fix(router): harden policy store file handling

Author: eddierichter-amd

src/cpp/include/lemon/routing_policy_store.h

@@ -43,6 +43,8 @@ class RoutingPolicyStore {
     ClassifierServices services_;
     RoutingPolicyParseOptions parse_options_;
     std::unique_ptr<DirectoryWatcher> watcher_;
+    // TODO(C++20): replace std::atomic_load/store free functions with a
+    // std::atomic<std::shared_ptr<const Snapshot>> member (deprecated in C++20).
     std::shared_ptr<const Snapshot> snapshot_;
 };
 

src/cpp/server/routing_policy_store.cpp

@@ -3,7 +3,9 @@
 #include "lemon/model_types.h"
 #include "lemon/utils/aixlog.hpp"
 
+#include <algorithm>
 #include <atomic>
+#include <cctype>
 #include <filesystem>
 #include <fstream>
 #include <set>
@@ -16,7 +18,10 @@ namespace fs = std::filesystem;
 namespace {
 
 bool is_json_file(const fs::path& path) {
-    return path.has_extension() && path.extension() == ".json";
+    std::string extension = path.extension().string();
+    std::transform(extension.begin(), extension.end(), extension.begin(),
+                   [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
+    return extension == ".json";
 }
 
 json load_json_file(const fs::path& path) {

test/cpp/test_routing_policy_store.cpp

@@ -141,6 +141,22 @@ static void test_invalid_policy_reports_error() {
     fs::remove_all(dir);
 }
 
+static void test_uppercase_json_extension_loads_policy() {
+    fs::path dir = make_temp_dir();
+    fs::path policy_path = dir / "router.JSON";
+    json doc = load_fixture("l1_keywords.json");
+    write_json(policy_path, doc);
+
+    lemon::testing::FakeClassifierServices fake;
+    RoutingPolicyStore store(dir.string(), fake.make());
+    auto snapshot = store.reload();
+
+    check("uppercase .JSON policy file extension is accepted",
+          snapshot->engines.count("user.Router-Keywords") == 1);
+
+    fs::remove_all(dir);
+}
+
 static void test_duplicate_policy_model_names_report_errors() {
     fs::path dir = make_temp_dir();
     json doc = load_fixture("l1_keywords.json");
@@ -165,6 +181,7 @@ int main() {
     test_reload_swaps_snapshot();
     test_directory_watcher_reload();
     test_invalid_policy_reports_error();
+    test_uppercase_json_extension_loads_policy();
     test_duplicate_policy_model_names_report_errors();
 
     if (g_failures == 0) {