HandleOrInvalid in std::os::windows::io - Rust (original) (raw)
Struct HandleOrInvalid
1.63.0 · Source
pub struct HandleOrInvalid(/* private fields */);Available on Windows only.
Expand description
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 usesrepr(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 anOwnedHandle using its TryFrom implementation; this conversion takes care of the check forINVALID_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.
1.63.0 · Source
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 beINVALID_HANDLE_VALUE (-1). Note that not all Windows APIs useINVALID_HANDLE_VALUE for errors; see here for the full story.