1276 lines
48 KiB
C++
1276 lines
48 KiB
C++
/*
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* Cppcheck - A tool for static C/C++ code analysis
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* Copyright (C) 2007-2012 Daniel Marjamäki and Cppcheck team.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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//---------------------------------------------------------------------------
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#include "checknullpointer.h"
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#include "executionpath.h"
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#include "mathlib.h"
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#include "symboldatabase.h"
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#include <cctype>
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//---------------------------------------------------------------------------
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// Register this check class (by creating a static instance of it)
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namespace {
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CheckNullPointer instance;
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}
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//---------------------------------------------------------------------------
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/** Is string uppercase? */
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bool CheckNullPointer::isUpper(const std::string &str)
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{
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for (unsigned int i = 0; i < str.length(); ++i) {
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if (str[i] >= 'a' && str[i] <= 'z')
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return false;
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}
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return true;
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}
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/**
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* @brief parse a function call and extract information about variable usage
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* @param tok first token
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* @param var variables that the function read / write.
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* @param value 0 => invalid with null pointers as parameter.
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* 1-.. => invalid with uninitialized data.
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*/
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void CheckNullPointer::parseFunctionCall(const Token &tok, std::list<const Token *> &var, unsigned char value)
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{
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// standard functions that dereference first parameter..
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static std::set<std::string> functionNames1_all;
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static std::set<std::string> functionNames1_nullptr;
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if (functionNames1_all.empty()) {
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functionNames1_all.insert("memchr");
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functionNames1_all.insert("memcmp");
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functionNames1_all.insert("strcat");
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functionNames1_all.insert("strncat");
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functionNames1_all.insert("strchr");
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functionNames1_all.insert("strrchr");
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functionNames1_all.insert("strcmp");
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functionNames1_all.insert("strncmp");
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functionNames1_all.insert("strdup");
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functionNames1_all.insert("strndup");
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functionNames1_all.insert("strlen");
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functionNames1_all.insert("strstr");
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functionNames1_all.insert("fclose");
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functionNames1_all.insert("feof");
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functionNames1_all.insert("fwrite");
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functionNames1_all.insert("fseek");
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functionNames1_all.insert("ftell");
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functionNames1_all.insert("fgetpos");
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functionNames1_all.insert("fsetpos");
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functionNames1_all.insert("rewind");
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functionNames1_all.insert("printf");
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functionNames1_all.insert("scanf");
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functionNames1_all.insert("fscanf");
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functionNames1_all.insert("sscanf");
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functionNames1_nullptr.insert("memcpy");
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functionNames1_nullptr.insert("memmove");
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functionNames1_nullptr.insert("memset");
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functionNames1_nullptr.insert("strcpy");
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functionNames1_nullptr.insert("sprintf");
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functionNames1_nullptr.insert("vsprintf");
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functionNames1_nullptr.insert("vprintf");
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functionNames1_nullptr.insert("fprintf");
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functionNames1_nullptr.insert("vfprintf");
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}
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// standard functions that dereference second parameter..
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static std::set<std::string> functionNames2_all;
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static std::set<std::string> functionNames2_nullptr;
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if (functionNames2_all.empty()) {
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functionNames2_all.insert("memcmp");
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functionNames2_all.insert("memcpy");
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functionNames2_all.insert("memmove");
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functionNames2_all.insert("strcat");
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functionNames2_all.insert("strncat");
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functionNames2_all.insert("strcmp");
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functionNames2_all.insert("strncmp");
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functionNames2_all.insert("strcpy");
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functionNames2_all.insert("strncpy");
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functionNames2_all.insert("strstr");
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functionNames2_all.insert("sprintf");
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functionNames2_all.insert("fprintf");
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functionNames2_all.insert("fscanf");
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functionNames2_all.insert("sscanf");
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functionNames2_nullptr.insert("frexp");
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functionNames2_nullptr.insert("modf");
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}
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// 1st parameter..
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if ((Token::Match(&tok, "%var% ( %var% ,|)") && tok.tokAt(2)->varId() > 0) ||
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(value == 0 && Token::Match(&tok, "%var% ( 0 ,|)"))) {
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if (functionNames1_all.find(tok.str()) != functionNames1_all.end())
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var.push_back(tok.tokAt(2));
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else if (value == 0 && functionNames1_nullptr.find(tok.str()) != functionNames1_nullptr.end())
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var.push_back(tok.tokAt(2));
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else if (value != 0 && Token::simpleMatch(&tok, "fflush"))
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var.push_back(tok.tokAt(2));
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else if (value == 0 && Token::Match(&tok, "snprintf|vsnprintf|fnprintf|vfnprintf") && tok.strAt(4) != "0") // Only if length is not zero
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var.push_back(tok.tokAt(2));
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}
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// 2nd parameter..
