[PATCH wayland] cursor: Use shm_open() instead of XDG_RUNTIME_DIR files

[Matt Hoosier]

On Wed, Oct 18, 2017 at 4:23 AM, Quentin Glidic
<sardemff7+wayland at sardemff7.net> wrote:
> +       fd = shm_open("/wayland-cursor-shared", O_CREAT | O_RDWR, 0);
> +       shm_unlink("/wayland-cursor-shared");

This seems to be a departure from the anonymous behavior that
mkstemp() previously offered. shm_open() says that it will open an
existing shared-memory object if that pathname already exists. Isn't
there a race between one thread doing shm_open() and a different
thread doing shm_unlink() such that you could accidentally end up with
two different filedescriptors pointing at the same SHM object?