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// SPDX-License-Identifier: MIT
use core::alloc::{GlobalAlloc, Layout};
use core::ffi::c_void;
use core::ptr;
use cty::*;
extern "C" {
pub fn malloc(size: size_t) -> *mut c_void;
pub fn realloc_in_place(p: *mut c_void, size: size_t) -> *mut c_void;
pub fn free(p: *mut c_void);
pub fn posix_memalign(p: *mut *mut c_void, alignment: size_t, size: size_t) -> c_int;
}
pub struct DLMalloc;
unsafe impl GlobalAlloc for DLMalloc {
#[inline]
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
let mut ptr = ptr::null_mut();
let ret = unsafe {
posix_memalign(
&mut ptr,
layout.align().max(core::mem::size_of::<usize>()),
layout.size(),
)
};
if ret == 0 {
ptr as *mut u8
} else {
ptr::null_mut()
}
}
#[inline]
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
// Unfortunately, calloc doesn't make any alignment guarantees, so the memory
// has to be manually zeroed-out.
let ptr = unsafe { self.alloc(layout) };
if !ptr.is_null() {
unsafe { ptr::write_bytes(ptr, 0, layout.size()) };
}
ptr
}
#[inline]
unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
unsafe {
free(ptr as *mut c_void);
}
}
#[inline]
unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
// Unfortunately, realloc doesn't make any alignment guarantees, so the memory
// has to be manually allocated as aligned memory if it cannot be resized
// in-place.
let mut new_ptr = unsafe { realloc_in_place(ptr as *mut c_void, new_size) as *mut u8 };
// return early if in-place resize succeeded
if !new_ptr.is_null() {
return new_ptr;
}
// allocate new aligned storage with correct layout
new_ptr =
unsafe { self.alloc(Layout::from_size_align_unchecked(new_size, layout.align())) };
// return early if allocation failed
if new_ptr.is_null() {
return ptr::null_mut();
}
// copy over the data and deallocate the old storage
unsafe { ptr::copy(ptr, new_ptr, layout.size().min(new_size)) };
unsafe { self.dealloc(ptr, layout) };
new_ptr
}
}
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