| //===--- SuspiciousMemoryComparisonCheck.cpp - clang-tidy -----------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "SuspiciousMemoryComparisonCheck.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/ASTMatchers/ASTMatchFinder.h" |
| |
| using namespace clang::ast_matchers; |
| |
| namespace clang { |
| namespace tidy { |
| namespace bugprone { |
| |
| static llvm::Optional<uint64_t> tryEvaluateSizeExpr(const Expr *SizeExpr, |
| const ASTContext &Ctx) { |
| Expr::EvalResult Result; |
| if (SizeExpr->EvaluateAsRValue(Result, Ctx)) |
| return Ctx.toBits( |
| CharUnits::fromQuantity(Result.Val.getInt().getExtValue())); |
| return None; |
| } |
| |
| void SuspiciousMemoryComparisonCheck::registerMatchers(MatchFinder *Finder) { |
| Finder->addMatcher( |
| callExpr(allOf(callee(namedDecl( |
| anyOf(hasName("::memcmp"), hasName("::std::memcmp")))), |
| unless(isInstantiationDependent()))) |
| .bind("call"), |
| this); |
| } |
| |
| void SuspiciousMemoryComparisonCheck::check( |
| const MatchFinder::MatchResult &Result) { |
| const ASTContext &Ctx = *Result.Context; |
| const auto *CE = Result.Nodes.getNodeAs<CallExpr>("call"); |
| |
| const Expr *SizeExpr = CE->getArg(2); |
| assert(SizeExpr != nullptr && "Third argument of memcmp is mandatory."); |
| llvm::Optional<uint64_t> ComparedBits = tryEvaluateSizeExpr(SizeExpr, Ctx); |
| |
| for (unsigned int ArgIndex = 0; ArgIndex < 2; ++ArgIndex) { |
| const Expr *ArgExpr = CE->getArg(ArgIndex); |
| QualType ArgType = ArgExpr->IgnoreImplicit()->getType(); |
| const Type *PointeeType = ArgType->getPointeeOrArrayElementType(); |
| assert(PointeeType != nullptr && "PointeeType should always be available."); |
| QualType PointeeQualifiedType(PointeeType, 0); |
| |
| if (PointeeType->isRecordType()) { |
| if (const RecordDecl *RD = |
| PointeeType->getAsRecordDecl()->getDefinition()) { |
| if (const auto *CXXDecl = dyn_cast<CXXRecordDecl>(RD)) { |
| if (!CXXDecl->isStandardLayout()) { |
| diag(CE->getBeginLoc(), |
| "comparing object representation of non-standard-layout type " |
| "%0; consider using a comparison operator instead") |
| << PointeeQualifiedType; |
| break; |
| } |
| } |
| } |
| } |
| |
| if (!PointeeType->isIncompleteType()) { |
| uint64_t PointeeSize = Ctx.getTypeSize(PointeeType); |
| if (ComparedBits.hasValue() && *ComparedBits >= PointeeSize && |
| !Ctx.hasUniqueObjectRepresentations(PointeeQualifiedType)) { |
| diag(CE->getBeginLoc(), |
| "comparing object representation of type %0 which does not have a " |
| "unique object representation; consider comparing %select{the " |
| "values|the members of the object}1 manually") |
| << PointeeQualifiedType << (PointeeType->isRecordType() ? 1 : 0); |
| break; |
| } |
| } |
| } |
| } |
| |
| } // namespace bugprone |
| } // namespace tidy |
| } // namespace clang |