libcontainer/cgroups/utils.go - external/github.com/docker/runc - Git at Google

 // +build linux

 package cgroups

 import (
 	"bufio"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"time"

 	"github.com/docker/go-units"
 )

 const (
 	cgroupNamePrefix = "name="
 	CgroupProcesses  = "cgroup.procs"
 )

 // https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt
 func FindCgroupMountpoint(subsystem string) (string, error) {
 	// We are not using mount.GetMounts() because it's super-inefficient,
 	// parsing it directly sped up x10 times because of not using Sscanf.
 	// It was one of two major performance drawbacks in container start.
 	if !isSubsystemAvailable(subsystem) {
 		return "", NewNotFoundError(subsystem)
 	}
 	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
 		return "", err
 	}
 	defer f.Close()

 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {
 		txt := scanner.Text()
 		fields := strings.Split(txt, " ")
 		for _, opt := range strings.Split(fields[len(fields)-1], ",") {
 			if opt == subsystem {
 				return fields[4], nil
 			}
 		}
 	}
 	if err := scanner.Err(); err != nil {
 		return "", err
 	}

 	return "", NewNotFoundError(subsystem)
 }

 func FindCgroupMountpointAndRoot(subsystem string) (string, string, error) {
 	if !isSubsystemAvailable(subsystem) {
 		return "", "", NewNotFoundError(subsystem)
 	}
 	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
 		return "", "", err
 	}
 	defer f.Close()

 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {
 		txt := scanner.Text()
 		fields := strings.Split(txt, " ")
 		for _, opt := range strings.Split(fields[len(fields)-1], ",") {
 			if opt == subsystem {
 				return fields[4], fields[3], nil
 			}
 		}
 	}
 	if err := scanner.Err(); err != nil {
 		return "", "", err
 	}

 	return "", "", NewNotFoundError(subsystem)
 }

 func isSubsystemAvailable(subsystem string) bool {
 	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
 		return false
 	}
 	_, avail := cgroups[subsystem]
 	return avail
 }

 func FindCgroupMountpointDir() (string, error) {
 	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
 		return "", err
 	}
 	defer f.Close()

 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {
 		text := scanner.Text()
 		fields := strings.Split(text, " ")
 		// Safe as mountinfo encodes mountpoints with spaces as \040.
 		index := strings.Index(text, " - ")
 		postSeparatorFields := strings.Fields(text[index+3:])
 		numPostFields := len(postSeparatorFields)

 		// This is an error as we can't detect if the mount is for "cgroup"
 		if numPostFields == 0 {
 			return "", fmt.Errorf("Found no fields post '-' in %q", text)
 		}

 		if postSeparatorFields[0] == "cgroup" {
 			// Check that the mount is properly formated.
 			if numPostFields < 3 {
 				return "", fmt.Errorf("Error found less than 3 fields post '-' in %q", text)
 			}

 			return filepath.Dir(fields[4]), nil
 		}
 	}
 	if err := scanner.Err(); err != nil {
 		return "", err
 	}

 	return "", NewNotFoundError("cgroup")
 }

 type Mount struct {
 	Mountpoint string
 	Root       string
 	Subsystems []string
 }

 func (m Mount) GetThisCgroupDir(cgroups map[string]string) (string, error) {
 	if len(m.Subsystems) == 0 {
 		return "", fmt.Errorf("no subsystem for mount")
 	}

