very bad demo code

pkg/envoy/extract_embed.go

@@ -0,0 +1,43 @@
+//go:build !debug_local_envoy
+
+package envoy
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/pomerium/pomerium/pkg/envoy/files"
+)
+
+func extract(dstName string) (err error) {
+	checksum, err := hex.DecodeString(strings.Fields(files.Checksum())[0])
+	if err != nil {
+		return fmt.Errorf("checksum %s: %w", files.Checksum(), err)
+	}
+
+	hr := &hashReader{
+		Hash: sha256.New(),
+		r:    bytes.NewReader(files.Binary()),
+	}
+
+	dst, err := os.OpenFile(dstName, os.O_CREATE|os.O_WRONLY, ownerRX)
+	if err != nil {
+		return err
+	}
+	defer func() { err = dst.Close() }()
+
+	if _, err = io.Copy(dst, io.LimitReader(hr, maxExpandedEnvoySize)); err != nil {
+		return err
+	}
+
+	sum := hr.Sum(nil)
+	if !bytes.Equal(sum, checksum) {
+		return fmt.Errorf("expected %x, got %x checksum", checksum, sum)
+	}
+	return nil
+}