[PATCH] posix: Only check shm_unlink obj_err if necessary

[Gedare Bloom]

This looks fine for someone to push to master, along with the other one for 5.1

On Tue, Jan 28, 2020 at 11:37 AM Kinsey Moore <kinsey.moore at oarcorp.com> wrote:
>
> In the nominal case checked by spsysinit01, obj_err is unmodified if
> _POSIX_Shm_Get_by_name returns non-NULL. In the case of shm_unlink, this
> means an uninitialized value is passed into the switch and it appears
> this test was passing by virtue of the stack having the right value on
> it in most cases. This now checks obj_err only if _POSIX_Shm_Get_by_name
> returns NULL.
> ---
>  cpukit/posix/src/shmunlink.c | 45 ++++++++++++++++++------------------
>  1 file changed, 23 insertions(+), 22 deletions(-)
>
> diff --git a/cpukit/posix/src/shmunlink.c b/cpukit/posix/src/shmunlink.c
> index 00d743ac80..39c2ba0d87 100644
> --- a/cpukit/posix/src/shmunlink.c
> +++ b/cpukit/posix/src/shmunlink.c
> @@ -29,28 +29,29 @@ int shm_unlink( const char *name )
>    _Objects_Allocator_lock();
>
>    shm = _POSIX_Shm_Get_by_name( name, 0, &obj_err );
> -  switch ( obj_err ) {
> -    case OBJECTS_GET_BY_NAME_INVALID_NAME:
> -      err = ENOENT;
> -      break;
> -
> -    case OBJECTS_GET_BY_NAME_NAME_TOO_LONG:
> -      err = ENAMETOOLONG;
> -      break;
> -
> -    case OBJECTS_GET_BY_NAME_NO_OBJECT:
> -    default:
> -      _Objects_Namespace_remove_string(
> -        &_POSIX_Shm_Information,
> -        &shm->Object
> -      );
> -
> -      if ( shm->reference_count == 0 ) {
> -        /* Only remove the shm object if no references exist to it. Otherwise,
> -         * the shm object will be freed later in _POSIX_Shm_Attempt_delete */
> -        _POSIX_Shm_Free( shm );
> -      }
> -      break;
> +  if ( shm ) {
> +    _Objects_Namespace_remove_string(
> +      &_POSIX_Shm_Information,
> +      &shm->Object
> +    );
> +
> +    if ( shm->reference_count == 0 ) {
> +      /* Only remove the shm object if no references exist to it. Otherwise,
> +       * the shm object will be freed later in _POSIX_Shm_Attempt_delete */
> +      _POSIX_Shm_Free( shm );
> +    }
> +  } else {
> +    switch ( obj_err ) {
> +      case OBJECTS_GET_BY_NAME_NAME_TOO_LONG:
> +        err = ENAMETOOLONG;
> +        break;
> +
> +      case OBJECTS_GET_BY_NAME_INVALID_NAME:
> +      case OBJECTS_GET_BY_NAME_NO_OBJECT:
> +      default:
> +        err = ENOENT;
> +        break;
> +    }
>    }
>
>    _Objects_Allocator_unlock();
> --
> 2.20.1
>
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