Vendor opengcs and hcsshim

Signed-off-by: Darren Stahl <darst@microsoft.com>

vendor/github.com/Microsoft/opengcs/client/config.go

@@ -0,0 +1,274 @@
+// +build windows
+
+package client
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/Microsoft/hcsshim"
+	"github.com/sirupsen/logrus"
+)
+
+// Mode is the operational mode, both requested, and actual after verification
+type Mode uint
+
+const (
+	// Constants for the actual mode after validation
+
+	// ModeActualError means an error has occurred during validation
+	ModeActualError = iota
+	// ModeActualVhdx means that we are going to use VHDX boot after validation
+	ModeActualVhdx
+	// ModeActualKernelInitrd means that we are going to use kernel+initrd for boot after validation
+	ModeActualKernelInitrd
+
+	// Constants for the requested mode
+
+	// ModeRequestAuto means auto-select the boot mode for a utility VM
+	ModeRequestAuto = iota // VHDX will be priority over kernel+initrd
+	// ModeRequestVhdx means request VHDX boot if possible
+	ModeRequestVhdx
+	// ModeRequestKernelInitrd means request Kernel+initrd boot if possible
+	ModeRequestKernelInitrd
+
+	// defaultUvmTimeoutSeconds is the default time to wait for utility VM operations
+	defaultUvmTimeoutSeconds = 5 * 60
+
+	// DefaultVhdxSizeGB is the size of the default sandbox & scratch in GB
+	DefaultVhdxSizeGB = 20
+
+	// defaultVhdxBlockSizeMB is the block-size for the sandbox/scratch VHDx's this package can create.
+	defaultVhdxBlockSizeMB = 1
+)
+
+// Config is the structure used to configuring a utility VM. There are two ways
+// of starting. Either supply a VHD, or a Kernel+Initrd. For the latter, both
+// must be supplied, and both must be in the same directory.
+//
+// VHD is the priority.
+type Config struct {
+	Options                                        // Configuration options
+	Name               string                      // Name of the utility VM
+	RequestedMode      Mode                        // What mode is preferred when validating
+	ActualMode         Mode                        // What mode was obtained during validation
+	UvmTimeoutSeconds  int                         // How long to wait for the utility VM to respond in seconds
+	Uvm                hcsshim.Container           // The actual container
+	MappedVirtualDisks []hcsshim.MappedVirtualDisk // Data-disks to be attached
+}
+
+// Options is the structure used by a client to define configurable options for a utility VM.
+type Options struct {
+	KirdPath       string // Path to where kernel/initrd are found (defaults to %PROGRAMFILES%\Linux Containers)
+	KernelFile     string // Kernel for Utility VM (embedded in a UEFI bootloader) - does NOT include full path, just filename
+	InitrdFile     string // Initrd image for Utility VM - does NOT include full path, just filename
+	Vhdx           string // VHD for booting the utility VM - is a full path
+	TimeoutSeconds int    // Requested time for the utility VM to respond in seconds (may be over-ridden by environment)
+	BootParameters string // Additional boot parameters for initrd booting (not VHDx)
+}
+
+// ParseOptions parses a set of K-V pairs into options used by opengcs. Note
+// for consistency with the LCOW graphdriver in docker, we keep the same
+// convention of an `lcow.` prefix.
+func ParseOptions(options []string) (Options, error) {
+	rOpts := Options{TimeoutSeconds: 0}
+	for _, v := range options {
+		opt := strings.SplitN(v, "=", 2)
+		if len(opt) == 2 {
+			switch strings.ToLower(opt[0]) {
+			case "lcow.kirdpath":
+				rOpts.KirdPath = opt[1]
+			case "lcow.kernel":
+				rOpts.KernelFile = opt[1]
+			case "lcow.initrd":
+				rOpts.InitrdFile = opt[1]
+			case "lcow.vhdx":
+				rOpts.Vhdx = opt[1]
+			case "lcow.bootparameters":
+				rOpts.BootParameters = opt[1]
+			case "lcow.timeout":
+				var err error
+				if rOpts.TimeoutSeconds, err = strconv.Atoi(opt[1]); err != nil {
+					return rOpts, fmt.Errorf("opengcstimeoutsecs option could not be interpreted as an integer")
+				}
+				if rOpts.TimeoutSeconds < 0 {
+					return rOpts, fmt.Errorf("opengcstimeoutsecs option cannot be negative")
+				}
+			}
+		}
+	}
+
+	// Set default values if not supplied
+	if rOpts.KirdPath == "" {
+		rOpts.KirdPath = filepath.Join(os.Getenv("ProgramFiles"), "Linux Containers")
+	}
+	if rOpts.Vhdx == "" {
+		rOpts.Vhdx = filepath.Join(rOpts.KirdPath, `uvm.vhdx`)
+	}
+	if rOpts.KernelFile == "" {
+		rOpts.KernelFile = `bootx64.efi`
+	}
+	if rOpts.InitrdFile == "" {
+		rOpts.InitrdFile = `initrd.img`
+	}
+
+	return rOpts, nil
+}
+
+// GenerateDefault generates a default config from a set of options
+// If baseDir is not supplied, defaults to $env:ProgramFiles\Linux Containers
+func (config *Config) GenerateDefault(options []string) error {
+	// Parse the options that the user supplied.
+	var err error
+	config.Options, err = ParseOptions(options)
