OpenSSL::Buffering#do_write

# File tmp/rubies/ruby-3.0.5/ext/openssl/lib/openssl/buffering.rb, line 337
def do_write(s)
  @wbuffer = Buffer.new unless defined? @wbuffer
  @wbuffer << s
  @wbuffer.force_encoding(Encoding::BINARY)
  @sync ||= false
  if @sync or @wbuffer.size > BLOCK_SIZE
    until @wbuffer.empty?
      begin
        nwrote = syswrite(@wbuffer)
      rescue Errno::EAGAIN
        retry
      end
      @wbuffer[0, nwrote] = ""
    end
  end
end