From f4997c04877aba00691cee586687988d3e348a2d Mon Sep 17 00:00:00 2001
From: Amaury Chamayou <amchamay@microsoft.com>
Date: Fri, 15 Dec 2023 10:58:09 +0000
Subject: [PATCH] Fix path serialised_size calculation

---
 merklecpp.h    | 9 ++++++++-
 test/paths.cpp | 4 ++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/merklecpp.h b/merklecpp.h
index 2cd0aea..ed5a975 100644
--- a/merklecpp.h
+++ b/merklecpp.h
@@ -424,7 +424,14 @@ namespace merkle
     /// @brief The size of the serialised path in number of bytes
     size_t serialised_size() const
     {
-      return sizeof(_leaf) + elements.size() * sizeof(Element);
+      return sizeof(_leaf) +
+      sizeof(uint64_t) + // leaf index
+      sizeof(uint64_t) + // max index
+      sizeof(uint64_t) + // number of elements
+      elements.size() * (
+        sizeof(Element::hash) + // hash
+        sizeof(uint8_t) // direction
+      );
     }
 
     /// @brief Index of the leaf of the path
diff --git a/test/paths.cpp b/test/paths.cpp
index 3b80401..03ddb79 100644
--- a/test/paths.cpp
+++ b/test/paths.cpp
@@ -56,6 +56,10 @@ int main()
         auto path = mt.path(i);
         if (!path->verify(root))
           throw std::runtime_error("path verification failed");
+        std::vector<uint8_t> serialised_path;
+        path->serialise(serialised_path);
+        if (path->serialised_size() != serialised_path.size())
+          throw std::runtime_error("serialised_size() != serialised_path.size()");
       }
     }