 	return getControllerPath(m.Subsystems[0], cgroups)
 }

 func getCgroupMountsHelper(ss map[string]bool, mi io.Reader, all bool) ([]Mount, error) {
 	res := make([]Mount, 0, len(ss))
 	scanner := bufio.NewScanner(mi)
 	numFound := 0
 	for scanner.Scan() && numFound < len(ss) {
 		txt := scanner.Text()
 		sepIdx := strings.Index(txt, " - ")
 		if sepIdx == -1 {
 			return nil, fmt.Errorf("invalid mountinfo format")
 		}
 		if txt[sepIdx+3:sepIdx+9] != "cgroup" {
 			continue
 		}
 		fields := strings.Split(txt, " ")
 		m := Mount{
 			Mountpoint: fields[4],
 			Root:       fields[3],
 		}
 		for _, opt := range strings.Split(fields[len(fields)-1], ",") {
 			if !ss[opt] {
 				continue
 			}
 			if strings.HasPrefix(opt, cgroupNamePrefix) {
 				m.Subsystems = append(m.Subsystems, opt[len(cgroupNamePrefix):])
 			} else {
 				m.Subsystems = append(m.Subsystems, opt)
 			}
 			if !all {
 				numFound++
 			}
 		}
 		res = append(res, m)
 	}
 	if err := scanner.Err(); err != nil {
 		return nil, err
 	}
 	return res, nil
 }

 // GetCgroupMounts returns the mounts for the cgroup subsystems.
 // all indicates whether to return just the first instance or all the mounts.
 func GetCgroupMounts(all bool) ([]Mount, error) {
 	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
 		return nil, err
 	}
 	defer f.Close()

 	allSubsystems, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
 		return nil, err
 	}

 	allMap := make(map[string]bool)
 	for s := range allSubsystems {
 		allMap[s] = true
 	}
 	return getCgroupMountsHelper(allMap, f, all)
 }

 // GetAllSubsystems returns all the cgroup subsystems supported by the kernel
 func GetAllSubsystems() ([]string, error) {
 	f, err := os.Open("/proc/cgroups")
 	if err != nil {
 		return nil, err
 	}
 	defer f.Close()

 	subsystems := []string{}

 	s := bufio.NewScanner(f)
 	for s.Scan() {
 		if err := s.Err(); err != nil {
 			return nil, err
 		}
 		text := s.Text()
 		if text[0] != '#' {
 			parts := strings.Fields(text)
 			if len(parts) >= 4 && parts[3] != "0" {
 				subsystems = append(subsystems, parts[0])
 			}
 		}
 	}
 	return subsystems, nil
 }

 // GetThisCgroupDir returns the relative path to the cgroup docker is running in.
 func GetThisCgroupDir(subsystem string) (string, error) {
 	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
 		return "", err
 	}

 	return getControllerPath(subsystem, cgroups)
 }

 func GetInitCgroupDir(subsystem string) (string, error) {

 	cgroups, err := ParseCgroupFile("/proc/1/cgroup")
 	if err != nil {
 		return "", err
 	}

 	return getControllerPath(subsystem, cgroups)
 }

 func readProcsFile(dir string) ([]int, error) {
 	f, err := os.Open(filepath.Join(dir, CgroupProcesses))
 	if err != nil {
 		return nil, err
 	}
 	defer f.Close()

 	var (
 		s   = bufio.NewScanner(f)
 		out = []int{}
 	)

 	for s.Scan() {
 		if t := s.Text(); t != "" {
 			pid, err := strconv.Atoi(t)
 			if err != nil {
 				return nil, err
 			}
 			out = append(out, pid)
 		}
 	}
 	return out, nil
 }

 // ParseCgroupFile parses the given cgroup file, typically from
 // /proc/<pid>/cgroup, into a map of subgroups to cgroup names.
 func ParseCgroupFile(path string) (map[string]string, error) {
 	f, err := os.Open(path)
 	if err != nil {
 		return nil, err
 	}
 	defer f.Close()

 	return parseCgroupFromReader(f)
 }

 // helper function for ParseCgroupFile to make testing easier
 func parseCgroupFromReader(r io.Reader) (map[string]string, error) {
 	s := bufio.NewScanner(r)
 	cgroups := make(map[string]string)

 	for s.Scan() {
 		if err := s.Err(); err != nil {
 			return nil, err
 		}

 		text := s.Text()
 		// from cgroups(7):
 		// /proc/[pid]/cgroup
 		// ...
 		// For each cgroup hierarchy ... there is one entry
 		// containing three colon-separated fields of the form:
 		//     hierarchy-ID:subsystem-list:cgroup-path
 		parts := strings.SplitN(text, ":", 3)
 		if len(parts) < 3 {
 			return nil, fmt.Errorf("invalid cgroup entry: must contain at least two colons: %v", text)
 		}

