Merge pull request #555 from Tieske/fix/luajit

fix LuaJIT segfault due to ffi reloading

busted/modules/configuration_loader.lua

@@ -7,7 +7,7 @@ return function()
       return nil, '.busted file does not return a table.'
     end
 
-    local defaults = defaults or {}
+    defaults = defaults or {}
     local run = config.run or defaults.run
 
     if run and run ~= '' then

busted/runner.lua

@@ -133,6 +133,25 @@ return function(options)
     arguments = cliArgs.Xoutput,
   })
 
+  -- Pre-load the LuaJIT 'ffi' module if applicable
+  local isJit = (tostring(assert):match('builtin') ~= nil)
+  if isJit then
+    -- pre-load the ffi module, such that it becomes part of the environment
+    -- and Busted will not try to GC and reload it. The ffi is not suited
+    -- for that and will occasionally segfault if done so.
+    local ffi = require "ffi"
+
+    -- Now patch ffi.cdef to only be called once with each definition, as it
+    -- will error on re-registering.
+    local old_cdef = ffi.cdef
+    local exists = {}
+    ffi.cdef = function(def)
+      if exists[def] then return end
+      exists[def] = true
+      return old_cdef(def)
+    end
+  end
+
   -- Set up helper script
   if cliArgs.helper and cliArgs.helper ~= '' then
     helperLoader(busted, cliArgs.helper, {