// unsafe: see thread::Builder::spawn_unchecked for safety requirements

pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {

let p = Box::into_raw(Box::new(p));

let mut native: libc::pthread_t = mem::zeroed();

let mut attr: libc::pthread_attr_t = mem::zeroed();

assert_eq!(libc::pthread_attr_init(&mut attr), 0);

let mut native: libc::pthread_t = unsafe { mem::zeroed() };

let mut attr: libc::pthread_attr_t = unsafe { mem::zeroed() };

assert_eq!(unsafe { libc::pthread_attr_init(&mut attr) }, 0);

assert_eq!(

libc::pthread_attr_settee(

&mut attr,

libc::TEESMP_THREAD_ATTR_CA_INHERIT,

libc::TEESMP_THREAD_ATTR_TASK_ID_INHERIT,

libc::TEESMP_THREAD_ATTR_HAS_SHADOW,

),

unsafe {

libc::pthread_attr_settee(

&mut attr,

libc::TEESMP_THREAD_ATTR_CA_INHERIT,

libc::TEESMP_THREAD_ATTR_TASK_ID_INHERIT,

libc::TEESMP_THREAD_ATTR_HAS_SHADOW,

)

},

0,

);

let stack_size = cmp::max(stack, min_stack_size(&attr));

match libc::pthread_attr_setstacksize(&mut attr, stack_size) {

match unsafe { libc::pthread_attr_setstacksize(&mut attr, stack_size) } {

0 => {}

n => {

assert_eq!(n, libc::EINVAL);

let page_size = os::page_size();

let stack_size =

(stack_size + page_size - 1) & (-(page_size as isize - 1) as usize - 1);

assert_eq!(libc::pthread_attr_setstacksize(&mut attr, stack_size), 0);

assert_eq!(unsafe { libc::pthread_attr_setstacksize(&mut attr, stack_size) }, 0);

}

};

let ret = libc::pthread_create(&mut native, &attr, thread_start, p as *mut _);

// Note: if the thread creation fails and this assert fails, then p will

// be leaked. However, an alternative design could cause double-free

// which is clearly worse.

assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);

assert_eq!(unsafe { libc::pthread_attr_destroy(&mut attr) }, 0);

return if ret != 0 {

// The thread failed to start and as a result p was not consumed. Therefore, it is

// safe to reconstruct the box so that it gets deallocated.

drop(Box::from_raw(p));

drop(unsafe { Box::from_raw(p) });

Err(io::Error::from_raw_os_error(ret))

} else {

// The new thread will start running earliest after the next yield.