Revendor github.com/Microsoft/hcsshim

1. Revendors github.com/Microsoft/hcsshim to the latest known good commit.
This includes numerous bug fixes and improvements.

2. Vendors indirect dependency on go.opencensus.io since hcsshim now uses trace
correlation.

Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>

vendor/github.com/Microsoft/hcsshim/pkg/go-runhcs/runhcs_create-scratch.go

@@ -2,9 +2,53 @@ package runhcs
 
 import (
 	"context"
+	"errors"
+	"path/filepath"
+	"strconv"
 )
 
 // CreateScratch creates a scratch vhdx at 'destpath' that is ext4 formatted.
 func (r *Runhcs) CreateScratch(context context.Context, destpath string) error {
-	return r.runOrError(r.command(context, "create-scratch", "--destpath", destpath))
+	return r.CreateScratchWithOpts(context, destpath, nil)
+}
+
+// CreateScratchOpts is the set of options that can be used with the
+// `CreateScratchWithOpts` command.
+type CreateScratchOpts struct {
+	// SizeGB is the size in GB of the scratch file to create.
+	SizeGB int
+	// CacheFile is the path to an existing `scratch.vhx` to copy. If
+	// `CacheFile` does not exit the scratch will be created.
+	CacheFile string
+}
+
+func (opt *CreateScratchOpts) args() ([]string, error) {
+	var out []string
+	if opt.SizeGB < 0 {
+		return nil, errors.New("sizeGB must be >= 0")
+	} else if opt.SizeGB > 0 {
+		out = append(out, "--sizeGB", strconv.Itoa(opt.SizeGB))
+	}
+	if opt.CacheFile != "" {
+		abs, err := filepath.Abs(opt.CacheFile)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, "--cache-path", abs)
+	}
+	return out, nil
+}
+
+// CreateScratchWithOpts creates a scratch vhdx at 'destpath' that is ext4
+// formatted based on `opts`.
+func (r *Runhcs) CreateScratchWithOpts(context context.Context, destpath string, opts *CreateScratchOpts) error {
+	args := []string{"create-scratch", "--destpath", destpath}
+	if opts != nil {
+		oargs, err := opts.args()
+		if err != nil {
+			return err
+		}
+		args = append(args, oargs...)
+	}
+	return r.runOrError(r.command(context, args...))
 }