From be3c62209592511b67e5b78d743102d6315ded8e Mon Sep 17 00:00:00 2001
From: Lee Bousfield <ljbousfield@gmail.com>
Date: Thu, 12 Dec 2024 10:10:28 -0700
Subject: [PATCH] Also avoid allocating zero len slice in ProveNextStep

---
 validator/server_arb/machine.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/validator/server_arb/machine.go b/validator/server_arb/machine.go
index c781234124..e4e07d3c2d 100644
--- a/validator/server_arb/machine.go
+++ b/validator/server_arb/machine.go
@@ -306,8 +306,11 @@ func (m *ArbitratorMachine) ProveNextStep() []byte {
 
 	output := &C.RustBytes{}
 	C.arbitrator_gen_proof(m.ptr, output)
+	defer C.free_rust_bytes(*output)
+	if output.len == 0 {
+		return nil
+	}
 	proofBytes := C.GoBytes(unsafe.Pointer(output.ptr), C.int(output.len))
-	C.free_rust_bytes(*output)
 
 	return proofBytes
 }