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Re: buffer write bug in mg
- To: tech_(_at_)_openbsd_(_dot_)_org
- Subject: Re: buffer write bug in mg
- From: Han Boetes <han_(_at_)_mijncomputer_(_dot_)_nl>
- Date: Tue, 4 Apr 2006 22:52:33 +0200
- Mail-followup-to: tech_(_at_)_openbsd_(_dot_)_org
Kjell Wooding wrote:
> > From basename(3):
> > CAVEATS
> > basename() returns a pointer to internal static storage
> > space that will be overwritten by subsequent calls.
> That's the openbsd caveat. It's okay here, as we do an immediate
> The one you probably mean is the one that says "Both dirname and
> basename may modify the contents of path, so copies should be
> passed to these functions." which is specific to the linux POSIX
> basename (which you get when you include libgen)
> If you don't include libgen, you should get the glib version,
> which doesn't have this little evil behavior.
Ah right, I'm getting old, my memory is fading.
> > So I'd like to suggest this extra patch:
> Bleah. That would mean extra strdups wherever baseame and
> dirname are used. This isn't needed under OpenBSD, and you
> should be able to avoid it by avoiding the aforementioned
True, and that fixed it indeed.
> Does POSIX *actually* insist that basename and dirname MUST have
> evil side effects?
POSIX does not insist, but -- alas -- it also doesn't forbid this
The basename() function may modify the string pointed to by
path, and may return a pointer to static storage that may then
be overwritten by a subsequent call to basename().
Is this worth mentioning in the manpage?
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