vendor c/psgo@v1.3.2

Now supports cgroupsv2.

Fixes: #4192
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

vendor/github.com/containers/psgo/internal/proc/pids.go

@@ -1,4 +1,4 @@
-// Copyright 2018 psgo authors
+// Copyright 2018-2019 psgo authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -18,8 +18,11 @@ import (
 	"bufio"
 	"fmt"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
+
+	"github.com/containers/psgo/internal/cgroups"
 )
 
 // GetPIDs extracts and returns all PIDs from /proc.
@@ -49,45 +52,98 @@ func GetPIDs() ([]string, error) {
 	return pids, nil
 }
 
-// pidCgroupPath returns the path to the pid's pids cgroup.
-func pidCgroupPath(pid string) (string, error) {
+// GetPIDsFromCgroup returns a strings slice of all pids listesd in pid's pids
+// cgroup.  It automatically detects if we're running in unified mode or not.
+func GetPIDsFromCgroup(pid string) ([]string, error) {
+	unified, err := cgroups.IsCgroup2UnifiedMode()
+	if err != nil {
+		return nil, err
+	}
+	if unified {
+		return getPIDsFromCgroupV2(pid)
+	}
+	return getPIDsFromCgroupV1(pid)
+}
+
+// getPIDsFromCgroupV1 returns a strings slice of all pids listesd in pid's pids
+// cgroup.
+func getPIDsFromCgroupV1(pid string) ([]string, error) {
+	// First, find the corresponding path to the PID cgroup.
 	f, err := os.Open(fmt.Sprintf("/proc/%s/cgroup", pid))
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	defer f.Close()
 
 	scanner := bufio.NewScanner(f)
+	cgroupPath := ""
 	for scanner.Scan() {
 		fields := strings.Split(scanner.Text(), ":")
 		if len(fields) != 3 {
 			continue
 		}
 		if fields[1] == "pids" {
-			return fmt.Sprintf("/sys/fs/cgroup/pids/%s/cgroup.procs", fields[2]), nil
+			cgroupPath = fmt.Sprintf("/sys/fs/cgroup/pids/%s/cgroup.procs", fields[2])
 		}
 	}
-	return "", fmt.Errorf("couldn't find pids group for PID %s", pid)
-}
 
-// GetPIDsFromCgroup returns a strings slice of all pids listesd in pid's pids
-// cgroup.
-func GetPIDsFromCgroup(pid string) ([]string, error) {
-	cgroupPath, err := pidCgroupPath(pid)
-	if err != nil {
-		return nil, err
+	if cgroupPath == "" {
+		return nil, fmt.Errorf("couldn't find v1 pids group for PID %s", pid)
 	}
 
-	f, err := os.Open(cgroupPath)
+	// Second, extract the PIDs inside the cgroup.
+	f, err = os.Open(cgroupPath)
 	if err != nil {
 		return nil, err
 	}
 	defer f.Close()
 
 	pids := []string{}
-	scanner := bufio.NewScanner(f)
+	scanner = bufio.NewScanner(f)
 	for scanner.Scan() {
 		pids = append(pids, scanner.Text())
 	}
+
+	return pids, nil
+}
+
+// getPIDsFromCgroupV2 returns a strings slice of all pids listesd in pid's pids
+// cgroup.
+func getPIDsFromCgroupV2(pid string) ([]string, error) {
+	// First, find the corresponding path to the PID cgroup.
+	f, err := os.Open(fmt.Sprintf("/proc/%s/cgroup", pid))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	cgroupSlice := ""
+	for scanner.Scan() {
+		fields := strings.Split(scanner.Text(), ":")
+		if len(fields) != 3 {
+			continue
+		}
+		cgroupSlice = fields[2]
+		break
+	}
+
+	if cgroupSlice == "" {
+		return nil, fmt.Errorf("couldn't find v2 pids group for PID %s", pid)
+	}
+
+	// Second, extract the PIDs inside the cgroup.
+	f, err = os.Open(filepath.Join(cgroups.CgroupRoot, cgroupSlice, "cgroup.procs"))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	pids := []string{}
+	scanner = bufio.NewScanner(f)
+	for scanner.Scan() {
+		pids = append(pids, scanner.Text())
+	}
+
 	return pids, nil
 }