forked from OSchip/llvm-project
427 lines
16 KiB
C++
427 lines
16 KiB
C++
//== ValistChecker.cpp - stdarg.h macro usage checker -----------*- 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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// This defines checkers which detect usage of uninitialized va_list values
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// and va_start calls with no matching va_end.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/CheckerManager.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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using namespace clang;
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using namespace ento;
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REGISTER_SET_WITH_PROGRAMSTATE(InitializedVALists, const MemRegion *)
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namespace {
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typedef SmallVector<const MemRegion *, 2> RegionVector;
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class ValistChecker : public Checker<check::PreCall, check::PreStmt<VAArgExpr>,
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check::DeadSymbols> {
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mutable std::unique_ptr<BugType> BT_leakedvalist, BT_uninitaccess;
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struct VAListAccepter {
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CallDescription Func;
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int VAListPos;
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};
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static const SmallVector<VAListAccepter, 15> VAListAccepters;
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static const CallDescription VaStart, VaEnd, VaCopy;
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public:
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enum CheckKind {
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CK_Uninitialized,
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CK_Unterminated,
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CK_CopyToSelf,
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CK_NumCheckKinds
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};
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DefaultBool ChecksEnabled[CK_NumCheckKinds];
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CheckerNameRef CheckNames[CK_NumCheckKinds];
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void checkPreStmt(const VAArgExpr *VAA, CheckerContext &C) const;
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void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
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void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
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private:
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const MemRegion *getVAListAsRegion(SVal SV, const Expr *VAExpr,
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bool &IsSymbolic, CheckerContext &C) const;
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const ExplodedNode *getStartCallSite(const ExplodedNode *N,
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const MemRegion *Reg) const;
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void reportUninitializedAccess(const MemRegion *VAList, StringRef Msg,
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CheckerContext &C) const;
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void reportLeakedVALists(const RegionVector &LeakedVALists, StringRef Msg1,
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StringRef Msg2, CheckerContext &C, ExplodedNode *N,
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bool ReportUninit = false) const;
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void checkVAListStartCall(const CallEvent &Call, CheckerContext &C,
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bool IsCopy) const;
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void checkVAListEndCall(const CallEvent &Call, CheckerContext &C) const;
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class ValistBugVisitor : public BugReporterVisitor {
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public:
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ValistBugVisitor(const MemRegion *Reg, bool IsLeak = false)
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: Reg(Reg), IsLeak(IsLeak) {}
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void Profile(llvm::FoldingSetNodeID &ID) const override {
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static int X = 0;
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ID.AddPointer(&X);
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ID.AddPointer(Reg);
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}
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PathDiagnosticPieceRef getEndPath(BugReporterContext &BRC,
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const ExplodedNode *EndPathNode,
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PathSensitiveBugReport &BR) override {
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if (!IsLeak)
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return nullptr;
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PathDiagnosticLocation L = BR.getLocation();
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// Do not add the statement itself as a range in case of leak.
