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305 lines
8.5 KiB
Go
305 lines
8.5 KiB
Go
// +build linux
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package libcontainer
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import (
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"encoding/json"
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"fmt"
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"os"
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"path/filepath"
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"regexp"
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"runtime/debug"
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"strconv"
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"syscall"
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"github.com/docker/docker/pkg/mount"
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"github.com/opencontainers/runc/libcontainer/cgroups"
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"github.com/opencontainers/runc/libcontainer/cgroups/fs"
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"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
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"github.com/opencontainers/runc/libcontainer/configs"
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"github.com/opencontainers/runc/libcontainer/configs/validate"
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"github.com/opencontainers/runc/libcontainer/utils"
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)
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const (
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stateFilename = "state.json"
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execFifoFilename = "exec.fifo"
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)
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var (
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idRegex = regexp.MustCompile(`^[\w+-\.]+$`)
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maxIdLen = 1024
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)
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// InitArgs returns an options func to configure a LinuxFactory with the
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// provided init binary path and arguments.
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func InitArgs(args ...string) func(*LinuxFactory) error {
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return func(l *LinuxFactory) error {
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l.InitArgs = args
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return nil
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}
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}
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// SystemdCgroups is an options func to configure a LinuxFactory to return
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// containers that use systemd to create and manage cgroups.
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func SystemdCgroups(l *LinuxFactory) error {
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l.NewCgroupsManager = func(config *configs.Cgroup, paths map[string]string) cgroups.Manager {
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return &systemd.Manager{
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Cgroups: config,
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Paths: paths,
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}
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}
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return nil
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}
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// Cgroupfs is an options func to configure a LinuxFactory to return
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// containers that use the native cgroups filesystem implementation to
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// create and manage cgroups.
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func Cgroupfs(l *LinuxFactory) error {
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l.NewCgroupsManager = func(config *configs.Cgroup, paths map[string]string) cgroups.Manager {
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return &fs.Manager{
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Cgroups: config,
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Paths: paths,
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}
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}
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return nil
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}
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// TmpfsRoot is an option func to mount LinuxFactory.Root to tmpfs.
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func TmpfsRoot(l *LinuxFactory) error {
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mounted, err := mount.Mounted(l.Root)
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if err != nil {
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return err
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}
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if !mounted {
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if err := syscall.Mount("tmpfs", l.Root, "tmpfs", 0, ""); err != nil {
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return err
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}
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}
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return nil
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}
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// CriuPath returns an option func to configure a LinuxFactory with the
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// provided criupath
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func CriuPath(criupath string) func(*LinuxFactory) error {
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return func(l *LinuxFactory) error {
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l.CriuPath = criupath
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return nil
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}
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}
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// New returns a linux based container factory based in the root directory and
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// configures the factory with the provided option funcs.
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func New(root string, options ...func(*LinuxFactory) error) (Factory, error) {
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if root != "" {
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if err := os.MkdirAll(root, 0700); err != nil {
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return nil, newGenericError(err, SystemError)
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}
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}
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l := &LinuxFactory{
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Root: root,
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InitArgs: []string{"/proc/self/exe", "init"},
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Validator: validate.New(),
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CriuPath: "criu",
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}
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Cgroupfs(l)
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for _, opt := range options {
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if err := opt(l); err != nil {
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return nil, err
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}
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}
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return l, nil
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}
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// LinuxFactory implements the default factory interface for linux based systems.
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type LinuxFactory struct {
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// Root directory for the factory to store state.
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Root string
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// InitArgs are arguments for calling the init responsibilities for spawning
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// a container.
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InitArgs []string
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// CriuPath is the path to the criu binary used for checkpoint and restore of
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// containers.
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CriuPath string
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// Validator provides validation to container configurations.
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Validator validate.Validator
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// NewCgroupsManager returns an initialized cgroups manager for a single container.
