Support auto-detection of input devices via fbink_input (#11807)

* Kobo: Drop a bunch of if ladder crap and switch to auto-detection of input devices via fbink_input
* Kindle: Drop an even larger bundle of crap to do the same ;p. (re: #11392)
* ExternalKeyboard: Switch to fbink_input to whitelist keyboards instead of the manual parsing of caps via its FindKeyboard class
* Input: Extended open/close wrappers to handle logging & tracking of dupe open/close calls.

plugins/externalkeyboard.koplugin/main.lua

@@ -1,5 +1,4 @@
 local Event = require("ui/event")
-local FindKeyboard = require("find-keyboard")
 local Device =  require("device")
 local InfoMessage = require("ui/widget/infomessage")
 local InputText = require("ui/widget/inputtext")
@@ -14,6 +13,7 @@ local _ = require("gettext")
 local ffi = require("ffi")
 local C = ffi.C
 require("ffi/posix_h")
+require("ffi/fbink_input_h")
 
 -- The include/linux/usb/role.h calls the USB roles "host" and "device".
 local USB_ROLE_DEVICE = "device"
@@ -224,18 +224,17 @@ function ExternalKeyboard:onExit()
     end
 end
 
-function ExternalKeyboard:_onEvdevInputInsert(evdev)
-    self:setupKeyboard("/dev/input/event" .. tostring(evdev))
+function ExternalKeyboard:_onEvdevInputInsert(event_path)
+    self:setupKeyboard(event_path)
 end
 
-function ExternalKeyboard:onEvdevInputInsert(evdev)
+function ExternalKeyboard:onEvdevInputInsert(path)
     -- Leave time for the kernel to actually create the device
-    UIManager:scheduleIn(0.5, self._onEvdevInputInsert, self, evdev)
+    UIManager:scheduleIn(0.5, self._onEvdevInputInsert, self, path)
 end
 
-function ExternalKeyboard:_onEvdevInputRemove(evdev)
+function ExternalKeyboard:_onEvdevInputRemove(event_path)
     -- Check that a keyboard we know about really was disconnected. Another input device could've been unplugged.
-    local event_path = "/dev/input/event" .. tostring(evdev)
     if not ExternalKeyboard.keyboard_fds[event_path] then
         logger.dbg("ExternalKeyboard:onEvdevInputRemove:", event_path, "was not a keyboard we knew about")
         return
@@ -248,6 +247,9 @@ function ExternalKeyboard:_onEvdevInputRemove(evdev)
         return
     end
 
+    -- Close our Input handle on it
+    Device.input.close(event_path)
+
     ExternalKeyboard.keyboard_fds[event_path] = nil
     ExternalKeyboard.connected_keyboards = ExternalKeyboard.connected_keyboards - 1
     logger.dbg("ExternalKeyboard: USB keyboard", event_path, "was disconnected; total:", ExternalKeyboard.connected_keyboards)
@@ -277,34 +279,84 @@ function ExternalKeyboard:_onEvdevInputRemove(evdev)
     self:_broadcastDisconnected()
 end
 
+function ExternalKeyboard:onEvdevInputRemove(path)
+    UIManager:scheduleIn(0.5, self._onEvdevInputRemove, self, path)
+end
+
 ExternalKeyboard._broadcastDisconnected = UIManager:debounce(0.5, false, function()
     InputText.initInputEvents()
     UIManager:broadcastEvent(Event:new("PhysicalKeyboardDisconnected"))
 end)
 
+-- Implement FindKeyboard:find & check via FBInkInput
+local function findKeyboards()
+    local keyboards = {}
+
+    local FBInkInput = ffi.load("fbink_input")
+    local dev_count = ffi.new("size_t[1]")
+    local devices = FBInkInput.fbink_input_scan(C.INPUT_KEYBOARD, 0, C.SCAN_ONLY, dev_count)
+    if devices ~= nil then
+        for i = 0, tonumber(dev_count[0]) - 1 do
+            local dev = devices[i]
+            if dev.matched then
+                -- Check if it provides a DPad, too.
+                local has_dpad = bit.band(dev.type, C.INPUT_DPAD) ~= 0
+                table.insert(keyboards, { event_path = ffi.string(dev.path), has_dpad = has_dpad })
+            end
+        end
+        C.free(devices)
+    end
+
+    return keyboards
+end
+
+local function checkKeyboard(path)
+    local keyboard
+
+    local FBInkInput = ffi.load("fbink_input")
+    local dev = FBInkInput.fbink_input_check(path, C.INPUT_KEYBOARD, 0, C.SCAN_ONLY)
+    if dev ~= nil then
+        if dev.matched then
+            keyboard = {
+                event_path = ffi.string(dev.path),
+                has_dpad = bit.band(dev.type, C.INPUT_DPAD) ~= 0
+            }
+        end
+        C.free(dev)
+    end
+
+    return keyboard
+end
+
 -- The keyboard events with the same key codes would override the original events.
 -- That may cause embedded buttons to lose their original function and produce letters,
 -- as we cannot tell which device a key press comes from.
 function ExternalKeyboard:findAndSetupKeyboards()
-    local keyboards = FindKeyboard:find()
+    local keyboards = findKeyboards()
 
     -- A USB keyboard may be recognized as several devices under a hub. And several of them may
     -- have keyboard capabilities set. Yet, only one would emit the events. The solution is to open all of them.
     for __, keyboard_info in ipairs(keyboards) do
-        self:setupKeyboard(keyboard_info.event_path)
+        self:setupKeyboard(keyboard_info)
     end
 end
 
-function ExternalKeyboard:onEvdevInputRemove(evdev)
-    UIManager:scheduleIn(0.5, self._onEvdevInputRemove, self, evdev)
-end
+function ExternalKeyboard:setupKeyboard(data)
+    local keyboard_info
+    if type(data) == "table" then
+        -- We came from findAndSetupKeyboards, no need to-re-check the device
+        keyboard_info = data
+    else
+        -- We came from a USB hotplug event handler, check the specified path
+        local event_path = data
 
-function ExternalKeyboard:setupKeyboard(event_path)
-    local keyboard_info = FindKeyboard:check(event_path:match(".+/(.+)")) -- FindKeyboard only wants eventN, not the full path
-    if not keyboard_info then
-        logger.dbg("ExternalKeyboard:setupKeyboard:", event_path, "doesn't look like a keyboard")
-        return
+        keyboard_info = checkKeyboard(event_path)
+        if not keyboard_info then
+            logger.dbg("ExternalKeyboard:setupKeyboard:", event_path, "doesn't look like a keyboard")
+            return
+        end
     end
+
     local has_dpad_func = Device.hasDPad
 
     logger.dbg("ExternalKeyboard:setupKeyboard", keyboard_info.event_path, "has_dpad", keyboard_info.has_dpad)