Merge pull request #1489 from wking/process-status

libcontainer/container_linux: Consider process state (running, zombie, etc.) in runType

libcontainer/container.go

@@ -54,7 +54,7 @@ type BaseState struct {
 	InitProcessPid int `json:"init_process_pid"`
 
 	// InitProcessStartTime is the init process start time in clock cycles since boot time.
-	InitProcessStartTime string `json:"init_process_start"`
+	InitProcessStartTime uint64 `json:"init_process_start"`
 
 	// Created is the unix timestamp for the creation time of the container in UTC
 	Created time.Time `json:"created"`

libcontainer/container_linux.go

@@ -40,7 +40,7 @@ type linuxContainer struct {
 	cgroupManager        cgroups.Manager
 	initArgs             []string
 	initProcess          parentProcess
-	initProcessStartTime string
+	initProcessStartTime uint64
 	criuPath             string
 	m                    sync.Mutex
 	criuVersion          int
@@ -1365,40 +1365,17 @@ func (c *linuxContainer) refreshState() error {
 	return c.state.transition(&stoppedState{c: c})
 }
 
-// doesInitProcessExist checks if the init process is still the same process
-// as the initial one, it could happen that the original process has exited
-// and a new process has been created with the same pid, in this case, the
-// container would already be stopped.
-func (c *linuxContainer) doesInitProcessExist(initPid int) (bool, error) {
-	startTime, err := system.GetProcessStartTime(initPid)
-	if err != nil {
-		return false, newSystemErrorWithCausef(err, "getting init process %d start time", initPid)
-	}
-	if c.initProcessStartTime != startTime {
-		return false, nil
-	}
-	return true, nil
-}
-
 func (c *linuxContainer) runType() (Status, error) {
 	if c.initProcess == nil {
 		return Stopped, nil
 	}
 	pid := c.initProcess.pid()
-	// return Running if the init process is alive
+	stat, err := system.Stat(pid)
-	if err := unix.Kill(pid, 0); err != nil {
+	if err != nil {
-		if err == unix.ESRCH {
+		return Stopped, nil
-			// It means the process does not exist anymore, could happen when the
-			// process exited just when we call the function, we should not return
-			// error in this case.
-			return Stopped, nil
-		}
-		return Stopped, newSystemErrorWithCausef(err, "sending signal 0 to pid %d", pid)
 	}
-	// check if the process is still the original init process.
+	if stat.StartTime != c.initProcessStartTime || stat.State == system.Zombie || stat.State == system.Dead {
-	exist, err := c.doesInitProcessExist(pid)
+		return Stopped, nil
-	if !exist || err != nil {
-		return Stopped, err
 	}
 	// We'll create exec fifo and blocking on it after container is created,
 	// and delete it after start container.
@@ -1427,7 +1404,7 @@ func (c *linuxContainer) isPaused() (bool, error) {
 
 func (c *linuxContainer) currentState() (*State, error) {
 	var (
-		startTime           string
+		startTime           uint64
 		externalDescriptors []string
 		pid                 = -1
 	)

libcontainer/container_linux_test.go

@@ -52,7 +52,7 @@ func (m *mockCgroupManager) Freeze(state configs.FreezerState) error {
 
 type mockProcess struct {
 	_pid    int
-	started string
+	started uint64
 }
 
 func (m *mockProcess) terminate() error {
@@ -63,7 +63,7 @@ func (m *mockProcess) pid() int {
 	return m._pid
 }
 
-func (m *mockProcess) startTime() (string, error) {
+func (m *mockProcess) startTime() (uint64, error) {
 	return m.started, nil
 }
 
@@ -150,7 +150,7 @@ func TestGetContainerState(t *testing.T) {
 		},
 		initProcess: &mockProcess{
 			_pid:    pid,
-			started: "010",
+			started: 10,
 		},
 		cgroupManager: &mockCgroupManager{
 			pids: []int{1, 2, 3},
@@ -174,8 +174,8 @@ func TestGetContainerState(t *testing.T) {
 	if state.InitProcessPid != pid {
 		t.Fatalf("expected pid %d but received %d", pid, state.InitProcessPid)
 	}
-	if state.InitProcessStartTime != "010" {
+	if state.InitProcessStartTime != 10 {
-		t.Fatalf("expected process start time 010 but received %s", state.InitProcessStartTime)
+		t.Fatalf("expected process start time 10 but received %d", state.InitProcessStartTime)
 	}
 	paths := state.CgroupPaths
 	if paths == nil {

libcontainer/integration/checkpoint_test.go

@@ -180,7 +180,7 @@ func testCheckpoint(t *testing.T, userns bool) {
 		t.Fatal(err)
 	}
 
