[PATCH v2 1/2] dir: encapsulate excludes_file lazy-load

[Tian Yuchen <cat@malon.dev>]

The global variable 'excludes_file' is used to track the path to the
global ignore file, 'core.excludesfile'. If this variable is NULL,
setup_standard_excludes() in dir.c forcefully evaluates and assigns
the XDG default path to it.

Introduce repo_excludes_file() as a getter to encapsulate this
lazy-loading logic. This prepares the variable to be safely moved
into 'struct repo_config_values' in the subsequent commit.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Ayush Chandekar <ayu.chandekar@gmail.com>
Mentored-by: Olamide Caleb Bello <belkid98@gmail.com>
Signed-off-by: Tian Yuchen <cat@malon.dev>
---
 dir.c         | 4 ++--
 environment.c | 7 +++++++
 environment.h | 5 +++++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/dir.c b/dir.c
index 7a73690fbc..4f87a52b3c 100644
--- a/dir.c
+++ b/dir.c
@@ -3481,11 +3481,11 @@ static GIT_PATH_FUNC(git_path_info_exclude, "info/exclude")
 
 void setup_standard_excludes(struct dir_struct *dir)
 {
+	const char *excludes_file = repo_excludes_file(the_repository);
+
 	dir->exclude_per_dir = ".gitignore";
 
 	/* core.excludesfile defaulting to $XDG_CONFIG_HOME/git/ignore */
-	if (!excludes_file)
-		excludes_file = xdg_config_home("ignore");
 	if (excludes_file && !access_or_warn(excludes_file, R_OK, 0))
 		add_patterns_from_file_1(dir, excludes_file,
 					 dir->untracked ? &dir->internal.ss_excludes_file : NULL);
diff --git a/environment.c b/environment.c
index ba2c60103f..8efcaeafa6 100644
--- a/environment.c
+++ b/environment.c
@@ -134,6 +134,13 @@ int is_bare_repository(void)
 	return is_bare_repository_cfg && !repo_get_work_tree(the_repository);
 }
 
+const char *repo_excludes_file(struct repository *repo)
+{
+	if (!excludes_file)
+		excludes_file = xdg_config_home("ignore");
+	return excludes_file;
+}
+
 int have_git_dir(void)
 {
 	return startup_info->have_repository
diff --git a/environment.h b/environment.h
index 6f18286955..52d531e4ea 100644
--- a/environment.h
+++ b/environment.h
@@ -133,6 +133,11 @@ int git_default_config(const char *, const char *,
 int git_default_core_config(const char *var, const char *value,
 			    const struct config_context *ctx, void *cb);
 
+/*
+ * TODO: This still relies on the global state.
+ */
+const char *repo_excludes_file(struct repository *repo);
+
 void repo_config_values_init(struct repo_config_values *cfg);
 
 /*
-- 
2.43.0