rustix

Safe Rust bindings to POSIX/Unix/Linux/Winsock2 syscalls

A Bytecode Alliance project

Github Actions CI Status zulip chat crates.io page docs.rs docs

`rustix` provides efficient memory-safe and [I/O-safe] wrappers to POSIX-like, Unix-like, Linux, and Winsock2 syscall-like APIs, with configurable backends. It uses Rust references, slices, and return values instead of raw pointers, and [I/O safety types] instead of raw file descriptors, providing memory safety, [I/O safety], and [provenance]. It uses `Result`s for reporting errors, [`bitflags`] instead of bare integer flags, an [`Arg`] trait with optimizations to efficiently accept any Rust string type, and several other efficient conveniences. `rustix` is low-level and, and while the `net` API supports Winsock2 on Windows, the rest of the APIs do not support Windows; for higher-level and more portable APIs built on this functionality, see the [`cap-std`], [`memfd`], [`timerfd`], and [`io-streams`] crates, for example. `rustix` currently has two backends available: * linux_raw, which uses raw Linux system calls and vDSO calls, and is supported on Linux on x86-64, x86, aarch64, riscv64gc, powerpc64le, arm (v5 onwards), mipsel, and mips64el, with stable, nightly, and 1.63 Rust. - By being implemented entirely in Rust, avoiding `libc`, `errno`, and pthread cancellation, and employing some specialized optimizations, most functions compile down to very efficient code, which can often be fully inlined into user code. - Most functions in `linux_raw` preserve memory, I/O safety, and pointer provenance all the way down to the syscalls. * libc, which uses the [`libc`] crate which provides bindings to native `libc` libraries on Unix-family platforms, and [`windows-sys`] for Winsock2 on Windows, and is portable to many OS's. The linux_raw backend is enabled by default on platforms which support it. To enable the libc backend instead, either enable the "use-libc" cargo feature, or set the `RUSTFLAGS` environment variable to `--cfg=rustix_use_libc` when building. ## Cargo features The modules [`rustix::io`], [`rustix::fd`], and [`rustix::ffi`] are enabled by default. The rest of the API is conditional with cargo feature flags: | Name | Description | ---------- | --------------------- | `event` | [`rustix::event`]—Polling and event operations. | `fs` | [`rustix::fs`]—Filesystem operations. | `io_uring` | [`rustix::io_uring`]—Linux io_uring. | `mm` | [`rustix::mm`]—Memory map operations. | `mount` | [`rustix::mount`]—Linux mount API. | `net` | [`rustix::net`]—Network-related operations. | `param` | [`rustix::param`]—Process parameters. | `pipe` | [`rustix::pipe`]—Pipe operations. | `process` | [`rustix::process`]—Process-associated operations. | `procfs` | [`rustix::procfs`]—Utilities for reading `/proc` on Linux. | `pty` | [`rustix::pty`]—Pseudoterminal operations. | `rand` | [`rustix::rand`]—Random-related operations. | `stdio` | [`rustix::stdio`]—Stdio-related operations. | `system` | [`rustix::system`]—System-related operations. | `termios` | [`rustix::termios`]—Terminal I/O stream operations. | `thread` | [`rustix::thread`]—Thread-associated operations. | `time` | [`rustix::time`]—Time-related operations. | | | `use-libc` | Enable the libc backend. [`rustix::event`]: https://docs.rs/rustix/*/rustix/fs/index.html [`rustix::fs`]: https://docs.rs/rustix/*/rustix/fs/index.html [`rustix::io_uring`]: https://docs.rs/rustix/*/rustix/io_uring/index.html [`rustix::mm`]: https://docs.rs/rustix/*/rustix/mm/index.html [`rustix::mount`]: https://docs.rs/rustix/*/rustix/mount/index.html [`rustix::net`]: https://docs.rs/rustix/*/rustix/net/index.html [`rustix::param`]: https://docs.rs/rustix/*/rustix/param/index.html [`rustix::pipe`]: https://docs.rs/rustix/*/rustix/pipe/index.html [`rustix::process`]: https://docs.rs/rustix/*/rustix/process/index.html [`rustix::procfs`]: https://docs.rs/rustix/*/rustix/procfs/index.html [`rustix::pty`]: https://docs.rs/rustix/*/rustix/pty/index.html [`rustix::rand`]: https://docs.rs/rustix/*/rustix/rand/index.html [`rustix::stdio`]: https://docs.rs/rustix/*/rustix/stdio/index.html [`rustix::system`]: https://docs.rs/rustix/*/rustix/system/index.html [`rustix::termios`]: https://docs.rs/rustix/*/rustix/termios/index.html [`rustix::thread`]: https://docs.rs/rustix/*/rustix/thread/index.html [`rustix::time`]: https://docs.rs/rustix/*/rustix/time/index.html [`rustix::io`]: