support symlinks for archive creation (#559)

* support symlinks for archive creation

* fix transporting signatures in overwrite mode

pkg/contexts/ocm/cpi/view.go

@@ -1072,10 +1072,12 @@ func (c *componentVersionAccessView) SetResource(meta *internal.ResourceMeta, ac
 
 		if old != nil {
 			eq := res.Equivalent(old)
-			if !eq.IsLocalHashEqual() && !opts.IsModifyResource() && c.impl.IsPersistent() {
-				return fmt.Errorf("resource would invalidate signature")
+			if !eq.IsLocalHashEqual() && c.impl.IsPersistent() {
+				if !opts.IsModifyResource() {
+					return fmt.Errorf("resource would invalidate signature")
+				}
+				cd.Signatures = nil
 			}
-			cd.Signatures = nil
 		}
 
 		if old == nil {

pkg/utils/tarutils/pack.go

@@ -135,10 +135,12 @@ func addFileToTar(fs vfs.FileSystem, tw *tar.Writer, path string, realPath strin
 			if err != nil {
 				return err
 			}
-			relPath, err := vfs.Rel(fs, realPath, subFilePath)
-			if err != nil {
-				return fmt.Errorf("unable to calculate relative path for %s: %w", subFilePath, err)
-			}
+			/*
+				relPath, err := vfs.Rel(fs, realPath, subFilePath)
+				if err != nil {
+					return fmt.Errorf("unable to calculate relative path for %s: %w", subFilePath, err)
+				}*/
+			relPath := vfs.Base(fs, subFilePath)
 			err = addFileToTar(fs, tw, vfs.Join(fs, path, relPath), subFilePath, opts)
 			if err != nil {
 				return fmt.Errorf("failed to tar the input from %q: %w", subFilePath, err)
@@ -167,14 +169,22 @@ func addFileToTar(fs vfs.FileSystem, tw *tar.Writer, path string, realPath strin
 		return nil
 	case header.Typeflag == tar.TypeSymlink:
 		if !opts.FollowSymlinks {
-			// log.Info(fmt.Sprintf("symlink found in %q but symlinks are not followed", path))
+			link, err := fs.Readlink(realPath)
+			if err != nil {
+				return fmt.Errorf("cannot read symlink %s: %w", realPath, err)
+			}
+			header.Linkname = link
+			if err := tw.WriteHeader(header); err != nil {
+				return fmt.Errorf("unable to write header for %q: %w", path, err)
+			}
 			return nil
+		} else {
+			effPath, err := vfs.EvalSymlinks(fs, realPath)
+			if err != nil {
+				return fmt.Errorf("unable to follow symlink %s: %w", realPath, err)
+			}
+			return addFileToTar(fs, tw, path, effPath, opts)
 		}
-		effPath, err := vfs.EvalSymlinks(fs, realPath)
-		if err != nil {
-			return fmt.Errorf("unable to follow symlink %s: %w", realPath, err)
-		}
-		return addFileToTar(fs, tw, path, effPath, opts)
 	default:
 		return fmt.Errorf("unsupported file type %s in %s", info.Mode().String(), path)
 	}

pkg/utils/tarutils/pack_test.go

@@ -0,0 +1,47 @@
+// SPDX-FileCopyrightText: 2022 SAP SE or an SAP affiliate company and Open Component Model contributors.
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package tarutils_test
+
+import (
+	"os"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+	. "github.com/open-component-model/ocm/pkg/testutils"
+
+	"github.com/mandelsoft/vfs/pkg/osfs"
+
+	"github.com/open-component-model/ocm/pkg/utils/tarutils"
+)
+
+var _ = Describe("tar utils mapping", func() {
+	It("creates config data", func() {
+		file := Must(os.CreateTemp("", "tar*"))
+		defer func() {
+			file.Close()
+			os.Remove(file.Name())
+		}()
+
+		MustBeSuccessful(tarutils.PackFsIntoTar(osfs.OsFs, "testdata", file, tarutils.TarFileSystemOptions{}))
+		file.Close()
+
+		list := Must(tarutils.ListArchiveContent(file.Name()))
+		Expect(list).To(HaveExactElements("dir", "dir/dirlink", "dir/link", "dir/regular", "dir/subdir", "dir/subdir/file", "dir2", "dir2/file2", "file"))
+	})
+
+	It("creates config data", func() {
+		file := Must(os.CreateTemp("", "tar*"))
+		defer func() {
+			file.Close()
+			// os.Remove(file.Name())
+		}()
+
+		MustBeSuccessful(tarutils.PackFsIntoTar(osfs.OsFs, "testdata", file, tarutils.TarFileSystemOptions{FollowSymlinks: true}))
+		file.Close()
+
+		list := Must(tarutils.ListArchiveContent(file.Name()))
+		Expect(list).To(ConsistOf("dir", "dir/dirlink", "dir/link", "dir/regular", "dir/subdir", "dir/subdir/file", "dir2", "dir2/file2", "file", "dir/dirlink/file2"))
+	})
+})

pkg/utils/tarutils/suite_test.go

@@ -0,0 +1,17 @@
+// SPDX-FileCopyrightText: 2022 SAP SE or an SAP affiliate company and Open Component Model contributors.
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package tarutils_test
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestConfig(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Tar Utils Test Suite")
+}

pkg/utils/tarutils/testdata/dir/dirlink

@@ -0,0 +1 @@
+../dir2

pkg/utils/tarutils/testdata/dir/link

@@ -0,0 +1 @@
+../file