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libcontainer/system/proc: Add Stat and Stat_t 

So we can extract more than the start time with a single read.

Signed-off-by: W. Trevor King <wking@tremily.us>
This commit is contained in:
W. Trevor King 2017-06-14 15:27:42 -07:00
parent c995ee407b
commit 439eaa3584
2 changed files with 33 additions and 10 deletions
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35
libcontainer/system/proc.go
View File

@ -1,23 +1,43 @@
package system package system
import ( import (
"fmt"
"io/ioutil" "io/ioutil"
"path/filepath" "path/filepath"
"strconv" "strconv"
"strings" "strings"
) )
// look in /proc to find the process start time so that we can verify // Stat_t represents the information from /proc/[pid]/stat, as
// that this pid has started after ourself // described in proc(5).
type Stat_t struct {
// 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
}
data := string(bytes)
stat.StartTime, err = parseStartTime(data)
return stat, err
}
// GetProcessStartTime is deprecated. Use Stat(pid) and
// Stat_t.StartTime instead.
func GetProcessStartTime(pid int) (string, error) { func GetProcessStartTime(pid int) (string, error) {
data, err := ioutil.ReadFile(filepath.Join("/proc", strconv.Itoa(pid), "stat")) stat, err := Stat(pid)
if err != nil { if err != nil {
return "", err return "", err
} }
return parseStartTime(string(data)) return fmt.Sprintf("%d", stat.StartTime), nil
} }
func parseStartTime(stat string) (string, error) { func parseStartTime(stat string) (uint64, error) {
// the starttime is located at pos 22 // the starttime is located at pos 22
// from the man page // from the man page
// //
@ -39,5 +59,8 @@ func parseStartTime(stat string) (string, error) {
// get parts after last `)`: // get parts after last `)`:
s := strings.Split(stat, ")") s := strings.Split(stat, ")")
parts := strings.Split(strings.TrimSpace(s[len(s)-1]), " ") parts := strings.Split(strings.TrimSpace(s[len(s)-1]), " ")
return parts[22-3], nil // starts at 3 (after the filename pos `2`) startTimeString := parts[22-3] // starts at 3 (after the filename pos `2`)
var startTime uint64
fmt.Sscanf(startTimeString, "%d", &startTime)
return startTime, nil
} }

8
libcontainer/system/proc_test.go
View File

@ -3,10 +3,10 @@ package system
import "testing" import "testing"
func TestParseStartTime(t *testing.T) { func TestParseStartTime(t *testing.T) {
data := map[string]string{ data := map[string]uint64{
"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": 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": "9214966", "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,
"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", "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,
} }
for line, startTime := range data { for line, startTime := range data {
st, err := parseStartTime(line) st, err := parseStartTime(line)