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checkcondition.cpp
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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2024 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
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* 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 <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
// Check for condition mismatches
//---------------------------------------------------------------------------
#include "checkcondition.h"
#include "astutils.h"
#include "library.h"
#include "platform.h"
#include "settings.h"
#include "symboldatabase.h"
#include "token.h"
#include "tokenize.h"
#include "utils.h"
#include "vfvalue.h"
#include "checkother.h" // comparisonNonZeroExpressionLessThanZero and testIfNonZeroExpressionIsPositive
#include <algorithm>
#include <cstdint>
#include <limits>
#include <list>
#include <set>
#include <sstream>
#include <utility>
#include <vector>
// CWE ids used
static const CWE uncheckedErrorConditionCWE(391U);
static const CWE CWE398(398U); // Indicator of Poor Code Quality
static const CWE CWE570(570U); // Expression is Always False
static const CWE CWE571(571U); // Expression is Always True
//---------------------------------------------------------------------------
// Register this check class (by creating a static instance of it)
namespace {
CheckCondition instance;
}
bool CheckCondition::diag(const Token* tok, bool insert)
{
if (!tok)
return false;
const Token* parent = tok->astParent();
bool hasParent = false;
while (Token::Match(parent, "!|&&|%oror%")) {
if (mCondDiags.count(parent) != 0) {
hasParent = true;
break;
}
parent = parent->astParent();
}
if (mCondDiags.count(tok) == 0 && !hasParent) {
if (insert)
mCondDiags.insert(tok);
return false;
}
return true;
}
bool CheckCondition::isAliased(const std::set<int> &vars) const
{
for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
if (Token::Match(tok, "= & %var% ;") && vars.find(tok->tokAt(2)->varId()) != vars.end())
return true;
}
return false;
}
void CheckCondition::assignIf()
{
if (!mSettings->severity.isEnabled(Severity::style) && !mSettings->isPremiumEnabled("assignIfError"))
return;
logChecker("CheckCondition::assignIf"); // style
for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
if (tok->str() != "=")
continue;
if (Token::Match(tok->tokAt(-2), "[;{}] %var% =")) {
const Variable *var = tok->previous()->variable();
if (var == nullptr)
continue;
char bitop = '\0';
MathLib::bigint num = 0;
if (Token::Match(tok->next(), "%num% [&|]")) {
bitop = tok->strAt(2).at(0);
num = MathLib::toBigNumber(tok->tokAt(1));
} else {
const Token *endToken = Token::findsimplematch(tok, ";");
// Casting address
if (endToken && Token::Match(endToken->tokAt(-4), "* ) & %any% ;"))
endToken = nullptr;
if (endToken && Token::Match(endToken->tokAt(-2), "[&|] %num% ;")) {
bitop = endToken->strAt(-2).at(0);
num = MathLib::toBigNumber(endToken->tokAt(-1));
}
}
if (bitop == '\0')
continue;
if (num < 0 && bitop == '|')
continue;
assignIfParseScope(tok, tok->tokAt(4), var->declarationId(), var->isLocal(), bitop, num);
}
}
}
static bool isParameterChanged(const Token *partok)
{
bool addressOf = Token::Match(partok, "[(,] &");
int argumentNumber = 0;
const Token *ftok;
for (ftok = partok; ftok && ftok->str() != "("; ftok = ftok->previous()) {
if (ftok->str() == ")")
ftok = ftok->link();
else if (argumentNumber == 0U && ftok->str() == "&")
addressOf = true;
else if (ftok->str() == ",")
argumentNumber++;
}
ftok = ftok ? ftok->previous() : nullptr;
if (!(ftok && ftok->function()))
return true;
const Variable *par = ftok->function()->getArgumentVar(argumentNumber);
if (!par)
return true;
if (par->isConst())
return false;
if (addressOf || par->isReference() || par->isPointer())
return true;
return false;
}
/** parse scopes recursively */
bool CheckCondition::assignIfParseScope(const Token * const assignTok,
const Token * const startTok,
const nonneg int varid,
const bool islocal,
const char bitop,
const MathLib::bigint num)
{
bool ret = false;
for (const Token *tok2 = startTok; tok2; tok2 = tok2->next()) {
if ((bitop == '&') && Token::Match(tok2->tokAt(2), "%varid% %cop% %num% ;", varid) && tok2->strAt(3) == std::string(1U, bitop)) {
const MathLib::bigint num2 = MathLib::toBigNumber(tok2->tokAt(4));
if (0 == (num & num2))
mismatchingBitAndError(assignTok, num, tok2, num2);
}
if (Token::Match(tok2, "%varid% =", varid)) {
return true;
}
if (bitop == '&' && Token::Match(tok2, "%varid% &= %num% ;", varid)) {
const MathLib::bigint num2 = MathLib::toBigNumber(tok2->tokAt(2));
if (0 == (num & num2))
mismatchingBitAndError(assignTok, num, tok2, num2);
}
if (Token::Match(tok2, "++|-- %varid%", varid) || Token::Match(tok2, "%varid% ++|--", varid))
return true;
if (Token::Match(tok2, "[(,] &| %varid% [,)]", varid) && isParameterChanged(tok2))
return true;
if (tok2->str() == "}")
return false;
if (Token::Match(tok2, "break|continue|return"))
ret = true;
if (ret && tok2->str() == ";")
return false;
if (!islocal && Token::Match(tok2, "%name% (") && !Token::simpleMatch(tok2->linkAt(1), ") {"))
return true;
if (Token::Match(tok2, "if|while (")) {
if (!islocal && tok2->str() == "while")
continue;
if (tok2->str() == "while") {
// is variable changed in loop?
