Add safe formatting function

utils/safe.go

@@ -0,0 +1,21 @@
+package utils
+
+import (
+	"encoding/hex"
+	"strings"
+)
+
+func SafeFirst16Bytes(data []byte) string {
+	if len(data) == 0 {
+		return "<empty>"
+	}
+
+	return strings.TrimPrefix(
+		strings.SplitN(hex.Dump(data), "\n", 2)[0],
+		"00000000  ",
+	)
+}
+
+func SafeFirst16Chars(s string) string {
+	return SafeFirst16Bytes([]byte(s))
+}

utils/safe_test.go

@@ -0,0 +1,27 @@
+package utils
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSafeFirst16(t *testing.T) {
+	assert.Equal(t,
+		"47 6f 20 69 73 20 61 6e  20 6f 70 65 6e 20 73 6f  |Go is an open so|",
+		SafeFirst16Bytes([]byte("Go is an open source programming language.")),
+	)
+	assert.Equal(t,
+		"47 6f 20 69 73 20 61 6e  20 6f 70 65 6e 20 73 6f  |Go is an open so|",
+		SafeFirst16Chars("Go is an open source programming language."),
+	)
+
+	assert.Equal(t,
+		"<empty>",
+		SafeFirst16Bytes(nil),
+	)
+	assert.Equal(t,
+		"<empty>",
+		SafeFirst16Chars(""),
+	)
+}