From 022046107186746913ef43a33f4b6862817bf6da Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Thu, 9 Apr 2020 23:04:11 -0400
Subject: repository: mark the "refs" pointer as private

The "refs" pointer in a struct repository starts life as NULL, but then
is lazily initialized when it is accessed via get_main_ref_store().
However, it's easy for calling code to forget this and access it
directly, leading to code which works _some_ of the time, but fails if
it is called before anybody else accesses the refs.

This was the cause of the bug fixed by 5ff4b920eb (sha1-name: do not
assume that the ref store is initialized, 2020-04-09). In order to
prevent similar bugs, let's more clearly mark the "refs" field as
private.

In addition to helping future code, the name change will help us audit
any existing direct uses. Besides get_main_ref_store() itself, it turns
out there is only one. But we know it's OK as it is on the line directly
after the fix from 5ff4b920eb, which will have initialized the pointer.
However it's still a good idea for it to model the proper use of the
accessing function, so we'll convert it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs.c b/refs.c
index 92d1f6d..4cc32e7 100644
--- a/refs.c
+++ b/refs.c
@@ -1774,14 +1774,14 @@ static struct ref_store *ref_store_init(const char *gitdir,
 
 struct ref_store *get_main_ref_store(struct repository *r)
 {
-	if (r->refs)
-		return r->refs;
+	if (r->refs_private)
+		return r->refs_private;
 
 	if (!r->gitdir)
 		BUG("attempting to get main_ref_store outside of repository");
 
-	r->refs = ref_store_init(r->gitdir, REF_STORE_ALL_CAPS);
-	return r->refs;
+	r->refs_private = ref_store_init(r->gitdir, REF_STORE_ALL_CAPS);
+	return r->refs_private;
 }
 
 /*
diff --git a/repository.h b/repository.h
index 4fb6a58..4ecc201 100644
--- a/repository.h
+++ b/repository.h
@@ -39,8 +39,12 @@ struct repository {
 	 */
 	struct parsed_object_pool *parsed_objects;
 
-	/* The store in which the refs are held. */
-	struct ref_store *refs;
+	/*
+	 * The store in which the refs are held. This should generally only be
+	 * accessed via get_main_ref_store(), as that will lazily initialize
+	 * the ref object.
+	 */
+	struct ref_store *refs_private;
 
 	/*
 	 * Contains path to often used file names.
diff --git a/sha1-name.c b/sha1-name.c
index 3aba629..c679e24 100644
--- a/sha1-name.c
+++ b/sha1-name.c
@@ -1772,7 +1772,7 @@ static enum get_oid_result get_oid_with_context_1(struct repository *repo,
 			cb.repo = repo;
 			cb.list = &list;
 			refs_for_each_ref(get_main_ref_store(repo), handle_one_ref, &cb);
-			refs_head_ref(repo->refs, handle_one_ref, &cb);
+			refs_head_ref(get_main_ref_store(repo), handle_one_ref, &cb);
 			commit_list_sort_by_date(&list);
 			return get_oid_oneline(repo, name + 2, oid, list);
 		}
-- 
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