#ifndef _NTIOAPI_H
typedef struct _FILE_COMPRESSION_INFORMATION
{
    LARGE_INTEGER CompressedFileSize;
    USHORT CompressionFormat;
    UCHAR CompressionUnitShift;
    UCHAR ChunkShift;
    UCHAR ClusterShift;
    UCHAR Reserved[3];
} FILE_COMPRESSION_INFORMATION, *PFILE_COMPRESSION_INFORMATION;
View code on GitHubThis structure is documented in Windows Driver Kit.