The BEAM includes tooling to do part of this, :beam_disasm.

{:ok, {{_, 200, _}, headers, body_charlist}} = :httpc.request('https://github.com/granados12/decompile/blob/main/holiday_role_data4.beam?raw=true')

body = :binary.list_to_bin(body_charlist)

:beam_disasm.file(body)

This produces output like (you’ll want to make sure to use IO.inspect(limit: :infinity) to prevent cutting off terms):

{:beam_file, :holiday_role_data,
 [
   {:all_son, 0, 12},
   {:all_son2, 0, 14},
   {:bid_son, 1, 21},
   {:get, 1, 853},
   {:get_const, 1, 1259},
   {:get_open, 1, 59},
   {:list_open_son, 1, 4},
   {:list_open_total, 0, 2},
   {:list_son, 1, 16},
   {:list_total, 0, 10},
   {:main_ico, 1, 1257},
   {:module_info, 0, 1265},
   {:module_info, 1, 1267},
   {:open_ico, 1, 1255}
 ],
 [
   lager_records: [
     condition: [:label, :op, :val, :msg],
     holiday: [:camp_id, :total_id, :bid, :tbid, :cli_type, :cli_type_name, :start_time, :end_time,
      :condition, :type, :title, :title2, :main_ico, :ico, :type_ico, :top_banner, :rule_str,
      :time_str, :bottom_alert, :sort_val, :reward_title, :aim_title, :reward, :item_effect,
      :mail_subject, :mail_content, :cli_reward, :panel_type, :open_day, :open_day_min,
      :open_day_max, :merge_day, :process_show_reward, :platform_id, :platform_exclude_id,
      :hide_srv_ids, :channel_ban],
     holiday_total: [:id, :name, :icon_id, :start_time, :end_time, :status, :open_day, :merge_day,
      :is_show, :type]
   ],
   vsn: [320956466309601905319104183717896391347]
 ],
 [
   options: [
     :error_summary,
     {:hipe, [:o3]},
     :debug_info,
     {:i, 'inc'},
     {:outdir, 'ebin'},
     {:parse_transform, :lager_transform},
     {:d, :disable_auth},
     {:d, :enable_gm_cmd},
     {:d, :debug},
     {:d, :data_debug}
   ],
   version: '7.0.4',
   source: '/elora/server/src/data/holiday_role_data.erl'
 ],
 [
   {:function, :list_open_total, 0, 2,
    [
      {:label, 1},
      {:line, 1},
      {:func_info, {:atom, :holiday_role_data}, {:atom, :list_open_total}, 0},
      {:label, 2},
      {:allocate_zero, 1, 0},
      {:move, {:literal, "HĐ Gộp SV"}, {:x, 0}},
      {:line, 2},
      {:call_ext, 1, {:extfunc, :lang, :get, 1}},
      {:move, {:x, 0}, {:y, 0}},
      {:move, {:literal, "HĐ Mở SV"}, {:x, 0}},
      {:line, 3},
      {:call_ext, 1, {:extfunc, :lang, :get, 1}},
      {:test_heap, 28, 1},
      {:put_tuple, 11, {:x, 1}},
      {:put, {:atom, :holiday_total}},
      {:put, {:integer, 103}},
      {:put, {:x, 0}},
      {:put, {:integer, 0}},
      {:put, {:literal, {:open_day, 1}}},
      {:put, {:literal, {:open_day, 56, 86399}}},
      {:put, {:integer, 1}},
      {:put, {:integer, 0}},
      {:put, {:integer, 0}},
      {:put, {:integer, 1}},
      {:put, {:integer, 1}},
      {:put_list, {:x, 1}, nil, {:x, 1}},
      {:put_tuple, 11, {:x, 2}},
      {:put, {:atom, :holiday_total}},
      {:put, {:integer, 104}},
      {:put, {:y, 0}},
      {:put, {:integer, 0}},
      {:put, {:literal, {:merge_day, 1}}},

As for editing this BEAM file, that’s not something that’s normally done - BEAM files are written by the compiler so if you want to change them you change the Erlang etc code and recompile. According to the metadata in that file, that’s in src/data/holiday_role_data.erl.

I know nothing about Beam file format, but maybe you can get some inspiration in how to approach the problem inspect this repo GitHub - michalmuskala/decompile · GitHub

It should output an .erl file in the current working directory.

:\testproject\myproject>mix run tt.exs > holiday_role_data.erl
warning: function deps/0 is unused
  mix.exs:23

** (CompileError) mix.exs:10: undefined function deps/1 

How is your mix.exs file like? The deps({:decompilerl, github: "niahoo/decompilerl"}) is strange.

Generally you will have a deps: deps(), call in the project/0 function of the mix.exs file and dependencies defined like this:

  defp deps do
    [
      # ...
      {:decompilerl, github: "niahoo/decompilerl"}
    ]
  end

But you do not need the dependency in your project, you can just install the tool:

mix archive.install github niahoo/decompilerl
# or
mix archive.install github michalmuskala/decompile