package cgroups import ( "bytes" "fmt" "io/ioutil" "os" "path/filepath" specs "github.com/opencontainers/runtime-spec/specs-go" ) func NewCputset(root string) *cpusetController { return &cpusetController{ root: filepath.Join(root, string(Cpuset)), } } type cpusetController struct { root string } func (c *cpusetController) Name() Name { return Cpuset } func (c *cpusetController) Path(path string) string { return filepath.Join(c.root, path) } func (c *cpusetController) Create(path string, resources *specs.LinuxResources) error { if err := c.ensureParent(c.Path(path), c.root); err != nil { return err } if err := os.MkdirAll(c.Path(path), defaultDirPerm); err != nil { return err } if err := c.copyIfNeeded(c.Path(path), filepath.Dir(c.Path(path))); err != nil { return err } if resources.CPU != nil { for _, t := range []struct { name string value *string }{ { name: "cpus", value: &resources.CPU.Cpus, }, { name: "mems", value: &resources.CPU.Mems, }, } { if t.value != nil { if err := ioutil.WriteFile( filepath.Join(c.Path(path), fmt.Sprintf("cpuset.%s", t.name)), []byte(*t.value), defaultFilePerm, ); err != nil { return err } } } } return nil } func (c *cpusetController) getValues(path string) (cpus []byte, mems []byte, err error) { if cpus, err = ioutil.ReadFile(filepath.Join(path, "cpuset.cpus")); err != nil && !os.IsNotExist(err) { return } if mems, err = ioutil.ReadFile(filepath.Join(path, "cpuset.mems")); err != nil && !os.IsNotExist(err) { return } return cpus, mems, nil } // ensureParent makes sure that the parent directory of current is created // and populated with the proper cpus and mems files copied from // it's parent. func (c *cpusetController) ensureParent(current, root string) error { parent := filepath.Dir(current) if _, err := filepath.Rel(root, parent); err != nil { return nil } // Avoid infinite recursion. if parent == current { return fmt.Errorf("cpuset: cgroup parent path outside cgroup root") } if cleanPath(parent) != root { if err := c.ensureParent(parent, root); err != nil { return err } } if err := os.MkdirAll(current, defaultDirPerm); err != nil { return err } return c.copyIfNeeded(current, parent) } // copyIfNeeded copies the cpuset.cpus and cpuset.mems from the parent // directory to the current directory if the file's contents are 0 func (c *cpusetController) copyIfNeeded(current, parent string) error { var ( err error currentCpus, currentMems []byte parentCpus, parentMems []byte ) if currentCpus, currentMems, err = c.getValues(current); err != nil { return err } if parentCpus, parentMems, err = c.getValues(parent); err != nil { return err } if isEmpty(currentCpus) { if err := ioutil.WriteFile( filepath.Join(current, "cpuset.cpus"), parentCpus, defaultFilePerm, ); err != nil { return err } } if isEmpty(currentMems) { if err := ioutil.WriteFile( filepath.Join(current, "cpuset.mems"), parentMems, defaultFilePerm, ); err != nil { return err } } return nil } func isEmpty(b []byte) bool { return len(bytes.Trim(b, "\n")) == 0 }