lock_ref_for_update(): don't re-read non-symbolic references

diff --git a/refs/files-backend.c b/refs/files-backend.c
index ffc30fd23213078718aa187bfff9ca29ab312acd..7bc18322aaae00aada50a2842de09ed4e8efecc0 100644 (file)
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -3436,33 +3436,45 @@ static int lock_ref_for_update(struct ref_update *update,
 
        lock = update->lock;
 
-       if (read_ref_full(update->refname,
-                         mustexist ? RESOLVE_REF_READING : 0,
-                         lock->old_oid.hash, NULL)) {
-               if (update->flags & REF_HAVE_OLD) {
-                       strbuf_addf(err, "cannot lock ref '%s': can't resolve old value",
-                                   update->refname);
+       if (update->type & REF_ISSYMREF) {
+               if (read_ref_full(update->refname,
+                                 mustexist ? RESOLVE_REF_READING : 0,
+                                 lock->old_oid.hash, NULL)) {
+                       if (update->flags & REF_HAVE_OLD) {
+                               strbuf_addf(err, "cannot lock ref '%s': can't resolve old value",
+                                           update->refname);
+                               return TRANSACTION_GENERIC_ERROR;
+                       } else {
+                               hashclr(lock->old_oid.hash);
+                       }
+               }
+               if ((update->flags & REF_HAVE_OLD) &&
+                   hashcmp(lock->old_oid.hash, update->old_sha1)) {
+                       strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s",
+                                   update->refname,
+                                   sha1_to_hex(lock->old_oid.hash),
+                                   sha1_to_hex(update->old_sha1));
                        return TRANSACTION_GENERIC_ERROR;
-               } else {
-                       hashclr(lock->old_oid.hash);
                }
-       }
-       if ((update->flags & REF_HAVE_OLD) &&
-           hashcmp(lock->old_oid.hash, update->old_sha1)) {
-               strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s",
-                           update->refname,
-                           sha1_to_hex(lock->old_oid.hash),
-                           sha1_to_hex(update->old_sha1));
-               return TRANSACTION_GENERIC_ERROR;
-       }
 
-       if (update->type & REF_ISSYMREF) {
                if (!(update->flags & REF_NODEREF)) {
                        ret = split_symref_update(update, referent.buf, transaction,
                                                  affected_refnames, err);
                        if (ret)
                                return ret;
                }
+       } else if ((update->flags & REF_HAVE_OLD) &&
+                  hashcmp(lock->old_oid.hash, update->old_sha1)) {
+               if (is_null_sha1(update->old_sha1))
+                       strbuf_addf(err, "cannot lock ref '%s': reference already exists",
+                                   update->refname);
+               else
+                       strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s",
+                                   update->refname,
+                                   sha1_to_hex(lock->old_oid.hash),
+                                   sha1_to_hex(update->old_sha1));
+
+               return TRANSACTION_GENERIC_ERROR;
        }
 
        if ((update->flags & REF_HAVE_NEW) &&