Fix golangci-lint issues

internal/internal.go

@@ -1,6 +1,7 @@
 package internal
 
 import (
+	"crypto/md5"
 	"fmt"
 	"io"
 	"math"
@@ -180,7 +181,7 @@ func ParseWALSegmentPath(s string) (index int, offset int64, err error) {
 	if i32 > math.MaxInt32 {
 		return 0, 0, fmt.Errorf("index too large in wal segment path %q", s)
 	}
-	off64, _ := strconv.ParseInt(a[2], 16, 64)
+	off64, _ := strconv.ParseUint(a[2], 16, 64)
 	if off64 > math.MaxInt64 {
 		return 0, 0, fmt.Errorf("offset too large in wal segment path %q", s)
 	}
@@ -228,3 +229,8 @@ func TruncateDuration(d time.Duration) time.Duration {
 	}
 	return d
 }
+
+// MD5hash returns a hex-encoded MD5 hash of b.
+func MD5hash(b []byte) string {
+	return fmt.Sprintf("%x", md5.Sum(b))
+}

internal/testingutil/testingutil.go

@@ -1,9 +1,12 @@
 package testingutil
 
 import (
+	"bytes"
 	"io"
 	"os"
 	"testing"
+
+	"github.com/pierrec/lz4/v4"
 )
 
 // ReadFile reads all data from filename. Fail on error.
@@ -62,3 +65,26 @@ func Setenv(tb testing.TB, key, value string) func() {
 		}
 	}
 }
+
+func CompressLZ4(tb testing.TB, b []byte) []byte {
+	tb.Helper()
+
+	var buf bytes.Buffer
+	zw := lz4.NewWriter(&buf)
+	if _, err := zw.Write(b); err != nil {
+		tb.Fatal(err)
+	} else if err := zw.Close(); err != nil {
+		tb.Fatal(err)
+	}
+	return buf.Bytes()
+}
+
+func DecompressLZ4(tb testing.TB, b []byte) []byte {
+	tb.Helper()
+
+	buf, err := io.ReadAll(lz4.NewReader(bytes.NewReader(b)))
+	if err != nil {
+		tb.Fatal(err)
+	}
+	return buf
+}