function GetImageSize(Instance:THandle):Cardinal;
var
  Index:Integer;
  Header:PImageNtHeaders;
begin
  Result:=0;
  Inc(Instance,PImageDosHeader(Instance)._lfanew);
  Header:=PImageNtHeaders(Instance);
  Inc(Instance,SizeOf(TImageNtHeaders));
  for Index:=1 to Header.FileHeader.NumberOfSections do begin
    with PImageSectionHeader(Instance)^ do
      if PointerToRawData+SizeOfRawData>Result then
        Result:=PointerToRawData+SizeOfRawData;
    Inc(Instance,SizeOf(TImageSectionHeader));
  end;
end;

function GetImageSize(const FileName:string):Cardinal;
var
  ExeFile:HFile;
  MZHeader:TImageDosHeader;
  PEHeader:TImageNtHeaders;
  ISHeader:TImageSectionHeader;
  Readed,MaxEnd:Cardinal;
  A:Integer;
begin
  Result:=0;
  ExeFile:=CreateFile(PChar(FileName),GENERIC_READ,FILE_SHARE_READ,nil,OPEN_EXISTING,0,0);
  if ExeFile<>INVALID_HANDLE_VALUE then try
    if ReadFile(ExeFile,MZHeader,SizeOf(MZHeader),Readed,nil)and(Readed=SizeOf(MZHeader))
      and(MZHeader.e_magic=$5A4D)
    and(SetFilePointer(ExeFile,MZHeader._lfanew,nil,FILE_BEGIN)=DWORD(MZHeader._lfanew))
      and ReadFile(ExeFile,PEHeader,SizeOf(PEHeader),Readed,nil)and(Readed=SizeOf(PEHeader))
      and(PEHeader.Signature=$4550) then begin
      MaxEnd:=0;
      for A:=0 to PEHeader.FileHeader.NumberOfSections-1 do begin
        if not ReadFile(ExeFile,ISHeader,SizeOf(ISHeader),Readed,nil)
          or(Readed<>SizeOf(ISHeader)) then Exit;
        with ISHeader do
          if PointerToRawData+SizeOfRawData>Result then
            MaxEnd:=PointerToRawData+SizeOfRawData;
      end;
      Result:=Min(MaxEnd,GetFileSize(ExeFile,nil));
    end
  finally
    CloseHandle(ExeFile);
  end;
end;