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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2014-2015 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package systemd
import (
"errors"
"fmt"
"io"
"os"
"os/exec"
"path/filepath"
"regexp"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/snapcore/snapd/dirs"
"github.com/snapcore/snapd/osutil"
"github.com/snapcore/snapd/osutil/squashfs"
)
var (
// the output of "show" must match this for Stop to be done:
isStopDone = regexp.MustCompile(`(?m)\AActiveState=(?:failed|inactive)$`).Match
// how much time should Stop wait between calls to show
stopCheckDelay = 250 * time.Millisecond
// how much time should Stop wait between notifying the user of the waiting
stopNotifyDelay = 20 * time.Second
// daemonReloadLock is a package level lock to ensure that we
// do not run any `systemd daemon-reload` while a
// daemon-reload is in progress or a mount unit is
// generated/activated.
//
// See https://github.com/systemd/systemd/issues/10872 for the
// upstream systemd bug
daemonReloadLock extMutex
)
// mu is a sync.Mutex that also supports to check if the lock is taken
type extMutex struct {
lock sync.Mutex
muC int32
}
// Lock acquires the mutex
func (m *extMutex) Lock() {
m.lock.Lock()
atomic.AddInt32(&m.muC, 1)
}
// Unlock releases the mutex
func (m *extMutex) Unlock() {
m.lock.Unlock()
atomic.AddInt32(&m.muC, -1)
}
// Taken will panic with the given error message if the lock is not
// taken when this code runs. This is useful to internally check if
// something is accessed without a valid lock.
func (m *extMutex) Taken(errMsg string) {
if atomic.LoadInt32(&m.muC) != 1 {
panic("internal error: " + errMsg)
}
}
// systemctlCmd calls systemctl with the given args, returning its standard output (and wrapped error)
var systemctlCmd = func(args ...string) ([]byte, error) {
bs, err := exec.Command("systemctl", args...).CombinedOutput()
if err != nil {
exitCode, _ := osutil.ExitCode(err)
return nil, &Error{cmd: args, exitCode: exitCode, msg: bs}
}
return bs, nil
}
// MockSystemctl is called from the commands to actually call out to
// systemctl. It's exported so it can be overridden by testing.
func MockSystemctl(f func(args ...string) ([]byte, error)) func() {
oldSystemctlCmd := systemctlCmd
systemctlCmd = f
return func() {
systemctlCmd = oldSystemctlCmd
}
}
// MockStopDelays is used from tests so that Stop can be less
// forgiving there.
func MockStopDelays(checkDelay, notifyDelay time.Duration) func() {
oldCheckDelay := stopCheckDelay
oldNotifyDelay := stopNotifyDelay
stopCheckDelay = checkDelay
stopNotifyDelay = notifyDelay
return func() {
stopCheckDelay = oldCheckDelay
stopNotifyDelay = oldNotifyDelay
}
}
func Available() error {
_, err := systemctlCmd("--version")
return err
}
var osutilStreamCommand = osutil.StreamCommand
// jctl calls journalctl to get the JSON logs of the given services.
var jctl = func(svcs []string, n int, follow bool) (io.ReadCloser, error) {
// args will need two entries per service, plus a fixed number (give or take
// one) for the initial options.
args := make([]string, 0, 2*len(svcs)+6) // the fixed number is 6
args = append(args, "-o", "json", "--no-pager") // 3...
if n < 0 {
args = append(args, "--no-tail") // < 2
} else {
args = append(args, "-n", strconv.Itoa(n)) // ... + 2 ...
}
if follow {
args = append(args, "-f") // ... + 1 == 6
}
for i := range svcs {
args = append(args, "-u", svcs[i]) // this is why 2×
}
return osutilStreamCommand("journalctl", args...)
}
func MockJournalctl(f func(svcs []string, n int, follow bool) (io.ReadCloser, error)) func() {
oldJctl := jctl
jctl = f
return func() {
jctl = oldJctl
}
}
// Systemd exposes a minimal interface to manage systemd via the systemctl command.