-	if state != libcontainer.Running {
+	if state != libcontainer.Stopped {
 		t.Fatal("Unexpected state checkpoint: ", state)
 	}
 

libcontainer/process_linux.go

@@ -35,7 +35,7 @@ type parentProcess interface {
 	wait() (*os.ProcessState, error)
 
 	// startTime returns the process start time.
-	startTime() (string, error)
+	startTime() (uint64, error)
 
 	signal(os.Signal) error
 
@@ -55,8 +55,9 @@ type setnsProcess struct {
 	bootstrapData io.Reader
 }
 
-func (p *setnsProcess) startTime() (string, error) {
+func (p *setnsProcess) startTime() (uint64, error) {
-	return system.GetProcessStartTime(p.pid())
+	stat, err := system.Stat(p.pid())
+	return stat.StartTime, err
 }
 
 func (p *setnsProcess) signal(sig os.Signal) error {
@@ -384,8 +385,9 @@ func (p *initProcess) terminate() error {
 	return err
 }
 
-func (p *initProcess) startTime() (string, error) {
+func (p *initProcess) startTime() (uint64, error) {
-	return system.GetProcessStartTime(p.pid())
+	stat, err := system.Stat(p.pid())
+	return stat.StartTime, err
 }
 
 func (p *initProcess) sendConfig() error {

libcontainer/restored_process.go

@@ -17,20 +17,20 @@ func newRestoredProcess(pid int, fds []string) (*restoredProcess, error) {
 	if err != nil {
 		return nil, err
 	}
-	started, err := system.GetProcessStartTime(pid)
+	stat, err := system.Stat(pid)
 	if err != nil {
 		return nil, err
 	}
 	return &restoredProcess{
 		proc:             proc,
-		processStartTime: started,
+		processStartTime: stat.StartTime,
 		fds:              fds,
 	}, nil
 }
 
 type restoredProcess struct {
 	proc             *os.Process
-	processStartTime string
+	processStartTime uint64
 	fds              []string
 }
 
@@ -60,7 +60,7 @@ func (p *restoredProcess) wait() (*os.ProcessState, error) {
 	return st, nil
 }
 
-func (p *restoredProcess) startTime() (string, error) {
+func (p *restoredProcess) startTime() (uint64, error) {
 	return p.processStartTime, nil
 }
 
@@ -81,7 +81,7 @@ func (p *restoredProcess) setExternalDescriptors(newFds []string) {
 // a persisted state.
 type nonChildProcess struct {
 	processPid       int
-	processStartTime string
+	processStartTime uint64
 	fds              []string
 }
 
@@ -101,7 +101,7 @@ func (p *nonChildProcess) wait() (*os.ProcessState, error) {
 	return nil, newGenericError(fmt.Errorf("restored process cannot be waited on"), SystemError)
 }
 
-func (p *nonChildProcess) startTime() (string, error) {
+func (p *nonChildProcess) startTime() (uint64, error) {
 	return p.processStartTime, nil
 }
 

libcontainer/system/proc.go

@@ -1,43 +1,113 @@
 package system
 
 import (
+	"fmt"
 	"io/ioutil"
 	"path/filepath"
 	"strconv"
 	"strings"
 )
 
