utils.go

// +build linux

package main

import (
	"fmt"
	"os"
	"path/filepath"

	"github.com/codegangsta/cli"
	"github.com/opencontainers/runc/libcontainer"
	"github.com/opencontainers/runc/libcontainer/configs"
	"github.com/opencontainers/specs"
)

const wildcard = -1

var allowedDevices = []*configs.Device{
	// allow mknod for any device
	{
		Type:        'c',
		Major:       wildcard,
		Minor:       wildcard,
		Permissions: "m",
	},
	{
		Type:        'b',
		Major:       wildcard,
		Minor:       wildcard,
		Permissions: "m",
	},
	{
		Path:        "/dev/console",
		Type:        'c',
		Major:       5,
		Minor:       1,
		Permissions: "rwm",
	},
	{
		Path:        "/dev/tty0",
		Type:        'c',
		Major:       4,
		Minor:       0,
		Permissions: "rwm",
	},
	{
		Path:        "/dev/tty1",
		Type:        'c',
		Major:       4,
		Minor:       1,
		Permissions: "rwm",
	},
	// /dev/pts/ - pts namespaces are "coming soon"
	{
		Path:        "",
		Type:        'c',
		Major:       136,
		Minor:       wildcard,
		Permissions: "rwm",
	},
	{
		Path:        "",
		Type:        'c',
		Major:       5,
		Minor:       2,
		Permissions: "rwm",
	},
	// tuntap
	{
		Path:        "",
		Type:        'c',
		Major:       10,
		Minor:       200,
		Permissions: "rwm",
	},
}

var container libcontainer.Container

func containerPreload(context *cli.Context) error {
	c, err := getContainer(context)
	if err != nil {
		return err
	}
	container = c
	return nil
}

var factory libcontainer.Factory

func factoryPreload(context *cli.Context) error {
	f, err := loadFactory(context)
	if err != nil {
		return err
	}
	factory = f
	return nil
}

// loadFactory returns the configured factory instance for execing containers.
func loadFactory(context *cli.Context) (libcontainer.Factory, error) {
	root := context.GlobalString("root")
	abs, err := filepath.Abs(root)
	if err != nil {
		return nil, err
	}
	return libcontainer.New(abs, libcontainer.Cgroupfs, func(l *libcontainer.LinuxFactory) error {
		l.CriuPath = context.GlobalString("criu")
		return nil
	})
}

// getContainer returns the specified container instance by loading it from state
// with the default factory.
func getContainer(context *cli.Context) (libcontainer.Container, error) {
	factory, err := loadFactory(context)
	if err != nil {
		return nil, err
	}
	container, err := factory.Load(context.GlobalString("id"))
	if err != nil {
		return nil, err
	}
	return container, nil
}

// fatal prints the error's details if it is a libcontainer specific error type
// then exits the program with an exit status of 1.
func fatal(err error) {
	if lerr, ok := err.(libcontainer.Error); ok {
		lerr.Detail(os.Stderr)
		os.Exit(1)
	}
	fmt.Fprintln(os.Stderr, err)
	os.Exit(1)
}

// fatalf formats the errror string with the specified template then exits the
// program with an exit status of 1.
func fatalf(t string, v ...interface{}) {
	fmt.Fprintf(os.Stderr, t, v...)
	os.Exit(1)
}

// getDefaultID returns a string to be used as the container id based on the
// current working directory of the runc process.  This function panics
// if the cwd is unable to be found based on a system error.
func getDefaultID() string {
	cwd, err := os.Getwd()
	if err != nil {
		panic(err)
	}
	return filepath.Base(cwd)
}

func getDefaultImagePath(context *cli.Context) string {
	cwd, err := os.Getwd()
	if err != nil {
		panic(err)
	}
	return filepath.Join(cwd, "checkpoint")
}

// newProcess returns a new libcontainer Process with the arguments from the
// spec and stdio from the current process.
func newProcess(p specs.Process) *libcontainer.Process {
	return &libcontainer.Process{
		Args: p.Args,
		Env:  p.Env,
		// TODO: fix libcontainer's API to better support uid/gid in a typesafe way.
		User:   fmt.Sprintf("%d:%d", p.User.UID, p.User.GID),
		Cwd:    p.Cwd,
		Stdin:  os.Stdin,
		Stdout: os.Stdout,
		Stderr: os.Stderr,
	}
}