/usr/share/gocode/src/github.com/opencontainers/runc/libcontainer/factory_linux.go is in golang-github-opencontainers-runc-dev 1.0.0~rc4+dfsg1-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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package libcontainer
import (
"encoding/json"
"fmt"
"os"
"path/filepath"
"regexp"
"runtime/debug"
"strconv"
"github.com/docker/docker/pkg/mount"
"github.com/opencontainers/runc/libcontainer/cgroups"
"github.com/opencontainers/runc/libcontainer/cgroups/fs"
"github.com/opencontainers/runc/libcontainer/cgroups/rootless"
"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
"github.com/opencontainers/runc/libcontainer/configs"
"github.com/opencontainers/runc/libcontainer/configs/validate"
"github.com/opencontainers/runc/libcontainer/utils"
"golang.org/x/sys/unix"
)
const (
stateFilename = "state.json"
execFifoFilename = "exec.fifo"
)
var idRegex = regexp.MustCompile(`^[\w+-\.]+$`)
// InitArgs returns an options func to configure a LinuxFactory with the
// provided init binary path and arguments.
func InitArgs(args ...string) func(*LinuxFactory) error {
return func(l *LinuxFactory) (err error) {
if len(args) > 0 {
// Resolve relative paths to ensure that its available
// after directory changes.
if args[0], err = filepath.Abs(args[0]); err != nil {
return newGenericError(err, ConfigInvalid)
}
}
l.InitArgs = args
return nil
}
}
// SystemdCgroups is an options func to configure a LinuxFactory to return
// containers that use systemd to create and manage cgroups.
func SystemdCgroups(l *LinuxFactory) error {
l.NewCgroupsManager = func(config *configs.Cgroup, paths map[string]string) cgroups.Manager {
return &systemd.Manager{
Cgroups: config,
Paths: paths,
}
}
return nil
}
// Cgroupfs is an options func to configure a LinuxFactory to return
// containers that use the native cgroups filesystem implementation to
// create and manage cgroups.
func Cgroupfs(l *LinuxFactory) error {
l.NewCgroupsManager = func(config *configs.Cgroup, paths map[string]string) cgroups.Manager {
return &fs.Manager{
Cgroups: config,
Paths: paths,
}
}
return nil
}
// RootlessCgroups is an options func to configure a LinuxFactory to
// return containers that use the "rootless" cgroup manager, which will
// fail to do any operations not possible to do with an unprivileged user.
// It should only be used in conjunction with rootless containers.
func RootlessCgroups(l *LinuxFactory) error {
l.NewCgroupsManager = func(config *configs.Cgroup, paths map[string]string) cgroups.Manager {
return &rootless.Manager{
Cgroups: config,
Paths: paths,
}
}
return nil
}
// TmpfsRoot is an option func to mount LinuxFactory.Root to tmpfs.
func TmpfsRoot(l *LinuxFactory) error {
mounted, err := mount.Mounted(l.Root)
if err != nil {
return err
}
if !mounted {
if err := unix.Mount("tmpfs", l.Root, "tmpfs", 0, ""); err != nil {
return err
}
}
return nil
}
// CriuPath returns an option func to configure a LinuxFactory with the
// provided criupath
func CriuPath(criupath string) func(*LinuxFactory) error {
return func(l *LinuxFactory) error {
l.CriuPath = criupath
return nil
}
}
// New returns a linux based container factory based in the root directory and
// configures the factory with the provided option funcs.
func New(root string, options ...func(*LinuxFactory) error) (Factory, error) {
if root != "" {
if err := os.MkdirAll(root, 0700); err != nil {
return nil, newGenericError(err, SystemError)
}
}
l := &LinuxFactory{
Root: root,
InitArgs: []string{"/proc/self/exe", "init"},
Validator: validate.New(),
CriuPath: "criu",
}
Cgroupfs(l)
for _, opt := range options {
if err := opt(l); err != nil {
return nil, err
}
}
return l, nil
}
// LinuxFactory implements the default factory interface for linux based systems.
type LinuxFactory struct {
// Root directory for the factory to store state.
Root string
// InitArgs are arguments for calling the init responsibilities for spawning
// a container.
InitArgs []string
// CriuPath is the path to the criu binary used for checkpoint and restore of
// containers.
CriuPath string
// Validator provides validation to container configurations.
Validator validate.Validator
// NewCgroupsManager returns an initialized cgroups manager for a single container.
