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// Copyright 2023 The Fuchsia Authors
//
// Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
// This file may not be copied, modified, or distributed except according to
// those terms.
// See comment in `include.rs` for why we disable the prelude.
#![no_implicit_prelude]
#![allow(warnings)]
include!("include.rs");
// A struct is `imp::TryFromBytes` if:
// - any of its fields are `imp::TryFromBytes`
#[derive(imp::Immutable, imp::TryFromBytes)]
union One {
a: u8,
}
util_assert_impl_all!(One: imp::TryFromBytes);
#[test]
fn one() {
// FIXME(#5): Use `try_transmute` in this test once it's available.
let candidate = ::zerocopy::Ptr::from_ref(&One { a: 42 });
let candidate = candidate.forget_aligned();
// SAFETY: `&One` consists entirely of initialized bytes.
let candidate = unsafe { candidate.assume_initialized() };
let is_bit_valid = <One as imp::TryFromBytes>::is_bit_valid(candidate);
assert!(is_bit_valid);
}
#[derive(imp::Immutable, imp::TryFromBytes)]
#[repr(C)]
union Two {
a: bool,
b: bool,
}
util_assert_impl_all!(Two: imp::TryFromBytes);
#[test]
fn two() {
// FIXME(#5): Use `try_transmute` in this test once it's available.
let candidate_a = ::zerocopy::Ptr::from_ref(&Two { a: false });
let candidate_a = candidate_a.forget_aligned();
// SAFETY: `&Two` consists entirely of initialized bytes.
let candidate_a = unsafe { candidate_a.assume_initialized() };
let is_bit_valid = <Two as imp::TryFromBytes>::is_bit_valid(candidate_a);
assert!(is_bit_valid);
let candidate_b = ::zerocopy::Ptr::from_ref(&Two { b: true });
let candidate_b = candidate_b.forget_aligned();
// SAFETY: `&Two` consists entirely of initialized bytes.
let candidate_b = unsafe { candidate_b.assume_initialized() };
let is_bit_valid = <Two as imp::TryFromBytes>::is_bit_valid(candidate_b);
assert!(is_bit_valid);
}
#[test]
fn two_bad() {
// FIXME(#5): Use `try_transmute` in this test once it's available.
let candidate = ::zerocopy::Ptr::from_ref(&[2u8][..]);
let candidate = candidate.forget_aligned();
// SAFETY: `&[u8]` consists entirely of initialized bytes.
let candidate = unsafe { candidate.assume_initialized() };
// SAFETY:
// - The cast preserves address and size. As a result, the cast will address
// the same bytes as `c`.
// - The cast preserves provenance.
// - Neither the input nor output types contain any `UnsafeCell`s.
let candidate = unsafe { candidate.cast_unsized_unchecked(|p| p.cast::<Two>()) };
// SAFETY: `candidate`'s referent is as-initialized as `Two`.
let candidate = unsafe { candidate.assume_initialized() };
let is_bit_valid = <Two as imp::TryFromBytes>::is_bit_valid(candidate);
assert!(!is_bit_valid);
}
#[derive(imp::Immutable, imp::TryFromBytes)]
#[repr(C)]
union BoolAndZst {
a: bool,
b: (),
}
#[test]
fn bool_and_zst() {
// FIXME(#5): Use `try_transmute` in this test once it's available.
let candidate = ::zerocopy::Ptr::from_ref(&[2u8][..]);
let candidate = candidate.forget_aligned();
// SAFETY: `&[u8]` consists entirely of initialized bytes.
let candidate = unsafe { candidate.assume_initialized() };
// SAFETY:
// - The cast preserves address and size. As a result, the cast will address
// the same bytes as `c`.
// - The cast preserves provenance.
// - Neither the input nor output types contain any `UnsafeCell`s.
let candidate = unsafe { candidate.cast_unsized_unchecked(|p| p.cast::<BoolAndZst>()) };
// SAFETY: `candidate`'s referent is fully initialized.
let candidate = unsafe { candidate.assume_initialized() };
let is_bit_valid = <BoolAndZst as imp::TryFromBytes>::is_bit_valid(candidate);
assert!(is_bit_valid);
}
#[derive(imp::FromBytes)]
#[repr(C)]
union MaybeFromBytes<T: imp::Copy> {
t: T,
}
#[test]
fn test_maybe_from_bytes() {
// When deriving `FromBytes` on a type with no generic parameters, we emit a
// trivial `is_bit_valid` impl that always returns true. This test confirms
// that we *don't* spuriously do that when generic parameters are present.
let candidate = ::zerocopy::Ptr::from_ref(&[2u8][..]);
let candidate = candidate.bikeshed_recall_initialized_from_bytes();
// SAFETY:
// - The cast preserves address and size. As a result, the cast will address
// the same bytes as `c`.
// - The cast preserves provenance.
// - Neither the input nor output types contain any `UnsafeCell`s.
let candidate =
unsafe { candidate.cast_unsized_unchecked(|p| p.cast::<MaybeFromBytes<bool>>()) };
// SAFETY: `[u8]` consists entirely of initialized bytes.
let candidate = unsafe { candidate.assume_initialized() };
let is_bit_valid = <MaybeFromBytes<bool> as imp::TryFromBytes>::is_bit_valid(candidate);
imp::assert!(!is_bit_valid);
}
#[derive(imp::Immutable, imp::TryFromBytes)]
#[repr(C)]
union TypeParams<'a, T: imp::Copy, I: imp::Iterator>
where
I::Item: imp::Copy,
{
a: I::Item,
b: u8,
c: imp::PhantomData<&'a [u8]>,
d: imp::PhantomData<&'static str>,
e: imp::PhantomData<imp::String>,
f: T,
}
util_assert_impl_all!(TypeParams<'static, (), imp::IntoIter<()>>: imp::TryFromBytes);
util_assert_impl_all!(TypeParams<'static, util::AU16, imp::IntoIter<()>>: imp::TryFromBytes);
util_assert_impl_all!(TypeParams<'static, [util::AU16; 2], imp::IntoIter<()>>: imp::TryFromBytes);
// Deriving `imp::TryFromBytes` should work if the union has bounded parameters.
#[derive(imp::Immutable, imp::TryFromBytes)]
#[repr(C)]
union WithParams<'a: 'b, 'b: 'a, T: 'a + 'b + imp::TryFromBytes, const N: usize>
where
'a: 'b,
'b: 'a,
T: 'a + 'b + imp::TryFromBytes + imp::Copy,
{
a: imp::PhantomData<&'a &'b ()>,
b: T,
}
util_assert_impl_all!(WithParams<'static, 'static, u8, 42>: imp::TryFromBytes);
#[derive(Clone, Copy, imp::TryFromBytes, imp::Immutable)]
struct A;
#[derive(imp::TryFromBytes)]
union B {
a: A,
}
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