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Revert using HEAP static in Windows alloc

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This commit is contained in:
Chris Denton 2024-10-18 10:57:45 +00:00
parent db8043bb19
commit 64ec068ca1
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GPG Key ID: 713472F2F45627DE
1 changed files with 14 additions and 59 deletions
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73
library/std/src/sys/alloc/windows.rs
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@ -3,7 +3,6 @@
use crate::ffi::c_void;
use crate::mem::MaybeUninit;
use crate::ptr;
use crate::sync::atomic::{AtomicPtr, Ordering};
use crate::sys::c;
#[cfg(test)]
@ -81,45 +80,9 @@
// See https://docs.microsoft.com/windows/win32/api/heapapi/nf-heapapi-heapfree
windows_targets::link!("kernel32.dll" "system" fn HeapFree(hheap: c::HANDLE, dwflags: u32, lpmem: *const c_void) -> c::BOOL);
// Cached handle to the default heap of the current process.
// Either a non-null handle returned by `GetProcessHeap`, or null when not yet initialized or `GetProcessHeap` failed.
static HEAP: AtomicPtr<c_void> = AtomicPtr::new(ptr::null_mut());
// Get a handle to the default heap of the current process, or null if the operation fails.
// If this operation is successful, `HEAP` will be successfully initialized and contain
// a non-null handle returned by `GetProcessHeap`.
#[inline]
fn init_or_get_process_heap() -> c::HANDLE {
// `HEAP` has not yet been successfully initialized
let heap = unsafe { GetProcessHeap() };
if !heap.is_null() {
// SAFETY: No locking is needed because within the same process,
// successful calls to `GetProcessHeap` will always return the same value, even on different threads.
HEAP.store(heap, Ordering::Release);
// SAFETY: `HEAP` contains a non-null handle returned by `GetProcessHeap`
heap
} else {
// Could not get the current process heap.
ptr::null_mut()
}
}
/// This is outlined from `process_heap_alloc` so that `process_heap_alloc`
/// does not need any stack allocations.
#[inline(never)]
#[cold]
extern "C" fn process_heap_init_and_alloc(
_heap: MaybeUninit<c::HANDLE>, // We pass this argument to match the ABI of `HeapAlloc`
flags: u32,
bytes: usize,
) -> *mut c_void {
let heap = init_or_get_process_heap();
if core::intrinsics::unlikely(heap.is_null()) {
return ptr::null_mut();
}
// SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`.
unsafe { HeapAlloc(heap, flags, bytes) }
fn get_process_heap() -> *mut c_void {
// SAFETY: GetProcessHeap simply returns a valid handle or NULL so is always safe to call.
unsafe { GetProcessHeap() }
}
#[inline(never)]
@ -128,20 +91,12 @@ fn process_heap_alloc(
flags: u32,
bytes: usize,
) -> *mut c_void {
let heap = HEAP.load(Ordering::Relaxed);
if core::intrinsics::likely(!heap.is_null()) {
// SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`.
unsafe { HeapAlloc(heap, flags, bytes) }
} else {
process_heap_init_and_alloc(MaybeUninit::uninit(), flags, bytes)
let heap = get_process_heap();
if core::intrinsics::unlikely(heap.is_null()) {
return ptr::null_mut();
}
}
// Get a non-null handle to the default heap of the current process.
// SAFETY: `HEAP` must have been successfully initialized.
#[inline]
unsafe fn get_process_heap() -> c::HANDLE {
HEAP.load(Ordering::Acquire)
// SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`.
unsafe { HeapAlloc(heap, flags, bytes) }
}
// Header containing a pointer to the start of an allocated block.
@ -232,9 +187,9 @@ unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
}
};
// SAFETY: because `ptr` has been successfully allocated with this allocator,
// `HEAP` must have been successfully initialized.
let heap = unsafe { get_process_heap() };
// because `ptr` has been successfully allocated with this allocator,
// there must be a valid process heap.
let heap = get_process_heap();
// SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`,
// `block` is a pointer to the start of an allocated block.
@ -244,9 +199,9 @@ unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
#[inline]
unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
if layout.align() <= MIN_ALIGN {
// SAFETY: because `ptr` has been successfully allocated with this allocator,
// `HEAP` must have been successfully initialized.
let heap = unsafe { get_process_heap() };
// because `ptr` has been successfully allocated with this allocator,
// there must be a valid process heap.
let heap = get_process_heap();
// SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`,
// `ptr` is a pointer to the start of an allocated block.