Don't open slave in parent

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)

namespaces/exec.go

@@ -21,10 +21,9 @@ import (
 // Move this to libcontainer package.
 // Exec performs setup outside of a namespace so that a container can be
 // executed.  Exec is a high level function for working with container namespaces.
-func Exec(container *libcontainer.Config, stdin io.Reader, stdout, stderr io.Writer, rootfs, dataPath string, args []string, createCommand CreateCommand, startCallback func()) (int, error) {
+func Exec(container *libcontainer.Config, stdin io.Reader, stdout, stderr io.Writer, console string, rootfs, dataPath string, args []string, createCommand CreateCommand, startCallback func()) (int, error) {
 	var (
-		console string
-		err     error
+		err error
 	)
 
 	// create a pipe so that we can syncronize with the namespaced process and
@@ -35,12 +34,10 @@ func Exec(container *libcontainer.Config, stdin io.Reader, stdout, stderr io.Wri
 	}
 	defer syncPipe.Close()
 
-	if f, ok := stdin.(*os.File); ok {
-		console = f.Name()
-	}
-
 	command := createCommand(container, console, rootfs, dataPath, os.Args[0], syncPipe.Child(), args)
-
+	// Note: these are only used in non-tty mode
+	// if there is a tty for the container it will be opened within the namespace and the
+	// fds will be duped to stdin, stdiout, and stderr
 	command.Stdin = stdin
 	command.Stdout = stdout
 	command.Stderr = stderr

nsinit/exec.go

@@ -69,27 +69,25 @@ func startContainer(container *libcontainer.Config, dataPath string, args []stri
 	}
 
 	var (
-		master    *os.File
-		slavePath string
-		err       error
-		stdin     = os.Stdin
-		stdout    = os.Stdout
-		stderr    = os.Stderr
+		master  *os.File
+		console string
+		err     error
+
+		stdin  = os.Stdin
+		stdout = os.Stdout
+		stderr = os.Stderr
 	)
 
 	if container.Tty {
-		master, slavePath, err = consolepkg.CreateMasterAndConsole()
+		stdin = nil
+		stdout = nil
+		stderr = nil
+
+		master, console, err = consolepkg.CreateMasterAndConsole()
 		if err != nil {
 			return -1, err
 		}
 
-		slave, err := consolepkg.OpenTerminal(slavePath, syscall.O_RDWR|syscall.O_NOCTTY)
-		if err != nil {
-			return -1, err
-		}
-
-		stdin, stdout, stderr = slave, slave, slave
-
 		go io.Copy(master, os.Stdin)
 		go io.Copy(os.Stdout, master)
 
@@ -116,7 +114,7 @@ func startContainer(container *libcontainer.Config, dataPath string, args []stri
 		}()
 	}
 
-	return namespaces.Exec(container, stdin, stdout, stderr, "", dataPath, args, createCommand, startCallback)
+	return namespaces.Exec(container, stdin, stdout, stderr, console, "", dataPath, args, createCommand, startCallback)
 }
 
 func resizeTty(master *os.File) {