variablelength.rs

/// Never create or use this struct directly.
#[repr(C)]
pub struct RenameInfoW {
	_flags: u32,
	_root_dir: *const std::ffi::c_void,
	_name_length: u32,
	_name: [u16; 1],
}
impl RenameInfoW {
	const FLAGS_OFFSET: usize = 0;
	const DIR_OFFSET: usize = align::<usize>(Self::FLAGS_OFFSET + size_of::<u32>());
	const LENGTH_OFFSET: usize = align::<u32>(Self::DIR_OFFSET + size_of::<usize>());
	const NAME_OFFSET: usize = align::<u16>(Self::LENGTH_OFFSET + size_of::<u32>());

	pub unsafe fn flags(ptr: *mut u8) -> *mut RenameOptions {
		ptr.add(Self::FLAGS_OFFSET) as *mut _
	}
	pub unsafe fn root_dir(ptr: *mut u8) -> *mut *const std::ffi::c_void {
		ptr.add(Self::DIR_OFFSET) as *mut _
	}
	pub unsafe fn name_length(ptr: *mut u8) -> *mut u32 {
		ptr.add(Self::LENGTH_OFFSET) as *mut _
	}
	pub unsafe fn name(ptr: *mut u8) -> *mut u16 {
		ptr.add(Self::NAME_OFFSET) as *mut _
	}
}

/// Align `n` up to the alignment of `T`.
const fn align<T>(n: usize) -> usize {
	round_up_pow2_unchecked(n, align_of::<T>())
}
/// Rounds `n` up to nearest multiple of `pow2`.
///
/// * `pow2` must be a power of two and not zero.
/// * `n` must be less than `usize::MAX - pow2 - 1`.
const fn round_up_pow2_unchecked(n: usize, pow2: usize) -> usize {
	let round = pow2.wrapping_sub(1);
	n.wrapping_add(round) & !round
}