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