pub struct HandleOrInvalid(/* private fields */);
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 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§
source§impl HandleOrInvalid
impl HandleOrInvalid
sourcepub unsafe fn from_raw_handle(handle: RawHandle) -> Self
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.