config-check command in osqueryd

This addresses #585

include/osquery/config.h

@@ -127,6 +127,15 @@ class Config {
    */
   Status getMD5(std::string& hashString);
 
+  /**
+   * @brief Check to ensure that the config is accessible and properly
+   * formatted
+   *
+   * @return an instance of osquery::Status, indicating the success or failure
+   * of the operation.
+   */
+  static osquery::Status checkConfig();
+
  private:
   /**
    * @brief Default constructor.
@@ -173,7 +182,6 @@ class Config {
    * @return an instance of osquery::Status, indicating the success or failure
    * of the operation.
    */
-
   static osquery::Status genConfig(std::string& conf);
 
  private:

osquery/config/config.cpp

@@ -138,4 +138,9 @@ Status Config::getMD5(std::string& hash_string) {
 
   return Status(0, "OK");
 }
+
+Status Config::checkConfig() {
+  OsqueryConfig c;
+  return genConfig(c);
+}
 }

osquery/main/daemon.cpp

@@ -26,9 +26,24 @@ DEFINE_osquery_flag(bool, daemonize, false, "Run as daemon (osqueryd only).");
 }
 #endif
 
+namespace osquery {
+DEFINE_osquery_flag(bool,
+                    config_check,
+                    false,
+                    "Check the format and accessibility of the daemon");
+}
+
 int main(int argc, char* argv[]) {
   osquery::initOsquery(argc, argv, osquery::OSQUERY_TOOL_DAEMON);
 
+  if (osquery::FLAGS_config_check) {
+    auto s = osquery::Config::checkConfig();
+    if (!s.ok()) {
+      std::cerr << "Error reading config: " << s.toString() << "\n";
+    }
+    return s.getCode();
+  }
+
 #ifndef __APPLE__
   // OSX uses launchd to daemonize.
   if (osquery::FLAGS_daemonize) {