FltGetVolumeProperties function (fltkernel.h)

Article
10/21/2021

The FltGetVolumeProperties routine returns volume property information for the given volume.

Syntax

NTSTATUS FLTAPI FltGetVolumeProperties(
  [in]  PFLT_VOLUME            Volume,
  [out] PFLT_VOLUME_PROPERTIES VolumeProperties,
        ULONG                  VolumePropertiesLength,
  [out] PULONG                 LengthReturned
);

Parameters

[in] Volume

Opaque pointer for the volume. This parameter is required and cannot be NULL.

[out] VolumeProperties

Pointer to a caller-allocated buffer that receives the requested volume property information. If Length is zero on input, this parameter is ignored. Otherwise, this parameter is required and cannot be NULL.

VolumePropertiesLength

Size, in bytes, of the buffer pointed to by the VolumeProperties parameter. This parameter is optional and can be zero. If it is zero, LengthReturned receives the size, in bytes, of the buffer needed to hold the volume properties. If this parameter is nonzero, it must be at least the value of sizeof(FLT_VOLUME_PROPERTIES).

[out] LengthReturned

Pointer to a caller-allocated variable that receives the size, in bytes, of the information returned in VolumeProperties. If FltGetVolumeProperties returns STATUS_BUFFER_TOO_SMALL, or if Length is zero on input, this parameter instead receives the size, in bytes, of the buffer needed to hold the volume properties. This parameter is required and cannot be NULL.

Return value

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

Return code	Description
STATUS_BUFFER_OVERFLOW	The buffer that the VolumeProperties parameter points to is large enough to hold the fixed portion of the FLT_VOLUME_PROPERTIES structure but not the FileSystemDriverName, FileSystemDeviceName, or RealDeviceName members. In this case, only the fixed portion of the volume information is returned in the buffer pointed to by the VolumeProperties parameter. The LengthReturned parameter receives the actual length, in bytes, of data returned. This is a warning code.
STATUS_BUFFER_TOO_SMALL	The buffer that the VolumeProperties parameter points to is not large enough to hold the volume property information. The LengthReturned parameter receives the required buffer size. In this case, no volume information is returned. This is an error code.

Return code

Description

STATUS_BUFFER_OVERFLOW

The buffer that the VolumeProperties parameter points to is large enough to hold the fixed portion of the FLT_VOLUME_PROPERTIES structure but not the FileSystemDriverName, FileSystemDeviceName, or RealDeviceName members. In this case, only the fixed portion of the volume information is returned in the buffer pointed to by the VolumeProperties parameter. The LengthReturned parameter receives the actual length, in bytes, of data returned. This is a warning code.

STATUS_BUFFER_TOO_SMALL

The buffer that the VolumeProperties parameter points to is not large enough to hold the volume property information. The LengthReturned parameter receives the required buffer size. In this case, no volume information is returned. This is an error code.

Remarks

FltGetVolumeProperties only returns information that can safely be queried during the mount process without risk of a system deadlock. Therefore, a minifilter driver commonly calls this routine from a post-mount callback function or an InstanceSetupCallback (PFLT_INSTANCE_SETUP_CALLBACK) routine to determine whether to attach to a given volume.

Requirements

Requirement	Value
Target Platform	Universal
Header	fltkernel.h (include Fltkernel.h)
Library	FltMgr.lib
DLL	Fltmgr.sys
IRQL	<= APC_LEVEL