refs/files-backend: add longer-scoped copy of string to list

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 0404f2c2333c0fadeb57d225deedc6f0d4afadad..baceef3b3c010138d394da895f4829268a15d0b3 100644 (file)
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2634,13 +2634,12 @@ static int split_symref_update(struct files_ref_store *refs,
 
        /*
         * First make sure that referent is not already in the
-        * transaction. This insertion is O(N) in the transaction
+        * transaction. This check is O(lg N) in the transaction
         * size, but it happens at most once per symref in a
         * transaction.
         */
-       item = string_list_insert(affected_refnames, referent);
-       if (item->util) {
-               /* An entry already existed */
+       if (string_list_has_string(affected_refnames, referent)) {
+               /* An entry already exists */
                strbuf_addf(err,
                            "multiple updates for '%s' (including one "
                            "via symref '%s') are not allowed",
@@ -2675,6 +2674,17 @@ static int split_symref_update(struct files_ref_store *refs,
        update->flags |= REF_LOG_ONLY | REF_NODEREF;
        update->flags &= ~REF_HAVE_OLD;
 
+       /*
+        * Add the referent. This insertion is O(N) in the transaction
+        * size, but it happens at most once per symref in a
+        * transaction. Make sure to add new_update->refname, which will
+        * be valid as long as affected_refnames is in use, and NOT
+        * referent, which might soon be freed by our caller.
+        */
+       item = string_list_insert(affected_refnames, new_update->refname);
+       if (item->util)
+               BUG("%s unexpectedly found in affected_refnames",
+                   new_update->refname);
        item->util = new_update;
 
        return 0;