Add support for z/OS

Add an implementation of NewPty for the zos platform. The other
functions in console_zos.go exactly match those in console_unix.go.

There is no need for ptsname/unlockpt on z/OS, so tc_zos.go looks
just like the implementation for linux/solaris except for the
omission of those functions.

Signed-off-by: Neil Johnson <[email protected]>

Author: najohnsn

console_zos.go

@@ -0,0 +1,163 @@
+// +build zos
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package console
+
+import (
+	"fmt"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// NewPty creates a new pty pair
+// The master is returned as the first console and a string
+// with the path to the pty slave is returned as the second
+func NewPty() (Console, string, error) {
+	var f File
+	var err error
+	var slave string
+	for i := 0;; i++ {
+		ptyp := fmt.Sprintf("/dev/ptyp%04d", i)
+		f, err = os.OpenFile(ptyp, os.O_RDWR, 0600)
+		if err == nil {
+			slave = fmt.Sprintf("/dev/ttyp%04d", i)
+			break
+		}
+		if os.IsNotExist(err) {
+			return nil, "", err
+		}
+		// else probably Resource Busy
+	}
+	m, err := newMaster(f)
+	if err != nil {
+		return nil, "", err
+	}
+	return m, slave, nil
+}
+
+type master struct {
+	f        File
+	original *unix.Termios
+}
+
+func (m *master) Read(b []byte) (int, error) {
+	return m.f.Read(b)
+}
+
+func (m *master) Write(b []byte) (int, error) {
+	return m.f.Write(b)
+}
+
+func (m *master) Close() error {
+	return m.f.Close()
+}
+
+func (m *master) Resize(ws WinSize) error {
+	return tcswinsz(m.f.Fd(), ws)
+}
+
+func (m *master) ResizeFrom(c Console) error {
+	ws, err := c.Size()
+	if err != nil {
+		return err
+	}
+	return m.Resize(ws)
+}
+
+func (m *master) Reset() error {
+	if m.original == nil {
+		return nil
+	}
+	return tcset(m.f.Fd(), m.original)
+}
+
+func (m *master) getCurrent() (unix.Termios, error) {
+	var termios unix.Termios
+	if err := tcget(m.f.Fd(), &termios); err != nil {
+		return unix.Termios{}, err
+	}
+	return termios, nil
+}
+
+func (m *master) SetRaw() error {
+	rawState, err := m.getCurrent()
+	if err != nil {
+		return err
+	}
+	rawState = cfmakeraw(rawState)
+	rawState.Oflag = rawState.Oflag | unix.OPOST
+	return tcset(m.f.Fd(), &rawState)
+}
+
+func (m *master) DisableEcho() error {
+	rawState, err := m.getCurrent()
+	if err != nil {
+		return err
+	}
+	rawState.Lflag = rawState.Lflag &^ unix.ECHO
+	return tcset(m.f.Fd(), &rawState)
+}
+
+func (m *master) Size() (WinSize, error) {
+	return tcgwinsz(m.f.Fd())
+}
+
+func (m *master) Fd() uintptr {
+	return m.f.Fd()
+}
+
+func (m *master) Name() string {
+	return m.f.Name()
+}
+
+// checkConsole checks if the provided file is a console
+func checkConsole(f File) error {
+	var termios unix.Termios
+	if tcget(f.Fd(), &termios) != nil {
+		return ErrNotAConsole
+	}
+	return nil
+}
+
+func newMaster(f File) (Console, error) {
+	m := &master{
+		f: f,
+	}
+	t, err := m.getCurrent()
+	if err != nil {
+		return nil, err
+	}
+	m.original = &t
+	return m, nil
+}
+
+// ClearONLCR 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 ClearONLCR(fd uintptr) error {
+	return setONLCR(fd, false)
+}
+
+// SetONLCR sets the necessary tty_ioctl(4)s to ensure that a pty pair
+// created by us acts as intended for a terminal emulator.
+func SetONLCR(fd uintptr) error {
+	return setONLCR(fd, true)
+}

tc_unix.go

@@ -1,4 +1,4 @@
-// +build darwin freebsd linux netbsd openbsd solaris
+// +build darwin freebsd linux netbsd openbsd solaris zos
 
 /*
    Copyright The containerd Authors.

tc_zos.go

@@ -0,0 +1,26 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package console
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+const (
+	cmdTcGet = unix.TCGETS
+	cmdTcSet = unix.TCSETS
+)