nextOut, ok := w.buffer[w.nextOffset]
	if ok {
		n, err = w.w.Write(nextOut)
		delete(w.buffer, w.nextOffset)
		w.nextOffset += int64(n)
		if n != len(nextOut) {
			return 0, fmt.Errorf("expected write size %d but wrote %d bytes", len(nextOut), n)
		}
		if err != nil {
			return 0, err
		}
		goto again
	}

	return len(b), nil
}

func (f *sftpDriver) Filewrite(r *sftp.Request) (w io.WriterAt, err error) {

	// Call the ServeHTTP to execute the handler.
	apiRouter.ServeHTTP(rec, req)

	ctx, cancel := context.WithCancel(GlobalContext)
	defer cancel()

	// Now check if we actually wrote to backend (regardless of the response
	// returned by the server).
	z := obj.(*erasureServerPools)
	xl := z.serverPools[0].sets[0]
	erasureDisks := xl.getDisks()

		// Fan-out requires no copying, and must be carried from original source
		// https://en.wikipedia.org/wiki/Copy_protection so the incoming stream
		// is always going to be in-memory as we cannot re-read from what we
		// wrote to disk - since that amounts to "copying" from a "copy"
		// instead of "copying" from source, we need the stream to be seekable
		// to ensure that we can make fan-out calls concurrently.
		buf := bytebufferpool.Get()

```sh
./certgen -host "10.10.0.3,10.10.0.4,10.10.0.5"
```

A response similar to this one should be displayed:

```
2018/11/21 10:16:18 wrote public.crt
2018/11/21 10:16:18 wrote private.key
```

### 3.2 Use OpenSSL to Generate a Certificate

Use one of the following methods to generate a certificate using `openssl`:

	// Call the ServeHTTP to execute the handler.
	apiRouter.ServeHTTP(rec, req)

	ctx, cancel := context.WithCancel(GlobalContext)
	defer cancel()

	// Now check if we actually wrote to backend (regardless of the response
	// returned by the server).
	z := obj.(*erasureServerPools)
	xl := z.serverPools[0].sets[0]
	erasureDisks := xl.getDisks()

	fmt.Println(missing, "bytes missing. Truncating", len(filled)-lastValid-1, "from end.")
	mapped = mapped[:lastValid+1]
	err := os.WriteFile(out, mapped, os.ModePerm)
	if err != nil {
		return err
	}
	fmt.Println("Wrote output to", out)
	return nil