From a9644c209f7764f9155db0c4aeb4f690c0cdb585 Mon Sep 17 00:00:00 2001
From: Alexander Morozov <lk4d4@docker.com>
Date: Wed, 4 Mar 2015 16:04:20 -0800
Subject: [PATCH] Add tty support for setnsProcess

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
---
 container_linux.go         |  5 +++
 integration/execin_test.go | 72 ++++++++++++++++++++++++++++++++++++++
 nsenter/nsexec.c           | 39 +++++++++++++++++++--
 3 files changed, 113 insertions(+), 3 deletions(-)

diff --git a/container_linux.go b/container_linux.go
index 64258792..bf729760 100644
--- a/container_linux.go
+++ b/container_linux.go
@@ -175,6 +175,11 @@ func (c *linuxContainer) newSetnsProcess(p *Process, cmd *exec.Cmd, parentPipe,
 		fmt.Sprintf("_LIBCONTAINER_INITPID=%d", c.initProcess.pid()),
 		"_LIBCONTAINER_INITTYPE=setns",
 	)
+
+	if p.consolePath != "" {
+		cmd.Env = append(cmd.Env, "_LIBCONTAINER_CONSOLE_PATH="+p.consolePath)
+	}
+
 	// TODO: set on container for process management
 	return &setnsProcess{
 		cmd:         cmd,
diff --git a/integration/execin_test.go b/integration/execin_test.go
index 92a1ae0f..524ee454 100644
--- a/integration/execin_test.go
+++ b/integration/execin_test.go
@@ -1,9 +1,12 @@
 package integration
 
 import (
+	"bytes"
+	"io"
 	"os"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/docker/libcontainer"
 )
@@ -173,3 +176,72 @@ func TestExecInError(t *testing.T) {
 		t.Fatalf("Should be error about not found executable, got %s", err)
 	}
 }
+
+func TestExecInTTY(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+	rootfs, err := newRootfs()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer remove(rootfs)
+	config := newTemplateConfig(rootfs)
+	container, err := newContainer(config)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer container.Destroy()
+
+	// Execute a first process in the container
+	stdinR, stdinW, err := os.Pipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	process := &libcontainer.Process{
+		Args:  []string{"cat"},
+		Env:   standardEnvironment,
+		Stdin: stdinR,
+	}
+	err = container.Start(process)
+	stdinR.Close()
+	defer stdinW.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var stdout bytes.Buffer
+	ps := &libcontainer.Process{
+		Args: []string{"ps"},
+		Env:  standardEnvironment,
+	}
+	console, err := ps.NewConsole(0)
+	copy := make(chan struct{})
+	go func() {
+		io.Copy(&stdout, console)
+		close(copy)
+	}()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = container.Start(ps)
+	if err != nil {
+		t.Fatal(err)
+	}
+	select {
+	case <-time.After(5 * time.Second):
+		t.Fatal("Waiting for copy timed out")
+	case <-copy:
+	}
+	if _, err := ps.Wait(); err != nil {
+		t.Fatal(err)
+	}
+	stdinW.Close()
+	if _, err := process.Wait(); err != nil {
+		t.Log(err)
+	}
+	out := stdout.String()
+	if !strings.Contains(out, "cat") || !strings.Contains(string(out), "ps") {
+		t.Fatalf("unexpected running process, output %q", out)
+	}
+}
diff --git a/nsenter/nsexec.c b/nsenter/nsexec.c
index 5b62729a..e7658f38 100644
--- a/nsenter/nsexec.c
+++ b/nsenter/nsexec.c
@@ -10,6 +10,7 @@
 #include <sys/wait.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/ioctl.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <setjmp.h>
@@ -27,14 +28,14 @@ struct clone_arg {
 	jmp_buf *env;
 };
 
+#define pr_perror(fmt, ...) fprintf(stderr, "nsenter: " fmt ": %m\n", ##__VA_ARGS__)
+
 static int child_func(void *_arg)
 {
 	struct clone_arg *arg = (struct clone_arg *)_arg;
 	longjmp(*arg->env, 1);
 }
 
-#define pr_perror(fmt, ...) fprintf(stderr, "nsenter: " fmt ": %m\n", ##__VA_ARGS__)
-
 // Use raw setns syscall for versions of glibc that don't include it (namely glibc-2.12)
 #if __GLIBC__ == 2 && __GLIBC_MINOR__ < 14
 #define _GNU_SOURCE
@@ -65,8 +66,9 @@ void nsexec()
 	const int num = sizeof(namespaces) / sizeof(char *);
 	jmp_buf env;
 	char buf[PATH_MAX], *val;
-	int i, tfd, child, len;
+	int i, tfd, child, len, consolefd = -1;
 	pid_t pid;
+	char *console;
 
 	val = getenv("_LIBCONTAINER_INITPID");
 	if (val == NULL)
@@ -79,6 +81,15 @@ void nsexec()
 		exit(1);
 	}
 
+	console = getenv("_LIBCONTAINER_CONSOLE_PATH");
+	if (console != NULL) {
+		consolefd = open(console, O_RDWR);
+		if (consolefd < 0) {
+			pr_perror("Failed to open console %s", console);
+			exit(1);
+		}
+	}
+
 	/* Check that the specified process exists */
 	snprintf(buf, PATH_MAX - 1, "/proc/%d/ns", pid);
 	tfd = open(buf, O_DIRECTORY | O_RDONLY);
@@ -113,6 +124,28 @@ void nsexec()
 	}
 
 	if (setjmp(env) == 1) {
+		if (setsid() == -1) {
+			pr_perror("setsid failed");
+			exit(1);
+		}
+		if (consolefd != -1) {
+			if (ioctl(consolefd, TIOCSCTTY, 0) == -1) {
+				pr_perror("ioctl TIOCSCTTY failed");
+				exit(1);
+			}
+			if (dup2(consolefd, STDIN_FILENO) != STDIN_FILENO) {
+				pr_perror("Failed to dup 0");
+				exit(1);
+			}
+			if (dup2(consolefd, STDOUT_FILENO) != STDOUT_FILENO) {
+				pr_perror("Failed to dup 1");
+				exit(1);
+			}
+			if (dup2(consolefd, STDERR_FILENO) != STDERR_FILENO) {
+				pr_perror("Failed to dup 2");
+				exit(1);
+			}
+		}
 		// Finish executing, let the Go runtime take over.
 		return;
 	}