+	if err != nil {
+		return err
+	}
+
+	// Get the timeout from the environment
+	envTimeoutSeconds := 0
+	envTimeout := os.Getenv("OPENGCS_UVM_TIMEOUT_SECONDS")
+	if len(envTimeout) > 0 {
+		var err error
+		if envTimeoutSeconds, err = strconv.Atoi(envTimeout); err != nil {
+			return fmt.Errorf("OPENGCS_UVM_TIMEOUT_SECONDS could not be interpreted as an integer")
+		}
+		if envTimeoutSeconds < 0 {
+			return fmt.Errorf("OPENGCS_UVM_TIMEOUT_SECONDS cannot be negative")
+		}
+	}
+
+	// Priority to the requested timeout from the options.
+	if config.TimeoutSeconds != 0 {
+		config.UvmTimeoutSeconds = config.TimeoutSeconds
+		return nil
+	}
+
+	// Next priority, the environment
+	if envTimeoutSeconds != 0 {
+		config.UvmTimeoutSeconds = envTimeoutSeconds
+		return nil
+	}
+
+	// Last priority is the default timeout
+	config.UvmTimeoutSeconds = defaultUvmTimeoutSeconds
+
+	// Set the default requested mode
+	config.RequestedMode = ModeRequestAuto
+
+	return nil
+}
+
+// Validate validates a Config structure for starting a utility VM.
+func (config *Config) Validate() error {
+	config.ActualMode = ModeActualError
+
+	if config.RequestedMode == ModeRequestVhdx && config.Vhdx == "" {
+		return fmt.Errorf("VHDx mode must supply a VHDx")
+	}
+	if config.RequestedMode == ModeRequestKernelInitrd && (config.KernelFile == "" || config.InitrdFile == "") {
+		return fmt.Errorf("kernel+initrd mode must supply both kernel and initrd")
+	}
+
+	// Validate that if VHDX requested or auto, it exists.
+	if config.RequestedMode == ModeRequestAuto || config.RequestedMode == ModeRequestVhdx {
+		if _, err := os.Stat(config.Vhdx); os.IsNotExist(err) {
+			if config.RequestedMode == ModeRequestVhdx {
+				return fmt.Errorf("VHDx '%s' not found", config.Vhdx)
+			}
+		} else {
+			config.ActualMode = ModeActualVhdx
+
+			// Can't specify boot parameters with VHDx
+			if config.BootParameters != "" {
+				return fmt.Errorf("Boot parameters cannot be specified in VHDx mode")
+			}
+			return nil
+		}
+	}
+
+	// So must be kernel+initrd, or auto where we fallback as the VHDX doesn't exist
+	if config.InitrdFile == "" || config.KernelFile == "" {
+		if config.RequestedMode == ModeRequestKernelInitrd {
+			return fmt.Errorf("initrd and kernel options must be supplied")
+		}
+		return fmt.Errorf("opengcs: configuration is invalid")
+	}
+
+	if _, err := os.Stat(filepath.Join(config.KirdPath, config.KernelFile)); os.IsNotExist(err) {
+		return fmt.Errorf("kernel '%s' not found", filepath.Join(config.KirdPath, config.KernelFile))
+	}
+	if _, err := os.Stat(filepath.Join(config.KirdPath, config.InitrdFile)); os.IsNotExist(err) {
+		return fmt.Errorf("initrd '%s' not found", filepath.Join(config.KirdPath, config.InitrdFile))
+	}
+
+	config.ActualMode = ModeActualKernelInitrd
+
+	// Ensure all the MappedVirtualDisks exist on the host
+	for _, mvd := range config.MappedVirtualDisks {
+		if _, err := os.Stat(mvd.HostPath); err != nil {
+			return fmt.Errorf("mapped virtual disk '%s' not found", mvd.HostPath)
+		}
+		if mvd.ContainerPath == "" {
+			return fmt.Errorf("mapped virtual disk '%s' requested without a container path", mvd.HostPath)
+		}
+	}
+
+	return nil
+}
+
+// StartUtilityVM creates and starts a utility VM from a configuration.
+func (config *Config) StartUtilityVM() error {
+	logrus.Debugf("opengcs: StartUtilityVM: %+v", config)
+
+	if err := config.Validate(); err != nil {
+		return err
+	}
+
+	configuration := &hcsshim.ContainerConfig{
+		HvPartition:                 true,
+		Name:                        config.Name,
+		SystemType:                  "container",
+		ContainerType:               "linux",
+		TerminateOnLastHandleClosed: true,
+		MappedVirtualDisks:          config.MappedVirtualDisks,
+	}
+
+	if config.ActualMode == ModeActualVhdx {
+		configuration.HvRuntime = &hcsshim.HvRuntime{
+			ImagePath:          config.Vhdx,
+			BootSource:         "Vhd",
+			WritableBootSource: true,
+		}
+	} else {
+		configuration.HvRuntime = &hcsshim.HvRuntime{
+			ImagePath:           config.KirdPath,
+			LinuxInitrdFile:     config.InitrdFile,
+			LinuxKernelFile:     config.KernelFile,
+			LinuxBootParameters: config.BootParameters,
+		}
+	}
+
+	configurationS, _ := json.Marshal(configuration)
+	logrus.Debugf("opengcs: StartUtilityVM: calling HCS with '%s'", string(configurationS))
+	uvm, err := hcsshim.CreateContainer(config.Name, configuration)
+	if err != nil {
+		return err
+	}
+	logrus.Debugf("opengcs: StartUtilityVM: uvm created, starting...")
+	err = uvm.Start()
+	if err != nil {
+		logrus.Debugf("opengcs: StartUtilityVM: uvm failed to start: %s", err)
+		// Make sure we don't leave it laying around as it's been created in HCS
+		uvm.Terminate()
+		return err
+	}
+
+	config.Uvm = uvm
+	logrus.Debugf("opengcs StartUtilityVM: uvm %s is running", config.Name)
+	return nil
+}

