How to get "disk serial number"

I need compare a decrypted string with the serial number of the disk where it is installed, as a way to avoid people to duplicate the software I deliver to them. I have not heard from a clever method to get access to that serial number string.
I presently achieve it (Delphi 1 Windows 3.11) with a not very clever method, though efficient : I use ShellExecute passing the command "command.com /c dir c:\ >text.tmp", launching the DOS command interpreter, using the DIR command, and redirecting the output into a text file, from which I read the line where the useful information is written. Do you have any clever method avoiding this call to DOS ?
pousticroustiAsked:
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erajojCommented:
With Win32, this is easy. But with Windows 3.x & Delphi 1, it's worth the 200 pts.
This code is tested and it works fine:

var
  Form1   : TForm1;
  SerialNo: LongInt;

implementation

{$R *.DFM}

type
  TDriveChar = '@'..'Z'; {'@' = current, 'A', 'B', etc.}

  PRealModeRegs = ^TRealModeRegs;
  TRealModeRegs = record
    case Integer of
      0: (
        EDI, ESI, EBP, EXX, EBX, EDX, ECX, EAX: Longint;
        Flags, ES, DS, FS, GS, IP, CS, SP, SS: Word);
      1: (
        DI, DIH, SI, SIH, BP, BPH, XX, XXH: Word;
        case Integer of
          0: (
            BX, BXH, DX, DXH, CX, CXH, AX, AXH: Word);
          1: (
            BL, BH, BLH, BHH, DL, DH, DLH, DHH,
            CL, CH, CLH, CHH, AL, AH, ALH, AHH: Byte));
  end;

function RealModeInt(Int: Byte; var Regs: TRealModeRegs): Boolean;
{ procedure invokes int 31h function 0300h to simulate a real mode }
{ interrupt from protected mode. }
var
  ErrorFlag: Boolean;
begin
  asm
    mov ErrorFlag, 0       { assume success }
    mov ax, 0300h          { function 300h }
    mov bl, Int            { real mode interrupt to execute }
    mov bh, 0              { required }
    mov cx, 0              { stack words to copy, assume zero }
    les di, Regs           { es:di = Regs }
    int 31h                { DPMI int 31h }
    jnc @@End              { carry flag set on error }
  @@Error:
    mov ErrorFlag, 1       { return false on error }
  @@End:
  end;
  Result := not ErrorFlag;
end;

function GetVolSerNo(Drive: TDriveChar): LongInt;
type
  PDiskInfo = ^TDiskInfo;
  TDiskInfo = record
    InfoLevel: Word;
    DiskSerNum: LongInt;
    VolumeLabel: array[0..10] of Byte;
    FileSysType: array[0..7] of Byte;
  end;
var
  L: LongInt;
  P: PDiskInfo;
  R: TRealModeRegs;
begin
  Result := 0;
  L := GlobalDOSAlloc(SizeOf(TDiskInfo));
  if L <> 0 then
  try
    P := Ptr(LoWord(L),0);
    FillChar(P^,sizeof(TDiskInfo),0);
    FillChar(R,sizeof(R),0);
    with R do
    begin
      AX := $6900;
      BL := Ord(Drive)-64;
      BH := 0;
      DS := HiWord(L);
      DX := 0;
    end;
    if RealModeInt($21,R) then
      Result := P^.DiskSerNum
  finally
    GlobalDosFree(LoWord(L));
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  SerialNo := GetVolSerNo('C');
  Label1.Caption := Format('%04x-%04x', [HiWord(SerialNo), LoWord(SerialNo)]); { Only to make it look like the "dir" output }
end;

Enjoy!

/// John

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pousticroustiAuthor Commented:
Thank you very much for this super fast answer. I trust I can rely on it, and will implement it right now. It's worth 200 points for you !
Olivier de Saint Leger
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