10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "llvm/ADT/STLExtras.h"
20 ProperlySeededRandomGeneratorCheck::ProperlySeededRandomGeneratorCheck(
23 RawDisallowedSeedTypes(
24 Options.get(
"DisallowedSeedTypes",
"time_t,std::time_t")) {
25 StringRef(RawDisallowedSeedTypes).split(DisallowedSeedTypes,
',');
30 Options.
store(Opts,
"DisallowedSeedTypes", RawDisallowedSeedTypes);
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))));
51 has(memberExpr(has(declRefExpr(RandomGeneratorEngineTypeMatcher)),
52 member(hasName(
"seed")),
53 unless(hasDescendant(cxxThisExpr())))))
65 traverse(ast_type_traits::TK_AsIs,
66 cxxConstructExpr(RandomGeneratorEngineTypeMatcher).bind(
"ctor")),
75 callExpr(callee(functionDecl(hasAnyName(
"::srand",
"::std::srand"))))
81 const MatchFinder::MatchResult &Result) {
82 const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructExpr>(
"ctor");
84 checkSeed(Result, Ctor);
86 const auto *Func = Result.Nodes.getNodeAs<CXXMemberCallExpr>(
"seed");
88 checkSeed(Result, Func);
90 const auto *Srand = Result.Nodes.getNodeAs<CallExpr>(
"srand");
92 checkSeed(Result, Srand);
96 void ProperlySeededRandomGeneratorCheck::checkSeed(
97 const MatchFinder::MatchResult &Result,
const T *Func) {
98 if (Func->getNumArgs() == 0 || Func->getArg(0)->isDefaultArgument()) {
99 diag(Func->getExprLoc(),
100 "random number generator seeded with a default argument will generate "
101 "a predictable sequence of values");
105 Expr::EvalResult EVResult;
106 if (Func->getArg(0)->EvaluateAsInt(EVResult, *Result.Context)) {
107 diag(Func->getExprLoc(),
108 "random number generator seeded with a constant value will generate a "
109 "predictable sequence of values");
113 const std::string SeedType(
114 Func->getArg(0)->IgnoreCasts()->getType().getAsString());
115 if (llvm::find(DisallowedSeedTypes, SeedType) != DisallowedSeedTypes.end()) {
116 diag(Func->getExprLoc(),
117 "random number generator seeded with a disallowed source of seed "
118 "value will generate a predictable sequence of values");