NewCgroupsManager func(config *configs.Cgroup, paths map[string]string) cgroups.Manager
}
func (l *LinuxFactory) Create(id string, config *configs.Config) (Container, error) {
if l.Root == "" {
return nil, newGenericError(fmt.Errorf("invalid root"), ConfigInvalid)
}
if err := l.validateID(id); err != nil {
return nil, err
}
if err := l.Validator.Validate(config); err != nil {
return nil, newGenericError(err, ConfigInvalid)
}
containerRoot := filepath.Join(l.Root, id)
if _, err := os.Stat(containerRoot); err == nil {
return nil, newGenericError(fmt.Errorf("container with id exists: %v", id), IdInUse)
} else if !os.IsNotExist(err) {
return nil, newGenericError(err, SystemError)
}
if err := os.MkdirAll(containerRoot, 0711); err != nil {
return nil, newGenericError(err, SystemError)
}
if err := os.Chown(containerRoot, unix.Geteuid(), unix.Getegid()); err != nil {
return nil, newGenericError(err, SystemError)
}
if config.Rootless {
RootlessCgroups(l)
}
c := &linuxContainer{
id: id,
root: containerRoot,
config: config,
initArgs: l.InitArgs,
criuPath: l.CriuPath,
cgroupManager: l.NewCgroupsManager(config.Cgroups, nil),
}
c.state = &stoppedState{c: c}
return c, nil
}
func (l *LinuxFactory) Load(id string) (Container, error) {
if l.Root == "" {
return nil, newGenericError(fmt.Errorf("invalid root"), ConfigInvalid)
}
containerRoot := filepath.Join(l.Root, id)
state, err := l.loadState(containerRoot, id)
if err != nil {
return nil, err
}
r := &nonChildProcess{
processPid: state.InitProcessPid,
processStartTime: state.InitProcessStartTime,
fds: state.ExternalDescriptors,
}
// We have to use the RootlessManager.
if state.Rootless {
RootlessCgroups(l)
}
c := &linuxContainer{
initProcess: r,
initProcessStartTime: state.InitProcessStartTime,
id: id,
config: &state.Config,
initArgs: l.InitArgs,
criuPath: l.CriuPath,
cgroupManager: l.NewCgroupsManager(state.Config.Cgroups, state.CgroupPaths),
root: containerRoot,
created: state.Created,
}
c.state = &loadedState{c: c}
if err := c.refreshState(); err != nil {
return nil, err
}
return c, nil
}
func (l *LinuxFactory) Type() string {
return "libcontainer"
}
// StartInitialization loads a container by opening the pipe fd from the parent to read the configuration and state
// This is a low level implementation detail of the reexec and should not be consumed externally
func (l *LinuxFactory) StartInitialization() (err error) {
var (
pipefd, rootfd int
consoleSocket *os.File
envInitPipe = os.Getenv("_LIBCONTAINER_INITPIPE")
envStateDir = os.Getenv("_LIBCONTAINER_STATEDIR")
envConsole = os.Getenv("_LIBCONTAINER_CONSOLE")
)
// Get the INITPIPE.
pipefd, err = strconv.Atoi(envInitPipe)
if err != nil {
return fmt.Errorf("unable to convert _LIBCONTAINER_INITPIPE=%s to int: %s", envInitPipe, err)
}
var (
pipe = os.NewFile(uintptr(pipefd), "pipe")
it = initType(os.Getenv("_LIBCONTAINER_INITTYPE"))
)
defer pipe.Close()
// Only init processes have STATEDIR.
rootfd = -1
if it == initStandard {
if rootfd, err = strconv.Atoi(envStateDir); err != nil {
return fmt.Errorf("unable to convert _LIBCONTAINER_STATEDIR=%s to int: %s", envStateDir, err)
}
}
if envConsole != "" {
console, err := strconv.Atoi(envConsole)
if err != nil {
return fmt.Errorf("unable to convert _LIBCONTAINER_CONSOLE=%s to int: %s", envConsole, err)
}
consoleSocket = os.NewFile(uintptr(console), "console-socket")
defer consoleSocket.Close()
}
// clear the current process's environment to clean any libcontainer
// specific env vars.
os.Clearenv()
defer func() {
// We have an error during the initialization of the container's init,
// send it back to the parent process in the form of an initError.
if werr := utils.WriteJSON(pipe, syncT{procError}); werr != nil {
fmt.Fprintln(os.Stderr, err)
return
}
if werr := utils.WriteJSON(pipe, newSystemError(err)); werr != nil {
fmt.Fprintln(os.Stderr, err)
return
}
}()
defer func() {
if e := recover(); e != nil {
err = fmt.Errorf("panic from initialization: %v, %v", e, string(debug.Stack()))
}
}()
i, err := newContainerInit(it, pipe, consoleSocket, rootfd)
if err != nil {
return err
}
// If Init succeeds, syscall.Exec will not return, hence none of the defers will be called.
return i.Init()
}
func (l *LinuxFactory) loadState(root, id string) (*State, error) {
f, err := os.Open(filepath.Join(root, stateFilename))
if err != nil {
if os.IsNotExist(err) {
return nil, newGenericError(fmt.Errorf("container %q does not exist", id), ContainerNotExists)
}
return nil, newGenericError(err, SystemError)
}
defer f.Close()
var state *State
if err := json.NewDecoder(f).Decode(&state); err != nil {
return nil, newGenericError(err, SystemError)
}
return state, nil
}
func (l *LinuxFactory) validateID(id string) error {
if !idRegex.MatchString(id) {
return newGenericError(fmt.Errorf("invalid id format: %v", id), InvalidIdFormat)
}
return nil
}
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