[PATCH] Improve test coverage of strnlen function

[Noah Goldstein]

On Wed, Jun 2, 2021 at 1:26 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Wed, Jun 2, 2021 at 12:13 PM Sunil K Pandey via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
> >
> > This patch covers the following condition:
> >
> > Strings start with different alignments and end with less than 512 byte
> > length.
> > ---
> >  string/test-strnlen.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/string/test-strnlen.c b/string/test-strnlen.c
> > index d70faa26ab..20e645893a 100644
> > --- a/string/test-strnlen.c
> > +++ b/string/test-strnlen.c
> > @@ -271,6 +271,10 @@ test_main (void)
> >        do_test (1, 1 << i, 5000, BIG_CHAR);
> >      }
> >
> > +  for (i = 1; i <= 127; i++)
>
> I think it makes sense to either include 0 or 128 for alignments
> as in some implementations (x86 avx2/evex for example)
> that is a unique case.
>
> > +    for (size_t length = i; length < 512; length++)
> > +      do_test (i, length, 512, BIG_CHAR);
I think it would also make sense to include multiple length.
Again in the x86_64 avx2/evex implementations for example
there are 4 cases for handling remaining length:
 [1,32], [33,64], [65,96], and [97, 128].

As well it might be useful to have tests for position of
null > length as well.

>
> Might be strengthened a bit with additional test case
> in inner loop:
> do_test (getpagesize() - i, length, 512, BIG_CHAR);
>
> > +
> >    do_random_tests ();
> >    do_page_tests ();
> >    do_page_2_tests ();
> > --
> > 2.31.1
> >