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Struct HandleOrInvalid 

pub struct HandleOrInvalid(/* private fields */);
Available on Windows only.

FFI type for handles in return values or out parameters, where INVALID_HANDLE_VALUE is used as a sentry value to indicate errors, such as in the return value of CreateFileW. This uses repr(transparent) and has the representation of a host handle, so that it can be used in such FFI declarations.

The only thing you can usefully do with a HandleOrInvalid is to convert it into an OwnedHandle using its TryFrom implementation; this conversion takes care of the check for INVALID_HANDLE_VALUE. This ensures that such FFI calls cannot start using the handle without checking for INVALID_HANDLE_VALUE first.

This type may hold any handle value that OwnedHandle may hold, except that when it holds -1, that value is interpreted to mean INVALID_HANDLE_VALUE.

If holds a handle other than INVALID_HANDLE_VALUE, it will close the handle on drop.

Implementations

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impl HandleOrInvalid
1.63.0Source
pub unsafe fn from_raw_handle(handle: RawHandle) -> Self

Constructs a new instance of Self from the given RawHandle returned from a Windows API that uses INVALID_HANDLE_VALUE to indicate failure, such as CreateFileW.

Use HandleOrNull instead of HandleOrInvalid for APIs that use null to indicate failure.

Safety

The passed handle value must either satisfy the safety requirements of FromRawHandle::from_raw_handle, or be INVALID_HANDLE_VALUE (-1). Note that not all Windows APIs use INVALID_HANDLE_VALUE for errors; see here for the full story.

Trait Implementations

1.63.0Source
impl Debug for HandleOrInvalid
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fn fmt(&self, f: &mut Formatter<'_>) -> Result
Formats the value using the given formatter. Read more
1.63.0Source
impl Drop for HandleOrInvalid
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fn drop(&mut self)
Executes the destructor for this type. Read more
1.63.0Source
impl TryFrom<HandleOrInvalid> for OwnedHandle
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type Error = InvalidHandleError
The type returned in the event of a conversion error.
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fn try_from(
    handle_or_invalid: HandleOrInvalid,
) -> Result<Self, InvalidHandleError>
Performs the conversion.
1.63.0Source
impl Send for HandleOrInvalid
1.63.0Source
impl Sync for HandleOrInvalid

Auto Trait Implementations

impl Freeze for HandleOrInvalid
impl RefUnwindSafe for HandleOrInvalid
impl Unpin for HandleOrInvalid
impl UnwindSafe for HandleOrInvalid

Blanket Implementations

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impl<T> Any for Twhere
    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 Twhere
    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 Twhere
    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> 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 Twhere
    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, U> TryFrom<U> for Twhere
    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 Twhere
    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.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/os/windows/io/struct.HandleOrInvalid.html