From: Justin Viiret <justin.viiret@intel.com>
Date: Thu, 22 Jun 2017 06:51:35 +0000 (+1000)
Subject: clear_deeper_reports: clear dfa if dead
X-Git-Tag: v4.6.0^2~165
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3d4d39b8a98acdedae2e721ae35ce90a19e0e976;p=thirdparty%2Fvectorscan.git

clear_deeper_reports: clear dfa if dead

If we remove all the reports from the DFA because they're too deep, then
clear the DFA without depending on Hopcroft minimisation.
---

diff --git a/src/nfa/mcclellancompile_util.cpp b/src/nfa/mcclellancompile_util.cpp
index 17e022fe..8bb258d3 100644
--- a/src/nfa/mcclellancompile_util.cpp
+++ b/src/nfa/mcclellancompile_util.cpp
@@ -187,7 +187,22 @@ bool clear_deeper_reports(raw_dfa &raw, u32 max_offset) {
         }
     }
 
-    return changed;
+    if (!changed) {
+        return false;
+    }
+
+    // We may have cleared all reports from the DFA, in which case it should
+    // become empty.
+    if (all_of_in(raw.states, [](const dstate &ds) {
+            return ds.reports.empty() && ds.reports_eod.empty();
+        })) {
+        DEBUG_PRINTF("no reports left at all, dfa is dead\n");
+        raw.states.clear();
+        raw.start_anchored = DEAD_STATE;
+        raw.start_floating = DEAD_STATE;
+    }
+
+    return true;
 }
 
 set<ReportID> all_reports(const raw_dfa &rdfa) {