Re: [PATCH] implement glibc's glob_pattern_p

[Glauber Costa <glommer@cloudius-systems.com>]

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On Mon, Jul 21, 2014 at 6:33 PM, Rich Felker <dalias@libc.org> wrote:

> On Thu, Jul 17, 2014 at 01:12:55PM +0400, Glauber Costa wrote:
> > Currently, glob is implemented but glob_pattern_p is not. This function
> > can trivially be implemented with existing glob machinery, since all it
> > does is to tell whether or not the string contains special symbols. This
> > is basically the same logic as is_literal, but with inverted return
> value.
> >
> > The value of the "quote" parameter should also be inverted, since the man
> > page states that when the quote parameter is *non*-zero, then backslashes
> > are ignored. is_literal ignores them when useesc is *zero*.
>
> Upon reviewing this patch, I'm not sure if it's correct. It wrote this
> code (glob.c) roughly 10 years ago and barely touched it since, but
> from what I can tell, the existing is_literal looks like a premature
> optimization to avoid calling fnmatch when it's not necessary than an
> accurate predicate. In other words, it's designed to reliably return 0
> if the string is a glob, but there are also cases where it returns 0
> when the string is not a "glob pattern" but not purely a literal
> either (e.g. anything containing backslash when useesc is nonzero,
> since such strings cannot be processed with strcmp and need fnmatch).
>
> My leaning would be to remove this "optimization" from glob.c entirely
> (it shouldn't be needed if fnmatch is efficient) and move the code to
> a separate file for glob_pattern_p, but then we need to make sure it
> gets things right with no false positives or false negatives.
>
> Hi

I will come back to this soon, then.

Cya

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