From 4c3b8bf73c3228e38687ec7be6702f57f3c3a401 Mon Sep 17 00:00:00 2001
From: Nicklas Boman <smurfd@gmail.com>
Date: Mon, 15 Jul 2024 21:34:15 +0200
Subject: [PATCH] c backend found u64 overflow bug

---
 lotordb/src/keys.c        | 2 ++
 lotordb/src/tests/tests.c | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/lotordb/src/keys.c b/lotordb/src/keys.c
index 336a956..1da984f 100644
--- a/lotordb/src/keys.c
+++ b/lotordb/src/keys.c
@@ -113,6 +113,8 @@ static u64 sub(u64 *a, const u64 *b, const u64 *c) {
 
 //
 // Multiply
+// BUG: Both b[j] and c[k - j] is 18446744073709551615 == u64max
+//      which is triggered once the run fails. See test howto trigger it repeadedly
 static void mul(u64 *a, const u64 *b, const u64 *c) {
   u64 r2 = 0, di22 = DIGITS * 2 - 1;
   unsigned __int128 r = 0;
diff --git a/lotordb/src/tests/tests.c b/lotordb/src/tests/tests.c
index 12150cf..f13e911 100644
--- a/lotordb/src/tests/tests.c
+++ b/lotordb/src/tests/tests.c
@@ -99,6 +99,11 @@ void test_keys_verify(void) {
   uint8_t sig[BYTES * 2],  pubkey[BYTES + 1],  sec[BYTES], privkey[BYTES], h[BYTES] = {0};
   u64 k[BYTES] = {0};
   u64rnd_array(h, k, BYTES);
+  // BUG: uncomment to trigger u64 overflow bug
+  //for (int i = 0; i < BYTES;++i) {
+  //  h[i] = 66;
+  //  k[i] = 99999999;
+  //}
   assert(keys_make(pubkey, privkey, k));
   assert(keys_secr(pubkey, privkey, sec, k));
   assert(keys_sign(privkey, h, sig, k));