Portability fixes for containerd shim

Update go-runc to master with portability fixes.

Subreaper only exists on Linux, and only Linux runs the shim in a
mount namespace.

With these changes the shim compiles on Darwin, which means the
whole build compiles without errors now.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

vendor/github.com/containerd/go-runc/command_linux.go

@@ -0,0 +1,21 @@
+package runc
+
+import (
+	"context"
+	"os/exec"
+	"syscall"
+)
+
+func (r *Runc) command(context context.Context, args ...string) *exec.Cmd {
+	command := r.Command
+	if command == "" {
+		command = DefaultCommand
+	}
+	cmd := exec.CommandContext(context, command, append(r.args(), args...)...)
+	if r.PdeathSignal != 0 {
+		cmd.SysProcAttr = &syscall.SysProcAttr{
+			Pdeathsig: r.PdeathSignal,
+		}
+	}
+	return cmd
+}

vendor/github.com/containerd/go-runc/command_other.go

@@ -0,0 +1,16 @@
+// +build !linux
+
+package runc
+
+import (
+	"context"
+	"os/exec"
+)
+
+func (r *Runc) command(context context.Context, args ...string) *exec.Cmd {
+	command := r.Command
+	if command == "" {
+		command = DefaultCommand
+	}
+	return exec.CommandContext(context, command, append(r.args(), args...)...)
+}

vendor/github.com/containerd/go-runc/console.go

@@ -10,7 +10,7 @@ import (
 	"path/filepath"
 
 	"github.com/containerd/console"
-	"github.com/opencontainers/runc/libcontainer/utils"
+	"golang.org/x/sys/unix"
 )
 
 // NewConsoleSocket creates a new unix socket at the provided path to accept a
@@ -20,13 +20,16 @@ func NewConsoleSocket(path string) (*Socket, error) {
 	if err != nil {
 		return nil, err
 	}
-	l, err := net.Listen("unix", abs)
+	addr, err := net.ResolveUnixAddr("unix", abs)
+	if err != nil {
+		return nil, err
+	}
+	l, err := net.ListenUnix("unix", addr)
 	if err != nil {
 		return nil, err
 	}
 	return &Socket{
 		l:    l,
-		path: abs,
 	}, nil
 }
 
@@ -41,27 +44,73 @@ func NewTempConsoleSocket() (*Socket, error) {
 	if err != nil {
 		return nil, err
 	}
-	l, err := net.Listen("unix", abs)
+	addr, err := net.ResolveUnixAddr("unix", abs)
+	if err != nil {
+		return nil, err
+	}
+	l, err := net.ListenUnix("unix", addr)
 	if err != nil {
 		return nil, err
 	}
 	return &Socket{
 		l:     l,
 		rmdir: true,
-		path:  abs,
 	}, nil
 }
 
 // Socket is a unix socket that accepts the pty master created by runc
 type Socket struct {
-	path  string
 	rmdir bool
-	l     net.Listener
+	l     *net.UnixListener
 }
 
 // Path returns the path to the unix socket on disk
 func (c *Socket) Path() string {
-	return c.path
+	return c.l.Addr().String()
+}
+
+// recvFd waits for a file descriptor to be sent over the given AF_UNIX
+// socket. The file name of the remote file descriptor will be recreated
+// locally (it is sent as non-auxiliary data in the same payload).
+func recvFd(socket *net.UnixConn) (*os.File, error) {
+	const MaxNameLen = 4096
+	var oobSpace = unix.CmsgSpace(4)
+
+	name := make([]byte, MaxNameLen)
+	oob := make([]byte, oobSpace)
+
+	n, oobn, _, _, err := socket.ReadMsgUnix(name, oob)
+	if err != nil {
+		return nil, err
+	}
+
+	if n >= MaxNameLen || oobn != oobSpace {
+		return nil, fmt.Errorf("recvfd: incorrect number of bytes read (n=%d oobn=%d)", n, oobn)
+	}
+
+	// Truncate.
+	name = name[:n]
+	oob = oob[:oobn]
+
+	scms, err := unix.ParseSocketControlMessage(oob)
+	if err != nil {
+		return nil, err
+	}
+	if len(scms) != 1 {
+		return nil, fmt.Errorf("recvfd: number of SCMs is not 1: %d", len(scms))
+	}
+	scm := scms[0]
+
+	fds, err := unix.ParseUnixRights(&scm)
+	if err != nil {
+		return nil, err
+	}
+	if len(fds) != 1 {
+		return nil, fmt.Errorf("recvfd: number of fds is not 1: %d", len(fds))
+	}
+	fd := uintptr(fds[0])
+
+	return os.NewFile(fd, string(name)), nil
 }
 
 // ReceiveMaster blocks until the socket receives the pty master
@@ -71,15 +120,11 @@ func (c *Socket) ReceiveMaster() (console.Console, error) {
 		return nil, err
 	}
 	defer conn.Close()
-	unix, ok := conn.(*net.UnixConn)
+	uc, ok := conn.(*net.UnixConn)
 	if !ok {
 		return nil, fmt.Errorf("received connection which was not a unix socket")
 	}
-	sock, err := unix.File()
-	if err != nil {
-		return nil, err
-	}
-	f, err := utils.RecvFd(sock)
+	f, err := recvFd(uc)
 	if err != nil {
 		return nil, err
 	}
@@ -90,7 +135,7 @@ func (c *Socket) ReceiveMaster() (console.Console, error) {
 func (c *Socket) Close() error {
 	err := c.l.Close()
 	if c.rmdir {
-		if rerr := os.RemoveAll(filepath.Dir(c.path)); err == nil {
+		if rerr := os.RemoveAll(filepath.Dir(c.Path())); err == nil {
 			err = rerr
 		}
 	}

vendor/github.com/containerd/go-runc/runc.go

@@ -523,20 +523,6 @@ func (r *Runc) args() (out []string) {
 	return out
 }
 
-func (r *Runc) command(context context.Context, args ...string) *exec.Cmd {
-	command := r.Command
-	if command == "" {
-		command = DefaultCommand
-	}
-	cmd := exec.CommandContext(context, command, append(r.args(), args...)...)
-	if r.PdeathSignal != 0 {
-		cmd.SysProcAttr = &syscall.SysProcAttr{
-			Pdeathsig: r.PdeathSignal,
-		}
-	}
-	return cmd
-}
-
 // runOrError will run the provided command.  If an error is
 // encountered and neither Stdout or Stderr was set the error and the
 // stderr of the command will be returned in the format of <error>: