Date: Wed, 13 Aug 2014 11:14:06 -0600 From: Ian Lepore <ian@FreeBSD.org> To: "Sam Fourman Jr." <sfourman@gmail.com> Cc: hackers@freebsd.org Subject: Re: sysctl(3) question Message-ID: <1407950046.56408.513.camel@revolution.hippie.lan> In-Reply-To: <CAOFF%2BZ2y3W7d1EL0PcEQCy28i1oOXDTDhW8z4UyfBUiHgkk6Jg@mail.gmail.com> References: <CAOFF%2BZ2y3W7d1EL0PcEQCy28i1oOXDTDhW8z4UyfBUiHgkk6Jg@mail.gmail.com>
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On Wed, 2014-08-13 at 12:00 -0500, Sam Fourman Jr. wrote:
> Hello Hackers,
>
> the following command gives me the disks in a system
> sysctl kern.disks
> kern.disks: cd0 ada0
>
>
> my question is, what paramaters and values do I have to pass sysctl(3) to
> give me those disks?
>
>
>
> I have tried and I cant get HW_DISKNAMES from <sys/sysctl.h> to work
>
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <sys/param.h>
> #include <sys/sysctl.h>
> #include <err.h>
>
> int main(void) {
>
> int mib[2];
> size_t len;
> char *p;
>
> mib[0] = CTL_HW;
> mib[1] = HW_DISKNAMES;
>
> /* Determine how much space to allocate. */
> if (sysctl(mib, 2, NULL, &len, NULL, 0) == -1)
> err(1, "sysctl");
>
> if ((p = (char *)malloc(len)) == NULL)
> err(1, NULL);
>
> /* Populate the allocated area with the string returned
> * * by sysctl.
> * */
> if (sysctl(mib, 2, p, &len, NULL, 0) == -1)
> err(1, "sysctl");
>
> printf("%s\n", p);
>
> return 0;
> }
>
> Sam Fourman Jr.
It looks like the HW_DISKNAMES oid is obsolete and the docs and header
file never got updated to reflect that.
The new disks list uses OID_AUTO rather than a fixed number, so use
sysctlbyname(3) to access it.
-- Ian
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