#![allow(unstable_name_collisions)]
#![allow(dead_code)]
#![allow(deprecated)]
use core::cmp;
use core::fmt;
use core::mem;
use core::ptr::{self, NonNull};
use core::usize;
pub use core::alloc::{Layout, LayoutErr};
fn new_layout_err() -> LayoutErr {
Layout::from_size_align(1, 3).unwrap_err()
}
pub fn handle_alloc_error(layout: Layout) -> ! {
panic!("encountered allocation error: {:?}", layout)
}
pub trait UnstableLayoutMethods {
fn padding_needed_for(&self, align: usize) -> usize;
fn repeat(&self, n: usize) -> Result<(Layout, usize), LayoutErr>;
fn array<T>(n: usize) -> Result<Layout, LayoutErr>;
}
impl UnstableLayoutMethods for Layout {
fn padding_needed_for(&self, align: usize) -> usize {
let len = self.size();
let len_rounded_up = len.wrapping_add(align).wrapping_sub(1) & !align.wrapping_sub(1);
len_rounded_up.wrapping_sub(len)
}
fn repeat(&self, n: usize) -> Result<(Layout, usize), LayoutErr> {
let padded_size = self
.size()
.checked_add(self.padding_needed_for(self.align()))
.ok_or_else(new_layout_err)?;
let alloc_size = padded_size.checked_mul(n).ok_or_else(new_layout_err)?;
unsafe {
Ok((
Layout::from_size_align_unchecked(alloc_size, self.align()),
padded_size,
))
}
}
fn array<T>(n: usize) -> Result<Layout, LayoutErr> {
Layout::new::<T>().repeat(n).map(|(k, offs)| {
debug_assert!(offs == mem::size_of::<T>());
k
})
}
}
#[derive(Debug)]
pub struct Excess(pub NonNull<u8>, pub usize);
fn size_align<T>() -> (usize, usize) {
(mem::size_of::<T>(), mem::align_of::<T>())
}
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct AllocErr;
impl fmt::Display for AllocErr {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("memory allocation failed")
}
}
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct CannotReallocInPlace;
impl CannotReallocInPlace {
pub fn description(&self) -> &str {
"cannot reallocate allocator's memory in place"
}
}
impl fmt::Display for CannotReallocInPlace {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.description())
}
}
pub unsafe trait Alloc {
unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr>;
unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout);
#[inline]
fn usable_size(&self, layout: &Layout) -> (usize, usize) {
(layout.size(), layout.size())
}
unsafe fn realloc(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<NonNull<u8>, AllocErr> {
let old_size = layout.size();
if new_size >= old_size {
if let Ok(()) = self.grow_in_place(ptr, layout, new_size) {
return Ok(ptr);
}
} else if new_size < old_size {
if let Ok(()) = self.shrink_in_place(ptr, layout, new_size) {
return Ok(ptr);
}
}
let new_layout = Layout::from_size_align_unchecked(new_size, layout.align());
let result = self.alloc(new_layout);
if let Ok(new_ptr) = result {
ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_ptr(), cmp::min(old_size, new_size));
self.dealloc(ptr, layout);
}
result
}
unsafe fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
let size = layout.size();
let p = self.alloc(layout);
if let Ok(p) = p {
ptr::write_bytes(p.as_ptr(), 0, size);
}
p
}
unsafe fn alloc_excess(&mut self, layout: Layout) -> Result<Excess, AllocErr> {
let usable_size = self.usable_size(&layout);
self.alloc(layout).map(|p| Excess(p, usable_size.1))
}
unsafe fn realloc_excess(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<Excess, AllocErr> {
let new_layout = Layout::from_size_align_unchecked(new_size, layout.align());
let usable_size = self.usable_size(&new_layout);
self.realloc(ptr, layout, new_size)
.map(|p| Excess(p, usable_size.1))
}
unsafe fn grow_in_place(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<(), CannotReallocInPlace> {
let _ = ptr; debug_assert!(new_size >= layout.size());
let (_l, u) = self.usable_size(&layout);
if new_size <= u {
Ok(())
} else {
Err(CannotReallocInPlace)
}
}
unsafe fn shrink_in_place(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<(), CannotReallocInPlace> {
let _ = ptr; debug_assert!(new_size <= layout.size());
let (l, _u) = self.usable_size(&layout);
if l <= new_size {
Ok(())
} else {
Err(CannotReallocInPlace)
}
}
fn alloc_one<T>(&mut self) -> Result<NonNull<T>, AllocErr>
where
Self: Sized,
{
let k = Layout::new::<T>();
if k.size() > 0 {
unsafe { self.alloc(k).map(|p| p.cast()) }
} else {
Err(AllocErr)
}
}
unsafe fn dealloc_one<T>(&mut self, ptr: NonNull<T>)
where
Self: Sized,
{
let k = Layout::new::<T>();
if k.size() > 0 {
self.dealloc(ptr.cast(), k);
}
}
fn alloc_array<T>(&mut self, n: usize) -> Result<NonNull<T>, AllocErr>
where
Self: Sized,
{
match Layout::array::<T>(n) {
Ok(layout) if layout.size() > 0 => unsafe { self.alloc(layout).map(|p| p.cast()) },
_ => Err(AllocErr),
}
}
unsafe fn realloc_array<T>(
&mut self,
ptr: NonNull<T>,
n_old: usize,
n_new: usize,
) -> Result<NonNull<T>, AllocErr>
where
Self: Sized,
{
match (Layout::array::<T>(n_old), Layout::array::<T>(n_new)) {
(Ok(ref k_old), Ok(ref k_new)) if k_old.size() > 0 && k_new.size() > 0 => {
debug_assert!(k_old.align() == k_new.align());
self.realloc(ptr.cast(), k_old.clone(), k_new.size())
.map(NonNull::cast)
}
_ => Err(AllocErr),
}
}
unsafe fn dealloc_array<T>(&mut self, ptr: NonNull<T>, n: usize) -> Result<(), AllocErr>
where
Self: Sized,
{
match Layout::array::<T>(n) {
Ok(k) if k.size() > 0 => {
self.dealloc(ptr.cast(), k);
Ok(())
}
_ => Err(AllocErr),
}
}
}