Get the source code of the escript executable
by mistake I deleted the escript source code I wrote; as a last resort, I am trying to get the source (if at all possible) by decompiling an executable that I have deployed to the server.
In case that matters, it was compiled on Ubuntu 16.04 by running mix escript.build with no additional arguments.
I would appreciate it if someone could give me some pointers on how to do this or where to start!
thank
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You can get the compiled Erlang source of your files here. I do not think it is possible to return the original source of the elixir, as it is not at all in this document; only compiled Erlang bytecode. Decompiled Erlang code should be readable enough if you know some Erlang (if not, check out this quick Erlang ↔ Elixir course).
The escript executable starts with #! /usr/bin/env escript
, followed by some lines, and then the inline compiled files are present as a binary zip file. Open the escript file in an editor and delete everything until the line starts with PK
(start zip).
$ mix escript.build
$ head -c 59 m
#! /usr/bin/env escript
%%
%%! -escript main m_escript
PK
$ vim m # remove everything until `PK`
$ head -c2 m
PK
Now you can extract the contents of the file with unzip
and get all the compiled files .beam
:
$ unzip m -d extracted
Archive: m
inflating: extracted/m_escript.beam
inflating: extracted/Elixir.Version.Parser.DSL.beam
inflating: extracted/Elixir.Kernel.LexicalTracker.beam
inflating: extracted/Elixir.IO.ANSI.beam
inflating: extracted/Elixir.Inspect.NaiveDateTime.beam
inflating: extracted/Elixir.Protocol.beam
inflating: extracted/Elixir.Inspect.Any.beam
...
Finally, you can decompile the modules you want to use decompile-beam
:
$ decompile-beam extracted/Elixir.M.beam
-compile(no_auto_import).
-file("lib/m.ex", 1).
-module('Elixir.M').
-export(['__info__'/1, main/0, main/1]).
-spec '__info__'(attributes | compile | exports |
functions | macros | md5 | module |
native_addresses) -> atom() |
[{atom(), any()} |
{atom(), byte(), integer()}].
'__info__'(functions) -> [{main, 0}, {main, 1}];
'__info__'(macros) -> [];
'__info__'(info) ->
erlang:get_module_info('Elixir.M', info).
main() -> main([]).
main(args@1) -> 'Elixir.IO':inspect({args@1, args@1}).
This was the original source of the elixir:
$ cat lib/m.ex
defmodule M do
def main(args \\ []) do
IO.inspect {args, args}
end
end
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