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cppcheck/lib/checkautovariables.cpp

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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2021 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/>.
*/
//---------------------------------------------------------------------------
// Auto variables checks
//---------------------------------------------------------------------------
#include "checkautovariables.h"
#include "astutils.h"
#include "library.h"
#include "settings.h"
#include "symboldatabase.h"
#include "token.h"
#include "tokenize.h"
#include "valueflow.h"
#include <algorithm>
#include <list>
//---------------------------------------------------------------------------
// Register this check class into cppcheck by creating a static instance of it..
namespace {
CheckAutoVariables instance;
}
static const CWE CWE398(398U); // Indicator of Poor Code Quality
static const CWE CWE562(562U); // Return of Stack Variable Address
static const CWE CWE590(590U); // Free of Memory not on the Heap
static bool isPtrArg(const Token *tok)
{
const Variable *var = tok->variable();
return (var && var->isArgument() && var->isPointer());
}
static bool isArrayArg(const Token *tok)
{
const Variable *var = tok->variable();
return (var && var->isArgument() && var->isArray());
}
static bool isArrayVar(const Token *tok)
{
const Variable *var = tok->variable();
return (var && var->isArray());
}
static bool isRefPtrArg(const Token *tok)
{
const Variable *var = tok->variable();
return (var && var->isArgument() && var->isReference() && var->isPointer());
}
static bool isNonReferenceArg(const Token *tok)
{
const Variable *var = tok->variable();
return (var && var->isArgument() && !var->isReference() && (var->isPointer() || (var->valueType() && var->valueType()->type >= ValueType::Type::CONTAINER) || var->type()));
}
static bool isAutoVar(const Token *tok)
{
const Variable *var = tok->variable();
if (!var || !var->isLocal() || var->isStatic())
return false;
if (var->isReference()) {
// address of reference variable can be taken if the address
// of the variable it points at is not a auto-var
// TODO: check what the reference variable references.
return false;
}
if (Token::Match(tok, "%name% .|::")) {
do {
tok = tok->tokAt(2);
} while (Token::Match(tok, "%name% .|::"));
if (Token::Match(tok, "%name% ("))
return false;
}
return true;
}
static bool isAutoVarArray(const Token *tok)
{
if (!tok)
return false;
// &x[..]
if (tok->isUnaryOp("&") && Token::simpleMatch(tok->astOperand1(), "["))
return isAutoVarArray(tok->astOperand1()->astOperand1());
// x+y
if (tok->str() == "+")
return isAutoVarArray(tok->astOperand1()) || isAutoVarArray(tok->astOperand2());
// x-intexpr
if (tok->str() == "-")
return isAutoVarArray(tok->astOperand1()) &&
tok->astOperand2() &&
tok->astOperand2()->valueType() &&
tok->astOperand2()->valueType()->isIntegral();
const Variable *var = tok->variable();
if (!var)
return false;
// Variable
if (var->isLocal() && !var->isStatic() && var->isArray() && !var->isPointer())
return true;
// ValueFlow
if (var->isPointer() && !var->isArgument()) {
for (std::list<ValueFlow::Value>::const_iterator it = tok->values().begin(); it != tok->values().end(); ++it) {
const ValueFlow::Value &val = *it;
if (val.isTokValue() && isAutoVarArray(val.tokvalue))
return true;
}
}
return false;
}
// Verification that we really take the address of a local variable
static bool checkRvalueExpression(const Token * const vartok)
{
const Variable * const var = vartok->variable();
if (var == nullptr)
return false;
if (Token::Match(vartok->previous(), "& %name% [") && var->isPointer())
return false;
const Token * const next = vartok->next();
// &a.b[0]
if (Token::Match(vartok, "%name% . %var% [") && !var->isPointer()) {
const Variable *var2 = next->next()->variable();
return var2 && !var2->isPointer();
}
return ((next->str() != "." || (!var->isPointer() && (!var->isClass() || var->type()))) && next->strAt(2) != ".");
