FltEnumerateVolumeInformation function (fltkernel.h)

Article
10/21/2021

The FltEnumerateVolumeInformation routine provides information about volumes that are known to the filter manager.

Syntax

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

Parameters

[in] Filter

Opaque filter pointer for the minifilter driver. This pointer uniquely identifies the minifilter driver and remains constant as long as the minifilter driver is loaded.

[in] Index

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

[in] InformationClass

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

Value	Meaning
FilterVolumeBasicInformation	The Buffer parameter receives a FILTER_VOLUME_BASIC_INFORMATION structure for the volume.
FilterVolumeStandardInformation	The Buffer parameter receives a FILTER_VOLUME_STANDARD_INFORMATION structure for the volume. 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, FltEnumerateVolumeInformation 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

FltEnumerateVolumeInformation 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 volume 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 FilterVolumeStandardInformation is specified on an operating system prior to Windows Vista, the routine returns STATUS_INVALID_PARAMETER. This is an error code.
STATUS_NO_MORE_ENTRIES	There are no more entries in the global list of volumes. This is a warning code.

Remarks

Using the Index parameter is simply a way for the FltEnumerateVolumeInformation routine to select among volumes in the filter manager's global list of volumes. Two calls to FltEnumerateVolumeInformation with the same value of the Index parameter do not necessarily return the same result because volumes can be mounted or dismounted at any time.

If FltEnumerateVolumeInformation is used to create a list of volume information structures, it is possible for two or more of these structures to contain identical volume names. For more information, see Understanding Volume Enumerations with Duplicate Volume Names.

To enumerate all registered minifilter drivers, call FltEnumerateFilters.

To enumerate all volumes that are known to the filter manager, call FltEnumerateVolumes.

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 instances of a given minifilter driver, call FltEnumerateInstanceInformationByFilter.

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

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

Requirements

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