// TODO(vishh): This is part of the libcontainer API and it does much more than just namespaces related work.
// Move this to libcontainer package.
// Exec performs setup outside of a namespace so that a container can be
// executed. Exec is a high level function for working with container namespaces.
func Exec(container *libcontainer.Config, stdin io.Reader, stdout, stderr io.Writer, console string, rootfs, dataPath string, args []string, createCommand CreateCommand, startCallback func()) (int, error) {
var (
err error
)
// create a pipe so that we can syncronize with the namespaced process and
// pass the veth name to the child
syncPipe, err := syncpipe.NewSyncPipe()
if err != nil {
return -1, err
}
defer syncPipe.Close()
command := createCommand(container, console, rootfs, dataPath, os.Args[0], syncPipe.Child(), args)
// Note: these are only used in non-tty mode
// if there is a tty for the container it will be opened within the namespace and the
// fds will be duped to stdin, stdiout, and stderr
command.Stdin = stdin
command.Stdout = stdout
command.Stderr = stderr
if err := command.Start(); err != nil {
return -1, err
}
// Now we passed the pipe to the child, close our side
syncPipe.CloseChild()
started, err := system.GetProcessStartTime(command.Process.Pid)
if err != nil {
return -1, err
}
// Do this before syncing with child so that no children
// can escape the cgroup
cgroupRef, err := SetupCgroups(container, command.Process.Pid)
if err != nil {
command.Process.Kill()
command.Wait()
return -1, err
}
defer cgroupRef.Cleanup()
cgroupPaths, err := cgroupRef.Paths()
if err != nil {
command.Process.Kill()
command.Wait()
return -1, err
}
var networkState network.NetworkState
if err := InitializeNetworking(container, command.Process.Pid, syncPipe, &networkState); err != nil {
command.Process.Kill()
command.Wait()
return -1, err
}
state := &libcontainer.State{
InitPid: command.Process.Pid,
InitStartTime: started,
NetworkState: networkState,
CgroupPaths: cgroupPaths,
}
if err := libcontainer.SaveState(dataPath, state); err != nil {
command.Process.Kill()
command.Wait()
return -1, err
}
defer libcontainer.DeleteState(dataPath)
// Sync with child
if err := syncPipe.ReadFromChild(); err != nil {
command.Process.Kill()
command.Wait()
return -1, err
}
if startCallback != nil {
startCallback()
}
if err := command.Wait(); err != nil {
if _, ok := err.(*exec.ExitError); !ok {
return -1, err
}
}
return command.ProcessState.Sys().(syscall.WaitStatus).ExitStatus(), nil
}
// ExecIn reexec's the initPath with the argv 0 rewrite to "nsenter" so that it is able to run the
// setns code in a single threaded environment joining the existing containers' namespaces.
func ExecIn(container *libcontainer.Config, state *libcontainer.State, userArgs []string, initPath, action string,
stdin io.Reader, stdout, stderr io.Writer, console string, startCallback func(*exec.Cmd)) (int, error) {
args := []string{fmt.Sprintf("nsenter-%s", action), "--nspid", strconv.Itoa(state.InitPid)}
if console != "" {
args = append(args, "--console", console)
}
cmd := &exec.Cmd{
Path: initPath,
Args: append(args, append([]string{"--"}, userArgs...)...),
}
if filepath.Base(initPath) == initPath {
if lp, err := exec.LookPath(initPath); err == nil {
cmd.Path = lp
}
}
pipe, err := syncpipe.NewSyncPipe()
if err != nil {
return -1, err
}
defer pipe.Close()
// Note: these are only used in non-tty mode
// if there is a tty for the container it will be opened within the namespace and the
// fds will be duped to stdin, stdiout, and stderr
cmd.Stdin = stdin
cmd.Stdout = stdout
cmd.Stderr = stderr
cmd.ExtraFiles = []*os.File{pipe.Child()}
if err := cmd.Start(); err != nil {
return -1, err
}
pipe.CloseChild()
// Enter cgroups.
if err := EnterCgroups(state, cmd.Process.Pid); err != nil {
return -1, err
}
if err := pipe.SendToChild(container); err != nil {
cmd.Process.Kill()
cmd.Wait()
return -1, err
}
if startCallback != nil {
startCallback(cmd)
}
if err := cmd.Wait(); err != nil {
if _, ok := err.(*exec.ExitError); !ok {
return -1, err
}
}
return cmd.ProcessState.Sys().(syscall.WaitStatus).ExitStatus(), nil
}