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