const Token *bodyStart = tok2->linkAt(1)->next();
const Token *bodyEnd = bodyStart ? bodyStart->link() : nullptr;
if (!bodyEnd || bodyEnd->str() != "}" || isVariableChanged(bodyStart, bodyEnd, varid, !islocal, *mSettings))
continue;
}
// parse condition
const Token * const end = tok2->linkAt(1);
for (; tok2 != end; tok2 = tok2->next()) {
if (Token::Match(tok2, "[(,] &| %varid% [,)]", varid)) {
return true;
}
if (Token::Match(tok2,"&&|%oror%|( %varid% ==|!= %num% &&|%oror%|)", varid)) {
const Token *vartok = tok2->next();
const MathLib::bigint num2 = MathLib::toBigNumber(vartok->tokAt(2));
if ((num & num2) != ((bitop=='&') ? num2 : num)) {
const std::string& op(vartok->strAt(1));
const bool alwaysTrue = op == "!=";
const std::string condition(vartok->str() + op + vartok->strAt(2));
assignIfError(assignTok, tok2, condition, alwaysTrue);
}
}
if (Token::Match(tok2, "%varid% %op%", varid) && tok2->next()->isAssignmentOp()) {
return true;
}
}
const bool ret1 = assignIfParseScope(assignTok, end->tokAt(2), varid, islocal, bitop, num);
bool ret2 = false;
if (Token::simpleMatch(end->linkAt(1), "} else {"))
ret2 = assignIfParseScope(assignTok, end->linkAt(1)->tokAt(3), varid, islocal, bitop, num);
if (ret1 || ret2)
return true;
}
}
return false;
}
void CheckCondition::assignIfError(const Token *tok1, const Token *tok2, const std::string &condition, bool result)
{
if (tok2 && diag(tok2->tokAt(2)))
return;
std::list<const Token *> locations = { tok1, tok2 };
reportError(locations,
Severity::style,
"assignIfError",
"Mismatching assignment and comparison, comparison '" + condition + "' is always " + std::string(bool_to_string(result)) + ".", CWE398, Certainty::normal);
}
void CheckCondition::mismatchingBitAndError(const Token *tok1, const MathLib::bigint num1, const Token *tok2, const MathLib::bigint num2)
{
std::list<const Token *> locations = { tok1, tok2 };
std::ostringstream msg;
msg << "Mismatching bitmasks. Result is always 0 ("
<< "X = Y & 0x" << std::hex << num1 << "; Z = X & 0x" << std::hex << num2 << "; => Z=0).";
reportError(locations,
Severity::style,
"mismatchingBitAnd",
msg.str(), CWE398, Certainty::normal);
}
static void getnumchildren(const Token *tok, std::list<MathLib::bigint> &numchildren)
{
if (tok->astOperand1() && tok->astOperand1()->isNumber())
numchildren.push_back(MathLib::toBigNumber(tok->astOperand1()));
else if (tok->astOperand1() && tok->str() == tok->astOperand1()->str())
getnumchildren(tok->astOperand1(), numchildren);
if (tok->astOperand2() && tok->astOperand2()->isNumber())
numchildren.push_back(MathLib::toBigNumber(tok->astOperand2()));
else if (tok->astOperand2() && tok->str() == tok->astOperand2()->str())
getnumchildren(tok->astOperand2(), numchildren);
}
/* Return whether tok is in the body for a function returning a boolean. */
static bool inBooleanFunction(const Token *tok)
{
const Scope *scope = tok ? tok->scope() : nullptr;
while (scope && scope->isLocal())
scope = scope->nestedIn;
if (scope && scope->type == Scope::eFunction) {
const Function *func = scope->function;
if (func) {
const Token *ret = func->retDef;
while (Token::Match(ret, "static|const"))
ret = ret->next();
return Token::Match(ret, "bool|_Bool");
}
}
return false;
}
static bool isOperandExpanded(const Token *tok)
{
if (tok->isExpandedMacro() || tok->isEnumerator())
return true;
if (tok->astOperand1() && isOperandExpanded(tok->astOperand1()))
return true;
if (tok->astOperand2() && isOperandExpanded(tok->astOperand2()))
return true;
return false;
}
void CheckCondition::checkBadBitmaskCheck()
{
if (!mSettings->severity.isEnabled(Severity::style) && !mSettings->isPremiumEnabled("badBitmaskCheck"))
return;
logChecker("CheckCondition::checkBadBitmaskCheck"); // style
for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
if (tok->str() == "|" && tok->astOperand1() && tok->astOperand2() && tok->astParent()) {
const Token* parent = tok->astParent();
