'Create a message, with text from the open file txt.'

def createmessage(self, n, txt):

    path = self.getmessagefilename(n)
    backuppath = self.getmessagefilename((',%d' % n))
    try:
        os.rename(path, backuppath)
    except os.error:
        pass
    ok = 0
    BUFSIZE = (16 * 1024)
    try:
        f = open(path, 'w')
        while 1:
            buf = txt.read(BUFSIZE)
            if (not buf):
                break
            f.write(buf)
        f.close()
        ok = 1
    finally:
        if (not ok):
            try:
                os.unlink(path)
            except os.error:
                pass
