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std: Unsafe-wrap alloc code held in-common

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This commit is contained in:
Jubilee Young 2024-07-23 01:12:29 -07:00
parent cefe1dcef0
commit ed809e9b79
1 changed files with 11 additions and 8 deletions
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19
library/std/src/sys/pal/common/alloc.rs
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@ -1,3 +1,4 @@
#![forbid(unsafe_op_in_unsafe_fn)]
use crate::alloc::{GlobalAlloc, Layout, System};
use crate::cmp;
use crate::ptr;
@ -46,14 +47,16 @@ pub unsafe fn realloc_fallback(
old_layout: Layout,
new_size: usize,
) -> *mut u8 {
// Docs for GlobalAlloc::realloc require this to be valid:
let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align());
// SAFETY: Docs for GlobalAlloc::realloc require this to be valid
unsafe {
let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align());
let new_ptr = GlobalAlloc::alloc(alloc, new_layout);
if !new_ptr.is_null() {
let size = cmp::min(old_layout.size(), new_size);
ptr::copy_nonoverlapping(ptr, new_ptr, size);
GlobalAlloc::dealloc(alloc, ptr, old_layout);
let new_ptr = GlobalAlloc::alloc(alloc, new_layout);
if !new_ptr.is_null() {
let size = cmp::min(old_layout.size(), new_size);
ptr::copy_nonoverlapping(ptr, new_ptr, size);
GlobalAlloc::dealloc(alloc, ptr, old_layout);
}
new_ptr
}
new_ptr
}