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NewCgroupsManager func(config *configs.Cgroup, paths map[string]string) cgroups.Manager
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}
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func (l *LinuxFactory) Create(id string, config *configs.Config) (Container, error) {
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if l.Root == "" {
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return nil, newGenericError(fmt.Errorf("invalid root"), ConfigInvalid)
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}
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if err := l.validateID(id); err != nil {
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return nil, err
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}
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if err := l.Validator.Validate(config); err != nil {
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return nil, newGenericError(err, ConfigInvalid)
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}
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uid, err := config.HostUID()
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if err != nil {
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return nil, newGenericError(err, SystemError)
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}
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gid, err := config.HostGID()
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if err != nil {
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return nil, newGenericError(err, SystemError)
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}
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containerRoot := filepath.Join(l.Root, id)
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if _, err := os.Stat(containerRoot); err == nil {
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return nil, newGenericError(fmt.Errorf("container with id exists: %v", id), IdInUse)
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} else if !os.IsNotExist(err) {
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return nil, newGenericError(err, SystemError)
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}
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if err := os.MkdirAll(containerRoot, 0711); err != nil {
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return nil, newGenericError(err, SystemError)
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}
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if err := os.Chown(containerRoot, uid, gid); err != nil {
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return nil, newGenericError(err, SystemError)
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}
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fifoName := filepath.Join(containerRoot, execFifoFilename)
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oldMask := syscall.Umask(0000)
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if err := syscall.Mkfifo(fifoName, 0622); err != nil {
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syscall.Umask(oldMask)
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return nil, newGenericError(err, SystemError)
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}
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syscall.Umask(oldMask)
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if err := os.Chown(fifoName, uid, gid); err != nil {
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return nil, newGenericError(err, SystemError)
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}
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c := &linuxContainer{
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id: id,
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root: containerRoot,
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config: config,
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initArgs: l.InitArgs,
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criuPath: l.CriuPath,
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cgroupManager: l.NewCgroupsManager(config.Cgroups, nil),
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}
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c.state = &stoppedState{c: c}
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return c, nil
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}
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func (l *LinuxFactory) Load(id string) (Container, error) {
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if l.Root == "" {
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return nil, newGenericError(fmt.Errorf("invalid root"), ConfigInvalid)
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}
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containerRoot := filepath.Join(l.Root, id)
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state, err := l.loadState(containerRoot, id)
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if err != nil {
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return nil, err
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}
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r := &nonChildProcess{
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processPid: state.InitProcessPid,
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processStartTime: state.InitProcessStartTime,
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fds: state.ExternalDescriptors,
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}
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c := &linuxContainer{
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initProcess: r,
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initProcessStartTime: state.InitProcessStartTime,
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id: id,
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config: &state.Config,
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initArgs: l.InitArgs,
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criuPath: l.CriuPath,
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cgroupManager: l.NewCgroupsManager(state.Config.Cgroups, state.CgroupPaths),
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root: containerRoot,
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created: state.Created,
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}
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c.state = &loadedState{c: c}
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if err := c.refreshState(); err != nil {
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return nil, err
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}
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return c, nil
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}
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func (l *LinuxFactory) Type() string {
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return "libcontainer"
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}
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// StartInitialization loads a container by opening the pipe fd from the parent to read the configuration and state
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// This is a low level implementation detail of the reexec and should not be consumed externally
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func (l *LinuxFactory) StartInitialization() (err error) {
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var pipefd, rootfd int
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for _, pair := range []struct {
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k string
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v *int
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}{
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{"_LIBCONTAINER_INITPIPE", &pipefd},
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{"_LIBCONTAINER_STATEDIR", &rootfd},
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} {
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s := os.Getenv(pair.k)
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i, err := strconv.Atoi(s)
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if err != nil {
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return fmt.Errorf("unable to convert %s=%s to int", pair.k, s)
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}
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*pair.v = i
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}
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var (
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pipe = os.NewFile(uintptr(pipefd), "pipe")
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it = initType(os.Getenv("_LIBCONTAINER_INITTYPE"))
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)
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// clear the current process's environment to clean any libcontainer
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// specific env vars.
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os.Clearenv()
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var i initer
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defer func() {
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// We have an error during the initialization of the container's init,
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// send it back to the parent process in the form of an initError.
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// If container's init successed, syscall.Exec will not return, hence
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// this defer function will never be called.
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if _, ok := i.(*linuxStandardInit); ok {
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// Synchronisation only necessary for standard init.
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if werr := utils.WriteJSON(pipe, syncT{procError}); werr != nil {
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panic(err)
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}
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}
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if werr := utils.WriteJSON(pipe, newSystemError(err)); werr != nil {
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panic(err)
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}
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// ensure that this pipe is always closed
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pipe.Close()
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}()
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defer func() {
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if e := recover(); e != nil {
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err = fmt.Errorf("panic from initialization: %v, %v", e, string(debug.Stack()))
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}
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}()
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i, err = newContainerInit(it, pipe, rootfd)
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if err != nil {
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return err
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}
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return i.Init()
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}
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func (l *LinuxFactory) loadState(root, id string) (*State, error) {
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f, err := os.Open(filepath.Join(root, stateFilename))
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if err != nil {
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if os.IsNotExist(err) {
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return nil, newGenericError(fmt.Errorf("container %q does not exist", id), ContainerNotExists)
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}
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return nil, newGenericError(err, SystemError)
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}
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defer f.Close()
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var state *State
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if err := json.NewDecoder(f).Decode(&state); err != nil {
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return nil, newGenericError(err, SystemError)
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}
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return state, nil
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}
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func (l *LinuxFactory) validateID(id string) error {
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if !idRegex.MatchString(id) {
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return newGenericError(fmt.Errorf("invalid id format: %v", id), InvalidIdFormat)
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}
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if len(id) > maxIdLen {
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return newGenericError(fmt.Errorf("invalid id format: %v", id), InvalidIdFormat)
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}
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return nil
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}
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