replace .. with table concat

Signed-off-by: vadim.zyarko <vadim.zyarko@sysdig.com>

userspace/engine/lua/rule_loader.lua

@@ -293,18 +293,18 @@ function split_lines(rules_content)
 end
 
 function get_orig_yaml_obj(rules_lines, row)
-   local ret = ""
-
     idx = row
+    local t = {}
     while (idx <= #rules_lines) do
-      ret = ret..rules_lines[idx].."\n"
+        t[#t + 1] = rules_lines[idx]
         idx = idx + 1
 
         if idx > #rules_lines or rules_lines[idx] == "" or string.sub(rules_lines[idx], 1, 1) == '-' then
             break
         end
     end
-
+    local ret = ""
+    ret = table.concat(t, "\n")
     return ret
 end
 
@@ -757,23 +757,26 @@ function build_exception_condition_string_multi_fields(eitem, exfields)
     local fields = eitem['fields']
     local comps = eitem['comps']
 
-   local icond = "("
+    local icond = {}
 
+    icond[#icond + 1] = "("
+
+    local lcount = 0
     for i, values in ipairs(eitem['values']) do
-
         if #fields ~= #values then
             return nil, "Exception item " .. eitem['name'] .. ": fields and values lists must have equal length"
         end
 
-      if icond ~= "(" then
-	 icond=icond.." or "
+        if lcount ~= 0 then
+            icond[#icond + 1] = " or "
         end
+        lcount = lcount + 1
 
-      icond=icond.."("
+        icond[#icond + 1] = "("
 
         for k = 1, #fields do
             if k > 1 then
-	    icond=icond.." and "
+                icond[#icond + 1] = " and "
             end
             local ival = values[k]
             local istr = ""
@@ -798,21 +801,22 @@ function build_exception_condition_string_multi_fields(eitem, exfields)
                 end
             end
 
-	 icond = icond..fields[k].." "..comps[k].." "..istr
+            icond[#icond + 1] = fields[k] .. " " .. comps[k] .. " " .. istr
             exfields[fields[k]] = true
         end
 
-      icond=icond..")"
+        icond[#icond + 1] = ")"
     end
 
-   icond = icond..")"
+    icond[#icond + 1] = ")"
 
     -- Don't return a trivially empty condition string
-   if icond == "()" then
-      icond = ""
+    local ret = table.concat(icond)
+    if ret == "()" then
+        return "", nil
     end
 
-   return icond, nil
+    return ret, nil
 
 end