Add preserve ownership option for copy to container

Signed-off-by: Derek McGowan <derek@mcg.dev>

Author: dmcgowan

api/next.txtpb

@@ -965,6 +965,13 @@ file: {
       type: TYPE_BOOL
       json_name: "noWalk"
     }
+    field: {
+      name: "preserve_ownership"
+      number: 4
+      label: LABEL_OPTIONAL
+      type: TYPE_BOOL
+      json_name: "preserveOwnership"
+    }
   }
   options: {
     go_package: "github.com/containerd/nerdbox/api/types/transfer/v1;transfer"
@@ -973,7 +980,7 @@ file: {
     location: {
       span: 16
       span: 0
-      span: 33
+      span: 38
       span: 1
     }
     location: {
@@ -1007,7 +1014,7 @@ file: {
       path: 0
       span: 25
       span: 0
-      span: 33
+      span: 38
       span: 1
       leading_comments: " ContainerFilesystem represents a path within a running container's\n filesystem. It acts as either a source or destination in a transfer\n operation, identifying the container and path for archive operations.\n"
     }
@@ -1137,6 +1144,46 @@ file: {
       span: 23
       span: 24
     }
+    location: {
+      path: 4
+      path: 0
+      path: 2
+      path: 3
+      span: 37
+      span: 8
+      span: 36
+      leading_comments: " When true, preserve the UID/GID from tar headers when extracting\n files. When false, extracted files are owned by the extracting\n process.\n"
+    }
+    location: {
+      path: 4
+      path: 0
+      path: 2
+      path: 3
+      path: 5
+      span: 37
+      span: 8
+      span: 12
+    }
+    location: {
+      path: 4
+      path: 0
+      path: 2
+      path: 3
+      path: 1
+      span: 37
+      span: 13
+      span: 31
+    }
+    location: {
+      path: 4
+      path: 0
+      path: 2
+      path: 3
+      path: 3
+      span: 37
+      span: 34
+      span: 35
+    }
   }
   syntax: "proto3"
   buf_extension: {

api/proto/nerdbox/types/transfer/v1/filesystem.proto

@@ -31,4 +31,9 @@ message ContainerFilesystem {
 	// itself without walking into its contents. This is useful for
 	// stat-like operations where only the directory's metadata is needed.
 	bool no_walk = 3;
+
+	// When true, preserve the UID/GID from tar headers when extracting
+	// files. When false, extracted files are owned by the extracting
+	// process.
+	bool preserve_ownership = 4;
 }

api/types/transfer/v1/filesystem.pb.go

@@ -63,7 +63,7 @@ func (t *containerFSTransferrer) Transfer(ctx context.Context, src, dst any, opt
 		}
 		rootfs := filepath.Join(t.bundleDir, d.ContainerID, "rootfs")
 		r := s.Reader(ctx)
-		return readPath(r, rootfs, d.Path, s.MediaType)
+		return readPath(r, rootfs, d.Path, s.MediaType, d.PreserveOwnership)
 	}
 
 	return errdefs.ErrNotImplemented
@@ -150,8 +150,9 @@ func writeTarEntry(tw *tar.Writer, filePath string, fi os.FileInfo, name string)
 }
 
 // readPath reads a tar archive from r and extracts it to the given path
-// within rootfs.
-func readPath(r io.Reader, rootfs, path, mediaType string) error {
+// within rootfs. When preserveOwnership is true, extracted files have
+// their UID/GID set from the tar headers.
+func readPath(r io.Reader, rootfs, path, mediaType string, preserveOwnership bool) error {
 	if mediaType != mediaTypeTar {
 		return fmt.Errorf("unsupported media type %q: %w", mediaType, errdefs.ErrNotImplemented)
 	}
@@ -175,13 +176,13 @@ func readPath(r io.Reader, rootfs, path, mediaType string) error {
 			return fmt.Errorf("tar entry %q would escape destination", header.Name)
 		}
 
-		if err := extractTarEntry(target, header, tr); err != nil {
+		if err := extractTarEntry(target, header, tr, preserveOwnership); err != nil {
 			return err
 		}
 	}
 }
 
-func extractTarEntry(target string, header *tar.Header, r io.Reader) error {
+func extractTarEntry(target string, header *tar.Header, r io.Reader, preserveOwnership bool) error {
 	switch header.Typeflag {
 	case tar.TypeDir:
 		if err := os.MkdirAll(target, os.FileMode(header.Mode)); err != nil {
@@ -217,5 +218,12 @@ func extractTarEntry(target string, header *tar.Header, r io.Reader) error {
 			return err
 		}
 	}
+
+	if preserveOwnership {
+		if err := os.Lchown(target, header.Uid, header.Gid); err != nil {
+			return fmt.Errorf("failed to chown %s: %w", target, err)
+		}
+	}
+
 	return nil
 }

internal/transfer/containerfs.go

@@ -39,17 +39,19 @@ func init() {
 // filesystem. It acts as either a source or destination in a transfer
 // operation, identifying the container and path for archive operations.
 type ContainerFilesystem struct {
-	ContainerID string
-	Path        string
-	NoWalk   bool
+	ContainerID       string
+	Path              string
+	NoWalk            bool
+	PreserveOwnership bool
 }
 
 // MarshalAny marshals the ContainerFilesystem to a typeurl.Any.
 func (cf *ContainerFilesystem) MarshalAny(ctx context.Context, sm streaming.StreamCreator) (typeurl.Any, error) {
 	return typeurl.MarshalAny(&transferpb.ContainerFilesystem{
-		ContainerID: cf.ContainerID,
-		Path:        cf.Path,
-		NoWalk:   cf.NoWalk,
+		ContainerID:       cf.ContainerID,
+		Path:              cf.Path,
+		NoWalk:            cf.NoWalk,
+		PreserveOwnership: cf.PreserveOwnership,
 	})
 }
 
@@ -62,6 +64,7 @@ func (cf *ContainerFilesystem) UnmarshalAny(ctx context.Context, sg streaming.St
 	cf.ContainerID = p.ContainerID
 	cf.Path = p.Path
 	cf.NoWalk = p.NoWalk
+	cf.PreserveOwnership = p.PreserveOwnership
 	return nil
 }