Move STDIO initialization to libcontainer.Process

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

libcontainer/process.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"math"
 	"os"
+	"syscall"
 )
 
 type processOperations interface {
@@ -78,6 +79,54 @@ func (p Process) Signal(sig os.Signal) error {
 	return p.ops.signal(sig)
 }
 
+// IO holds the process's STDIO
+type IO struct {
+	Stdin  io.WriteCloser
+	Stdout io.ReadCloser
+	Stderr io.ReadCloser
+}
+
+// InitializeIO creates pipes for use with the process's STDIO
+// and returns the opposite side for each
+func (p *Process) InitializeIO(rootuid int) (i *IO, err error) {
+	var fds []uintptr
+	i = &IO{}
+	// cleanup in case of an error
+	defer func() {
+		if err != nil {
+			for _, fd := range fds {
+				syscall.Close(int(fd))
+			}
+		}
+	}()
+	// STDIN
+	r, w, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+	fds = append(fds, r.Fd(), w.Fd())
+	p.Stdin, i.Stdin = r, w
+	// STDOUT
+	if r, w, err = os.Pipe(); err != nil {
+		return nil, err
+	}
+	fds = append(fds, r.Fd(), w.Fd())
+	p.Stdout, i.Stdout = w, r
+	// STDERR
+	if r, w, err = os.Pipe(); err != nil {
+		return nil, err
+	}
+	fds = append(fds, r.Fd(), w.Fd())
+	p.Stderr, i.Stderr = w, r
+	// change ownership of the pipes incase we are in a user namespace
+	for _, fd := range fds {
+		if err := syscall.Fchown(int(fd), rootuid, rootuid); err != nil {
+			return nil, err
+		}
+	}
+	return i, nil
+}
+
 // NewConsole creates new console for process and returns it
 func (p *Process) NewConsole(rootuid int) (Console, error) {
 	console, err := NewConsole(rootuid, rootuid)

restore.go

@@ -126,11 +126,7 @@ func restoreContainer(context *cli.Context, spec *specs.LinuxSpec, config *confi
 			}
 		}
 	}()
-	process := &libcontainer.Process{
+	process := &libcontainer.Process{}
-		Stdin:  os.Stdin,
-		Stdout: os.Stdout,
-		Stderr: os.Stderr,
-	}
 	tty, err := newTty(spec.Process.Terminal, process, rootuid)
 	if err != nil {
 		return -1, err

start.go

@@ -110,12 +110,10 @@ func startContainer(context *cli.Context, spec *specs.LinuxSpec, rspec *specs.Li
 		if err != nil {
 			return -1, err
 		}
-
 		for i := SD_LISTEN_FDS_START; i < (listenFdsInt + SD_LISTEN_FDS_START); i++ {
 			process.ExtraFiles = append(process.ExtraFiles, os.NewFile(uintptr(i), ""))
 		}
 	}
-
 	tty, err := newTty(spec.Process.Terminal, process, rootuid)
 	if err != nil {
 		return -1, err

tty.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"syscall"
 
 	"github.com/docker/docker/pkg/term"
 	"github.com/opencontainers/runc/libcontainer"
@@ -25,38 +24,20 @@ func newTty(create bool, p *libcontainer.Process, rootuid int) (*tty, error) {
 // setup standard pipes so that the TTY of the calling runc process
 // is not inherited by the container.
 func createStdioPipes(p *libcontainer.Process, rootuid int) (*tty, error) {
-	var (
+	i, err := p.InitializeIO(rootuid)
-		t   = &tty{}
-		fds []int
-	)
-	r, w, err := os.Pipe()
 	if err != nil {
 		return nil, err
 	}
-	fds = append(fds, int(r.Fd()), int(w.Fd()))
+	t := &tty{
-	go io.Copy(w, os.Stdin)
+		closers: []io.Closer{
-	t.closers = append(t.closers, w)
+			i.Stdin,
-	p.Stdin = r
+			i.Stdout,
-	if r, w, err = os.Pipe(); err != nil {
+			i.Stderr,
-		return nil, err
+		},
-	}
-	fds = append(fds, int(r.Fd()), int(w.Fd()))
-	go io.Copy(os.Stdout, r)
-	p.Stdout = w
-	t.closers = append(t.closers, r)
-	if r, w, err = os.Pipe(); err != nil {
-		return nil, err
-	}
-	fds = append(fds, int(r.Fd()), int(w.Fd()))
-	go io.Copy(os.Stderr, r)
-	p.Stderr = w
-	t.closers = append(t.closers, r)
-	// change the ownership of the pipe fds incase we are in a user namespace.
-	for _, fd := range fds {
-		if err := syscall.Fchown(fd, rootuid, rootuid); err != nil {
-			return nil, err
-		}
 	}
+	go io.Copy(i.Stdin, os.Stdin)
+	go io.Copy(os.Stdout, i.Stdout)
+	go io.Copy(os.Stderr, i.Stderr)
 	return t, nil
 }
 
@@ -78,9 +59,6 @@ func createTty(p *libcontainer.Process, rootuid int) (*tty, error) {
 			console,
 		},
 	}
-	p.Stderr = nil
-	p.Stdout = nil
-	p.Stdin = nil
 	return t, nil
 }
 

utils.go

@@ -163,8 +163,5 @@ func newProcess(p specs.Process) *libcontainer.Process {
 		// TODO: fix libcontainer's API to better support uid/gid in a typesafe way.
 		User: fmt.Sprintf("%d:%d", p.User.UID, p.User.GID),
 		Cwd:  p.Cwd,
-		Stdin:  os.Stdin,
-		Stdout: os.Stdout,
-		Stderr: os.Stderr,
 	}
 }