functests: Check logs in lua code

It is otherwise impossible to determine which test failed sanitizer/valgrind
check. test/functional/helpers.lua module return was changed so that tests which
do not provide after_each function to get new check will automatically fail.

test/helpers.lua

@@ -0,0 +1,60 @@
+local assert = require('luassert')
+local lfs = require('lfs')
+
+local check_logs_useless_lines = {
+  ['Warning: noted but unhandled ioctl']=1,
+  ['could cause spurious value errors to appear']=2,
+  ['See README_MISSING_SYSCALL_OR_IOCTL for guidance']=3,
+}
+
+local eq = function(exp, act)
+  return assert.are.same(exp, act)
+end
+local neq = function(exp, act)
+  return assert.are_not.same(exp, act)
+end
+local ok = function(res)
+  return assert.is_true(res)
+end
+
+local function check_logs()
+  local log_dir = os.getenv('LOG_DIR')
+  local runtime_errors = 0
+  if log_dir and lfs.attributes(log_dir, 'mode') == 'directory' then
+    for tail in lfs.dir(log_dir) do
+      if tail:sub(1, 30) == 'valgrind-' or tail:find('san%.') then
+        local file = log_dir .. '/' .. tail
+        local fd = io.open(file)
+        local start_msg = ('='):rep(20) .. ' File ' .. file .. ' ' .. ('='):rep(20)
+        local lines = {}
+        local warning_line = 0
+        for line in fd:lines() do
+          local cur_warning_line = check_logs_useless_lines[line]
+          if cur_warning_line == warning_line + 1 then
+            warning_line = cur_warning_line
+          else
+            lines[#lines + 1] = line
+          end
+        end
+        fd:close()
+        os.remove(file)
+        if #lines > 0 then
+          -- local out = os.getenv('TRAVIS_CI_BUILD') and io.stdout or io.stderr
+          local out = io.stdout
+          out:write(start_msg .. '\n')
+          out:write('= ' .. table.concat(lines, '\n= ') .. '\n')
+          out:write(select(1, start_msg:gsub('.', '=')) .. '\n')
+          runtime_errors = runtime_errors + 1
+        end
+      end
+    end
+  end
+  assert(0 == runtime_errors)
+end
+
+return {
+  eq = eq,
+  neq = neq,
+  ok = ok,
+  check_logs = check_logs,
+}