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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2025 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/>.
*/
//---------------------------------------------------------------------------
// You should not write statements with side effects in assert()
//---------------------------------------------------------------------------
#include "checkassert.h"
#include "astutils.h"
#include "errortypes.h"
#include "library.h"
#include "settings.h"
#include "symboldatabase.h"
#include "token.h"
#include "tokenize.h"
#include "tokenlist.h"
#include <algorithm>
#include <utility>
//---------------------------------------------------------------------------
// CWE ids used
static const CWE CWE398(398U); // Indicator of Poor Code Quality
// Register this check class (by creating a static instance of it)
namespace {
CheckAssert instance;
}
void CheckAssert::assertWithSideEffects()
{
if (!mSettings->severity.isEnabled(Severity::warning))
return;
logChecker("CheckAssert::assertWithSideEffects"); // warning
for (const Token* tok = mTokenizer->list.front(); tok; tok = tok->next()) {
if (!Token::simpleMatch(tok, "assert ("))
continue;
const Token *endTok = tok->linkAt(1);
for (const Token* tmp = tok->next(); tmp != endTok; tmp = tmp->next()) {
if (Token::simpleMatch(tmp, "sizeof ("))
tmp = tmp->linkAt(1);
checkVariableAssignment(tmp, tok->scope());
if (tmp->tokType() != Token::eFunction) {
if (const Library::Function* f = mSettings->library.getFunction(tmp)) {
if (f->isconst || f->ispure)
continue;
if (Library::getContainerYield(tmp->next()) != Library::Container::Yield::NO_YIELD) // bailout, assume read access
continue;
if (std::any_of(f->argumentChecks.begin(), f->argumentChecks.end(), [](const std::pair<int, Library::ArgumentChecks>& ac) {
return ac.second.iteratorInfo.container > 0; // bailout, takes iterators -> assume read access
}))
continue;
if (tmp->str() == "get" && Token::simpleMatch(tmp->astParent(), ".") && astIsSmartPointer(tmp->astParent()->astOperand1()))
continue;
if (f->containerYield == Library::Container::Yield::START_ITERATOR || // bailout for std::begin/end/prev/next
f->containerYield == Library::Container::Yield::END_ITERATOR ||
f->containerYield == Library::Container::Yield::ITERATOR)
continue;
sideEffectInAssertError(tmp, mSettings->library.getFunctionName(tmp));
}
continue;
}
const Function* f = tmp->function();
const Scope* scope = f->functionScope;
if (!scope) {
// guess that const method doesn't have side effects
if (f->nestedIn->isClassOrStruct() && !f->isConst() && !f->isStatic())
sideEffectInAssertError(tmp, f->name()); // Non-const member function called, assume it has side effects
continue;
}
for (const Token *tok2 = scope->bodyStart; tok2 != scope->bodyEnd; tok2 = tok2->next()) {
if (!tok2->isAssignmentOp() && tok2->tokType() != Token::eIncDecOp)
continue;
const Variable* var = tok2->previous()->variable();
if (!var || var->isLocal() || (var->isArgument() && !var->isReference() && !var->isPointer()))
continue; // See ticket #4937. Assigning function arguments not passed by reference is ok.
if (var->isArgument() && var->isPointer() && tok2->strAt(-2) != "*")
continue; // Pointers need to be dereferenced, otherwise there is no error
bool noReturnInScope = true;
for (const Token *rt = scope->bodyStart; rt != scope->bodyEnd; rt = rt->next()) {
if (rt->str() != "return") continue; // find all return statements
if (inSameScope(rt, tok2)) {
noReturnInScope = false;
break;
}
}
if (noReturnInScope) continue;
sideEffectInAssertError(tmp, f->name());
break;
}
}
tok = endTok;
}
}
//---------------------------------------------------------------------------
void CheckAssert::sideEffectInAssertError(const Token *tok, const std::string& functionName)
{
reportError(tok, Severity::warning,
"assertWithSideEffect",
"$symbol:" + functionName + "\n"
"Assert statement calls a function which may have desired side effects: '$symbol'.\n"
"Non-pure function: '$symbol' is called inside assert statement. "
"Assert statements are removed from release builds so the code inside "
"assert statement is not executed. If the code is needed also in release "
"builds, this is a bug.", CWE398, Certainty::normal);
}
void CheckAssert::assignmentInAssertError(const Token *tok, const std::string& varname)
{
reportError(tok, Severity::warning,
"assignmentInAssert",
"$symbol:" + varname + "\n"
"Assert statement modifies '$symbol'.\n"
"Variable '$symbol' is modified inside assert statement. "
"Assert statements are removed from release builds so the code inside "
"assert statement is not executed. If the code is needed also in release "
"builds, this is a bug.", CWE398, Certainty::normal);
}
// checks if side effects happen on the variable prior to tmp
void CheckAssert::checkVariableAssignment(const Token* assignTok, const Scope *assertionScope)
{
if (!assignTok->isAssignmentOp() && assignTok->tokType() != Token::eIncDecOp)
return;
if (!assignTok->astOperand1())
return;
const Variable* var = assignTok->astOperand1()->variable();
if (!var)
return;
// Variable declared in inner scope in assert => don't warn
if (assertionScope != var->scope()) {
const Scope *s = var->scope();
while (s && s != assertionScope)
s = s->nestedIn;
if (s == assertionScope)
return;
}
// assignment
if (assignTok->isAssignmentOp() || assignTok->tokType() == Token::eIncDecOp) {
if (var->isConst()) {
return;
}
assignmentInAssertError(assignTok, var->name());
}
// TODO: function calls on var
}
bool CheckAssert::inSameScope(const Token* returnTok, const Token* assignTok)
{
// TODO: even if a return is in the same scope, the assignment might not affect it.
return returnTok->scope() == assignTok->scope();
}
void CheckAssert::runChecks(const Tokenizer &tokenizer, ErrorLogger *errorLogger)
{
CheckAssert checkAssert(&tokenizer, &tokenizer.getSettings(), errorLogger);
checkAssert.assertWithSideEffects();
}
void CheckAssert::getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const
{
CheckAssert c(nullptr, settings, errorLogger);
c.sideEffectInAssertError(nullptr, "function");
c.assignmentInAssertError(nullptr, "var");
}
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