Vendor in files for runc/libcontainer

vndr was previously removing .go files in runc/libcontainer since they weren't used anywhere
in cri-o, but kpod stats will use them

Signed-off-by: Ryan Cole <rcyoalne@gmail.com>

vendor/github.com/opencontainers/runc/libcontainer/notify_linux.go

@@ -0,0 +1,90 @@
+// +build linux
+
+package libcontainer
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"golang.org/x/sys/unix"
+)
+
+const oomCgroupName = "memory"
+
+type PressureLevel uint
+
+const (
+	LowPressure PressureLevel = iota
+	MediumPressure
+	CriticalPressure
+)
+
+func registerMemoryEvent(cgDir string, evName string, arg string) (<-chan struct{}, error) {
+	evFile, err := os.Open(filepath.Join(cgDir, evName))
+	if err != nil {
+		return nil, err
+	}
+	fd, err := unix.Eventfd(0, unix.EFD_CLOEXEC)
+	if err != nil {
+		evFile.Close()
+		return nil, err
+	}
+
+	eventfd := os.NewFile(uintptr(fd), "eventfd")
+
+	eventControlPath := filepath.Join(cgDir, "cgroup.event_control")
+	data := fmt.Sprintf("%d %d %s", eventfd.Fd(), evFile.Fd(), arg)
+	if err := ioutil.WriteFile(eventControlPath, []byte(data), 0700); err != nil {
+		eventfd.Close()
+		evFile.Close()
+		return nil, err
+	}
+	ch := make(chan struct{})
+	go func() {
+		defer func() {
+			close(ch)
+			eventfd.Close()
+			evFile.Close()
+		}()
+		buf := make([]byte, 8)
+		for {
+			if _, err := eventfd.Read(buf); err != nil {
+				return
+			}
+			// When a cgroup is destroyed, an event is sent to eventfd.
+			// So if the control path is gone, return instead of notifying.
+			if _, err := os.Lstat(eventControlPath); os.IsNotExist(err) {
+				return
+			}
+			ch <- struct{}{}
+		}
+	}()
+	return ch, nil
+}
+
+// notifyOnOOM returns channel on which you can expect event about OOM,
+// if process died without OOM this channel will be closed.
+func notifyOnOOM(paths map[string]string) (<-chan struct{}, error) {
+	dir := paths[oomCgroupName]
+	if dir == "" {
+		return nil, fmt.Errorf("path %q missing", oomCgroupName)
+	}
+
+	return registerMemoryEvent(dir, "memory.oom_control", "")
+}
+
+func notifyMemoryPressure(paths map[string]string, level PressureLevel) (<-chan struct{}, error) {
+	dir := paths[oomCgroupName]
+	if dir == "" {
+		return nil, fmt.Errorf("path %q missing", oomCgroupName)
+	}
+
+	if level > CriticalPressure {
+		return nil, fmt.Errorf("invalid pressure level %d", level)
+	}
+
+	levelStr := []string{"low", "medium", "critical"}[level]
+	return registerMemoryEvent(dir, "memory.pressure_level", levelStr)
+}