OpenSSL::Buffering#do_write

# File tmp/rubies/ruby-4.0.0/ext/openssl/lib/openssl/buffering.rb, line 349
def do_write(s)
  @wbuffer = Buffer.new unless defined? @wbuffer
  @wbuffer.append_as_bytes(s)

  @sync ||= false
  buffer_size = @wbuffer.bytesize
  if @sync or buffer_size > BLOCK_SIZE
    nwrote = 0
    begin
      while nwrote < buffer_size do
        begin
          chunk = if nwrote > 0
            @wbuffer.byteslice(nwrote, @wbuffer.bytesize)
          else
            @wbuffer
          end

          nwrote += syswrite(chunk)
        rescue Errno::EAGAIN
          retry
        end
      end
    ensure
      if nwrote < @wbuffer.bytesize
        @wbuffer[0, nwrote] = ""
      else
        @wbuffer.clear
      end
    end
  end
end