Add exec and terminal support

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

cmd/ctr/utils.go

@@ -0,0 +1,122 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"path/filepath"
+	"sync"
+	"syscall"
+	"time"
+
+	gocontext "context"
+
+	"github.com/docker/containerd/api/execution"
+	"github.com/tonistiigi/fifo"
+	"github.com/urfave/cli"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/grpclog"
+)
+
+var grpcConn *grpc.ClientConn
+
+func prepareStdio(in, out, err string) (*sync.WaitGroup, error) {
+	var (
+		wg sync.WaitGroup
+
+		dst   io.Writer
+		src   io.Reader
+		close func()
+	)
+
+	for _, f := range []struct {
+		name   string
+		flags  int
+		src    bool
+		reader io.Reader
+		writer io.Writer
+	}{
+		{in, syscall.O_WRONLY | syscall.O_CREAT | syscall.O_NONBLOCK, false, os.Stdin, nil},
+		{out, syscall.O_RDONLY | syscall.O_CREAT | syscall.O_NONBLOCK, true, nil, os.Stdout},
+		{err, syscall.O_RDONLY | syscall.O_CREAT | syscall.O_NONBLOCK, true, nil, os.Stderr},
+	} {
+		ff, err := fifo.OpenFifo(gocontext.Background(), f.name, f.flags, 0700)
+		if err != nil {
+			return nil, err
+		}
+		defer func(c io.Closer) {
+			if err != nil {
+				c.Close()
+			}
+		}(ff)
+
+		if f.src {
+			src = ff
+			dst = f.writer
+			close = func() {
+				ff.Close()
+				wg.Done()
+			}
+			wg.Add(1)
+		} else {
+			src = f.reader
+			dst = ff
+			close = func() { ff.Close() }
+		}
+
+		go func(dst io.Writer, src io.Reader, close func()) {
+			io.Copy(dst, src)
+			close()
+		}(dst, src, close)
+	}
+
+	return &wg, nil
+}
+
+func getGRPCConnection(context *cli.Context) (*grpc.ClientConn, error) {
+	if grpcConn != nil {
+		return grpcConn, nil
+	}
+
+	bindSocket := context.GlobalString("socket")
+	// reset the logger for grpc to log to dev/null so that it does not mess with our stdio
+	grpclog.SetLogger(log.New(ioutil.Discard, "", log.LstdFlags))
+	dialOpts := []grpc.DialOption{grpc.WithInsecure(), grpc.WithTimeout(100 * time.Second)}
+	dialOpts = append(dialOpts,
+		grpc.WithDialer(func(addr string, timeout time.Duration) (net.Conn, error) {
+			return net.DialTimeout("unix", bindSocket, timeout)
+		},
+		))
+
+	conn, err := grpc.Dial(fmt.Sprintf("unix://%s", bindSocket), dialOpts...)
+	if err != nil {
+		return nil, err
+	}
+
+	grpcConn = conn
+	return grpcConn, nil
+}
+
+func getExecutionService(context *cli.Context) (execution.ExecutionServiceClient, error) {
+	conn, err := getGRPCConnection(context)
+	if err != nil {
+		return nil, err
+	}
+	return execution.NewExecutionServiceClient(conn), nil
+}
+
+func getTempDir(id string) (string, error) {
+	err := os.MkdirAll(filepath.Join(os.TempDir(), "ctr"), 0700)
+	if err != nil {
+		return "", err
+	}
+
+	tmpDir, err := ioutil.TempDir(filepath.Join(os.TempDir(), "ctr"), fmt.Sprintf("%s-", id))
+	if err != nil {
+		return "", err
+	}
+	return tmpDir, nil
+}