Compatability of exqlite/Sqlite3, Escript and WSL2?

Questions / Help
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1

Hi,
I developed a small program that uses ecto + ecto_sqlite3 and as a nested dependency exqlite.
The program works fine when I execute it with mix run, but when I try to compile it to an escript fails to run.

It crashes right at the startup with the following warning + error messages:

13:22:19.172 [warn]  The on_load function for module Elixir.Exqlite.Sqlite3NIF returned:
{:function_clause,
 [
   {:filename, :join, [{:error, :bad_name}, 'sqlite3_nif'],
    [file: 'filename.erl', line: 454]},
   {Exqlite.Sqlite3NIF, :load_nifs, 0,
    [file: 'lib/exqlite/sqlite3_nif.ex', line: 14]},
   {:code_server, :"-handle_on_load/5-fun-0-", 1,
    [file: 'code_server.erl', ...]}
 ]}


13:22:19.211 [debug] Websocket connection up on worker #PID<0.231.0>

13:22:19.169 [error] Process #PID<0.296.0> raised an exception
** (FunctionClauseError) no function clause matching in :filename.join/2
    (stdlib 3.15.1) filename.erl:454: :filename.join({:error, :bad_name}, 'sqlite3_nif')
    (exqlite 0.6.1) lib/exqlite/sqlite3_nif.ex:14: Exqlite.Sqlite3NIF.load_nifs/0
    (kernel 8.0.1) code_server.erl:1317: anonymous fn/1 in :code_server.handle_on_load/5

13:22:19.204 [error] GenServer #PID<0.286.0> terminating
** (RuntimeError) connect raised UndefinedFunctionError exception. The exception details are hidden, as they may contain sensitive data such as database credentials. You may set :show_sensitive_data_on_connection_error to true when starting your connection if you wish to see all of the details
    (exqlite 0.6.1) Exqlite.Sqlite3NIF.open/1
    (exqlite 0.6.1) lib/exqlite/connection.ex:402: Exqlite.Connection.do_connect/2
    (db_connection 2.4.0) lib/db_connection/connection.ex:82: DBConnection.Connection.connect/2
    (connection 1.1.0) lib/connection.ex:622: Connection.enter_connect/5
    (stdlib 3.15.1) proc_lib.erl:226: :proc_lib.init_p_do_apply/3
Last message: nil
State: Exqlite.Connection

It ‘may’ be relate to a warning that is logged during compilation of the exqlite dependency:

In file included from /usr/include/string.h:494:0,
                 from sqlite3/sqlite3.c:14232:
In function ‘memcpy’,
    inlined from ‘rbuGetUpdateStmt.constprop’ at sqlite3/sqlite3.c:201606:5,
    inlined from ‘rbuStep’ at sqlite3/sqlite3.c:202418:7,
    inlined from ‘sqlite3rbu_step’ at sqlite3/sqlite3.c:202651:24:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:34:10: warning: ‘__builtin_memcpy’: specified size between 18446744071562067968 and 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=]
   return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest));
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Has anyone ever encountered similar problems with exqlite?

Since it works fine when it’s executed with mix run, might it be related to some incompatibility related to WSL2? Or could it be another reason entirely?

Thanks in advance.

2

Hey,

The root error is:

    (stdlib 3.15.1) filename.erl:454: :filename.join({:error, :bad_name}, 'sqlite3_nif')
    (exqlite 0.6.1) lib/exqlite/sqlite3_nif.ex:14: Exqlite.Sqlite3NIF.load_nifs/0

Which comes from the line of code where we load our NIF:

  def load_nifs() do
    path = :filename.join(:code.priv_dir(:exqlite), 'sqlite3_nif')
    :erlang.load_nif(path, 0)
  end

It looks like this is because the priv/ directory is not supproted in escript.

It looks like NIFs in general cannot work in escript. Bummer.

2 Likes
3

Thank you very much for the response and the detailed explanation :slight_smile:

It looks like NIFs in general cannot work in escript. Bummer.

That is indeed a bummer. Escript seemed like a good idea to deploy a small elixir program.

4

I haven’t used this, but this may do what you want:

I think this is the OTP issue for enabling the functionality natively, but I wouldn’t count on it being implemented anytime soon: