Delphi

Found in the Win32.hlp

type
PTokenUser = ^TTokenUser;
_TOKEN_USER = record
User: TSIDAndAttributes;
end;
TTokenUser = _TOKEN_USER;

procedure getCurrentUserAndDomain(var User, Domain: String);
var
hProcess, hAccessToken: THandle;
InfoBuffer: array[0..1000] of Char;
szAccountName, szDomainName: array [0..200] of Char;
dwInfoBufferSize, dwAccountSize, dwDomainSize: DWORD;
pUser: PTokenUser;
snu: SID_NAME_USE;
begin
dwAccountSize:=200;
dwDomainSize:=200;
hProcess:=GetCurrentProcess;
OpenProcessToken(hProcess,TOKEN_READ,hAccessToken);
GetTokenInformation(hAccessToken,TokenUser,@InfoBuffer[0],1000,
dwInfoBufferSize);
pUser:=PTokenUser(@InfoBuffer[0]);
LookupAccountSid(nil, pUser.User.Sid, szAccountName, dwAccountSize, szDomainName, dwDomainSize, snu);
User:=szAccountName;
Domain:=szDomainName;
CloseHandle(hAccessToken);
end;