Fix console cursor on BSDs in async context

Gemfile

@@ -9,4 +9,5 @@ group :development do
   gem "test-unit"
   gem "test-unit-ruby-core"
   gem 'rake-compiler'
+  gem "async"
 end

ext/io/console/console.c

@@ -96,6 +96,10 @@ extern VALUE rb_scheduler_timeout(struct timeval *timeout);
 # define rb_fiber_scheduler_make_timeout rb_scheduler_timeout
 #endif
 
+#ifdef HAVE_SYS_EVENT_H
+extern VALUE rb_fiber_scheduler_current(void);
+#endif
+
 #ifndef HAVE_RB_IO_DESCRIPTOR
 static int
 io_descriptor_fallback(VALUE io)
@@ -1695,12 +1699,30 @@ console_dev(int argc, VALUE *argv, VALUE klass)
         int fd;
         VALUE path = rb_obj_freeze(rb_str_new2(CONSOLE_DEVICE));
 
+	fd = -1;
+#ifdef HAVE_SYS_EVENT_H
+	VALUE scheduler = rb_fiber_scheduler_current();
+	if (!NIL_P(scheduler)) {
+		if (isatty(0)) {
+			fd = dup(0);
+			path = rb_obj_freeze(rb_str_new2("<STDIN>"));
+		} else if (isatty(1)) {
+			fd = dup(1);
+			path = rb_obj_freeze(rb_str_new2("<STDOUT>"));
+		} else if (isatty(2)) {
+			fd = dup(2);
+			path = rb_obj_freeze(rb_str_new2("<STDERR>"));
+		}
+	}
+#endif
+	if (fd == -1) {
 #ifdef CONSOLE_DEVICE_FOR_WRITING
-        fd = rb_cloexec_open(CONSOLE_DEVICE_FOR_WRITING, O_RDWR, 0);
-        if (fd < 0) return Qnil;
-        out = rb_io_open_descriptor(klass, fd, FMODE_WRITABLE | FMODE_SYNC, path, Qnil, NULL);
+        int writing_fd = rb_cloexec_open(CONSOLE_DEVICE_FOR_WRITING, O_RDWR, 0);
+        if (writing_fd < 0) return Qnil;
+        out = rb_io_open_descriptor(klass, writing_fd, FMODE_WRITABLE | FMODE_SYNC, path, Qnil, NULL);
 #endif
         fd = rb_cloexec_open(CONSOLE_DEVICE_FOR_READING, O_RDWR, 0);
+	}
         if (fd < 0) {
 #ifdef CONSOLE_DEVICE_FOR_WRITING
             rb_io_close(out);

ext/io/console/extconf.rb

@@ -41,6 +41,7 @@
 case ok
 when true
   have_header("sys/ioctl.h") if hdr
+  have_header("sys/event.h")
   # rb_check_hash_type: 1.9.3
   # rb_io_get_write_io: 1.9.1
   # rb_cloexec_open: 2.0.0

test/io/console/test_io_console.rb

@@ -169,9 +169,9 @@
   def test_noecho
     helper {|m, s|
       s.noecho {
-	assert_not_send([s, :echo?])
-	m.print "a"
-	sleep 0.1
+       assert_not_send([s, :echo?])
+       m.print "a"
+       sleep 0.1
       }
       m.print "b"
       assert_equal("b", m.readpartial(10))
@@ -367,6 +367,21 @@
     end
   end
 
+  def test_cursor_position_kqueue_regression
+    run_pty("#{<<~"begin;"}\n#{<<~'end;'}") do |r, w, _|
+      begin;
+        require "async"
+        require "io/console"
+
+        coords = Async { IO.console.cursor }.wait
+        p coords
+      end;
+      assert_equal("\e[6n", r.readpartial(5))
+      w.print("\e[12;34R"); w.flush
+      assert_equal([11, 33], eval(r.gets))
+    end
+  end
+
   def assert_ctrl(expect, cc, r, w)
     sleep 0.1
     w.print cc