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//=== VLASizeChecker.cpp - Undefined dereference checker --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This defines VLASizeChecker, a builtin check in GRExprEngine that
// performs checks for declaration of VLA of undefined or zero size.
//
//===----------------------------------------------------------------------===//
#include "GRExprEngineInternalChecks.h"
#include "clang/Analysis/PathSensitive/CheckerVisitor.h"
#include "clang/Analysis/PathSensitive/GRExprEngine.h"
#include "clang/Analysis/PathSensitive/BugReporter.h"
using namespace clang;
namespace {
class VISIBILITY_HIDDEN VLASizeChecker : public CheckerVisitor<VLASizeChecker> {
BugType *BT_zero;
BugType *BT_undef;
public:
VLASizeChecker() : BT_zero(0), BT_undef(0) {}
static void *getTag() { static int tag = 0; return &tag; }
void PreVisitDeclStmt(CheckerContext &C, const DeclStmt *DS);
};
} // end anonymous namespace
void clang::RegisterVLASizeChecker(GRExprEngine &Eng) {
Eng.registerCheck(new VLASizeChecker());
}
void VLASizeChecker::PreVisitDeclStmt(CheckerContext &C, const DeclStmt *DS) {
if (!DS->isSingleDecl())
return;
const VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl());
if (!VD)
return;
const VariableArrayType *VLA
= C.getASTContext().getAsVariableArrayType(VD->getType());
if (!VLA)
return;
// FIXME: Handle multi-dimensional VLAs.
const Expr* SE = VLA->getSizeExpr();
const GRState *state = C.getState();
SVal sizeV = state->getSVal(SE);
if (sizeV.isUndef()) {
// Generate an error node.
ExplodedNode *N = C.GenerateNode(DS, true);
if (!N)
return;
if (!BT_undef)
BT_undef = new BuiltinBug("Declared variable-length array (VLA) uses a "
"garbage value as its size");
EnhancedBugReport *report =
new EnhancedBugReport(*BT_undef, BT_undef->getName(), N);
report->addRange(SE->getSourceRange());
report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, SE);
C.EmitReport(report);
return;
}
// Check if the size is zero.
DefinedOrUnknownSVal sizeD = cast<DefinedOrUnknownSVal>(sizeV);
const GRState *stateNotZero, *stateZero;
llvm::tie(stateNotZero, stateZero) = state->Assume(sizeD);
if (stateZero && !stateNotZero) {
ExplodedNode* N = C.GenerateNode(DS, stateZero, true);
if (!BT_zero)
BT_zero = new BuiltinBug("Declared variable-length array (VLA) has zero "
"size");
EnhancedBugReport *report =
new EnhancedBugReport(*BT_zero, BT_zero->getName(), N);
report->addRange(SE->getSourceRange());
report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, SE);
C.EmitReport(report);
return;
}
// From this point on, assume that the size is not zero.
if (state != stateNotZero)
C.addTransition(C.GenerateNode(DS, stateNotZero));
}
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