[PATCH v3 12/19] initial_ref_transaction_commit(): check for duplicate refs

[Michael Haggerty <mhagger@alum.mit.edu>]

Error out if the ref_transaction includes more than one update for any
refname.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 refs.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/refs.c b/refs.c
index 31661c7..53d9e45 100644
--- a/refs.c
+++ b/refs.c
@@ -4087,12 +4087,22 @@ int initial_ref_transaction_commit(struct ref_transaction *transaction,
 	int ret = 0, i;
 	int n = transaction->nr;
 	struct ref_update **updates = transaction->updates;
+	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
 
 	assert(err);
 
 	if (transaction->state != REF_TRANSACTION_OPEN)
 		die("BUG: commit called for transaction that is not open");
 
+	/* Fail if a refname appears more than once in the transaction: */
+	for (i = 0; i < n; i++)
+		string_list_append(&affected_refnames, updates[i]->refname);
+	string_list_sort(&affected_refnames);
+	if (ref_update_reject_duplicates(&affected_refnames, err)) {
+		ret = TRANSACTION_GENERIC_ERROR;
+		goto cleanup;
+	}
+
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
 
@@ -4125,6 +4135,7 @@ int initial_ref_transaction_commit(struct ref_transaction *transaction,
 
 cleanup:
 	transaction->state = REF_TRANSACTION_CLOSED;
+	string_list_clear(&affected_refnames, 0);
 	return ret;
 }
 
-- 
2.1.4