users/

lib.rs

#![warn(missing_copy_implementations)]
#![warn(missing_docs)]
#![warn(nonstandard_style)]
#![warn(trivial_numeric_casts)]
#![warn(unreachable_pub)]
#![warn(unused)]


//! This is a library for getting information on Unix users and groups. It
//! supports getting the system users, and creating your own mock tables.
//!
//! In Unix, each user has an individual *user ID*, and each process has an
//! *effective user ID* that says which user’s permissions it is using.
//! Furthermore, users can be the members of *groups*, which also have names and
//! IDs. This functionality is exposed in libc, the C standard library, but as
//! an unsafe Rust interface. This wrapper library provides a safe interface,
//! using [`User`](struct.user.html) and [`Group`](struct.group.html) types
//! and functions such as [`get_user_by_uid`](fn.get_user_by_uid.html) instead
//! of low-level pointers and strings. It also offers basic caching
//! functionality.
//!
//! It does not (yet) offer *editing* functionality; the values returned are
//! read-only.
//!
//!
//! ## Users
//!
//! The function [`get_current_uid`](fn.get_current_uid.html) returns a
//! `uid_t` value representing the user currently running the program, and the
//! [`get_user_by_uid`](fn.get_user_by_uid.html) function scans the users
//! database and returns a `User` with the user’s information. This function
//! returns `None` when there is no user for that ID. The `uid_t` type is
//! re-exported from the libc crate.
//!
//! A [`User`](struct.User.html) value has the following accessors:
//!
//! - **uid:** The user’s ID
//! - **name:** The user’s name
//! - **primary_group:** The ID of this user’s primary group
//!
//! Here is a complete example that prints out the current user’s name:
//!
//! ```
//! use users::{get_user_by_uid, get_current_uid};
//!
//! let user = get_user_by_uid(get_current_uid()).unwrap();
//! println!("Hello, {}!", user.name().to_string_lossy());
//! ```
//!
//! This code assumes (with `unwrap()`) that the user hasn’t been deleted after
//! the program has started running. For arbitrary user IDs, this is **not** a
//! safe assumption: it’s possible to delete a user while it’s running a
//! program, or is the owner of files, or for that user to have never existed.
//! So always check the return values!
//!
//! There is also a [`get_current_username`](fn.get_current_username.html)
//! function, as it’s such a common operation that it deserves special
//! treatment.
//!
//!
//! ## Caching
//!
//! Despite the above warning, the users and groups database rarely changes.
//! While a short program may only need to get user information once, a
//! long-running one may need to re-query the database many times, and a
//! medium-length one may get away with caching the values to save on redundant
//! system calls.
//!
//! For this reason, this crate offers a caching interface to the database,
//! which offers the same functionality while holding on to every result,
//! caching the information so it can be re-used.
//!
//! To introduce a cache, create a new
//! [`UsersCache`](cache/struct.UsersCache.html). It has functions with the
//! same names as the ones from earlier. For example:
//!
//! ```
//! use users::{Users, Groups, UsersCache};
//!
//! let mut cache = UsersCache::new();
//! let uid = cache.get_current_uid();
//! let user = cache.get_user_by_uid(uid).unwrap();
//! println!("Hello again, {}!", user.name().to_string_lossy());
//! ```
//!
//! This cache is **only additive**: it’s not possible to drop it, or erase
//! selected entries, as when the database may have been modified, it’s best to
//! start entirely afresh. So to accomplish this, just start using a new
//! `UsersCache`.
//!
//!
//! ## Groups
//!
//! Finally, it’s possible to get groups in a similar manner.
//! A [`Group`](struct.Group.html) has the following accessors:
//!
//! - **gid:** The group’s ID
//! - **name:** The group’s name
//!
//! And again, a complete example:
//!
//! ```no_run
//! use users::{Users, Groups, UsersCache};
//!
//! let mut cache = UsersCache::new();
//! let group = cache.get_group_by_name("admin").expect("No such group 'admin'!");
//! println!("The '{}' group has the ID {}", group.name().to_string_lossy(), group.gid());
//! ```
//!
//!
//! ## Logging
//!
//! The `logging` feature, which is on by default, uses the `log` crate to
//! record all interactions with the operating system.
//!
//!
//! ## Caveats
//!
//! You should be prepared for the users and groups tables to be completely
//! broken: IDs shouldn’t be assumed to map to actual users and groups, and
//! usernames and group names aren’t guaranteed to map either!
//!
//! Use the [`mock`](mock/index.html) module to create custom tables to test
//! your code for these edge cases.


extern crate libc;
pub use libc::{uid_t, gid_t};

mod base;
pub use base::{User, Group, os};
pub use base::{get_user_by_uid, get_user_by_name};
pub use base::{get_group_by_gid, get_group_by_name};
pub use base::{get_current_uid, get_current_username};
pub use base::{get_effective_uid, get_effective_username};
pub use base::{get_current_gid, get_current_groupname};
pub use base::{get_effective_gid, get_effective_groupname};
pub use base::{get_user_groups, group_access_list};
pub use base::{all_users};

#[cfg(feature = "cache")]
pub mod cache;

#[cfg(feature = "cache")]
pub use cache::UsersCache;

#[cfg(feature = "mock")]
pub mod mock;

pub mod switch;

mod traits;
pub use traits::{Users, Groups};