go-sandbox/pkg/cgroup/subcgroup.go

72 lines
1.6 KiB
Go

package cgroup
import (
"errors"
"io/ioutil"
"path"
"strconv"
"strings"
"syscall"
)
// SubCGroup is the sub-cgroup
type SubCGroup struct {
path string
}
// ErrNotInitialized returned when trying to read from not initialized cgroup
var ErrNotInitialized = errors.New("cgroup was not initialized")
// NewSubCGroup creates a sug CGroup
func NewSubCGroup(p string) *SubCGroup {
return &SubCGroup{
path: p,
}
}
// WriteUint writes uint64 into given file
func (c *SubCGroup) WriteUint(filename string, i uint64) error {
if c.path == "" {
return nil
}
return c.WriteFile(filename, []byte(strconv.FormatUint(i, 10)))
}
// ReadUint read uint64 into given file
func (c *SubCGroup) ReadUint(filename string) (uint64, error) {
if c.path == "" {
return 0, ErrNotInitialized
}
b, err := c.ReadFile(filename)
if err != nil {
return 0, err
}
s, err := strconv.ParseUint(strings.TrimSpace(string(b)), 10, 64)
if err != nil {
return 0, err
}
return s, nil
}
// WriteFile writes cgroup file and handles potential EINTR error while writes to
// the slow device (cgroup)
func (c *SubCGroup) WriteFile(name string, content []byte) error {
p := path.Join(c.path, name)
err := ioutil.WriteFile(p, content, 0664)
for err != nil && errors.Is(err, syscall.EINTR) {
err = ioutil.WriteFile(p, content, 0664)
}
return err
}
// ReadFile reads cgroup file and handles potential EINTR error while read to
// the slow device (cgroup)
func (c *SubCGroup) ReadFile(name string) ([]byte, error) {
p := path.Join(c.path, name)
data, err := ioutil.ReadFile(p)
for err != nil && errors.Is(err, syscall.EINTR) {
data, err = ioutil.ReadFile(p)
}
return data, err
}