This small utility crate gets get the IANA time zone for the current system. This is also known the tz database, tzdata, the zoneinfo database and, the Olson database.
Example:
extern crate iana_time_zone;
println!("current: {}", iana_time_zone::get_timezone().unwrap());
You can test this is working on your platform with:
cargo test -- --nocapture