oci: join crio-conmon for cgroupfs

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

vendor/github.com/containerd/cgroups/pids.go

@@ -0,0 +1,69 @@
+package cgroups
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+func NewPids(root string) *pidsController {
+	return &pidsController{
+		root: filepath.Join(root, string(Pids)),
+	}
+}
+
+type pidsController struct {
+	root string
+}
+
+func (p *pidsController) Name() Name {
+	return Pids
+}
+
+func (p *pidsController) Path(path string) string {
+	return filepath.Join(p.root, path)
+}
+
+func (p *pidsController) Create(path string, resources *specs.LinuxResources) error {
+	if err := os.MkdirAll(p.Path(path), defaultDirPerm); err != nil {
+		return err
+	}
+	if resources.Pids != nil && resources.Pids.Limit > 0 {
+		return ioutil.WriteFile(
+			filepath.Join(p.Path(path), "pids.max"),
+			[]byte(strconv.FormatInt(resources.Pids.Limit, 10)),
+			defaultFilePerm,
+		)
+	}
+	return nil
+}
+
+func (p *pidsController) Update(path string, resources *specs.LinuxResources) error {
+	return p.Create(path, resources)
+}
+
+func (p *pidsController) Stat(path string, stats *Stats) error {
+	current, err := readUint(filepath.Join(p.Path(path), "pids.current"))
+	if err != nil {
+		return err
+	}
+	var max uint64
+	maxData, err := ioutil.ReadFile(filepath.Join(p.Path(path), "pids.max"))
+	if err != nil {
+		return err
+	}
+	if maxS := strings.TrimSpace(string(maxData)); maxS != "max" {
+		if max, err = parseUint(maxS, 10, 64); err != nil {
+			return err
+		}
+	}
+	stats.Pids = &PidsStat{
+		Current: current,
+		Limit:   max,
+	}
+	return nil
+}