 		for _, subs := range strings.Split(parts[1], ",") {
 			cgroups[subs] = parts[2]
 		}
 	}
 	return cgroups, nil
 }

 func getControllerPath(subsystem string, cgroups map[string]string) (string, error) {

 	if p, ok := cgroups[subsystem]; ok {
 		return p, nil
 	}

 	if p, ok := cgroups[cgroupNamePrefix+subsystem]; ok {
 		return p, nil
 	}

 	return "", NewNotFoundError(subsystem)
 }

 func PathExists(path string) bool {
 	if _, err := os.Stat(path); err != nil {
 		return false
 	}
 	return true
 }

 func EnterPid(cgroupPaths map[string]string, pid int) error {
 	for _, path := range cgroupPaths {
 		if PathExists(path) {
 			if err := WriteCgroupProc(path, pid); err != nil {
 				return err
 			}
 		}
 	}
 	return nil
 }

 // RemovePaths iterates over the provided paths removing them.
 // We trying to remove all paths five times with increasing delay between tries.
 // If after all there are not removed cgroups - appropriate error will be
 // returned.
 func RemovePaths(paths map[string]string) (err error) {
 	delay := 10 * time.Millisecond
 	for i := 0; i < 5; i++ {
 		if i != 0 {
 			time.Sleep(delay)
 			delay *= 2
 		}
 		for s, p := range paths {
 			os.RemoveAll(p)
 			// TODO: here probably should be logging
 			_, err := os.Stat(p)
 			// We need this strange way of checking cgroups existence because
 			// RemoveAll almost always returns error, even on already removed
 			// cgroups
 			if os.IsNotExist(err) {
 				delete(paths, s)
 			}
 		}
 		if len(paths) == 0 {
 			return nil
 		}
 	}
 	return fmt.Errorf("Failed to remove paths: %v", paths)
 }

 func GetHugePageSize() ([]string, error) {
 	var pageSizes []string
 	sizeList := []string{"B", "kB", "MB", "GB", "TB", "PB"}
 	files, err := ioutil.ReadDir("/sys/kernel/mm/hugepages")
 	if err != nil {
 		return pageSizes, err
 	}
 	for _, st := range files {
 		nameArray := strings.Split(st.Name(), "-")
 		pageSize, err := units.RAMInBytes(nameArray[1])
 		if err != nil {
 			return []string{}, err
 		}
 		sizeString := units.CustomSize("%g%s", float64(pageSize), 1024.0, sizeList)
 		pageSizes = append(pageSizes, sizeString)
 	}

 	return pageSizes, nil
 }

 // GetPids returns all pids, that were added to cgroup at path.
 func GetPids(path string) ([]int, error) {
 	return readProcsFile(path)
 }

 // GetAllPids returns all pids, that were added to cgroup at path and to all its
 // subcgroups.
 func GetAllPids(path string) ([]int, error) {
 	var pids []int
 	// collect pids from all sub-cgroups
 	err := filepath.Walk(path, func(p string, info os.FileInfo, iErr error) error {
 		dir, file := filepath.Split(p)
 		if file != CgroupProcesses {
 			return nil
 		}
 		if iErr != nil {
 			return iErr
 		}
 		cPids, err := readProcsFile(dir)
 		if err != nil {
 			return err
 		}
 		pids = append(pids, cPids...)
 		return nil
 	})
 	return pids, err
 }

 // WriteCgroupProc writes the specified pid into the cgroup's cgroup.procs file
 func WriteCgroupProc(dir string, pid int) error {
 	// Normally dir should not be empty, one case is that cgroup subsystem
 	// is not mounted, we will get empty dir, and we want it fail here.
 	if dir == "" {
 		return fmt.Errorf("no such directory for %s", CgroupProcesses)
 	}

