Struct std::os::windows::io::HandleOrInvalid [−][src]
#[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.
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 Option<OwnedHandle>
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, or equal to INVALID_HANDLE_VALUE
(-1). It must not be null.
Note that not all Windows APIs use INVALID_HANDLE_VALUE
for errors;
see here for the full story.