Move stats related function to stats/

This also adds a function to read restore stats and verifies the magic
numbers in the stats files.

Signed-off-by: Adrian Reber <areber@redhat.com>

phaul/client.go

@@ -110,7 +110,7 @@ func (pc *Client) Migrate() error {
 			return err
 		}
 
-		st, err := criuGetDumpStats(imgDir)
+		st, err := stats.CriuGetDumpStats(imgDir)
 		if err != nil {
 			return err
 		}

stats/utils.go

@@ -0,0 +1,54 @@
+package stats
+
+import (
+	"encoding/binary"
+	"errors"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/checkpoint-restore/go-criu/v5/magic"
+	"google.golang.org/protobuf/proto"
+)
+
+func readStatisticsFile(imgDir *os.File, fileName string) (*StatsEntry, error) {
+	buf, err := ioutil.ReadFile(filepath.Join(imgDir.Name(), fileName))
+	if err != nil {
+		return nil, err
+	}
+
+	if binary.LittleEndian.Uint32(buf[magic.PrimaryMagicOffset:magic.SecondaryMagicOffset]) != magic.ImgServiceMagic {
+		return nil, errors.New("Primary magic not found")
+	}
+
+	if binary.LittleEndian.Uint32(buf[magic.SecondaryMagicOffset:magic.SizeOffset]) != magic.StatsMagic {
+		return nil, errors.New("Secondary magic not found")
+	}
+
+	payloadSize := binary.LittleEndian.Uint32(buf[magic.SizeOffset:magic.PayloadOffset])
+
+	st := &StatsEntry{}
+	if err := proto.Unmarshal(buf[magic.PayloadOffset:magic.PayloadOffset+payloadSize], st); err != nil {
+		return nil, err
+	}
+
+	return st, nil
+}
+
+func CriuGetDumpStats(imgDir *os.File) (*DumpStatsEntry, error) {
+	st, err := readStatisticsFile(imgDir, StatsDump)
+	if err != nil {
+		return nil, err
+	}
+
+	return st.GetDump(), nil
+}
+
+func CriuGetRestoreStats(imgDir *os.File) (*RestoreStatsEntry, error) {
+	st, err := readStatisticsFile(imgDir, StatsRestore)
+	if err != nil {
+		return nil, err
+	}
+
+	return st.GetRestore(), nil
+}