}
static bool isAddressOfLocalVariable(const Token *expr)
{
if (!expr)
return false;
if (Token::Match(expr, "+|-"))
return isAddressOfLocalVariable(expr->astOperand1()) || isAddressOfLocalVariable(expr->astOperand2());
if (expr->isCast())
return isAddressOfLocalVariable(expr->astOperand2() ? expr->astOperand2() : expr->astOperand1());
if (expr->isUnaryOp("&")) {
const Token *op = expr->astOperand1();
bool deref = false;
while (Token::Match(op, ".|[")) {
if (op->originalName() == "->")
return false;
if (op->str() == "[")
deref = true;
op = op->astOperand1();
}
return op && isAutoVar(op) && (!deref || !op->variable()->isPointer());
}
return false;
}
static bool variableIsUsedInScope(const Token* start, nonneg int varId, const Scope *scope)
{
if (!start) // Ticket #5024
return false;
for (const Token *tok = start; tok && tok != scope->bodyEnd; tok = tok->next()) {
if (tok->varId() == varId)
return true;
const Scope::ScopeType scopeType = tok->scope()->type;
if (scopeType == Scope::eFor || scopeType == Scope::eDo || scopeType == Scope::eWhile) // In case of loops, better checking would be necessary
return true;
if (Token::simpleMatch(tok, "asm ("))
return true;
}
return false;
}
void CheckAutoVariables::assignFunctionArg()
{
const bool printStyle = mSettings->severity.isEnabled(Severity::style);
const bool printWarning = mSettings->severity.isEnabled(Severity::warning);
if (!printStyle && !printWarning)
return;
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token *tok = scope->bodyStart; tok && tok != scope->bodyEnd; tok = tok->next()) {
// TODO: What happens if this is removed?
if (tok->astParent())
continue;
if (!(tok->isAssignmentOp() || Token::Match(tok, "++|--")) || !Token::Match(tok->astOperand1(), "%var%"))
continue;
const Token* const vartok = tok->astOperand1();
if (isNonReferenceArg(vartok) &&
!Token::Match(vartok->next(), "= %varid% ;", vartok->varId()) &&
!variableIsUsedInScope(Token::findsimplematch(vartok->next(), ";"), vartok->varId(), scope) &&
!Token::findsimplematch(vartok, "goto", scope->bodyEnd)) {
if (vartok->variable()->isPointer() && printWarning)
errorUselessAssignmentPtrArg(vartok);
else if (printStyle)
errorUselessAssignmentArg(vartok);
}
}
}
}
void CheckAutoVariables::autoVariables()
{
const bool printInconclusive = mSettings->certainty.isEnabled(Certainty::inconclusive);
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token *tok = scope->bodyStart; tok && tok != scope->bodyEnd; tok = tok->next()) {
// Skip lambda..
if (const Token *lambdaEndToken = findLambdaEndToken(tok)) {
tok = lambdaEndToken;
continue;
}
// Critical assignment
if (Token::Match(tok, "[;{}] %var% = & %var%") && isRefPtrArg(tok->next()) && isAutoVar(tok->tokAt(4))) {
if (checkRvalueExpression(tok->tokAt(4)))
checkAutoVariableAssignment(tok->next(), false);
} else if (Token::Match(tok, "[;{}] * %var% =") && isPtrArg(tok->tokAt(2)) && isAddressOfLocalVariable(tok->tokAt(3)->astOperand2())) {
checkAutoVariableAssignment(tok->next(), false);
} else if (Token::Match(tok, "[;{}] %var% . %var% =") && isPtrArg(tok->next()) && isAddressOfLocalVariable(tok->tokAt(4)->astOperand2())) {
checkAutoVariableAssignment(tok->next(), false);
} else if (Token::Match(tok, "[;{}] %var% . %var% = %var% ;")) {
// TODO: check if the parameter is only changed temporarily (#2969)
if (printInconclusive && isPtrArg(tok->next())) {
if (isAutoVarArray(tok->tokAt(5)))
checkAutoVariableAssignment(tok->next(), true);
}
tok = tok->tokAt(5);
} else if (Token::Match(tok, "[;{}] * %var% = %var% ;")) {
const Variable * var1 = tok->tokAt(2)->variable();
if (var1 && var1->isArgument() && Token::Match(var1->nameToken()->tokAt(-3), "%type% * *")) {
if (isAutoVarArray(tok->tokAt(4)))
checkAutoVariableAssignment(tok->next(), false);
}
tok = tok->tokAt(4);
} else if (Token::Match(tok, "[;{}] %var% [") && Token::simpleMatch(tok->linkAt(2), "] =") &&
