[Setup]
AppName=My Program
AppVersion=1.0
DefaultDirName={pf}\My Program
 
[Code]
 
type
  TDriveType = (
    dtUnknown,
    dtNoRootDir,
    dtRemovable,
    dtFixed,
    dtRemote,
    dtCDROM,
    dtRAMDisk
  );
 
  TDriveTypes = set of TDriveType;
 
  // Las funciones las declaré en modo ANSI.
 
  function GetDriveType(lpRootPathName: string): UINT;
  external 'GetDriveTypeA@kernel32.dll stdcall';
 
  function GetLogicalDriveStrings(nBufferLength: DWORD; lpBuffer: string): DWORD;
  external 'GetLogicalDriveStringsA@kernel32.dll stdcall';
 
function IntToDriveType(Value: UINT): TDriveType;
begin
  Result := dtUnknown;
  case Value of
    1: Result := dtNoRootDir;
    2: Result := dtRemovable;
    3: Result := dtFixed;
    4: Result := dtRemote;
    5: Result := dtCDROM;
    6: Result := dtRAMDisk;
  end;
end;
 
function GetLogicalDrives(var ADrives: array of string; AFilter: TDriveTypes): Integer;
var
  S: string;
  I: Integer;
  DriveRoot: string;
begin
  Result := 0;
  SetArrayLength(ADrives, 0);
 
  I := GetLogicalDriveStrings(0, #0);
  if I > 0 then
  begin
    SetLength(S, I);
    if GetLogicalDriveStrings(Length(S), S) > 0 then
    begin
      S := TrimRight(S);
      I := Pos(#0, S);
      while I > 0 do
      begin
        DriveRoot := Copy(S, 1, I - 1);
        if (AFilter = []) or
          (IntToDriveType(GetDriveType(DriveRoot)) in AFilter) then
        begin
          SetArrayLength(ADrives, GetArrayLength(ADrives) + 1);
          ADrives[GetArrayLength(ADrives) - 1] := DriveRoot;
        end;
        Delete(S, 1, I);
        I := Pos(#0, S);
      end;
      Result := GetArrayLength(ADrives);
    end;
  end;
end;
 
 
function CheckForFile(Filename: string; DriveType: TDriveTypes): Boolean; 
var
  I: Integer;
  DriveCount: Integer;
  DriveArray: array of string;
 
begin
  DriveCount := GetLogicalDrives(DriveArray, DriveType);
  for I := 0 to DriveCount - 1 do
    begin
		if FileExists(DriveArray[I] + Filename) then
		    begin
				// MsgBox('File was found on path: ' + DriveArray[I] + Filename, mbInformation, MB_OK);
				Result := True;
				Break;
			end;		
	end;	
end;
 
function InitializeSetup: Boolean;
begin
  Result := CheckForFile('bin\game.exe', [dtCDROM])
  if Not Result then
	begin
		MsgBox('File does not exist on any CD-ROM drive, install stops', mbCriticalError, MB_OK);
	end;
end;