24 lines
1.1 KiB
Rust
24 lines
1.1 KiB
Rust
//! Implementation for iOS, tvOS, and watchOS where `getentropy` is unavailable.
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use crate::Error;
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use core::{ffi::c_void, mem::MaybeUninit};
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// libsystem contains the libc of Darwin, and every binary ends up linked against it either way. This
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// makes it a more lightweight choice compared to `Security.framework`.
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extern "C" {
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// This RNG uses a thread-local CSPRNG to provide data, which is seeded by the operating system's root CSPRNG.
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// Its the best option after `getentropy` on modern Darwin-based platforms that also avoids the
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// high startup costs and linking of Security.framework.
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//
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// While its just an implementation detail, `Security.framework` just calls into this anyway.
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fn CCRandomGenerateBytes(bytes: *mut c_void, size: usize) -> i32;
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}
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pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
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let ret = unsafe { CCRandomGenerateBytes(dest.as_mut_ptr() as *mut c_void, dest.len()) };
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// kCCSuccess (from CommonCryptoError.h) is always zero.
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if ret != 0 {
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Err(Error::IOS_SEC_RANDOM)
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} else {
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Ok(())
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}
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}
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