Initial

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

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

@@ -0,0 +1,56 @@
+package wclayer
+
+import (
+	"syscall"
+
+	"github.com/Microsoft/hcsshim/internal/hcserror"
+	"github.com/sirupsen/logrus"
+)
+
+// GetLayerMountPath will look for a mounted layer with the given path and return
+// the path at which that layer can be accessed.  This path may be a volume path
+// if the layer is a mounted read-write layer, otherwise it is expected to be the
+// folder path at which the layer is stored.
+func GetLayerMountPath(path string) (_ string, err error) {
+	title := "hcsshim::GetLayerMountPath"
+	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")
+		}
+	}()
+
+	var mountPathLength uintptr
+	mountPathLength = 0
+
+	// Call the procedure itself.
+	logrus.WithFields(fields).Debug("Calling proc (1)")
+	err = getLayerMountPath(&stdDriverInfo, path, &mountPathLength, nil)
+	if err != nil {
+		return "", hcserror.New(err, title+" - failed", "(first call)")
+	}
+
+	// Allocate a mount path of the returned length.
+	if mountPathLength == 0 {
+		return "", nil
+	}
+	mountPathp := make([]uint16, mountPathLength)
+	mountPathp[0] = 0
+
+	// Call the procedure again
+	logrus.WithFields(fields).Debug("Calling proc (2)")
+	err = getLayerMountPath(&stdDriverInfo, path, &mountPathLength, &mountPathp[0])
+	if err != nil {
+		return "", hcserror.New(err, title+" - failed", "(second call)")
+	}
+
+	mountPath := syscall.UTF16ToString(mountPathp[0:])
+	fields["mountPath"] = mountPath
+	return mountPath, nil
+}