fix: handle overlay xattr opaque bit

Current behavior determines if a path is a whiteout if a overlay char
dev is present.

Additionally, also check the extended attrs.

Signed-off-by: Ramkumar Chinchani <rchincha@cisco.com>

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/opencontainers/runc v1.1.8
 	github.com/opencontainers/runtime-spec v1.0.3-0.20210326190908-1c3f411f0417
 	github.com/pkg/errors v0.9.1
+	github.com/pkg/xattr v0.4.9
 	github.com/rootless-containers/proto/go-proto v0.0.0-20230421021042-4cd87ebadd67
 	github.com/stretchr/testify v1.8.4
 	github.com/urfave/cli v1.22.12

go.sum

@@ -72,6 +72,8 @@ github.com/opencontainers/runtime-spec v1.0.3-0.20210326190908-1c3f411f0417/go.m
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/xattr v0.4.9 h1:5883YPCtkSd8LFbs13nXplj9g9tlrwoJRjgpgMu1/fE=
+github.com/pkg/xattr v0.4.9/go.mod h1:di8WF84zAKk8jzR1UBTEWh9AUlIZZ7M/JNt8e9B6ktU=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rogpeppe/fastuuid v1.1.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6LYCDYWNEvQ=
@@ -123,6 +125,7 @@ golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220408201424-a24fb2fb8a0f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
 golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

oci/layer/generate.go

@@ -88,7 +88,7 @@ func GenerateLayer(path string, deltas []mtree.InodeDelta, opt *RepackOptions) (
 						return errors.Wrapf(err, "couldn't determine overlay whiteout for %s", fullPath)
 					}
 
-					whiteout, err := isOverlayWhiteout(fi)
+					whiteout, err := isOverlayWhiteout(fi, fullPath)
 					if err != nil {
 						return err
 					}
@@ -166,7 +166,7 @@ func GenerateInsertLayer(root string, target string, opaque bool, opt *RepackOpt
 			}
 
 			pathInTar := path.Join(target, curPath[len(root):])
-			whiteout, err := isOverlayWhiteout(info)
+			whiteout, err := isOverlayWhiteout(info, filepath.Join(curPath, info.Name()))
 			if err != nil {
 				return err
 			}

oci/layer/utils.go

@@ -19,6 +19,7 @@ package layer
 
 import (
 	"archive/tar"
+	"fmt"
 	"os"
 	"path/filepath"
 	"syscall"
@@ -27,6 +28,7 @@ import (
 	rspec "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/opencontainers/umoci/pkg/idtools"
 	"github.com/pkg/errors"
+	"github.com/pkg/xattr"
 	rootlesscontainers "github.com/rootless-containers/proto/go-proto"
 	"golang.org/x/sys/unix"
 	"google.golang.org/protobuf/proto"
@@ -230,7 +232,7 @@ func InnerErrno(err error) error {
 
 // isOverlayWhiteout returns true if the FileInfo represents an overlayfs style
 // whiteout (i.e. mknod c 0 0) and false otherwise.
-func isOverlayWhiteout(info os.FileInfo) (bool, error) {
+func isOverlayWhiteout(info os.FileInfo, path string) (bool, error) {
 	var major, minor uint32
 	switch stat := info.Sys().(type) {
 	case *unix.Stat_t:
@@ -243,6 +245,17 @@ func isOverlayWhiteout(info os.FileInfo) (bool, error) {
 		return false, errors.Errorf("[internal error] unknown stat info type %T", info.Sys())
 	}
 
-	return major == 0 && minor == 0 &&
-		info.Mode()&os.ModeCharDevice != 0, nil
+	if major == 0 && minor == 0 &&
+		info.Mode()&os.ModeCharDevice != 0 {
+		return true, nil
+	}
+
+	attr, err := xattr.LGet("user.overlay.opaque", path)
+	if err != nil && !errors.Is(err, os.ErrNotExist) {
+		return false, errors.Errorf("[internal error] failed to get extended attrs for %s, err:%v", path, err)
+	}
+
+	fmt.Printf("ATTR=%+v\n", attr)
+
+	return false, nil
 }

vendor/modules.txt

@@ -63,6 +63,9 @@ github.com/opencontainers/runtime-spec/specs-go
 # github.com/pkg/errors v0.9.1
 ## explicit
 github.com/pkg/errors
+# github.com/pkg/xattr v0.4.9
+## explicit; go 1.14
+github.com/pkg/xattr
 # github.com/pmezard/go-difflib v1.0.0
 ## explicit
 github.com/pmezard/go-difflib/difflib