(isPtrArg(tok->next()) || isArrayArg(tok->next())) && isAddressOfLocalVariable(tok->linkAt(2)->next()->astOperand2())) {
errorAutoVariableAssignment(tok->next(), false);
}
// Invalid pointer deallocation
else if ((Token::Match(tok, "%name% ( %var%|%str% ) ;") && mSettings->library.getDeallocFuncInfo(tok)) ||
(mTokenizer->isCPP() && Token::Match(tok, "delete [| ]| (| %var%|%str% !!["))) {
tok = Token::findmatch(tok->next(), "%var%|%str%");
if (isArrayVar(tok) || tok->tokType() == Token::eString)
errorInvalidDeallocation(tok, nullptr);
else if (tok->variable() && tok->variable()->isPointer()) {
for (const ValueFlow::Value &v : tok->values()) {
if (!(v.isTokValue()))
continue;
if (isArrayVar(v.tokvalue) || ((v.tokvalue->tokType() == Token::eString) && !v.isImpossible())) {
errorInvalidDeallocation(tok, &v);
break;
}
}
}
} else if ((Token::Match(tok, "%name% ( & %var% ) ;") && mSettings->library.getDeallocFuncInfo(tok)) ||
(mTokenizer->isCPP() && Token::Match(tok, "delete [| ]| (| & %var% !!["))) {
tok = Token::findmatch(tok->next(), "%var%");
if (isAutoVar(tok))
errorInvalidDeallocation(tok, nullptr);
}
}
}
}
bool CheckAutoVariables::checkAutoVariableAssignment(const Token *expr, bool inconclusive, const Token *startToken)
{
if (!startToken)
startToken = Token::findsimplematch(expr, "=")->next();
for (const Token *tok = startToken; tok; tok = tok->next()) {
if (tok->str() == "}" && tok->scope()->type == Scope::ScopeType::eFunction)
errorAutoVariableAssignment(expr, inconclusive);
if (Token::Match(tok, "return|throw|break|continue")) {
errorAutoVariableAssignment(expr, inconclusive);
return true;
}
if (Token::simpleMatch(tok, "=")) {
const Token *lhs = tok;
while (Token::Match(lhs->previous(), "%name%|.|*"))
lhs = lhs->previous();
const Token *e = expr;
while (e->str() != "=" && lhs->str() == e->str()) {
e = e->next();
lhs = lhs->next();
}
if (lhs->str() == "=")
return false;
}
if (Token::simpleMatch(tok, "if (")) {
const Token *ifStart = tok->linkAt(1)->next();
return checkAutoVariableAssignment(expr, inconclusive, ifStart) || checkAutoVariableAssignment(expr, inconclusive, ifStart->link()->next());
}
if (Token::simpleMatch(tok, "} else {"))
tok = tok->linkAt(2);
}
return false;
}
//---------------------------------------------------------------------------
void CheckAutoVariables::errorReturnAddressToAutoVariable(const Token *tok)
{
reportError(tok, Severity::error, "returnAddressOfAutoVariable", "Address of an auto-variable returned.", CWE562, Certainty::normal);
}
void CheckAutoVariables::errorReturnAddressToAutoVariable(const Token *tok, const ValueFlow::Value *value)
{
reportError(tok, Severity::error, "returnAddressOfAutoVariable", "Address of auto-variable '" + value->tokvalue->astOperand1()->expressionString() + "' returned", CWE562, Certainty::normal);
}
void CheckAutoVariables::errorReturnPointerToLocalArray(const Token *tok)
{
reportError(tok, Severity::error, "returnLocalVariable", "Pointer to local array variable returned.", CWE562, Certainty::normal);
}
void CheckAutoVariables::errorAutoVariableAssignment(const Token *tok, bool inconclusive)
{
if (!inconclusive) {
reportError(tok, Severity::error, "autoVariables",
"Address of local auto-variable assigned to a function parameter.\n"
"Dangerous assignment - the function parameter is assigned the address of a local "
"auto-variable. Local auto-variables are reserved from the stack which "
"is freed when the function ends. So the pointer to a local variable "
"is invalid after the function ends.", CWE562, Certainty::normal);
} else {
reportError(tok, Severity::error, "autoVariables",
"Address of local auto-variable assigned to a function parameter.\n"
"Function parameter is assigned the address of a local auto-variable. "
"Local auto-variables are reserved from the stack which is freed when "
"the function ends. The address is invalid after the function ends and it "
"might 'leak' from the function through the parameter.",
CWE562,
Certainty::inconclusive);
}
}
