1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
use crate::{get_stack_limit, set_stack_limit};
pub struct StackRestoreGuard {
new_stack: *mut u8,
stack_bytes: usize,
old_stack_limit: Option<usize>,
}
const ALIGNMENT: usize = 16;
impl StackRestoreGuard {
pub fn new(stack_bytes: usize) -> StackRestoreGuard {
// On these platforms we do not use stack guards. this is very unfortunate,
// but there is not much we can do about it without OS support.
// We simply allocate the requested size from the global allocator with a suitable
// alignment.
let stack_bytes = stack_bytes
.checked_add(ALIGNMENT - 1)
.expect("unreasonably large stack requested")
/ ALIGNMENT
* ALIGNMENT;
let layout = std::alloc::Layout::from_size_align(stack_bytes, ALIGNMENT).unwrap();
let ptr = unsafe { std::alloc::alloc(layout) };
assert!(!ptr.is_null(), "unable to allocate stack");
StackRestoreGuard {
new_stack: ptr,
stack_bytes,
old_stack_limit: get_stack_limit(),
}
}
pub fn stack_area(&self) -> (*mut u8, usize) {
(self.new_stack, self.stack_bytes)
}
}
impl Drop for StackRestoreGuard {
fn drop(&mut self) {
unsafe {
std::alloc::dealloc(
self.new_stack,
std::alloc::Layout::from_size_align_unchecked(self.stack_bytes, ALIGNMENT),
);
}
set_stack_limit(self.old_stack_limit);
}
}
|
