Merge branch 'bf/set-head-symref'

When "git fetch $remote" notices that refs/remotes/$remote/HEAD is
missing and discovers what branch the other side points with its
HEAD, refs/remotes/$remote/HEAD is updated to point to it.

* bf/set-head-symref:
  fetch set_head: handle mirrored bare repositories
  fetch: set remote/HEAD if it does not exist
  refs: add create_only option to refs_update_symref_extended
  refs: add TRANSACTION_CREATE_EXISTS error
  remote set-head: better output for --auto
  remote set-head: refactor for readability
  refs: atomically record overwritten ref in update_symref
  refs: standardize output of refs_read_symbolic_ref
  t/t5505-remote: test failure of set-head
  t/t5505-remote: set default branch to main

1 files changed, 19 insertions, 12 deletions

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 64f51f0da9..4e3545de49 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -598,10 +598,9 @@ static int files_read_symbolic_ref(struct ref_store *ref_store, const char *refn
 	unsigned int type;
 
 	ret = read_ref_internal(ref_store, refname, &oid, referent, &type, &failure_errno, 1);
-	if (ret)
-		return ret;
-
-	return !(type & REF_ISSYMREF);
+	if (!ret && !(type & REF_ISSYMREF))
+		return NOT_A_SYMREF;
+	return ret;
 }
 
 int parse_loose_ref_contents(const struct git_hash_algo *algop,
@@ -2509,14 +2508,18 @@ static int split_symref_update(struct ref_update *update,
 static int check_old_oid(struct ref_update *update, struct object_id *oid,
 			 struct strbuf *err)
 {
+	int ret = TRANSACTION_GENERIC_ERROR;
+
 	if (!(update->flags & REF_HAVE_OLD) ||
 		   oideq(oid, &update->old_oid))
 		return 0;
 
-	if (is_null_oid(&update->old_oid))
+	if (is_null_oid(&update->old_oid)) {
 		strbuf_addf(err, "cannot lock ref '%s': "
 			    "reference already exists",
 			    ref_update_original_update_refname(update));
+		ret = TRANSACTION_CREATE_EXISTS;
+	}
 	else if (is_null_oid(oid))
 		strbuf_addf(err, "cannot lock ref '%s': "
 			    "reference is missing but expected %s",
@@ -2529,7 +2532,7 @@ static int check_old_oid(struct ref_update *update, struct object_id *oid,
 			    oid_to_hex(oid),
 			    oid_to_hex(&update->old_oid));
 
-	return -1;
+	return ret;
 }
 
 /*
@@ -2609,9 +2612,11 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 					ret = TRANSACTION_GENERIC_ERROR;
 					goto out;
 				}
-			} else if  (check_old_oid(update, &lock->old_oid, err)) {
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto out;
+			} else {
+				ret = check_old_oid(update, &lock->old_oid, err);
+				if  (ret) {
+					goto out;
+				}
 			}
 		} else {
 			/*
@@ -2642,9 +2647,11 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 				    update->old_target);
 			ret = TRANSACTION_GENERIC_ERROR;
 			goto out;
-		} else if  (check_old_oid(update, &lock->old_oid, err)) {
-			ret = TRANSACTION_GENERIC_ERROR;
-			goto out;
+		} else {
+			ret = check_old_oid(update, &lock->old_oid, err);
+			if  (ret) {
+				goto out;
+			}
 		}
 
 		/*