From 92b9bdd989e5781bc425818857548da590fe9fbd Mon Sep 17 00:00:00 2001
From: "hinto.janai" <hinto.janai@protonmail.com>
Date: Wed, 11 Dec 2024 13:42:45 -0500
Subject: [PATCH] oddities

---
 books/architecture/src/SUMMARY.md             |  3 ++
 .../src/oddities/epee-empty-containers.md     | 35 +++++++++++++++++++
 .../src/oddities/invalid-blocks.md            | 21 +++++++++++
 books/architecture/src/oddities/varint.md     | 19 ++++++++++
 4 files changed, 78 insertions(+)
 create mode 100644 books/architecture/src/oddities/epee-empty-containers.md
 create mode 100644 books/architecture/src/oddities/invalid-blocks.md
 create mode 100644 books/architecture/src/oddities/varint.md

diff --git a/books/architecture/src/SUMMARY.md b/books/architecture/src/SUMMARY.md
index a99d099f..a780b2c2 100644
--- a/books/architecture/src/SUMMARY.md
+++ b/books/architecture/src/SUMMARY.md
@@ -165,7 +165,10 @@
 ---
 
 - [🟢 Monero oddities](oddities/intro.md)
+    - [🟡 Epee empty containers](oddities/epee-empty-containers.md)
+    - [🟡 Invalid blocks](oddities/invalid-blocks.md)
     - [🟡 Little-endian IPv4 addresses](oddities/le-ipv4.md)
+    - [🟡 2 variable integer formats](oddities/varint.md)
 
 ---
 
diff --git a/books/architecture/src/oddities/epee-empty-containers.md b/books/architecture/src/oddities/epee-empty-containers.md
new file mode 100644
index 00000000..6ffd6924
--- /dev/null
+++ b/books/architecture/src/oddities/epee-empty-containers.md
@@ -0,0 +1,35 @@
+# Epee empty containers
+
+## What
+Monero's serialization in the `epee` library, responsible for both JSON and binary encoding, will not serialize containers that are empty.
+
+This causes some issues for the binary format:
+- <https://github.com/monero-rs/monero-epee-bin-serde/issues/49>
+- <https://github.com/monero-project/monero/pull/8940>
+
+For JSON, fields with empty containers will cause the field itself to not be present in the JSON output.
+
+## Expected
+Serialization of the key and an empty field, for example, this is expected:
+```json
+{
+  "empty": [],
+  "non_empty": [1]
+}
+```
+
+However `monerod` will write:
+```json
+{
+  "non_empty": [1]
+}
+```
+
+## Why
+TODO
+
+## Affects
+TODO
+
+## Source
+- TODO
\ No newline at end of file
diff --git a/books/architecture/src/oddities/invalid-blocks.md b/books/architecture/src/oddities/invalid-blocks.md
new file mode 100644
index 00000000..401fc570
--- /dev/null
+++ b/books/architecture/src/oddities/invalid-blocks.md
@@ -0,0 +1,21 @@
+# Invalid blocks
+
+## What
+TODO
+
+- Block 202612
+- Block 685498
+
+## Expected
+TODO
+
+## Why
+TODO
+
+## Affects
+TODO
+
+## Source
+- <https://github.com/monero-project/monero/pull/121>
+- <https://github.com/monero-project/monero/blob/893916ad091a92e765ce3241b94e706ad012b62a/src/crypto/tree-hash.c#L63-L74>
+- <https://github.com/monero-project/monero/blob/893916ad091a92e765ce3241b94e706ad012b62a/src/blockchain_db/blockchain_db.cpp#L450-L456>
\ No newline at end of file
diff --git a/books/architecture/src/oddities/varint.md b/books/architecture/src/oddities/varint.md
new file mode 100644
index 00000000..239b3701
--- /dev/null
+++ b/books/architecture/src/oddities/varint.md
@@ -0,0 +1,19 @@
+# 2 variable integer formats
+
+## What
+Monero has 2 variant integer formats that are used in different contexts.
+
+## Expected
+TODO
+
+## Why
+TODO
+
+- <https://github.com/monero-project/monero/issues/3826>
+- <https://github.com/monero-project/monero/pull/5544>
+
+## Affects
+TODO
+
+## Source
+- TODO