Updated some documentation.

internal/console/native_linux.go

@@ -25,6 +25,7 @@ package console
 #include <libevdev/libevdev.h>
 #include <libevdev/libevdev-uinput.h>
 #include <linux/kd.h>
+#include <linux/vt.h>
 #include <sys/ioctl.h>
 #include <unistd.h>
 #include <errno.h>
@@ -36,6 +37,13 @@ static int console_state(int fd, int *mode, unsigned char *leds) {
     return 0;
 }
 
+static int console_usage(int fd, unsigned short *mask) {
+    struct vt_stat state;
+    if (ioctl(fd, VT_GETSTATE, &state) < 0) return -errno;
+    *mask = state.v_state;
+    return 0;
+}
+
 static int read_feedback(const struct libevdev_uinput *device, struct input_event *event) {
     ssize_t count = read(libevdev_uinput_get_fd(device), event, sizeof(*event));
     if (count < 0) return -errno;
@@ -69,6 +77,19 @@ func kernel_error(code C.int) error {
 	return syscall.Errno(-code)
 }
 
+func query_usage(path string) (uint16, error) {
+	file, err := os.OpenFile(path, os.O_RDONLY|syscall.O_NOCTTY, 0)
+	if err != nil {
+		return 0, err
+	}
+	defer file.Close()
+	var mask C.ushort
+	if err := kernel_error(C.console_usage(C.int(file.Fd()), &mask)); err != nil {
+		return 0, err
+	}
+	return uint16(mask), nil
+}
+
 func query_state(path string) (bool, bool, bool, error) {
 	file, err := os.OpenFile(path, os.O_RDONLY|syscall.O_NOCTTY, 0)
 	if err != nil {