1 //===-- SpecialCaseList.cpp - special case list for sanitizers ------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This is a utility class for instrumentation passes (like AddressSanitizer
10 // or ThreadSanitizer) to avoid instrumenting some functions or global
11 // variables, or to instrument some functions or global variables in a specific
12 // way, based on a user-supplied list.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "llvm/Support/SpecialCaseList.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/StringExtras.h"
19 #include "llvm/Support/MemoryBuffer.h"
20 #include "llvm/Support/Regex.h"
21 #include "llvm/Support/VirtualFileSystem.h"
22 #include <string>
23 #include <system_error>
24 #include <utility>
25 
26 #include <stdio.h>
27 namespace llvm {
28 
29 bool SpecialCaseList::Matcher::insert(std::string Regexp,
30                                       unsigned LineNumber,
31                                       std::string &REError) {
32   if (Regexp.empty()) {
33     REError = "Supplied regexp was blank";
34     return false;
35   }
36 
37   if (Regex::isLiteralERE(Regexp)) {
38     Strings[Regexp] = LineNumber;
39     return true;
40   }
41   Trigrams.insert(Regexp);
42 
43   // Replace * with .*
44   for (size_t pos = 0; (pos = Regexp.find('*', pos)) != std::string::npos;
45        pos += strlen(".*")) {
46     Regexp.replace(pos, strlen("*"), ".*");
47   }
48 
49   Regexp = (Twine("^(") + StringRef(Regexp) + ")$").str();
50 
51   // Check that the regexp is valid.
52   Regex CheckRE(Regexp);
53   if (!CheckRE.isValid(REError))
54     return false;
55 
56   RegExes.emplace_back(
57       std::make_pair(std::make_unique<Regex>(std::move(CheckRE)), LineNumber));
58   return true;
59 }
60 
61 unsigned SpecialCaseList::Matcher::match(StringRef Query) const {
62   auto It = Strings.find(Query);
63   if (It != Strings.end())
64     return It->second;
65   if (Trigrams.isDefinitelyOut(Query))
66     return false;
67   for (auto& RegExKV : RegExes)
68     if (RegExKV.first->match(Query))
69       return RegExKV.second;
70   return 0;
71 }
72 
73 std::unique_ptr<SpecialCaseList>
74 SpecialCaseList::create(const std::vector<std::string> &Paths,
75                         llvm::vfs::FileSystem &FS, std::string &Error) {
76   std::unique_ptr<SpecialCaseList> SCL(new SpecialCaseList());
77   if (SCL->createInternal(Paths, FS, Error))
78     return SCL;
79   return nullptr;
80 }
81 
82 std::unique_ptr<SpecialCaseList> SpecialCaseList::create(const MemoryBuffer *MB,
83                                                          std::string &Error) {
84   std::unique_ptr<SpecialCaseList> SCL(new SpecialCaseList());
85   if (SCL->createInternal(MB, Error))
86     return SCL;
87   return nullptr;
88 }
89 
90 std::unique_ptr<SpecialCaseList>
91 SpecialCaseList::createOrDie(const std::vector<std::string> &Paths,
92                              llvm::vfs::FileSystem &FS) {
93   std::string Error;
94   if (auto SCL = create(Paths, FS, Error))
95     return SCL;
96   report_fatal_error(Error);
97 }
98 
99 bool SpecialCaseList::createInternal(const std::vector<std::string> &Paths,
100                                      vfs::FileSystem &VFS, std::string &Error) {
101   StringMap<size_t> Sections;
102   for (const auto &Path : Paths) {
103     ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
104         VFS.getBufferForFile(Path);
105     if (std::error_code EC = FileOrErr.getError()) {
106       Error = (Twine("can't open file '") + Path + "': " + EC.message()).str();
107       return false;
108     }
109     std::string ParseError;
110     if (!parse(FileOrErr.get().get(), Sections, ParseError)) {
111       Error = (Twine("error parsing file '") + Path + "': " + ParseError).str();
112       return false;
113     }
114   }
115   return true;
116 }
117 
118 bool SpecialCaseList::createInternal(const MemoryBuffer *MB,
119                                      std::string &Error) {
120   StringMap<size_t> Sections;
121   if (!parse(MB, Sections, Error))
122     return false;
123   return true;
124 }
125 
126 bool SpecialCaseList::parse(const MemoryBuffer *MB,
127                             StringMap<size_t> &SectionsMap,
128                             std::string &Error) {
129   // Iterate through each line in the exclusion list file.
