From 7ea69442b3c877a58340a833ebfd4ac88010c581 Mon Sep 17 00:00:00 2001
From: Brandon Liu <bdon@bdon.org>
Date: Wed, 3 May 2023 12:58:29 +0800
Subject: [PATCH] c++: fix off-by-one error causing out-of-bounds access

---
 cpp/pmtiles.hpp |  2 +-
 cpp/test.cpp    | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/cpp/pmtiles.hpp b/cpp/pmtiles.hpp
index 9fe00c7..bf5e382 100644
--- a/cpp/pmtiles.hpp
+++ b/cpp/pmtiles.hpp
@@ -484,7 +484,7 @@ inline std::tuple<std::string, std::string, int> build_root_leaves(const std::fu
 	std::vector<pmtiles::entryv3> root_entries;
 	std::string leaves_bytes;
 	int num_leaves = 0;
-	for (size_t i = 0; i <= entries.size(); i += leaf_size) {
+	for (size_t i = 0; i < entries.size(); i += leaf_size) {
 		num_leaves++;
 		int end = i + leaf_size;
 		if (i + leaf_size > entries.size()) {
diff --git a/cpp/test.cpp b/cpp/test.cpp
index 37afb5e..3f83237 100644
--- a/cpp/test.cpp
+++ b/cpp/test.cpp
@@ -196,6 +196,16 @@ string mydecompress(const string &input, uint8_t compression) {
 	return input;
 }
 
+MU_TEST(test_build_dirs_one) {
+	vector<entryv3> entries;
+	entries.push_back(entryv3(0, 0, 1, 2));
+	string root_bytes;
+	string leaves_bytes;
+	int num_leaves;
+	tie(root_bytes, leaves_bytes, num_leaves) = build_root_leaves(&mycompress, pmtiles::COMPRESSION_NONE, entries, 1);
+	mu_check(num_leaves == 1);
+}
+
 MU_TEST(test_build_dirs) {
 	vector<entryv3> entries;
 	for (int i = 0; i < 100000; i += 2) {
@@ -259,6 +269,7 @@ MU_TEST_SUITE(test_suite) {
 	MU_RUN_TEST(test_serialize_header);
 	MU_RUN_TEST(test_deserialize_header);
 	MU_RUN_TEST(test_build_dirs);
+	MU_RUN_TEST(test_build_dirs_one);
 }
 
 int main(int argc, char *argv[]) {