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request at least ptr-size alignment from posix_memalign

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This commit is contained in:
Ralf Jung 2019-07-02 09:17:38 +02:00
parent 6ea4036cd2
commit 2bad604587
1 changed files with 11 additions and 1 deletions
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12
src/libstd/sys/unix/alloc.rs
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@ -1,11 +1,15 @@
use crate::ptr;
use crate::sys_common::alloc::{MIN_ALIGN, realloc_fallback};
use crate::alloc::{GlobalAlloc, Layout, System};
use crate::mem;
#[stable(feature = "alloc_system_type", since = "1.28.0")]
unsafe impl GlobalAlloc for System {
#[inline]
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
// jemalloc provides alignment less than MIN_ALIGN for small allocations.
// So only rely on MIN_ALIGN if size >= align.
// Also see <https://github.com/rust-lang/rust/issues/45955>.
if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
libc::malloc(layout.size()) as *mut u8
} else {
@ -21,6 +25,9 @@ unsafe impl GlobalAlloc for System {
#[inline]
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
// jemalloc provides alignment less than MIN_ALIGN for small allocations.
// So only rely on MIN_ALIGN if size >= align.
// Also see <https://github.com/rust-lang/rust/issues/45955>.
if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
libc::calloc(layout.size(), 1) as *mut u8
} else {
@ -80,7 +87,10 @@ unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
#[inline]
unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
let mut out = ptr::null_mut();
let ret = libc::posix_memalign(&mut out, layout.align(), layout.size());
// posix_memalign requires that the alignment be a multiple of `sizeof(void*)`.
// Since these are all powers of 2, we can just use max.
let align = layout.align().max(mem::size_of::<usize>());
let ret = libc::posix_memalign(&mut out, align, layout.size());
if ret != 0 {
ptr::null_mut()
} else {