vendor/github.com/Microsoft/opengcs/client/createext4vhdx.go

@@ -0,0 +1,165 @@
+// +build windows
+
+package client
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"strings"
+	"time"
+
+	winio "github.com/Microsoft/go-winio/vhd"
+	//	"github.com/Microsoft/hcsshim"
+	"github.com/sirupsen/logrus"
+)
+
+// dismount is a simple utility function wrapping a conditional HotRemove. It would
+// have been easier if you could cancel a deferred function, but this works just
+// as well.
+func (config *Config) dismount(file string) error {
+	logrus.Debugf("opengcs: CreateExt4Vhdx: hot-remove of %s", file)
+	err := config.HotRemoveVhd(file)
+	if err != nil {
+		logrus.Warnf("failed to hot-remove: %s", err)
+	}
+	return err
+}
+
+// CreateExt4Vhdx does what it says on the tin. It is the responsibility of the caller to synchronise
+// simultaneous attempts to create the cache file.
+func (config *Config) CreateExt4Vhdx(destFile string, sizeGB uint32, cacheFile string) error {
+	// Smallest we can accept is the default sandbox size as we can't size down, only expand.
+	if sizeGB < DefaultVhdxSizeGB {
+		sizeGB = DefaultVhdxSizeGB
+	}
+
+	logrus.Debugf("opengcs: CreateExt4Vhdx: %s size:%dGB cache:%s", destFile, sizeGB, cacheFile)
+
+	// Retrieve from cache if the default size and already on disk
+	if cacheFile != "" && sizeGB == DefaultVhdxSizeGB {
+		if _, err := os.Stat(cacheFile); err == nil {
+			if err := CopyFile(cacheFile, destFile, false); err != nil {
+				return fmt.Errorf("failed to copy cached file '%s' to '%s': %s", cacheFile, destFile, err)
+			}
+			logrus.Debugf("opengcs: CreateExt4Vhdx: %s fulfilled from cache", destFile)
+			return nil
+		}
+	}
+
+	// Must have a utility VM to operate on
+	if config.Uvm == nil {
+		return fmt.Errorf("no utility VM")
+	}
+
+	// Create the VHDX
+	if err := winio.CreateVhdx(destFile, sizeGB, defaultVhdxBlockSizeMB); err != nil {
+		return fmt.Errorf("failed to create VHDx %s: %s", destFile, err)
+	}
+
+	// Attach it to the utility VM, but don't mount it (as there's no filesystem on it)
+	if err := config.HotAddVhd(destFile, "", false, false); err != nil {
+		return fmt.Errorf("opengcs: CreateExt4Vhdx: failed to hot-add %s to utility VM: %s", cacheFile, err)
+	}
+
+	// Get the list of mapped virtual disks to find the controller and LUN IDs
+	logrus.Debugf("opengcs: CreateExt4Vhdx: %s querying mapped virtual disks", destFile)
+	mvdControllers, err := config.Uvm.MappedVirtualDisks()
+	if err != nil {
+		return fmt.Errorf("failed to get mapped virtual disks: %s", err)
+	}
+
+	// Find our mapped disk from the list of all currently added.
+	controller := -1
+	lun := -1
+	for controllerNumber, controllerElement := range mvdControllers {
+		for diskNumber, diskElement := range controllerElement.MappedVirtualDisks {
+			if diskElement.HostPath == destFile {
+				controller = controllerNumber
+				lun = diskNumber
+				break
+			}
+		}
+	}
+	if controller == -1 || lun == -1 {
+		config.dismount(destFile)
+		return fmt.Errorf("failed to find %s in mapped virtual disks after hot-adding", destFile)
+	}
+	logrus.Debugf("opengcs: CreateExt4Vhdx: %s at C=%d L=%d", destFile, controller, lun)
+
+	// Validate /sys/bus/scsi/devices/C:0:0:L exists as a directory
+	testdCommand := fmt.Sprintf(`test -d /sys/bus/scsi/devices/%d:0:0:%d`, controller, lun)
