feat(term): add cross-platform console state-aware support (#29)

* feat(term): add cross-platform console state-aware support

This basically ports https://github.com/golang/term but without the VT
terminal stuff, ANSI codes, and exports platform-specific terminal
state. On Unix, the state is `unix.Termios`, and on Windows, it's a
`uint32` representing the console mode
https://learn.microsoft.com/en-us/windows/console/getconsolemode.

* feat(term): support setting terminal state (#30)

* feat(term): use uintptr instead of int

Simplify API usage

term/term.go

@@ -0,0 +1,49 @@
+package term
+
+// State contains platform-specific state of a terminal.
+type State struct {
+	state
+}
+
+// IsTerminal returns whether the given file descriptor is a terminal.
+func IsTerminal(fd uintptr) bool {
+	return isTerminal(fd)
+}
+
+// MakeRaw puts the terminal connected to the given file descriptor into raw
+// mode and returns the previous state of the terminal so that it can be
+// restored.
+func MakeRaw(fd uintptr) (*State, error) {
+	return makeRaw(fd)
+}
+
+// GetState returns the current state of a terminal which may be useful to
+// restore the terminal after a signal.
+func GetState(fd uintptr) (*State, error) {
+	return getState(fd)
+}
+
+// SetState sets the given state of the terminal.
+func SetState(fd uintptr, state *State) error {
+	return setState(fd, state)
+}
+
+// Restore restores the terminal connected to the given file descriptor to a
+// previous state.
+func Restore(fd uintptr, oldState *State) error {
+	return restore(fd, oldState)
+}
+
+// GetSize returns the visible dimensions of the given terminal.
+//
+// These dimensions don't include any scrollback buffer height.
+func GetSize(fd uintptr) (width, height int, err error) {
+	return getSize(fd)
+}
+
+// ReadPassword reads a line of input from a terminal without local echo.  This
+// is commonly used for inputting passwords and other sensitive data. The slice
+// returned does not include the \n.
+func ReadPassword(fd uintptr) ([]byte, error) {
+	return readPassword(fd)
+}

term/term_other.go

@@ -0,0 +1,39 @@
+//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !zos && !windows && !solaris && !plan9
+// +build !aix,!darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd,!zos,!windows,!solaris,!plan9
+
+package term
+
+import (
+	"fmt"
+	"runtime"
+)
+
+type state struct{}
+
+func isTerminal(fd uintptr) bool {
+	return false
+}
+
+func makeRaw(fd uintptr) (*State, error) {
+	return nil, fmt.Errorf("terminal: MakeRaw not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+func getState(fd uintptr) (*State, error) {
+	return nil, fmt.Errorf("terminal: GetState not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+func restore(fd uintptr, state *State) error {
+	return fmt.Errorf("terminal: Restore not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+func getSize(fd uintptr) (width, height int, err error) {
+	return 0, 0, fmt.Errorf("terminal: GetSize not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+func setState(fd uintptr, state *State) error {
+	return fmt.Errorf("terminal: SetState not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+func readPassword(fd uintptr) ([]byte, error) {
+	return nil, fmt.Errorf("terminal: ReadPassword not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}

term/term_test.go

@@ -0,0 +1,37 @@
+package term_test
+
+import (
+	"os"
+	"runtime"
+	"testing"
+
+	"github.com/charmbracelet/x/term"
+)
+
+func TestIsTerminalTempFile(t *testing.T) {
+	file, err := os.CreateTemp("", "TestIsTerminalTempFile")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+	defer file.Close()
+
+	if term.IsTerminal(file.Fd()) {
+		t.Fatalf("IsTerminal unexpectedly returned true for temporary file %s", file.Name())
+	}
+}
+
+func TestIsTerminalTerm(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skipf("unknown terminal path for GOOS %v", runtime.GOOS)
+	}
+	file, err := os.OpenFile("/dev/ptmx", os.O_RDWR, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer file.Close()
+
+	if !term.IsTerminal(file.Fd()) {
+		t.Fatalf("IsTerminal unexpectedly returned false for terminal file %s", file.Name())
+	}
+}

