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//! Data type definitions
//!
//! This module defines the basic data types that are used throughout uefi-rs
use core::{ffi::c_void, ptr::NonNull};
/// Opaque handle to an UEFI entity (protocol, image...), guaranteed to be non-null.
///
/// If you need to have a nullable handle (for a custom UEFI FFI for example) use `Option<Handle>`.
#[derive(Clone, Copy, Debug)]
#[repr(transparent)]
pub struct Handle(NonNull<c_void>);
impl Handle {
/// Creates a new [`Handle`] from a raw address. The address might
/// come from the Multiboot2 information structure or something similar.
///
/// # Example
/// ```no_run
/// use core::ffi::c_void;
/// use uefi::Handle;
///
/// let image_handle_addr = 0xdeadbeef as *mut c_void;
///
/// let uefi_image_handle = unsafe {
/// Handle::from_ptr(image_handle_addr).expect("Pointer must not be null!")
/// };
/// ```
///
/// # Safety
/// This function is unsafe because the caller must be sure that the pointer
/// is valid. Otherwise, further operations on the object might result in
/// undefined behaviour, even if the methods aren't marked as unsafe.
pub unsafe fn from_ptr(ptr: *mut c_void) -> Option<Self> {
// shorthand for "|ptr| Self(ptr)"
NonNull::new(ptr).map(Self)
}
}
/// Handle to an event structure
#[repr(transparent)]
pub struct Event(*mut c_void);
impl Event {
/// Clone this `Event`
///
/// # Safety
/// When an event is closed by calling `BootServices::close_event`, that event and ALL references
/// to it are invalidated and the underlying memory is freed by firmware. The caller must ensure
/// that any clones of a closed `Event` are never used again.
#[must_use]
pub unsafe fn unsafe_clone(&self) -> Self {
Self(self.0)
}
}
/// Trait for querying the alignment of a struct.
///
/// For a statically-sized type the alignment can be retrieved with
/// [`core::mem::align_of`]. For a dynamically-sized type (DST),
/// [`core::mem::align_of_val`] provides the alignment given a reference. But in
/// some cases it's helpful to know the alignment of a DST prior to having a
/// value, meaning there's no reference to pass to `align_of_val`. For example,
/// when using an API that creates a value using a `[u8]` buffer, the alignment
/// of the buffer must be checked. The `Align` trait makes that possible by
/// allowing the appropriate alignment to be manually specified.
pub trait Align {
/// Required memory alignment for this type
fn alignment() -> usize;
/// Calculate the offset from `val` necessary to make it aligned,
/// rounding up. For example, if `val` is 1 and the alignment is 8,
/// this will return 7. Returns 0 if `val == 0`.
fn offset_up_to_alignment(val: usize) -> usize {
assert!(Self::alignment() != 0);
let r = val % Self::alignment();
if r == 0 {
0
} else {
Self::alignment() - r
}
}
/// Round `val` up so that it is aligned.
fn round_up_to_alignment(val: usize) -> usize {
val + Self::offset_up_to_alignment(val)
}
/// Get a subslice of `buf` where the address of the first element
/// is aligned. Returns `None` if no element of the buffer is
/// aligned.
fn align_buf(buf: &mut [u8]) -> Option<&mut [u8]> {
let addr = buf.as_ptr() as usize;
let offset = Self::offset_up_to_alignment(addr);
buf.get_mut(offset..)
}
/// Assert that some storage is correctly aligned for this type
fn assert_aligned(storage: &mut [u8]) {
if !storage.is_empty() {
assert_eq!(
(storage.as_ptr() as usize) % Self::alignment(),
0,
"The provided storage is not correctly aligned for this type"
)
}
}
}
mod guid;
pub use self::guid::Guid;
pub use self::guid::{unsafe_guid, Identify};
pub mod chars;
pub use self::chars::{Char16, Char8};
#[macro_use]
mod enums;
mod strs;
pub use self::strs::{CStr16, CStr8, FromSliceWithNulError, FromStrWithBufError};
#[cfg(feature = "exts")]
mod owned_strs;
#[cfg(feature = "exts")]
pub use self::owned_strs::{CString16, FromStrError};
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_alignment() {
struct X {}
impl Align for X {
fn alignment() -> usize {
4
}
}
assert_eq!(X::offset_up_to_alignment(0), 0);
assert_eq!(X::offset_up_to_alignment(1), 3);
assert_eq!(X::offset_up_to_alignment(2), 2);
assert_eq!(X::offset_up_to_alignment(3), 1);
assert_eq!(X::offset_up_to_alignment(4), 0);
assert_eq!(X::offset_up_to_alignment(5), 3);
assert_eq!(X::offset_up_to_alignment(6), 2);
assert_eq!(X::offset_up_to_alignment(7), 1);
assert_eq!(X::offset_up_to_alignment(8), 0);
assert_eq!(X::round_up_to_alignment(0), 0);
assert_eq!(X::round_up_to_alignment(1), 4);
assert_eq!(X::round_up_to_alignment(2), 4);
assert_eq!(X::round_up_to_alignment(3), 4);
assert_eq!(X::round_up_to_alignment(4), 4);
assert_eq!(X::round_up_to_alignment(5), 8);
assert_eq!(X::round_up_to_alignment(6), 8);
assert_eq!(X::round_up_to_alignment(7), 8);
assert_eq!(X::round_up_to_alignment(8), 8);
// Get an intentionally mis-aligned buffer.
let mut buffer = [0u8; 16];
let mut buffer = &mut buffer[..];
if (buffer.as_ptr() as usize) % X::alignment() == 0 {
buffer = &mut buffer[1..];
}
let buffer = X::align_buf(buffer).unwrap();
X::assert_aligned(buffer);
}
}