[Tarantool-patches] [PATCH 2/2] box: raise on raw modifications of box.cfg values

[Olga Arkhangelskaia <arkholga@tarantool.org>]

Prior this patch there was a possibility to change values throw
the raw table modification, like box.cfg.log_level = , or
box.cfg["log_level"] = . Now we store cfg values in separate table,
how ever the behaviour stays the same.

Closes #2867
---
 src/box/lua/load_cfg.lua  | 18 +++++++++++--
 test/box-tap/cfg.test.lua | 14 +++++++++-
 test/box/cfg.result       | 55 +++++++++++++++++++++++++++++++++++++++
 test/box/cfg.test.lua     |  3 +++
 4 files changed, 87 insertions(+), 3 deletions(-)

diff --git a/src/box/lua/load_cfg.lua b/src/box/lua/load_cfg.lua
index 85617c8f0..602bf92c5 100644
--- a/src/box/lua/load_cfg.lua
+++ b/src/box/lua/load_cfg.lua
@@ -533,13 +533,27 @@ local function load_cfg(cfg)
     end
     setmetatable(box, nil)
     box_configured = nil
-    box.cfg = setmetatable(cfg,
+    box.cfg = {}
+    local actual = cfg
+    box.cfg = setmetatable({},
         {
             __newindex = function(table, index)
                 error('Attempt to modify a read-only table')
             end,
             __call = locked(reload_cfg),
-        })
+            __index = function (self, k)
+                return actual[k]
+            end,
+            __serialize = function() return actual end,
+
+            __pairs = function(self)
+                local function iter(actual, k)
+                    local v
+                    return next(actual, k)
+                end
+                return iter, actual, nil
+            end
+         })
     private.cfg_load()
     for key, fun in pairs(dynamic_cfg) do
         local val = cfg[key]
diff --git a/test/box-tap/cfg.test.lua b/test/box-tap/cfg.test.lua
index b61073438..b76f28893 100755
--- a/test/box-tap/cfg.test.lua
+++ b/test/box-tap/cfg.test.lua
@@ -6,7 +6,7 @@ local socket = require('socket')
 local fio = require('fio')
 local uuid = require('uuid')
 local msgpack = require('msgpack')
-test:plan(104)
+test:plan(106)
 
 --------------------------------------------------------------------------------
 -- Invalid values
@@ -592,6 +592,18 @@ box.cfg{read_only=true}
 ]]
 test:is(run_script(code), PANIC, "panic on bootstrapping a read-only instance as master")
 
+--
+-- gf-2867 raise on raw modifications of box.cfg values
+--
+code = [[
+box.cfg{}
+box.cfg.read_only = true
+]]
+test:is(run_script(code), PANIC, "attempt to modify a read-only table")
 
+code = [[
+box.cfg["read_only"] = true
+]]
+test:is(run_script(code), PANIC, "attempt to modify a read-only table")
 test:check()
 os.exit(0)
diff --git a/test/box/cfg.result b/test/box/cfg.result
index 5370bb870..9031e1480 100644
--- a/test/box/cfg.result
+++ b/test/box/cfg.result
@@ -236,6 +236,61 @@ box.cfg{replication = {}}
  | ---
  | ...
 
+cfg = {}
+ | ---
+ | ...
+for k, v in pairs(box.cfg) do table.insert(cfg, k) end
+ | ---
+ | ...
+cfg
+ | ---
+ | - - pid_file
+ |   - checkpoint_count
+ |   - feedback_host
+ |   - readahead
+ |   - log_level
+ |   - checkpoint_interval
+ |   - vinyl_page_size
+ |   - coredump
+ |   - replication_sync_lag
+ |   - replication_timeout
+ |   - wal_dir_rescan_delay
+ |   - vinyl_memory
+ |   - replication_skip_conflict
+ |   - strip_core
+ |   - feedback_enabled
+ |   - wal_max_size
+ |   - too_long_threshold
+ |   - memtx_memory
+ |   - log
+ |   - background
+ |   - vinyl_dir
+ |   - vinyl_cache
+ |   - vinyl_read_threads
+ |   - vinyl_bloom_fpr
+ |   - vinyl_timeout
+ |   - net_msg_max
+ |   - listen
+ |   - force_recovery
+ |   - vinyl_max_tuple_size
+ |   - vinyl_run_count_per_level
+ |   - hot_standby
+ |   - log_format
+ |   - memtx_max_tuple_size
+ |   - memtx_min_tuple_size
+ |   - feedback_interval
+ |   - vinyl_write_threads
+ |   - wal_mode
+ |   - worker_pool_threads
+ |   - vinyl_run_size_ratio
+ |   - read_only
+ |   - memtx_dir
+ |   - wal_dir
+ |   - slab_alloc_factor
+ |   - checkpoint_wal_threshold
+ |   - replication_connect_timeout
+ |   - replication_sync_timeout
+ | ...
 --------------------------------------------------------------------------------
 -- Test of hierarchical cfg type check
 --------------------------------------------------------------------------------
diff --git a/test/box/cfg.test.lua b/test/box/cfg.test.lua
index 56ccb6767..275737e7a 100644
--- a/test/box/cfg.test.lua
+++ b/test/box/cfg.test.lua
@@ -19,6 +19,9 @@ box.cfg{coredump = 'true'}
 box.cfg{replication = {}}
 box.cfg{replication = {}}
 
+cfg = {}
+for k, v in pairs(box.cfg) do table.insert(cfg, k) end
+cfg
 --------------------------------------------------------------------------------
 -- Test of hierarchical cfg type check
 --------------------------------------------------------------------------------
-- 
2.20.1 (Apple Git-117)