Add cimfs differ and snapshotter

Details about CimFs project are discussed in #8346

Signed-off-by: Amit Barve <ambarve@microsoft.com>

vendor/github.com/Microsoft/hcsshim/computestorage/attach.go

@@ -38,3 +38,31 @@ func AttachLayerStorageFilter(ctx context.Context, layerPath string, layerData L
 	}
 	return nil
 }
+
+// AttachOverlayFilter sets up a filter of the given type on a writable container layer.  Currently the only
+// supported filter types are WCIFS & UnionFS (defined in internal/hcs/schema2/layer.go)
+//
+// `volumePath` is volume path at which writable layer is mounted. If the
+// path does not end in a `\` the platform will append it automatically.
+//
+// `layerData` is the parent read-only layer data.
+func AttachOverlayFilter(ctx context.Context, volumePath string, layerData LayerData) (err error) {
+	title := "hcsshim::AttachOverlayFilter"
+	ctx, span := oc.StartSpan(ctx, title) //nolint:ineffassign,staticcheck
+	defer span.End()
+	defer func() { oc.SetSpanStatus(span, err) }()
+	span.AddAttributes(
+		trace.StringAttribute("volumePath", volumePath),
+	)
+
+	bytes, err := json.Marshal(layerData)
+	if err != nil {
+		return err
+	}
+
+	err = hcsAttachOverlayFilter(volumePath, string(bytes))
+	if err != nil {
+		return errors.Wrap(err, "failed to attach overlay filter")
+	}
+	return nil
+}

vendor/github.com/Microsoft/hcsshim/computestorage/detach.go

@@ -4,7 +4,9 @@ package computestorage
 
 import (
 	"context"
+	"encoding/json"
 
+	hcsschema "github.com/Microsoft/hcsshim/internal/hcs/schema2"
 	"github.com/Microsoft/hcsshim/internal/oc"
 	"github.com/pkg/errors"
 	"go.opencensus.io/trace"
@@ -26,3 +28,27 @@ func DetachLayerStorageFilter(ctx context.Context, layerPath string) (err error)
 	}
 	return nil
 }
+
+// DetachOverlayFilter detaches the filter on a writable container layer.
+//
+// `volumePath` is a path to writable container volume.
+func DetachOverlayFilter(ctx context.Context, volumePath string, filterType hcsschema.FileSystemFilterType) (err error) {
+	title := "hcsshim::DetachOverlayFilter"
+	ctx, span := oc.StartSpan(ctx, title) //nolint:ineffassign,staticcheck
+	defer span.End()
+	defer func() { oc.SetSpanStatus(span, err) }()
+	span.AddAttributes(trace.StringAttribute("volumePath", volumePath))
+
+	layerData := LayerData{}
+	layerData.FilterType = filterType
+	bytes, err := json.Marshal(layerData)
+	if err != nil {
+		return err
+	}
+
+	err = hcsDetachOverlayFilter(volumePath, string(bytes))
+	if err != nil {
+		return errors.Wrap(err, "failed to detach overlay filter")
+	}
+	return nil
+}

vendor/github.com/Microsoft/hcsshim/computestorage/storage.go

@@ -19,14 +19,17 @@ import (
 //sys hcsFormatWritableLayerVhd(handle windows.Handle) (hr error) = computestorage.HcsFormatWritableLayerVhd?
 //sys hcsGetLayerVhdMountPath(vhdHandle windows.Handle, mountPath **uint16) (hr error) = computestorage.HcsGetLayerVhdMountPath?
 //sys hcsSetupBaseOSVolume(layerPath string, volumePath string, options string) (hr error) = computestorage.HcsSetupBaseOSVolume?
+//sys hcsAttachOverlayFilter(volumePath string, layerData string) (hr error) = computestorage.HcsAttachOverlayFilter?
+//sys hcsDetachOverlayFilter(volumePath string, layerData string) (hr error) = computestorage.HcsDetachOverlayFilter?
 
 type Version = hcsschema.Version
 type Layer = hcsschema.Layer
 
 // LayerData is the data used to describe parent layer information.
 type LayerData struct {
-	SchemaVersion Version `json:"SchemaVersion,omitempty"`
-	Layers        []Layer `json:"Layers,omitempty"`
+	SchemaVersion Version                        `json:"SchemaVersion,omitempty"`
+	Layers        []Layer                        `json:"Layers,omitempty"`
+	FilterType    hcsschema.FileSystemFilterType `json:"FilterType,omitempty"`
 }
 
