On Sun, 7 Jan 2024 18:28:52 +0200
Petre Rodan <petre.rodan@xxxxxxxxxxxxxxx> wrote:
> Hi Jonathan,
>
> On Sun, Jan 07, 2024 at 03:53:33PM +0000, Jonathan Cameron wrote:
> > On Thu, 4 Jan 2024 12:12:45 +0200
> > Petre Rodan <petre.rodan@xxxxxxxxxxxxxxx> wrote:
> >
> > > Fix code flow problem and floating point exception caused by improper
> > > directory stream positioning.
> > >
> > > Fixes: <e58537ccce733> ("staging: iio: update example application.")
> > > Signed-off-by: Petre Rodan <petre.rodan@xxxxxxxxxxxxxxx>
> > Hi Petre,
> >
> > This doesn't really explain 'why' seeekdir(dp, 0) is wrong.
> > My assumption is that telldir() would not have returned 0 on this particular
> > system? Could you confirm that and update the message to explain why
> > seekdir(dp, 0) is not equivalent to rewinddir(dp).
>
> it looks like there is a 32-bit specific bug in one of the glibc patches that
> the stable Gentoo Linux is using [1]. telldir returns (u32)(-1) if seekdir is
> used which ends up in a floating point exception.
>
> it so happens that the rewinddir() function (which is equivalent) works
> correctly. so it is a fix for Gentoo users and should not impact anyone else.
>
> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=31212
>
> my very best regards,
> peter
I'd be happy to take the same change as a cleanup if you want to resubmit it
with a different patch description.
Thanks,
Jonathan
>
> > Thanks,
> >
> > Jonathan
> >
> > > ---
> > > tools/iio/iio_utils.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/tools/iio/iio_utils.c b/tools/iio/iio_utils.c
> > > index 6a00a6eecaef..c5c5082cb24e 100644
> > > --- a/tools/iio/iio_utils.c
> > > +++ b/tools/iio/iio_utils.c
> > > @@ -376,7 +376,7 @@ int build_channel_array(const char *device_dir, int buffer_idx,
> > > goto error_close_dir;
> > > }
> > >
> > > - seekdir(dp, 0);
> > > + rewinddir(dp);
> > > while (ent = readdir(dp), ent) {
> > > if (strcmp(ent->d_name + strlen(ent->d_name) - strlen("_en"),
> > > "_en") == 0) {
> > > --
> > > 2.41.0
