Add shim for reattach of processes

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

Remove runtime files from containerd

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

Update supervisor for orphaned containers

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

Remove ctr/container.go back to rpc calls

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

Add attach to loaded container

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

Add monitor based on epoll for process exits

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

Convert pids in containerd to string

This is so that we no longer care about linux or system level pids and
processes in containerd have user defined process id(pid) kinda like the
exec process ids that docker has today.

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

Add reaper back to containerd

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

Implement list containers with new process model

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

Implement restore of processes

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

Add NONBLOCK to exit fifo open

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

Implement tty reattach

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

Fix race in exit pipe creation

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

Add delete to shim

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

Update shim to use pid-file and not stdout

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

runtime/process.go

@@ -0,0 +1,141 @@
+package runtime
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"syscall"
+
+	"github.com/opencontainers/specs"
+)
+
+func newProcess(root, id string, c *container, s specs.Process) (*process, error) {
+	p := &process{
+		root:      root,
+		id:        id,
+		container: c,
+		spec:      s,
+	}
+	// create fifo's for the process
+	for name, fd := range map[string]*string{
+		"stdin":  &p.stdin,
+		"stdout": &p.stdout,
+		"stderr": &p.stderr,
+	} {
+		path := filepath.Join(root, name)
+		if err := syscall.Mkfifo(path, 0755); err != nil && !os.IsExist(err) {
+			return nil, err
+		}
+		*fd = path
+	}
+	exit, err := getExitPipe(filepath.Join(root, ExitFile))
+	if err != nil {
+		return nil, err
+	}
+	p.exitPipe = exit
+	return p, nil
+}
+
+func loadProcess(root, id string, c *container, s specs.Process) (*process, error) {
+	p := &process{
+		root:      root,
+		id:        id,
+		container: c,
+		spec:      s,
+		stdin:     filepath.Join(root, "stdin"),
+		stdout:    filepath.Join(root, "stdout"),
+		stderr:    filepath.Join(root, "stderr"),
+	}
+	if _, err := p.ExitStatus(); err != nil {
+		if err == ErrProcessNotExited {
+			exit, err := getExitPipe(filepath.Join(root, ExitFile))
+			if err != nil {
+				return nil, err
+			}
+			p.exitPipe = exit
+			return p, nil
+		}
+		return nil, err
+	}
+	return nil, ErrProcessExited
+}
+
+func getExitPipe(path string) (*os.File, error) {
+	if err := syscall.Mkfifo(path, 0755); err != nil && !os.IsExist(err) {
+		return nil, err
+	}
+	// add NONBLOCK in case the other side has already closed or else
+	// this function would never return
+	return os.OpenFile(path, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
+}
+
+type process struct {
+	root string
+	id   string
+	// stdio fifos
+	stdin  string
+	stdout string
+	stderr string
+
+	exitPipe  *os.File
+	container *container
+	spec      specs.Process
+}
+
+func (p *process) ID() string {
+	return p.id
+}
+
+func (p *process) Container() Container {
+	return p.container
+}
+
+// ExitFD returns the fd of the exit pipe
+func (p *process) ExitFD() int {
+	return int(p.exitPipe.Fd())
+}
+
+func (p *process) ExitStatus() (int, error) {
+	data, err := ioutil.ReadFile(filepath.Join(p.root, ExitStatusFile))
+	if err != nil {
+		if os.IsNotExist(err) {
+			return -1, ErrProcessNotExited
+		}
+		return -1, err
+	}
+	if len(data) == 0 {
+		return -1, ErrProcessNotExited
+	}
+	i, err := strconv.Atoi(string(data))
+	if err != nil {
+		return -1, err
+	}
+	return i, nil
+}
+
+// Signal sends the provided signal to the process
+func (p *process) Signal(s os.Signal) error {
+	return errNotImplemented
+}
+
+func (p *process) Spec() specs.Process {
+	return p.spec
+}
+
+func (p *process) Stdin() string {
+	return p.stdin
+}
+
+func (p *process) Stdout() string {
+	return p.stdout
+}
+
+func (p *process) Stderr() string {
+	return p.stderr
+}
+
+// Close closes any open files and/or resouces on the process
+func (p *process) Close() error {
+	return p.exitPipe.Close()
+}