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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 {
     35   Entry() {}
     36   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 
     42   bool match(StringRef Query) const {
     43     return Strings.count(Query) || (RegEx && RegEx->match(Query));
     44   }
     45 };
     46 
     47 SpecialCaseList::SpecialCaseList() : Entries(), Regexps(), IsCompiled(false) {}
     48 
     49 std::unique_ptr<SpecialCaseList>
     50 SpecialCaseList::create(const std::vector<std::string> &Paths,
     51                         std::string &Error) {
     52   std::unique_ptr<SpecialCaseList> SCL(new SpecialCaseList());
     53   for (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 
     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>
     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 
     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 
    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 
    155 SpecialCaseList::~SpecialCaseList() {}
    156 
    157 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