Handle abnormal MySQL structure_load death gracefully (#723)

Author: greg-rychlewski

integration_test/myxql/storage_test.exs

@@ -121,6 +121,20 @@ defmodule Ecto.Integration.StorageTest do
     drop_database()
   end
 
+  test "structure load will fail on SQL errors" do
+    create_database()
+    File.mkdir_p!(tmp_path())
+    error_path = Path.join(tmp_path(), "error.sql")
+    File.write!(error_path, "SELECT 1; SELECKT 1; SELECT 2;")
+
+    {:error, message} =
+      Ecto.Adapters.MyXQL.structure_load(tmp_path(), [dump_path: error_path] ++ params())
+
+    assert message =~ ~r/ERROR.*SELECKT/
+  after
+    drop_database()
+  end
+
   test "storage status is up when database is created" do
     create_database()
     assert :up == Ecto.Adapters.MyXQL.storage_status(params())

lib/ecto/adapters/myxql.ex

@@ -588,12 +588,16 @@ defmodule Ecto.Adapters.MyXQL do
       args: args
     ]
 
+    # Trap exits in case mysql dies in the middle of execution so that we can surface the error
+    old_trap_exit = Process.flag(:trap_exit, true)
     port = Port.open({:spawn_executable, abs_cmd}, port_opts)
     Port.command(port, contents)
     # Use this as a signal to close the port since we cannot
     # send an exit command to mysql in batch mode
     Port.command(port, ";SELECT '__ECTO_EOF__';\n")
-    collect_output(port, "")
+    result = collect_output(port, "")
+    Process.flag(:trap_exit, old_trap_exit)
+    result
   end
 
   defp args_env(opts, opt_args) do
@@ -653,6 +657,9 @@ defmodule Ecto.Adapters.MyXQL do
           collect_output(port, acc)
         end
 
+      {:EXIT, ^port, _reason} ->
+        {acc, 1}
+
       {^port, {:exit_status, status}} ->
         {acc, status}
     end