type Systemd interface {
DaemonReload() error
Enable(service string) error
Disable(service string) error
Start(service ...string) error
StartNoBlock(service ...string) error
Stop(service string, timeout time.Duration) error
Kill(service, signal, who string) error
Restart(service string, timeout time.Duration) error
Status(units ...string) ([]*UnitStatus, error)
IsEnabled(service string) (bool, error)
IsActive(service string) (bool, error)
LogReader(services []string, n int, follow bool) (io.ReadCloser, error)
AddMountUnitFile(name, revision, what, where, fstype string) (string, error)
RemoveMountUnitFile(baseDir string) error
Mask(service string) error
Unmask(service string) error
}
// A Log is a single entry in the systemd journal
type Log map[string]string
const (
// the default target for systemd units that we generate
ServicesTarget = "multi-user.target"
// the target prerequisite for systemd units we generate
PrerequisiteTarget = "network.target"
// the default target for systemd socket units that we generate
SocketsTarget = "sockets.target"
// the default target for systemd timer units that we generate
TimersTarget = "timers.target"
)
type reporter interface {
Notify(string)
}
// New returns a Systemd that uses the given rootDir
func New(rootDir string, rep reporter) Systemd {
return &systemd{rootDir: rootDir, reporter: rep}
}
type systemd struct {
rootDir string
reporter reporter
}
// DaemonReload reloads systemd's configuration.
func (s *systemd) DaemonReload() error {
daemonReloadLock.Lock()
defer daemonReloadLock.Unlock()
return s.daemonReloadNoLock()
}
func (s *systemd) daemonReloadNoLock() error {
daemonReloadLock.Taken("cannot use daemon-reload without lock")
_, err := systemctlCmd("daemon-reload")
return err
}
// Enable the given service
func (s *systemd) Enable(serviceName string) error {
_, err := systemctlCmd("--root", s.rootDir, "enable", serviceName)
return err
}
// Unmask the given service
func (s *systemd) Unmask(serviceName string) error {
_, err := systemctlCmd("--root", s.rootDir, "unmask", serviceName)
return err
}
// Disable the given service
func (s *systemd) Disable(serviceName string) error {
_, err := systemctlCmd("--root", s.rootDir, "disable", serviceName)
return err
}
// Mask the given service
func (s *systemd) Mask(serviceName string) error {
_, err := systemctlCmd("--root", s.rootDir, "mask", serviceName)
return err
}
// Start the given service or services
func (*systemd) Start(serviceNames ...string) error {
_, err := systemctlCmd(append([]string{"start"}, serviceNames...)...)
return err
}
// StartNoBlock starts the given service or services non-blocking
func (*systemd) StartNoBlock(serviceNames ...string) error {
_, err := systemctlCmd(append([]string{"start", "--no-block"}, serviceNames...)...)
return err
}
// LogReader for the given services
func (*systemd) LogReader(serviceNames []string, n int, follow bool) (io.ReadCloser, error) {
return jctl(serviceNames, n, follow)
}
var statusregex = regexp.MustCompile(`(?m)^(?:(.+?)=(.*)|(.*))?$`)
type UnitStatus struct {
Daemon string
UnitName string
Enabled bool
Active bool
}
var baseProperties = []string{"Id", "ActiveState", "UnitFileState"}
var extendedProperties = []string{"Id", "ActiveState", "UnitFileState", "Type"}
var unitProperties = map[string][]string{
".timer": baseProperties,
".socket": baseProperties,
// in service units, Type is the daemon type
".service": extendedProperties,
// in mount units, Type is the fs type
".mount": extendedProperties,
}
// Status fetches the status of given units. Statuses are returned in the same
// order as unit names passed in argument.
func (s *systemd) Status(unitNames ...string) ([]*UnitStatus, error) {
cmd := make([]string, len(unitNames)+2)
cmd[0] = "show"
// ask for all properties, regardless of unit type
cmd[1] = "--property=" + strings.Join(extendedProperties, ",")
copy(cmd[2:], unitNames)
bs, err := systemctlCmd(cmd...)
