bugfix: we should ignore match limit in DFA mode. (#1924)

lua_regex_match_limit takes effect globally for all regexes used in ngx.re
api. However, the match_limit field of pcre_extra block is not supported in
pcre_dfa_exec()(so does match_limit_recursion), because it is meaningless
in DFA matching. And pcre_dfa_exec() will return -18(PCRE_ERROR_DFA_UMLIMIT)
when the directive is used. Here we just ignore the directive in DFA mode.

Author: balusch

src/ngx_http_lua_regex.c

@@ -311,7 +311,10 @@ ngx_http_lua_ffi_compile_regex(const unsigned char *pat, size_t pat_len,
 
 #endif /* LUA_HAVE_PCRE_JIT */
 
-    if (sd && lmcf && lmcf->regex_match_limit > 0) {
+    if (sd
+        && lmcf && lmcf->regex_match_limit > 0
+        && !(flags & NGX_LUA_RE_MODE_DFA))
+    {
         sd->flags |= PCRE_EXTRA_MATCH_LIMIT;
         sd->match_limit = lmcf->regex_match_limit;
     }

t/120-re-find.t

@@ -917,3 +917,35 @@ to: 4
 pos: 5
 --- no_error_log
 [error]
+
+
+
+=== TEST 32: ignore match limit in DFA mode
+--- http_config
+    lua_regex_match_limit 1;
+--- config
+    location /re {
+        content_by_lua_block {
+            local s = "This is <something> <something else> <something further> no more"
+            local from, to, err = ngx.re.find(s, "<.*>", "d")
+            if from then
+                ngx.say("from: ", from)
+                ngx.say("to: ", to)
+                ngx.say("matched: ", string.sub(s, from, to))
+            else
+                if err then
+                    ngx.say("error: ", err)
+                    return
+                end
+                ngx.say("not matched!")
+            end
+        }
+    }
+--- request
+    GET /re
+--- response_body
+from: 9
+to: 56
+matched: <something> <something else> <something further>
+--- no_error_log
+[error]