Implement ttyname() in case /dev/tty is not available

Close #1266
Close #447

src/tui/light.go

@@ -32,6 +32,12 @@ var offsetRegexp *regexp.Regexp = regexp.MustCompile("\x1b\\[([0-9]+);([0-9]+)R"
 func openTtyIn() *os.File {
 	in, err := os.OpenFile(consoleDevice, syscall.O_RDONLY, 0)
 	if err != nil {
+		tty := ttyname()
+		if len(tty) > 0 {
+			if in, err := os.OpenFile(tty, syscall.O_RDONLY, 0); err == nil {
+				return in
+			}
+		}
 		fmt.Fprintln(os.Stderr, "Failed to open "+consoleDevice)
 		os.Exit(2)
 	}

src/tui/ttyname_unix.go

@@ -0,0 +1,31 @@
+// +build !windows
+
+package tui
+
+import (
+	"io/ioutil"
+	"syscall"
+)
+
+var devPrefixes = [...]string{"/dev/pts/", "/dev/"}
+
+func ttyname() string {
+	var stderr syscall.Stat_t
+	if syscall.Fstat(2, &stderr) != nil {
+		return ""
+	}
+
+	for _, prefix := range devPrefixes {
+		files, err := ioutil.ReadDir(prefix)
+		if err != nil {
+			continue
+		}
+
+		for _, file := range files {
+			if stat, ok := file.Sys().(*syscall.Stat_t); ok && stat.Rdev == stderr.Rdev {
+				return prefix + file.Name()
+			}
+		}
+	}
+	return ""
+}

src/tui/ttyname_windows.go

@@ -0,0 +1,7 @@
+// +build windows
+
+package tui
+
+func ttyname() string {
+	return ""
+}