+	testdProc, err := config.RunProcess(testdCommand, nil, nil, nil)
+	if err != nil {
+		config.dismount(destFile)
+		return fmt.Errorf("failed to `%s` following hot-add %s to utility VM: %s", testdCommand, destFile, err)
+	}
+	defer testdProc.Close()
+	testdProc.WaitTimeout(time.Duration(int(time.Second) * config.UvmTimeoutSeconds))
+	testdExitCode, err := testdProc.ExitCode()
+	if err != nil {
+		config.dismount(destFile)
+		return fmt.Errorf("failed to get exit code from `%s` following hot-add %s to utility VM: %s", testdCommand, destFile, err)
+	}
+	if testdExitCode != 0 {
+		config.dismount(destFile)
+		return fmt.Errorf("`%s` return non-zero exit code (%d) following hot-add %s to utility VM", testdCommand, testdExitCode, destFile)
+	}
+
+	// Get the device from under the block subdirectory by doing a simple ls. This will come back as (eg) `sda`
+	lsCommand := fmt.Sprintf(`ls /sys/bus/scsi/devices/%d:0:0:%d/block`, controller, lun)
+	var lsOutput bytes.Buffer
+	lsProc, err := config.RunProcess(lsCommand, nil, &lsOutput, nil)
+	if err != nil {
+		config.dismount(destFile)
+		return fmt.Errorf("failed to `%s` following hot-add %s to utility VM: %s", lsCommand, destFile, err)
+	}
+	defer lsProc.Close()
+	lsProc.WaitTimeout(time.Duration(int(time.Second) * config.UvmTimeoutSeconds))
+	lsExitCode, err := lsProc.ExitCode()
+	if err != nil {
+		config.dismount(destFile)
+		return fmt.Errorf("failed to get exit code from `%s` following hot-add %s to utility VM: %s", lsCommand, destFile, err)
+	}
+	if lsExitCode != 0 {
+		config.dismount(destFile)
+		return fmt.Errorf("`%s` return non-zero exit code (%d) following hot-add %s to utility VM", lsCommand, lsExitCode, destFile)
+	}
+	device := fmt.Sprintf(`/dev/%s`, strings.TrimSpace(lsOutput.String()))
+	logrus.Debugf("opengcs: CreateExt4Vhdx: %s: device at %s", destFile, device)
+
+	// Format it ext4
+	mkfsCommand := fmt.Sprintf(`mkfs.ext4 -q -E lazy_itable_init=1 -O ^has_journal,sparse_super2,uninit_bg,^resize_inode %s`, device)
+	var mkfsStderr bytes.Buffer
+	mkfsProc, err := config.RunProcess(mkfsCommand, nil, nil, &mkfsStderr)
+	if err != nil {
+		config.dismount(destFile)
+		return fmt.Errorf("failed to RunProcess %q following hot-add %s to utility VM: %s", destFile, mkfsCommand, err)
+	}
+	defer mkfsProc.Close()
+	mkfsProc.WaitTimeout(time.Duration(int(time.Second) * config.UvmTimeoutSeconds))
+	mkfsExitCode, err := mkfsProc.ExitCode()
+	if err != nil {
+		config.dismount(destFile)
+		return fmt.Errorf("failed to get exit code from `%s` following hot-add %s to utility VM: %s", mkfsCommand, destFile, err)
+	}
+	if mkfsExitCode != 0 {
+		config.dismount(destFile)
+		return fmt.Errorf("`%s` return non-zero exit code (%d) following hot-add %s to utility VM: %s", mkfsCommand, mkfsExitCode, destFile, strings.TrimSpace(mkfsStderr.String()))
+	}
+
+	// Dismount before we copy it
+	if err := config.dismount(destFile); err != nil {
+		return fmt.Errorf("failed to hot-remove: %s", err)
+	}
+
+	// Populate the cache.
+	if cacheFile != "" && (sizeGB == DefaultVhdxSizeGB) {
+		if err := CopyFile(destFile, cacheFile, true); err != nil {
+			return fmt.Errorf("failed to seed cache '%s' from '%s': %s", destFile, cacheFile, err)
+		}
+	}
+
+	logrus.Debugf("opengcs: CreateExt4Vhdx: %s created (non-cache)", destFile)
+	return nil
+}