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return std::make_shared<PathDiagnosticEventPiece>(L, BR.getDescription(),
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false);
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}
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PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
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BugReporterContext &BRC,
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PathSensitiveBugReport &BR) override;
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private:
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const MemRegion *Reg;
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bool IsLeak;
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};
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};
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const SmallVector<ValistChecker::VAListAccepter, 15>
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ValistChecker::VAListAccepters = {
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{{"vfprintf", 3}, 2},
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{{"vfscanf", 3}, 2},
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{{"vprintf", 2}, 1},
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{{"vscanf", 2}, 1},
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{{"vsnprintf", 4}, 3},
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{{"vsprintf", 3}, 2},
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{{"vsscanf", 3}, 2},
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{{"vfwprintf", 3}, 2},
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{{"vfwscanf", 3}, 2},
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{{"vwprintf", 2}, 1},
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{{"vwscanf", 2}, 1},
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{{"vswprintf", 4}, 3},
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// vswprintf is the wide version of vsnprintf,
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// vsprintf has no wide version
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{{"vswscanf", 3}, 2}};
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const CallDescription
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ValistChecker::VaStart("__builtin_va_start", /*Args=*/2, /*Params=*/1),
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ValistChecker::VaCopy("__builtin_va_copy", 2),
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ValistChecker::VaEnd("__builtin_va_end", 1);
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} // end anonymous namespace
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void ValistChecker::checkPreCall(const CallEvent &Call,
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CheckerContext &C) const {
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if (!Call.isGlobalCFunction())
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return;
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if (VaStart.matches(Call))
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checkVAListStartCall(Call, C, false);
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else if (VaCopy.matches(Call))
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checkVAListStartCall(Call, C, true);
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else if (VaEnd.matches(Call))
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checkVAListEndCall(Call, C);
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else {
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for (auto FuncInfo : VAListAccepters) {
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if (!FuncInfo.Func.matches(Call))
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continue;
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bool Symbolic;
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const MemRegion *VAList =
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getVAListAsRegion(Call.getArgSVal(FuncInfo.VAListPos),
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Call.getArgExpr(FuncInfo.VAListPos), Symbolic, C);
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if (!VAList)
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return;
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if (C.getState()->contains<InitializedVALists>(VAList))
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return;
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// We did not see va_start call, but the source of the region is unknown.
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// Be conservative and assume the best.
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if (Symbolic)
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return;
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SmallString<80> Errmsg("Function '");
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Errmsg += FuncInfo.Func.getFunctionName();
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Errmsg += "' is called with an uninitialized va_list argument";
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reportUninitializedAccess(VAList, Errmsg.c_str(), C);
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break;
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}
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}
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}
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const MemRegion *ValistChecker::getVAListAsRegion(SVal SV, const Expr *E,
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bool &IsSymbolic,
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CheckerContext &C) const {
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const MemRegion *Reg = SV.getAsRegion();
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if (!Reg)
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return nullptr;
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// TODO: In the future this should be abstracted away by the analyzer.
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bool VaListModelledAsArray = false;
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if (const auto *Cast = dyn_cast<CastExpr>(E)) {
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QualType Ty = Cast->getType();
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VaListModelledAsArray =
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Ty->isPointerType() && Ty->getPointeeType()->isRecordType();
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}
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if (const auto *DeclReg = Reg->getAs<DeclRegion>()) {
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if (isa<ParmVarDecl>(DeclReg->getDecl()))
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Reg = C.getState()->getSVal(SV.castAs<Loc>()).getAsRegion();
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}
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IsSymbolic = Reg && Reg->getAs<SymbolicRegion>();
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// Some VarRegion based VA lists reach here as ElementRegions.
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const auto *EReg = dyn_cast_or_null<ElementRegion>(Reg);
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return (EReg && VaListModelledAsArray) ? EReg->getSuperRegion() : Reg;
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}
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void ValistChecker::checkPreStmt(const VAArgExpr *VAA,
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CheckerContext &C) const {
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ProgramStateRef State = C.getState();
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const Expr *VASubExpr = VAA->getSubExpr();
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SVal VAListSVal = C.getSVal(VASubExpr);
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bool Symbolic;
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const MemRegion *VAList =
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getVAListAsRegion(VAListSVal, VASubExpr, Symbolic, C);
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if (!VAList)
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return;
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if (Symbolic)
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return;
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if (!State->contains<InitializedVALists>(VAList))
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reportUninitializedAccess(
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VAList, "va_arg() is called on an uninitialized va_list", C);
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}
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void ValistChecker::checkDeadSymbols(SymbolReaper &SR,
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CheckerContext &C) const {
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ProgramStateRef State = C.getState();
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InitializedVAListsTy TrackedVALists = State->get<InitializedVALists>();
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RegionVector LeakedVALists;
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for (auto Reg : TrackedVALists) {
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if (SR.isLiveRegion(Reg))
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continue;
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LeakedVALists.push_back(Reg);
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State = State->remove<InitializedVALists>(Reg);
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}
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if (ExplodedNode *N = C.addTransition(State))
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reportLeakedVALists(LeakedVALists, "Initialized va_list", " is leaked", C,
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N);
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}
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// This function traverses the exploded graph backwards and finds the node where
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// the va_list is initialized. That node is used for uniquing the bug paths.
