diff options
Diffstat (limited to 'vendor/github.com/opencontainers/runc/libcontainer/cgroups/v1_utils.go')
-rw-r--r-- | vendor/github.com/opencontainers/runc/libcontainer/cgroups/v1_utils.go | 250 |
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) +} |