clang-tools 10.0.0

ProperlySeededRandomGeneratorCheck.cpp
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1 //===--- ProperlySeededRandomGeneratorCheck.cpp - clang-tidy---------------===//
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 #include "ProperlySeededRandomGeneratorCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "llvm/ADT/STLExtras.h"
13
14 using namespace clang::ast_matchers;
15
16 namespace clang {
17 namespace tidy {
18 namespace cert {
19
20 ProperlySeededRandomGeneratorCheck::ProperlySeededRandomGeneratorCheck(
21 StringRef Name, ClangTidyContext *Context)
22 : ClangTidyCheck(Name, Context),
23 RawDisallowedSeedTypes(
24 Options.get("DisallowedSeedTypes", "time_t,std::time_t")) {
25 StringRef(RawDisallowedSeedTypes).split(DisallowedSeedTypes, ',');
26 }
27
28 void ProperlySeededRandomGeneratorCheck::storeOptions(
29 ClangTidyOptions::OptionMap &Opts) {
30 Options.store(Opts, "DisallowedSeedTypes", RawDisallowedSeedTypes);
31 }
32
33 void ProperlySeededRandomGeneratorCheck::registerMatchers(MatchFinder *Finder) {
34 auto RandomGeneratorEngineDecl = cxxRecordDecl(hasAnyName(
35 "::std::linear_congruential_engine", "::std::mersenne_twister_engine",
36 "::std::subtract_with_carry_engine", "::std::discard_block_engine",
37 "::std::independent_bits_engine", "::std::shuffle_order_engine"));
38 auto RandomGeneratorEngineTypeMatcher = hasType(hasUnqualifiedDesugaredType(
39 recordType(hasDeclaration(RandomGeneratorEngineDecl))));
40
41 // std::mt19937 engine;
42 // engine.seed();
43 // ^
44 // engine.seed(1);
45 // ^
46 // const int x = 1;
47 // engine.seed(x);
48 // ^
49 Finder->addMatcher(
50 cxxMemberCallExpr(
51 has(memberExpr(has(declRefExpr(RandomGeneratorEngineTypeMatcher)),
52 member(hasName("seed")),
53 unless(hasDescendant(cxxThisExpr())))))
54 .bind("seed"),
55 this);
56
57 // std::mt19937 engine;
58 // ^
59 // std::mt19937 engine(1);
60 // ^
61 // const int x = 1;
62 // std::mt19937 engine(x);
63 // ^
64 Finder->addMatcher(
65 cxxConstructExpr(RandomGeneratorEngineTypeMatcher).bind("ctor"), this);
66
67 // srand();
68 // ^
69 // const int x = 1;
70 // srand(x);
71 // ^
72 Finder->addMatcher(
73 callExpr(callee(functionDecl(hasAnyName("::srand", "::std::srand"))))
74 .bind("srand"),
75 this);
76 }
77
78 void ProperlySeededRandomGeneratorCheck::check(
79 const MatchFinder::MatchResult &Result) {
80 const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructExpr>("ctor");
81 if (Ctor)
82 checkSeed(Result, Ctor);
83
84 const auto *Func = Result.Nodes.getNodeAs<CXXMemberCallExpr>("seed");
85 if (Func)
86 checkSeed(Result, Func);
87
88 const auto *Srand = Result.Nodes.getNodeAs<CallExpr>("srand");
89 if (Srand)
90 checkSeed(Result, Srand);
91 }
92
93 template <class T>
94 void ProperlySeededRandomGeneratorCheck::checkSeed(
95 const MatchFinder::MatchResult &Result, const T *Func) {
96 if (Func->getNumArgs() == 0 || Func->getArg(0)->isDefaultArgument()) {
97 diag(Func->getExprLoc(),
98 "random number generator seeded with a default argument will generate "
99 "a predictable sequence of values");
100 return;
101 }
102
103 Expr::EvalResult EVResult;
104 if (Func->getArg(0)->EvaluateAsInt(EVResult, *Result.Context)) {
105 diag(Func->getExprLoc(),
106 "random number generator seeded with a constant value will generate a "
107 "predictable sequence of values");
108 return;
109 }
110
111 const std::string SeedType(
112 Func->getArg(0)->IgnoreCasts()->getType().getAsString());
113 if (llvm::find(DisallowedSeedTypes, SeedType) != DisallowedSeedTypes.end()) {
114 diag(Func->getExprLoc(),
115 "random number generator seeded with a disallowed source of seed "
116 "value will generate a predictable sequence of values");
117 return;
118 }
119 }
120
121 } // namespace cert
122 } // namespace tidy
123 } // namespace clang
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::tidy::cert::ProperlySeededRandomGeneratorCheck::registerMatchers
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Definition: ProperlySeededRandomGeneratorCheck.cpp:33
clang::tidy::ClangTidyCheck
Base class for all clang-tidy checks.
Definition: ClangTidyCheck.h:47
clang::tidy::ClangTidyCheck::Options
OptionsView Options
Definition: ClangTidyCheck.h:184
ProperlySeededRandomGeneratorCheck.h
clang::tidy::ClangTidyCheck::OptionsView::store
void store(ClangTidyOptions::OptionMap &Options, StringRef LocalName, StringRef Value) const
Stores an option with the check-local name LocalName with string value Value to Options.
Definition: ClangTidyCheck.cpp:58
clang::tidy::cert::ProperlySeededRandomGeneratorCheck::storeOptions
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
Definition: ProperlySeededRandomGeneratorCheck.cpp:28
Name
static constexpr llvm::StringLiteral Name
Definition: UppercaseLiteralSuffixCheck.cpp:27
clang::tidy::ClangTidyOptions::OptionMap
std::map< std::string, std::string > OptionMap
Definition: ClangTidyOptions.h:97
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::tidy::ClangTidyContext
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
Definition: ClangTidyDiagnosticConsumer.h:77
clang::tidy::cert::ProperlySeededRandomGeneratorCheck::check
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Definition: ProperlySeededRandomGeneratorCheck.cpp:78
clang::tidy::ClangTidyCheck::diag
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check&#39;s name.
Definition: ClangTidyCheck.cpp:21