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// It is not likely that there are several different va_lists that belongs to
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// different stack frames, so that case is not yet handled.
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const ExplodedNode *
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ValistChecker::getStartCallSite(const ExplodedNode *N,
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const MemRegion *Reg) const {
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const LocationContext *LeakContext = N->getLocationContext();
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const ExplodedNode *StartCallNode = N;
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bool FoundInitializedState = false;
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while (N) {
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ProgramStateRef State = N->getState();
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if (!State->contains<InitializedVALists>(Reg)) {
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if (FoundInitializedState)
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break;
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} else {
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FoundInitializedState = true;
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}
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const LocationContext *NContext = N->getLocationContext();
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if (NContext == LeakContext || NContext->isParentOf(LeakContext))
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StartCallNode = N;
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N = N->pred_empty() ? nullptr : *(N->pred_begin());
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}
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return StartCallNode;
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}
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void ValistChecker::reportUninitializedAccess(const MemRegion *VAList,
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StringRef Msg,
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CheckerContext &C) const {
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if (!ChecksEnabled[CK_Uninitialized])
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return;
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if (ExplodedNode *N = C.generateErrorNode()) {
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if (!BT_uninitaccess)
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BT_uninitaccess.reset(new BugType(CheckNames[CK_Uninitialized],
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"Uninitialized va_list",
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categories::MemoryError));
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auto R = std::make_unique<PathSensitiveBugReport>(*BT_uninitaccess, Msg, N);
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R->markInteresting(VAList);
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R->addVisitor(std::make_unique<ValistBugVisitor>(VAList));
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C.emitReport(std::move(R));
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}
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}
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void ValistChecker::reportLeakedVALists(const RegionVector &LeakedVALists,
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StringRef Msg1, StringRef Msg2,
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CheckerContext &C, ExplodedNode *N,
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bool ReportUninit) const {
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if (!(ChecksEnabled[CK_Unterminated] ||
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(ChecksEnabled[CK_Uninitialized] && ReportUninit)))
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return;
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for (auto Reg : LeakedVALists) {
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if (!BT_leakedvalist) {
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// FIXME: maybe creating a new check name for this type of bug is a better
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// solution.
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BT_leakedvalist.reset(
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new BugType(CheckNames[CK_Unterminated].getName().empty()
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? CheckNames[CK_Uninitialized]
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: CheckNames[CK_Unterminated],
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"Leaked va_list", categories::MemoryError,
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/*SuppressOnSink=*/true));
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}
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const ExplodedNode *StartNode = getStartCallSite(N, Reg);
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PathDiagnosticLocation LocUsedForUniqueing;
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if (const Stmt *StartCallStmt = StartNode->getStmtForDiagnostics())
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LocUsedForUniqueing = PathDiagnosticLocation::createBegin(
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StartCallStmt, C.getSourceManager(), StartNode->getLocationContext());
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SmallString<100> Buf;
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llvm::raw_svector_ostream OS(Buf);
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OS << Msg1;
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std::string VariableName = Reg->getDescriptiveName();
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if (!VariableName.empty())
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OS << " " << VariableName;
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OS << Msg2;
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auto R = std::make_unique<PathSensitiveBugReport>(
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*BT_leakedvalist, OS.str(), N, LocUsedForUniqueing,
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StartNode->getLocationContext()->getDecl());
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R->markInteresting(Reg);
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R->addVisitor(std::make_unique<ValistBugVisitor>(Reg, true));
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C.emitReport(std::move(R));
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}
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}
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void ValistChecker::checkVAListStartCall(const CallEvent &Call,
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CheckerContext &C, bool IsCopy) const {
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bool Symbolic;
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const MemRegion *VAList =
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getVAListAsRegion(Call.getArgSVal(0), Call.getArgExpr(0), Symbolic, C);
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if (!VAList)
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return;
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ProgramStateRef State = C.getState();
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if (IsCopy) {
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const MemRegion *Arg2 =
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getVAListAsRegion(Call.getArgSVal(1), Call.getArgExpr(1), Symbolic, C);
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if (Arg2) {
