handle.rs.html -- source
Description: Source to the Rust file `src\libstd\sys\windows\handle.rs`.
Keywords: rust, rustlang, rust-lang

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    #![unstable(issue = "none", feature = "windows_handle")]

    use crate::cmp;
    use crate::io::{self, ErrorKind, IoSlice, IoSliceMut, Read};
    use crate::mem;
    use crate::ops::Deref;
    use crate::ptr;
    use crate::sys::c;
    use crate::sys::cvt;

    /// An owned container for `HANDLE` object, closing them on Drop.
    ///
    /// All methods are inherited through a `Deref` impl to `RawHandle`
    pub struct Handle(RawHandle);

    /// A wrapper type for `HANDLE` objects to give them proper Send/Sync inference
    /// as well as Rust-y methods.
    ///
    /// This does **not** drop the handle when it goes out of scope, use `Handle`
    /// instead for that.
    #[derive(Copy, Clone)]
    pub struct RawHandle(c::HANDLE);

    unsafe impl Send for RawHandle {}
    unsafe impl Sync for RawHandle {}

    impl Handle {
        pub fn new(handle: c::HANDLE) -> Handle {
            Handle(RawHandle::new(handle))
        }

        pub fn new_event(manual: bool, init: bool) -> io::Result<Handle> {
            unsafe {
                let event =
                    c::CreateEventW(ptr::null_mut(), manual as c::BOOL, init as c::BOOL, ptr::null());
                if event.is_null() { Err(io::Error::last_os_error()) } else { Ok(Handle::new(event)) }
            }
        }

        pub fn into_raw(self) -> c::HANDLE {
            let ret = self.raw();
            mem::forget(self);
            ret
        }
    }

    impl Deref for Handle {
        type Target = RawHandle;
        fn deref(&self) -> &RawHandle {
            &self.0
        }
    }

    impl Drop for Handle {
        fn drop(&mut self) {
            unsafe {
                let _ = c::CloseHandle(self.raw());
            }
        }
    }

    impl RawHandle {
        pub fn new(handle: c::HANDLE) -> RawHandle {
            RawHandle(handle)
        }

        pub fn raw(&self) -> c::HANDLE {
            self.0
        }

        pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
            let mut read = 0;
            let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
            let res = cvt(unsafe {
                c::ReadFile(self.0, buf.as_mut_ptr() as c::LPVOID, len, &mut read, ptr::null_mut())
            });

            match res {
                Ok(_) => Ok(read as usize),

                // The special treatment of BrokenPipe is to deal with Windows
                // pipe semantics, which yields this error when *reading* from
                // a pipe after the other end has closed; we interpret that as
                // EOF on the pipe.
                Err(ref e) if e.kind() == ErrorKind::BrokenPipe => Ok(0),

                Err(e) => Err(e),
            }
        }

        pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
            crate::io::default_read_vectored(|buf| self.read(buf), bufs)
        }

        #[inline]
        pub fn is_read_vectored(&self) -> bool {
            false
        }

        pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
            let mut read = 0;
            let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
            let res = unsafe {
                let mut overlapped: c::OVERLAPPED = mem::zeroed();
                overlapped.Offset = offset as u32;
                overlapped.OffsetHigh = (offset >> 32) as u32;
                cvt(c::ReadFile(self.0, buf.as_mut_ptr() as c::LPVOID, len, &mut read, &mut overlapped))
            };
            match res {
                Ok(_) => Ok(read as usize),
                Err(ref e) if e.raw_os_error() == Some(c::ERROR_HANDLE_EOF as i32) => Ok(0),
                Err(e) => Err(e),
            }
        }

        pub unsafe fn read_overlapped(
            &self,
            buf: &mut [u8],
            overlapped: *mut c::OVERLAPPED,
        ) -> io::Result<Option<usize>> {
            let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
            let mut amt = 0;
            let res = cvt(c::ReadFile(self.0, buf.as_ptr() as c::LPVOID, len, &mut amt, overlapped));
            match res {
                Ok(_) => Ok(Some(amt as usize)),
                Err(e) => {
                    if e.raw_os_error() == Some(c::ERROR_IO_PENDING as i32) {
                        Ok(None)
                    } else if e.raw_os_error() == Some(c::ERROR_BROKEN_PIPE as i32) {
                        Ok(Some(0))
                    } else {
                        Err(e)
                    }
                }
            }
        }

        pub fn overlapped_result(
            &self,
            overlapped: *mut c::OVERLAPPED,
            wait: bool,
        ) -> io::Result<usize> {
            unsafe {
                let mut bytes = 0;
                let wait = if wait { c::TRUE } else { c::FALSE };
                let res = cvt(c::GetOverlappedResult(self.raw(), overlapped, &mut bytes, wait));
                match res {
                    Ok(_) => Ok(bytes as usize),
                    Err(e) => {
                        if e.raw_os_error() == Some(c::ERROR_HANDLE_EOF as i32)
                            || e.raw_os_error() == Some(c::ERROR_BROKEN_PIPE as i32)
                        {
                            Ok(0)
                        } else {
                            Err(e)
                        }
                    }
                }
            }
        }

        pub fn cancel_io(&self) -> io::Result<()> {
            unsafe { cvt(c::CancelIo(self.raw())).map(drop) }
        }

        pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
            let mut amt = 0;
            let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
            cvt(unsafe {
                c::WriteFile(self.0, buf.as_ptr() as c::LPVOID, len, &mut amt, ptr::null_mut())
            })?;
            Ok(amt as usize)
        }

        pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
            crate::io::default_write_vectored(|buf| self.write(buf), bufs)
        }

        #[inline]
        pub fn is_write_vectored(&self) -> bool {
            false
        }

        pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
            let mut written = 0;
            let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
            unsafe {
                let mut overlapped: c::OVERLAPPED = mem::zeroed();
                overlapped.Offset = offset as u32;
                overlapped.OffsetHigh = (offset >> 32) as u32;
                cvt(c::WriteFile(
                    self.0,
                    buf.as_ptr() as c::LPVOID,
                    len,
                    &mut written,
                    &mut overlapped,
                ))?;
            }
            Ok(written as usize)
        }

        pub fn duplicate(
            &self,
            access: c::DWORD,
            inherit: bool,
            options: c::DWORD,
        ) -> io::Result<Handle> {
            let mut ret = 0 as c::HANDLE;
            cvt(unsafe {
                let cur_proc = c::GetCurrentProcess();
                c::DuplicateHandle(
                    cur_proc,
                    self.0,
                    cur_proc,
                    &mut ret,
                    access,
                    inherit as c::BOOL,
                    options,
                )
            })?;
            Ok(Handle::new(ret))
        }
    }

    impl<'a> Read for &'a RawHandle {
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            (**self).read(buf)
        }

        fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
            (**self).read_vectored(bufs)
        }
    }