Replace calls to `stty` with <termios.h> cgo

This removes the dependency on `stty` and is the standard POSIX way of
modifying terminal state. It requires cgo, so cross-compiling might not
be trivial. Otherwise there are no additional dependencies brought in,
and this already supports all POSIXish platforms.

Fixes #154.

client.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"regexp"
 	"strconv"
@@ -19,6 +18,7 @@ import (
 	"tildegit.org/sloum/bombadillo/http"
 	"tildegit.org/sloum/bombadillo/local"
 	"tildegit.org/sloum/bombadillo/telnet"
+	"tildegit.org/sloum/bombadillo/termios"
 )
 
 //------------------------------------------------\\
@@ -43,14 +43,7 @@ type client struct {
 //--------------------------------------------------\\
 
 func (c *client) GetSizeOnce() {
-	cmd := exec.Command("stty", "size")
-	cmd.Stdin = os.Stdin
-	out, err := cmd.Output()
-	if err != nil {
-		cui.Exit(5, "Fatal error: Unable to retrieve terminal size")
-	}
-	var h, w int
-	_, _ = fmt.Sscan(string(out), &h, &w)
+	var w, h = termios.GetWindowSize()
 	c.Height = h
 	c.Width = w
 }
@@ -61,14 +54,7 @@ func (c *client) GetSize() {
 	c.Draw()
 
 	for {
-		cmd := exec.Command("stty", "size")
-		cmd.Stdin = os.Stdin
-		out, err := cmd.Output()
-		if err != nil {
-			cui.Exit(5, "Fatal error: Unable to retrieve terminal size")
-		}
-		var h, w int
-		_, _ = fmt.Sscan(string(out), &h, &w)
+		var w, h = termios.GetWindowSize()
 		if h != c.Height || w != c.Width {
 			c.Height = h
 			c.Width = w

cui/cui.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+
+	"tildegit.org/sloum/bombadillo/termios"
 )
 
 var Shapes = map[string]string{
@@ -55,7 +57,7 @@ func Exit(exitCode int, msg string) {
 
 // InitTerm sets the terminal modes appropriate for Bombadillo
 func InitTerm() {
-	SetCharMode()
+	termios.SetCharMode()
 	Tput("smcup") // use alternate screen
 	Tput("rmam")  // turn off line wrapping
 }
@@ -64,7 +66,7 @@ func InitTerm() {
 func CleanupTerm() {
 	moveCursorToward("down", 500)
 	moveCursorToward("right", 500)
-	SetLineMode()
+	termios.SetLineMode()
 
 	fmt.Print("\n")
 	fmt.Print("\033[?25h") // reenables cursor blinking
@@ -98,7 +100,7 @@ func Getch() rune {
 }
 
 func GetLine(prefix string) (string, error) {
-	SetLineMode()
+	termios.SetLineMode()
 
 	reader := bufio.NewReader(os.Stdin)
 	fmt.Print(prefix)
@@ -107,32 +109,10 @@ func GetLine(prefix string) (string, error) {
 		return "", err
 	}
 
-	SetCharMode()
+	termios.SetCharMode()
 	return text[:len(text)-1], nil
 }
 
-func SetCharMode() {
-	cmd := exec.Command("stty", "cbreak", "-echo")
-	cmd.Stdin = os.Stdin
-	cmd.Stdout = os.Stdout
-	err := cmd.Run()
-	if err != nil {
-		panic(err)
-	}
-
-	fmt.Print("\033[?25l")
-}
-
-func SetLineMode() {
-	cmd := exec.Command("stty", "-cbreak", "echo")
-	cmd.Stdin = os.Stdin
-	cmd.Stdout = os.Stdout
-	err := cmd.Run()
-	if err != nil {
-		panic(err)
-	}
-}
-
 func Tput(opt string) {
 	cmd := exec.Command("tput", opt)
 	cmd.Stdin = os.Stdin

termios/termios.go

@@ -0,0 +1,42 @@
+// +build cgo
+
+package termios
+
+/*
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <termios.h>
+// NOTE: ioctl() is variadic so cgo requires a wrapper
+int getWinsize(struct winsize* ws) {
+	return ioctl(STDOUT_FILENO, TIOCGWINSZ, ws);
+}
+*/
+import "C"
+
+func GetWindowSize() (int, int) {
+	var value C.struct_winsize
+	C.getWinsize(&value)
+	return int(value.ws_col), int(value.ws_row)
+}
+
+func getTermios() C.struct_termios {
+	var termios C.struct_termios
+	C.tcgetattr(C.STDIN_FILENO, &termios)
+	return termios
+}
+
+func setTermios(termios C.struct_termios) {
+	C.tcsetattr(C.STDIN_FILENO, C.TCSAFLUSH, &termios)
+}
+
+func SetCharMode() {
+	var t = getTermios()
+	t.c_lflag = t.c_lflag &^ (C.ICANON | C.ECHO)
+	setTermios(t)
+}
+
+func SetLineMode() {
+	var t = getTermios()
+	t.c_lflag = t.c_lflag | (C.ICANON | C.ECHO)
+	setTermios(t)
+}