vendor/github.com/Microsoft/opengcs/client/hotaddvhd.go

@@ -0,0 +1,40 @@
+// +build windows
+
+package client
+
+import (
+	"fmt"
+
+	"github.com/Microsoft/hcsshim"
+	"github.com/sirupsen/logrus"
+)
+
+// HotAddVhd hot-adds a VHD to a utility VM. This is used in the global one-utility-VM-
+// service-VM per host scenario. In order to do a graphdriver `Diff`, we hot-add the
+// sandbox to /mnt/<id> so that we can run `exportSandbox` inside the utility VM to
+// get a tar-stream of the sandboxes contents back to the daemon.
+func (config *Config) HotAddVhd(hostPath string, containerPath string, readOnly bool, mount bool) error {
+	logrus.Debugf("opengcs: HotAddVhd: %s: %s", hostPath, containerPath)
+
+	if config.Uvm == nil {
+		return fmt.Errorf("cannot hot-add VHD as no utility VM is in configuration")
+	}
+
+	modification := &hcsshim.ResourceModificationRequestResponse{
+		Resource: "MappedVirtualDisk",
+		Data: hcsshim.MappedVirtualDisk{
+			HostPath:          hostPath,
+			ContainerPath:     containerPath,
+			CreateInUtilityVM: true,
+			ReadOnly:          readOnly,
+			AttachOnly:        !mount,
+		},
+		Request: "Add",
+	}
+
+	if err := config.Uvm.Modify(modification); err != nil {
+		return fmt.Errorf("failed to modify utility VM configuration for hot-add: %s", err)
+	}
+	logrus.Debugf("opengcs: HotAddVhd: %s added successfully", hostPath)
+	return nil
+}

vendor/github.com/Microsoft/opengcs/client/hotremovevhd.go

@@ -0,0 +1,34 @@
+// +build windows
+
+package client
+
+import (
+	"fmt"
+
+	"github.com/Microsoft/hcsshim"
+	"github.com/sirupsen/logrus"
+)
+
+// HotRemoveVhd hot-removes a VHD from a utility VM. This is used in the global one-utility-VM-
+// service-VM per host scenario.
+func (config *Config) HotRemoveVhd(hostPath string) error {
+	logrus.Debugf("opengcs: HotRemoveVhd: %s", hostPath)
+
+	if config.Uvm == nil {
+		return fmt.Errorf("cannot hot-add VHD as no utility VM is in configuration")
+	}
+
+	modification := &hcsshim.ResourceModificationRequestResponse{
+		Resource: "MappedVirtualDisk",
+		Data: hcsshim.MappedVirtualDisk{
+			HostPath:          hostPath,
+			CreateInUtilityVM: true,
+		},
+		Request: "Remove",
+	}
+	if err := config.Uvm.Modify(modification); err != nil {
+		return fmt.Errorf("failed modifying utility VM for hot-remove %s: %s", hostPath, err)
+	}
+	logrus.Debugf("opengcs: HotRemoveVhd: %s removed successfully", hostPath)
+	return nil
+}

vendor/github.com/Microsoft/opengcs/client/layervhddetails.go

@@ -0,0 +1,31 @@
+// +build windows
+
+package client
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// LayerVhdDetails is a utility for getting a file name, size and indication of
+// sandbox for a VHD(x) in a folder. A read-only layer will be layer.vhd. A
+// read-write layer will be sandbox.vhdx.
+func LayerVhdDetails(folder string) (string, int64, bool, error) {
+	var fileInfo os.FileInfo
+	isSandbox := false
+	filename := filepath.Join(folder, "layer.vhd")
+	var err error
+
+	if fileInfo, err = os.Stat(filename); err != nil {
+		filename = filepath.Join(folder, "sandbox.vhdx")
+		if fileInfo, err = os.Stat(filename); err != nil {
+			if os.IsNotExist(err) {
+				return "", 0, isSandbox, fmt.Errorf("could not find layer or sandbox in %s", folder)
+			}
+			return "", 0, isSandbox, fmt.Errorf("error locating layer or sandbox in %s: %s", folder, err)
+		}
+		isSandbox = true
+	}
+	return filename, fileInfo.Size(), isSandbox, nil
+}

