//  dismount.c

#include <stdio.h>
#include <string.h>
#include <nt.h>
#include <ntrtl.h>
#include <nturtl.h>
#include <windows.h>

#include <ntioapi.h>

VOID
_cdecl
main(
    int argc,
    char *argv[]
    )
{
    HANDLE Volume;
    IO_STATUS_BLOCK IoStatusBlock;
    NTSTATUS Status;
    OBJECT_ATTRIBUTES ObjAttr;
    ANSI_STRING AnsiName;
    UNICODE_STRING UnicodeName;
    char DriveNameBuffer[32];


    //
    //  Get parameter
    //

    if (argc < 2) {
    
        printf("This program dismounts a volume.\n\n");
        printf("usage: %s <driveletter>:\n", argv[0]);
        return;
    }

    strcpy( DriveNameBuffer, "\\DosDevices\\" );
    strcat( DriveNameBuffer, argv[1] );
    RtlInitAnsiString( &AnsiName, DriveNameBuffer );
    Status = RtlAnsiStringToUnicodeString( &UnicodeName, &AnsiName, TRUE );

    if (!NT_SUCCESS(Status)) {
    
        printf( "Error initalizing strings" );
        return;
    }

    RtlZeroMemory( &ObjAttr, sizeof(OBJECT_ATTRIBUTES) );
    ObjAttr.Length = sizeof(OBJECT_ATTRIBUTES);
    ObjAttr.ObjectName = &UnicodeName;
    ObjAttr.Attributes = OBJ_CASE_INSENSITIVE;
    
    Status = NtOpenFile( &Volume,
                         SYNCHRONIZE | FILE_READ_DATA | FILE_WRITE_DATA,
                         &ObjAttr,
                         &IoStatusBlock,
                         FILE_SHARE_READ | FILE_SHARE_WRITE,
                         FILE_SYNCHRONOUS_IO_ALERT );

    if (Volume == INVALID_HANDLE_VALUE) {
    
        printf( "Error opening file %s %x\n", argv[1], GetLastError() );
        return;
    }

    Status = NtFsControlFile( Volume,                          // file handle
                              NULL,                            // event
                              NULL,                            // apc routine
                              NULL,                            // apc context
                              &IoStatusBlock,                  // iosb
                              FSCTL_DISMOUNT_VOLUME,           // FsControlCode
                              NULL,                            // input buffer
                              0,                               // input buffer length
                              NULL,                            // OutputBuffer for data from the FS
                              0);                              // OutputBuffer Length

    if (Status == STATUS_SUCCESS) {

        printf( "\nDismount succeeded." );

    } else {

        printf( "\nDismount failed with status %x", Status );
    }

    CloseHandle( Volume );
}