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if (Token::Match(&tok, "%var% ( %any%")) {
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const Token* secondParameter = tok.tokAt(2)->nextArgument();
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if (secondParameter && ((value == 0 && secondParameter->str() == "0") || (Token::Match(secondParameter, "%var%") && secondParameter->varId() > 0))) {
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if (functionNames2_all.find(tok.str()) != functionNames2_all.end())
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var.push_back(secondParameter);
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else if (value == 0 && functionNames2_nullptr.find(tok.str()) != functionNames2_nullptr.end())
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var.push_back(secondParameter);
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}
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}
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if (Token::Match(&tok, "printf|sprintf|snprintf|fprintf|fnprintf|scanf|sscanf|fscanf")) {
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const Token* argListTok = 0; // Points to first va_list argument
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std::string formatString;
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bool scan = Token::Match(&tok, "scanf|sscanf|fscanf");
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if (Token::Match(&tok, "printf|scanf ( %str%")) {
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formatString = tok.strAt(2);
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if (tok.strAt(3) == ",")
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argListTok = tok.tokAt(4);
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else
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argListTok = 0;
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} else if (Token::Match(&tok, "sprintf|fprintf|sscanf|fscanf ( %any%")) {
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const Token* formatStringTok = tok.tokAt(2)->nextArgument(); // Find second parameter (format string)
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if (formatStringTok && Token::Match(formatStringTok, "%str%")) {
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argListTok = formatStringTok->nextArgument(); // Find third parameter (first argument of va_args)
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formatString = formatStringTok->str();
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}
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} else if (Token::Match(&tok, "snprintf|fnprintf ( %any%")) {
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const Token* formatStringTok = tok.tokAt(2);
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for (int i = 0; i < 2 && formatStringTok; i++) {
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formatStringTok = formatStringTok->nextArgument(); // Find third parameter (format string)
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}
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if (formatStringTok && Token::Match(formatStringTok, "%str%")) {
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argListTok = formatStringTok->nextArgument(); // Find fourth parameter (first argument of va_args)
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formatString = formatStringTok->str();
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}
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}
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if (argListTok) {
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bool percent = false;
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for (std::string::iterator i = formatString.begin(); i != formatString.end(); ++i) {
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if (*i == '%') {
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percent = !percent;
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} else if (percent) {
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percent = false;
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bool _continue = false;
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while (!std::isalpha(*i)) {
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if (*i == '*') {
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if (scan)
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_continue = true;
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else
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argListTok = argListTok->nextArgument();
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}
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++i;
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if (!argListTok || i == formatString.end())
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return;
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}
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if (_continue)
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continue;
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if ((*i == 'n' || *i == 's' || scan) && (!scan || value == 0)) {
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if ((value == 0 && argListTok->str() == "0") || (Token::Match(argListTok, "%var%") && argListTok->varId() > 0)) {
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var.push_back(argListTok);
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}
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}
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if (*i != 'm') // %m is a non-standard glibc extension that requires no parameter
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argListTok = argListTok->nextArgument(); // Find next argument
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if (!argListTok)
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break;
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}
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}
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}
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}
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}
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/**
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* Is there a pointer dereference? Everything that should result in
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* a nullpointer dereference error message will result in a true
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* return value. If it's unknown if the pointer is dereferenced false
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* is returned.
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* @param tok token for the pointer
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* @param unknown it is not known if there is a pointer dereference (could be reported as a debug message)
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* @return true => there is a dereference
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*/
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bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown)
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{
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const bool inconclusive = unknown;
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unknown = false;
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// Dereferencing pointer..
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if (Token::Match(tok->tokAt(-3), "!!sizeof [;{}=+-/(,] * %var%") && Token::Match(tok->tokAt(-3), "!!decltype [;{}=+-/(,] * %var%"))
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return true;
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// read/write member variable
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if (!Token::simpleMatch(tok->tokAt(-2), "& (") && !Token::Match(tok->tokAt(-2), "sizeof|decltype (") && tok->strAt(-1) != "&" && tok->strAt(-1) != "&&" && Token::Match(tok->next(), ". %var%")) {
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if (tok->strAt(3) != "(")
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return true;
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unknown = true;
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return false;
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}
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if (Token::Match(tok->previous(), "[;{}=+-/(,] %var% ["))
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return true;
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if (Token::Match(tok->previous(), "return %var% ["))
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return true;
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if (Token::Match(tok, "%var% ("))
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return true;
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if (Token::Match(tok, "%var% = %var% .") &&
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tok->varId() > 0 &&
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tok->varId() == tok->tokAt(2)->varId())
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return true;
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// Check if it's NOT a pointer dereference.
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// This is most useful in inconclusive checking
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if (inconclusive) {
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// Not a dereference..
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if (Token::Match(tok->previous(), "[;{}(] %var% ="))
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return false;
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// OK to delete a null
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if (Token::Match(tok->previous(), "delete %var%") || Token::Match(tok->tokAt(-3), "delete [ ] %var%"))
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return false;
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// OK to check if pointer is null
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// OK to take address of pointer
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if (Token::Match(tok->previous(), "!|& %var% )|,|&&|%oror%"))
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return false;
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// OK to pass pointer to function
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if (Token::Match(tok->previous(), "[(,] %var% [,)]"))
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return false;
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// Compare pointer
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if (Token::Match(tok->previous(), "(|&&|%oror%|==|!= %var% &&|%oror%|)"))
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return false;
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// Taking address
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if (Token::Match(tok->previous(), "return|= %var% ;"))
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return false;
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// unknown if it's a dereference
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// FIXME: Uncomment this. We just need to fix false positives
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// when cppcheck source code is checked before it can
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// be uncommented. We need to have better checks to
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// determine when there is NOT a pointer dereference.
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//unknown = true;
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}
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// assume that it's not a dereference (no false positives)
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return false;
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}
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// check if function can assign pointer
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bool CheckNullPointer::CanFunctionAssignPointer(const Token *functiontoken, unsigned int varid) const
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{
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if (Token::Match(functiontoken, "if|while|sizeof"))
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return false;
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int argumentNumber = 0;
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for (const Token *arg = functiontoken->tokAt(2); arg; arg = arg->nextArgument()) {
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++argumentNumber;
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if (Token::Match(arg, "%varid% [,)]", varid)) {
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const Token *ftok = _tokenizer->getFunctionTokenByName(functiontoken->str().c_str());
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if (!Token::Match(ftok, "%type% (")) {
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// assume that the function might assign the pointer
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return true;
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}
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ftok = ftok->tokAt(2);
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while (ftok && argumentNumber > 1) {
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ftok = ftok->nextArgument();
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--argumentNumber;
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}
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// check if it's a pointer parameter..
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while (ftok && ftok->isName())
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ftok = ftok->next();
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if (Token::Match(ftok, "* *| const| %var% [,)]"))
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// parameter is passed by value
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return false;
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}
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}
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// pointer is not passed
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return false;
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}
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void CheckNullPointer::nullPointerAfterLoop()
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{
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const SymbolDatabase* const symbolDatabase = _tokenizer->getSymbolDatabase();
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// Locate insufficient null-pointer handling after loop
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for (std::list<Scope>::const_iterator i = symbolDatabase->scopeList.begin(); i != symbolDatabase->scopeList.end(); ++i) {
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// only interested in while ( %var% )
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// TODO: Aren't there false negatives. Shouldn't other loops be handled such as:
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// - while ( ! %var% )
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const Token* const tok = i->classDef;
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if (i->type != Scope::eWhile || !Token::Match(tok, "while ( %var% )|&&"))
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continue;
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// Get variable id for the loop variable
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const Variable* var(symbolDatabase->getVariableFromVarId(tok->tokAt(2)->varId()));
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// Is variable a pointer?
