chg: verify XDG_RUNTIME_DIR According to the specification [1], $XDG_RUNTIME_DIR should be ignored unless: The directory MUST be owned by the user, and he MUST be the only one having read and write access to it. Its Unix access mode MUST be 0700. This patch adds a check and ignores it if it does not meet part of the criteria. [1]: https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html