The helper function produces the value that is returned in *oldlenp.
If you happen to use CTL_DESCRIBE (e.g. running sysctl -d), it's
not your helper function being called but the sysctl_describe helper
that returns a value of 1024.
Maybe you can show your helper routine and how you call sysctl ?
sure, I call sysctl this way: sysctl debug.tslog
here's the helper function code:
static int
sysctl_debug_tslog(SYSCTLFN_ARGS)
{
char buf[LINE_MAX] = "";
char *where = oldp;
size_t slen, i, limit;
int error = 0;
static size_t needed = 0;
/* Come back with the right size */
/* here at second call, *oldlenp == 1024 */
if (*oldlenp < needed) {
*oldlenp = needed;
return 0; /* will be back with correct size */
}
/* Add data logged within the kernel. */
limit = MIN(nrecs, nitems(timestamps));
for (i = 0; i < limit; i++) {
snprintf(buf, LINE_MAX, "0x%x %llu",
timestamps[i].lid,
(unsigned long long)timestamps[i].tsc);
switch (timestamps[i].type) {
case TS_ENTER:
strcat(buf, " ENTER");
break;
case TS_EXIT:
strcat(buf, " EXIT");
break;
case TS_THREAD:
strcat(buf, " THREAD");
break;
case TS_EVENT:
strcat(buf, " EVENT");
break;
}
snprintf(buf, LINE_MAX, "%s %s", buf,
timestamps[i].f ? timestamps[i].f : "(null)");
if (timestamps[i].s)
snprintf(buf, LINE_MAX, "%s %s\n", buf,
timestamps[i].s);
else
strcat(buf, "\n");
slen = strlen(buf) + 1;
if (where == NULL) /* 1st pass, calculate needed */
needed += slen;
else {
if (i > 0)
where--; /* overwrite last \0 */
if ((error = copyout(buf, where, slen)))
break;
where += slen;
}
}
/* Come back with an address */
if (oldp == NULL)
*oldlenp = needed;
return error;
}
Here's the setup:
SYSCTL_SETUP(sysctl_tslog_setup, "tslog sysctl")
{
sysctl_createv(NULL, 0, NULL, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READONLY,
CTLTYPE_STRING, "tslog",
SYSCTL_DESCR("Dump recorded event timestamps"),
sysctl_debug_tslog, 0, NULL, 0,
CTL_DEBUG, CTL_CREATE, CTL_EOL);
}
--
------------------------------------------------------------------------
Emile `iMil' Heitor <imil@{home.imil.net,NetBSD.org}> | https://imil.net
