Replicate seg fault (#191)

* Replicate seg fault
* Insert in one query
* Add check for statement and its member element presence
* Handle situation where the connection's db is not set

Co-authored-by: Matthew Johnston <warmwaffles@gmail.com>

Author: LostKobrakai

c_src/sqlite3_nif.c

@@ -470,6 +470,10 @@ exqlite_multi_step(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
         return make_error_tuple(env, "invalid_statement");
     }
 
+    if (!statement || !statement->statement) {
+        return make_error_tuple(env, "invalid_statement");
+    }
+
     if (!enif_get_int(env, argv[2], &chunk_size)) {
         return make_error_tuple(env, "invalid_chunk_size");
     }
@@ -627,6 +631,13 @@ exqlite_transaction_status(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
         return make_error_tuple(env, "invalid_connection");
     }
 
+    // If the connection times out, DbConnection disconnects the client
+    // and then re-opens a new connection. There is a condition where by
+    // the connection's database is not set but the calling elixir / erlang
+    // pass an incomplete reference.
+    if (!conn->db) {
+        return make_ok_tuple(env, make_atom(env, "error"));
+    }
     int autocommit = sqlite3_get_autocommit(conn->db);
     return make_ok_tuple(
       env,

test/exqlite/integration_test.exs

@@ -1,6 +1,8 @@
 defmodule Exqlite.IntegrationTest do
   use ExUnit.Case
 
+  import ExUnit.CaptureLog
+
   alias Exqlite.Connection
   alias Exqlite.Sqlite3
   alias Exqlite.Query
@@ -169,4 +171,40 @@ defmodule Exqlite.IntegrationTest do
 
     File.rm(path)
   end
+
+  test "exceeding timeout" do
+    path = Temp.path!()
+
+    {:ok, conn} =
+      DBConnection.start_link(Connection,
+        idle_interval: 5_000,
+        database: path,
+        journal_mode: :wal,
+        cache_size: -64_000,
+        temp_store: :memory
+      )
+
+    query = %Query{statement: "create table foo(id integer, val integer)"}
+    {:ok, _, _} = DBConnection.execute(conn, query, [])
+
+    values = for i <- 1..10000, do: "(#{i}, #{i})"
+
+    query = %Query{
+      statement: "insert into foo(id, val) values #{Enum.join(values, ",")}"
+    }
+
+    {:ok, _, _} = DBConnection.execute(conn, query, [])
+
+    # Don't want to muddy the test output
+    {_, log} =
+      with_log(fn ->
+        query = %Query{statement: "select * from foo"}
+        {:ok, _, _} = DBConnection.execute(conn, query, [], timeout: 1)
+      end)
+
+    # We want to ensure the timeout is logged
+    assert log =~ "timed out"
+
+    File.rm(path)
+  end
 end