Date: Wed, 17 Mar 2004 11:01:46 +0100 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Soeren Straarup <xride@x12.dk> Cc: freebsd-geom@freebsd.org Subject: Re: A simple C program to read out info from geom Message-ID: <5673.1079517706@critter.freebsd.dk> In-Reply-To: Your message of "Wed, 17 Mar 2004 10:12:31 %2B0100." <20040317100531.R68939-100000@x12.dk>
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In message <20040317100531.R68939-100000@x12.dk>, Soeren Straarup writes:
>
>Hi
>I'm trying to get into the geom some more by writting and testing,
>but i'm stuck here, i'm trying to look at the first item in the snap
>shot, using libgeom.h from userland.
><program>
>#include <libgeom.h>
>#include <stdio.h>
>#include <sys/resource.h>
>#include <devstat.h>
>#include <sys/devicestat.h>
>
>
>int main ( void )
>{
> char *p;
> struct gmesh gmp;
> struct devstat *gsp;
> struct gprovider *pp;
> struct gconsumer *cp;
> struct gident *gid;
> void *sp;
>
> geom_gettree(&gmp);
You lack a geom_stats_open() here.
> sp = geom_stats_snapshot_get();
> gsp = geom_stats_snapshot_next(sp);
gsp is returned as NULL here to tell you about the problem.
> gid = geom_lookupid(&gmp, gsp->id);
Here you dereference a NULL pointer, and get a core dump.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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