# File lib/net/ftp.rb, line 443
    def storbinary(cmd, file, blocksize, rest_offset = nil, &block) # :yield: data
      if rest_offset
        file.seek(rest_offset, IO::SEEK_SET)
      end
      synchronize do
        voidcmd("TYPE I")
        conn = transfercmd(cmd, rest_offset)
        loop do
          buf = file.read(blocksize)
          break if buf == nil
          conn.write(buf)
          yield(buf) if block
        end
        conn.close
        voidresp
      end
    end