https://docs.rs/rustix/*/rustix/io/index.html [`rustix::fd`]: https://docs.rs/rustix/*/rustix/fd/index.html [`rustix::ffi`]: https://docs.rs/rustix/*/rustix/ffi/index.html ## 64-bit Large File Support (LFS) and Year 2038 (y2038) support `rustix` automatically uses 64-bit APIs when available, and avoids exposing 32-bit APIs that would have the year-2038 problem or fail to support large files. For instance, `rustix::fstatvfs` calls `fstatvfs64`, and returns a struct that's 64-bit even on 32-bit platforms. ## Similar crates `rustix` is similar to [`nix`], [`simple_libc`], [`unix`], [`nc`], and [`uapi`]. `rustix` is architected for [I/O safety] with most APIs using [`OwnedFd`] and [`AsFd`] to manipulate file descriptors rather than `File` or even `c_int`, and supporting multiple backends so that it can use direct syscalls while still being usable on all platforms `libc` supports. Like `nix`, `rustix` has an optimized and flexible filename argument mechanism that allows users to use a variety of string types, including non-UTF-8 string types. [`relibc`] is a similar project which aims to be a full "libc", including C-compatible interfaces and higher-level C/POSIX standard-library functionality; `rustix` just aims to provide safe and idiomatic Rust interfaces to low-level syscalls. `relibc` also doesn't tend to support features not supported on Redox, such as `*at` functions like `openat`, which are important features for `rustix`. `rustix` has its own code for making direct syscalls, similar to the [`syscall`], [`sc`], and [`scall`] crates, using the Rust `asm!` macro. `rustix` can also use Linux's vDSO mechanism to optimize Linux `clock_gettime` on all architectures, and all Linux system calls on x86. And `rustix`'s syscalls report errors using an optimized `Errno` type. `rustix`'s `*at` functions are similar to the [`openat`] crate, but `rustix` provides them as free functions rather than associated functions of a `Dir` type. `rustix`'s `CWD` constant exposes the special `AT_FDCWD` value in a safe way, so users don't need to open `.` to get a current-directory handle. `rustix`'s `openat2` function is similar to the [`openat2`] crate, but uses I/O safety types rather than `RawFd`. `rustix` does not provide dynamic feature detection, so users must handle the [`NOSYS`] error themselves. `rustix`'s `termios` module is similar to the [`termios`] crate, but uses I/O safety types rather than `RawFd`, and the flags parameters to functions such as `tcsetattr` are `enum`s rather than bare integers. And, rustix calls its `tcgetattr` function `tcgetattr`, rather than `Termios::from_fd`. ## Minimum Supported Rust Version (MSRV) This crate currently works on the version of [Rust on Debian stable], which is currently Rust 1.63. This policy may change in the future, in minor version releases, so users using a fixed version of Rust should pin to a specific version of this crate. [Rust on Debian stable]: https://packages.debian.org/stable/rust/rustc [`nix`]: https://crates.io/crates/nix [`unix`]: https://crates.io/crates/unix [`nc`]: https://crates.io/crates/nc [`simple_libc`]: https://crates.io/crates/simple_libc [`uapi`]: https://crates.io/crates/uapi [`relibc`]: https://github.com/redox-os/relibc [`syscall`]: https://crates.io/crates/syscall [`sc`]: https://crates.io/crates/sc [`scall`]: https://crates.io/crates/scall [`openat`]: https://crates.io/crates/openat [`openat2`]: https://crates.io/crates/openat2 [I/O safety types]: https://doc.rust-lang.org/stable/std/os/fd/index.html#structs [`termios`]: https://crates.io/crates/termios [`libc`]: https://crates.io/crates/libc [`windows-sys`]: https://crates.io/crates/windows-sys [`cap-std`]: https://crates.io/crates/cap-std [`memfd`]: https://crates.io/crates/memfd [`timerfd`]: https://crates.io/crates/timerfd [`io-streams`]: https://crates.io/crates/io-streams [`bitflags`]: https://crates.io/crates/bitflags [`Arg`]: https://docs.rs/rustix/*/rustix/path/trait.Arg.html [I/O-safe]: https://github.com/rust-lang/rfcs/blob/master/text/3128-io-safety.md [I/O safety]: https://github.com/rust-lang/rfcs/blob/master/text/3128-io-safety.md [provenance]: https://github.com/rust-lang/rust/issues/95228 [`OwnedFd`]: https://doc.rust-lang.org/stable/std/os/fd/struct.OwnedFd.html [`AsFd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.AsFd.html [`NOSYS`]: https://docs.rs/rustix/*/rustix/io/struct.Errno.html#associatedconstant.NOSYS