#[repr(transparent)]pub struct HandleOrInvalid(_);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 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 concerns any value other than INVALID_HANDLE_VALUE to be valid, including NULL.
This is because APIs that use INVALID_HANDLE_VALUE as their sentry value may return NULL
under windows_subsystem = "windows" or other situations where I/O devices are detached.
If this holds a valid handle, it will close the handle on drop.
Trait Implementations
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 resource pointed to by handle must be either open and otherwise
unowned, null, or equal to INVALID_HANDLE_VALUE (-1). Note that not
all Windows APIs use INVALID_HANDLE_VALUE for errors; see here for
the full story.