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if (!var || !var->isPointer())
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continue;
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// Get variable name for the loop variable
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const std::string varname(tok->strAt(2));
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// Locate the end of the while loop body..
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const Token *tok2 = tok->next()->link()->next()->link();
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// Is this checking inconclusive?
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bool inconclusive = false;
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if (!tok2)
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continue;
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// Check if the variable is dereferenced after the while loop
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while (NULL != (tok2 = tok2->next())) {
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// inner and outer scopes
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if (tok2->str() == "{" || tok2->str() == "}") {
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// Not inconclusive: bail out
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if (!_settings->inconclusive)
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break;
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inconclusive = true;
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if (tok2->str() == "}") {
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// "}" => leaving function? then break.
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const Token *tok3 = tok2->link()->previous();
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if (!tok3 || !Token::Match(tok3, "[);]"))
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break;
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if (tok3->str() == ")" && !Token::Match(tok3->link()->previous(), "if|for|while"))
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break;
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}
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}
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// Stop checking if "break" is found
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else if (tok2->str() == "break")
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break;
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// loop variable is found..
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else if (tok2->varId() == var->varId()) {
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// dummy variable.. is it unknown if pointer is dereferenced or not?
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bool unknown = _settings->inconclusive;
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// Is the loop variable dereferenced?
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if (CheckNullPointer::isPointerDeRef(tok2, unknown)) {
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nullPointerError(tok2, varname, tok->linenr(), inconclusive);
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}
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else if (unknown && _settings->inconclusive) {
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nullPointerError(tok2, varname, tok->linenr(), true);
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}
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break;
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}
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}
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}
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}
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void CheckNullPointer::nullPointerLinkedList()
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{
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const SymbolDatabase* const symbolDatabase = _tokenizer->getSymbolDatabase();
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// looping through items in a linked list in a inner loop.
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// Here is an example:
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// for (const Token *tok = tokens; tok; tok = tok->next) {
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// if (tok->str() == "hello")
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// tok = tok->next; // <- tok might become a null pointer!
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// }
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for (std::list<Scope>::const_iterator i = symbolDatabase->scopeList.begin(); i != symbolDatabase->scopeList.end(); ++i) {
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const Token* const tok1 = i->classDef;
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// search for a "for" scope..
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if (i->type != Scope::eFor || !tok1)
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continue;
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// is there any dereferencing occurring in the for statement
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const Token* end2 = tok1->linkAt(1);
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for (const Token *tok2 = tok1->tokAt(2); tok2 != end2; tok2 = tok2->next()) {
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// Dereferencing a variable inside the "for" parentheses..
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if (Token::Match(tok2, "%var% . %var%")) {
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// Variable id for dereferenced variable
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const unsigned int varid(tok2->varId());
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if (varid == 0)
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continue;
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if (Token::Match(tok2->tokAt(-2), "%varid% ?", varid))
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continue;
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// Variable name of dereferenced variable
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const std::string varname(tok2->str());
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// Check usage of dereferenced variable in the loop..
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for (const Token *tok3 = i->classStart; tok3 && tok3 != i->classEnd; tok3 = tok3->next()) {
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// TODO: are there false negatives for "while ( %varid% ||"
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if (Token::Match(tok3, "while ( %varid% &&|)", varid)) {
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// Make sure there is a "break" or "return" inside the loop.
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// Without the "break" a null pointer could be dereferenced in the
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// for statement.
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// indentlevel4 is a counter for { and }. When scanning the code with tok4
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unsigned int indentlevel4 = 1;
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for (const Token *tok4 = tok3->next()->link(); tok4; tok4 = tok4->next()) {
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if (tok4->str() == "{")
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++indentlevel4;
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else if (tok4->str() == "}") {
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if (indentlevel4 <= 1) {
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const Variable* var = symbolDatabase->getVariableFromVarId(varid);
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// Is this variable a pointer?
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if (var && var->isPointer())
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nullPointerError(tok1, varname, tok3->linenr());
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break;
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}
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--indentlevel4;
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}
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// There is a "break" or "return" inside the loop.
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// TODO: there can be false negatives. There could still be
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// execution paths that are not properly terminated
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else if (tok4->str() == "break" || tok4->str() == "return")
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break;
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}
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}
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}
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}
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}
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}
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}
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void CheckNullPointer::nullPointerStructByDeRefAndChec()
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{
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// Dereferencing a struct pointer and then checking if it's NULL..
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// skipvar: don't check vars that has been tested against null already
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std::set<unsigned int> skipvar;
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skipvar.insert(0);
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// Scan through all tokens
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for (const Token *tok1 = _tokenizer->tokens(); tok1; tok1 = tok1->next()) {
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// Checking if some pointer is null.
|
|
// then add the pointer to skipvar => is it known that it isn't NULL
|
|
if (Token::Match(tok1, "if|while ( !| %var% )")) {
|
|
tok1 = tok1->tokAt(2);
|
|
if (tok1->str() == "!")
|
|
tok1 = tok1->next();
|
|
skipvar.insert(tok1->varId());
|
|
continue;
|
|
} else if (Token::Match(tok1, "( ! %var% ||") ||
|
|
Token::Match(tok1, "( %var% &&")) {
|
|
// TODO: there are false negatives caused by this. The
|
|
// variable should be removed from skipvar after the
|
|
// condition
|
|
tok1 = tok1->next();
|
|
if (tok1->str() == "!")
|
|
tok1 = tok1->next();
|
|
skipvar.insert(tok1->varId());
|
|
continue;
|
|
}
|
|
|
|
bool inconclusive = false;
|
|
|
|
/**
|
|
* @todo There are lots of false negatives here. A dereference
|
|
* is only investigated if a few specific conditions are met.
