box: drop 'execute' field from uninitialized box

Prior to this patch, it was possible to call box.execute() before box
was initialized, i.e. before calling box.cfg(). This, however, caused
box.cfg() to be called automatically, which could be problematic as some
parameters could not be changed after box.cfg() was called. After this
patch, box.execute() will only be available when the box has been
initialized.

Closes tarantool#4726

@TarantoolBot document
Title: box.execute() now available only after initialization of box

Previously, it was possible to call box.execute() before the box was
configured, in which case the box was configured automatically, which
could lead to problems with box parameters. Now box.execute() can only
be called after the box has been properly configured.

It is also forbidden to set language to SQL in a console with an
unconfigured box.

changelogs/unreleased/gh-4726-execute-field-in-box.md

@@ -0,0 +1,4 @@
+## bugfix/box
+
+* **[Breaking change]** Now the "execute" field is not available until box is
+ configured (gh-4726).

src/box/lua/console.lua

@@ -278,6 +278,9 @@ local function set_language(storage, value)
  local msg = 'Invalid language "%s", supported languages: lua and sql.'
  return error(msg:format(value))
  end
+ if value == 'sql' and rawget(box, 'execute') == nil then
+ return error("Unable to set language to 'sql' with unconfigured box")
+ end
  storage.language = value
  return true
 end

src/box/lua/load_cfg.lua

@@ -990,43 +990,6 @@ local function load_cfg(cfg)
 end
 box.cfg = locked(load_cfg)
 
---
--- This makes possible do box.execute without calling box.cfg
--- manually. The load_cfg() call overwrites box.execute, see
--- <box_configured> variable.
---
--- box.execute is <box_load_and_execute> when box is not loaded,
--- <lbox_execute> otherwise. <box_load_and_execute> loads box and
--- calls <lbox_execute>.
---
-local box_load_and_execute
-box_load_and_execute = function(...)
- -- Configure box if it is not configured, no-op otherwise (not
- -- a reconfiguration).
- --
- -- We should check whether box is configured, because a user
- -- may save <box_load_and_execute> function before box loading
- -- and call it afterwards.
- if not box_is_configured then
- locked(function()
- -- Re-check, because after releasing of the lock the
- -- box state may be changed. We should call load_cfg()
- -- only once.
- if not box_is_configured then
- load_cfg()
- end
- end)()
- end
-
- -- At this point box should be configured and box.execute()
- -- function should be replaced with lbox_execute().
- assert(type(box.cfg) ~= 'function')
- assert(box.execute ~= box_load_and_execute)
-
- return box.execute(...)
-end
-box.execute = box_load_and_execute
-
 --
 -- Parse TT_* environment variable that corresponds to given
 -- option.

test/box-luatest/gh_4726_box_execute_before_cfg_test.lua

@@ -0,0 +1,15 @@
+local t = require('luatest')
+local g = t.group()
+
+g.test_box_execute_before_box_cfg = function()
+ t.assert_equals(rawget(box, 'execute'), nil)
+end
+
+g.test_sql_language_in_unconfigured_console = function()
+ local res = [[
+---
+- error: Unable to set language to 'sql' with unconfigured box
+...
+]]
+ t.assert_equals(require('console').eval('\\s l sql'), res)
+end