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|
package main
import (
"encoding/json"
"flag"
"io"
"io/ioutil"
"log"
"os"
"path/filepath"
"strconv"
"github.com/dotcloud/docker/pkg/libcontainer"
"github.com/dotcloud/docker/pkg/libcontainer/nsinit"
)
var (
root, console, logs string
pipeFd int
)
func registerFlags() {
flag.StringVar(&console, "console", "", "console (pty slave) path")
flag.IntVar(&pipeFd, "pipe", 0, "sync pipe fd")
flag.StringVar(&root, "root", ".", "root for storing configuration data")
flag.StringVar(&logs, "log", "none", "set stderr or a filepath to enable logging")
flag.Parse()
}
func main() {
registerFlags()
if flag.NArg() < 1 {
log.Fatalf("wrong number of argments %d", flag.NArg())
}
container, err := loadContainer()
if err != nil {
log.Fatalf("Unable to load container: %s", err)
}
l, err := getLogger("[exec] ")
if err != nil {
log.Fatal(err)
}
ns, err := newNsInit(l)
if err != nil {
log.Fatalf("Unable to initialize nsinit: %s", err)
}
switch flag.Arg(0) {
case "exec": // this is executed outside of the namespace in the cwd
var exitCode int
nspid, err := readPid()
if err != nil {
if !os.IsNotExist(err) {
l.Fatalf("Unable to read pid: %s", err)
}
}
if nspid > 0 {
exitCode, err = ns.ExecIn(container, nspid, flag.Args()[1:])
} else {
term := nsinit.NewTerminal(os.Stdin, os.Stdout, os.Stderr, container.Tty)
exitCode, err = ns.Exec(container, term, flag.Args()[1:])
}
if err != nil {
l.Fatalf("Failed to exec: %s", err)
}
os.Exit(exitCode)
case "init": // this is executed inside of the namespace to setup the container
cwd, err := os.Getwd()
if err != nil {
l.Fatal(err)
}
if flag.NArg() < 2 {
l.Fatalf("wrong number of argments %d", flag.NArg())
}
syncPipe, err := nsinit.NewSyncPipeFromFd(0, uintptr(pipeFd))
if err != nil {
l.Fatalf("Unable to create sync pipe: %s", err)
}
if err := ns.Init(container, cwd, console, syncPipe, flag.Args()[1:]); err != nil {
l.Fatalf("Unable to initialize for container: %s", err)
}
default:
l.Fatalf("command not supported for nsinit %s", flag.Arg(0))
}
}
func loadContainer() (*libcontainer.Container, error) {
f, err := os.Open(filepath.Join(root, "container.json"))
if err != nil {
return nil, err
}
defer f.Close()
var container *libcontainer.Container
if err := json.NewDecoder(f).Decode(&container); err != nil {
return nil, err
}
return container, nil
}
func readPid() (int, error) {
data, err := ioutil.ReadFile(filepath.Join(root, "pid"))
if err != nil {
return -1, err
}
pid, err := strconv.Atoi(string(data))
if err != nil {
return -1, err
}
return pid, nil
}
func newNsInit(l *log.Logger) (nsinit.NsInit, error) {
return nsinit.NewNsInit(&nsinit.DefaultCommandFactory{root}, &nsinit.DefaultStateWriter{root}, l), nil
}
func getLogger(prefix string) (*log.Logger, error) {
var w io.Writer
switch logs {
case "", "none":
w = ioutil.Discard
case "stderr":
w = os.Stderr
default: // we have a filepath
f, err := os.OpenFile(logs, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0755)
if err != nil {
return nil, err
}
w = f
}
return log.New(w, prefix, log.LstdFlags), nil
}
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