[libcamera-devel] [PATCH 09/10] android: metadata: Prevent variable aliasing

[Laurent Pinchart]

On Wed, Oct 14, 2020 at 02:42:07PM +0200, Niklas Söderlund wrote:
> On 2020-10-13 16:12:40 +0100, Kieran Bingham wrote:
> > The validate_camera_metadata_structure() call uses two instances of a
> > variable named aligned_ptr().
> > 
> > Reuse the first instance which is not otherwise re-used for the second
> > scoped usage.
> > 
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > ---
> > *** This is in android metadata library code ***
> > 
> > This is only here as a temporary repair. Ideally we shouldn't make changes to this code base.
> > disabling the warning on this library component is likely a better choice.
> > 
> >  src/android/metadata/camera_metadata.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/android/metadata/camera_metadata.c b/src/android/metadata/camera_metadata.c
> > index b86586a7e685..129d1e92ece1 100644
> > --- a/src/android/metadata/camera_metadata.c
> > +++ b/src/android/metadata/camera_metadata.c
> > @@ -433,7 +433,7 @@ int validate_camera_metadata_structure(const camera_metadata_t *metadata,
> >          };
> >  
> >          for (size_t i = 0; i < sizeof(alignments)/sizeof(alignments[0]); ++i) {
> > -            uintptr_t aligned_ptr = ALIGN_TO((uintptr_t) metadata + alignmentOffset,
> > +            aligned_ptr = ALIGN_TO((uintptr_t) metadata + alignmentOffset,
> 
> This is a tricky one. As you say ideally we should fix this upstream and 
> backport it. But being able to enable the build time warning of our own 
> code base would be really nice. As we already inject a SPDX header to 
> this file I see no real harm, with a patch submitted for upstream,
> 
> Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>

Alternatively we could disable the warning for the Android camera
metadata library.

> >                      alignments[i].alignment);
> >  
> >              if ((uintptr_t)metadata + alignmentOffset != aligned_ptr) {

-- 
Regards,

Laurent Pinchart