[wdmaudiodev] Re: KS Filter
- From: Anthony Palomba <APalomba@xxxxxxxxxxxx>
- To: "'wdmaudiodev@xxxxxxxxxxxxx'" <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Fri, 10 Jan 2003 10:07:42 -0600
I have a problem I was wondering if someone could help we with.
My audio driver is trying to register a device interface so that
another driver can find its symbolic name and open a connection
to it. The external driver calls IoGetDeviceInterfaces and then
calls ZwCreateFile with the symbolic name returned from
IoGetDeviceInterfaces.
The problem is ZwCreateFile always return STATUS_OBJECT_NAME_NOT_FOUND.
This is what I am doing(I have removed error checking so that I can paste it
all here)
PHANDLE FileHandle = NULL;
OBJECT_ATTRIBUTES oa;
IO_STATUS_BLOCK IoStatusBlock;
UNICODE_STRING Ustr;
PFILE_OBJECT FileObject;
PDEVICE_OBJECT DeviceObject;
IoGetDeviceInterfaces(&FOOBAR_DEVICE_INTERFACE, NULL, 0, &SymbolicLinkList);
RtlInitUnicodeString(&Ustr, SymbolicLinkList);
InitializeObjectAttributes(&oa, &Ustr,
OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE, NULL, NULL);
ntStatus = ZwCreateFile(FileHandle, GENERIC_READ | GENERIC_WRITE,
&oa, &IoStatusBlock, NULL, FILE_ATTRIBUTE_NORMAL, 0, FILE_OPEN, 0,
NULL, 0);
FOOBAR_DEVICE_INTERFACE is a guid that my audio driver registers as an
interface with IoRegisterDeviceInterface. It then enables it with
IoSetDeviceInterfaceState. When we call IoGetDeviceInterfaces from
my external driver we get a list of symbolic names. Each name is
separated by a NULL terminator with the whole list ending with an extra
NULL terminator. My code only handles the first entry in the list,
which is all right because we are the only device using this interface.
So the link between my audio driver and the registered interface definitely
exists because I am getting my devices symbolic name. The
question is, where is ZwCreateFile looking to resolve the symbolic name?
Anthony
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