// this expects that we already have our namespaces setup by the C initializer
// we are expected to finalize the namespace and exec the user's application
func nsenter() {
syncPipe, err := syncpipe.NewSyncPipeFromFd(0, 3)
if err != nil {
log.Fatalf("unable to create sync pipe: %s", err)
}
var config *libcontainer.Config
if err := syncPipe.ReadFromParent(&config); err != nil {
log.Fatalf("reading container config from parent: %s", err)
}
if err := namespaces.FinalizeSetns(config, findUserArgs()); err != nil {
log.Fatalf("failed to nsenter: %s", err)
}
}
func nsenterExec() {
runtime.LockOSThread()
// User args are passed after '--' in the command line.
userArgs := findUserArgs()
config, err := loadConfigFromFd()
if err != nil {
log.Fatalf("docker-exec: unable to receive config from sync pipe: %s", err)
}
if err := namespaces.FinalizeSetns(config, userArgs); err != nil {
log.Fatalf("docker-exec: failed to exec: %s", err)
}
}
// init runs the libcontainer initialization code because of the busybox style needs
// to work around the go runtime and the issues with forking
func init() {
if len(os.Args) < 2 {
return
}
// handle init
if len(os.Args) >= 2 && os.Args[1] == "init" {
runtime.LockOSThread()
container, err := loadConfig()
if err != nil {
log.Fatal(err)
}
rootfs, err := os.Getwd()
if err != nil {
log.Fatal(err)
}
if err := namespaces.Init(container, rootfs, "", os.NewFile(3, "pipe"), os.Args[3:]); err != nil {
log.Fatalf("unable to initialize for container: %s", err)
}
os.Exit(1)
}
// handle execin
if len(os.Args) >= 2 && os.Args[0] == "nsenter-exec" {
runtime.LockOSThread()
// User args are passed after '--' in the command line.
userArgs := findUserArgs()
config, err := loadConfigFromFd()
if err != nil {
log.Fatalf("docker-exec: unable to receive config from sync pipe: %s", err)
}
if err := namespaces.FinalizeSetns(config, userArgs); err != nil {
log.Fatalf("docker-exec: failed to exec: %s", err)
}
os.Exit(1)
}
}
// nsenterExec exec's a process inside an existing container
func nsenterExec(config *libcontainer.Config, args []string) {
if err := namespaces.FinalizeSetns(config, args); err != nil {
log.Fatalf("failed to nsenter: %s", err)
}
}