nickel_conf: handle missing file/key/section

frontend/device/kobo/nickel_conf.lua

@@ -13,24 +13,39 @@ local re_PowerOptionsSection = "^%[PowerOptions%]%s*"
 local re_AnySection = "^%[.*%]%s*"
 
 function NickelConf.frontLightLevel.get()
+
+    local new_intensity
     local correct_section = false
-    local kobo_conf = assert(io.open(kobo_conf_path, "r"))
-    for line in kobo_conf:lines() do
-        if string.match(line, re_AnySection) then
-            correct_section = false
-            if string.match(line, re_PowerOptionsSection) then
-                correct_section = true
-            end
-        end
-        if correct_section then
-            new_intensity = string.match(line, re_FrontLightLevel)
-            if new_intensity then
-                new_intensity = tonumber(new_intensity)
-                break
+    local kobo_conf = io.open(kobo_conf_path, "r")
+
+    if kobo_conf then
+        for line in kobo_conf:lines() do
+            if string.match(line, re_AnySection) then
+                correct_section = false
+                if string.match(line, re_PowerOptionsSection) then
+                    correct_section = true
+                end
+            end
+            if correct_section then
+                new_intensity = string.match(line, re_FrontLightLevel)
+                if new_intensity then
+                    new_intensity = tonumber(new_intensity)
+                    break
+                end
             end
         end
+        kobo_conf:close()
     end
-    kobo_conf:close()
+
+    if not new_intensity then
+        local Device = require("device")
+        local powerd = Device:getPowerDevice()
+        local fallback_FrontLightLevel = powerd.flIntensity or 1
+
+        assert(NickelConf.frontLightLevel.set(fallback_FrontLightLevel))
+        return fallback_FrontLightLevel
+    end
+
     return new_intensity
 end
 
@@ -38,33 +53,59 @@ function NickelConf.frontLightLevel.set(new_intensity)
 	assert(new_intensity >= 0 and new_intensity <= 100,
 		"Wrong brightness value given!")
 
+    local kobo_conf
+    local old_intensity
+    local remaining_file = ""
     local lines = {}
+    local current_position
     local correct_section = false
-    local kobo_conf = assert(io.open(kobo_conf_path, "r"))
-    for line in kobo_conf:lines() do
-        if string.match(line, re_AnySection) then
-            correct_section = false
-            if string.match(line, re_PowerOptionsSection) then
-                correct_section = true
-            end
-        end
-        old_intensity = string.match(line, re_FrontLightLevel)
-        if correct_section and old_intensity then
-            lines[#lines + 1] = string.gsub(line, re_BrightnessValue, new_intensity, 1)
-            remaining_file = kobo_conf:read("*a")
-            break
-        else
-            lines[#lines + 1] = line
-        end
-    end
-    kobo_conf:close()
+    local modified_brightness = false
 
-    kobo_conf = assert(io.open(kobo_conf_path, "w"))
-    for i, line in ipairs(lines) do
-      kobo_conf:write(line, "\n")
+    kobo_conf = io.open(kobo_conf_path, "r")
+    if kobo_conf then
+        for line in kobo_conf:lines() do
+            if string.match(line, re_AnySection) then
+                if correct_section then
+                    -- found a new section after having found the correct one,
+                    -- therefore the key was missing: let the code below add it
+                    kobo_conf:seek("set", current_position)
+                    break
+                end
+                if string.match(line, re_PowerOptionsSection) then
+                    correct_section = true
+                end
+            end
+            old_intensity = string.match(line, re_FrontLightLevel)
+            if correct_section and old_intensity then
+                lines[#lines + 1] = string.gsub(line, re_BrightnessValue, new_intensity, 1)
+                modified_brightness = true
+                break
+            else
+                lines[#lines + 1] = line
+            end
+            current_position = kobo_conf:seek()
+        end
     end
-    kobo_conf:write(remaining_file)
-    kobo_conf:close()
+
+    if not modified_brightness then
+        if not correct_section then
+            lines[#lines + 1] = '[PowerOptions]'
+        end
+        lines[#lines + 1] = 'FrontLightLevel=' .. new_intensity
+    end
+
+    if kobo_conf then
+        remaining_file = kobo_conf:read("*a")
+        kobo_conf:close()
+    end
+
+    kobo_conf_w = assert(io.open(kobo_conf_path, "w"))
+    for i, line in ipairs(lines) do
+      kobo_conf_w:write(line, "\n")
+    end
+    kobo_conf_w:write(remaining_file)
+    kobo_conf_w:close()
+    return true
 end
 
 return NickelConf

frontend/ui/uimanager.lua

@@ -6,7 +6,6 @@ local Geom = require("ui/geometry")
 local util = require("ffi/util")
 local DEBUG = require("dbg")
 local _ = require("gettext")
-local NickelConf = require("device/kobo/nickel_conf")
 
 local MILLION = 1000000
 
@@ -63,9 +62,11 @@ function UIManager:init()
         end
         local kobo_light_on_start = tonumber(KOBO_LIGHT_ON_START)
         if kobo_light_on_start then
+            local new_intensity
             if kobo_light_on_start >= 0 then
                 new_intensity = math.min(kobo_light_on_start, 100)
             elseif kobo_light_on_start == -2 then
+                local NickelConf = require("device/kobo/nickel_conf")
                 new_intensity = NickelConf.frontLightLevel:get()
             end
             if new_intensity then