Use termios via CGO only on Linux

Signed-off-by: Yohei Ueda <yohei@jp.ibm.com>

term/tc_linux_cgo.go

@@ -0,0 +1,47 @@
+// +build linux,cgo
+
+package term
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// #include <termios.h>
+import "C"
+
+type Termios syscall.Termios
+
+// MakeRaw put 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) {
+	var oldState State
+	if err := tcget(fd, &oldState.termios); err != 0 {
+		return nil, err
+	}
+
+	newState := oldState.termios
+
+	C.cfmakeraw((*C.struct_termios)(unsafe.Pointer(&newState)))
+	if err := tcset(fd, &newState); err != 0 {
+		return nil, err
+	}
+	return &oldState, nil
+}
+
+func tcget(fd uintptr, p *Termios) syscall.Errno {
+	ret, err := C.tcgetattr(C.int(fd), (*C.struct_termios)(unsafe.Pointer(p)))
+	if ret != 0 {
+		return err.(syscall.Errno)
+	}
+	return 0
+}
+
+func tcset(fd uintptr, p *Termios) syscall.Errno {
+	ret, err := C.tcsetattr(C.int(fd), C.TCSANOW, (*C.struct_termios)(unsafe.Pointer(p)))
+	if ret != 0 {
+		return err.(syscall.Errno)
+	}
+	return 0
+}