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

Mark Wielaard mark@klomp.org
Tue Oct 27 22:19:11 GMT 2020


Hi Rich,

On Tue, Oct 27, 2020 at 01:08:17PM -0400, Rich Felker wrote:
> On Tue, Oct 27, 2020 at 04:04:44PM +0100, Mark Wielaard wrote:
> > Right, it is also adopted by zsh and some other shells. The big-O
> > properties don't really matter in this case because fnmatch is used on
> > small input strings like file names (or in this case section names).
> 
> They do because they're also in space, unless you want
> exponential-time which is huge even on small inputs, and greater than
> O(1) space requirement means the interface can't satisfy its contract
> to return a conclusive result for valid inputs.

But that isn't the contract if fnmatch. fnmatch returns 0 for a match
and non-zero for either a non-match or some error. So if your
algorithm hits some error case, like out of memory, returning a
non-zero result is fine.

I believe the extended wildcard pattern are widely supported and
useful. If you don't want to implement them because they aren't in any
standardized enough yet we can ask the Austin Group to add them to
fnmatch. They have adopted other GNU flags for fnmatch in the past.

Cheers,

Mark


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