hold on directory in filemanager can set the it as HOME directory

and this "HOME" directory will override the command line option passed to
koreader.

This patch implements #1434.

frontend/apps/filemanager/filemanager.lua

@@ -75,8 +75,7 @@ function FileManager:init()
 
     function file_chooser:onFileHold(file)
         --DEBUG("hold file", file)
-        self.file_dialog = ButtonDialog:new{
-            buttons = {
+        local buttons = {
             {
                 {
                     text = _("Copy"),
@@ -119,7 +118,21 @@ function FileManager:init()
                     end,
                 },
             },
-            },
+        }
+        if lfs.attributes(file, "mode") == "directory" then
+            local realpath = util.realpath(file)
+            table.insert(buttons, {
+                {
+                    text = _("Set as HOME directory"),
+                    callback = function()
+                        G_reader_settings:saveSetting("home_dir", realpath)
+                        UIManager:close(self.file_dialog)
+                    end
+                }
+            })
+        end
+        self.file_dialog = ButtonDialog:new{
+            buttons = buttons,
         }
         UIManager:show(self.file_dialog)
         return true

reader.lua

@@ -138,7 +138,8 @@ if ARGV[argidx] and ARGV[argidx] ~= "" then
     -- the filemanger will show the files in that path
     else
         local FileManager = require("apps/filemanager/filemanager")
-        FileManager:showFiles(ARGV[argidx])
+        local home_dir = G_reader_settings:readSetting("home_dir") or ARGV[argidx]
+        FileManager:showFiles(home_dir)
     end
     UIManager:run()
 elseif last_file then