Re: Weirdness with stat()

[Jim Hull <imaginos@imaginos.net>]

Very good. thanks.

		Jim

On Tue, 4 Jul 2000, Steve Schlaifer wrote:

> On Tue, 4 Jul 2000, Jim Hull wrote:
> > [...]
> >
> > struct stat *st;
> > 
> >    stat(CONFIG, st);
> >    if ((st->st_uid != 0) || (st->st_mode != 33152)) {
> >       fprintf(stderr, "Unsecure modes on configuration files\n");
> >       exit(1);
> >    }
> > 
> > This worked with absolutly no problems on my laptop. I went to run it on
> > my desktop (2.4.0-test2 SMP) and it started segfaulting. It wasn't
> > segfaulting at the stat() call, it was segfaulting in weird places like a
> > syslog() or a execv().
> > 
> > [...]
> >
> > Would this be my poor implementation of stat, or would this actually be a
> > kernel bug.
> 
> Neither, this is a bad use of stat.  In this case, st is an uninitialized
> pointer and you are having stat treat that as a pointer to some random
> location in memory which it dutifully fills with the stat information.
> Change your code to
> 
> struct stat st;              /* note not *st, just st */
> 
> stat(CONFIG, &st);           /* note &st not st */
> 
> and things will get much better.
> 
> 		--Steve
> 
>   "We have a government of law, and government officials must
>   be held accountable under the law."
> 
>     -- Judge Royce Lamberth
>        U.S. District Court for the District of Columbia
> 


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