forked from OSchip/llvm-project
141 lines
4.6 KiB
C++
141 lines
4.6 KiB
C++
//==- NonnullGlobalConstantsChecker.cpp ---------------------------*- C++ -*--//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This checker adds an assumption that constant globals of certain types* are
|
|
// non-null, as otherwise they generally do not convey any useful information.
|
|
// The assumption is useful, as many framework use e. g. global const strings,
|
|
// and the analyzer might not be able to infer the global value if the
|
|
// definition is in a separate translation unit.
|
|
// The following types (and their typedef aliases) are considered to be
|
|
// non-null:
|
|
// - `char* const`
|
|
// - `const CFStringRef` from CoreFoundation
|
|
// - `NSString* const` from Foundation
|
|
// - `CFBooleanRef` from Foundation
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "ClangSACheckers.h"
|
|
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
|
|
#include "clang/StaticAnalyzer/Core/Checker.h"
|
|
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
|
|
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
|
|
#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
|
|
|
|
using namespace clang;
|
|
using namespace ento;
|
|
|
|
namespace {
|
|
|
|
class NonnullGlobalConstantsChecker : public Checker<check::Location> {
|
|
mutable IdentifierInfo *NSStringII = nullptr;
|
|
mutable IdentifierInfo *CFStringRefII = nullptr;
|
|
mutable IdentifierInfo *CFBooleanRefII = nullptr;
|
|
|
|
public:
|
|
NonnullGlobalConstantsChecker() {}
|
|
|
|
void checkLocation(SVal l, bool isLoad, const Stmt *S,
|
|
CheckerContext &C) const;
|
|
|
|
private:
|
|
void initIdentifierInfo(ASTContext &Ctx) const;
|
|
|
|
bool isGlobalConstString(SVal V) const;
|
|
|
|
bool isNonnullType(QualType Ty) const;
|
|
};
|
|
|
|
} // namespace
|
|
|
|
/// Lazily initialize cache for required identifier information.
|
|
void NonnullGlobalConstantsChecker::initIdentifierInfo(ASTContext &Ctx) const {
|
|
if (NSStringII)
|
|
return;
|
|
|
|
NSStringII = &Ctx.Idents.get("NSString");
|
|
CFStringRefII = &Ctx.Idents.get("CFStringRef");
|
|
CFBooleanRefII = &Ctx.Idents.get("CFBooleanRef");
|
|
}
|
|
|
|
/// Add an assumption that const string-like globals are non-null.
|
|
void NonnullGlobalConstantsChecker::checkLocation(SVal location, bool isLoad,
|
|
const Stmt *S,
|
|
CheckerContext &C) const {
|
|
initIdentifierInfo(C.getASTContext());
|
|
if (!isLoad || !location.isValid())
|
|
return;
|
|
|
|
ProgramStateRef State = C.getState();
|
|
|
|
if (isGlobalConstString(location)) {
|
|
SVal V = State->getSVal(location.castAs<Loc>());
|
|
Optional<DefinedOrUnknownSVal> Constr = V.getAs<DefinedOrUnknownSVal>();
|
|
|
|
if (Constr) {
|
|
|
|
// Assume that the variable is non-null.
|
|
ProgramStateRef OutputState = State->assume(*Constr, true);
|
|
C.addTransition(OutputState);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// \param V loaded lvalue.
|
|
/// \return whether {@code val} is a string-like const global.
|
|
bool NonnullGlobalConstantsChecker::isGlobalConstString(SVal V) const {
|
|
Optional<loc::MemRegionVal> RegionVal = V.getAs<loc::MemRegionVal>();
|
|
if (!RegionVal)
|
|
return false;
|
|
auto *Region = dyn_cast<VarRegion>(RegionVal->getAsRegion());
|
|
if (!Region)
|
|
return false;
|
|
const VarDecl *Decl = Region->getDecl();
|
|
|
|
if (!Decl->hasGlobalStorage())
|
|
return false;
|
|
|
|
QualType Ty = Decl->getType();
|
|
bool HasConst = Ty.isConstQualified();
|
|
if (isNonnullType(Ty) && HasConst)
|
|
return true;
|
|
|
|
// Look through the typedefs.
|
|
while (auto *T = dyn_cast<TypedefType>(Ty)) {
|
|
Ty = T->getDecl()->getUnderlyingType();
|
|
|
|
// It is sufficient for any intermediate typedef
|
|
// to be classified const.
|
|
HasConst = HasConst || Ty.isConstQualified();
|
|
if (isNonnullType(Ty) && HasConst)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// \return whether {@code type} is extremely unlikely to be null
|
|
bool NonnullGlobalConstantsChecker::isNonnullType(QualType Ty) const {
|
|
|
|
if (Ty->isPointerType() && Ty->getPointeeType()->isCharType())
|
|
return true;
|
|
|
|
if (auto *T = dyn_cast<ObjCObjectPointerType>(Ty)) {
|
|
return T->getInterfaceDecl() &&
|
|
T->getInterfaceDecl()->getIdentifier() == NSStringII;
|
|
} else if (auto *T = dyn_cast<TypedefType>(Ty)) {
|
|
IdentifierInfo* II = T->getDecl()->getIdentifier();
|
|
return II == CFStringRefII || II == CFBooleanRefII;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
void ento::registerNonnullGlobalConstantsChecker(CheckerManager &Mgr) {
|
|
Mgr.registerChecker<NonnullGlobalConstantsChecker>();
|
|
}
|