320 lines
11 KiB
C++
320 lines
11 KiB
C++
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//=== Iterator.cpp - Common functions for iterator checkers. -------*- C++ -*-//
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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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//
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// Defines common functions to be used by the itertor checkers .
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//
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//===----------------------------------------------------------------------===//
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#include "Iterator.h"
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namespace clang {
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namespace ento {
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namespace iterator {
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bool isIteratorType(const QualType &Type) {
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if (Type->isPointerType())
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return true;
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const auto *CRD = Type->getUnqualifiedDesugaredType()->getAsCXXRecordDecl();
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return isIterator(CRD);
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}
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bool isIterator(const CXXRecordDecl *CRD) {
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if (!CRD)
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return false;
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const auto Name = CRD->getName();
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if (!(Name.endswith_lower("iterator") || Name.endswith_lower("iter") ||
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Name.endswith_lower("it")))
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return false;
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bool HasCopyCtor = false, HasCopyAssign = true, HasDtor = false,
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HasPreIncrOp = false, HasPostIncrOp = false, HasDerefOp = false;
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for (const auto *Method : CRD->methods()) {
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if (const auto *Ctor = dyn_cast<CXXConstructorDecl>(Method)) {
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if (Ctor->isCopyConstructor()) {
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HasCopyCtor = !Ctor->isDeleted() && Ctor->getAccess() == AS_public;
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}
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continue;
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}
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if (const auto *Dtor = dyn_cast<CXXDestructorDecl>(Method)) {
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HasDtor = !Dtor->isDeleted() && Dtor->getAccess() == AS_public;
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continue;
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}
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if (Method->isCopyAssignmentOperator()) {
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HasCopyAssign = !Method->isDeleted() && Method->getAccess() == AS_public;
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continue;
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}
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if (!Method->isOverloadedOperator())
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continue;
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const auto OPK = Method->getOverloadedOperator();
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if (OPK == OO_PlusPlus) {
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HasPreIncrOp = HasPreIncrOp || (Method->getNumParams() == 0);
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HasPostIncrOp = HasPostIncrOp || (Method->getNumParams() == 1);
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continue;
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}
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if (OPK == OO_Star) {
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HasDerefOp = (Method->getNumParams() == 0);
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continue;
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}
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}
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return HasCopyCtor && HasCopyAssign && HasDtor && HasPreIncrOp &&
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HasPostIncrOp && HasDerefOp;
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}
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bool isComparisonOperator(OverloadedOperatorKind OK) {
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return OK == OO_EqualEqual || OK == OO_ExclaimEqual || OK == OO_Less ||
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OK == OO_LessEqual || OK == OO_Greater || OK == OO_GreaterEqual;
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}
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bool isInsertCall(const FunctionDecl *Func) {
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const auto *IdInfo = Func->getIdentifier();
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if (!IdInfo)
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return false;
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if (Func->getNumParams() < 2 || Func->getNumParams() > 3)
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return false;
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if (!isIteratorType(Func->getParamDecl(0)->getType()))
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return false;
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return IdInfo->getName() == "insert";
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}
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bool isEmplaceCall(const FunctionDecl *Func) {
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const auto *IdInfo = Func->getIdentifier();
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if (!IdInfo)
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return false;
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if (Func->getNumParams() < 2)
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return false;
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if (!isIteratorType(Func->getParamDecl(0)->getType()))
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return false;
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return IdInfo->getName() == "emplace";
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}
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bool isEraseCall(const FunctionDecl *Func) {
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const auto *IdInfo = Func->getIdentifier();
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if (!IdInfo)
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return false;
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if (Func->getNumParams() < 1 || Func->getNumParams() > 2)
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return false;
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if (!isIteratorType(Func->getParamDecl(0)->getType()))
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return false;
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if (Func->getNumParams() == 2 &&
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!isIteratorType(Func->getParamDecl(1)->getType()))
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return false;
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return IdInfo->getName() == "erase";
