cgroups: reuse version check from c/common

[NO NEW TESTS NEEDED]

Signed-off-by: Lokesh Mandvekar <lsm5@redhat.com>
Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

info.go

@@ -12,6 +12,7 @@ import (
 	internalUtil "github.com/containers/buildah/internal/util"
 	putil "github.com/containers/buildah/pkg/util"
 	"github.com/containers/buildah/util"
+	"github.com/containers/common/pkg/cgroups"
 	"github.com/containers/storage"
 	"github.com/containers/storage/pkg/system"
 	"github.com/containers/storage/pkg/unshare"
@@ -50,7 +51,7 @@ func hostInfo() map[string]interface{} {
 	info["cpus"] = runtime.NumCPU()
 	info["rootless"] = unshare.IsRootless()
 
-	unified, err := util.IsCgroup2UnifiedMode()
+	unified, err := cgroups.IsCgroup2UnifiedMode()
 	if err != nil {
 		logrus.Error(err, "err reading cgroups mode")
 	}

util/util.go

@@ -9,7 +9,6 @@ import (
 	"path/filepath"
 	"sort"
 	"strings"
-	"sync"
 	"syscall"
 
 	"github.com/containers/buildah/define"
@@ -376,12 +375,6 @@ func TruncateString(str string, to int) string {
 	return newStr
 }
 
-var (
-	isUnifiedOnce sync.Once
-	isUnified     bool
-	isUnifiedErr  error
-)
-
 // fileExistsAndNotADir - Check to see if a file exists
 // and that it is not a directory.
 func fileExistsAndNotADir(path string) (bool, error) {

util/util_linux.go

@@ -1,20 +0,0 @@
-package util
-
-import (
-	"syscall"
-
-	"golang.org/x/sys/unix"
-)
-
-// IsCgroup2UnifiedMode returns whether we are running in cgroup 2 cgroup2 mode.
-func IsCgroup2UnifiedMode() (bool, error) {
-	isUnifiedOnce.Do(func() {
-		var st syscall.Statfs_t
-		if err := syscall.Statfs("/sys/fs/cgroup", &st); err != nil {
-			isUnified, isUnifiedErr = false, err
-		} else {
-			isUnified, isUnifiedErr = st.Type == unix.CGROUP2_SUPER_MAGIC, nil
-		}
-	})
-	return isUnified, isUnifiedErr
-}