a_local_branch(void)
+{
+	cl_git_pass(git_branch_move(repo, "br2", NEW_BRANCH_NAME, 0));
+}
+
+void test_refs_branches_move__can_move_a_local_branch_to_a_different_namespace(void)
+{
+	/* Downward */
+	cl_git_pass(git_branch_move(repo, "br2", "somewhere/" NEW_BRANCH_NAME, 0));
+
+	/* Upward */
+	cl_git_pass(git_branch_move(repo, "somewhere/" NEW_BRANCH_NAME, "br2", 0));
+}
+
+void test_refs_branches_move__can_move_a_local_branch_to_a_partially_colliding_namespace(void)
+{
+	/* Downward */
+	cl_git_pass(git_branch_move(repo, "br2", "br2/" NEW_BRANCH_NAME, 0));
+
+	/* Upward */
+	cl_git_pass(git_branch_move(repo, "br2/" NEW_BRANCH_NAME, "br2", 0));
+}
+
+void test_refs_branches_move__can_not_move_a_branch_if_its_destination_name_collide_with_an_existing_one(void)
+{
+	cl_git_fail(git_branch_move(repo, "br2", "master", 0));
+}
+
+void test_refs_branches_move__can_not_move_a_non_existing_branch(void)
+{
+	cl_git_fail(git_branch_move(repo, "i-am-no-branch", NEW_BRANCH_NAME, 0));
+}
+
+void test_refs_branches_move__can_force_move_over_an_existing_branch(void)
+{
+	cl_git_pass(git_branch_move(repo, "br2", "master", 1));
+}
+
+void test_refs_branches_move__can_not_move_a_branch_through_its_canonical_name(void)
+{
+	cl_git_fail(git_branch_move(repo, "refs/heads/br2", NEW_BRANCH_NAME, 1));
+}