[PATCH libdrm 3/3] xf86drm: replace stat() with access() to verify file existence

[Emil Velikov]

On 26 March 2018 at 11:26, Eric Engestrom <eric.engestrom at imgtec.com> wrote:
> Signed-off-by: Eric Engestrom <eric.engestrom at imgtec.com>
> ---
>  xf86drm.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/xf86drm.c b/xf86drm.c
> index 5701952ae83634b47628..47a82407df82d37a59b2 100644
> --- a/xf86drm.c
> +++ b/xf86drm.c
> @@ -3767,10 +3767,8 @@ int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device)
>          return -EINVAL;
>
>      n = snprintf(node, PATH_MAX, dev_name, DRM_DIR_NAME, min - base);
> -    if (n == -1 || n >= PATH_MAX)
> +    if (n == -1 || n >= PATH_MAX || access(node, F_OK))
>        return -errno;
> -    if (stat(node, &sbuf))
> -        return -EINVAL;
>
Above all - there's a beefy RATIONALE section in man 3p access and I'm
wondering if 2) isn't applicable in some odd corner case.
If things are safe - please a) document why - perf./other reasons and
b) update the other instances.

-Emil