void CheckAutoVariables::errorReturnAddressOfFunctionParameter(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::error, "returnAddressOfFunctionParameter",
"$symbol:" + varname + "\n"
"Address of function parameter '$symbol' returned.\n"
"Address of the function parameter '$symbol' becomes invalid after the function exits because "
"function parameters are stored on the stack which is freed when the function exits. Thus the returned "
"value is invalid.", CWE562, Certainty::normal);
}
void CheckAutoVariables::errorUselessAssignmentArg(const Token *tok)
{
reportError(tok,
Severity::style,
"uselessAssignmentArg",
"Assignment of function parameter has no effect outside the function.", CWE398, Certainty::normal);
}
void CheckAutoVariables::errorUselessAssignmentPtrArg(const Token *tok)
{
reportError(tok,
Severity::warning,
"uselessAssignmentPtrArg",
"Assignment of function parameter has no effect outside the function. Did you forget dereferencing it?", CWE398, Certainty::normal);
}
//---------------------------------------------------------------------------
static bool isInScope(const Token * tok, const Scope * scope)
{
if (!tok)
return false;
if (!scope)
return false;
const Variable * var = tok->variable();
if (var && (var->isGlobal() || var->isStatic() || var->isExtern()))
return false;
if (tok->scope() && tok->scope()->isNestedIn(scope))
return true;
if (!var)
return false;
if (var->isArgument() && !var->isReference()) {
const Scope * tokScope = tok->scope();
if (!tokScope)
return false;
for (const Scope * argScope:tokScope->nestedList) {
if (argScope && argScope->isNestedIn(scope))
return true;
}
}
return false;
}
static bool isDeadScope(const Token * tok, const Scope * scope)
{
if (!tok)
return false;
if (!scope)
return false;
const Variable * var = tok->variable();
if (var && (!var->isLocal() || var->isStatic() || var->isExtern()))
return false;
if (tok->scope() && tok->scope()->bodyEnd != scope->bodyEnd && precedes(tok->scope()->bodyEnd, scope->bodyEnd))
return true;
return false;
}
static int getPointerDepth(const Token *tok)
{
if (!tok)
return 0;
if (tok->valueType())
return tok->valueType()->pointer;
int n = 0;
std::pair<const Token*, const Token*> decl = Token::typeDecl(tok);
for (const Token* tok2 = decl.first; tok2 != decl.second; tok2 = tok2->next())
if (Token::simpleMatch(tok, "*"))
n++;
return n;
}
static bool isDeadTemporary(bool cpp, const Token* tok, const Token* expr, const Library* library)
{
if (!isTemporary(cpp, tok, library))
return false;
if (expr) {
if (!precedes(nextAfterAstRightmostLeaf(tok->astTop()), nextAfterAstRightmostLeaf(expr->astTop())))
return false;
const Token* parent = tok->astParent();
// Is in a for loop
if (astIsRHS(tok) && Token::simpleMatch(parent, ":") && Token::simpleMatch(parent->astParent(), "(") && Token::simpleMatch(parent->astParent()->previous(), "for (")) {
const Token* braces = parent->astParent()->link()->next();
if (precedes(braces, expr) && precedes(expr, braces->link()))
return false;
}
}
return true;
}
static bool isEscapedReference(const Variable* var)
{
if (!var)
return false;
if (!var->isReference())
return false;
if (!var->declEndToken())
return false;
if (!Token::simpleMatch(var->declEndToken(), "="))
return false;
const Token* vartok = var->declEndToken()->astOperand2();
return !isTemporary(true, vartok, nullptr, false);
}
static bool isDanglingSubFunction(const Token* tokvalue, const Token* tok)
{
if (!tokvalue)
return false;
const Variable* var = tokvalue->variable();
if (!var->isLocal())
return false;
Function* f = Scope::nestedInFunction(tok->scope());
if (!f)
return false;
const Token* parent = tokvalue->astParent();
while (parent && !Token::Match(parent->previous(), "%name% (")) {
parent = parent->astParent();
}
if (!Token::simpleMatch(parent, "("))
return false;
return exprDependsOnThis(parent);
}
static const Variable* getParentVar(const Token* tok)
{
if (!tok)
return nullptr;
if (Token::simpleMatch(tok, "."))