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}
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bool isEraseAfterCall(const FunctionDecl *Func) {
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const auto *IdInfo = Func->getIdentifier();
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if (!IdInfo)
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return false;
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if (Func->getNumParams() < 1 || Func->getNumParams() > 2)
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return false;
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if (!isIteratorType(Func->getParamDecl(0)->getType()))
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return false;
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if (Func->getNumParams() == 2 &&
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!isIteratorType(Func->getParamDecl(1)->getType()))
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return false;
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return IdInfo->getName() == "erase_after";
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}
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bool isAccessOperator(OverloadedOperatorKind OK) {
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return isDereferenceOperator(OK) || isIncrementOperator(OK) ||
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isDecrementOperator(OK) || isRandomIncrOrDecrOperator(OK);
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}
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bool isAccessOperator(UnaryOperatorKind OK) {
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return isDereferenceOperator(OK) || isIncrementOperator(OK) ||
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isDecrementOperator(OK);
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}
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bool isAccessOperator(BinaryOperatorKind OK) {
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return isDereferenceOperator(OK) || isRandomIncrOrDecrOperator(OK);
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}
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bool isDereferenceOperator(OverloadedOperatorKind OK) {
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return OK == OO_Star || OK == OO_Arrow || OK == OO_ArrowStar ||
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OK == OO_Subscript;
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}
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bool isDereferenceOperator(UnaryOperatorKind OK) {
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return OK == UO_Deref;
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}
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bool isDereferenceOperator(BinaryOperatorKind OK) {
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return OK == BO_PtrMemI;
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}
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bool isIncrementOperator(OverloadedOperatorKind OK) {
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return OK == OO_PlusPlus;
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}
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bool isIncrementOperator(UnaryOperatorKind OK) {
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return OK == UO_PreInc || OK == UO_PostInc;
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}
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bool isDecrementOperator(OverloadedOperatorKind OK) {
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return OK == OO_MinusMinus;
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}
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bool isDecrementOperator(UnaryOperatorKind OK) {
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return OK == UO_PreDec || OK == UO_PostDec;
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}
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bool isRandomIncrOrDecrOperator(OverloadedOperatorKind OK) {
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return OK == OO_Plus || OK == OO_PlusEqual || OK == OO_Minus ||
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OK == OO_MinusEqual;
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}
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bool isRandomIncrOrDecrOperator(BinaryOperatorKind OK) {
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return OK == BO_Add || OK == BO_AddAssign ||
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OK == BO_Sub || OK == BO_SubAssign;
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}
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const ContainerData *getContainerData(ProgramStateRef State,
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const MemRegion *Cont) {
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return State->get<ContainerMap>(Cont);
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}
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const IteratorPosition *getIteratorPosition(ProgramStateRef State,
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const SVal &Val) {
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if (auto Reg = Val.getAsRegion()) {
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Reg = Reg->getMostDerivedObjectRegion();
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return State->get<IteratorRegionMap>(Reg);
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} else if (const auto Sym = Val.getAsSymbol()) {
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return State->get<IteratorSymbolMap>(Sym);
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} else if (const auto LCVal = Val.getAs<nonloc::LazyCompoundVal>()) {
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return State->get<IteratorRegionMap>(LCVal->getRegion());
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}
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return nullptr;
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}
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ProgramStateRef setIteratorPosition(ProgramStateRef State, const SVal &Val,
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const IteratorPosition &Pos) {
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if (auto Reg = Val.getAsRegion()) {
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Reg = Reg->getMostDerivedObjectRegion();
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return State->set<IteratorRegionMap>(Reg, Pos);
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} else if (const auto Sym = Val.getAsSymbol()) {
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return State->set<IteratorSymbolMap>(Sym, Pos);
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} else if (const auto LCVal = Val.getAs<nonloc::LazyCompoundVal>()) {
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return State->set<IteratorRegionMap>(LCVal->getRegion(), Pos);
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}
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return nullptr;
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}
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ProgramStateRef createIteratorPosition(ProgramStateRef State, const SVal &Val,
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const MemRegion *Cont, const Stmt* S,
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const LocationContext *LCtx,
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unsigned blockCount) {
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auto &StateMgr = State->getStateManager();
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auto &SymMgr = StateMgr.getSymbolManager();
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auto &ACtx = StateMgr.getContext();
