added mutex

src/users/change_user.cpp

@@ -46,11 +46,13 @@ void change_user(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "access reject in change user request");
         return;
     }
-
-    std::ifstream usersfile(USERS_FILE);
-    nlohmann::json all_users = nlohmann::json::parse(usersfile);
-    usersfile.close();
-
+    nlohmann::json all_users;
+    {
+        std::lock_guard<std::mutex> lock(usersfilemutex);
+        std::ifstream usersfile(USERS_FILE);
+        all_users = nlohmann::json::parse(usersfile);
+        usersfile.close();
+    }
     std::string changeusruserid = userid;
     if (json_body["userid"] != nullptr) {
         changeusruserid = json_body["userid"];
@@ -103,6 +105,7 @@ void change_user(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "can't find this user in change user request");
         return;
     }
+    std::lock_guard<std::mutex> lock(usersfilemutex);
     std::ofstream usersfilew(USERS_FILE);
     usersfilew << all_users.dump(4);
     usersfilew.close();