term/term_unix.go

@@ -0,0 +1,96 @@
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
+
+package term
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+type state struct {
+	unix.Termios
+}
+
+func isTerminal(fd uintptr) bool {
+	_, err := unix.IoctlGetTermios(int(fd), ioctlReadTermios)
+	return err == nil
+}
+
+func makeRaw(fd uintptr) (*State, error) {
+	termios, err := unix.IoctlGetTermios(int(fd), ioctlReadTermios)
+	if err != nil {
+		return nil, err
+	}
+
+	oldState := State{state{Termios: *termios}}
+
+	// This attempts to replicate the behaviour documented for cfmakeraw in
+	// the termios(3) manpage.
+	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
+	termios.Oflag &^= unix.OPOST
+	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
+	termios.Cflag &^= unix.CSIZE | unix.PARENB
+	termios.Cflag |= unix.CS8
+	termios.Cc[unix.VMIN] = 1
+	termios.Cc[unix.VTIME] = 0
+	if err := unix.IoctlSetTermios(int(fd), ioctlWriteTermios, termios); err != nil {
+		return nil, err
+	}
+
+	return &oldState, nil
+}
+
+func setState(fd uintptr, state *State) error {
+	var termios *unix.Termios
+	if state != nil {
+		termios = &state.Termios
+	}
+	return unix.IoctlSetTermios(int(fd), ioctlWriteTermios, termios)
+}
+
+func getState(fd uintptr) (*State, error) {
+	termios, err := unix.IoctlGetTermios(int(fd), ioctlReadTermios)
+	if err != nil {
+		return nil, err
+	}
+
+	return &State{state{Termios: *termios}}, nil
+}
+
+func restore(fd uintptr, state *State) error {
+	return unix.IoctlSetTermios(int(fd), ioctlWriteTermios, &state.Termios)
+}
+
+func getSize(fd uintptr) (width, height int, err error) {
+	ws, err := unix.IoctlGetWinsize(int(fd), unix.TIOCGWINSZ)
+	if err != nil {
+		return 0, 0, err
+	}
+	return int(ws.Col), int(ws.Row), nil
+}
+
+// passwordReader is an io.Reader that reads from a specific file descriptor.
+type passwordReader int
+
+func (r passwordReader) Read(buf []byte) (int, error) {
+	return unix.Read(int(r), buf)
+}
+
+func readPassword(fd uintptr) ([]byte, error) {
+	termios, err := unix.IoctlGetTermios(int(fd), ioctlReadTermios)
+	if err != nil {
+		return nil, err
+	}
+
+	newState := *termios
+	newState.Lflag &^= unix.ECHO
+	newState.Lflag |= unix.ICANON | unix.ISIG
+	newState.Iflag |= unix.ICRNL
+	if err := unix.IoctlSetTermios(int(fd), ioctlWriteTermios, &newState); err != nil {
+		return nil, err
+	}
+
+	defer unix.IoctlSetTermios(int(fd), ioctlWriteTermios, termios)
+
+	return readPasswordLine(passwordReader(fd))
+}

term/term_unix_bsd.go

@@ -0,0 +1,11 @@
+//go:build darwin || dragonfly || freebsd || netbsd || openbsd
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package term
+
+import "golang.org/x/sys/unix"
+
+const (
+	ioctlReadTermios  = unix.TIOCGETA
+	ioctlWriteTermios = unix.TIOCSETA
+)

term/term_unix_other.go

@@ -0,0 +1,11 @@
+//go:build aix || linux || solaris || zos
+// +build aix linux solaris zos
+
+package term
+
+import "golang.org/x/sys/unix"
+
+const (
+	ioctlReadTermios  = unix.TCGETS
+	ioctlWriteTermios = unix.TCSETS
+)

