1 files changed, 250 insertions, 0 deletions
diff --git a/vendor/github.com/opencontainers/runc/libcontainer/cgroups/v1_utils.go b/vendor/github.com/opencontainers/runc/libcontainer/cgroups/v1_utils.go
new file mode 100644
index 000000000..f8487b0a9
--- /dev/null
+++ b/vendor/github.com/opencontainers/runc/libcontainer/cgroups/v1_utils.go
@@ -0,0 +1,250 @@
+package cgroups
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// Code in this source file are specific to cgroup v1,
+// and must not be used from any cgroup v2 code.
+
+const (
+	CgroupNamePrefix = "name="
+)
+
+var (
+	errUnified = errors.New("not implemented for cgroup v2 unified hierarchy")
+)
+
+type NotFoundError struct {
+	Subsystem string
+}
+
+func (e *NotFoundError) Error() string {
+	return fmt.Sprintf("mountpoint for %s not found", e.Subsystem)
+}
+
+func NewNotFoundError(sub string) error {
+	return &NotFoundError{
+		Subsystem: sub,
+	}
+}
+
+func IsNotFound(err error) bool {
+	if err == nil {
+		return false
+	}
+	_, ok := err.(*NotFoundError)
+	return ok
+}
+
+// https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt
+func FindCgroupMountpoint(cgroupPath, subsystem string) (string, error) {
+	if IsCgroup2UnifiedMode() {
+		return "", errUnified
+	}
+	mnt, _, err := FindCgroupMountpointAndRoot(cgroupPath, subsystem)
+	return mnt, err
+}
+
+func FindCgroupMountpointAndRoot(cgroupPath, subsystem string) (string, string, error) {
+	if IsCgroup2UnifiedMode() {
+		return "", "", errUnified
+	}
+
+	// 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()
+
+	return findCgroupMountpointAndRootFromReader(f, cgroupPath, subsystem)
+}
+
+func findCgroupMountpointAndRootFromReader(reader io.Reader, cgroupPath, subsystem string) (string, string, error) {
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		txt := scanner.Text()
+		fields := strings.Fields(txt)
+		if len(fields) < 9 {
+			continue
+		}
+		if strings.HasPrefix(fields[4], cgroupPath) {
+			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 {
+	if IsCgroup2UnifiedMode() {
+		panic("don't call isSubsystemAvailable from cgroupv2 code")
+	}
+
+	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
+	if err != nil {
+		return false
+	}
+	_, avail := cgroups[subsystem]
+	return avail
+}
+
+func (m Mount) GetOwnCgroup(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+10] == "cgroup2" || 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], ",") {
+			seen, known := ss[opt]
+			if !known || (!all && seen) {
+				continue
+			}
+			ss[opt] = true
+			opt = strings.TrimPrefix(opt, CgroupNamePrefix)
+			m.Subsystems = append(m.Subsystems, opt)
+			numFound++
+		}
+		if len(m.Subsystems) > 0 || all {
+			res = append(res, m)
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+	return res, nil
+}
+
+func getCgroupMountsV1(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] = false
+	}
+	return getCgroupMountsHelper(allMap, f, all)
+}
+
+// GetOwnCgroup returns the relative path to the cgroup docker is running in.
+func GetOwnCgroup(subsystem string) (string, error) {
+	if IsCgroup2UnifiedMode() {
+		return "", errUnified
+	}
+	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
+	if err != nil {
+		return "", err
+	}
+
+	return getControllerPath(subsystem, cgroups)
+}
+
+func GetOwnCgroupPath(subsystem string) (string, error) {
+	cgroup, err := GetOwnCgroup(subsystem)
+	if err != nil {
+		return "", err
+	}
+
+	return getCgroupPathHelper(subsystem, cgroup)
+}
+
+func GetInitCgroup(subsystem string) (string, error) {
+	if IsCgroup2UnifiedMode() {
+		return "", errUnified
+	}
+	cgroups, err := ParseCgroupFile("/proc/1/cgroup")
+	if err != nil {
+		return "", err
+	}
+
+	return getControllerPath(subsystem, cgroups)
+}
+
+func GetInitCgroupPath(subsystem string) (string, error) {
+	cgroup, err := GetInitCgroup(subsystem)
+	if err != nil {
+		return "", err
+	}
+
+	return getCgroupPathHelper(subsystem, cgroup)
+}
+
+func getCgroupPathHelper(subsystem, cgroup string) (string, error) {
+	mnt, root, err := FindCgroupMountpointAndRoot("", subsystem)
+	if err != nil {
+		return "", err
+	}
+
+	// This is needed for nested containers, because in /proc/self/cgroup we
+	// see paths from host, which don't exist in container.
+	relCgroup, err := filepath.Rel(root, cgroup)
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Join(mnt, relCgroup), nil
+}
+
+func getControllerPath(subsystem string, cgroups map[string]string) (string, error) {
+	if IsCgroup2UnifiedMode() {
+		return "", errUnified
+	}
+
+	if p, ok := cgroups[subsystem]; ok {
+		return p, nil
+	}
+
+	if p, ok := cgroups[CgroupNamePrefix+subsystem]; ok {
+		return p, nil
+	}
+
+	return "", NewNotFoundError(subsystem)
+}