Update go-runc to 7b66c5da30493c5eb9c655cab67ba88071891ac5

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

vendor/github.com/crosbymichael/go-runc/io.go

@@ -0,0 +1,121 @@
+package runc
+
+import (
+	"io"
+	"os"
+	"os/exec"
+	"syscall"
+)
+
+type IO interface {
+	io.Closer
+	Stdin() io.WriteCloser
+	Stdout() io.ReadCloser
+	Stderr() io.ReadCloser
+	Set(*exec.Cmd)
+}
+
+// NewPipeIO creates pipe pairs to be used with runc
+func NewPipeIO(uid, gid int) (i IO, err error) {
+	var pipes []*pipe
+	// cleanup in case of an error
+	defer func() {
+		if err != nil {
+			for _, p := range pipes {
+				p.Close()
+			}
+		}
+	}()
+	stdin, err := newPipe(uid, gid)
+	if err != nil {
+		return nil, err
+	}
+	pipes = append(pipes, stdin)
+
+	stdout, err := newPipe(uid, gid)
+	if err != nil {
+		return nil, err
+	}
+	pipes = append(pipes, stdout)
+
+	stderr, err := newPipe(uid, gid)
+	if err != nil {
+		return nil, err
+	}
+	pipes = append(pipes, stderr)
+
+	return &pipeIO{
+		in:  stdin,
+		out: stdout,
+		err: stderr,
+	}, nil
+}
+
+func newPipe(uid, gid int) (*pipe, error) {
+	r, w, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+	if err := syscall.Fchown(int(r.Fd()), uid, gid); err != nil {
+		return nil, err
+	}
+	if err := syscall.Fchown(int(w.Fd()), uid, gid); err != nil {
+		return nil, err
+	}
+	return &pipe{
+		r: r,
+		w: w,
+	}, nil
+}
+
+type pipe struct {
+	r *os.File
+	w *os.File
+}
+
+func (p *pipe) Close() error {
+	err := p.r.Close()
+	if werr := p.w.Close(); err == nil {
+		err = werr
+	}
+	return err
+}
+
+type pipeIO struct {
+	in  *pipe
+	out *pipe
+	err *pipe
+}
+
+func (i *pipeIO) Stdin() io.WriteCloser {
+	return i.in.w
+}
+
+func (i *pipeIO) Stdout() io.ReadCloser {
+	return i.in.r
+}
+
+func (i *pipeIO) Stderr() io.ReadCloser {
+	return i.in.r
+}
+
+func (i *pipeIO) Close() error {
+	var err error
+	for _, v := range []*pipe{
+		i.in,
+		i.out,
+		i.err,
+	} {
+		if cerr := v.Close(); err == nil {
+			err = cerr
+		}
+	}
+	return err
+}
+
+// Set sets the io to the exec.Cmd
+func (i *pipeIO) Set(cmd *exec.Cmd) {
+	cmd.Stdin = i.in.r
+	cmd.Stdout = i.out.w
+	cmd.Stderr = i.err.w
+}