go/zodbpickle: Factor/generalize pickletools.Xstrbytes8 into here as zodbpickle.Unpack64

Similarly to ZODB/py which provides u64 and p64 utilities. Add
zodbpickle.Pack64 for symmetry.

go/internal/zodbpickle/zodbpickle.go

@@ -41,6 +41,8 @@
 package zodbpickle
 
 import (
+	"encoding/binary"
+	"fmt"
 	"io"
 
 	pickle "github.com/kisielk/og-rek"
@@ -77,3 +79,27 @@ func NewUnpickler(r io.Reader, loadref func(ref pickle.Ref) (any, error)) *pickl
 		PersistentLoad: loadref,
 	})
 }
+
+
+// ---- pack/unpack uint64 into [8]bytes ----
+
+// Pack64 packs uint64 into big-endian bytes.
+func Pack64(x uint64) pickle.Bytes {
+	var b [8]byte
+	binary.BigEndian.PutUint64(b[:], x)
+	return pickle.Bytes(b[:])
+}
+
+// Unpack64 tries to extract [8](bytestr|bytes) from unpickled value as big-endian uint64.
+func Unpack64(x interface{}) (uint64, error) {
+	s, err := pickle.AsBytes(x)
+	if err != nil {
+		return 0, err
+	}
+
+	if len(s) != 8 {
+		return 0, fmt.Errorf("expect [8]bytes; got [%d]bytes", len(s))
+	}
+
+	return binary.BigEndian.Uint64([]byte(s)), nil
+}

go/zodb/internal/pickletools/pickletools.go

-// Copyright (C) 2017-2024  Nexedi SA and Contributors.
-//                          Kirill Smelkov <kirr@nexedi.com>
-//
-// This program is free software: you can Use, Study, Modify and Redistribute
-// it under the terms of the GNU General Public License version 3, or (at your
-// option) any later version, as published by the Free Software Foundation.
-//
-// You can also Link and Combine this program with other software covered by
-// the terms of any of the Free Software licenses or any of the Open Source
-// Initiative approved licenses and Convey the resulting work. Corresponding
-// source of such a combination shall include the source code for all other
-// software used.
-//
-// This program is distributed WITHOUT ANY WARRANTY; without even the implied
-// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-//
-// See COPYING file for full licensing terms.
-// See https://www.nexedi.com/licensing for rationale and options.
-
-// Package pickletools provides utilities related to python pickles.
-//
-// It complements package ogórek (github.com/kisielk/og-rek).
-package pickletools
-
-import (
-	"encoding/binary"
-	"fmt"
-
-	pickle "github.com/kisielk/og-rek"
-)
-
-// Xstrbytes8 verifies and extracts [8](str|bytes) from unpickled value as big-endian u64.
-func Xstrbytes8(x interface{}) (uint64, error) {
-	s, err := pickle.AsBytes(x)
-	if err != nil {
-		return 0, err
-	}
-
-	if len(s) != 8 {
-		return 0, fmt.Errorf("expect [8]bytes; got [%d]bytes", len(s))
-	}
-
-	return binary.BigEndian.Uint64([]byte(s)), nil
-}

go/zodb/pydata.go

@@ -26,7 +26,6 @@ import (
 	"strings"
 
 	pickle "github.com/kisielk/og-rek"
-	"lab.nexedi.com/kirr/neo/go/zodb/internal/pickletools"
 	"lab.nexedi.com/kirr/neo/go/internal/zodbpickle"
 
 	"lab.nexedi.com/kirr/go123/xerr"
@@ -233,7 +232,7 @@ func xoid(x interface{}) (_ Oid, err error) {
 
 	// ZODB >= 5.4 encodes oid as bytes; before - as str:
 	// https://github.com/zopefoundation/ZODB/commit/12ee41c473
-	v, err := pickletools.Xstrbytes8(x)
+	v, err := zodbpickle.Unpack64(x)
 	if err != nil {
 		return InvalidOid, err
 	}

go/zodb/storage/zeo/proto.go

@@ -35,7 +35,6 @@ import (
 
 	"lab.nexedi.com/kirr/go123/mem"
 	"lab.nexedi.com/kirr/neo/go/zodb"
-	"lab.nexedi.com/kirr/neo/go/zodb/internal/pickletools"
 )
 
 // msg represents 1 message.
@@ -315,7 +314,7 @@ func (e encoding) xuint64Unpack(xv interface{}) (uint64, bool) {
 
 	case 'Z':
 		// pickle: str|bytes
-		v, err := pickletools.Xstrbytes8(xv)
+		v, err := zodbpickle.Unpack64(xv)
 		if err != nil {
 			return 0, false
 		}