const bool isBoolean = Token::Match(parent, "&&|%oror%") ||
(parent->str() == "?" && parent->astOperand1() == tok) ||
(parent->str() == "=" && parent->astOperand2() == tok && parent->astOperand1() && parent->astOperand1()->variable() && Token::Match(parent->astOperand1()->variable()->typeStartToken(), "bool|_Bool")) ||
(parent->str() == "(" && Token::Match(parent->astOperand1(), "if|while")) ||
(parent->str() == "return" && parent->astOperand1() == tok && inBooleanFunction(tok));
const bool isTrue = (tok->astOperand1()->hasKnownIntValue() && tok->astOperand1()->values().front().intvalue != 0) ||
(tok->astOperand2()->hasKnownIntValue() && tok->astOperand2()->values().front().intvalue != 0);
if (isBoolean && isTrue)
badBitmaskCheckError(tok);
// If there are #ifdef in the expression don't warn about redundant | to avoid FP
const auto& startStop = tok->findExpressionStartEndTokens();
if (mTokenizer->hasIfdef(startStop.first, startStop.second))
continue;
const bool isZero1 = (tok->astOperand1()->hasKnownIntValue() && tok->astOperand1()->values().front().intvalue == 0);
const bool isZero2 = (tok->astOperand2()->hasKnownIntValue() && tok->astOperand2()->values().front().intvalue == 0);
if (!isZero1 && !isZero2)
continue;
if (!tok->isExpandedMacro() &&
!(isZero1 && isOperandExpanded(tok->astOperand1())) &&
!(isZero2 && isOperandExpanded(tok->astOperand2())))
badBitmaskCheckError(tok, /*isNoOp*/ true);
}
}
}
void CheckCondition::badBitmaskCheckError(const Token *tok, bool isNoOp)
{
if (isNoOp)
reportError(tok, Severity::style, "badBitmaskCheck", "Operator '|' with one operand equal to zero is redundant.", CWE571, Certainty::normal);
else
reportError(tok, Severity::warning, "badBitmaskCheck", "Result of operator '|' is always true if one operand is non-zero. Did you intend to use '&'?", CWE571, Certainty::normal);
}
void CheckCondition::comparison()
{
if (!mSettings->severity.isEnabled(Severity::style) && !mSettings->isPremiumEnabled("comparisonError"))
return;
logChecker("CheckCondition::comparison"); // style
for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
if (!tok->isComparisonOp())
continue;
const Token *expr1 = tok->astOperand1();
const Token *expr2 = tok->astOperand2();
if (!expr1 || !expr2)
continue;
if (expr1->hasKnownIntValue())
std::swap(expr1,expr2);
if (!expr2->hasKnownIntValue())
continue;
if (!compareTokenFlags(expr1, expr2, /*macro*/ true))
continue;
const MathLib::bigint num2 = expr2->getKnownIntValue();
if (num2 < 0)
continue;
if (!Token::Match(expr1,"[&|]"))
continue;
std::list<MathLib::bigint> numbers;
getnumchildren(expr1, numbers);
for (const MathLib::bigint num1 : numbers) {
if (num1 < 0)
continue;
if (Token::Match(tok, "==|!=")) {
if ((expr1->str() == "&" && (num1 & num2) != num2) ||
(expr1->str() == "|" && (num1 | num2) != num2)) {
const std::string& op(tok->str());
comparisonError(expr1, expr1->str(), num1, op, num2, op != "==");
}
} else if (expr1->str() == "&") {
const bool or_equal = Token::Match(tok, ">=|<=");
const std::string& op(tok->str());
if ((Token::Match(tok, ">=|<")) && (num1 < num2)) {
comparisonError(expr1, expr1->str(), num1, op, num2, !or_equal);
} else if ((Token::Match(tok, "<=|>")) && (num1 <= num2)) {
comparisonError(expr1, expr1->str(), num1, op, num2, or_equal);
}
} else if (expr1->str() == "|") {
if ((expr1->astOperand1()->valueType()) &&
(expr1->astOperand1()->valueType()->sign == ValueType::Sign::UNSIGNED)) {
const bool or_equal = Token::Match(tok, ">=|<=");
const std::string& op(tok->str());
if ((Token::Match(tok, ">=|<")) && (num1 >= num2)) {
//"(a | 0x07) >= 7U" is always true for unsigned a
//"(a | 0x07) < 7U" is always false for unsigned a
comparisonError(expr1, expr1->str(), num1, op, num2, or_equal);
} else if ((Token::Match(tok, "<=|>")) && (num1 > num2)) {
//"(a | 0x08) <= 7U" is always false for unsigned a
//"(a | 0x07) > 6U" is always true for unsigned a
comparisonError(expr1, expr1->str(), num1, op, num2, !or_equal);
}
}
}
