add cgroup pids test for runtime

Signed-off-by: Ma Shimiao <mashimiao.fnst@cn.fujitsu.com>

Author: Ma Shimiao

validation/linux_cgroups_pids.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/opencontainers/runtime-tools/cgroups"
+	"github.com/opencontainers/runtime-tools/validation/util"
+)
+
+func main() {
+	var limit int64 = 1000
+	g := util.GetDefaultGenerator()
+	g.SetLinuxCgroupsPath("/test")
+	g.SetLinuxResourcesPidsLimit(limit)
+	err := util.RuntimeOutsideValidate(g, func(path string) error {
+		cg, err := cgroups.FindCgroup()
+		if err != nil {
+			return err
+		}
+		lpd, err := cg.GetPidsData(path)
+		if err != nil {
+			return err
+		}
+		if lpd.Limit != limit {
+			return fmt.Errorf("pids limit is not set correctly, expect: %d, actual: %d", limit, lpd.Limit)
+		}
+		return nil
+	})
+
+	if err != nil {
+		util.Fatal(err)
+	}
+}