def clean_file(self):
    file = self.cleaned_data.get('file', '')
    #check a file in form for viruses
    if file:
        from tempfile import mkstemp
        import pyclamav
        import os
        tmpfile = mkstemp()[1]
        f = open(tmpfile, 'wb')
        f.write(file.content)
        f.close()
        isvirus, name = pyclamav.scanfile(tmpfile)
        os.unlink(tmpfile)
        if isvirus:
            raise forms.ValidationError( \
            "WARNING! Virus \"%s\" was detected in this file. \
            Check your system." % name)

    return file