if err != nil {
return nil, err
}
sts := make([]*UnitStatus, 0, len(unitNames))
cur := &UnitStatus{}
seen := map[string]bool{}
for _, bs := range statusregex.FindAllSubmatch(bs, -1) {
if len(bs[0]) == 0 {
// systemctl separates data pertaining to particular services by an empty line
unitType := filepath.Ext(cur.UnitName)
expected := unitProperties[unitType]
if expected == nil {
expected = baseProperties
}
missing := make([]string, 0, len(expected))
for _, k := range expected {
if !seen[k] {
missing = append(missing, k)
}
}
if len(missing) > 0 {
return nil, fmt.Errorf("cannot get unit %q status: missing %s in ‘systemctl show’ output", cur.UnitName, strings.Join(missing, ", "))
}
sts = append(sts, cur)
if len(sts) > len(unitNames) {
break // wut
}
if cur.UnitName != unitNames[len(sts)-1] {
return nil, fmt.Errorf("cannot get unit status: queried status of %q but got status of %q", unitNames[len(sts)-1], cur.UnitName)
}
cur = &UnitStatus{}
seen = map[string]bool{}
continue
}
if len(bs[3]) > 0 {
return nil, fmt.Errorf("cannot get unit status: bad line %q in ‘systemctl show’ output", bs[3])
}
k := string(bs[1])
v := string(bs[2])
if v == "" {
return nil, fmt.Errorf("cannot get unit status: empty field %q in ‘systemctl show’ output", k)
}
switch k {
case "Id":
cur.UnitName = v
case "Type":
cur.Daemon = v
case "ActiveState":
// made to match “systemctl is-active” behaviour, at least at systemd 229
cur.Active = v == "active" || v == "reloading"
case "UnitFileState":
// "static" means it can't be disabled
cur.Enabled = v == "enabled" || v == "static"
default:
return nil, fmt.Errorf("cannot get unit status: unexpected field %q in ‘systemctl show’ output", k)
}
if seen[k] {
return nil, fmt.Errorf("cannot get unit status: duplicate field %q in ‘systemctl show’ output", k)
}
seen[k] = true
}
if len(sts) != len(unitNames) {
return nil, fmt.Errorf("cannot get unit status: expected %d results, got %d", len(unitNames), len(sts))
}
return sts, nil
}
// IsEnabled checkes whether the given service is enabled
func (s *systemd) IsEnabled(serviceName string) (bool, error) {
_, err := systemctlCmd("--root", s.rootDir, "is-enabled", serviceName)
if err == nil {
return true, nil
}
// "systemctl is-enabled <name>" prints `disabled\n` to stderr and returns exit code 1
// for disabled services
sysdErr, ok := err.(*Error)
if ok && sysdErr.exitCode == 1 && strings.TrimSpace(string(sysdErr.msg)) == "disabled" {
return false, nil
}
return false, err
}
// IsActive checkes whether the given service is Active
func (s *systemd) IsActive(serviceName string) (bool, error) {
_, err := systemctlCmd("--root", s.rootDir, "is-active", serviceName)
if err == nil {
return true, nil
}
// "systemctl is-active <name>" prints `inactive\n` to stderr and returns exit code 1 for inactive services
sysdErr, ok := err.(*Error)
if ok && sysdErr.exitCode > 0 && strings.TrimSpace(string(sysdErr.msg)) == "inactive" {
return false, nil
}
return false, err
}
// Stop the given service, and wait until it has stopped.
func (s *systemd) Stop(serviceName string, timeout time.Duration) error {
if _, err := systemctlCmd("stop", serviceName); err != nil {
return err
}
// and now wait for it to actually stop
giveup := time.NewTimer(timeout)
notify := time.NewTicker(stopNotifyDelay)
defer notify.Stop()
check := time.NewTicker(stopCheckDelay)
defer check.Stop()
firstCheck := true
loop:
for {
select {
case <-giveup.C:
break loop
case <-check.C:
bs, err := systemctlCmd("show", "--property=ActiveState", serviceName)
if err != nil {
return err
}
if isStopDone(bs) {
return nil
}
if !firstCheck {
continue loop
}
firstCheck = false
case <-notify.C:
}
// after notify delay or after a failed first check
s.reporter.Notify(fmt.Sprintf("Waiting for %s to stop.", serviceName))
}
return &Timeout{action: "stop", service: serviceName}
}
// Kill all processes of the unit with the given signal
func (s *systemd) Kill(serviceName, signal, who string) error {
if who == "" {
who = "all"
}
_, err := systemctlCmd("kill", serviceName, "-s", signal, "--kill-who="+who)
return err
}
// Restart the service, waiting for it to stop before starting it again.
func (s *systemd) Restart(serviceName string, timeout time.Duration) error {
if err := s.Stop(serviceName, timeout); err != nil {
return err
}
return s.Start(serviceName)
}
// Error is returned if the systemd action failed
type Error struct {
cmd []string
msg []byte
exitCode int
}
func (e *Error) Error() string {
return fmt.Sprintf("%v failed with exit status %d: %s", e.cmd, e.exitCode, e.msg)
}
// Timeout is returned if the systemd action failed to reach the
// expected state in a reasonable amount of time
type Timeout struct {
action string
service string
}
func (e *Timeout) Error() string {
return fmt.Sprintf("%v failed to %v: timeout", e.service, e.action)
}
// IsTimeout checks whether the given error is a Timeout
func IsTimeout(err error) bool {
_, isTimeout := err.(*Timeout)
return isTimeout
}
// Time returns the time the Log was received by the journal.
