wclayer: Work around Windows bug when expanding sandbox size

internal/wclayer/expandscratchsize.go

@@ -1,7 +1,13 @@
 package wclayer
 
 import (
+	"os"
+	"path/filepath"
+	"syscall"
+	"unsafe"
+
 	"github.com/Microsoft/hcsshim/internal/hcserror"
+	"github.com/Microsoft/hcsshim/osversion"
 	"github.com/sirupsen/logrus"
 )
 
@@ -26,5 +32,114 @@ func ExpandScratchSize(path string, size uint64) (err error) {
 	if err != nil {
 		return hcserror.New(err, title+" - failed", "")
 	}
+
+	// Manually expand the volume now in order to work around bugs in 19H1 and
+	// prerelease versions of Vb. Remove once this is fixed in Windows.
+	if build := osversion.Get().Build; build >= osversion.V19H1 && build < 19020 {
+		err = expandSandboxVolume(path)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+type virtualStorageType struct {
+	DeviceID uint32
+	VendorID [16]byte
+}
+
+type openVersion2 struct {
+	GetInfoOnly    int32    // bool but 4-byte aligned
+	ReadOnly       int32    // bool but 4-byte aligned
+	ResiliencyGUID [16]byte // GUID
+}
+
+type openVirtualDiskParameters struct {
+	Version  uint32 // Must always be set to 2
+	Version2 openVersion2
+}
+
+func attachVhd(path string) (syscall.Handle, error) {
+	var (
+		defaultType virtualStorageType
+		handle      syscall.Handle
+	)
+	parameters := openVirtualDiskParameters{Version: 2}
+	err := openVirtualDisk(
+		&defaultType,
+		path,
+		0,
+		0,
+		&parameters,
+		&handle)
+	if err != nil {
+		return 0, &os.PathError{Op: "OpenVirtualDisk", Path: path, Err: err}
+	}
+	err = attachVirtualDisk(handle, 0, 0, 0, 0, 0)
+	if err != nil {
+		syscall.Close(handle)
+		return 0, &os.PathError{Op: "AttachVirtualDisk", Path: path, Err: err}
+	}
+	return handle, nil
+}
+
+func expandSandboxVolume(path string) error {
+	// Mount the sandbox VHD temporarily.
+	vhdPath := filepath.Join(path, "sandbox.vhdx")
+	vhd, err := attachVhd(vhdPath)
+	if err != nil {
+		return &os.PathError{Op: "OpenVirtualDisk", Path: vhdPath, Err: err}
+	}
+	defer syscall.Close(vhd)
+
+	// Open the volume.
+	volumePath, err := GetLayerMountPath(path)
+	if err != nil {
+		return err
+	}
+	if volumePath[len(volumePath)-1] == '\\' {
+		volumePath = volumePath[:len(volumePath)-1]
+	}
+	volume, err := os.OpenFile(volumePath, os.O_RDWR, 0)
+	if err != nil {
+		return err
+	}
+	defer volume.Close()
+
+	// Get the volume's underlying partition size in NTFS clusters.
+	var (
+		partitionSize int64
+		bytes         uint32
+	)
+	const _IOCTL_DISK_GET_LENGTH_INFO = 0x0007405C
+	err = syscall.DeviceIoControl(syscall.Handle(volume.Fd()), _IOCTL_DISK_GET_LENGTH_INFO, nil, 0, (*byte)(unsafe.Pointer(&partitionSize)), 8, &bytes, nil)
+	if err != nil {
+		return &os.PathError{Op: "IOCTL_DISK_GET_LENGTH_INFO", Path: volume.Name(), Err: err}
+	}
+	const (
+		clusterSize = 4096
+		sectorSize  = 512
+	)
+	targetClusters := partitionSize / clusterSize
+
+	// Get the volume's current size in NTFS clusters.
+	var volumeSize int64
+	err = getDiskFreeSpaceEx(volume.Name()+"\\", nil, &volumeSize, nil)
+	if err != nil {
+		return &os.PathError{Op: "GetDiskFreeSpaceEx", Path: volume.Name(), Err: err}
+	}
+	volumeClusters := volumeSize / clusterSize
+
+	// Only resize the volume if there is space to grow, otherwise this will
+	// fail with invalid parameter. NTFS reserves one cluster.
+	if volumeClusters+1 < targetClusters {
+		targetSectors := targetClusters * (clusterSize / sectorSize)
+		const _FSCTL_EXTEND_VOLUME = 0x000900F0
+		err = syscall.DeviceIoControl(syscall.Handle(volume.Fd()), _FSCTL_EXTEND_VOLUME, (*byte)(unsafe.Pointer(&targetSectors)), 8, nil, 0, &bytes, nil)
+		if err != nil {
+			return &os.PathError{Op: "FSCTL_EXTEND_VOLUME", Path: volume.Name(), Err: err}
+		}
+	}
 	return nil
 }

internal/wclayer/wclayer.go

@@ -24,4 +24,9 @@ import "github.com/Microsoft/go-winio/pkg/guid"
 
 //sys grantVmAccess(vmid string, filepath string) (hr error) = vmcompute.GrantVmAccess?
 
+//sys openVirtualDisk(virtualStorageType *virtualStorageType, path string, virtualDiskAccessMask uint32, flags uint32, parameters *openVirtualDiskParameters, handle *syscall.Handle) (err error) [failretval != 0] = virtdisk.OpenVirtualDisk
+//sys attachVirtualDisk(handle syscall.Handle, sd uintptr, flags uint32, providerFlags uint32, params uintptr, overlapped uintptr) (err error) [failretval != 0] = virtdisk.AttachVirtualDisk
+
+//sys getDiskFreeSpaceEx(directoryName string, freeBytesAvailableToCaller *int64, totalNumberOfBytes *int64, totalNumberOfFreeBytes *int64) (err error) = GetDiskFreeSpaceExW
+
 type _guid = guid.GUID