|
|
*/
|
|
|
|
// dereference in assignment
|
|
if (Token::Match(tok1, "[;{}] %var% . %var%")) {
|
|
tok1 = tok1->next();
|
|
if (tok1->strAt(3) == "(") {
|
|
if (!_settings->inconclusive)
|
|
continue;
|
|
inconclusive = true;
|
|
}
|
|
}
|
|
|
|
// dereference in assignment
|
|
else if (Token::Match(tok1, "[{};] %var% = %var% . %var%")) {
|
|
if (tok1->strAt(1) == tok1->strAt(3))
|
|
continue;
|
|
tok1 = tok1->tokAt(3);
|
|
}
|
|
|
|
// dereference in condition
|
|
else if (Token::Match(tok1, "if ( !| %var% .")) {
|
|
tok1 = tok1->tokAt(2);
|
|
if (tok1->str() == "!")
|
|
tok1 = tok1->next();
|
|
}
|
|
|
|
// dereference in function call (but not sizeof|decltype)
|
|
else if ((Token::Match(tok1->tokAt(-2), "%var% ( %var% . %var%") && !Token::Match(tok1->tokAt(-2), "sizeof|decltype ( %var% . %var%")) ||
|
|
Token::Match(tok1->previous(), ", %var% . %var%")) {
|
|
// Is the function return value taken by the pointer?
|
|
bool assignment = false;
|
|
const unsigned int varid1(tok1->varId());
|
|
if (varid1 == 0)
|
|
continue;
|
|
const Token *tok2 = tok1->previous();
|
|
while (tok2 && !Token::Match(tok2, "[;{}]")) {
|
|
if (Token::Match(tok2, "%varid% =", varid1)) {
|
|
assignment = true;
|
|
break;
|
|
}
|
|
tok2 = tok2->previous();
|
|
}
|
|
if (assignment)
|
|
continue;
|
|
|
|
// Is the dereference checked with a previous &&
|
|
bool checked = false;
|
|
for (tok2 = tok1->tokAt(-2); tok2; tok2 = tok2->previous()) {
|
|
if (Token::Match(tok2, "[,(;{}]"))
|
|
break;
|
|
else if (tok2->str() == ")")
|
|
tok2 = tok2->link();
|
|
else if (Token::Match(tok2, "%varid% &&", varid1)) {
|
|
checked = true;
|
|
break;
|
|
}
|
|
}
|
|
if (checked)
|
|
continue;
|
|
}
|
|
|
|
// Goto next token
|
|
else {
|
|
continue;
|
|
}
|
|
|
|
// struct dereference was found - investigate if it is later
|
|
// checked that it is not NULL
|
|
const unsigned int varid1(tok1->varId());
|
|
if (skipvar.find(varid1) != skipvar.end())
|
|
continue;
|
|
|
|
// name of struct pointer
|
|
const std::string varname(tok1->str());
|
|
|
|
// is pointer local?
|
|
bool isLocal = false;
|
|
const Variable * var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(tok1->varId());
|
|
if (!var)
|
|
continue;
|
|
if (var->isLocal() || var->isArgument())
|
|
isLocal = true;
|
|
|
|
// member function may or may not nullify the pointer if it's global (#2647)
|
|
if (!isLocal) {
|
|
const Token *tok2 = tok1;
|
|
while (Token::Match(tok2, "%var% ."))
|
|
tok2 = tok2->tokAt(2);
|
|
if (Token::Match(tok2,"%var% ("))
|
|
continue;
|
|
}
|
|
|
|
// count { and } using tok2
|
|
unsigned int indentlevel2 = 0;
|
|
for (const Token *tok2 = tok1->tokAt(3); tok2; tok2 = tok2->next()) {
|
|
if (tok2->str() == "{")
|
|
++indentlevel2;
|
|
|
|
else if (tok2->str() == "}") {
|
|
if (indentlevel2 == 0)
|
|
break;
|
|
--indentlevel2;
|
|
}
|
|
|
|
// label / ?:
|
|
else if (tok2->str() == ":")
|
|
break;
|
|
|
|
// function call..
|
|
else if (Token::Match(tok2, "[;{}] %var% (") && CanFunctionAssignPointer(tok2->next(), varid1)) {
|
|
if (!_settings->inconclusive)
|
|
break;
|
|
inconclusive = true;
|
|
}
|
|
|
|
// Reassignment of the struct
|
|
else if (tok2->varId() == varid1) {
|
|
if (tok2->next()->str() == "=") {
|
|
// Avoid false positives when there is 'else if'
|
|
// TODO: can this be handled better?
|
|
if (tok1->strAt(-2) == "if")
|
|
skipvar.insert(varid1);
|
|
break;
|
|
}
|
|
if (Token::Match(tok2->tokAt(-2), "[,(] &"))
|
|
break;
|
|
}
|
|
|
|
// Loop..
|
|
/** @todo don't bail out if the variable is not used in the loop */
|
|
else if (tok2->str() == "do")
|
|
break;
|
|
|
|
// return/break at base level => stop checking
|
|
else if (indentlevel2 == 0 && (tok2->str() == "return" || tok2->str() == "break"))
|
|
break;
|
|
|
|
// Function call: If the pointer is not a local variable it
|
|
// might be changed by the call.
|
|
else if (Token::Match(tok2, "[;{}] %var% (") &&
|
|
Token::simpleMatch(tok2->linkAt(2), ") ;") && !isLocal) {
|
|
break;
|
|
}
|
|
|
|
// Check if pointer is null.
|
|
// TODO: false negatives for "if (!p || .."
|
|
else if (!tok2->isExpandedMacro() && Token::Match(tok2, "if ( !| %varid% )|&&", varid1)) {
|
|
// Is this variable a pointer?
|
|
if (var->isPointer())
|
|
nullPointerError(tok1, varname, tok2->linenr(), inconclusive);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckNullPointer::nullPointerByDeRefAndChec()
|
|
{
|
|
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
|
|
|
|
// Dereferencing a pointer and then checking if it's NULL..
