Move cgroups package into libcontainer

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

libcontainer/cgroups/fs/freezer.go

@@ -0,0 +1,72 @@
+package fs
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/dotcloud/docker/pkg/libcontainer/cgroups"
+)
+
+type freezerGroup struct {
+}
+
+func (s *freezerGroup) Set(d *data) error {
+	dir, err := d.join("freezer")
+	if err != nil {
+		if err != cgroups.ErrNotFound {
+			return err
+		}
+		return nil
+	}
+
+	if d.c.Freezer != "" {
+		if err := writeFile(dir, "freezer.state", d.c.Freezer); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (s *freezerGroup) Remove(d *data) error {
+	return removePath(d.path("freezer"))
+}
+
+func (s *freezerGroup) Stats(d *data) (map[string]float64, error) {
+	var (
+		paramData = make(map[string]float64)
+		params    = []string{
+			"parent_freezing",
+			"self_freezing",
+			// comment out right now because this is string "state",
+		}
+	)
+
+	path, err := d.path("freezer")
+	if err != nil {
+		return nil, err
+	}
+
+	for _, param := range params {
+		f, err := os.Open(filepath.Join(path, fmt.Sprintf("freezer.%s", param)))
+		if err != nil {
+			return nil, err
+		}
+		defer f.Close()
+
+		data, err := ioutil.ReadAll(f)
+		if err != nil {
+			return nil, err
+		}
+
+		v, err := strconv.ParseFloat(strings.TrimSuffix(string(data), "\n"), 64)
+		if err != nil {
+			return nil, err
+		}
+		paramData[param] = v
+	}
+	return paramData, nil
+}