return getParentVar(tok->astOperand1());
return tok->variable();
}
static bool isAssignedToNonLocal(const Token* tok)
{
if (!Token::simpleMatch(tok->astParent(), "="))
return false;
if (!astIsRHS(tok))
return false;
const Variable* var = getParentVar(tok->astParent()->astOperand1());
if (!var)
return false;
return !var->isLocal() || var->isStatic();
}
static std::vector<const Token*> getParentMembers(const Token* tok)
{
if (!tok)
return {};
if (!Token::simpleMatch(tok->astParent(), "."))
return {tok};
const Token* parent = tok;
while (Token::simpleMatch(parent->astParent(), "."))
parent = parent->astParent();
std::vector<const Token*> result;
for (const Token* tok2 : astFlatten(parent, ".")) {
if (Token::simpleMatch(tok2, "(") && Token::simpleMatch(tok2->astOperand1(), ".")) {
std::vector<const Token*> sub = getParentMembers(tok2->astOperand1());
result.insert(result.end(), sub.begin(), sub.end());
}
result.push_back(tok2);
}
return result;
}
static const Token* getParentLifetime(bool cpp, const Token* tok, const Library* library)
{
std::vector<const Token*> members = getParentMembers(tok);
if (members.size() < 2)
return tok;
// Find the first local variable or temporary
auto it = std::find_if(members.rbegin(), members.rend(), [&](const Token* tok2) {
const Variable* var = tok2->variable();
if (var) {
return var->isLocal() || var->isArgument();
} else {
return isTemporary(cpp, tok2, library);
}
});
if (it == members.rend())
return tok;
// If any of the submembers are borrowed types then stop
if (std::any_of(it.base() - 1, members.end() - 1, [&](const Token* tok2) {
if (astIsPointer(tok2) || astIsContainerView(tok2) || astIsIterator(tok2))
return true;
if (!astIsUniqueSmartPointer(tok2)) {
if (astIsSmartPointer(tok2))
return true;
const Token* dotTok = tok2->next();
if (!Token::simpleMatch(dotTok, ".")) {
const Token* endTok = nextAfterAstRightmostLeaf(tok2);
if (Token::simpleMatch(endTok, "."))
dotTok = endTok;
else if (Token::simpleMatch(endTok->next(), "."))
dotTok = endTok->next();
}
// If we are dereferencing the member variable then treat it as borrowed
if (Token::simpleMatch(dotTok, ".") && dotTok->originalName() == "->")
return true;
}
const Variable* var = tok2->variable();
return var && var->isReference();
}))
return nullptr;
return *it;
}
void CheckAutoVariables::checkVarLifetimeScope(const Token * start, const Token * end)
{
const bool printInconclusive = mSettings->certainty.isEnabled(Certainty::inconclusive);
if (!start)
return;
const Scope * scope = start->scope();
if (!scope)
return;
// If the scope is not set correctly then skip checking it
if (scope->bodyStart != start)
return;
bool returnRef = Function::returnsReference(scope->function);
for (const Token *tok = start; tok && tok != end; tok = tok->next()) {
// Return reference from function
if (returnRef && Token::simpleMatch(tok->astParent(), "return")) {
for (const LifetimeToken& lt : getLifetimeTokens(tok, true)) {
if (!printInconclusive && lt.inconclusive)
continue;
const Variable* var = lt.token->variable();
if (var && !var->isGlobal() && !var->isStatic() && !var->isReference() && !var->isRValueReference() &&
isInScope(var->nameToken(), tok->scope())) {
errorReturnReference(tok, lt.errorPath, lt.inconclusive);
break;
} else if (isDeadTemporary(mTokenizer->isCPP(), lt.token, nullptr, &mSettings->library)) {
