vendor: initial vendor

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/Microsoft/hcsshim/internal/wclayer/layerexists.go

@@ -0,0 +1,33 @@
+package wclayer
+
+import (
+	"github.com/Microsoft/hcsshim/internal/hcserror"
+	"github.com/sirupsen/logrus"
+)
+
+// LayerExists will return true if a layer with the given id exists and is known
+// to the system.
+func LayerExists(path string) (_ bool, err error) {
+	title := "hcsshim::LayerExists"
+	fields := logrus.Fields{
+		"path": path,
+	}
+	logrus.WithFields(fields).Debug(title)
+	defer func() {
+		if err != nil {
+			fields[logrus.ErrorKey] = err
+			logrus.WithFields(fields).Error(err)
+		} else {
+			logrus.WithFields(fields).Debug(title + " - succeeded")
+		}
+	}()
+
+	// Call the procedure itself.
+	var exists uint32
+	err = layerExists(&stdDriverInfo, path, &exists)
+	if err != nil {
+		return false, hcserror.New(err, title+" - failed", "")
+	}
+	fields["layer-exists"] = exists != 0
+	return exists != 0, nil
+}