#ifndef _NTIOAPI_H

/**
 * The FILE_STANDARD_INFORMATION structure contains standard information of a file.
 * \remarks EndOfFile specifies the byte offset to the end of the file.
 * Because this value is zero-based, it actually refers to the first free byte in the file; that is, it is the offset to the byte immediately following the last valid byte in the file.
 * \sa https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/ns-wdm-_file_standard_information
 */
typedef struct _FILE_STANDARD_INFORMATION
{
    LARGE_INTEGER AllocationSize;       // The file allocation size in bytes. Usually, this value is a multiple of the sector or cluster size of the underlying physical device.
    LARGE_INTEGER EndOfFile;            // The end of file location as a byte offset.
    ULONG NumberOfLinks;                // The number of hard links to the file.
    BOOLEAN DeletePending;              // The delete pending status. TRUE indicates that a file deletion has been requested.
    BOOLEAN Directory;                  // The file directory status. TRUE indicates the file object represents a directory.
} FILE_STANDARD_INFORMATION, *PFILE_STANDARD_INFORMATION;

#endif
View code on GitHub

// wdm.h

typedef struct _FILE_STANDARD_INFORMATION {
  LARGE_INTEGER AllocationSize;
  LARGE_INTEGER EndOfFile;
  ULONG         NumberOfLinks;
  BOOLEAN       DeletePending;
  BOOLEAN       Directory;
} FILE_STANDARD_INFORMATION, *PFILE_STANDARD_INFORMATION;
View the official Windows Driver Kit DDI reference