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