1 | /* |
2 | * Copyright (c) 2015-2017, Intel Corporation |
3 | * |
4 | * Redistribution and use in source and binary forms, with or without |
5 | * modification, are permitted provided that the following conditions are met: |
6 | * |
7 | * * Redistributions of source code must retain the above copyright notice, |
8 | * this list of conditions and the following disclaimer. |
9 | * * Redistributions in binary form must reproduce the above copyright |
10 | * notice, this list of conditions and the following disclaimer in the |
11 | * documentation and/or other materials provided with the distribution. |
12 | * * Neither the name of Intel Corporation nor the names of its contributors |
13 | * may be used to endorse or promote products derived from this software |
14 | * without specific prior written permission. |
15 | * |
16 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
17 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
18 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
19 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
20 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
21 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
22 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
23 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
24 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
25 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
26 | * POSSIBILITY OF SUCH DAMAGE. |
27 | */ |
28 | |
29 | /** \file |
30 | * \brief Rose mask construction from NGHolder. |
31 | */ |
32 | #include "ng_fixed_width.h" |
33 | |
34 | #include "grey.h" |
35 | #include "ng_holder.h" |
36 | #include "ng_util.h" |
37 | #include "rose/rose_build.h" |
38 | #include "util/container.h" |
39 | #include "ue2common.h" |
40 | |
41 | #include <algorithm> |
42 | #include <iterator> |
43 | #include <set> |
44 | |
45 | using namespace std; |
46 | |
47 | namespace ue2 { |
48 | |
49 | static |
50 | bool findMask(const NGHolder &g, vector<CharReach> *mask, bool *anchored, |
51 | flat_set<ReportID> *reports) { |
52 | DEBUG_PRINTF("looking for a mask pattern\n" ); |
53 | set<NFAVertex> s_succ; |
54 | insert(&s_succ, adjacent_vertices(g.start, g)); |
55 | |
56 | set<NFAVertex> sds_succ; |
57 | insert(&sds_succ, adjacent_vertices(g.startDs, g)); |
58 | |
59 | *anchored = sds_succ.size() == 1; /* sds itself */ |
60 | bool floating = is_subset_of(s_succ, sds_succ); |
61 | |
62 | DEBUG_PRINTF("sds %zu s %zu%s%s\n" , sds_succ.size(), s_succ.size(), |
63 | *anchored ? " anchored" : "" , floating ? " floating" : "" ); |
64 | if (!*anchored && !floating) { |
65 | DEBUG_PRINTF("semi-anchored\n" ); |
66 | return false; |
67 | } |
68 | |
69 | set<NFAVertex> &succs = *anchored ? s_succ : sds_succ; |
70 | succs.erase(g.startDs); |
71 | if (succs.size() != 1) { |
72 | DEBUG_PRINTF("branchy root\n" ); |
73 | return false; |
74 | } |
75 | |
76 | NFAVertex u = *anchored ? g.start : g.startDs; |
77 | NFAVertex v = *succs.begin(); |
78 | |
79 | while (true) { |
80 | DEBUG_PRINTF("validating vertex %zu\n" , g[v].index); |
81 | |
82 | assert(v != g.acceptEod); |
83 | |
84 | // If we've reached an accept, we MAY have found a valid Rose pattern |
85 | if (v == g.accept) { |
86 | DEBUG_PRINTF("accept\n" ); |
87 | insert(reports, g[u].reports); |
88 | return true; |
89 | } |
90 | |
91 | mask->push_back(g[v].char_reach); |
92 | |
93 | if (out_degree(v, g) != 1) { |
94 | DEBUG_PRINTF("out_degree != 1\n" ); |
95 | return false; /* not a chain */ |
96 | } |
97 | |
98 | u = v; |
99 | v = *adjacent_vertices(v, g).first; |
100 | |
101 | if (in_degree(v, g) != 1) { |
102 | DEBUG_PRINTF("blargh\n" ); /* picks up cases where there is no path |
103 | * to case accept (large cycles), |
104 | * ensures term */ |
105 | return false; |
106 | } |
107 | } |
108 | } |
109 | |
110 | bool handleFixedWidth(RoseBuild &rose, const NGHolder &g, const Grey &grey) { |
111 | if (!grey.roseMasks) { |
112 | return false; |
113 | } |
114 | |
115 | if (in_degree(g.acceptEod,g) != 1) { |
116 | DEBUG_PRINTF("EOD anchoring not supported\n" ); |
117 | return false; |
118 | } |
119 | |
120 | flat_set<ReportID> reports; |
121 | bool anchored = false; |
122 | vector<CharReach> mask; |
123 | |
124 | if (!findMask(g, &mask, &anchored, &reports)) { |
125 | return false; |
126 | } |
127 | |
128 | DEBUG_PRINTF("%smasky masky\n" , anchored ? "anchored " : "" ); |
129 | |
130 | assert(!mask.empty()); |
131 | assert(!reports.empty()); |
132 | |
133 | if (rose.add(anchored, mask, reports)) { |
134 | DEBUG_PRINTF("added as rose mask\n" ); |
135 | return true; |
136 | } else { |
137 | DEBUG_PRINTF("failed to add masky\n" ); |
138 | return false; |
139 | } |
140 | } |
141 | |
142 | } // namespace ue2 |
143 | |