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cgroup.go
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cgroup.go
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// Copyright 2015 The rkt Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//+build linux
package cgroup
import (
"errors"
"path/filepath"
"syscall"
"github.com/hashicorp/errwrap"
"github.com/rkt/rkt/common/cgroup/v1"
"github.com/rkt/rkt/common/cgroup/v2"
)
const (
// The following const comes from
// #define CGROUP2_SUPER_MAGIC 0x63677270
// https://github.com/torvalds/linux/blob/v4.6/include/uapi/linux/magic.h#L58
Cgroup2fsMagicNumber = 0x63677270
)
// IsIsolatorSupported returns whether an isolator is supported in the kernel
func IsIsolatorSupported(isolator string) (bool, error) {
isUnified, err := IsCgroupUnified("/")
if err != nil {
return false, errwrap.Wrap(errors.New("error determining cgroup version"), err)
}
if isUnified {
controllers, err := v2.GetEnabledControllers()
if err != nil {
return false, errwrap.Wrap(errors.New("error determining enabled controllers"), err)
}
for _, c := range controllers {
if c == isolator {
return true, nil
}
}
return false, nil
}
return v1.IsControllerMounted(isolator)
}
// IsCgroupUnified checks if cgroup mounted at /sys/fs/cgroup is
// the new unified version (cgroup v2)
func IsCgroupUnified(root string) (bool, error) {
cgroupFsPath := filepath.Join(root, "/sys/fs/cgroup")
var statfs syscall.Statfs_t
if err := syscall.Statfs(cgroupFsPath, &statfs); err != nil {
return false, err
}
return statfs.Type == Cgroup2fsMagicNumber, nil
}