refs: export ref_transaction_update_reflog()

In a subsequent commit we'll add another user that wants to write reflog
entries. This requires them to call `ref_transaction_update_reflog()`,
but that function is local to "refs.c".

Export the function to prepare for the change. While at it, drop the
`flags` field, as all callers are for now expected to use the same flags
anyway.

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

Author: pks-t

refs.c

@@ -1371,27 +1371,21 @@ int ref_transaction_update(struct ref_transaction *transaction,
 	return 0;
 }
 
-/*
- * Similar to`ref_transaction_update`, but this function is only for adding
- * a reflog update. Supports providing custom committer information. The index
- * field can be utiltized to order updates as desired. When not used, the
- * updates default to being ordered by refname.
- */
-static int ref_transaction_update_reflog(struct ref_transaction *transaction,
-					 const char *refname,
-					 const struct object_id *new_oid,
-					 const struct object_id *old_oid,
-					 const char *committer_info,
-					 unsigned int flags,
-					 const char *msg,
-					 uint64_t index,
-					 struct strbuf *err)
+int ref_transaction_update_reflog(struct ref_transaction *transaction,
+				  const char *refname,
+				  const struct object_id *new_oid,
+				  const struct object_id *old_oid,
+				  const char *committer_info,
+				  const char *msg,
+				  uint64_t index,
+				  struct strbuf *err)
 {
 	struct ref_update *update;
+	unsigned int flags;
 
 	assert(err);
 
-	flags |= REF_LOG_ONLY | REF_FORCE_CREATE_REFLOG | REF_NO_DEREF;
+	flags = REF_HAVE_OLD | REF_HAVE_NEW | REF_LOG_ONLY | REF_FORCE_CREATE_REFLOG | REF_NO_DEREF;
 
 	if (!transaction_refname_valid(refname, new_oid, flags, err))
 		return -1;
@@ -3019,8 +3013,7 @@ static int migrate_one_reflog_entry(struct object_id *old_oid,
 
 	ret = ref_transaction_update_reflog(data->transaction, data->refname,
 					    new_oid, old_oid, data->sb->buf,
-					    REF_HAVE_NEW | REF_HAVE_OLD, msg,
-					    data->index++, data->errbuf);
+					    msg, data->index++, data->errbuf);
 	return ret;
 }
 

refs.h

@@ -795,6 +795,21 @@ int ref_transaction_update(struct ref_transaction *transaction,
 			   unsigned int flags, const char *msg,
 			   struct strbuf *err);
 
+/*
+ * Similar to `ref_transaction_update`, but this function is only for adding
+ * a reflog update. Supports providing custom committer information. The index
+ * field can be utiltized to order updates as desired. When set to zero, the
+ * updates default to being ordered by refname.
+ */
+int ref_transaction_update_reflog(struct ref_transaction *transaction,
+				  const char *refname,
+				  const struct object_id *new_oid,
+				  const struct object_id *old_oid,
+				  const char *committer_info,
+				  const char *msg,
+				  uint64_t index,
+				  struct strbuf *err);
+
 /*
  * Add a reference creation to transaction. new_oid is the value that
  * the reference should have after the update; it must not be