feat: add default config fallback

This reverts commit 6021ec89f5.

README.md

@@ -12,7 +12,7 @@ For info that with "EVIOCGRAB" the keyboard events can be consumed exclusively b
 
 ## Configuration
 
-The configuration can be provided by either specifying a config file path via the `-c` parameter. If no parameter is provided, the default config path under `$HOME/.config/usbMakroBoard.yaml` is used.
+The configuration can be provided by either specifying a config file path via the `-c` parameter. If no parameter is provided, the default config path under `$HOME/.config/UsbMakroBoard.yaml` is used.
 
 Find the config schema in [schemas/config.schema.json](./schemas/config.schema.json) as well as a default config in [config.yaml](./config.yaml).
 

src/main.cpp

@@ -7,6 +7,7 @@
 #include <fcntl.h>
 #include <linux/input.h>
 #include <iostream>
+#include <cstdlib>
 #include <spdlog/spdlog.h>
 #include <spdlog/sinks/stdout_sinks.h>
 #include <yaml-cpp/yaml.h>
@@ -57,7 +58,7 @@ std::pair<int, int> mapKeyEventToRowColumn(int keyEventNumber, const std::unorde
 
 std::string getConfigPathFromCliArguments(int argc, char *argv[])
 {
-    std::string configPath = "";
+    std::string configPath;
     int opt;
     while ((opt = getopt(argc, argv, "c:")) != -1)
     {
@@ -67,14 +68,30 @@ std::string getConfigPathFromCliArguments(int argc, char *argv[])
             configPath = optarg;
             break;
         default:
-            std::cout << "No config path provided. Using default config path: $HOME/.config/usbMakroBoard.yaml\n";
+            std::cerr << "Usage: " << argv[0] << " [-c config_file_path]\n";
-            configPath = "$HOME/.config/usbMakroBoard.yaml";
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    if (configPath.empty()) {
+        const char *home = std::getenv("HOME");
+        if (home != nullptr) {
+            configPath = std::string(home) + "/.config/usbMakroBoard.yaml";
+        }
+        else {
+            std::cerr << "HOME environment variable is not set. Exiting.\n";
+            exit(EXIT_FAILURE);
         }
     }
     
     return configPath;
 }
 
+YAML::Node loadConfig(const std::string &configPath)
+{
+    return YAML::LoadFile(configPath);
+}
+
 int openDevice(const std::string &devicePath)
 {
     int fdKeyboard = open(devicePath.c_str(), O_RDONLY);