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