Named mutex might not value permissions correctly

Hi!

When using a named_mutex within POSIX, and setting the Permissions Object, everything boils down to an ::sem_open call. There, the permissions are passed. But ::sem_open masks the permissions with the processes umask. Therefore, the semaphore might not have 0666 permissions, but e.g. 644, even though, permissions were passed with set_unrestricted().

Workaround there would be setting umask to 0 before ::sem_open, and restoring again after.
At least, this behaviour should be documented.

Regards,

Matthias

Comienza rastreando la ruta POSIX named_mutex hasta la llamada a ::sem_open descrita en el issue, centrándote en cómo interactúan los valores de Permissions Object con la umask del proceso. Confirma los permisos resultantes con set_unrestricted() y determina después si el resultado previsto es un cambio de comportamiento o la documentación de la limitación.

Escrito por el modelo de indexación a partir del texto del issue.