Fix cppcheck warnings

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I18be21d5141630a1da3d5e54740b54a9a06496d9
diff --git a/inc/button_factory.hpp b/inc/button_factory.hpp
index 0d427f7..fc75f4f 100644
--- a/inc/button_factory.hpp
+++ b/inc/button_factory.hpp
@@ -46,7 +46,7 @@
      * @brief this method returns the button interface object
      *    corresponding to the button formfactor name provided
      */
-    std::unique_ptr<ButtonIface> createInstance(std::string name,
+    std::unique_ptr<ButtonIface> createInstance(const std::string& name,
                                                 sdbusplus::bus::bus& bus,
                                                 EventPtr& event,
                                                 buttonConfig& buttonCfg)
diff --git a/inc/button_handler.hpp b/inc/button_handler.hpp
index b3c65f5..baa7400 100644
--- a/inc/button_handler.hpp
+++ b/inc/button_handler.hpp
@@ -39,7 +39,7 @@
      *
      * @param[in] bus - sdbusplus connection object
      */
-    Handler(sdbusplus::bus::bus& bus);
+    explicit Handler(sdbusplus::bus::bus& bus);
 
   private:
     /**
diff --git a/inc/button_interface.hpp b/inc/button_interface.hpp
index 0a0181b..9d85e8e 100644
--- a/inc/button_interface.hpp
+++ b/inc/button_interface.hpp
@@ -108,8 +108,8 @@
         }
     }
 
-    buttonConfig config;
     sdbusplus::bus::bus& bus;
     EventPtr& event;
+    buttonConfig config;
     sd_event_io_handler_t callbackHandler;
 };
diff --git a/inc/common.hpp b/inc/common.hpp
index 82746ee..1b4911f 100644
--- a/inc/common.hpp
+++ b/inc/common.hpp
@@ -24,7 +24,7 @@
 {
     void operator()(sd_event* event) const
     {
-        event = sd_event_unref(event);
+        sd_event_unref(event);
     }
 };
 using EventPtr = std::unique_ptr<sd_event, EventDeleter>;
diff --git a/src/button_handler.cpp b/src/button_handler.cpp
index a819183..764c807 100644
--- a/src/button_handler.cpp
+++ b/src/button_handler.cpp
@@ -277,7 +277,7 @@
     method.append(dbusIfaceName, transitionName, transition);
     bus.call(method);
 }
-void Handler::powerPressed(sdbusplus::message::message& msg)
+void Handler::powerPressed(sdbusplus::message::message& /* msg */)
 {
     try
     {
@@ -289,7 +289,7 @@
                         entry("ERROR=%s", e.what()));
     }
 }
-void Handler::longPowerPressed(sdbusplus::message::message& msg)
+void Handler::longPowerPressed(sdbusplus::message::message& /* msg */)
 {
     try
     {
@@ -302,7 +302,7 @@
     }
 }
 
-void Handler::resetPressed(sdbusplus::message::message& msg)
+void Handler::resetPressed(sdbusplus::message::message& /* msg */)
 {
     try
     {
@@ -315,7 +315,7 @@
     }
 }
 
-void Handler::idPressed(sdbusplus::message::message& msg)
+void Handler::idPressed(sdbusplus::message::message& /* msg */)
 {
     std::string groupPath{ledGroupBasePath};
     groupPath += ID_LED_GROUP;
diff --git a/src/button_handler_main.cpp b/src/button_handler_main.cpp
index e9fcc27..e71f8e4 100644
--- a/src/button_handler_main.cpp
+++ b/src/button_handler_main.cpp
@@ -1,6 +1,6 @@
 #include "button_handler.hpp"
 
-int main(int argc, char* argv[])
+int main(void)
 {
     auto bus = sdbusplus::bus::new_default();
 
diff --git a/src/gpio.cpp b/src/gpio.cpp
index 86d4cec..52ffed6 100644
--- a/src/gpio.cpp
+++ b/src/gpio.cpp
@@ -203,14 +203,15 @@
     }
     else if ((gpioDirection == "both"))
     {
-        // Before set gpio configure as an interrupt pin, need to set direction
-        // as 'in' or edge can't set as 'rising', 'falling' and 'both'
-        const char* in_direction = "in";
         devPath = gpioDev + "/gpio" + std::to_string(gpioNum) + "/direction";
 
         stream.open(devPath, std::fstream::out);
         try
         {
+            // Before set gpio configure as an interrupt pin, need to set
+            // direction as 'in' or edge can't set as 'rising', 'falling' and
+            // 'both'
+            const char* in_direction = "in";
             stream << in_direction;
             stream.close();
         }
diff --git a/src/hostSelector_switch.cpp b/src/hostSelector_switch.cpp
index c3ad83f..dbdd836 100644
--- a/src/hostSelector_switch.cpp
+++ b/src/hostSelector_switch.cpp
@@ -37,7 +37,7 @@
 void HostSelector::setInitialHostSelectorValue()
 {
     char buf;
-    for (int index = 0; index < gpioLineCount; index++)
+    for (size_t index = 0; index < gpioLineCount; index++)
     {
         auto result = ::lseek(config.gpios[index].fd, 0, SEEK_SET);
 
@@ -94,7 +94,8 @@
  * init() function can be created to override the default event handling
  */
 
-void HostSelector::handleEvent(sd_event_source* es, int fd, uint32_t revents)
+void HostSelector::handleEvent(sd_event_source* /* es */, int fd,
+                               uint32_t /* revents */)
 {
     int n = -1;
     char buf = '0';
diff --git a/src/id_button.cpp b/src/id_button.cpp
index 71e8539..99fd27f 100644
--- a/src/id_button.cpp
+++ b/src/id_button.cpp
@@ -24,7 +24,8 @@
     pressed();
 }
 
-void IDButton::handleEvent(sd_event_source* es, int fd, uint32_t revents)
+void IDButton::handleEvent(sd_event_source* /* es */, int fd,
+                           uint32_t /* revents */)
 {
     int n = -1;
     char buf = '0';
diff --git a/src/main.cpp b/src/main.cpp
index 624c9e7..5288635 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -26,7 +26,7 @@
 using namespace phosphor::logging;
 nlohmann::json gpioDefs;
 
-int main(int argc, char* argv[])
+int main(void)
 {
     int ret = 0;
 
diff --git a/src/power_button.cpp b/src/power_button.cpp
index 2446d7b..b6a89b9 100644
--- a/src/power_button.cpp
+++ b/src/power_button.cpp
@@ -39,7 +39,8 @@
     return pressedTime;
 }
 
-void PowerButton::handleEvent(sd_event_source* es, int fd, uint32_t revents)
+void PowerButton::handleEvent(sd_event_source* /* es */, int fd,
+                              uint32_t /* revents */)
 {
     int n = -1;
     char buf = '0';
diff --git a/src/reset_button.cpp b/src/reset_button.cpp
index c3e467e..03430f9 100644
--- a/src/reset_button.cpp
+++ b/src/reset_button.cpp
@@ -26,7 +26,8 @@
     pressed();
 }
 
-void ResetButton::handleEvent(sd_event_source* es, int fd, uint32_t revents)
+void ResetButton::handleEvent(sd_event_source* /* es */, int fd,
+                              uint32_t /* revents */)
 {
     int n = -1;
     char buf = '0';