}
}
}
void CheckCondition::comparisonError(const Token *tok, const std::string &bitop, MathLib::bigint value1, const std::string &op, MathLib::bigint value2, bool result)
{
std::ostringstream expression;
expression << std::hex << "(X " << bitop << " 0x" << value1 << ") " << op << " 0x" << value2;
const std::string errmsg("Expression '" + expression.str() + "' is always " + bool_to_string(result) + ".\n"
"The expression '" + expression.str() + "' is always " + bool_to_string(result) +
". Check carefully constants and operators used, these errors might be hard to "
"spot sometimes. In case of complex expression it might help to split it to "
"separate expressions.");
reportError(tok, Severity::style, "comparisonError", errmsg, CWE398, Certainty::normal);
}
bool CheckCondition::isOverlappingCond(const Token * const cond1, const Token * const cond2, bool pure) const
{
if (!cond1 || !cond2)
return false;
// same expressions
if (isSameExpression(true, cond1, cond2, *mSettings, pure, false))
return true;
// bitwise overlap for example 'x&7' and 'x==1'
if (cond1->str() == "&" && cond1->astOperand1() && cond2->astOperand2()) {
const Token *expr1 = cond1->astOperand1();
const Token *num1 = cond1->astOperand2();
if (!num1) // unary operator&
return false;
if (!num1->isNumber())
std::swap(expr1,num1);
if (!num1->isNumber() || MathLib::isNegative(num1->str()))
return false;
if (!Token::Match(cond2, "&|==") || !cond2->astOperand1() || !cond2->astOperand2())
return false;
const Token *expr2 = cond2->astOperand1();
const Token *num2 = cond2->astOperand2();
if (!num2->isNumber())
std::swap(expr2,num2);
if (!num2->isNumber() || MathLib::isNegative(num2->str()))
return false;
if (!isSameExpression(true, expr1, expr2, *mSettings, pure, false))
return false;
const MathLib::bigint value1 = MathLib::toBigNumber(num1);
const MathLib::bigint value2 = MathLib::toBigNumber(num2);
if (cond2->str() == "&")
return ((value1 & value2) == value2);
return ((value1 & value2) > 0);
}
return false;
}
void CheckCondition::duplicateCondition()
{
if (!mSettings->severity.isEnabled(Severity::style) && !mSettings->isPremiumEnabled("duplicateCondition"))
return;
logChecker("CheckCondition::duplicateCondition"); // style
const SymbolDatabase *const symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope &scope : symbolDatabase->scopeList) {
if (scope.type != Scope::eIf)
continue;
const Token* tok2 = scope.classDef->next();
if (!tok2)
continue;
const Token* cond1 = tok2->astOperand2();
if (!cond1)
continue;
if (cond1->hasKnownIntValue())
continue;
tok2 = tok2->link();
if (!Token::simpleMatch(tok2, ") {"))
continue;
tok2 = tok2->linkAt(1);
if (!Token::simpleMatch(tok2, "} if ("))
continue;
const Token *cond2 = tok2->tokAt(2)->astOperand2();
if (!cond2)
continue;
ErrorPath errorPath;
if (!findExpressionChanged(cond1, scope.classDef->next(), cond2, *mSettings) &&
isSameExpression(true, cond1, cond2, *mSettings, true, true, &errorPath))
duplicateConditionError(cond1, cond2, std::move(errorPath));
}
}
void CheckCondition::duplicateConditionError(const Token *tok1, const Token *tok2, ErrorPath errorPath)
{
if (diag(tok1) & diag(tok2))
return;
errorPath.emplace_back(tok1, "First condition");
errorPath.emplace_back(tok2, "Second condition");
std::string msg = "The if condition is the same as the previous if condition";
reportError(errorPath, Severity::style, "duplicateCondition", msg, CWE398, Certainty::normal);
}
void CheckCondition::multiCondition()
{
if (!mSettings->severity.isEnabled(Severity::style) && !mSettings->isPremiumEnabled("multiCondition"))
return;
logChecker("CheckCondition::multiCondition"); // style
const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope &scope : symbolDatabase->scopeList) {
if (scope.type != Scope::eIf)
continue;
const Token * const cond1 = scope.classDef->next()->astOperand2();
if (!cond1)
continue;
const Token * tok2 = scope.classDef->next();
// Check each 'else if'
