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* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2017 Cppcheck team.
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <>.
#ifndef checknullpointerH
#define checknullpointerH
#include "check.h"
#include "config.h"
#include "valueflow.h"
#include <list>
#include <string>
class ErrorLogger;
class Library;
class Settings;
class Token;
class Tokenizer;
/// @addtogroup Checks
/// @{
/** @brief check for null pointer dereferencing */
class CPPCHECKLIB CheckNullPointer : public Check {
/** @brief This constructor is used when registering the CheckNullPointer */
CheckNullPointer() : Check(myName()) {
/** @brief This constructor is used when running checks. */
CheckNullPointer(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger)
: Check(myName(), tokenizer, settings, errorLogger) {
/** @brief Run checks against the normal token list */
void runChecks(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger) override {
CheckNullPointer checkNullPointer(tokenizer, settings, errorLogger);
/** @brief Run checks against the simplified token list */
void runSimplifiedChecks(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger) override {
CheckNullPointer checkNullPointer(tokenizer, settings, errorLogger);
* @brief parse a function call and extract information about variable usage
* @param tok first token
* @param var variables that the function read / write.
* @param library --library files data
static void parseFunctionCall(const Token &tok,
std::list<const Token *> &var,
const Library *library);
* Is there a pointer dereference? Everything that should result in
* a nullpointer dereference error message will result in a true
* return value. If it's unknown if the pointer is dereferenced false
* is returned.
* @param tok token for the pointer
* @param unknown it is not known if there is a pointer dereference (could be reported as a debug message)
* @return true => there is a dereference
static bool isPointerDeRef(const Token *tok, bool &unknown);
/** @brief possible null pointer dereference */
void nullPointer();
/** @brief dereferencing null constant (after Tokenizer::simplifyKnownVariables) */
void nullConstantDereference();
void nullPointerError(const Token *tok) {
ValueFlow::Value v(0);
nullPointerError(tok, "", &v, false);
void nullPointerError(const Token *tok, const std::string &varname, const ValueFlow::Value* value, bool inconclusive);
/** Get error messages. Used by --errorlist */
void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const override {
CheckNullPointer c(nullptr, settings, errorLogger);
c.nullPointerError(nullptr, "pointer", nullptr, false);
c.arithmeticError(nullptr, nullptr);
/** Name of check */
static std::string myName() {
return "Null pointer";
/** class info in WIKI format. Used by --doc */
std::string classInfo() const override {
return "Null pointers\n"
"- null pointer dereferencing\n"
"- undefined null pointer arithmetic\n";
* @brief Does one part of the check for nullPointer().
* looping through items in a linked list in a inner loop..
void nullPointerLinkedList();
* @brief Does one part of the check for nullPointer().
* Dereferencing a pointer and then checking if it's NULL..
void nullPointerByDeRefAndChec();
/** undefined null pointer arithmetic */
void arithmetic();
void arithmeticError(const Token *tok, const ValueFlow::Value *value);
/// @}
#endif // checknullpointerH