diff --git a/libcontainer/console_linux.go b/libcontainer/console_linux.go index 5bc2fd75..0ca59393 100644 --- a/libcontainer/console_linux.go +++ b/libcontainer/console_linux.go @@ -17,6 +17,9 @@ func NewConsole(uid, gid int) (Console, error) { if err != nil { return nil, err } + if err := saneTerminal(master); err != nil { + return nil, err + } console, err := ptsname(master) if err != nil { return nil, err @@ -143,3 +146,26 @@ func ptsname(f *os.File) (string, error) { } return fmt.Sprintf("/dev/pts/%d", n), nil } + +// saneTerminal sets the necessary tty_ioctl(4)s to ensure that a pty pair +// created by us acts normally. In particular, a not-very-well-known default of +// Linux unix98 ptys is that they have +onlcr by default. While this isn't a +// problem for terminal emulators, because we relay data from the terminal we +// also relay that funky line discipline. +func saneTerminal(terminal *os.File) error { + // Go doesn't have a wrapper for any of the termios ioctls. + var termios syscall.Termios + + if err := ioctl(terminal.Fd(), syscall.TCGETS, uintptr(unsafe.Pointer(&termios))); err != nil { + return fmt.Errorf("ioctl(tty, tcgets): %s", err.Error()) + } + + // Set -onlcr so we don't have to deal with \r. + termios.Oflag &^= syscall.ONLCR + + if err := ioctl(terminal.Fd(), syscall.TCSETS, uintptr(unsafe.Pointer(&termios))); err != nil { + return fmt.Errorf("ioctl(tty, tcsets): %s", err.Error()) + } + + return nil +}