How to call a list of the physically attached hard disks using Free Pascal, or, failing that, Delphi?

Question

Further to this question and this one that I asked more recently but without the correct specifics...and lastly this one that I asked at the Free Pascal forum specifically....

Can anyone provide me with guidance, examples or a link to something somewhere that explains how to call a list of the physically attached hard disks using Free Pascal, or, failing that, Delphi, regardless of whether the disks have been mounted by the operating system or not? An example is shown in the screenshot of what I am trying to achive (what is shown in this screenshot is by another software product). So pulling a list of logical volumes (C:\, E:\ etc) is not what I am trying to do. And if the disk has a filesystem that the operating system cannot mount, I still want to see the physical disk listed.

I stress that C\C++\C Sharp examples are plentifull but not what I am after. I need primarily Free Pascal example, or, failing that, Delphi.

Statampere

+1 this question shows research effort :-) Have you looked at the source code for TDriveComboBox under the Win3.1 components? – Jezabelle

I have strong belief what kernel uses contiguos numbering for phy disks, so you just enumerate until failure – Lactation

Answer 1

Try the Win32_DiskDrive WMI class, check this sample code

{$mode objfpc}{$H+}
uses
  SysUtils,ActiveX,ComObj,Variants;
{$R *.res}

// The Win32_DiskDrive class represents a physical disk drive as seen by a computer running the Win32 operating system. Any interface to a Win32 physical disk drive is a descendent (or member) of this class. The features of the disk drive seen through this object correspond to the logical and management characteristics of the drive. In some cases, this may not reflect the actual physical characteristics of the device. Any object based on another logical device would not be a member of this class.
// Example: IDE Fixed Disk.

procedure  GetWin32_DiskDriveInfo;
const
  WbemUser            ='';
  WbemPassword        ='';
  WbemComputer        ='localhost';
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : Variant;
  oEnum         : IEnumvariant;
  sValue        : string;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer(WbemComputer, 'root\CIMV2', WbemUser, WbemPassword);
  FWbemObjectSet:= FWMIService.ExecQuery('SELECT * FROM Win32_DiskDrive','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  while oEnum.Next(1, FWbemObject, nil) = 0 do
  begin
    sValue:= FWbemObject.Properties_.Item('Caption').Value;
    Writeln(Format('Caption        %s',[sValue]));// String
    sValue:= FWbemObject.Properties_.Item('DeviceID').Value;
    Writeln(Format('DeviceID       %s',[sValue]));// String
    sValue:= FWbemObject.Properties_.Item('Model').Value;
    Writeln(Format('Model          %s',[sValue]));// String
    sValue:= FWbemObject.Properties_.Item('Partitions').Value;
    Writeln(Format('Partitions     %s',[sValue]));// Uint32
    sValue:= FWbemObject.Properties_.Item('PNPDeviceID').Value;
    Writeln(Format('PNPDeviceID    %s',[sValue]));// String
    sValue:= FormatFloat('#,', FWbemObject.Properties_.Item('Size').Value / (1024*1024));
    Writeln(Format('Size           %s mb',[sValue]));// Uint64

    Writeln;
    FWbemObject:= Unassigned;
  end;
end;

begin
  try
    GetWin32_DiskDriveInfo;
  except
    on E:EOleException do
        Writeln(Format('EOleException %s %x', [E.Message,E.ErrorCode]));
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
  end;
  Writeln('Press Enter to exit');
  Readln;
end.    

After of running this code you will get a output like this

Germanize

Answer 2

For mounted drives with drive letters, call Win32 ShellApi function SHGetSpecialFolderLocation(0, CSIDL_DRIVES, Drives). Declare local variable Drives: PItemIdList. This is in unit named ShellAPI in delphi. Hopefully a similar unit exists in FreePascal.

For unmounted drives, you will have to enumerate the device drivers by the device driver class of GUID_DEVINTERFACE_DISK somehow. The SetupAPI of windows should be able to help you.

You can get SetupAPI.pas from the JEDI JCL or JEDI API projects.

procedure GetListFromSetupApi(aStrings: TStrings);
var
  iDev: Integer;
  RegDataType: Cardinal;
  reqSize:DWORD;
  prop:Cardinal;
  pszData:PByte;
  hinfo:   HDEVINFO;
  bResult: BOOL;
  devinfo: SP_DEVINFO_DATA;
  dwRequiredSize,dwPropertyRegDataType,dwAllocSz:Cardinal;
begin
  LoadSetupApi;
  if not Assigned(SetupDiGetClassDevs) then
    Exit;

  hinfo := SetupDiGetClassDevs(@GUID_DEVINTERFACE_DISK, nil, HWND(nil),
                               DIGCF_DEVICEINTERFACE or DIGCF_PRESENT or DIGCF_PROFILE);

  devinfo.ClassGuid.D1 := 0;
  devinfo.ClassGuid.D2 := 0;
  devinfo.ClassGuid.D3 := 0;
  devinfo.cbSize := SizeOf(SP_DEVINFO_DATA);

  iDev := 0;
   while SetupDiEnumDeviceInfo(hinfo, iDev, devinfo) do
    begin

    dwRequiredSize := 0;

    prop := SPDRP_PHYSICAL_DEVICE_OBJECT_NAME;
    // results on my computer:
    // \Device\Ide\IAAStorageDevice-1
    // \Device\Ide\IAAStorageDevice-2
    // \Device\0000008a                 (this one is a usb disk, use SPDRP_ENUMERATOR_NAME, returns USBSTOR)

//   prop := SPDRP_ENUMERATOR_NAME; // results: IDE, USBSTOR, or other bus type.

//   prop := SPDRP_LOCATION_INFORMATION; // a number like 1,2,3.


    { SPDRP_DRIVER - driver guid }
    { Get Size of property }
     SetupDiGetDeviceRegistryProperty
                (hinfo,
                devinfo,
                prop,
                dwPropertyRegDataType,
                nil,
                0,
                dwRequiredSize);   { dwRequiredSize should be around 88 after this point, in unicode delphi }

     if dwRequiredSize>0 then begin

        dwAllocSz := dwRequiredSize+4;
        pszData := AllocMem(dwAllocSz);
        bResult := SetupDiGetDeviceRegistryProperty
                (hinfo,
                devinfo,
                prop,
                dwPropertyRegDataType,
                pszData,
                dwAllocSz,
                dwRequiredSize);

        aStrings.Add(IntToStr(aStrings.Count)+': '+PChar(pszData));
        FreeMem(pszData);

    end;
    inc(iDev);
  end;
  SetupDiDestroyDeviceInfoList(hinfo);
end;

A complete working DELPHI example including the above code and the appropriate JEDI API units is here. You can adapt it to free pascal and lazarus pretty easily.

Buckels

RRUZ - thank you very very much! I have just tried the code you pasted into a new basic terminal program using Lazarus 0.9.31 and FPC 2.5.1, and it worked straight away without having to change anything. I just compiled and built it then ran the compiled exe, and sure enough, it does exactly what I need. Now I can implement it into my own project. You have helped me achieve something that I have spent countless hours trying to do! Bless you! – Statampere