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1 //===-- SpecialCaseList.cpp - special case list for sanitizers ------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This is a utility class for instrumentation passes (like AddressSanitizer
11 // or ThreadSanitizer) to avoid instrumenting some functions or global
12 // variables, or to instrument some functions or global variables in a specific
13 // way, based on a user-supplied list.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #include "llvm/Support/SpecialCaseList.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringExtras.h"
20 #include "llvm/ADT/StringSet.h"
21 #include "llvm/Support/MemoryBuffer.h"
22 #include "llvm/Support/Regex.h"
23 #include <string>
24 #include <system_error>
25 #include <utility>
26 
27 namespace llvm {
28 
29 /// Represents a set of regular expressions.  Regular expressions which are
30 /// "literal" (i.e. no regex metacharacters) are stored in Strings, while all
31 /// others are represented as a single pipe-separated regex in RegEx.  The
32 /// reason for doing so is efficiency; StringSet is much faster at matching
33 /// literal strings than Regex.
34 struct SpecialCaseList::Entry {
Entryllvm::SpecialCaseList::Entry35   Entry() {}
Entryllvm::SpecialCaseList::Entry36   Entry(Entry &&Other)
37       : Strings(std::move(Other.Strings)), RegEx(std::move(Other.RegEx)) {}
38 
39   StringSet<> Strings;
40   std::unique_ptr<Regex> RegEx;
41 
matchllvm::SpecialCaseList::Entry42   bool match(StringRef Query) const {
43     return Strings.count(Query) || (RegEx && RegEx->match(Query));
44   }
45 };
46 
SpecialCaseList()47 SpecialCaseList::SpecialCaseList() : Entries(), Regexps(), IsCompiled(false) {}
48 
49 std::unique_ptr<SpecialCaseList>
create(const std::vector<std::string> & Paths,std::string & Error)50 SpecialCaseList::create(const std::vector<std::string> &Paths,
51                         std::string &Error) {
52   std::unique_ptr<SpecialCaseList> SCL(new SpecialCaseList());
53   for (const auto &Path : Paths) {
54     ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
55         MemoryBuffer::getFile(Path);
56     if (std::error_code EC = FileOrErr.getError()) {
57       Error = (Twine("can't open file '") + Path + "': " + EC.message()).str();
58       return nullptr;
59     }
60     std::string ParseError;
61     if (!SCL->parse(FileOrErr.get().get(), ParseError)) {
62       Error = (Twine("error parsing file '") + Path + "': " + ParseError).str();
63       return nullptr;
64     }
65   }
66   SCL->compile();
67   return SCL;
68 }
69 
create(const MemoryBuffer * MB,std::string & Error)70 std::unique_ptr<SpecialCaseList> SpecialCaseList::create(const MemoryBuffer *MB,
71                                                          std::string &Error) {
72   std::unique_ptr<SpecialCaseList> SCL(new SpecialCaseList());
73   if (!SCL->parse(MB, Error))
74     return nullptr;
75   SCL->compile();
76   return SCL;
77 }
78 
79 std::unique_ptr<SpecialCaseList>
createOrDie(const std::vector<std::string> & Paths)80 SpecialCaseList::createOrDie(const std::vector<std::string> &Paths) {
81   std::string Error;
82   if (auto SCL = create(Paths, Error))
83     return SCL;
84   report_fatal_error(Error);
85 }
86 
parse(const MemoryBuffer * MB,std::string & Error)87 bool SpecialCaseList::parse(const MemoryBuffer *MB, std::string &Error) {
88   // Iterate through each line in the blacklist file.
89   SmallVector<StringRef, 16> Lines;
90   SplitString(MB->getBuffer(), Lines, "\n\r");
91   int LineNo = 1;
92   for (auto I = Lines.begin(), E = Lines.end(); I != E; ++I, ++LineNo) {
93     // Ignore empty lines and lines starting with "#"
94     if (I->empty() || I->startswith("#"))
95       continue;
96     // Get our prefix and unparsed regexp.
97     std::pair<StringRef, StringRef> SplitLine = I->split(":");
98     StringRef Prefix = SplitLine.first;
99     if (SplitLine.second.empty()) {
100       // Missing ':' in the line.
101       Error = (Twine("malformed line ") + Twine(LineNo) + ": '" +
102                SplitLine.first + "'").str();
103       return false;
104     }
105 
106     std::pair<StringRef, StringRef> SplitRegexp = SplitLine.second.split("=");
107     std::string Regexp = SplitRegexp.first;
108     StringRef Category = SplitRegexp.second;
109 
110     // See if we can store Regexp in Strings.
111     if (Regex::isLiteralERE(Regexp)) {
112       Entries[Prefix][Category].Strings.insert(Regexp);
113       continue;
114     }
115 
116     // Replace * with .*
117     for (size_t pos = 0; (pos = Regexp.find("*", pos)) != std::string::npos;
118          pos += strlen(".*")) {
119       Regexp.replace(pos, strlen("*"), ".*");
120     }
121 
122     // Check that the regexp is valid.
123     Regex CheckRE(Regexp);
124     std::string REError;
125     if (!CheckRE.isValid(REError)) {
126       Error = (Twine("malformed regex in line ") + Twine(LineNo) + ": '" +
127                SplitLine.second + "': " + REError).str();
128       return false;
129     }
130 
131     // Add this regexp into the proper group by its prefix.
132     if (!Regexps[Prefix][Category].empty())
133       Regexps[Prefix][Category] += "|";
134     Regexps[Prefix][Category] += "^" + Regexp + "$";
135   }
136   return true;
137 }
138 
compile()139 void SpecialCaseList::compile() {
140   assert(!IsCompiled && "compile() should only be called once");
141   // Iterate through each of the prefixes, and create Regexs for them.
142   for (StringMap<StringMap<std::string>>::const_iterator I = Regexps.begin(),
143                                                          E = Regexps.end();
144        I != E; ++I) {
145     for (StringMap<std::string>::const_iterator II = I->second.begin(),
146                                                 IE = I->second.end();
147          II != IE; ++II) {
148       Entries[I->getKey()][II->getKey()].RegEx.reset(new Regex(II->getValue()));
149     }
150   }
151   Regexps.clear();
152   IsCompiled = true;
153 }
154 
~SpecialCaseList()155 SpecialCaseList::~SpecialCaseList() {}
156 
inSection(StringRef Section,StringRef Query,StringRef Category) const157 bool SpecialCaseList::inSection(StringRef Section, StringRef Query,
158                                 StringRef Category) const {
159   assert(IsCompiled && "SpecialCaseList::compile() was not called!");
160   StringMap<StringMap<Entry> >::const_iterator I = Entries.find(Section);
161   if (I == Entries.end()) return false;
162   StringMap<Entry>::const_iterator II = I->second.find(Category);
163   if (II == I->second.end()) return false;
164 
165   return II->getValue().match(Query);
166 }
167 
168 }  // namespace llvm
169