void ec_log_unregister(void);
/* same api than printf */
-int ec_log(unsigned int level, const char *format, ...);
+int ec_log(unsigned int level, const char *format, ...)
+ __attribute__((format(__printf__, 2, 3)));
+
int ec_vlog(unsigned int level, const char *format, va_list ap);
/* default log handler for the library, use printf */