int ul_dbuff_strcpy(ul_dbuff_t *buf, const char *str);
int ul_dbuff_strcat(ul_dbuff_t *buf, const char *str);
int ul_dbuff_append_byte(ul_dbuff_t *buf, unsigned char b);
int ul_dbuff_strcpy(ul_dbuff_t *buf, const char *str);
int ul_dbuff_strcat(ul_dbuff_t *buf, const char *str);
int ul_dbuff_append_byte(ul_dbuff_t *buf, unsigned char b);