Add initial system pkg to libcontainer

Port over console and ptmx code into console package
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)

console/console.go

@@ -7,22 +7,24 @@ import (
 	"os"
 	"path/filepath"
 	"syscall"
+	"unsafe"
 
 	"github.com/docker/libcontainer/label"
-	"github.com/dotcloud/docker/pkg/system"
 )
 
 // Setup initializes the proper /dev/console inside the rootfs path
 func Setup(rootfs, consolePath, mountLabel string) error {
-	oldMask := system.Umask(0000)
-	defer system.Umask(oldMask)
+	oldMask := syscall.Umask(0000)
+	defer syscall.Umask(oldMask)
 
 	if err := os.Chmod(consolePath, 0600); err != nil {
 		return err
 	}
+
 	if err := os.Chown(consolePath, 0, 0); err != nil {
 		return err
 	}
+
 	if err := label.SetFileLabel(consolePath, mountLabel); err != nil {
 		return fmt.Errorf("set file label %s %s", consolePath, err)
 	}
@@ -33,26 +35,91 @@ func Setup(rootfs, consolePath, mountLabel string) error {
 	if err != nil && !os.IsExist(err) {
 		return fmt.Errorf("create %s %s", dest, err)
 	}
+
 	if f != nil {
 		f.Close()
 	}
 
-	if err := system.Mount(consolePath, dest, "bind", syscall.MS_BIND, ""); err != nil {
+	if err := syscall.Mount(consolePath, dest, "bind", syscall.MS_BIND, ""); err != nil {
 		return fmt.Errorf("bind %s to %s %s", consolePath, dest, err)
 	}
+
 	return nil
 }
 
 func OpenAndDup(consolePath string) error {
-	slave, err := system.OpenTerminal(consolePath, syscall.O_RDWR)
+	slave, err := OpenTerminal(consolePath, syscall.O_RDWR)
 	if err != nil {
 		return fmt.Errorf("open terminal %s", err)
 	}
-	if err := system.Dup2(slave.Fd(), 0); err != nil {
+
+	if err := syscall.Dup2(int(slave.Fd()), 0); err != nil {
 		return err
 	}
-	if err := system.Dup2(slave.Fd(), 1); err != nil {
+
+	if err := syscall.Dup2(int(slave.Fd()), 1); err != nil {
 		return err
 	}
-	return system.Dup2(slave.Fd(), 2)
+
+	return syscall.Dup2(int(slave.Fd()), 2)
+}
+
+// Unlockpt unlocks the slave pseudoterminal device corresponding to the master pseudoterminal referred to by f.
+// Unlockpt should be called before opening the slave side of a pseudoterminal.
+func Unlockpt(f *os.File) error {
+	var u int
+
+	return Ioctl(f.Fd(), syscall.TIOCSPTLCK, uintptr(unsafe.Pointer(&u)))
+}
+
+// Ptsname retrieves the name of the first available pts for the given master.
+func Ptsname(f *os.File) (string, error) {
+	var n int
+
+	if err := Ioctl(f.Fd(), syscall.TIOCGPTN, uintptr(unsafe.Pointer(&n))); err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("/dev/pts/%d", n), nil
+}
+
+// CreateMasterAndConsole will open /dev/ptmx on the host and retreive the
+// pts name for use as the pty slave inside the container
+func CreateMasterAndConsole() (*os.File, string, error) {
+	master, err := os.OpenFile("/dev/ptmx", syscall.O_RDWR|syscall.O_NOCTTY|syscall.O_CLOEXEC, 0)
+	if err != nil {
+		return nil, "", err
+	}
+	console, err := Ptsname(master)
+	if err != nil {
+		return nil, "", err
+	}
+	if err := Unlockpt(master); err != nil {
+		return nil, "", err
+	}
+	return master, console, nil
+}
+
+// OpenPtmx opens /dev/ptmx, i.e. the PTY master.
+func OpenPtmx() (*os.File, error) {
+	// O_NOCTTY and O_CLOEXEC are not present in os package so we use the syscall's one for all.
+	return os.OpenFile("/dev/ptmx", syscall.O_RDONLY|syscall.O_NOCTTY|syscall.O_CLOEXEC, 0)
+}
+
+// OpenTerminal is a clone of os.OpenFile without the O_CLOEXEC
+// used to open the pty slave inside the container namespace
+func OpenTerminal(name string, flag int) (*os.File, error) {
+	r, e := syscall.Open(name, flag, 0)
+	if e != nil {
+		return nil, &os.PathError{"open", name, e}
+	}
+	return os.NewFile(uintptr(r), name), nil
+}
+
+func Ioctl(fd uintptr, flag, data uintptr) error {
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, flag, data); err != 0 {
+		return err
+	}
+
+	return nil
 }

namespaces/exec.go

@@ -11,6 +11,7 @@ import (
 	"github.com/docker/libcontainer/cgroups"
 	"github.com/docker/libcontainer/cgroups/fs"
 	"github.com/docker/libcontainer/cgroups/systemd"
+	consolePkg "github.com/docker/libcontainer/console"
 	"github.com/docker/libcontainer/network"
 	"github.com/docker/libcontainer/syncpipe"
 	"github.com/dotcloud/docker/pkg/system"
@@ -36,7 +37,7 @@ func Exec(container *libcontainer.Config, term Terminal, rootfs, dataPath string
 	defer syncPipe.Close()
 
 	if container.Tty {
-		master, console, err = system.CreateMasterAndConsole()
+		master, console, err = consolePkg.CreateMasterAndConsole()
 		if err != nil {
 			return -1, err
 		}
@@ -110,6 +111,7 @@ func Exec(container *libcontainer.Config, term Terminal, rootfs, dataPath string
 			return -1, err
 		}
 	}
+
 	return command.ProcessState.Sys().(syscall.WaitStatus).ExitStatus(), nil
 }
 
