4.4 Logging handler

Data type: gcry_handler_log_t

This type is defined as: void (*gcry_handler_log_t) (void *, int, const char *, va_list)

Function: void gcry_set_log_handler (gcry_handler_log_t func_log, void *cb_data)

This function registers func_log as `logging handler', which means that it will be called in case Libgcrypt wants to log a message. This function may and should be used prior to calling gcry_check_version.