vendor/github.com/Microsoft/opengcs/client/process.go

@@ -0,0 +1,112 @@
+// +build windows
+
+package client
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/Microsoft/hcsshim"
+	"github.com/sirupsen/logrus"
+)
+
+// Process is the structure pertaining to a process running in a utility VM.
+type process struct {
+	Process hcsshim.Process
+	Stdin   io.WriteCloser
+	Stdout  io.ReadCloser
+	Stderr  io.ReadCloser
+}
+
+// createUtilsProcess is a convenient wrapper for hcsshim.createUtilsProcess to use when
+// communicating with a utility VM.
+func (config *Config) createUtilsProcess(commandLine string) (process, error) {
+	logrus.Debugf("opengcs: createUtilsProcess")
+
+	if config.Uvm == nil {
+		return process{}, fmt.Errorf("cannot create utils process as no utility VM is in configuration")
+	}
+
+	var (
+		err  error
+		proc process
+	)
+
+	env := make(map[string]string)
+	env["PATH"] = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:"
+	processConfig := &hcsshim.ProcessConfig{
+		EmulateConsole:    false,
+		CreateStdInPipe:   true,
+		CreateStdOutPipe:  true,
+		CreateStdErrPipe:  true,
+		CreateInUtilityVm: true,
+		WorkingDirectory:  "/bin",
+		Environment:       env,
+		CommandLine:       commandLine,
+	}
+	proc.Process, err = config.Uvm.CreateProcess(processConfig)
+	if err != nil {
+		return process{}, fmt.Errorf("failed to create process (%+v) in utility VM: %s", config, err)
+	}
+
+	if proc.Stdin, proc.Stdout, proc.Stderr, err = proc.Process.Stdio(); err != nil {
+		proc.Process.Kill() // Should this have a timeout?
+		proc.Process.Close()
+		return process{}, fmt.Errorf("failed to get stdio pipes for process %+v: %s", config, err)
+	}
+
+	logrus.Debugf("opengcs: createUtilsProcess success: pid %d", proc.Process.Pid())
+	return proc, nil
+}
+
+// RunProcess runs the given command line program in the utilityVM. It takes in
+// an input to the reader to feed into stdin and returns stdout to output.
+// IMPORTANT: It is the responsibility of the caller to call Close() on the returned process.
+func (config *Config) RunProcess(commandLine string, stdin io.Reader, stdout io.Writer, stderr io.Writer) (hcsshim.Process, error) {
+	logrus.Debugf("opengcs: RunProcess: %s", commandLine)
+	process, err := config.createUtilsProcess(commandLine)
+	if err != nil {
+		return nil, err
+	}
+
+	// Send the data into the process's stdin
+	if stdin != nil {
+		if _, err = copyWithTimeout(process.Stdin,
+			stdin,
+			0,
+			config.UvmTimeoutSeconds,
+			fmt.Sprintf("send to stdin of %s", commandLine)); err != nil {
+			return nil, err
+		}
+
+		// Don't need stdin now we've sent everything. This signals GCS that we are finished sending data.
+		if err := process.Process.CloseStdin(); err != nil {
+			return nil, err
+		}
+	}
+
+	if stdout != nil {
+		// Copy the data over to the writer.
+		if _, err := copyWithTimeout(stdout,
+			process.Stdout,
+			0,
+			config.UvmTimeoutSeconds,
+			fmt.Sprintf("RunProcess: copy back from %s", commandLine)); err != nil {
+			return nil, err
+		}
+	}
+
+	if stderr != nil {
+		// Copy the data over to the writer.
+		if _, err := copyWithTimeout(stderr,
+			process.Stderr,
+			0,
+			config.UvmTimeoutSeconds,
+			fmt.Sprintf("RunProcess: copy back from %s", commandLine)); err != nil {
+			return nil, err
+		}
+	}
+
+	logrus.Debugf("opengcs: runProcess success: %s", commandLine)
+	return process.Process, nil
+}