 	// Dont attach any pid to the cgroup if -1 is specified as a pid
 	if pid != -1 {
 		if err := ioutil.WriteFile(filepath.Join(dir, CgroupProcesses), []byte(strconv.Itoa(pid)), 0700); err != nil {
 			return fmt.Errorf("failed to write %v to %v: %v", pid, CgroupProcesses, err)
 		}
 	}
 	return nil
 }
	// +build linux

	package cgroups

	import (
	"bufio"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/docker/go-units"
	)

	const (
	cgroupNamePrefix = "name="
	CgroupProcesses = "cgroup.procs"
	)

	// https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt
	func FindCgroupMountpoint(subsystem string) (string, error) {
	// We are not using mount.GetMounts() because it's super-inefficient,
	// parsing it directly sped up x10 times because of not using Sscanf.
	// It was one of two major performance drawbacks in container start.
	if !isSubsystemAvailable(subsystem) {
	return "", NewNotFoundError(subsystem)
	}
	f, err := os.Open("/proc/self/mountinfo")
	if err != nil {
	return "", err
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
	txt := scanner.Text()
	fields := strings.Split(txt, " ")
	for _, opt := range strings.Split(fields[len(fields)-1], ",") {
	if opt == subsystem {
	return fields[4], nil
	}
	}
	}
	if err := scanner.Err(); err != nil {
	return "", err
	}

	return "", NewNotFoundError(subsystem)
	}

	func FindCgroupMountpointAndRoot(subsystem string) (string, string, error) {
	if !isSubsystemAvailable(subsystem) {
	return "", "", NewNotFoundError(subsystem)
	}
	f, err := os.Open("/proc/self/mountinfo")
	if err != nil {
	return "", "", err
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
	txt := scanner.Text()
	fields := strings.Split(txt, " ")
	for _, opt := range strings.Split(fields[len(fields)-1], ",") {
	if opt == subsystem {
	return fields[4], fields[3], nil
	}
	}
	}
	if err := scanner.Err(); err != nil {
	return "", "", err
	}

	return "", "", NewNotFoundError(subsystem)
	}

	func isSubsystemAvailable(subsystem string) bool {
	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
	if err != nil {
	return false
	}
	_, avail := cgroups[subsystem]
	return avail
	}

	func FindCgroupMountpointDir() (string, error) {
	f, err := os.Open("/proc/self/mountinfo")
	if err != nil {
	return "", err
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
	text := scanner.Text()
	fields := strings.Split(text, " ")
	// Safe as mountinfo encodes mountpoints with spaces as \040.
	index := strings.Index(text, " - ")
	postSeparatorFields := strings.Fields(text[index+3:])
	numPostFields := len(postSeparatorFields)

	// This is an error as we can't detect if the mount is for "cgroup"
	if numPostFields == 0 {
	return "", fmt.Errorf("Found no fields post '-' in %q", text)
	}

	if postSeparatorFields[0] == "cgroup" {
	// Check that the mount is properly formated.
	if numPostFields < 3 {
	return "", fmt.Errorf("Error found less than 3 fields post '-' in %q", text)
	}

	return filepath.Dir(fields[4]), nil
	}
	}
	if err := scanner.Err(); err != nil {
	return "", err
	}

	return "", NewNotFoundError("cgroup")
	}

	type Mount struct {
	Mountpoint string
	Root string
	Subsystems []string
	}

	func (m Mount) GetThisCgroupDir(cgroups map[string]string) (string, error) {
	if len(m.Subsystems) == 0 {
	return "", fmt.Errorf("no subsystem for mount")
	}

