ret

}

unsafe fn get_stack_start_aligned() -> Option<*mut libc::c_void> {

let page_size = PAGE_SIZE.load(Ordering::Relaxed);

let stackptr = get_stack_start()?;

fn stack_start_aligned(page_size: usize) -> Option<*mut libc::c_void> {

let stackptr = unsafe { get_stack_start()? };

let stackaddr = stackptr.addr();

// Ensure stackaddr is page aligned! A parent process might

}

}

#[forbid(unsafe_op_in_unsafe_fn)]

unsafe fn install_main_guard_linux(page_size: usize) -> Option<Range<usize>> {

// Linux doesn't allocate the whole stack right away, and

// the kernel has its own stack-guard mechanism to fault

// Instead, we'll just note where we expect rlimit to start

// faulting, so our handler can report "stack overflow", and

// trust that the kernel's own stack guard will work.

let stackptr = get_stack_start_aligned()?;

let stackptr = stack_start_aligned(page_size)?;

let stackaddr = stackptr.addr();

Some(stackaddr - page_size..stackaddr)

}

#[forbid(unsafe_op_in_unsafe_fn)]

unsafe fn install_main_guard_linux_musl(_page_size: usize) -> Option<Range<usize>> {

// For the main thread, the musl's pthread_attr_getstack

// returns the current stack size, rather than maximum size

// at the bottom. If we try to remap the bottom of the stack

// ourselves, FreeBSD's guard page moves upwards. So we'll just use

// the builtin guard page.

let stackptr = get_stack_start_aligned()?;

let stackptr = stack_start_aligned(page_size)?;

let guardaddr = stackptr.addr();

// Technically the number of guard pages is tunable and controlled

// by the security.bsd.stack_guard_page sysctl.

Some(guardaddr..guardaddr + pages * page_size)

}

#[forbid(unsafe_op_in_unsafe_fn)]

unsafe fn install_main_guard_bsds(page_size: usize) -> Option<Range<usize>> {

// OpenBSD stack already includes a guard page, and stack is

// immutable.

// We'll just note where we expect rlimit to start

// faulting, so our handler can report "stack overflow", and

// trust that the kernel's own stack guard will work.

let stackptr = get_stack_start_aligned()?;

let stackptr = stack_start_aligned(page_size)?;

let stackaddr = stackptr.addr();

Some(stackaddr - page_size..stackaddr)

}

// than the initial mmap() used, so we mmap() here with

// read/write permissions and only then mprotect() it to

// no permissions at all. See issue #50313.

let stackptr = get_stack_start_aligned()?;

let stackptr = stack_start_aligned(page_size)?;

let result = mmap64(

stackptr,

page_size,