v1.go (1849B)
1 /* 2 Copyright The containerd Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package cgroup1 18 19 import ( 20 "bufio" 21 "fmt" 22 "os" 23 "path/filepath" 24 "strings" 25 ) 26 27 // Default returns all the groups in the default cgroups mountpoint in a single hierarchy 28 func Default() ([]Subsystem, error) { 29 root, err := v1MountPoint() 30 if err != nil { 31 return nil, err 32 } 33 subsystems, err := defaults(root) 34 if err != nil { 35 return nil, err 36 } 37 var enabled []Subsystem 38 for _, s := range pathers(subsystems) { 39 // check and remove the default groups that do not exist 40 if _, err := os.Lstat(s.Path("/")); err == nil { 41 enabled = append(enabled, s) 42 } 43 } 44 return enabled, nil 45 } 46 47 // v1MountPoint returns the mount point where the cgroup 48 // mountpoints are mounted in a single hiearchy 49 func v1MountPoint() (string, error) { 50 f, err := os.Open("/proc/self/mountinfo") 51 if err != nil { 52 return "", err 53 } 54 defer f.Close() 55 scanner := bufio.NewScanner(f) 56 for scanner.Scan() { 57 var ( 58 text = scanner.Text() 59 fields = strings.Split(text, " ") 60 numFields = len(fields) 61 ) 62 if numFields < 10 { 63 return "", fmt.Errorf("mountinfo: bad entry %q", text) 64 } 65 if fields[numFields-3] == "cgroup" { 66 return filepath.Dir(fields[4]), nil 67 } 68 } 69 if err := scanner.Err(); err != nil { 70 return "", err 71 } 72 return "", ErrMountPointNotExist 73 }