vendor/github.com/Microsoft/opengcs/client/tartovhd.go

@@ -0,0 +1,44 @@
+// +build windows
+
+package client
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/sirupsen/logrus"
+)
+
+// TarToVhd streams a tarstream contained in an io.Reader to a fixed vhd file
+func (config *Config) TarToVhd(targetVHDFile string, reader io.Reader) (int64, error) {
+	logrus.Debugf("opengcs: TarToVhd: %s", targetVHDFile)
+
+	if config.Uvm == nil {
+		return 0, fmt.Errorf("cannot Tar2Vhd as no utility VM is in configuration")
+	}
+
+	process, err := config.createUtilsProcess("tar2vhd")
+	if err != nil {
+		return 0, fmt.Errorf("failed to start tar2vhd for %s: %s", targetVHDFile, err)
+	}
+	defer process.Process.Close()
+
+	// Send the tarstream into the `tar2vhd`s stdin
+	if _, err = copyWithTimeout(process.Stdin, reader, 0, config.UvmTimeoutSeconds, fmt.Sprintf("stdin of tar2vhd for generating %s", targetVHDFile)); err != nil {
+		return 0, fmt.Errorf("failed sending to tar2vhd for %s: %s", targetVHDFile, err)
+	}
+
+	// Don't need stdin now we've sent everything. This signals GCS that we are finished sending data.
+	if err := process.Process.CloseStdin(); err != nil {
+		return 0, fmt.Errorf("failed closing stdin handle for %s: %s", targetVHDFile, err)
+	}
+
+	// Write stdout contents of `tar2vhd` to the VHD file
+	payloadSize, err := writeFileFromReader(targetVHDFile, process.Stdout, config.UvmTimeoutSeconds, fmt.Sprintf("stdout of tar2vhd to %s", targetVHDFile))
+	if err != nil {
+		return 0, fmt.Errorf("failed to write %s during tar2vhd: %s", targetVHDFile, err)
+	}
+
+	logrus.Debugf("opengcs: TarToVhd: %s created, %d bytes", targetVHDFile, payloadSize)
+	return payloadSize, err
+}

vendor/github.com/Microsoft/opengcs/client/unsupported.go

@@ -0,0 +1,3 @@
+// +build !windows
+
+package client

vendor/github.com/Microsoft/opengcs/client/utilities.go

@@ -0,0 +1,99 @@
+// +build windows
+
+package client
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"syscall"
+	"time"
+	"unsafe"
+
+	"github.com/sirupsen/logrus"
+)
+
+var (
+	modkernel32   = syscall.NewLazyDLL("kernel32.dll")
+	procCopyFileW = modkernel32.NewProc("CopyFileW")
+)
+
+// writeFileFromReader writes an output file from an io.Reader
+func writeFileFromReader(path string, reader io.Reader, timeoutSeconds int, context string) (int64, error) {
+	outFile, err := os.Create(path)
+	if err != nil {
+		return 0, fmt.Errorf("opengcs: writeFileFromReader: failed to create %s: %s", path, err)
+	}
+	defer outFile.Close()
+	return copyWithTimeout(outFile, reader, 0, timeoutSeconds, context)
+}
+
+// copyWithTimeout is a wrapper for io.Copy using a timeout duration
+func copyWithTimeout(dst io.Writer, src io.Reader, size int64, timeoutSeconds int, context string) (int64, error) {
+	logrus.Debugf("opengcs: copywithtimeout: size %d: timeout %d: (%s)", size, timeoutSeconds, context)
+
+	type resultType struct {
+		err   error
+		bytes int64
+	}
+
+	done := make(chan resultType, 1)
+	go func() {
+		result := resultType{}
+		result.bytes, result.err = io.Copy(dst, src)
+		done <- result
+	}()
+
+	var result resultType
+	timedout := time.After(time.Duration(timeoutSeconds) * time.Second)
+
+	select {
+	case <-timedout:
+		return 0, fmt.Errorf("opengcs: copyWithTimeout: timed out (%s)", context)
+	case result = <-done:
+		if result.err != nil && result.err != io.EOF {
+			// See https://github.com/golang/go/blob/f3f29d1dea525f48995c1693c609f5e67c046893/src/os/exec/exec_windows.go for a clue as to why we are doing this :)
+			if se, ok := result.err.(syscall.Errno); ok {
+				const (
+					errNoData     = syscall.Errno(232)
+					errBrokenPipe = syscall.Errno(109)
+				)
+				if se == errNoData || se == errBrokenPipe {
+					logrus.Debugf("opengcs: copyWithTimeout: hit NoData or BrokenPipe: %d: %s", se, context)
+					return result.bytes, nil
+				}
+			}
+			return 0, fmt.Errorf("opengcs: copyWithTimeout: error reading: '%s' after %d bytes (%s)", result.err, result.bytes, context)
+		}
+	}
+	logrus.Debugf("opengcs: copyWithTimeout: success - copied %d bytes (%s)", result.bytes, context)
+	return result.bytes, nil
+}
+
+// CopyFile is a utility for copying a file - used for the sandbox cache.
+// Uses CopyFileW win32 API for performance
+func CopyFile(srcFile, destFile string, overwrite bool) error {
+	var bFailIfExists uint32 = 1
+	if overwrite {
+		bFailIfExists = 0
+	}
+
+	lpExistingFileName, err := syscall.UTF16PtrFromString(srcFile)
+	if err != nil {
+		return err
+	}
+	lpNewFileName, err := syscall.UTF16PtrFromString(destFile)
+	if err != nil {
+		return err
+	}
+	r1, _, err := syscall.Syscall(
+		procCopyFileW.Addr(),
+		3,
+		uintptr(unsafe.Pointer(lpExistingFileName)),
+		uintptr(unsafe.Pointer(lpNewFileName)),
+		uintptr(bFailIfExists))
+	if r1 == 0 {
+		return fmt.Errorf("failed CopyFileW Win32 call from '%s' to '%s': %s", srcFile, destFile, err)
+	}
+	return nil
+}

