Re: [PATCH v3 1/3] selftests/mm/write_to_hugetlbfs: parse -s as size_t

Li Wang
2025-12-23T02:41:43Z

Andrew Morton <akpm@linux-foundation.org> wrote:

> > > It is best to use strtoul() and check the 'end' character is '\0'.
> >
> > Hmm, that sounds like we need to go back to the patch V1 [1] method.
> > But I am not sure, @Andrew Morton, do you think so?
> >
> > --- a/tools/testing/selftests/mm/write_to_hugetlbfs.c
> > +++ b/tools/testing/selftests/mm/write_to_hugetlbfs.c
> > @@ -86,10 +86,17 @@ int main(int argc, char **argv)
> > while ((c = getopt(argc, argv, "s:p:m:owlrn")) != -1) {
> > switch (c) {
> > case 's':
> > - if (sscanf(optarg, "%zu", &size) != 1) {
> > - perror("Invalid -s.");
> > + char *end = NULL;
> > + unsigned long tmp = strtoul(optarg, &end, 10);
> > + if (errno || end == optarg || *end != '\0') {
> > + perror("Invalid -s size");
> > exit_usage();
> > }
> > + if (tmp == 0) {
> > + perror("size not found");
> > + exit_usage();
> > + }
> > + size = (size_t)tmp;
> > break;
> > case 'p':
>
> Geeze guys, it's just a selftest.
>
> hp2:/usr/src/linux-6.19-rc1> grep -r scanf tools/testing/selftests | wc -l
> 177
>
> if your command line breaks the selftest, fix your command line?

Yes, I am ok with sscanf() :-).

In fact, write_to hugetlbfs currently only accepts arguments from
charge_reserved_hugetlb.sh, and the way the '-s' is used is not
very diverse.

--
Regards,
Li Wang