apiErr.Description = fmt.Sprintf("%s (%v)", apiErr.Description, multipart.ErrMessageTooLarge)
			writeErrorResponse(ctx, w, apiErr, r.URL)
			return
		}
		maxParts--

		name := part.FormName()
		if name == "" {
			continue
		}

		fileName = part.FileName()

		// Multiple values for the same key (one map entry, longer slice) are cheaper

// Continuation Message
// ====================
// Header specification
// --------------------
// Continuation messages contain two headers, as follows:
// https://docs.aws.amazon.com/AmazonS3/latest/API/images/s3select-frame-diagram-cont.png
//
// Payload specification
// ---------------------
// Continuation messages have no payload.
func genContinuationMessage() {
	buf := new(bytes.Buffer)

	buf.WriteByte(13)

	const fin = true
	var frame ws.Frame
	if s.ClientSide() {
		// We do not need to copy the payload, since we own it.
		payload := p

		frame = ws.NewFrame(op, fin, payload)
		frame = ws.MaskFrameInPlace(frame)
	} else {
		frame = ws.NewFrame(op, fin, p)
	}

	return ww.writeFrame(w, frame)
}

// writeFrame writes frame binary representation into w.

	// if tlsConfig != nil {
	// 	trhttp2, _ := http2.ConfigureTransports(tr)
	// 	if trhttp2 != nil {
	// 		// ReadIdleTimeout is the timeout after which a health check using ping
	// 		// frame will be carried out if no frame is received on the
	// 		// connection. 5 minutes is sufficient time for any idle connection.
	// 		trhttp2.ReadIdleTimeout = 5 * time.Minute

	"encoding/binary"
	"fmt"
	"hash/crc32"
	"net/http"
	"strconv"
	"sync/atomic"
	"time"
)

// A message is in the format specified in
// https://docs.aws.amazon.com/AmazonS3/latest/API/images/s3select-frame-diagram-frame-overview.png
// hence the calculation is made accordingly.
func totalByteLength(headerLength, payloadLength int) int {
	return 4 + 4 + 4 + headerLength + payloadLength + 4
}

}{
	{
		header: []byte{0x1f, 0x8b, 8},
		f:      formatGzip,
	},
	{
		// Zstd default header.
		header: []byte{0x28, 0xb5, 0x2f, 0xfd},
		f:      formatZstd,
	},
	{
		// Zstd skippable frame header.
		header: []byte{0x2a, 0x4d, 0x18},
		f:      formatZstd,
	},
	{
		// LZ4
		header: []byte{0x4, 0x22, 0x4d, 0x18},
		f:      formatLZ4,
	},
	{
		// Snappy/S2 stream