term/term_windows.go

@@ -0,0 +1,86 @@
+//go:build windows
+// +build windows
+
+package term
+
+import (
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+type state struct {
+	Mode uint32
+}
+
+func isTerminal(fd uintptr) bool {
+	var st uint32
+	err := windows.GetConsoleMode(windows.Handle(fd), &st)
+	return err == nil
+}
+
+func makeRaw(fd uintptr) (*State, error) {
+	var st uint32
+	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
+		return nil, err
+	}
+	raw := st &^ (windows.ENABLE_ECHO_INPUT | windows.ENABLE_PROCESSED_INPUT | windows.ENABLE_LINE_INPUT | windows.ENABLE_PROCESSED_OUTPUT)
+	if err := windows.SetConsoleMode(windows.Handle(fd), raw); err != nil {
+		return nil, err
+	}
+	return &State{state{st}}, nil
+}
+
+func setState(fd uintptr, state *State) error {
+	var mode uint32
+	if state != nil {
+		mode = state.Mode
+	}
+	return windows.SetConsoleMode(windows.Handle(fd), mode)
+}
+
+func getState(fd uintptr) (*State, error) {
+	var st uint32
+	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
+		return nil, err
+	}
+	return &State{state{st}}, nil
+}
+
+func restore(fd uintptr, state *State) error {
+	return windows.SetConsoleMode(windows.Handle(fd), state.Mode)
+}
+
+func getSize(fd uintptr) (width, height int, err error) {
+	var info windows.ConsoleScreenBufferInfo
+	if err := windows.GetConsoleScreenBufferInfo(windows.Handle(fd), &info); err != nil {
+		return 0, 0, err
+	}
+	return int(info.Window.Right - info.Window.Left + 1), int(info.Window.Bottom - info.Window.Top + 1), nil
+}
+
+func readPassword(fd uintptr) ([]byte, error) {
+	var st uint32
+	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
+		return nil, err
+	}
+	old := st
+
+	st &^= (windows.ENABLE_ECHO_INPUT | windows.ENABLE_LINE_INPUT)
+	st |= (windows.ENABLE_PROCESSED_OUTPUT | windows.ENABLE_PROCESSED_INPUT)
+	if err := windows.SetConsoleMode(windows.Handle(fd), st); err != nil {
+		return nil, err
+	}
+
+	defer windows.SetConsoleMode(windows.Handle(fd), old)
+
+	var h windows.Handle
+	p, _ := windows.GetCurrentProcess()
+	if err := windows.DuplicateHandle(p, windows.Handle(fd), p, &h, 0, false, windows.DUPLICATE_SAME_ACCESS); err != nil {
+		return nil, err
+	}
+
+	f := os.NewFile(uintptr(h), "stdin")
+	defer f.Close()
+	return readPasswordLine(f)
+}

term/util.go

@@ -0,0 +1,47 @@
+package term
+
+import (
+	"io"
+	"runtime"
+)
+
+// readPasswordLine reads from reader until it finds \n or io.EOF.
+// The slice returned does not include the \n.
+// readPasswordLine also ignores any \r it finds.
+// Windows uses \r as end of line. So, on Windows, readPasswordLine
+// reads until it finds \r and ignores any \n it finds during processing.
+func readPasswordLine(reader io.Reader) ([]byte, error) {
+	var buf [1]byte
+	var ret []byte
+
+	for {
+		n, err := reader.Read(buf[:])
+		if n > 0 {
+			switch buf[0] {
+			case '\b':
+				if len(ret) > 0 {
+					ret = ret[:len(ret)-1]
+				}
+			case '\n':
+				if runtime.GOOS != "windows" {
+					return ret, nil
+				}
+				// otherwise ignore \n
+			case '\r':
+				if runtime.GOOS == "windows" {
+					return ret, nil
+				}
+				// otherwise ignore \r
+			default:
+				ret = append(ret, buf[0])
+			}
+			continue
+		}
+		if err != nil {
+			if err == io.EOF && len(ret) > 0 {
+				return ret, nil
+			}
+			return ret, err
+		}
+	}
+}