for (;;) {
tok2 = tok2->link();
if (!Token::simpleMatch(tok2, ") {"))
break;
tok2 = tok2->linkAt(1);
if (!Token::simpleMatch(tok2, "} else { if ("))
break;
tok2 = tok2->tokAt(4);
if (tok2->astOperand2()) {
ErrorPath errorPath;
if (isOverlappingCond(cond1, tok2->astOperand2(), true) &&
!findExpressionChanged(cond1, cond1, tok2->astOperand2(), *mSettings))
overlappingElseIfConditionError(tok2->astOperand2(), cond1->linenr());
else if (isOppositeCond(
true, cond1, tok2->astOperand2(), *mSettings, true, true, &errorPath) &&
!findExpressionChanged(cond1, cond1, tok2->astOperand2(), *mSettings))
oppositeElseIfConditionError(cond1, tok2->astOperand2(), std::move(errorPath));
}
}
}
}
void CheckCondition::overlappingElseIfConditionError(const Token *tok, nonneg int line1)
{
if (diag(tok))
return;
std::ostringstream errmsg;
errmsg << "Expression is always false because 'else if' condition matches previous condition at line "
<< line1 << ".";
reportError(tok, Severity::style, "multiCondition", errmsg.str(), CWE398, Certainty::normal);
}
void CheckCondition::oppositeElseIfConditionError(const Token *ifCond, const Token *elseIfCond, ErrorPath errorPath)
{
if (diag(ifCond) & diag(elseIfCond))
return;
std::ostringstream errmsg;
errmsg << "Expression is always true because 'else if' condition is opposite to previous condition at line "
<< ifCond->linenr() << ".";
errorPath.emplace_back(ifCond, "first condition");
errorPath.emplace_back(elseIfCond, "else if condition is opposite to first condition");
reportError(errorPath, Severity::style, "multiCondition", errmsg.str(), CWE398, Certainty::normal);
}
//---------------------------------------------------------------------------
// - Opposite inner conditions => always false
// - (TODO) Same/Overlapping inner condition => always true
// - same condition after early exit => always false
//---------------------------------------------------------------------------
static bool isNonConstFunctionCall(const Token *ftok, const Library &library)
{
if (library.isFunctionConst(ftok))
return false;
const Token *obj = ftok->next()->astOperand1();
while (obj && obj->str() == ".")
obj = obj->astOperand1();
if (!obj)
return true;
if (obj->variable() && obj->variable()->isConst())
return false;
if (ftok->function() && ftok->function()->isConst())
return false;
return true;
}
void CheckCondition::multiCondition2()
{
if (!mSettings->severity.isEnabled(Severity::warning) &&
!mSettings->isPremiumEnabled("identicalConditionAfterEarlyExit") &&
!mSettings->isPremiumEnabled("identicalInnerCondition"))
return;
logChecker("CheckCondition::multiCondition2"); // warning
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope &scope : symbolDatabase->scopeList) {
const Token *condTok = nullptr;
if (scope.type == Scope::eIf || scope.type == Scope::eWhile)
condTok = scope.classDef->next()->astOperand2();
else if (scope.type == Scope::eFor) {
condTok = scope.classDef->next()->astOperand2();
if (!condTok || condTok->str() != ";")
continue;
condTok = condTok->astOperand2();
if (!condTok || condTok->str() != ";")
continue;
condTok = condTok->astOperand1();
}
if (!condTok)
continue;
const Token * const cond1 = condTok;
if (!Token::simpleMatch(scope.classDef->linkAt(1), ") {"))
continue;
bool functionCall = false;
bool nonConstFunctionCall = false;
bool nonlocal = false; // nonlocal variable used in condition
std::set<int> vars; // variables used in condition
visitAstNodes(condTok,
[&](const Token *cond) {
if (Token::Match(cond, "%name% (")) {
functionCall = true;
nonConstFunctionCall = isNonConstFunctionCall(cond, mSettings->library);
if (nonConstFunctionCall)
return ChildrenToVisit::done;
}
if (cond->varId()) {
vars.insert(cond->varId());
const Variable *var = cond->variable();
if (!nonlocal && var) {
if (!(var->isLocal() || var->isArgument()))
nonlocal = true;
else if ((var->isPointer() || var->isReference()) && !Token::Match(cond->astParent(), "%oror%|&&|!"))
