Joseph Richey
db27e97d94
On Linux, we detect if `getrandom` is present by calling getrandom with an empty buffer and seeing if `ENOSYS` is returned. However, even with an empty buffer, this call will block unless we explicitly pass a flag. This can be seen in the source for `getrandom`: https://elixir.bootlin.com/linux/v5.1.8/source/drivers/char/random.c#L2043 This change adds a boolean parameter to `syscall_getrandom` to control the blocking behavior. We now don't block in initialization, but do block when actually reading random data.
getrandom
A Rust library for retrieving random data from (operating) system source. It is
assumed that system always provides high-quality cryptographically secure random
data, ideally backed by hardware entropy sources. This crate derives its name
from Linux's getrandom function, but is cross platform, roughly supporting
the same set of platforms as Rust's std lib.
This is a low-level API. Most users should prefer using high-level random-number
library like rand.
Usage
Add this to your Cargo.toml:
[dependencies]
getrandom = "0.1"
Then invoke the getrandom function:
fn get_random_buf() -> Result<[u8; 32], getrandom::Error> {
let mut buf = [0u8; 32];
getrandom::getrandom(&mut buf)?;
buf
}
Features
This library is no_std compatible, but uses std on most platforms.
The log library is supported as an optional dependency. If enabled, error
reporting will be improved on some platforms.
For WebAssembly (wasm32), WASI and Emscripten targets are supported directly; otherwise
one of the following features must be enabled:
Minimum Supported Rust Version
This crate requires Rust 1.32.0 or later.
License
The getrandom library is distributed under either of
at your option.