Get valid drive letter and is occupied

Question

I want scan all available drive letter that exist on my computer, and get detail with it (chk if occupied, chk for type and size).

I have no problem about how to get size by using the codes bellow

var
  FreeAvail, totalSpace: Int64;
begin
  if SysUtils.GetDiskFreeSpaceEx(PChar('F:\'), FreeAvail, totalSpace, nil) = True
  then
  begin
    F1.Liner('Drive F total space ');
    F1.pBold(IntToStr(totalSpace div (1024 * 1024 * 1024)) + ' GB ,');
    F1.Liner(' available free space ');
    F1.pBold(IntToStr(FreeAvail div (1024 * 1024 * 1024)) + ' GB.');
  end;
end;

But if the drive is unoccupied, i don't like this situation.

Question: How to get available ALL drive(s) - CDROM, USB Stick, etc. To be more specific, i want the display result like this example;

Drive E [Local Disk] - TotalSpace 500 GB - FreeSpace 200 GB

Drive F [CD Drive] - Unoccupied - FreeSpace 0

Drive G [Removable] - TotalSpace 8 GB - FreeSpace 2 GB

Answer 1

I've provided a couple of functions that might help. The first uses the Win32 API function GetLogicalDriveStrings to retrieve a list of the assigned drive letters on the computer. The second queries a drive to see if it's ready for use (has a disk in it). (There's also a utility function that converts a drive letter to the integer value needed for DiskSize, the old Pascal I/O function.)

The code has worked since Win95 days, and was just tested on Win7 64-bit in a Delphi 2007 console application. There's a console test application included below.

program Project2;

{$APPTYPE CONSOLE}

uses
  SysUtils, Windows, Types;

// Returns an array filled wit the assigned
// drive letters on the current computer.
function  GetDriveList: TStringDynArray;
var
  Buff: array[0..128] of Char;
  ptr: PChar;
  Idx: Integer;
begin
  if (GetLogicalDriveStrings(Length(Buff), Buff) = 0) then
    RaiseLastOSError;
  // There can't be more than 26 lettered drives (A..Z).
  SetLength(Result, 26);      

  Idx := 0;
  ptr := @Buff;
  while StrLen(ptr) > 0 do
  begin
    Result[Idx] := ptr;
    ptr := StrEnd(ptr);
    Inc(ptr);
    Inc(Idx);
  end;
  SetLength(Result, Idx);
end;

// Converts a drive letter into the integer drive #
// required by DiskSize().
function DOSDrive( const sDrive: String ): Integer;
begin
  if (Length(sDrive) < 1) then
    Result := -1
  else
    Result := (Ord(UpCase(sDrive[1])) - 64);
end;

// Tests the status of a drive to see if it's ready
// to access. 
function DriveReady(const sDrive: String): Boolean;
var
  ErrMode: Word;
begin
  ErrMode := SetErrorMode(0);
  SetErrorMode(ErrMode or SEM_FAILCRITICALERRORS);
  try
    Result := (DiskSize(DOSDrive(sDrive)) > -1);
  finally
    SetErrorMode(ErrMode);
  end;
end;

// Demonstrates using the above functions.
var
  DrivesArray: TStringDynArray;
  Drive: string;
const
  StatusStr = 'Drive %s is ready: %s';
begin
  DrivesArray := GetDriveList;
  for Drive in  DrivesArray do
    WriteLn(Format(StatusStr, [Drive, BoolToStr(DriveReady(Drive), True)]));
  ReadLn;
end.

Sample output when run on my system (Win7 64, two physical hard drives (C: and D:), an ISO device with no image mounted (E:), and a DVD drive (Z:).

Drive C:\ is ready: True 
Drive D:\ is ready: True 
Drive E:\ is ready: False
Drive Z:\ is ready: True