|
|
// This check will first scan for the check. And then scan backwards
|
|
// from the check, searching for dereferencing.
|
|
for (std::list<Scope>::const_iterator i = symbolDatabase->scopeList.begin(); i != symbolDatabase->scopeList.end(); ++i) {
|
|
// TODO: false negatives.
|
|
// - logical operators
|
|
// - while
|
|
const Token* const tok = i->classDef;
|
|
if (i->type == Scope::eIf && tok && !tok->isExpandedMacro() && Token::Match(tok->previous(), "; if ( !| %var% )|%oror%|&&")) {
|
|
const Token * vartok = tok->tokAt(2);
|
|
if (vartok->str() == "!")
|
|
vartok = vartok->next();
|
|
|
|
// Variable id for pointer
|
|
const unsigned int varid(vartok->varId());
|
|
if (varid == 0)
|
|
continue;
|
|
|
|
// Name of pointer
|
|
const std::string varname(vartok->str());
|
|
|
|
const Variable* var = symbolDatabase->getVariableFromVarId(varid);
|
|
// Check that variable is a pointer..
|
|
if (!var || !var->isPointer())
|
|
continue;
|
|
|
|
const Token * const decltok = var->nameToken();
|
|
bool inconclusive = false;
|
|
|
|
for (const Token *tok1 = tok->previous(); tok1 && tok1 != decltok; tok1 = tok1->previous()) {
|
|
if (tok1->str() == ")" && Token::Match(tok1->link()->previous(), "%var% (")) {
|
|
const Token *tok2 = tok1->link();
|
|
while (tok2 && !Token::Match(tok2, "[;{}?:]"))
|
|
tok2 = tok2->previous();
|
|
if (Token::Match(tok2, "[?:]"))
|
|
break;
|
|
if (Token::Match(tok2, "[;{}] %varid% = %var%", varid))
|
|
break;
|
|
|
|
if (Token::Match(tok1->link()->previous(), "while ( %varid%", varid))
|
|
break;
|
|
|
|
if (Token::Match(tok1->link(), "( ! %varid% ||", varid) ||
|
|
Token::Match(tok1->link(), "( %varid% &&", varid)) {
|
|
tok1 = tok1->link();
|
|
continue;
|
|
}
|
|
|
|
if (Token::simpleMatch(tok1->link()->previous(), "sizeof (")) {
|
|
tok1 = tok1->link()->previous();
|
|
continue;
|
|
}
|
|
|
|
if (Token::Match(tok2, "[;{}] %var% ( %varid% ,", varid)) {
|
|
std::list<const Token *> varlist;
|
|
parseFunctionCall(*(tok2->next()), varlist, 0);
|
|
if (!varlist.empty() && varlist.front() == tok2->tokAt(3)) {
|
|
nullPointerError(tok2->tokAt(3), varname, tok->linenr(), inconclusive);
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Passing pointer as parameter..
|
|
if (Token::Match(tok2, "[;{}] %type% (")) {
|
|
if (CanFunctionAssignPointer(tok2->next(), varid)) {
|
|
if (!_settings->inconclusive)
|
|
break;
|
|
inconclusive = true;
|
|
}
|
|
}
|
|
|
|
// calling unknown function => it might initialize the pointer
|
|
if (!(var->isLocal() || var->isArgument()))
|
|
break;
|
|
}
|
|
|
|
if (tok1->str() == "break")
|
|
break;
|
|
|
|
if (tok1->varId() == varid) {
|
|
// Don't write warning if the dereferencing is
|
|
// guarded by ?: or &&
|
|
const Token *tok2 = tok1->previous();
|
|
if (tok2 && (tok2->isArithmeticalOp() || tok2->str() == "(")) {
|
|
while (tok2 && !Token::Match(tok2, "[;{}?:]")) {
|
|
if (tok2->str() == ")")
|
|
tok2 = tok2->link();
|
|
// guarded by &&
|
|
if (tok2->varId() == varid && tok2->next()->str() == "&&")
|
|
break;
|
|
tok2 = tok2->previous();
|
|
}
|
|
}
|
|
if (Token::Match(tok2, "[?:]") || tok2->varId() == varid)
|
|
continue;
|
|
|
|
// unknown : this is set by isPointerDeRef if it is
|
|
// uncertain
|
|
bool unknown = false;
|
|
|
|
if (Token::Match(tok1->tokAt(-2), "%varid% = %varid% .", varid)) {
|
|
break;
|
|
} else if (Token::simpleMatch(tok1->tokAt(-2), "* )") &&
|
|
Token::Match(tok1->linkAt(-1)->tokAt(-2), "%varid% = (", tok1->varId())) {
|
|
break;
|
|
} else if (Token::simpleMatch(tok1->tokAt(-3), "* ) (") &&
|
|
Token::Match(tok1->linkAt(-2)->tokAt(-2), "%varid% = (", tok1->varId())) {
|
|
break;
|
|
} else if (Token::Match(tok1->previous(), "&&|%oror%")) {
|
|
break;
|
|
} else if (Token::Match(tok1->tokAt(-2), "&&|%oror% !")) {
|
|
break;
|
|
} else if (CheckNullPointer::isPointerDeRef(tok1, unknown)) {
|
|
nullPointerError(tok1, varname, tok->linenr(), inconclusive);
|
|
break;
|
|
} else if (Token::simpleMatch(tok1->previous(), "&")) {
|
|
break;
|
|
} else if (Token::simpleMatch(tok1->next(), "=")) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
else if (tok1->str() == "{" ||
|
|
tok1->str() == "}")
|
|
break;
|
|
|
|
// label..
|
|
else if (Token::Match(tok1, "%type% :"))
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckNullPointer::nullPointerByCheckAndDeRef()
|
|
{
|
|
// Check if pointer is NULL and then dereference it..
|
|
|
|
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
|
|
if (Token::simpleMatch(tok, "if (") && !tok->isExpandedMacro()) {
|
|
// TODO: investigate false negatives:
|
|
// - handle "while"?