	return getControllerPath(m.Subsystems[0], cgroups)
	}

	func getCgroupMountsHelper(ss map[string]bool, mi io.Reader, all bool) ([]Mount, error) {
	res := make([]Mount, 0, len(ss))
	scanner := bufio.NewScanner(mi)
	numFound := 0
	for scanner.Scan() && numFound < len(ss) {
	txt := scanner.Text()
	sepIdx := strings.Index(txt, " - ")
	if sepIdx == -1 {
	return nil, fmt.Errorf("invalid mountinfo format")
	}
	if txt[sepIdx+3:sepIdx+9] != "cgroup" {
	continue
	}
	fields := strings.Split(txt, " ")
	m := Mount{
	Mountpoint: fields[4],
	Root: fields[3],
	}
	for _, opt := range strings.Split(fields[len(fields)-1], ",") {
	if !ss[opt] {
	continue
	}
	if strings.HasPrefix(opt, cgroupNamePrefix) {
	m.Subsystems = append(m.Subsystems, opt[len(cgroupNamePrefix):])
	} else {
	m.Subsystems = append(m.Subsystems, opt)
	}
	if !all {
	numFound++
	}
	}
	res = append(res, m)
	}
	if err := scanner.Err(); err != nil {
	return nil, err
	}
	return res, nil
	}

	// GetCgroupMounts returns the mounts for the cgroup subsystems.
	// all indicates whether to return just the first instance or all the mounts.
	func GetCgroupMounts(all bool) ([]Mount, error) {
	f, err := os.Open("/proc/self/mountinfo")
	if err != nil {
	return nil, err
	}
	defer f.Close()

	allSubsystems, err := ParseCgroupFile("/proc/self/cgroup")
	if err != nil {
	return nil, err
	}

	allMap := make(map[string]bool)
	for s := range allSubsystems {
	allMap[s] = true
	}
	return getCgroupMountsHelper(allMap, f, all)
	}

	// GetAllSubsystems returns all the cgroup subsystems supported by the kernel
	func GetAllSubsystems() ([]string, error) {
	f, err := os.Open("/proc/cgroups")
	if err != nil {
	return nil, err
	}
	defer f.Close()

	subsystems := []string{}

	s := bufio.NewScanner(f)
	for s.Scan() {
	if err := s.Err(); err != nil {
	return nil, err
	}
	text := s.Text()
	if text[0] != '#' {
	parts := strings.Fields(text)
	if len(parts) >= 4 && parts[3] != "0" {
	subsystems = append(subsystems, parts[0])
	}
	}
	}
	return subsystems, nil
	}

	// GetThisCgroupDir returns the relative path to the cgroup docker is running in.
	func GetThisCgroupDir(subsystem string) (string, error) {
	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
	if err != nil {
	return "", err
	}

	return getControllerPath(subsystem, cgroups)
	}

	func GetInitCgroupDir(subsystem string) (string, error) {

	cgroups, err := ParseCgroupFile("/proc/1/cgroup")
	if err != nil {
	return "", err
	}

	return getControllerPath(subsystem, cgroups)
	}

	func readProcsFile(dir string) ([]int, error) {
	f, err := os.Open(filepath.Join(dir, CgroupProcesses))
	if err != nil {
	return nil, err
	}
	defer f.Close()

	var (
	s = bufio.NewScanner(f)
	out = []int{}
	)

	for s.Scan() {
	if t := s.Text(); t != "" {
	pid, err := strconv.Atoi(t)
	if err != nil {
	return nil, err
	}
	out = append(out, pid)
	}
	}
	return out, nil
	}

	// ParseCgroupFile parses the given cgroup file, typically from
	// /proc/<pid>/cgroup, into a map of subgroups to cgroup names.
	func ParseCgroupFile(path string) (map[string]string, error) {
	f, err := os.Open(path)
	if err != nil {
	return nil, err
	}
	defer f.Close()

	return parseCgroupFromReader(f)
	}

	// helper function for ParseCgroupFile to make testing easier
	func parseCgroupFromReader(r io.Reader) (map[string]string, error) {
	s := bufio.NewScanner(r)
	cgroups := make(map[string]string)

	for s.Scan() {
	if err := s.Err(); err != nil {
	return nil, err
	}

	text := s.Text()
	// from cgroups(7):
	// /proc/[pid]/cgroup
	// ...
	// For each cgroup hierarchy ... there is one entry
	// containing three colon-separated fields of the form:
	// hierarchy-ID:subsystem-list:cgroup-path
	parts := strings.SplitN(text, ":", 3)
	if len(parts) < 3 {
	return nil, fmt.Errorf("invalid cgroup entry: must contain at least two colons: %v", text)
	}

