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/*
* Copyright (c) 2015-2017, Intel Corporation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Intel Corporation nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/** \file
* \brief Rose construction from NGHolder for cases representing small literal
* sets.
*/
#include "ng_small_literal_set.h"
#include "grey.h"
#include "ng_holder.h"
#include "ng_util.h"
#include "rose/rose_build.h"
#include "util/compare.h"
#include "util/compile_context.h"
#include "util/container.h"
#include "util/graph_range.h"
#include "util/order_check.h"
#include "util/ue2string.h"
#include "ue2common.h"
#include <map>
#include <set>
#include <vector>
#include <boost/range/adaptor/map.hpp>
using namespace std;
using boost::adaptors::map_keys;
namespace ue2 {
/** \brief The maximum number of literals to accept per pattern. */
static const size_t MAX_LITERAL_SET_SIZE = 30;
/**
* \brief The maximum number of literals to accept per pattern where at least
* one is weak (has period < MIN_STRONG_PERIOD).
*/
static const size_t MAX_WEAK_LITERAL_SET_SIZE = 20;
/**
* \brief The minimum string period to consider a literal "strong" (and not
* apply the weak size limit).
*/
static const size_t MIN_STRONG_PERIOD = 3;
namespace {
struct sls_literal {
bool anchored;
bool eod;
ue2_literal s;
explicit sls_literal(bool a) : anchored(a), eod(false) {}
sls_literal append(char c, bool nocase) const {
sls_literal rv(anchored);
rv.s = s;
rv.s.push_back(ue2_literal::elem(c, nocase));
return rv;
}
};
static
bool operator<(const sls_literal &a, const sls_literal &b) {
ORDER_CHECK(anchored);
ORDER_CHECK(eod);
ORDER_CHECK(s);
return false;
}
} // namespace
static
bool checkLongMixedSensitivityLiterals(
const map<sls_literal, flat_set<ReportID>> &literals) {
const size_t len = MAX_MASK2_WIDTH;
for (const sls_literal &lit : literals | map_keys) {
if (mixed_sensitivity(lit.s) && lit.s.length() > len) {
return false;
}
}
return true;
}
static
bool findLiterals(const NGHolder &g,
map<sls_literal, flat_set<ReportID>> *literals) {
vector<NFAVertex> order = getTopoOrdering(g);
vector<set<sls_literal>> built(num_vertices(g));
vector<size_t> read_count(num_vertices(g));
for (auto it = order.rbegin(); it != order.rend(); ++it) {
NFAVertex v = *it;
set<sls_literal> &out = built[g[v].index];
read_count[g[v].index] = out_degree(v, g);
DEBUG_PRINTF("setting read_count to %zu for %zu\n",
read_count[g[v].index], g[v].index);
assert(out.empty());
if (v == g.start) {
out.insert(sls_literal(true));
continue;
} else if (v == g.startDs) {
out.insert(sls_literal(false));
continue;
}
bool eod = v == g.acceptEod;
bool accept = v == g.accept || v == g.acceptEod;
const CharReach &cr = g[v].char_reach;
for (auto u : inv_adjacent_vertices_range(v, g)) {
if (u == g.accept) {
continue;
}
if (u == g.start && edge(g.startDs, v, g).second) {
/* floating start states may have connections to start and
* startDs - don't create duplicate anchored literals */
DEBUG_PRINTF("skipping as floating\n");
continue;
}
set<sls_literal> &in = built[g[u].index];
DEBUG_PRINTF("getting from %zu (%zu reads to go)\n",
g[u].index, read_count[g[u].index]);
assert(!in.empty());
assert(read_count[g[u].index]);
for (const sls_literal &lit : in) {
if (accept) {
sls_literal accept_lit = lit; // copy
accept_lit.eod = eod;
insert(&(*literals)[accept_lit], g[u].reports);
continue;
}
for (size_t c = cr.find_first(); c != cr.npos;
c = cr.find_next(c)) {
bool nocase = ourisalpha(c) && cr.test(mytoupper(c))
&& cr.test(mytolower(c));
if (nocase && (char)c == mytolower(c)) {
continue; /* uppercase already handled us */
}
out.insert(lit.append((u8)c, nocase));
if (out.size() + literals->size() > MAX_LITERAL_SET_SIZE) {
DEBUG_PRINTF("too big %zu + %zu\n", out.size(),
literals->size());
return false;
}
}
}
read_count[g[u].index]--;
if (!read_count[g[u].index]) {
DEBUG_PRINTF("clearing %zu as finished reading\n", g[u].index);
in.clear();
}
}
}
return true;
}
static
size_t min_period(const map<sls_literal, flat_set<ReportID>> &literals) {
size_t rv = SIZE_MAX;
for (const sls_literal &lit : literals | map_keys) {
rv = min(rv, minStringPeriod(lit.s));
}
DEBUG_PRINTF("min period %zu\n", rv);
return rv;
}
// If this component is just a small set of literals and can be handled by
// Rose, feed it directly into rose.
bool handleSmallLiteralSets(RoseBuild &rose, const NGHolder &g,
const CompileContext &cc) {
if (!cc.grey.allowSmallLiteralSet) {
return false;
}
if (!isAcyclic(g)) {
/* literal sets would typically be acyclic... */
DEBUG_PRINTF("not acyclic\n");
return false;
}
if (!hasNarrowReachVertex(g, MAX_LITERAL_SET_SIZE * 2 + 1)) {
DEBUG_PRINTF("vertex with wide reach found\n");
return false;
}
DEBUG_PRINTF("looking for literals\n");
map<sls_literal, flat_set<ReportID>> literals;
if (!findLiterals(g, &literals)) {
DEBUG_PRINTF(":(\n");
return false;
}
assert(!literals.empty());
if (literals.size() > MAX_LITERAL_SET_SIZE) {
/* try a mask instead */
DEBUG_PRINTF("too many literals\n");
return false;
}
size_t period = min_period(literals);
if (period < MIN_STRONG_PERIOD &&
literals.size() > MAX_WEAK_LITERAL_SET_SIZE) {
DEBUG_PRINTF("too many literals with weak period\n");
return false;
}
if (!checkLongMixedSensitivityLiterals(literals)) {
DEBUG_PRINTF("long mixed\n");
return false;
}
DEBUG_PRINTF("adding %zu literals\n", literals.size());
for (const auto &m : literals) {
const sls_literal &lit = m.first;
const auto &reports = m.second;
rose.add(lit.anchored, lit.eod, lit.s, reports);
}
return true;
}
} // namespace ue2
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