IOB_PRE
(void) strlcpy(buf, IOB_PRE, bufsz);
(void) snprintf(buf, bufsz, "%s%llx", IOB_PRE, serid);
(void) snprintf(buf, bufsz, "%s%s", IOB_PRE, idstr);
#define iob_pre_len (sizeof (IOB_PRE) - 1)