ref-filter: properly distinuish pseudo and root refs

The ref-filter interfaces currently define root refs as either a
detached HEAD or a pseudo ref. Pseudo refs aren't root refs though, so
let's properly distinguish those ref types.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/refs.h b/refs.h
index 8489b45265..dc4358727f 100644
--- a/refs.h
+++ b/refs.h
@@ -1080,4 +1080,22 @@ void update_ref_namespace(enum ref_namespace namespace, char *ref);
  */
 int is_root_ref(const char *refname);
 
+/*
+ * Pseudorefs are refs that have different semantics compared to
+ * "normal" refs. These refs can thus not be stored in the ref backend,
+ * but must always be accessed via the filesystem. The following refs
+ * are pseudorefs:
+ *
+ * - FETCH_HEAD may contain multiple object IDs, and each one of them
+ *   carries additional metadata like where it came from.
+ *
+ * - MERGE_HEAD may contain multiple object IDs when merging multiple
+ *   heads.
+ *
+ * Reading, writing or deleting references must consistently go either
+ * through the filesystem (pseudorefs) or through the reference
+ * backend (normal ones).
+ */
+int is_pseudo_ref(const char *refname);
+
 #endif /* REFS_H */