	for _, subs := range strings.Split(parts[1], ",") {
	cgroups[subs] = parts[2]
	}
	}
	return cgroups, nil
	}

	func getControllerPath(subsystem string, cgroups map[string]string) (string, error) {

	if p, ok := cgroups[subsystem]; ok {
	return p, nil
	}

	if p, ok := cgroups[cgroupNamePrefix+subsystem]; ok {
	return p, nil
	}

	return "", NewNotFoundError(subsystem)
	}

	func PathExists(path string) bool {
	if _, err := os.Stat(path); err != nil {
	return false
	}
	return true
	}

	func EnterPid(cgroupPaths map[string]string, pid int) error {
	for _, path := range cgroupPaths {
	if PathExists(path) {
	if err := WriteCgroupProc(path, pid); err != nil {
	return err
	}
	}
	}
	return nil
	}

	// RemovePaths iterates over the provided paths removing them.
	// We trying to remove all paths five times with increasing delay between tries.
	// If after all there are not removed cgroups - appropriate error will be
	// returned.
	func RemovePaths(paths map[string]string) (err error) {
	delay := 10 * time.Millisecond
	for i := 0; i < 5; i++ {
	if i != 0 {
	time.Sleep(delay)
	delay *= 2
	}
	for s, p := range paths {
	os.RemoveAll(p)
	// TODO: here probably should be logging
	_, err := os.Stat(p)
	// We need this strange way of checking cgroups existence because
	// RemoveAll almost always returns error, even on already removed
	// cgroups
	if os.IsNotExist(err) {
	delete(paths, s)
	}
	}
	if len(paths) == 0 {
	return nil
	}
	}
	return fmt.Errorf("Failed to remove paths: %v", paths)
	}

	func GetHugePageSize() ([]string, error) {
	var pageSizes []string
	sizeList := []string{"B", "kB", "MB", "GB", "TB", "PB"}
	files, err := ioutil.ReadDir("/sys/kernel/mm/hugepages")
	if err != nil {
	return pageSizes, err
	}
	for _, st := range files {
	nameArray := strings.Split(st.Name(), "-")
	pageSize, err := units.RAMInBytes(nameArray[1])
	if err != nil {
	return []string{}, err
	}
	sizeString := units.CustomSize("%g%s", float64(pageSize), 1024.0, sizeList)
	pageSizes = append(pageSizes, sizeString)
	}

	return pageSizes, nil
	}

	// GetPids returns all pids, that were added to cgroup at path.
	func GetPids(path string) ([]int, error) {
	return readProcsFile(path)
	}

	// GetAllPids returns all pids, that were added to cgroup at path and to all its
	// subcgroups.
	func GetAllPids(path string) ([]int, error) {
	var pids []int
	// collect pids from all sub-cgroups
	err := filepath.Walk(path, func(p string, info os.FileInfo, iErr error) error {
	dir, file := filepath.Split(p)
	if file != CgroupProcesses {
	return nil
	}
	if iErr != nil {
	return iErr
	}
	cPids, err := readProcsFile(dir)
	if err != nil {
	return err
	}
	pids = append(pids, cPids...)
	return nil
	})
	return pids, err
	}

	// WriteCgroupProc writes the specified pid into the cgroup's cgroup.procs file
	func WriteCgroupProc(dir string, pid int) error {
	// Normally dir should not be empty, one case is that cgroup subsystem
	// is not mounted, we will get empty dir, and we want it fail here.
	if dir == "" {
	return fmt.Errorf("no such directory for %s", CgroupProcesses)
	}

	// Dont attach any pid to the cgroup if -1 is specified as a pid
	if pid != -1 {
	if err := ioutil.WriteFile(filepath.Join(dir, CgroupProcesses), []byte(strconv.Itoa(pid)), 0700); err != nil {
	return fmt.Errorf("failed to write %v to %v: %v", pid, CgroupProcesses, err)
	}
	}
	return nil
	}