|
|
// - if there are logical operators
|
|
// - if (x) { } else { ... }
|
|
|
|
// If the if-body ends with a unknown macro then bailout
|
|
{
|
|
// goto the end parenthesis
|
|
const Token *endpar = tok->next()->link();
|
|
const Token *endbody = Token::simpleMatch(endpar, ") {") ? endpar->next()->link() : 0;
|
|
if (endbody &&
|
|
Token::Match(endbody->tokAt(-3), "[;{}] %var% ;") &&
|
|
isUpper(endbody->strAt(-2)))
|
|
continue;
|
|
}
|
|
|
|
// vartok : token for the variable
|
|
const Token *vartok = 0;
|
|
if (Token::Match(tok, "if ( ! %var% )|&&"))
|
|
vartok = tok->tokAt(3);
|
|
else if (Token::Match(tok, "if|while ( %var% )|&&"))
|
|
vartok = tok->tokAt(2);
|
|
else if (Token::Match(tok, "if ( ! ( %var% ="))
|
|
vartok = tok->tokAt(4);
|
|
else
|
|
continue;
|
|
|
|
// variable id for pointer
|
|
const unsigned int varid(vartok->varId());
|
|
if (varid == 0)
|
|
continue;
|
|
|
|
const unsigned int linenr = vartok->linenr();
|
|
|
|
const Variable* var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(varid);
|
|
// Check if variable is a pointer
|
|
if (!var || !var->isPointer())
|
|
continue;
|
|
|
|
if (Token::Match(vartok->next(), "&& ( %varid% =", varid))
|
|
continue;
|
|
|
|
// if this is true then it is known that the pointer is null
|
|
bool null = true;
|
|
|
|
// start token = inside the if-body
|
|
const Token *tok1 = tok->next()->link()->tokAt(2);
|
|
|
|
// indentlevel inside the if-body is 1
|
|
unsigned int indentlevel = 1;
|
|
|
|
if (Token::Match(tok, "if|while ( %var% )|&&")) {
|
|
// pointer might be null
|
|
null = false;
|
|
|
|
// start token = first token after the if/while body
|
|
tok1 = tok1->previous()->link();
|
|
tok1 = tok1 ? tok1->next() : NULL;
|
|
if (!tok1)
|
|
continue;
|
|
|
|
// indentlevel at the base level is 0
|
|
indentlevel = 0;
|
|
}
|
|
|
|
// Name of the pointer
|
|
const std::string &pointerName = vartok->str();
|
|
|
|
// Set to true if we would normally bail out the check.
|
|
bool inconclusive = false;
|
|
|
|
// Count { and } for tok2
|
|
for (const Token *tok2 = tok1; tok2; tok2 = tok2->next()) {
|
|
if (tok2->str() == "{")
|
|
++indentlevel;
|
|
else if (tok2->str() == "}") {
|
|
if (indentlevel == 0)
|
|
break;
|
|
--indentlevel;
|
|
|
|
// calling exit function?
|
|
bool unknown = false;
|
|
if (_tokenizer->IsScopeNoReturn(tok2, &unknown)) {
|
|
if (_settings->inconclusive && unknown)
|
|
inconclusive = true;
|
|
else
|
|
break;
|
|
}
|
|
|
|
if (null && indentlevel == 0) {
|
|
// skip all "else" blocks because they are not executed in this execution path
|
|
while (Token::simpleMatch(tok2, "} else {"))
|
|
tok2 = tok2->linkAt(2);
|
|
null = false;
|
|
}
|
|
}
|
|
|
|
if (Token::Match(tok2, "goto|return|continue|break|throw|if|switch|for")) {
|
|
bool dummy = false;
|
|
if (Token::Match(tok2, "return * %varid%", varid))
|
|
nullPointerError(tok2, pointerName, linenr, inconclusive);
|
|
else if (Token::Match(tok2, "return %varid%", varid) &&
|
|
CheckNullPointer::isPointerDeRef(tok2->next(), dummy))
|
|
nullPointerError(tok2, pointerName, linenr, inconclusive);
|
|
break;
|
|
}
|
|
|
|
// parameters to sizeof are not dereferenced
|
|
if (Token::Match(tok2, "decltype|sizeof")) {
|
|
if (tok2->strAt(1) != "(")
|
|
break;
|
|
|
|
tok2 = tok2->next()->link();
|
|
continue;
|
|
}
|
|
|
|
// function call, check if pointer is dereferenced
|
|
if (Token::Match(tok2, "%var% (")) {
|
|
std::list<const Token *> vars;
|
|
parseFunctionCall(*tok2, vars, 0);
|
|
for (std::list<const Token *>::const_iterator it = vars.begin(); it != vars.end(); ++it) {
|
|
if (Token::Match(*it, "%varid% [,)]", varid)) {
|
|
nullPointerError(*it, pointerName, linenr, inconclusive);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// calling unknown function (abort/init)..
|
|
if (Token::simpleMatch(tok2, ") ;") &&
|
|
(Token::Match(tok2->link()->tokAt(-2), "[;{}.] %var% (") ||
|
|
Token::Match(tok2->link()->tokAt(-5), "[;{}] ( * %var% ) ("))) {
|
|
// noreturn function?
|
|
bool unknown = false;
|
|
if (_tokenizer->IsScopeNoReturn(tok2->tokAt(2), &unknown)) {
|
|
if (!unknown || !_settings->inconclusive) {
|
|
break;
|
|
}
|
|
inconclusive = true;
|
|
}
|
|
|
|
// init function (global variables)
|
|
if (!var || !(var->isLocal() || var->isArgument()))
|
|
break;
|
|
}
|
|
|
|
if (tok2->varId() == varid) {
|
|
// unknown: this is set to true by isPointerDeRef if
|
|
// the function fails to determine if there
|
|
// is a dereference or not
|
|
bool unknown = _settings->inconclusive;
|
|
|
|
if (Token::Match(tok2->previous(), "[;{}=] %var% = 0 ;"))
|
|
;
|
|
|
|
else if (CheckNullPointer::isPointerDeRef(tok2, unknown))
|
|
nullPointerError(tok2, pointerName, linenr, inconclusive);
|
|
|
|
else if (unknown && _settings->inconclusive)
|
|
nullPointerError(tok2, pointerName, linenr, true);
|
|
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
void CheckNullPointer::nullPointer()
|
|
{
|
|
nullPointerAfterLoop();
|
|
nullPointerLinkedList();
|
|
nullPointerStructByDeRefAndChec();
|
|
nullPointerByDeRefAndChec();
|
|
nullPointerByCheckAndDeRef();
|
|
}
|
|
|
|
/** Dereferencing null constant (simplified token list) */
|
|
void CheckNullPointer::nullConstantDereference()
|
|
{
|
|
// this is kept at 0 for all scopes that are not executing
|
|
unsigned int indentlevel = 0;
|
|
|
|
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
|
|
// start of executable scope..