// TODO: if var is pointer check what it points at
nonlocal = true;
}
} else if (!nonlocal && cond->isName()) {
// varid is 0. this is possibly a nonlocal variable..
nonlocal = Token::Match(cond->astParent(), "%cop%|(|[") || Token::Match(cond, "%name% .") || (cond->isCpp() && cond->str() == "this");
} else {
return ChildrenToVisit::op1_and_op2;
}
return ChildrenToVisit::none;
});
if (nonConstFunctionCall)
continue;
std::vector<const Variable*> varsInCond;
visitAstNodes(condTok,
[&varsInCond](const Token *cond) {
if (cond->variable()) {
const Variable *var = cond->variable();
if (std::find(varsInCond.cbegin(), varsInCond.cend(), var) == varsInCond.cend())
varsInCond.push_back(var);
}
return ChildrenToVisit::op1_and_op2;
});
// parse until second condition is reached..
enum MULTICONDITIONTYPE : std::uint8_t { INNER, AFTER };
const Token *tok;
// Parse inner condition first and then early return condition
std::vector<MULTICONDITIONTYPE> types = {MULTICONDITIONTYPE::INNER};
if (Token::Match(scope.bodyStart, "{ return|throw|continue|break"))
types.push_back(MULTICONDITIONTYPE::AFTER);
for (const MULTICONDITIONTYPE type:types) {
if (type == MULTICONDITIONTYPE::AFTER) {
tok = scope.bodyEnd->next();
} else {
tok = scope.bodyStart;
}
const Token * const endToken = tok->scope()->bodyEnd;
for (; tok && tok != endToken; tok = tok->next()) {
if (isExpressionChangedAt(cond1, tok, 0, false, *mSettings))
break;
if (Token::Match(tok, "if|return")) {
const Token * condStartToken = tok->str() == "if" ? tok->next() : tok;
const Token * condEndToken = tok->str() == "if" ? condStartToken->link() : Token::findsimplematch(condStartToken, ";");
// Does condition modify tracked variables?
if (findExpressionChanged(cond1, condStartToken, condEndToken, *mSettings))
break;
// Condition..
const Token *cond2 = tok->str() == "if" ? condStartToken->astOperand2() : condStartToken->astOperand1();
const bool isReturnVar = (tok->str() == "return" && (!Token::Match(cond2, "%cop%") || (cond2 && cond2->isUnaryOp("!"))));
ErrorPath errorPath;
if (type == MULTICONDITIONTYPE::INNER) {
visitAstNodes(cond1, [&](const Token* firstCondition) {
if (!firstCondition)
return ChildrenToVisit::none;
if (firstCondition->str() == "&&") {
if (!isOppositeCond(false, firstCondition, cond2, *mSettings, true, true))
return ChildrenToVisit::op1_and_op2;
}
if (!firstCondition->hasKnownIntValue()) {
if (!isReturnVar && isOppositeCond(false, firstCondition, cond2, *mSettings, true, true, &errorPath)) {
if (!isAliased(vars))
oppositeInnerConditionError(firstCondition, cond2, errorPath);
} else if (!isReturnVar && isSameExpression(true, firstCondition, cond2, *mSettings, true, true, &errorPath)) {
identicalInnerConditionError(firstCondition, cond2, errorPath);
}
}
return ChildrenToVisit::none;
});
} else {
visitAstNodes(cond2, [&](const Token *secondCondition) {
if (secondCondition->str() == "||" || secondCondition->str() == "&&")
return ChildrenToVisit::op1_and_op2;
if ((!cond1->hasKnownIntValue() || !secondCondition->hasKnownIntValue()) &&
isSameExpression(true, cond1, secondCondition, *mSettings, true, true, &errorPath)) {
if (!isAliased(vars) && !mTokenizer->hasIfdef(cond1, secondCondition)) {
identicalConditionAfterEarlyExitError(cond1, secondCondition, errorPath);
return ChildrenToVisit::done;
}
}
return ChildrenToVisit::none;
});
}
}
if (Token::Match(tok, "%name% (") &&
isVariablesChanged(tok, tok->linkAt(1), 0, varsInCond, *mSettings)) {
break;
}
if (Token::Match(tok, "%type% (") && nonlocal && isNonConstFunctionCall(tok, mSettings->library)) // non const function call -> bailout if there are nonlocal variables
break;
if (Token::Match(tok, "case|break|continue|return|throw") && tok->scope() == endToken->scope())
break;
if (Token::Match(tok, "[;{}] %name% :"))
break;
// bailout if loop is seen.