vendor/github.com/Microsoft/opengcs/client/vhdtotar.go

@@ -0,0 +1,67 @@
+// +build windows
+
+package client
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/sirupsen/logrus"
+)
+
+// VhdToTar does what is says - it exports a VHD in a specified
+// folder (either a read-only layer.vhd, or a read-write sandbox.vhd) to a
+// ReadCloser containing a tar-stream of the layers contents.
+func (config *Config) VhdToTar(vhdFile string, uvmMountPath string, isSandbox bool, vhdSize int64) (io.ReadCloser, error) {
+	logrus.Debugf("opengcs: VhdToTar: %s isSandbox: %t", vhdFile, isSandbox)
+
+	if config.Uvm == nil {
+		return nil, fmt.Errorf("cannot VhdToTar as no utility VM is in configuration")
+	}
+
+	vhdHandle, err := os.Open(vhdFile)
+	if err != nil {
+		return nil, fmt.Errorf("opengcs: VhdToTar: failed to open %s: %s", vhdFile, err)
+	}
+	defer vhdHandle.Close()
+	logrus.Debugf("opengcs: VhdToTar: exporting %s, size %d, isSandbox %t", vhdHandle.Name(), vhdSize, isSandbox)
+
+	// Different binary depending on whether a RO layer or a RW sandbox
+	command := "vhd2tar"
+	if isSandbox {
+		command = fmt.Sprintf("exportSandbox -path %s", uvmMountPath)
+	}
+
+	// Start the binary in the utility VM
+	process, err := config.createUtilsProcess(command)
+	if err != nil {
+		return nil, fmt.Errorf("opengcs: VhdToTar: %s: failed to create utils process %s: %s", vhdHandle.Name(), command, err)
+	}
+
+	if !isSandbox {
+		// Send the VHD contents to the utility VM processes stdin handle if not a sandbox
+		logrus.Debugf("opengcs: VhdToTar: copying the layer VHD into the utility VM")
+		if _, err = copyWithTimeout(process.Stdin, vhdHandle, vhdSize, config.UvmTimeoutSeconds, fmt.Sprintf("vhdtotarstream: sending %s to %s", vhdHandle.Name(), command)); err != nil {
+			process.Process.Close()
+			return nil, fmt.Errorf("opengcs: VhdToTar: %s: failed to copyWithTimeout on the stdin pipe (to utility VM): %s", vhdHandle.Name(), err)
+		}
+	}
+
+	// Start a goroutine which copies the stdout (ie the tar stream)
+	reader, writer := io.Pipe()
+	go func() {
+		defer writer.Close()
+		defer process.Process.Close()
+		logrus.Debugf("opengcs: VhdToTar: copying tar stream back from the utility VM")
+		bytes, err := copyWithTimeout(writer, process.Stdout, vhdSize, config.UvmTimeoutSeconds, fmt.Sprintf("vhdtotarstream: copy tarstream from %s", command))
+		if err != nil {
+			logrus.Errorf("opengcs: VhdToTar: %s:  copyWithTimeout on the stdout pipe (from utility VM) failed: %s", vhdHandle.Name(), err)
+		}
+		logrus.Debugf("opengcs: VhdToTar: copied %d bytes of the tarstream of %s from the utility VM", bytes, vhdHandle.Name())
+	}()
+
+	// Return the read-side of the pipe connected to the goroutine which is reading from the stdout of the process in the utility VM
+	return reader, nil
+
+}