|
|
if (indentlevel == 0 && Token::Match(tok, ") const| {"))
|
|
indentlevel = 1;
|
|
|
|
else if (indentlevel >= 1) {
|
|
if (tok->str() == "{")
|
|
++indentlevel;
|
|
|
|
else if (tok->str() == "}") {
|
|
if (indentlevel <= 2)
|
|
indentlevel = 0;
|
|
else
|
|
--indentlevel;
|
|
}
|
|
|
|
if (tok->str() == "(" && Token::Match(tok->previous(), "sizeof|decltype|typeid"))
|
|
tok = tok->link();
|
|
|
|
else if (Token::simpleMatch(tok, "* 0")) {
|
|
if (Token::Match(tok->previous(), "return|;|{|}|=|(|,|%op%")) {
|
|
nullPointerError(tok);
|
|
}
|
|
}
|
|
|
|
else if (indentlevel > 0 && Token::Match(tok->previous(), "[={};] %var% (")) {
|
|
std::list<const Token *> var;
|
|
parseFunctionCall(*tok, var, 0);
|
|
|
|
// is one of the var items a NULL pointer?
|
|
for (std::list<const Token *>::const_iterator it = var.begin(); it != var.end(); ++it) {
|
|
if (Token::Match(*it, "0 [,)]")) {
|
|
nullPointerError(*it);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/// @addtogroup Checks
|
|
/// @{
|
|
|
|
|
|
/**
|
|
* @brief %Check for null pointer usage (using ExecutionPath)
|
|
*/
|
|
|
|
class Nullpointer : public ExecutionPath {
|
|
public:
|
|
/** Startup constructor */
|
|
explicit Nullpointer(Check *c) : ExecutionPath(c, 0), null(false) {
|
|
}
|
|
|
|
private:
|
|
/** Create checking of specific variable: */
|
|
Nullpointer(Check *c, const unsigned int id, const std::string &name)
|
|
: ExecutionPath(c, id),
|
|
varname(name),
|
|
null(false) {
|
|
}
|
|
|
|
/** Copy this check */
|
|
ExecutionPath *copy() {
|
|
return new Nullpointer(*this);
|
|
}
|
|
|
|
/** no implementation => compiler error if used by accident */
|
|
void operator=(const Nullpointer &);
|
|
|
|
/** is other execution path equal? */
|
|
bool is_equal(const ExecutionPath *e) const {
|
|
const Nullpointer *c = static_cast<const Nullpointer *>(e);
|
|
return (varname == c->varname && null == c->null);
|
|
}
|
|
|
|
/** variable name for this check (empty => dummy check) */
|
|
const std::string varname;
|
|
|
|
/** is this variable null? */
|
|
bool null;
|
|
|
|
/** variable is set to null */
|
|
static void setnull(std::list<ExecutionPath *> &checks, const unsigned int varid) {
|
|
std::list<ExecutionPath *>::iterator it;
|
|
for (it = checks.begin(); it != checks.end(); ++it) {
|
|
Nullpointer *c = dynamic_cast<Nullpointer *>(*it);
|
|
if (c && c->varId == varid)
|
|
c->null = true;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Dereferencing variable. Check if it is safe (if the variable is null there's an error)
|
|
* @param checks Checks
|
|
* @param tok token where dereferencing happens
|
|
*/
|
|
static void dereference(std::list<ExecutionPath *> &checks, const Token *tok) {
|
|
const unsigned int varid(tok->varId());
|
|
|
|
std::list<ExecutionPath *>::iterator it;
|
|
for (it = checks.begin(); it != checks.end(); ++it) {
|
|
Nullpointer *c = dynamic_cast<Nullpointer *>(*it);
|
|
if (c && c->varId == varid && c->null) {
|
|
CheckNullPointer *checkNullPointer = dynamic_cast<CheckNullPointer *>(c->owner);
|
|
if (checkNullPointer) {
|
|
checkNullPointer->nullPointerError(tok, c->varname);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/** parse tokens */
|
|
const Token *parse(const Token &tok, std::list<ExecutionPath *> &checks) const {
|
|
if (Token::Match(tok.previous(), "[;{}] const| struct| %type% * %var% ;")) {
|
|
const Token * vartok = tok.tokAt(2);
|
|
|
|
if (tok.str() == "const")
|
|
vartok = vartok->next();
|
|
|
|
if (tok.str() == "struct")
|
|
vartok = vartok->next();
|
|
|
|
if (vartok->varId() != 0)
|
|
checks.push_back(new Nullpointer(owner, vartok->varId(), vartok->str()));
|
|
return vartok->next();
|
|
}
|
|
|
|
// Template pointer variable..
