FltEnumerateInstanceInformationByFilter function (fltkernel.h)

Article
10/21/2021

The FltEnumerateInstanceInformationByFilter routine provides information about instances of a given minifilter driver.

Syntax

NTSTATUS FLTAPI FltEnumerateInstanceInformationByFilter(
  [in]  PFLT_FILTER                Filter,
  [in]  ULONG                      Index,
  [in]  INSTANCE_INFORMATION_CLASS InformationClass,
  [out] PVOID                      Buffer,
  [in]  ULONG                      BufferSize,
  [out] PULONG                     BytesReturned
);

Parameters

[in] Filter

Opaque filter pointer for the caller.

[in] Index

Zero-based index of the instance for which the information is requested.

[in] InformationClass

Type of information requested. This parameter can have one of the following values.

Value	Meaning
InstanceBasicInformation	The buffer pointed to by the Buffer parameter receives an INSTANCE_BASIC_INFORMATION structure for the instance.
InstanceFullInformation	The buffer pointed to by the Buffer parameter receives an INSTANCE_FULL_INFORMATION structure for the instance.
InstancePartialInformation	The buffer pointed to by the Buffer parameter receives an INSTANCE_PARTIAL_INFORMATION structure for the instance.
InstanceAggregateStandardInformation	The buffer pointed to by the Buffer parameter receives an INSTANCE_AGGREGATE_STANDARD_INFORMATION structure for the instance. The LegacyFilter portion of the structure is not utilized. This structure is available starting with Windows Vista.

[out] Buffer

Pointer to a caller-allocated buffer that receives the requested information. The type of the information returned in the buffer is defined by the InformationClass parameter.

[in] BufferSize

Size, in bytes, of the buffer that the Buffer parameter points to. The caller should set this parameter according to the given InformationClass value.

[out] BytesReturned

Pointer to a caller-allocated variable that receives the number of bytes returned in the buffer that Buffer points to. If the input value of BufferSize is too small, FltEnumerateInstanceInformationByFilter returns STATUS_BUFFER_TOO_SMALL and sets this variable to the number of bytes required to store the requested information. This parameter is required and cannot be NULL.

Return value

FltEnumerateInstanceInformationByFilter returns STATUS_SUCCESS or an appropriate NTSTATUS value, such as one of the following:

Return code	Description
STATUS_BUFFER_TOO_SMALL	The buffer that the Buffer parameter points to is not large enough to store the requested information. This is an error code.
STATUS_FLT_DELETING_OBJECT	A matching instance was found, but it is being torn down. This is an error code.
STATUS_INVALID_PARAMETER	An invalid value was specified for the InformationClass parameter. For example, if FilterAggregateStandardInformation is specified on an operating system prior to Windows Vista, the routine will return STATUS_INVALID_PARAMETER. This is an error code.
STATUS_NO_MORE_ENTRIES	There are no more entries in the minifilter driver's instance list. This is a warning code.

Remarks

The Index parameter is simply a way for FltEnumerateInstanceInformationByFilter to select among instances in the instance list for the minifilter driver specified by Filter. Because the minifilter driver instances in the instance list can change at any time, two calls to FltEnumerateInstanceInformationByFilter with the same Index and Filter values are not guaranteed to return the same result.

To enumerate all registered minifilter drivers, call FltEnumerateFilters.

To list filter information for all registered minifilter drivers, call FltEnumerateFilterInformation.

To get filter information for a given minifilter driver, call FltGetFilterInformation.

To enumerate all minifilter driver instances on a given volume, call FltEnumerateInstanceInformationByVolume.

To enumerate instances of all minifilter drivers on all volumes, call FltEnumerateInstances.

To enumerate all volumes that are known to the Filter Manager, call FltEnumerateVolumes.

Requirements

Requirement	Value
Target Platform	Universal
Header	fltkernel.h (include FltKernel.h)
Library	FltMgr.lib
IRQL	<= APC_LEVEL