130   SmallVector<StringRef, 16> Lines;
131   MB->getBuffer().split(Lines, '\n');
132 
133   unsigned LineNo = 1;
134   StringRef Section = "*";
135 
136   for (auto I = Lines.begin(), E = Lines.end(); I != E; ++I, ++LineNo) {
137     *I = I->trim();
138     // Ignore empty lines and lines starting with "#"
139     if (I->empty() || I->startswith("#"))
140       continue;
141 
142     // Save section names
143     if (I->startswith("[")) {
144       if (!I->endswith("]")) {
145         Error = (Twine("malformed section header on line ") + Twine(LineNo) +
146                  ": " + *I).str();
147         return false;
148       }
149 
150       Section = I->slice(1, I->size() - 1);
151 
152       std::string REError;
153       Regex CheckRE(Section);
154       if (!CheckRE.isValid(REError)) {
155         Error =
156             (Twine("malformed regex for section ") + Section + ": '" + REError)
157                 .str();
158         return false;
159       }
160 
161       continue;
162     }
163 
164     // Get our prefix and unparsed regexp.
165     std::pair<StringRef, StringRef> SplitLine = I->split(":");
166     StringRef Prefix = SplitLine.first;
167     if (SplitLine.second.empty()) {
168       // Missing ':' in the line.
169       Error = (Twine("malformed line ") + Twine(LineNo) + ": '" +
170                SplitLine.first + "'").str();
171       return false;
172     }
173 
174     std::pair<StringRef, StringRef> SplitRegexp = SplitLine.second.split("=");
175     std::string Regexp = std::string(SplitRegexp.first);
176     StringRef Category = SplitRegexp.second;
177 
178     // Create this section if it has not been seen before.
179     if (SectionsMap.find(Section) == SectionsMap.end()) {
180       std::unique_ptr<Matcher> M = std::make_unique<Matcher>();
181       std::string REError;
182       if (!M->insert(std::string(Section), LineNo, REError)) {
183         Error = (Twine("malformed section ") + Section + ": '" + REError).str();
184         return false;
185       }
186 
187       SectionsMap[Section] = Sections.size();
188       Sections.emplace_back(std::move(M));
189     }
190 
191     auto &Entry = Sections[SectionsMap[Section]].Entries[Prefix][Category];
192     std::string REError;
193     if (!Entry.insert(std::move(Regexp), LineNo, REError)) {
194       Error = (Twine("malformed regex in line ") + Twine(LineNo) + ": '" +
195                SplitLine.second + "': " + REError).str();
196       return false;
197     }
198   }
199   return true;
200 }
201 
202 SpecialCaseList::~SpecialCaseList() {}
203 
204 bool SpecialCaseList::inSection(StringRef Section, StringRef Prefix,
205                                 StringRef Query, StringRef Category) const {
206   return inSectionBlame(Section, Prefix, Query, Category);
207 }
208 
209 unsigned SpecialCaseList::inSectionBlame(StringRef Section, StringRef Prefix,
210                                          StringRef Query,
211                                          StringRef Category) const {
212   for (auto &SectionIter : Sections)
213     if (SectionIter.SectionMatcher->match(Section)) {
214       unsigned Blame =
215           inSectionBlame(SectionIter.Entries, Prefix, Query, Category);
216       if (Blame)
217         return Blame;
218     }
219   return 0;
220 }
221 
222 unsigned SpecialCaseList::inSectionBlame(const SectionEntries &Entries,
223                                          StringRef Prefix, StringRef Query,
224                                          StringRef Category) const {
225   SectionEntries::const_iterator I = Entries.find(Prefix);
226   if (I == Entries.end()) return 0;
227   StringMap<Matcher>::const_iterator II = I->second.find(Category);
228   if (II == I->second.end()) return 0;
229 
230   return II->getValue().match(Query);
231 }
232 
233 }  // namespace llvm
234