unix: add ioctl functions on Darwin

Add IoctlGetInt/IoctlSetInt, IoctlGetTermios/IoctlSetTermios and
IoctlGetWinsize/IoctlSetWinsize on Darwin. These are similar to the
already existing implementations on Linux and Solaris.

Generated on Mac OS 10.11 (Darwin 15.6.0).

Change-Id: I2d4cc957c840836fcc2ccb71c67631420f4a2eb1
Reviewed-on: https://go-review.googlesource.com/52410
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

unix/syscall_darwin.go

@@ -195,6 +195,45 @@ func Getfsstat(buf []Statfs_t, flags int) (n int, err error) {
 
 func Kill(pid int, signum syscall.Signal) (err error) { return kill(pid, int(signum), 1) }
 
+//sys	ioctl(fd int, req uint, arg uintptr) (err error)
+
+// ioctl itself should not be exposed directly, but additional get/set
+// functions for specific types are permissible.
+
+// IoctlSetInt performs an ioctl operation which sets an integer value
+// on fd, using the specified request number.
+func IoctlSetInt(fd int, req uint, value int) error {
+	return ioctl(fd, req, uintptr(value))
+}
+
+func IoctlSetWinsize(fd int, req uint, value *Winsize) error {
+	return ioctl(fd, req, uintptr(unsafe.Pointer(value)))
+}
+
+func IoctlSetTermios(fd int, req uint, value *Termios) error {
+	return ioctl(fd, req, uintptr(unsafe.Pointer(value)))
+}
+
+// IoctlGetInt performs an ioctl operation which gets an integer value
+// from fd, using the specified request number.
+func IoctlGetInt(fd int, req uint) (int, error) {
+	var value int
+	err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
+	return value, err
+}
+
+func IoctlGetWinsize(fd int, req uint) (*Winsize, error) {
+	var value Winsize
+	err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
+	return &value, err
+}
+
+func IoctlGetTermios(fd int, req uint) (*Termios, error) {
+	var value Termios
+	err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
+	return &value, err
+}
+
 /*
  * Exposed directly
  */