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use std::fmt;
use std::io;
use std::mem;
use std::ptr;
use winapi::shared::ntdef::{HANDLE, NULL};
use winapi::um::minwinbase::*;
use winapi::um::synchapi::*;
/// A wrapper around `OVERLAPPED` to provide "rustic" accessors and
/// initializers.
pub struct Overlapped(OVERLAPPED);
impl fmt::Debug for Overlapped {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "OVERLAPPED")
}
}
unsafe impl Send for Overlapped {}
unsafe impl Sync for Overlapped {}
impl Overlapped {
/// Creates a new zeroed out instance of an overlapped I/O tracking state.
///
/// This is suitable for passing to methods which will then later get
/// notified via an I/O Completion Port.
pub fn zero() -> Overlapped {
Overlapped(unsafe { mem::zeroed() })
}
/// Creates a new `Overlapped` with an initialized non-null `hEvent`. The caller is
/// responsible for calling `CloseHandle` on the `hEvent` field of the returned
/// `Overlapped`. The event is created with `bManualReset` set to `FALSE`, meaning after a
/// single thread waits on the event, it will be reset.
pub fn initialize_with_autoreset_event() -> io::Result<Overlapped> {
let event = unsafe { CreateEventW(ptr::null_mut(), 0i32, 0i32, ptr::null()) };
if event == NULL {
return Err(io::Error::last_os_error());
}
let mut overlapped = Self::zero();
overlapped.set_event(event);
Ok(overlapped)
}
/// Creates a new `Overlapped` function pointer from the underlying
/// `OVERLAPPED`, wrapping in the "rusty" wrapper for working with
/// accessors.
///
/// # Unsafety
///
/// This function doesn't validate `ptr` nor the lifetime of the returned
/// pointer at all, it's recommended to use this method with extreme
/// caution.
pub unsafe fn from_raw<'a>(ptr: *mut OVERLAPPED) -> &'a mut Overlapped {
&mut *(ptr as *mut Overlapped)
}
/// Gain access to the raw underlying data
pub fn raw(&self) -> *mut OVERLAPPED {
&self.0 as *const _ as *mut _
}
/// Sets the offset inside this overlapped structure.
///
/// Note that for I/O operations in general this only has meaning for I/O
/// handles that are on a seeking device that supports the concept of an
/// offset.
pub fn set_offset(&mut self, offset: u64) {
let s = unsafe { self.0.u.s_mut() };
s.Offset = offset as u32;
s.OffsetHigh = (offset >> 32) as u32;
}
/// Reads the offset inside this overlapped structure.
pub fn offset(&self) -> u64 {
let s = unsafe { self.0.u.s() };
(s.Offset as u64) | ((s.OffsetHigh as u64) << 32)
}
/// Sets the `hEvent` field of this structure.
///
/// The event specified can be null.
pub fn set_event(&mut self, event: HANDLE) {
self.0.hEvent = event;
}
/// Reads the `hEvent` field of this structure, may return null.
pub fn event(&self) -> HANDLE {
self.0.hEvent
}
}