func (l Log) Time() (time.Time, error) {
sus, ok := l["__REALTIME_TIMESTAMP"]
if !ok {
return time.Time{}, errors.New("no timestamp")
}
// according to systemd.journal-fields(7) it's microseconds as a decimal string
us, err := strconv.ParseInt(sus, 10, 64)
if err != nil {
return time.Time{}, fmt.Errorf("timestamp not a decimal number: %#v", sus)
}
return time.Unix(us/1000000, 1000*(us%1000000)).UTC(), nil
}
// Message of the Log, if any; otherwise, "-".
func (l Log) Message() string {
if msg, ok := l["MESSAGE"]; ok {
return msg
}
return "-"
}
// SID is the syslog identifier of the Log, if any; otherwise, "-".
func (l Log) SID() string {
if sid, ok := l["SYSLOG_IDENTIFIER"]; ok {
return sid
}
return "-"
}
// PID is the pid of the client pid, if any; otherwise, "-".
func (l Log) PID() string {
if pid, ok := l["_PID"]; ok {
return pid
}
if pid, ok := l["SYSLOG_PID"]; ok {
return pid
}
return "-"
}
// MountUnitPath returns the path of a {,auto}mount unit
func MountUnitPath(baseDir string) string {
escapedPath := EscapeUnitNamePath(baseDir)
return filepath.Join(dirs.SnapServicesDir, escapedPath+".mount")
}
// AddMountUnitFile adds/enables/starts a mount unit.
func (s *systemd) AddMountUnitFile(snapName, revision, what, where, fstype string) (string, error) {
daemonReloadLock.Lock()
defer daemonReloadLock.Unlock()
options := []string{"nodev"}
if fstype == "squashfs" {
newFsType, newOptions, err := squashfs.FsType()
if err != nil {
return "", err
}
options = append(options, newOptions...)
fstype = newFsType
}
if osutil.IsDirectory(what) {
options = append(options, "bind")
fstype = "none"
}
c := fmt.Sprintf(`[Unit]
Description=Mount unit for %s, revision %s
Before=snapd.service
[Mount]
What=%s
Where=%s
Type=%s
Options=%s
[Install]
WantedBy=multi-user.target
`, snapName, revision, what, where, fstype, strings.Join(options, ","))
mu := MountUnitPath(where)
mountUnitName, err := filepath.Base(mu), osutil.AtomicWriteFile(mu, []byte(c), 0644, 0)
if err != nil {
return "", err
}
// we need to do a daemon-reload here to ensure that systemd really
// knows about this new mount unit file
if err := s.daemonReloadNoLock(); err != nil {
return "", err
}
if err := s.Enable(mountUnitName); err != nil {
return "", err
}
if err := s.Start(mountUnitName); err != nil {
return "", err
}
return mountUnitName, nil
}
func (s *systemd) RemoveMountUnitFile(mountedDir string) error {
daemonReloadLock.Lock()
defer daemonReloadLock.Unlock()
unit := MountUnitPath(dirs.StripRootDir(mountedDir))
if !osutil.FileExists(unit) {
return nil
}
// use umount -d (cleanup loopback devices) -l (lazy) to ensure that even busy mount points
// can be unmounted.
// note that the long option --lazy is not supported on trusty.
// the explicit -d is only needed on trusty.
isMounted, err := osutil.IsMounted(mountedDir)
if err != nil {
return err
}
if isMounted {
if output, err := exec.Command("umount", "-d", "-l", mountedDir).CombinedOutput(); err != nil {
return osutil.OutputErr(output, err)
}
if err := s.Stop(filepath.Base(unit), time.Duration(1*time.Second)); err != nil {
return err
}
}
if err := s.Disable(filepath.Base(unit)); err != nil {
return err
}
if err := os.Remove(unit); err != nil {
return err
}
// daemon-reload to ensure that systemd actually really
// forgets about this mount unit
if err := s.daemonReloadNoLock(); err != nil {
return err
}
return nil
}
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