-// look in /proc to find the process start time so that we can verify
+// State is the status of a process.
-// that this pid has started after ourself
+type State rune
+
+const ( // Only values for Linux 3.14 and later are listed here
+	Dead        State = 'X'
+	DiskSleep   State = 'D'
+	Running     State = 'R'
+	Sleeping    State = 'S'
+	Stopped     State = 'T'
+	TracingStop State = 't'
+	Zombie      State = 'Z'
+)
+
+// String forms of the state from proc(5)'s documentation for
+// /proc/[pid]/status' "State" field.
+func (s State) String() string {
+	switch s {
+	case Dead:
+		return "dead"
+	case DiskSleep:
+		return "disk sleep"
+	case Running:
+		return "running"
+	case Sleeping:
+		return "sleeping"
+	case Stopped:
+		return "stopped"
+	case TracingStop:
+		return "tracing stop"
+	case Zombie:
+		return "zombie"
+	default:
+		return fmt.Sprintf("unknown (%c)", s)
+	}
+}
+
+// Stat_t represents the information from /proc/[pid]/stat, as
+// described in proc(5) with names based on the /proc/[pid]/status
+// fields.
+type Stat_t struct {
+	// PID is the process ID.
+	PID uint
+
+	// Name is the command run by the process.
+	Name string
+
+	// State is the state of the process.
+	State State
+
+	// StartTime is the number of clock ticks after system boot (since
+	// Linux 2.6).
+	StartTime uint64
+}
+
+// Stat returns a Stat_t instance for the specified process.
+func Stat(pid int) (stat Stat_t, err error) {
+	bytes, err := ioutil.ReadFile(filepath.Join("/proc", strconv.Itoa(pid), "stat"))
+	if err != nil {
+		return stat, err
+	}
+	return parseStat(string(bytes))
+}
+
+// GetProcessStartTime is deprecated.  Use Stat(pid) and
+// Stat_t.StartTime instead.
 func GetProcessStartTime(pid int) (string, error) {
-	data, err := ioutil.ReadFile(filepath.Join("/proc", strconv.Itoa(pid), "stat"))
+	stat, err := Stat(pid)
 	if err != nil {
 		return "", err
 	}
-	return parseStartTime(string(data))
+	return fmt.Sprintf("%d", stat.StartTime), nil
 }
 
-func parseStartTime(stat string) (string, error) {
+func parseStat(data string) (stat Stat_t, err error) {
-	// the starttime is located at pos 22
+	// From proc(5), field 2 could contain space and is inside `(` and `)`.
-	// from the man page
+	// The following is an example:
-	//
-	// starttime %llu (was %lu before Linux 2.6)
-	// (22)  The  time the process started after system boot.  In kernels before Linux 2.6, this
-	// value was expressed in jiffies.  Since Linux 2.6, the value is expressed in  clock  ticks
-	// (divide by sysconf(_SC_CLK_TCK)).
-	//
-	// NOTE:
-	// pos 2 could contain space and is inside `(` and `)`:
-	// (2) comm  %s
-	// The filename of the executable, in parentheses.
-	// This is visible whether or not the executable is
-	// swapped out.
-	//
-	// the following is an example:
 	// 89653 (gunicorn: maste) S 89630 89653 89653 0 -1 4194560 29689 28896 0 3 146 32 76 19 20 0 1 0 2971844 52965376 3920 18446744073709551615 1 1 0 0 0 0 0 16781312 137447943 0 0 0 17 1 0 0 0 0 0 0 0 0 0 0 0 0 0
+	i := strings.LastIndex(data, ")")
+	if i <= 2 || i >= len(data)-1 {
+		return stat, fmt.Errorf("invalid stat data: %q", data)
+	}
 
-	// get parts after last `)`:
+	parts := strings.SplitN(data[:i], "(", 2)
-	s := strings.Split(stat, ")")
+	if len(parts) != 2 {
-	parts := strings.Split(strings.TrimSpace(s[len(s)-1]), " ")
+		return stat, fmt.Errorf("invalid stat data: %q", data)
-	return parts[22-3], nil // starts at 3 (after the filename pos `2`)
+	}
+
+	stat.Name = parts[1]
+	_, err = fmt.Sscanf(parts[0], "%d", &stat.PID)
+	if err != nil {
+		return stat, err
+	}
+
+	// parts indexes should be offset by 3 from the field number given
+	// proc(5), because parts is zero-indexed and we've removed fields
+	// one (PID) and two (Name) in the paren-split.
+	parts = strings.Split(data[i+2:], " ")
+	var state int
+	fmt.Sscanf(parts[3-3], "%c", &state)
+	stat.State = State(state)
+	fmt.Sscanf(parts[22-3], "%d", &stat.StartTime)
+	return stat, nil
 }