 // ExportLayerOptions are the set of options that are used with the `computestorage.HcsExportLayer` syscall.

vendor/github.com/Microsoft/hcsshim/computestorage/zsyscall_windows.go

@@ -43,8 +43,10 @@ var (
 	modcomputestorage = windows.NewLazySystemDLL("computestorage.dll")
 
 	procHcsAttachLayerStorageFilter = modcomputestorage.NewProc("HcsAttachLayerStorageFilter")
+	procHcsAttachOverlayFilter      = modcomputestorage.NewProc("HcsAttachOverlayFilter")
 	procHcsDestroyLayer             = modcomputestorage.NewProc("HcsDestroyLayer")
 	procHcsDetachLayerStorageFilter = modcomputestorage.NewProc("HcsDetachLayerStorageFilter")
+	procHcsDetachOverlayFilter      = modcomputestorage.NewProc("HcsDetachOverlayFilter")
 	procHcsExportLayer              = modcomputestorage.NewProc("HcsExportLayer")
 	procHcsFormatWritableLayerVhd   = modcomputestorage.NewProc("HcsFormatWritableLayerVhd")
 	procHcsGetLayerVhdMountPath     = modcomputestorage.NewProc("HcsGetLayerVhdMountPath")
@@ -83,6 +85,35 @@ func _hcsAttachLayerStorageFilter(layerPath *uint16, layerData *uint16) (hr erro
 	return
 }
 
+func hcsAttachOverlayFilter(volumePath string, layerData string) (hr error) {
+	var _p0 *uint16
+	_p0, hr = syscall.UTF16PtrFromString(volumePath)
+	if hr != nil {
+		return
+	}
+	var _p1 *uint16
+	_p1, hr = syscall.UTF16PtrFromString(layerData)
+	if hr != nil {
+		return
+	}
+	return _hcsAttachOverlayFilter(_p0, _p1)
+}
+
+func _hcsAttachOverlayFilter(volumePath *uint16, layerData *uint16) (hr error) {
+	hr = procHcsAttachOverlayFilter.Find()
+	if hr != nil {
+		return
+	}
+	r0, _, _ := syscall.Syscall(procHcsAttachOverlayFilter.Addr(), 2, uintptr(unsafe.Pointer(volumePath)), uintptr(unsafe.Pointer(layerData)), 0)
+	if int32(r0) < 0 {
+		if r0&0x1fff0000 == 0x00070000 {
+			r0 &= 0xffff
+		}
+		hr = syscall.Errno(r0)
+	}
+	return
+}
+
 func hcsDestroyLayer(layerPath string) (hr error) {
 	var _p0 *uint16
 	_p0, hr = syscall.UTF16PtrFromString(layerPath)
@@ -131,6 +162,35 @@ func _hcsDetachLayerStorageFilter(layerPath *uint16) (hr error) {
 	return
 }
 
+func hcsDetachOverlayFilter(volumePath string, layerData string) (hr error) {
+	var _p0 *uint16
+	_p0, hr = syscall.UTF16PtrFromString(volumePath)
+	if hr != nil {
+		return
+	}
+	var _p1 *uint16
+	_p1, hr = syscall.UTF16PtrFromString(layerData)
+	if hr != nil {
+		return
+	}
+	return _hcsDetachOverlayFilter(_p0, _p1)
+}
+
+func _hcsDetachOverlayFilter(volumePath *uint16, layerData *uint16) (hr error) {
+	hr = procHcsDetachOverlayFilter.Find()
+	if hr != nil {
+		return
+	}
+	r0, _, _ := syscall.Syscall(procHcsDetachOverlayFilter.Addr(), 2, uintptr(unsafe.Pointer(volumePath)), uintptr(unsafe.Pointer(layerData)), 0)
+	if int32(r0) < 0 {
+		if r0&0x1fff0000 == 0x00070000 {
+			r0 &= 0xffff
+		}
+		hr = syscall.Errno(r0)
+	}
+	return
+}
+
 func hcsExportLayer(layerPath string, exportFolderPath string, layerData string, options string) (hr error) {
 	var _p0 *uint16
 	_p0, hr = syscall.UTF16PtrFromString(layerPath)