worktree: introduce git_worktree_add options

The `git_worktree_add` function currently accepts only a path and name
for the new work tree. As we may want to expand these parameters in
future versions without adding additional parameters to the function for
every option, this commit introduces our typical pattern of an options
struct. Right now, this structure is still empty, which will change with
the next commit.

include/git2/worktree.h

@@ -74,6 +74,25 @@ GIT_EXTERN(void) git_worktree_free(git_worktree *wt);
  */
 GIT_EXTERN(int) git_worktree_validate(const git_worktree *wt);
 
+typedef struct git_worktree_add_options {
+	unsigned int version;
+} git_worktree_add_options;
+
+#define GIT_WORKTREE_ADD_OPTIONS_VERSION 1
+#define GIT_WORKTREE_ADD_OPTIONS_INIT {GIT_WORKTREE_ADD_OPTIONS_VERSION}
+
+/**
+ * Initializes a `git_worktree_add_options` with default vaules.
+ * Equivalent to creating an instance with
+ * GIT_WORKTREE_ADD_OPTIONS_INIT.
+ *
+ * @param opts the struct to initialize
+ * @param version Verison of struct; pass `GIT_WORKTREE_ADD_OPTIONS_VERSION`
+ * @return Zero on success; -1 on failure.
+ */
+int git_worktree_add_init_options(git_worktree_add_options *opts,
+	unsigned int version);
+
 /**
  * Add a new working tree
  *
@@ -85,9 +104,12 @@ GIT_EXTERN(int) git_worktree_validate(const git_worktree *wt);
  * @param repo Repository to create working tree for
  * @param name Name of the working tree
  * @param path Path to create working tree at
+ * @param opts Options to modify default behavior. May be NULL
  * @return 0 or an error code
  */
-GIT_EXTERN(int) git_worktree_add(git_worktree **out, git_repository *repo, const char *name, const char *path);
+GIT_EXTERN(int) git_worktree_add(git_worktree **out, git_repository *repo,
+	const char *name, const char *path,
+	const git_worktree_add_options *opts);
 
 /**
  * Lock worktree if not already locked

src/worktree.c

@@ -269,15 +269,32 @@ out:
 	return err;
 }
 
-int git_worktree_add(git_worktree **out, git_repository *repo, const char *name, const char *worktree)
+int git_worktree_add_init_options(git_worktree_add_options *opts,
+	unsigned int version)
+{
+	GIT_INIT_STRUCTURE_FROM_TEMPLATE(opts, version,
+		git_worktree_add_options, GIT_WORKTREE_ADD_OPTIONS_INIT);
+	return 0;
+}
+
+int git_worktree_add(git_worktree **out, git_repository *repo,
+	const char *name, const char *worktree,
+	const git_worktree_add_options *opts)
 {
 	git_buf gitdir = GIT_BUF_INIT, wddir = GIT_BUF_INIT, buf = GIT_BUF_INIT;
 	git_reference *ref = NULL, *head = NULL;
 	git_commit *commit = NULL;
 	git_repository *wt = NULL;
 	git_checkout_options coopts = GIT_CHECKOUT_OPTIONS_INIT;
+	git_worktree_add_options wtopts = GIT_WORKTREE_ADD_OPTIONS_INIT;
 	int err;
 
+	GITERR_CHECK_VERSION(
+		opts, GIT_WORKTREE_ADD_OPTIONS_VERSION, "git_worktree_add_options");
+
+	if (opts)
+		memcpy(&wtopts, opts, sizeof(wtopts));
+
 	assert(out && repo && name && worktree);
 
 	*out = NULL;

tests/worktree/submodule.c

@@ -74,7 +74,7 @@ void test_worktree_submodule__resolve_relative_url(void)
 	cl_git_pass(git_repository_open(&child.repo, WORKTREE_CHILD));
 
 	/* Create worktree of submodule repository */
-	cl_git_pass(git_worktree_add(&wt, child.repo, "subdir", wt_path.ptr));
+	cl_git_pass(git_worktree_add(&wt, child.repo, "subdir", wt_path.ptr, NULL));
 	cl_git_pass(git_repository_open_from_worktree(&repo, wt));
 
 	cl_git_pass(git_submodule_resolve_url(&sm_relative_path, repo,

tests/worktree/worktree.c

@@ -215,7 +215,7 @@ void test_worktree_worktree__init(void)
 	git_buf path = GIT_BUF_INIT;
 
 	cl_git_pass(git_buf_joinpath(&path, fixture.repo->workdir, "../worktree-new"));
-	cl_git_pass(git_worktree_add(&wt, fixture.repo, "worktree-new", path.ptr));
+	cl_git_pass(git_worktree_add(&wt, fixture.repo, "worktree-new", path.ptr, NULL));
 
 	/* Open and verify created repo */
 	cl_git_pass(git_repository_open(&repo, path.ptr));
@@ -240,7 +240,7 @@ void test_worktree_worktree__init_existing_branch(void)
 	cl_git_pass(git_branch_create(&branch, fixture.repo, "worktree-new", commit, false));
 
 	cl_git_pass(git_buf_joinpath(&path, fixture.repo->workdir, "../worktree-new"));
-	cl_git_fail(git_worktree_add(&wt, fixture.repo, "worktree-new", path.ptr));
+	cl_git_fail(git_worktree_add(&wt, fixture.repo, "worktree-new", path.ptr, NULL));
 
 	git_buf_free(&path);
 	git_commit_free(commit);
@@ -254,7 +254,7 @@ void test_worktree_worktree__init_existing_worktree(void)
 	git_buf path = GIT_BUF_INIT;
 
 	cl_git_pass(git_buf_joinpath(&path, fixture.repo->workdir, "../worktree-new"));
-	cl_git_fail(git_worktree_add(&wt, fixture.repo, "testrepo-worktree", path.ptr));
+	cl_git_fail(git_worktree_add(&wt, fixture.repo, "testrepo-worktree", path.ptr, NULL));
 
 	cl_git_pass(git_worktree_lookup(&wt, fixture.repo, "testrepo-worktree"));
 	cl_assert_equal_s(wt->gitlink_path, fixture.worktree->gitlink);
@@ -279,7 +279,7 @@ void test_worktree_worktree__init_existing_path(void)
 	}
 
 	cl_git_pass(git_buf_joinpath(&path, fixture.repo->workdir, "../testrepo-worktree"));
-	cl_git_fail(git_worktree_add(&wt, fixture.repo, "worktree-new", path.ptr));
+	cl_git_fail(git_worktree_add(&wt, fixture.repo, "worktree-new", path.ptr, NULL));
 
 	/* Verify files have not been re-created */
 	for (i = 0; i < ARRAY_SIZE(wtfiles); i++) {
@@ -303,7 +303,7 @@ void test_worktree_worktree__init_submodule(void)
 	cl_git_pass(git_buf_joinpath(&path, repo->workdir, "sm_unchanged"));
 	cl_git_pass(git_repository_open(&sm, path.ptr));
 	cl_git_pass(git_buf_joinpath(&path, repo->workdir, "../worktree/"));
-	cl_git_pass(git_worktree_add(&worktree, sm, "repo-worktree", path.ptr));
+	cl_git_pass(git_worktree_add(&worktree, sm, "repo-worktree", path.ptr, NULL));
 	cl_git_pass(git_repository_open_from_worktree(&wt, worktree));
 
 	cl_git_pass(git_path_prettify_dir(&path, path.ptr, NULL));