wifi-detect.uc is writing a new board.json on every boot

[R.]

> This is happening on both of my Cudy WR3000 devices running 25.15.5.
> Flash wearing could be a thing. Commenting out the following block stops the writes.
> 
> if (!is_equal(prev_board_data, board_data)) {
>     let new_file = board_file + ".new";
>     unlink(new_file);
>     let f = open(new_file, "wx");
>     if (!f)
>         exit(1);
>     f.write(sprintf("%.J\n", board_data));
>     f.close();
>     rename(new_file, board_file);
> }
> 
> A quick look at the is_equal function showed no obvious issues. I'll set up a modified wifi-detect.uc to log the before and after contents at boot.
> The issue was found with:
> sleep 90 && touch -m /etc/timestamp && ubus -S call system reboot
> find /overlay/upper -newer /etc/timestamp
> 

Here is the result by replacing the above block with:

if (!is_equal(prev_board_data, board_data)) {
    const prev_board_json = open("/tmp/board.json.prev", "w");
    const curr_board_json = open("/tmp/board.json.curr", "w");

    prev_board_json?.write(sprintf("%.J\n", prev_board_data));
    curr_board_json?.write(sprintf("%.J\n", board_data));

    prev_board_json?.close();
    curr_board_json?.close();
}

diff -u board.json.prev board.json.curr
--- board.json.prev
+++ board.json.curr
@@ -27,60 +27,5 @@
 		}
 	},
 	"wlan": {
-		"phy0": {
-			"path": "platform/soc/18000000.wifi",
-			"info": {
-				"antenna_rx": 3,
-				"antenna_tx": 3,
-				"bands": {
-					"2G": {
-						"ht": true,
-						"he": true,
-						"max_width": 40,
-						"modes": [
-							"NOHT",
-							"HT20",
-							"HE20",
-							"HT40",
-							"HE40"
-						],
-						"default_channel": 1
-					}
-				},
-				"radios": [
-				]
-			}
-		},
-		"phy1": {
-			"path": "platform/soc/18000000.wifi+1",
-			"info": {
-				"antenna_rx": 3,
-				"antenna_tx": 3,
-				"bands": {
-					"5G": {
-						"ht": true,
-						"vht": true,
-						"he": true,
-						"max_width": 160,
-						"modes": [
-							"NOHT",
-							"HT20",
-							"VHT20",
-							"HE20",
-							"HT40",
-							"VHT40",
-							"HE40",
-							"VHT80",
-							"HE80",
-							"VHT160",
-							"HE160"
-						],
-						"default_channel": 36
-					}
-				},
-				"radios": [
-				]
-			}
-		}
 	}
 }

As you can see, wifi-detect.uc, when first called after a boot, won't be able to detect wifi devices through NL80211_CMD_GET_WIPHY, resulting in not just one, but TWO writes per boot (one with no devices and another with the devices).

Possible solution:

if (!is_equal(prev_board_data, board_data) && length(board_data.wlan)) {
}

This needs to be addressed asap. I em pretty sure this isn't just happening on the Cudy WR3000. Flashes are getting wear for no good reason.