//! Implementation for Linux / Android with `/dev/urandom` fallback use crate::{ lazy::LazyBool, util_libc::{getrandom_syscall, last_os_error, sys_fill_exact}, {use_file, Error}, }; use core::mem::MaybeUninit; pub fn getrandom_inner(dest: &mut [MaybeUninit]) -> Result<(), Error> { // getrandom(2) was introduced in Linux 3.17 static HAS_GETRANDOM: LazyBool = LazyBool::new(); if HAS_GETRANDOM.unsync_init(is_getrandom_available) { sys_fill_exact(dest, getrandom_syscall) } else { use_file::getrandom_inner(dest) } } fn is_getrandom_available() -> bool { if getrandom_syscall(&mut []) < 0 { match last_os_error().raw_os_error() { Some(libc::ENOSYS) => false, // No kernel support // The fallback on EPERM is intentionally not done on Android since this workaround // seems to be needed only for specific Linux-based products that aren't based // on Android. See https://github.com/rust-random/getrandom/issues/229. #[cfg(target_os = "linux")] Some(libc::EPERM) => false, // Blocked by seccomp _ => true, } } else { true } }