| package cgroups |
| |
| import ( |
| "bufio" |
| "fmt" |
| "os" |
| "path/filepath" |
| "strings" |
| ) |
| |
| // V1 returns all the groups in the default cgroups mountpoint in a single hierarchy |
| func V1() ([]Subsystem, error) { |
| root, err := v1MountPoint() |
| if err != nil { |
| return nil, err |
| } |
| subsystems, err := defaults(root) |
| if err != nil { |
| return nil, err |
| } |
| var enabled []Subsystem |
| for _, s := range pathers(subsystems) { |
| // check and remove the default groups that do not exist |
| if _, err := os.Lstat(s.Path("/")); err == nil { |
| enabled = append(enabled, s) |
| } |
| } |
| return enabled, nil |
| } |
| |
| // v1MountPoint returns the mount point where the cgroup |
| // mountpoints are mounted in a single hiearchy |
| func v1MountPoint() (string, error) { |
| f, err := os.Open("/proc/self/mountinfo") |
| if err != nil { |
| return "", err |
| } |
| defer f.Close() |
| scanner := bufio.NewScanner(f) |
| for scanner.Scan() { |
| if err := scanner.Err(); err != nil { |
| return "", err |
| } |
| var ( |
| text = scanner.Text() |
| fields = strings.Split(text, " ") |
| // safe as mountinfo encodes mountpoints with spaces as \040. |
| index = strings.Index(text, " - ") |
| postSeparatorFields = strings.Fields(text[index+3:]) |
| numPostFields = len(postSeparatorFields) |
| ) |
| // this is an error as we can't detect if the mount is for "cgroup" |
| if numPostFields == 0 { |
| return "", fmt.Errorf("Found no fields post '-' in %q", text) |
| } |
| if postSeparatorFields[0] == "cgroup" { |
| // check that the mount is properly formated. |
| if numPostFields < 3 { |
| return "", fmt.Errorf("Error found less than 3 fields post '-' in %q", text) |
| } |
| return filepath.Dir(fields[4]), nil |
| } |
| } |
| return "", ErrMountPointNotExist |
| } |