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if (ChecksEnabled[CK_CopyToSelf] && VAList == Arg2) {
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RegionVector LeakedVALists{VAList};
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if (ExplodedNode *N = C.addTransition(State))
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reportLeakedVALists(LeakedVALists, "va_list",
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" is copied onto itself", C, N, true);
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return;
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} else if (!State->contains<InitializedVALists>(Arg2) && !Symbolic) {
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if (State->contains<InitializedVALists>(VAList)) {
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State = State->remove<InitializedVALists>(VAList);
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RegionVector LeakedVALists{VAList};
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if (ExplodedNode *N = C.addTransition(State))
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reportLeakedVALists(LeakedVALists, "Initialized va_list",
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" is overwritten by an uninitialized one", C, N,
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true);
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} else {
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reportUninitializedAccess(Arg2, "Uninitialized va_list is copied", C);
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}
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return;
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}
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}
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}
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if (State->contains<InitializedVALists>(VAList)) {
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RegionVector LeakedVALists{VAList};
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if (ExplodedNode *N = C.addTransition(State))
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reportLeakedVALists(LeakedVALists, "Initialized va_list",
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" is initialized again", C, N);
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return;
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}
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State = State->add<InitializedVALists>(VAList);
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C.addTransition(State);
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}
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void ValistChecker::checkVAListEndCall(const CallEvent &Call,
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CheckerContext &C) const {
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bool Symbolic;
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const MemRegion *VAList =
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getVAListAsRegion(Call.getArgSVal(0), Call.getArgExpr(0), Symbolic, C);
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if (!VAList)
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return;
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// We did not see va_start call, but the source of the region is unknown.
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// Be conservative and assume the best.
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if (Symbolic)
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return;
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if (!C.getState()->contains<InitializedVALists>(VAList)) {
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reportUninitializedAccess(
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VAList, "va_end() is called on an uninitialized va_list", C);
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return;
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}
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ProgramStateRef State = C.getState();
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State = State->remove<InitializedVALists>(VAList);
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C.addTransition(State);
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}
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PathDiagnosticPieceRef ValistChecker::ValistBugVisitor::VisitNode(
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const ExplodedNode *N, BugReporterContext &BRC, PathSensitiveBugReport &) {
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ProgramStateRef State = N->getState();
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ProgramStateRef StatePrev = N->getFirstPred()->getState();
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const Stmt *S = N->getStmtForDiagnostics();
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if (!S)
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return nullptr;
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StringRef Msg;
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if (State->contains<InitializedVALists>(Reg) &&
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!StatePrev->contains<InitializedVALists>(Reg))
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Msg = "Initialized va_list";
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else if (!State->contains<InitializedVALists>(Reg) &&
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StatePrev->contains<InitializedVALists>(Reg))
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Msg = "Ended va_list";
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if (Msg.empty())
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return nullptr;
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PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
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N->getLocationContext());
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return std::make_shared<PathDiagnosticEventPiece>(Pos, Msg, true);
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}
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void ento::registerValistBase(CheckerManager &mgr) {
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mgr.registerChecker<ValistChecker>();
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}
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bool ento::shouldRegisterValistBase(const CheckerManager &mgr) {
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return true;
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}
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#define REGISTER_CHECKER(name) \
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void ento::register##name##Checker(CheckerManager &mgr) { \
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ValistChecker *checker = mgr.getChecker<ValistChecker>(); \
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checker->ChecksEnabled[ValistChecker::CK_##name] = true; \
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checker->CheckNames[ValistChecker::CK_##name] = \
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mgr.getCurrentCheckerName(); \
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} \
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\
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bool ento::shouldRegister##name##Checker(const CheckerManager &mgr) { \
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return true; \
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}
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REGISTER_CHECKER(Uninitialized)
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REGISTER_CHECKER(Unterminated)
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REGISTER_CHECKER(CopyToSelf)
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