CastSizeChecker.cpp

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//=== CastSizeChecker.cpp ---------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// CastSizeChecker checks when casting a malloc'ed symbolic region to type T,
// whether the size of the symbolic region is a multiple of the size of T.
//
//===----------------------------------------------------------------------===//
 
#include "clang/AST/CharUnits.h"
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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/DynamicExtent.h"
 
using namespace clang;
using namespace ento;
 
namespace {
class CastSizeChecker : public Checker< check::PreStmt<CastExpr> > {
  const BugType BT{this, "Cast region with wrong size."};
 
public:
  void checkPreStmt(const CastExpr *CE, CheckerContext &C) const;
};
}
 
/// Check if we are casting to a struct with a flexible array at the end.
/// \code
/// struct foo {
///   size_t len;
///   struct bar data[];
/// };
/// \endcode
/// or
/// \code
/// struct foo {
///   size_t len;
///   struct bar data[0];
/// }
/// \endcode
/// In these cases it is also valid to allocate size of struct foo + a multiple
/// of struct bar.