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auto Sym = SymMgr.conjureSymbol(S, LCtx, ACtx.LongTy, blockCount);
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State = assumeNoOverflow(State, Sym, 4);
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return setIteratorPosition(State, Val,
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IteratorPosition::getPosition(Cont, Sym));
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}
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ProgramStateRef advancePosition(ProgramStateRef State, const SVal &Iter,
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OverloadedOperatorKind Op,
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const SVal &Distance) {
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const auto *Pos = getIteratorPosition(State, Iter);
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if (!Pos)
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return nullptr;
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auto &SymMgr = State->getStateManager().getSymbolManager();
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auto &SVB = State->getStateManager().getSValBuilder();
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auto &BVF = State->getStateManager().getBasicVals();
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assert ((Op == OO_Plus || Op == OO_PlusEqual ||
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Op == OO_Minus || Op == OO_MinusEqual) &&
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"Advance operator must be one of +, -, += and -=.");
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auto BinOp = (Op == OO_Plus || Op == OO_PlusEqual) ? BO_Add : BO_Sub;
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const auto IntDistOp = Distance.getAs<nonloc::ConcreteInt>();
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if (!IntDistOp)
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return nullptr;
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// For concrete integers we can calculate the new position
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nonloc::ConcreteInt IntDist = *IntDistOp;
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if (IntDist.getValue().isNegative()) {
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IntDist = nonloc::ConcreteInt(BVF.getValue(-IntDist.getValue()));
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BinOp = (BinOp == BO_Add) ? BO_Sub : BO_Add;
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}
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const auto NewPos =
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Pos->setTo(SVB.evalBinOp(State, BinOp,
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nonloc::SymbolVal(Pos->getOffset()),
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IntDist, SymMgr.getType(Pos->getOffset()))
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.getAsSymbol());
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return setIteratorPosition(State, Iter, NewPos);
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}
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// This function tells the analyzer's engine that symbols produced by our
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// checker, most notably iterator positions, are relatively small.
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// A distance between items in the container should not be very large.
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// By assuming that it is within around 1/8 of the address space,
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// we can help the analyzer perform operations on these symbols
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// without being afraid of integer overflows.
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// FIXME: Should we provide it as an API, so that all checkers could use it?
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ProgramStateRef assumeNoOverflow(ProgramStateRef State, SymbolRef Sym,
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long Scale) {
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SValBuilder &SVB = State->getStateManager().getSValBuilder();
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BasicValueFactory &BV = SVB.getBasicValueFactory();
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QualType T = Sym->getType();
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assert(T->isSignedIntegerOrEnumerationType());
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APSIntType AT = BV.getAPSIntType(T);
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ProgramStateRef NewState = State;
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llvm::APSInt Max = AT.getMaxValue() / AT.getValue(Scale);
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SVal IsCappedFromAbove =
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SVB.evalBinOpNN(State, BO_LE, nonloc::SymbolVal(Sym),
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nonloc::ConcreteInt(Max), SVB.getConditionType());
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if (auto DV = IsCappedFromAbove.getAs<DefinedSVal>()) {
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NewState = NewState->assume(*DV, true);
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if (!NewState)
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return State;
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}
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llvm::APSInt Min = -Max;
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SVal IsCappedFromBelow =
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SVB.evalBinOpNN(State, BO_GE, nonloc::SymbolVal(Sym),
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nonloc::ConcreteInt(Min), SVB.getConditionType());
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if (auto DV = IsCappedFromBelow.getAs<DefinedSVal>()) {
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NewState = NewState->assume(*DV, true);
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if (!NewState)
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return State;
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}
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return NewState;
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}
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bool compare(ProgramStateRef State, SymbolRef Sym1, SymbolRef Sym2,
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BinaryOperator::Opcode Opc) {
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return compare(State, nonloc::SymbolVal(Sym1), nonloc::SymbolVal(Sym2), Opc);
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}
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bool compare(ProgramStateRef State, NonLoc NL1, NonLoc NL2,
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BinaryOperator::Opcode Opc) {
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auto &SVB = State->getStateManager().getSValBuilder();
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const auto comparison =
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SVB.evalBinOp(State, Opc, NL1, NL2, SVB.getConditionType());
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assert(comparison.getAs<DefinedSVal>() &&
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"Symbol comparison must be a `DefinedSVal`");
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return !State->assume(comparison.castAs<DefinedSVal>(), false);
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}
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} // namespace iterator
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} // namespace ento
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} // namespace clang
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