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https://github.com/VectorCamp/vectorscan.git
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143 lines
4.4 KiB
C++
143 lines
4.4 KiB
C++
/*
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* Copyright (c) 2015, Intel Corporation
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Intel Corporation nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/** \file
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* \brief Rose mask construction from NGHolder.
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*/
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#include "ng_fixed_width.h"
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#include "grey.h"
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#include "ng_holder.h"
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#include "ng_util.h"
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#include "rose/rose_build.h"
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#include "util/container.h"
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#include "ue2common.h"
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#include <algorithm>
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#include <iterator>
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#include <set>
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using namespace std;
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namespace ue2 {
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static
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bool findMask(const NGHolder &g, vector<CharReach> *mask, bool *anchored,
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ue2::flat_set<ReportID> *reports) {
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DEBUG_PRINTF("looking for a mask pattern\n");
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set<NFAVertex> s_succ;
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insert(&s_succ, adjacent_vertices(g.start, g));
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set<NFAVertex> sds_succ;
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insert(&sds_succ, adjacent_vertices(g.startDs, g));
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*anchored = sds_succ.size() == 1; /* sds itself */
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bool floating = is_subset_of(s_succ, sds_succ);
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DEBUG_PRINTF("sds %zu s %zu%s%s\n", sds_succ.size(), s_succ.size(),
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*anchored ? " anchored" : "", floating ? " floating" : "");
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if (!*anchored && !floating) {
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DEBUG_PRINTF("semi-anchored\n");
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return false;
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}
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set<NFAVertex> &succs = *anchored ? s_succ : sds_succ;
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succs.erase(g.startDs);
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if (succs.size() != 1) {
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DEBUG_PRINTF("branchy root\n");
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return false;
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}
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NFAVertex u = *anchored ? g.start : g.startDs;
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NFAVertex v = *succs.begin();
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while (true) {
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DEBUG_PRINTF("validating vertex %u\n", g[v].index);
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assert(v != g.acceptEod);
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// If we've reached an accept, we MAY have found a valid Rose pattern
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if (v == g.accept) {
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DEBUG_PRINTF("accept\n");
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insert(reports, g[u].reports);
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return true;
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}
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mask->push_back(g[v].char_reach);
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if (out_degree(v, g) != 1) {
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DEBUG_PRINTF("out_degree != 1\n");
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return false; /* not a chain */
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}
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u = v;
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v = *adjacent_vertices(v, g).first;
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if (in_degree(v, g) != 1) {
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DEBUG_PRINTF("blargh\n"); /* picks up cases where there is no path
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* to case accept (large cycles),
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* ensures term */
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return false;
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}
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}
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}
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bool handleFixedWidth(RoseBuild &rose, const NGHolder &g, const Grey &grey) {
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if (!grey.roseMasks) {
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return false;
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}
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if (in_degree(g.acceptEod,g) != 1) {
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DEBUG_PRINTF("EOD anchoring not supported\n");
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return false;
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}
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ue2::flat_set<ReportID> reports;
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bool anchored = false;
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vector<CharReach> mask;
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if (!findMask(g, &mask, &anchored, &reports)) {
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return false;
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}
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DEBUG_PRINTF("%smasky masky\n", anchored ? "anchored " : "");
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assert(!mask.empty());
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assert(!reports.empty());
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if (rose.add(anchored, mask, reports)) {
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DEBUG_PRINTF("added as rose mask\n");
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return true;
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} else {
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DEBUG_PRINTF("failed to add masky\n");
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return false;
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}
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}
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} // namespace ue2
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