Update shim for exec

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

containerd-shim/process.go

@@ -0,0 +1,165 @@
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"syscall"
+
+	"github.com/opencontainers/runc/libcontainer"
+	"github.com/opencontainers/specs"
+)
+
+type process struct {
+	id           string
+	bundle       string
+	stdio        *stdio
+	s            specs.Process
+	exec         bool
+	containerPid int
+}
+
+func newProcess(id, bundle string, exec bool) (*process, error) {
+	f, err := os.Open("process.json")
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	p := &process{
+		id:     id,
+		bundle: bundle,
+		exec:   exec,
+	}
+	if err := json.NewDecoder(f).Decode(&p.s); err != nil {
+		return nil, err
+	}
+	if err := p.openIO(); err != nil {
+		return nil, err
+	}
+	return p, nil
+}
+
+func (p *process) start() error {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return err
+	}
+	args := []string{
+		"--id", p.id,
+	}
+	if p.exec {
+		args = append(args, "exec",
+			"--process", filepath.Join(cwd, "process.json"))
+	} else {
+		args = append(args, "start",
+			"--bundle", p.bundle)
+	}
+	args = append(args,
+		"-d",
+		"--console", p.stdio.console,
+		"--pid-file", filepath.Join(cwd, "pid"),
+	)
+	cmd := exec.Command("runc", args...)
+	cmd.Stdin = p.stdio.stdin
+	cmd.Stdout = p.stdio.stdout
+	cmd.Stderr = p.stdio.stderr
+	// set the parent death signal to SIGKILL so that if the shim dies the container
+	// process also dies
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Pdeathsig: syscall.SIGKILL,
+	}
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+	data, err := ioutil.ReadFile("pid")
+	if err != nil {
+		return err
+	}
+	pid, err := strconv.Atoi(string(data))
+	if err != nil {
+		return err
+	}
+	p.containerPid = pid
+	return nil
+
+}
+
+func (p *process) pid() int {
+	return p.containerPid
+}
+
+func (p *process) delete() error {
+	if !p.exec {
+		return exec.Command("runc", "--id", p.id, "delete").Run()
+	}
+	return nil
+}
+
+// openIO opens the pre-created fifo's for use with the container
+// in RDWR so that they remain open if the other side stops listening
+func (p *process) openIO() error {
+	p.stdio = &stdio{}
+	if p.s.Terminal {
+		// FIXME: this is wrong for user namespaces and will need to be translated
+		console, err := libcontainer.NewConsole(int(p.s.User.UID), int(p.s.User.GID))
+		if err != nil {
+			return err
+		}
+		p.stdio.console = console.Path()
+		stdin, err := os.OpenFile("stdin", syscall.O_RDWR, 0)
+		if err != nil {
+			return err
+		}
+		go func() {
+			io.Copy(console, stdin)
+		}()
+		stdout, err := os.OpenFile("stdout", syscall.O_RDWR, 0)
+		if err != nil {
+			return err
+		}
+		go func() {
+			io.Copy(stdout, console)
+			console.Close()
+		}()
+		return nil
+	}
+	// non-tty
+	for name, dest := range map[string]**os.File{
+		"stdin":  &p.stdio.stdin,
+		"stdout": &p.stdio.stdout,
+		"stderr": &p.stdio.stderr,
+	} {
+		f, err := os.OpenFile(name, syscall.O_RDWR, 0)
+		if err != nil {
+			return err
+		}
+		*dest = f
+	}
+	return nil
+}
+
+func (p *process) Close() error {
+	return p.stdio.Close()
+}
+
+type stdio struct {
+	stdin   *os.File
+	stdout  *os.File
+	stderr  *os.File
+	console string
+}
+
+func (s *stdio) Close() error {
+	err := s.stdin.Close()
+	if oerr := s.stdout.Close(); err == nil {
+		err = oerr
+	}
+	if oerr := s.stderr.Close(); err == nil {
+		err = oerr
+	}
+	return err
+}