A Bytecode Alliance project
posish provides efficient memory-safe and I/O-safe wrappers to "POSIX-ish"
libc APIs and syscalls.
posish is relatively low-level and does not support Windows; for higher-level
and portable APIs to this functionality, see the system-interface,
cap-std, and fs-set-times crates.
Linux raw syscall support
On Linux, posish can optionally be configured to use the raw Linux syscall
ABI directly instead of libc. To enable this, use Rust nightly, and set the
RUSTFLAGS environment variable to --cfg linux_raw, or otherwise pass
--cfg linux_raw to rustc. This mode is new, and so far only supports x86-64,
x86, and aarch64, but a fair amount of code has been successfully adapted to
use it, and ports to most other architectures should be straightforward.
This feature is fun in two ways:
- By being implemented entirely in Rust, avoiding
libc,errno, and pthread cancellation, and using type layout optimizations and an optimized error type, most functions compile down to very simple code and can even be fully inlined into user code. - Memory buffers are kept in Rust slices, out parameters are returned as
regular values, and file descriptors are kept in
io-lifetimestypes, so most functions preserve memory safety and I/O safety all the way down to the syscalls.