Fix build on non-Linux OSes

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #1266
Approved by: baude

libpod/util_linux.go

@@ -0,0 +1,69 @@
+// +build linux
+
+package libpod
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/containerd/cgroups"
+	spec "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// systemdSliceFromPath makes a new systemd slice under the given parent with
+// the given name.
+// The parent must be a slice. The name must NOT include ".slice"
+func systemdSliceFromPath(parent, name string) (string, error) {
+	cgroupPath, err := assembleSystemdCgroupName(parent, name)
+	if err != nil {
+		return "", err
+	}
+
+	logrus.Debugf("Created cgroup path %s for parent %s and name %s", cgroupPath, parent, name)
+
+	if err := makeSystemdCgroup(cgroupPath); err != nil {
+		return "", errors.Wrapf(err, "error creating cgroup %s", cgroupPath)
+	}
+
+	logrus.Debugf("Created cgroup %s", cgroupPath)
+
+	return cgroupPath, nil
+}
+
+// makeSystemdCgroup creates a systemd CGroup at the given location.
+func makeSystemdCgroup(path string) error {
+	controller, err := cgroups.NewSystemd(SystemdDefaultCgroupParent)
+	if err != nil {
+		return err
+	}
+
+	return controller.Create(path, &spec.LinuxResources{})
+}
+
+// deleteSystemdCgroup deletes the systemd cgroup at the given location
+func deleteSystemdCgroup(path string) error {
+	controller, err := cgroups.NewSystemd(SystemdDefaultCgroupParent)
+	if err != nil {
+		return err
+	}
+
+	return controller.Delete(path)
+}
+
+// assembleSystemdCgroupName creates a systemd cgroup path given a base and
+// a new component to add.
+// The base MUST be systemd slice (end in .slice)
+func assembleSystemdCgroupName(baseSlice, newSlice string) (string, error) {
+	const sliceSuffix = ".slice"
+
+	if !strings.HasSuffix(baseSlice, sliceSuffix) {
+		return "", errors.Wrapf(ErrInvalidArg, "cannot assemble cgroup path with base %q - must end in .slice", baseSlice)
+	}
+
+	noSlice := strings.TrimSuffix(baseSlice, sliceSuffix)
+	final := fmt.Sprintf("%s/%s-%s%s", baseSlice, noSlice, newSlice, sliceSuffix)
+
+	return final, nil
+}