@@ -145,7 +147,11 @@ func DefaultCreateCommand(container *libcontainer.Config, console, rootfs, dataP
 	command.Dir = rootfs
 	command.Env = append(os.Environ(), env...)
 
-	system.SetCloneFlags(command, uintptr(GetNamespaceFlags(container.Namespaces)))
+	if command.SysProcAttr == nil {
+		command.SysProcAttr = &syscall.SysProcAttr{}
+	}
+	command.SysProcAttr.Cloneflags = uintptr(GetNamespaceFlags(container.Namespaces))
+
 	command.SysProcAttr.Pdeathsig = syscall.SIGKILL
 	command.ExtraFiles = []*os.File{pipe}
 
@@ -157,11 +163,14 @@ func DefaultCreateCommand(container *libcontainer.Config, console, rootfs, dataP
 func SetupCgroups(container *libcontainer.Config, nspid int) (cgroups.ActiveCgroup, error) {
 	if container.Cgroups != nil {
 		c := container.Cgroups
+
 		if systemd.UseSystemd() {
 			return systemd.Apply(c, nspid)
 		}
+
 		return fs.Apply(c, nspid)
 	}
+
 	return nil, nil
 }
 

namespaces/execin.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/docker/libcontainer"
 	"github.com/docker/libcontainer/label"
-	"github.com/dotcloud/docker/pkg/system"
+	"github.com/docker/libcontainer/system"
 )
 
 // ExecIn uses an existing pid and joins the pid's namespaces with the new command.

network/netns.go

@@ -7,7 +7,7 @@ import (
 	"os"
 	"syscall"
 
-	"github.com/dotcloud/docker/pkg/system"
+	"github.com/docker/libcontainer/system"
 )
 
 //  crosbymichael: could make a network strategy that instead of returning veth pair names it returns a pid to an existing network namespace
@@ -23,12 +23,15 @@ func (v *NetNS) Initialize(config *Network, networkState *NetworkState) error {
 	if networkState.NsPath == "" {
 		return fmt.Errorf("nspath does is not specified in NetworkState")
 	}
+
 	f, err := os.OpenFile(networkState.NsPath, os.O_RDONLY, 0)
 	if err != nil {
 		return fmt.Errorf("failed get network namespace fd: %v", err)
 	}
+
 	if err := system.Setns(f.Fd(), syscall.CLONE_NEWNET); err != nil {
 		return fmt.Errorf("failed to setns current network namespace: %v", err)
 	}
+
 	return nil
 }

system/linux.go

@@ -0,0 +1,17 @@
+// +build linux
+
+package system
+
+import (
+	"os/exec"
+	"syscall"
+)
+
+func Execv(cmd string, args []string, env []string) error {
+	name, err := exec.LookPath(cmd)
+	if err != nil {
+		return err
+	}
+
+	return syscall.Exec(name, args, env)
+}

system/proc.go

@@ -0,0 +1,27 @@
+package system
+
+import (
+	"io/ioutil"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// look in /proc to find the process start time so that we can verify
+// that this pid has started after ourself
+func GetProcessStartTime(pid int) (string, error) {
+	data, err := ioutil.ReadFile(filepath.Join("/proc", strconv.Itoa(pid), "stat"))
+	if err != nil {
+		return "", err
+	}
+
+	parts := strings.Split(string(data), " ")
+	// the starttime is located at pos 22
+	// from the man page
+	//
+	// starttime %llu (was %lu before Linux 2.6)
+	// (22)  The  time the process started after system boot.  In kernels before Linux 2.6, this
+	// value was expressed in jiffies.  Since Linux 2.6, the value is expressed in  clock  ticks
+	// (divide by sysconf(_SC_CLK_TCK)).
+	return parts[22-1], nil // starts at 1
+}

system/setns_linux.go

@@ -0,0 +1,29 @@
+package system
+
+import (
+	"fmt"
+	"runtime"
+	"syscall"
+)
+
+// Via http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7b21fddd087678a70ad64afc0f632e0f1071b092
+//
+// We need different setns values for the different platforms and arch
+// We are declaring the macro here because the SETNS syscall does not exist in th stdlib
+var setNsMap = map[string]uintptr{
+	"linux/amd64": 308,
+}
+
+func Setns(fd uintptr, flags uintptr) error {
+	ns, exists := setNsMap[fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH)]
+	if !exists {
+		return fmt.Errorf("unsupported platform %s/%s", runtime.GOOS, runtime.GOARCH)
+	}
+
+	_, _, err := syscall.RawSyscall(ns, fd, flags, 0)
+	if err != 0 {
+		return err
+	}
+
+	return nil
+}