config: teach repo_config to allow `repo` to be NULL

The `repo` value can be NULL if a builtin command is run outside
any repository. The current implementation of `repo_config()` will
fail if `repo` is NULL.

If the `repo` is NULL the `repo_config()` can ignore the repository
configuration but it should read the other configuration sources like
the system-side configuration instead of failing.

Teach the `repo_config()` to allow `repo` to be NULL by calling the
`read_very_early_config()` which read config but only enumerate system
and global settings.

This will be useful in the following commits.

Suggested-by: Junio C Hamano <gitster@pobox.com>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/config.c b/config.c
index dfd03b9421..f13a2870f1 100644
--- a/config.c
+++ b/config.c
@@ -2521,6 +2521,10 @@ void repo_config_clear(struct repository *repo)
 
 void repo_config(struct repository *repo, config_fn_t fn, void *data)
 {
+	if (!repo) {
+		read_very_early_config(fn, data);
+		return;
+	}
 	git_config_check_init(repo);
 	configset_iter(repo->config, fn, data);
 }