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|
//go:build linux || darwin
// +build linux darwin
package utils
import (
"bufio"
"bytes"
"context"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"strings"
"github.com/containers/common/pkg/cgroups"
"github.com/containers/podman/v4/pkg/rootless"
systemdDbus "github.com/coreos/go-systemd/v22/dbus"
"github.com/godbus/dbus/v5"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
// RunUnderSystemdScope adds the specified pid to a systemd scope
func RunUnderSystemdScope(pid int, slice string, unitName string) error {
var properties []systemdDbus.Property
var conn *systemdDbus.Conn
var err error
if rootless.IsRootless() {
conn, err = cgroups.GetUserConnection(rootless.GetRootlessUID())
if err != nil {
return err
}
} else {
conn, err = systemdDbus.NewWithContext(context.Background())
if err != nil {
return err
}
}
defer conn.Close()
properties = append(properties, systemdDbus.PropSlice(slice))
properties = append(properties, newProp("PIDs", []uint32{uint32(pid)}))
properties = append(properties, newProp("Delegate", true))
properties = append(properties, newProp("DefaultDependencies", false))
ch := make(chan string)
_, err = conn.StartTransientUnitContext(context.Background(), unitName, "replace", properties, ch)
if err != nil {
// On errors check if the cgroup already exists, if it does move the process there
if props, err := conn.GetUnitTypePropertiesContext(context.Background(), unitName, "Scope"); err == nil {
if cgroup, ok := props["ControlGroup"].(string); ok && cgroup != "" {
if err := moveUnderCgroup(cgroup, "", []uint32{uint32(pid)}); err == nil {
return nil
}
// On errors return the original error message we got from StartTransientUnit.
}
}
return err
}
// Block until job is started
<-ch
return nil
}
func getCgroupProcess(procFile string) (string, error) {
f, err := os.Open(procFile)
if err != nil {
return "", err
}
defer f.Close()
scanner := bufio.NewScanner(f)
cgroup := "/"
for scanner.Scan() {
line := scanner.Text()
parts := strings.SplitN(line, ":", 3)
if len(parts) != 3 {
return "", errors.Errorf("cannot parse cgroup line %q", line)
}
if strings.HasPrefix(line, "0::") {
cgroup = line[3:]
break
}
if len(parts[2]) > len(cgroup) {
cgroup = parts[2]
}
}
if cgroup == "/" {
return "", errors.Errorf("could not find cgroup mount in %q", procFile)
}
return cgroup, nil
}
// GetOwnCgroup returns the cgroup for the current process.
func GetOwnCgroup() (string, error) {
return getCgroupProcess("/proc/self/cgroup")
}
// GetCgroupProcess returns the cgroup for the specified process process.
func GetCgroupProcess(pid int) (string, error) {
return getCgroupProcess(fmt.Sprintf("/proc/%d/cgroup", pid))
}
// MoveUnderCgroupSubtree moves the PID under a cgroup subtree.
func MoveUnderCgroupSubtree(subtree string) error {
return moveUnderCgroup("", subtree, nil)
}
// moveUnderCgroup moves a group of processes to a new cgroup.
// If cgroup is the empty string, then the current calling process cgroup is used.
// If processes is empty, then the processes from the current cgroup are moved.
func moveUnderCgroup(cgroup, subtree string, processes []uint32) error {
procFile := "/proc/self/cgroup"
f, err := os.Open(procFile)
if err != nil {
return err
}
defer f.Close()
unifiedMode, err := cgroups.IsCgroup2UnifiedMode()
if err != nil {
return err
}
scanner := bufio.NewScanner(f)
for scanner.Scan() {
line := scanner.Text()
parts := strings.SplitN(line, ":", 3)
if len(parts) != 3 {
return errors.Errorf("cannot parse cgroup line %q", line)
}
// root cgroup, skip it
if parts[2] == "/" {
continue
}
cgroupRoot := "/sys/fs/cgroup"
// Special case the unified mount on hybrid cgroup and named hierarchies.
// This works on Fedora 31, but we should really parse the mounts to see
// where the cgroup hierarchy is mounted.
if parts[1] == "" && !unifiedMode {
// If it is not using unified mode, the cgroup v2 hierarchy is
// usually mounted under /sys/fs/cgroup/unified
cgroupRoot = filepath.Join(cgroupRoot, "unified")
// Ignore the unified mount if it doesn't exist
if _, err := os.Stat(cgroupRoot); err != nil && os.IsNotExist(err) {
continue
}
} else if parts[1] != "" {
// Assume the controller is mounted at /sys/fs/cgroup/$CONTROLLER.
controller := strings.TrimPrefix(parts[1], "name=")
cgroupRoot = filepath.Join(cgroupRoot, controller)
}
parentCgroup := cgroup
if parentCgroup == "" {
parentCgroup = parts[2]
}
newCgroup := filepath.Join(cgroupRoot, parentCgroup, subtree)
if err := os.MkdirAll(newCgroup, 0755); err != nil && !os.IsExist(err) {
return err
}
f, err := os.OpenFile(filepath.Join(newCgroup, "cgroup.procs"), os.O_RDWR, 0755)
if err != nil {
return err
}
defer f.Close()
if len(processes) > 0 {
for _, pid := range processes {
if _, err := f.Write([]byte(fmt.Sprintf("%d\n", pid))); err != nil {
logrus.Debugf("Cannot move process %d to cgroup %q: %v", pid, newCgroup, err)
}
}
} else {
processesData, err := ioutil.ReadFile(filepath.Join(cgroupRoot, parts[2], "cgroup.procs"))
if err != nil {
return err
}
for _, pid := range bytes.Split(processesData, []byte("\n")) {
if len(pid) == 0 {
continue
}
if _, err := f.Write(pid); err != nil {
logrus.Debugf("Cannot move process %s to cgroup %q: %v", string(pid), newCgroup, err)
}
}
}
}
return nil
}
func newProp(name string, units interface{}) systemdDbus.Property {
return systemdDbus.Property{
Name: name,
Value: dbus.MakeVariant(units),
}
}
|
