koreader: fix that "isOnline" check was failing and preventing FTP access

hosts/common/programs/default.nix

@@ -12,7 +12,7 @@
     ./jellyfin-media-player.nix
     ./kitty
     ./komikku.nix
-    ./koreader.nix
+    ./koreader
     ./libreoffice.nix
     ./mpv.nix
     ./neovim.nix

hosts/common/programs/koreader.nix

@@ -1,11 +0,0 @@
-{ ... }:
-
-{
-  sane.programs.koreader = {
-    # koreader on aarch64 errors if there's no fonts directory (sandboxing thing, i guess)
-    fs.".local/share/fonts".dir = {};
-    # history, cache, dictionaries...
-    # could be more explicit if i symlinked the history.lua file to somewhere it can persist better.
-    persist.plaintext = [ ".config/koreader" ];
-  };
-}

hosts/common/programs/koreader/2-colin-NetworkManager-isConnected.lua

@@ -0,0 +1,39 @@
+-- as of 2023.05.1, koreader FTP browser always fails to load.
+-- it's convinced that it's offline, and asks to connect to wifi.
+-- this seems to be because of the following in <frontend/device/sdl/device.lua>:
+--
+-- function Device:initNetworkManager(NetworkMgr)
+--     function NetworkMgr:isWifiOn() return true end
+--     function NetworkMgr:isConnected()
+--         -- Pull the default gateway first, so we don't even try to ping anything if there isn't one...
+--         local default_gw = Device:getDefaultRoute()
+--         if not default_gw then
+--             return false
+--         end
+--         return 0 == os.execute("ping -c1 -w2 " .. default_gw .. " > /dev/null")
+--     end
+-- end
+--
+-- specifically, `os.execute` is not *expected* to return 0. it returns `true` on success:
+-- <https://www.lua.org/manual/5.3/manual.html#pdf-os.execute>
+-- this apparently changed from 5.1 -> 5.2
+
+local logger = require("logger")
+logger.info("applying colin patch")
+
+local Device = require("device")
+logger.info("Device:" .. tostring(Device))
+
+local orig_initNetworkManager = Device.initNetworkManager
+Device.initNetworkManager = function(self, NetworkMgr)
+  logger.info("Device:initNetworkManager")
+  orig_initNetworkManager(self, NetworkMgr)
+  function NetworkMgr:isConnected()
+    logger.info("mocked `NetworkMgr:isConnected` to return true")
+    return true
+    -- unpatch to show that the boolean form works
+    -- local rc = os.execute("ping -c1 -w2 10.78.79.1 > /dev/null")
+    -- logger.info("ping rc: " .. tostring(rc))
+    -- return rc
+  end
+end

hosts/common/programs/koreader/default.nix

@@ -0,0 +1,18 @@
+{ ... }:
+
+{
+  sane.programs.koreader = {
+    # koreader applies these lua "patches" at boot:
+    # - <https://github.com/koreader/koreader/wiki/User-patches>
+    # - TODO: upstream this patch to koreader
+    # fs.".config/koreader/patches".symlink.target = "${./.}";
+    fs.".config/koreader/patches/2-colin-NetworkManager-isConnected.lua".symlink.target = "${./2-colin-NetworkManager-isConnected.lua}";
+
+    # koreader on aarch64 errors if there's no fonts directory (sandboxing thing, i guess)
+    fs.".local/share/fonts".dir = {};
+
+    # history, cache, dictionaries...
+    # could be more explicit if i symlinked the history.lua file to somewhere it can persist better.
+    persist.plaintext = [ ".config/koreader" ];
+  };
+}