[demo][linux] optimize elog_port_get_time

demo/os/linux/easylogger/port/elog_port.c

@@ -104,16 +104,14 @@ void elog_port_output_unlock(void) {
  */
 const char *elog_port_get_time(void) {
     static char cur_system_time[24] = { 0 };
-    time_t timep;
+
-    struct tm *p;
+    time_t cur_t;
-
+    struct tm cur_tm;
-    time(&timep);
+
-    p = localtime(&timep);
+    time(&cur_t);
-    if (p == NULL) {
+    localtime_r(&cur_t, &cur_tm);
-        return "";
+
-    }
+    strftime(cur_system_time, sizeof(cur_system_time), "%Y-%m-%d %T", &cur_tm);
-    snprintf(cur_system_time, 18, "%02d-%02d %02d:%02d:%02d", p->tm_mon + 1, p->tm_mday,
-            p->tm_hour, p->tm_min, p->tm_sec);
 
     return cur_system_time;
 }