Improved walkdir for LuaRT

local sys = require("sys")

local function walkdir(dir, ext, recurse)
    if type(dir) ~= "Directory" then
        dir = sys.Directory(dir)
    end
    if type(ext) == "string" then ext = {ext} end
    local entries = recurse or {}
    for entry in each(dir) do
        if type(entry) == "File" then
            if ext then
                for i = 1, #ext do
                    if entry.filename:match(".%" .. ext[i] .. "$") then
                        table.insert(entries, entry)
                        entries[entry.fullpath] = entry
                    end
                end
            else
                table.insert(entries, entry)
                entries[entry.fullpath] = entry
            end
        else
            entries = walkdir(entry, ext, entries)
        end
    end
    return entries
end

return walkdir