fn parse_mountinfo_line(line: &str) -> Option<(PathBuf, String, String)>Expand description
Parses one /proc/self/mountinfo line into (mount_point, fs_type, source).
Format: <fields...> - <fs_type> <source> <options>, where fields before the - include the
mount point as the 5th whitespace-separated field, followed by zero or more optional fields
(shared:N, master:N, propagate_from:N, unbindable). The mount point’s fixed position
makes the optional field count irrelevant here. See proc(5).