|
|
if (Token::Match(tok.previous(), "[;{}] %type% ::|<")) {
|
|
const Token * vartok = &tok;
|
|
while (Token::Match(vartok, "%type% ::"))
|
|
vartok = vartok->tokAt(2);
|
|
if (Token::Match(vartok, "%type% < %type%")) {
|
|
vartok = vartok->tokAt(3);
|
|
while (vartok && (vartok->str() == "*" || vartok->isName()))
|
|
vartok = vartok->next();
|
|
}
|
|
if (vartok
|
|
&& (vartok->str() == ">" || vartok->isName())
|
|
&& Token::Match(vartok->next(), "* %var% ;|=")) {
|
|
vartok = vartok->tokAt(2);
|
|
checks.push_back(new Nullpointer(owner, vartok->varId(), vartok->str()));
|
|
if (Token::simpleMatch(vartok->next(), "= 0 ;"))
|
|
setnull(checks, vartok->varId());
|
|
return vartok->next();
|
|
}
|
|
}
|
|
|
|
if (Token::simpleMatch(&tok, "try {")) {
|
|
// Bail out all used variables
|
|
unsigned int indentlevel = 0;
|
|
for (const Token *tok2 = &tok; tok2; tok2 = tok2->next()) {
|
|
if (tok2->str() == "{")
|
|
++indentlevel;
|
|
else if (tok2->str() == "}") {
|
|
if (indentlevel == 0)
|
|
break;
|
|
if (indentlevel == 1 && !Token::simpleMatch(tok2,"} catch ("))
|
|
return tok2;
|
|
--indentlevel;
|
|
} else if (tok2->varId())
|
|
bailOutVar(checks,tok2->varId());
|
|
}
|
|
}
|
|
|
|
if (Token::Match(&tok, "%var% (")) {
|
|
if (tok.str() == "sizeof" || tok.str() == "typeid")
|
|
return tok.next()->link();
|
|
|
|
// parse usage..
|
|
std::list<const Token *> var;
|
|
CheckNullPointer::parseFunctionCall(tok, var, 0);
|
|
for (std::list<const Token *>::const_iterator it = var.begin(); it != var.end(); ++it)
|
|
dereference(checks, *it);
|
|
}
|
|
|
|
else if (Token::simpleMatch(&tok, "( 0 &&"))
|
|
return tok.link();
|
|
|
|
if (tok.varId() != 0) {
|
|
// unknown : not really used. it is passed to isPointerDeRef.
|
|
// if isPointerDeRef fails to determine if there
|
|
// is a dereference the this will be set to true.
|
|
bool unknown = owner->inconclusiveFlag();
|
|
|
|
if (Token::Match(tok.previous(), "[;{}=] %var% = 0 ;"))
|
|
setnull(checks, tok.varId());
|
|
else if (CheckNullPointer::isPointerDeRef(&tok, unknown))
|
|
dereference(checks, &tok);
|
|
else if (unknown && owner->inconclusiveFlag())
|
|
dereference(checks, &tok);
|
|
else
|
|
// TODO: Report debug warning that it's unknown if a
|
|
// pointer is dereferenced
|
|
bailOutVar(checks, tok.varId());
|
|
}
|
|
|
|
else if (tok.str() == "delete") {
|
|
const Token *ret = tok.next();
|
|
if (Token::simpleMatch(ret, "[ ]"))
|
|
ret = ret->tokAt(2);
|
|
if (Token::Match(ret, "%var% ;"))
|
|
return ret->next();
|
|
}
|
|
|
|
else if (tok.str() == "return") {
|
|
bool unknown = false;
|
|
const Token *vartok = tok.next();
|
|
if (vartok->str() == "*")
|
|
vartok = vartok->next();
|
|
if (vartok->varId() && CheckNullPointer::isPointerDeRef(vartok, unknown)) {
|
|
dereference(checks, vartok);
|
|
}
|
|
}
|
|
|
|
return &tok;
|
|
}
|
|
|
|
/** parse condition. @sa ExecutionPath::parseCondition */
|
|
bool parseCondition(const Token &tok, std::list<ExecutionPath *> &checks) {
|
|
for (const Token *tok2 = &tok; tok2; tok2 = tok2->next()) {
|
|
if (tok2->str() == "(" || tok2->str() == ")")
|
|
break;
|
|
if (Token::Match(tok2, "[<>=] * %var%"))
|
|
dereference(checks, tok2->tokAt(2));
|
|
}
|
|
|
|
if (Token::Match(&tok, "!| %var% (")) {
|
|
std::list<const Token *> var;
|
|
CheckNullPointer::parseFunctionCall(tok.str() == "!" ? *tok.next() : tok, var, 0);
|
|
for (std::list<const Token *>::const_iterator it = var.begin(); it != var.end(); ++it)
|
|
dereference(checks, *it);
|
|
}
|
|
|
|
return ExecutionPath::parseCondition(tok, checks);
|
|
}
|
|
|
|
|
|
void parseLoopBody(const Token *tok, std::list<ExecutionPath *> &checks) const {
|
|
while (tok) {
|
|
if (Token::Match(tok, "{|}|return|goto|break|if"))
|
|
return;
|
|
const Token *next = parse(*tok, checks);
|
|
if (next)
|
|
tok = tok->next();
|
|
}
|
|
}
|
|
|
|
};
|
|
/// @}
|
|
|
|
|
|
void CheckNullPointer::executionPaths()
|
|
{
|
|
// Check for null pointer errors..
|
|
Nullpointer c(this);
|
|
checkExecutionPaths(_tokenizer->tokens(), &c);
|
|
}
|
|
|
|
void CheckNullPointer::nullPointerError(const Token *tok)
|
|
{
|
|
reportError(tok, Severity::error, "nullPointer", "Null pointer dereference");
|
|
}
|
|
|
|
void CheckNullPointer::nullPointerError(const Token *tok, const std::string &varname)
|
|
{
|
|
reportError(tok, Severity::error, "nullPointer", "Possible null pointer dereference: " + varname);
|
|
}
|
|
|
|
void CheckNullPointer::nullPointerError(const Token *tok, const std::string &varname, const unsigned int line, bool inconclusive)
|
|
{
|
|
const std::string errmsg("Possible null pointer dereference: " + varname + " - otherwise it is redundant to check if " + varname + " is null at line " + MathLib::toString<unsigned int>(line));
|
|
if (inconclusive)
|
|
reportInconclusiveError(tok, Severity::error, "nullPointer", errmsg);
|
|
else
|
|
reportError(tok, Severity::error, "nullPointer", errmsg);
|
|
}
|
|
|
|
|
|
|