fix(config): handle malformed prep_cmd and dd_mode_remapping JSON in config

src/config.cpp

@@ -693,13 +693,19 @@ namespace config {
       std::stringstream json_stream;
       json_stream << "{\"dd_mode_remapping\":" << value << "}";
 
-      boost::property_tree::ptree json_tree;
-      boost::property_tree::read_json(json_stream, json_tree);
-
       video_t::dd_t::mode_remapping_t output;
-      parse_entry_list(json_tree.get_child("dd_mode_remapping.mixed"), output.mixed);
-      parse_entry_list(json_tree.get_child("dd_mode_remapping.resolution_only"), output.resolution_only);
-      parse_entry_list(json_tree.get_child("dd_mode_remapping.refresh_rate_only"), output.refresh_rate_only);
+      try {
+        boost::property_tree::ptree json_tree;
+        boost::property_tree::read_json(json_stream, json_tree);
+
+        parse_entry_list(json_tree.get_child("dd_mode_remapping.mixed"), output.mixed);
+        parse_entry_list(json_tree.get_child("dd_mode_remapping.resolution_only"), output.resolution_only);
+        parse_entry_list(json_tree.get_child("dd_mode_remapping.refresh_rate_only"), output.refresh_rate_only);
+      } catch (const boost::property_tree::ptree_error &err) {
+        // don't let bad json kill startup, skip remapping
+        BOOST_LOG(warning) << "Ignoring invalid dd_mode_remapping configuration: "sv << err.what();
+        return {};
+      }
 
       return output;
     }
@@ -1426,15 +1432,21 @@ namespace config {
     // We need to add a wrapping object to make it valid JSON, otherwise ptree cannot parse it.
     jsonStream << "{\"prep_cmd\":" << string << "}";
 
-    boost::property_tree::ptree jsonTree;
-    boost::property_tree::read_json(jsonStream, jsonTree);
+    try {
+      boost::property_tree::ptree jsonTree;
+      boost::property_tree::read_json(jsonStream, jsonTree);
 
-    for (auto &[_, prep_cmd] : jsonTree.get_child("prep_cmd"s)) {
-      auto do_cmd = prep_cmd.get_optional<std::string>("do"s);
-      auto undo_cmd = prep_cmd.get_optional<std::string>("undo"s);
-      auto elevated = prep_cmd.get_optional<bool>("elevated"s);
+      for (auto &[_, prep_cmd] : jsonTree.get_child("prep_cmd"s)) {
+        auto do_cmd = prep_cmd.get_optional<std::string>("do"s);
+        auto undo_cmd = prep_cmd.get_optional<std::string>("undo"s);
+        auto elevated = prep_cmd.get_optional<bool>("elevated"s);
 
-      input.emplace_back(do_cmd.value_or(""), undo_cmd.value_or(""), elevated.value_or(false));
+        input.emplace_back(do_cmd.value_or(""), undo_cmd.value_or(""), elevated.value_or(false));
+      }
+    } catch (const boost::property_tree::ptree_error &err) {
+      // don't let bad json kill startup, skip this setting
+      BOOST_LOG(warning) << "Ignoring invalid "sv << name << " configuration: "sv << err.what();
+      input.clear();
     }
   }
 

tests/unit/test_config.cpp

@@ -0,0 +1,81 @@
+/**
+ * @file tests/unit/test_config.cpp
+ * @brief Test src/config.* configuration parsing helpers.
+ */
+// test imports
+#include "../tests_common.h"
+
+// standard imports
+#include <string>
+#include <string_view>
+#include <unordered_map>
+#include <vector>
+
+// local imports
+#include <src/config.h>
+
+// internal helpers, not exposed in config.h
+namespace config {
+  void list_prep_cmd_f(std::unordered_map<std::string, std::string> &vars, const std::string &name, std::vector<prep_cmd_t> &input);
+
+  namespace dd {
+    video_t::dd_t::mode_remapping_t mode_remapping_from_view(std::string_view value);
+  }  // namespace dd
+}  // namespace config
+
+struct ConfigParsingTest: BaseTest {};
+
+TEST_F(ConfigParsingTest, PrepCmdMalformedJsonDoesNotThrow) {
+  // bad json here must not kill startup
+  std::unordered_map<std::string, std::string> vars {{"global_prep_cmd", "["}};
+  std::vector<config::prep_cmd_t> input;
+
+  EXPECT_NO_THROW(config::list_prep_cmd_f(vars, "global_prep_cmd", input));
+  EXPECT_TRUE(input.empty());
+}
+
+TEST_F(ConfigParsingTest, PrepCmdValidJsonIsParsed) {
+  std::unordered_map<std::string, std::string> vars {
+    {"global_prep_cmd", R"([{"do":"echo start","undo":"echo stop","elevated":false}])"}
+  };
+  std::vector<config::prep_cmd_t> input;
+
+  ASSERT_NO_THROW(config::list_prep_cmd_f(vars, "global_prep_cmd", input));
+  ASSERT_EQ(input.size(), 1u);
+  EXPECT_EQ(input[0].do_cmd, "echo start");
+  EXPECT_EQ(input[0].undo_cmd, "echo stop");
+  EXPECT_FALSE(input[0].elevated);
+}
+
+TEST_F(ConfigParsingTest, ModeRemappingMalformedJsonReturnsEmpty) {
+  config::video_t::dd_t::mode_remapping_t result;
+  EXPECT_NO_THROW(result = config::dd::mode_remapping_from_view("{ not valid json"));
+  EXPECT_TRUE(result.mixed.empty());
+  EXPECT_TRUE(result.resolution_only.empty());
+  EXPECT_TRUE(result.refresh_rate_only.empty());
+}
+
+TEST_F(ConfigParsingTest, ModeRemappingValidJsonMissingChildKeysReturnsEmpty) {
+  // valid json but missing keys also throws (ptree_bad_path)
+  config::video_t::dd_t::mode_remapping_t result;
+  EXPECT_NO_THROW(result = config::dd::mode_remapping_from_view("[]"));
+  EXPECT_TRUE(result.mixed.empty());
+  EXPECT_TRUE(result.resolution_only.empty());
+  EXPECT_TRUE(result.refresh_rate_only.empty());
+}
+
+TEST_F(ConfigParsingTest, ModeRemappingValidJsonIsParsed) {
+  constexpr std::string_view value = R"({
+    "mixed": [{"requested_resolution":"1920x1080","requested_fps":"60","final_resolution":"2560x1440","final_refresh_rate":"120"}],
+    "resolution_only": [],
+    "refresh_rate_only": []
+  })";
+
+  config::video_t::dd_t::mode_remapping_t result;
+  ASSERT_NO_THROW(result = config::dd::mode_remapping_from_view(value));
+  ASSERT_EQ(result.mixed.size(), 1u);
+  EXPECT_EQ(result.mixed[0].requested_resolution, "1920x1080");
+  EXPECT_EQ(result.mixed[0].requested_fps, "60");
+  EXPECT_EQ(result.mixed[0].final_resolution, "2560x1440");
+  EXPECT_EQ(result.mixed[0].final_refresh_rate, "120");
+}