Re: [musl] Re: [QUESTION] Which fnmatch() functionality does elfutils depend on?

[Rich Felker <dalias@libc.org>]

On Mon, Oct 26, 2020 at 02:28:59PM -0300, Érico Nogueira wrote:
> On Mon Oct 26, 2020 at 3:10 PM -03, Mark Wielaard wrote:
> > Hi Érico,
> >
> > On Mon, 2020-10-26 at 12:03 -0300, Érico Nogueira via Elfutils-devel
> > wrote:
> > > Do elfutils program actually depend on the extra functionality
> > > enabled by
> > > FNM_EXTMATCH? Is changing the flag to have no effect a "bug"?
> >
> > Yes. The extended wildcard pattern is relied upon by both
> > eu-strip with
> >
> > --keep-section=SECTION Keep the named section. SECTION is an
> > extended wildcard pattern. May be given
> > more than once.
> >
> > and eu-elfcompress with
> >
> > -n, --name=SECTION SECTION name to (de)compress, SECTION is an
> > extended wildcard pattern (defaults to
> > '.?(z)debug*')
> >
> > In the eu-strip case it might be reasoned that instead of a
> > wildcard pattern the user might most of the time simply provide
> > a section name as is (especially since the option may be given
> > multiple times). But in the case of eu-elfcompress the
> > program relies on the default SECTION name being an extended
> > wildcard pattern. So not supporting FNM_EXTMATCH breaks the
> > default functionality of eu-elfcompress.
> >
> > Cheers,
> >
> > Mark
> 
> Understood, thank you. I'm replying to the musl mailing list as well,
> then, to hopefully gather more opinions, since I don't know what the
> best way of solving this would be.

I'm pretty sure we don't want to adopt further fnmatch extensions like
this since they seem to affect the big-O's required to do matching and
preclude good algorithms. I like Max's solution here with multiple
patterns.

If elfutils really wants to keep using FNM_EXTMATCH it should probably
ship something like gnulib with a replacement fnmatch for systems that
don't have it.

Rich