libcontainer/system/proc_test.go

@@ -3,18 +3,43 @@ package system
 import "testing"
 
 func TestParseStartTime(t *testing.T) {
-	data := map[string]string{
+	data := map[string]Stat_t{
-		"4902 (gunicorn: maste) S 4885 4902 4902 0 -1 4194560 29683 29929 61 83 78 16 96 17 20 0 1 0 9126532 52965376 1903 18446744073709551615 4194304 7461796 140733928751520 140733928698072 139816984959091 0 0 16781312 137447943 1 0 0 17 3 0 0 9 0 0 9559488 10071156 33050624 140733928758775 140733928758945 140733928758945 140733928759264 0": "9126532",
+		"4902 (gunicorn: maste) S 4885 4902 4902 0 -1 4194560 29683 29929 61 83 78 16 96 17 20 0 1 0 9126532 52965376 1903 18446744073709551615 4194304 7461796 140733928751520 140733928698072 139816984959091 0 0 16781312 137447943 1 0 0 17 3 0 0 9 0 0 9559488 10071156 33050624 140733928758775 140733928758945 140733928758945 140733928759264 0": {
-		"9534 (cat) R 9323 9534 9323 34828 9534 4194304 95 0 0 0 0 0 0 0 20 0 1 0 9214966 7626752 168 18446744073709551615 4194304 4240332 140732237651568 140732237650920 140570710391216 0 0 0 0 0 0 0 17 1 0 0 0 0 0 6340112 6341364 21553152 140732237653865 140732237653885 140732237653885 140732237656047 0":                                      "9214966",
+			PID:       4902,
-		"24767 (irq/44-mei_me) S 2 0 0 0 -1 2129984 0 0 0 0 0 0 0 0 -51 0 1 0 8722075 0 0 18446744073709551615 0 0 0 0 0 0 0 2147483647 0 0 0 0 17 1 50 1 0 0 0 0 0 0 0 0 0 0 0":                                                                                                                                                                         "8722075",
+			Name:      "gunicorn: maste",
+			State:     'S',
+			StartTime: 9126532,
+		},
+		"9534 (cat) R 9323 9534 9323 34828 9534 4194304 95 0 0 0 0 0 0 0 20 0 1 0 9214966 7626752 168 18446744073709551615 4194304 4240332 140732237651568 140732237650920 140570710391216 0 0 0 0 0 0 0 17 1 0 0 0 0 0 6340112 6341364 21553152 140732237653865 140732237653885 140732237653885 140732237656047 0": {
+			PID:       9534,
+			Name:      "cat",
+			State:     'R',
+			StartTime: 9214966,
+		},
+
+		"24767 (irq/44-mei_me) S 2 0 0 0 -1 2129984 0 0 0 0 0 0 0 0 -51 0 1 0 8722075 0 0 18446744073709551615 0 0 0 0 0 0 0 2147483647 0 0 0 0 17 1 50 1 0 0 0 0 0 0 0 0 0 0 0": {
+			PID:       24767,
+			Name:      "irq/44-mei_me",
+			State:     'S',
+			StartTime: 8722075,
+		},
 	}
-	for line, startTime := range data {
+	for line, expected := range data {
-		st, err := parseStartTime(line)
+		st, err := parseStat(line)
 		if err != nil {
 			t.Fatal(err)
 		}
-		if startTime != st {
+		if st.PID != expected.PID {
-			t.Fatalf("expected start time %q but received %q", startTime, st)
+			t.Fatalf("expected PID %q but received %q", expected.PID, st.PID)
+		}
+		if st.State != expected.State {
+			t.Fatalf("expected state %q but received %q", expected.State, st.State)
+		}
+		if st.Name != expected.Name {
+			t.Fatalf("expected name %q but received %q", expected.Name, st.Name)
+		}
+		if st.StartTime != expected.StartTime {
+			t.Fatalf("expected start time %q but received %q", expected.StartTime, st.StartTime)
 		}
 	}
 }