// TODO: handle loops better.
if (Token::Match(tok, "for|while|do")) {
const Token *tok1 = tok->next();
const Token *tok2;
if (Token::simpleMatch(tok, "do {")) {
if (!Token::simpleMatch(tok->linkAt(1), "} while ("))
break;
tok2 = tok->linkAt(1)->linkAt(2);
} else if (Token::Match(tok, "if|while (")) {
tok2 = tok->linkAt(1);
if (Token::simpleMatch(tok2, ") {"))
tok2 = tok2->linkAt(1);
if (!tok2)
break;
} else {
// Incomplete code
break;
}
const bool changed = std::any_of(vars.cbegin(), vars.cend(), [&](int varid) {
return isVariableChanged(tok1, tok2, varid, nonlocal, *mSettings);
});
if (changed)
break;
}
if ((tok->varId() && vars.find(tok->varId()) != vars.end()) ||
(!tok->varId() && nonlocal) ||
(functionCall && tok->variable() && !tok->variable()->isLocal())) {
if (Token::Match(tok, "%name% %assign%|++|--"))
break;
if (Token::Match(tok->astParent(), "*|.|[")) {
const Token *parent = tok;
while (Token::Match(parent->astParent(), ".|[") || (parent->astParent() && parent->astParent()->isUnaryOp("*")))
parent = parent->astParent();
if (Token::Match(parent->astParent(), "%assign%|++|--"))
break;
}
if (tok->isCpp() && Token::Match(tok, "%name% <<") && (!tok->valueType() || !tok->valueType()->isIntegral()))
break;
if (isLikelyStreamRead(tok->next()) || isLikelyStreamRead(tok->previous()))
break;
if (Token::Match(tok, "%name% [")) {
const Token *tok2 = tok->linkAt(1);
while (Token::simpleMatch(tok2, "] ["))
tok2 = tok2->linkAt(1);
if (Token::Match(tok2, "] %assign%|++|--"))
break;
}
if (Token::Match(tok->previous(), "++|--|& %name%"))
break;
if (tok->variable() &&
!tok->variable()->isConst() &&
Token::Match(tok, "%name% . %name% (")) {
const Function* function = tok->tokAt(2)->function();
if (!function || !function->isConst())
break;
}
if (Token::Match(tok->previous(), "[(,] *|& %name% [,)]") && isParameterChanged(tok))
break;
}
}
}
}
}
static std::string innerSmtString(const Token * tok)
{
if (!tok)
return "if";
const Token * top = tok->astTop();
if (top->str() == "(" && top->astOperand1())
return top->astOperand1()->str();
return top->str();
}
void CheckCondition::oppositeInnerConditionError(const Token *tok1, const Token* tok2, ErrorPath errorPath)
{
if (diag(tok1) & diag(tok2))
return;
const std::string s1(tok1 ? tok1->expressionString() : "x");
const std::string s2(tok2 ? tok2->expressionString() : "!x");
const std::string innerSmt = innerSmtString(tok2);
errorPath.emplace_back(tok1, "outer condition: " + s1);
errorPath.emplace_back(tok2, "opposite inner condition: " + s2);
const std::string msg("Opposite inner '" + innerSmt + "' condition leads to a dead code block.\n"
"Opposite inner '" + innerSmt + "' condition leads to a dead code block (outer condition is '" + s1 + "' and inner condition is '" + s2 + "').");
reportError(errorPath, Severity::warning, "oppositeInnerCondition", msg, CWE398, Certainty::normal);
}
void CheckCondition::identicalInnerConditionError(const Token *tok1, const Token* tok2, ErrorPath errorPath)
{
if (diag(tok1) & diag(tok2))
return;
const std::string s1(tok1 ? tok1->expressionString() : "x");
const std::string s2(tok2 ? tok2->expressionString() : "x");
const std::string innerSmt = innerSmtString(tok2);
errorPath.emplace_back(tok1, "outer condition: " + s1);
errorPath.emplace_back(tok2, "identical inner condition: " + s2);
const std::string msg("Identical inner '" + innerSmt + "' condition is always true.\n"
"Identical inner '" + innerSmt + "' condition is always true (outer condition is '" + s1 + "' and inner condition is '" + s2 + "').");
reportError(errorPath, Severity::warning, "identicalInnerCondition", msg, CWE398, Certainty::normal);
}
void CheckCondition::identicalConditionAfterEarlyExitError(const Token *cond1, const Token* cond2, ErrorPath errorPath)
{
