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## EventFd

# Struct EventFd

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    struct EventFd {
        counter: Cell<u64>,
        is_nonblock: bool,
        clock: RefCell<VClock>,
        blocked_read_tid: RefCell<Vec<ThreadId>>,
        blocked_write_tid: RefCell<Vec<ThreadId>>,
    }

Expand description

A kind of file descriptor created by `eventfd`. The `Event` type isn’t currently written to by `eventfd`. The interface is meant to keep track of objects associated with a file descriptor. For more information see the man page below:

https://man.netbsd.org/eventfd.2

## Fields§

§`counter: Cell<u64>`

The object contains an unsigned 64-bit integer (uint64_t) counter that is maintained by the kernel. This counter is initialized with the value specified in the argument initval.

§`is_nonblock: bool`§`clock: RefCell<VClock>`§`blocked_read_tid: RefCell<Vec<ThreadId>>`

A list of thread ids blocked on eventfd::read.

§`blocked_write_tid: RefCell<Vec<ThreadId>>`

A list of thread ids blocked on eventfd::write.

## Trait Implementations§

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### impl Debug for EventFd

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl FileDescription for EventFd

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#### fn read<'tcx>( self: FileDescriptionRef<Self>, _communicate_allowed: bool, ptr: Pointer, len: usize, ecx: &mut MiriInterpCx<'tcx>, finish: DynMachineCallback<'tcx, Result<usize, IoError>>, ) -> InterpResult<'tcx>

Read the counter in the buffer and return the counter if succeeded.

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#### fn write<'tcx>( self: FileDescriptionRef<Self>, _communicate_allowed: bool, ptr: Pointer, len: usize, ecx: &mut MiriInterpCx<'tcx>, finish: DynMachineCallback<'tcx, Result<usize, IoError>>, ) -> InterpResult<'tcx>

A write call adds the 8-byte integer value supplied in its buffer (in native endianness) to the counter. The maximum value that may be stored in the counter is the largest unsigned 64-bit value minus 1 (i.e., 0xfffffffffffffffe). If the addition would cause the counter’s value to exceed the maximum, then the write either blocks until a read is performed on the file descriptor, or fails with the error EAGAIN if the file descriptor has been made nonblocking.

A write fails with the error EINVAL if the size of the supplied buffer is less than 8 bytes, or if an attempt is made to write the value 0xffffffffffffffff.

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#### fn name(&self) -> &'static str

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#### fn metadata<'tcx>( &self, ) -> InterpResult<'tcx, Either<Result<Metadata>, &'static str>>

Returns the metadata for this FD, if available. This is either host metadata, or a non-file-backed-FD type. The latter is for new represented as a string storing a `libc` name so we only support that kind of metadata on Unix targets.
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#### fn destroy<'tcx>( self, _self_id: FdId, _communicate_allowed: bool, _ecx: &mut MiriInterpCx<'tcx>, ) -> InterpResult<'tcx, Result<()>>

Destroys the file description. Only called when the last duplicate file descriptor is closed. Read more
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#### fn as_unix<'tcx>(&self, _ecx: &MiriInterpCx<'tcx>) -> &dyn UnixFileDescription

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#### fn short_fd_operations(&self) -> bool

Determines whether this FD non-deterministically has its reads and writes shortened.
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#### fn seek<'tcx>( &self, _communicate_allowed: bool, _offset: SeekFrom, ) -> InterpResult<'tcx, Result<u64>>

Seeks to the given offset (which can be relative to the beginning, end, or current position). Returns the new position from the start of the stream.
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#### fn is_tty(&self, _communicate_allowed: bool) -> bool

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#### fn get_flags<'tcx>( &self, _ecx: &mut MiriInterpCx<'tcx>, ) -> InterpResult<'tcx, Scalar>

Implementation of fcntl(F_GETFL) for this FD.
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#### fn set_flags<'tcx>( &self, _flag: i32, _ecx: &mut MiriInterpCx<'tcx>, ) -> InterpResult<'tcx, Scalar>

Implementation of fcntl(F_SETFL) for this FD.
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### impl UnixFileDescription for EventFd

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#### fn epoll_active_events<'tcx>(&self) -> InterpResult<'tcx, EpollEvents>

Return which epoll events are currently active.
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#### fn pread<'tcx>( &self, _communicate_allowed: bool, _offset: u64, _ptr: Pointer, _len: usize, _ecx: &mut MiriInterpCx<'tcx>, _finish: DynMachineCallback<'tcx, Result<usize, IoError>>, ) -> InterpResult<'tcx>

Reads as much as possible into the given buffer `ptr` from a given offset. `len` indicates how many bytes we should try to read. `dest` is where the return value should be stored: number of bytes read, or `-1` in case of error.
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#### fn pwrite<'tcx>( &self, _communicate_allowed: bool, _ptr: Pointer, _len: usize, _offset: u64, _ecx: &mut MiriInterpCx<'tcx>, _finish: DynMachineCallback<'tcx, Result<usize, IoError>>, ) -> InterpResult<'tcx>

Writes as much as possible from the given buffer `ptr` starting at a given offset. `ptr` is the pointer to the user supplied read buffer. `len` indicates how many bytes we should try to write. `dest` is where the return value should be stored: number of bytes written, or `-1` in case of error.
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#### fn flock<'tcx>( &self, _communicate_allowed: bool, _op: FlockOp, ) -> InterpResult<'tcx, Result<()>>

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#### fn ioctl<'tcx>( &self, _op: Scalar, _arg: Option<&OpTy<'tcx>>, _ecx: &mut MiriInterpCx<'tcx>, ) -> InterpResult<'tcx, i32>

Modifies device parameters. `op` is the device-dependent operation code. It’s either a `c_long` or `c_int`, depending on the target and whether it uses glibc or musl. `arg` is the optional third argument which exists depending on the operation code. It’s either an integer or a pointer.

## Auto Trait Implementations§

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### impl !Freeze for EventFd

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### impl !RefUnwindSafe for EventFd

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### impl Send for EventFd

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### impl !Sync for EventFd

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### impl Unpin for EventFd

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### impl UnsafeUnpin for EventFd

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### impl UnwindSafe for EventFd

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> FileDescriptionExt for T
where T: FileDescription + 'static,

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#### fn into_rc_any(self: FileDescriptionRef<T>) -> Rc<dyn Any>

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#### fn close_ref<'tcx>( self: FileDescriptionRef<T>, communicate_allowed: bool, ecx: &mut InterpCx<'tcx, MiriMachine<'tcx>>, ) -> InterpResult<'tcx, Result<(), Error>>

We wrap the regular `close` function generically, so both handle `Rc::into_inner` and epoll interest management.
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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#### fn vzip(self) -> V

## Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain `repr(...)` attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 152 bytes