diff --git a/cmd/containerd-shim/console.go b/cmd/containerd-shim/console.go index 1d3262d..96d9ebc 100644 --- a/cmd/containerd-shim/console.go +++ b/cmd/containerd-shim/console.go @@ -16,6 +16,9 @@ func newConsole(uid, gid int) (*os.File, string, 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 @@ -32,6 +35,29 @@ func newConsole(uid, gid int) (*os.File, string, error) { return master, console, 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 +} + func ioctl(fd uintptr, flag, data uintptr) error { if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, flag, data); err != 0 { return err