if (diag(cond1) & diag(cond2))
return;
const bool isReturnValue = cond2 && Token::simpleMatch(cond2->astParent(), "return");
const std::string cond(cond1 ? cond1->expressionString() : "x");
const std::string value = (cond2 && cond2->valueType() && cond2->valueType()->type == ValueType::Type::BOOL) ? "false" : "0";
errorPath.emplace_back(cond1, "If condition '" + cond + "' is true, the function will return/exit");
errorPath.emplace_back(cond2, (isReturnValue ? "Returning identical expression '" : "Testing identical condition '") + cond + "'");
reportError(errorPath,
Severity::warning,
"identicalConditionAfterEarlyExit",
isReturnValue
? ("Identical condition and return expression '" + cond + "', return value is always " + value)
: ("Identical condition '" + cond + "', second condition is always false"),
CWE398,
Certainty::normal);
}
//---------------------------------------------------------------------------
// if ((x != 1) || (x != 3)) // expression always true
// if ((x == 1) && (x == 3)) // expression always false
// if ((x < 1) && (x > 3)) // expression always false
// if ((x > 3) || (x < 10)) // expression always true
// if ((x > 5) && (x != 1)) // second comparison always true
//
// Check for suspect logic for an expression consisting of 2 comparison
// expressions with a shared variable and constants and a logical operator
// between them.
//
// Suggest a different logical operator when the logical operator between
// the comparisons is probably wrong.
//
// Inform that second comparison is always true when first comparison is true.
//---------------------------------------------------------------------------
static std::string invertOperatorForOperandSwap(std::string s)
{
if (s[0] == '<')
s[0] = '>';
else if (s[0] == '>')
s[0] = '<';
return s;
}
template<typename T>
static int sign(const T v) {
return static_cast<int>(v > 0) - static_cast<int>(v < 0);
}
// returns 1 (-1) if the first (second) condition is sufficient, 0 if indeterminate
template<typename T>
static int sufficientCondition(std::string op1, const bool not1, const T value1, std::string op2, const bool not2, const T value2, const bool isAnd) {
auto transformOp = [](std::string& op, const bool invert) {
if (invert) {
if (op == "==")
op = "!=";
else if (op == "!=")
op = "==";
else if (op == "<")
op = ">=";
else if (op == ">")
op = "<=";
else if (op == "<=")
op = ">";
else if (op == ">=")
op = "<";
}
};
transformOp(op1, not1);
transformOp(op2, not2);
int res = 0;
bool equal = false;
if (op1 == op2) {
equal = true;
if (op1 == ">" || op1 == ">=")
res = sign(value1 - value2);
else if (op1 == "<" || op1 == "<=")
res = -sign(value1 - value2);
} else { // not equal
if (op1 == "!=")
res = 1;
else if (op2 == "!=")
res = -1;
else if (op1 == "==")
res = -1;
else if (op2 == "==")
res = 1;
else if (op1 == ">" && op2 == ">=")
res = sign(value1 - (value2 - 1));
else if (op1 == ">=" && op2 == ">")
res = sign((value1 - 1) - value2);
else if (op1 == "<" && op2 == "<=")
res = -sign(value1 - (value2 + 1));
else if (op1 == "<=" && op2 == "<")
res = -sign((value1 + 1) - value2);
}
return res * (isAnd == equal ? 1 : -1);
}
template<typename T>
static bool checkIntRelation(const std::string &op, const T value1, const T value2)
{
return (op == "==" && value1 == value2) ||
(op == "!=" && value1 != value2) ||
(op == ">" && value1 > value2) ||
(op == ">=" && value1 >= value2) ||
(op == "<" && value1 < value2) ||
(op == "<=" && value1 <= value2);
}
static bool checkFloatRelation(const std::string &op, const double value1, const double value2)
{
return (op == ">" && value1 > value2) ||
(op == ">=" && value1 >= value2) ||
(op == "<" && value1 < value2) ||
(op == "<=" && value1 <= value2);
}
template<class T>
static T getvalue3(const T value1, const T value2)
{