errorReturnTempReference(tok, lt.errorPath, lt.inconclusive);
break;
}
}
// Assign reference to non-local variable
} else if (Token::Match(tok->previous(), "&|&& %var% =") && tok->astParent() == tok->next() &&
tok->variable() && tok->variable()->nameToken() == tok &&
tok->variable()->declarationId() == tok->varId() && tok->variable()->isStatic() &&
!tok->variable()->isArgument()) {
ErrorPath errorPath;
const Variable *var = getLifetimeVariable(tok, errorPath);
if (var && isInScope(var->nameToken(), tok->scope())) {
errorDanglingReference(tok, var, errorPath);
continue;
}
// Reference to temporary
} else if (tok->variable() && (tok->variable()->isReference() || tok->variable()->isRValueReference())) {
for (const LifetimeToken& lt : getLifetimeTokens(getParentLifetime(tok))) {
if (!printInconclusive && lt.inconclusive)
continue;
const Token * tokvalue = lt.token;
if (isDeadTemporary(mTokenizer->isCPP(), tokvalue, tok, &mSettings->library)) {
errorDanglingTempReference(tok, lt.errorPath, lt.inconclusive);
break;
}
}
}
const bool escape = Token::Match(tok->astParent(), "return|throw");
std::unordered_set<const Token*> exprs;
for (const ValueFlow::Value& val:tok->values()) {
if (!val.isLocalLifetimeValue() && !val.isSubFunctionLifetimeValue())
continue;
if (!printInconclusive && val.isInconclusive())
continue;
const Token* parent = getParentLifetime(mTokenizer->isCPP(), val.tokvalue, &mSettings->library);
if (!exprs.insert(parent).second)
continue;
for (const LifetimeToken& lt : getLifetimeTokens(parent, escape || isAssignedToNonLocal(tok))) {
const Token * tokvalue = lt.token;
if (val.isLocalLifetimeValue()) {
if (escape) {
if (getPointerDepth(tok) < getPointerDepth(tokvalue))
continue;
if (!isLifetimeBorrowed(tok, mSettings))
continue;
if (tokvalue->exprId() == tok->exprId() && !(tok->variable() && tok->variable()->isArray()) &&
!astIsContainerView(tok->astParent()))
continue;
if ((tokvalue->variable() && !isEscapedReference(tokvalue->variable()) &&
isInScope(tokvalue->variable()->nameToken(), scope)) ||
isDeadTemporary(mTokenizer->isCPP(), tokvalue, nullptr, &mSettings->library)) {
errorReturnDanglingLifetime(tok, &val);
break;
}
} else if (tokvalue->variable() && isDeadScope(tokvalue->variable()->nameToken(), tok->scope())) {
errorInvalidLifetime(tok, &val);
break;
} else if (!tokvalue->variable() &&
isDeadTemporary(mTokenizer->isCPP(), tokvalue, tok, &mSettings->library)) {
errorDanglingTemporaryLifetime(tok, &val, tokvalue);
break;
}
}
if (tokvalue->variable() && (isInScope(tokvalue->variable()->nameToken(), tok->scope()) ||
(val.isSubFunctionLifetimeValue() && isDanglingSubFunction(tokvalue, tok)))) {
const Variable * var = nullptr;
const Token * tok2 = tok;
if (Token::simpleMatch(tok->astParent(), "=")) {
if (astIsRHS(tok)) {
var = getParentVar(tok->astParent()->astOperand1());
tok2 = tok->astParent()->astOperand1();
}
} else if (tok->variable() && tok->variable()->declarationId() == tok->varId()) {
var = tok->variable();
}
if (!isLifetimeBorrowed(tok, mSettings))
continue;
const Token* nextTok = nextAfterAstRightmostLeaf(tok->astTop());
if (!nextTok)
nextTok = tok->next();
if (var && !var->isLocal() && !var->isArgument() &&
!isVariableChanged(nextTok,
tok->scope()->bodyEnd,
var->declarationId(),
var->isGlobal(),
mSettings,
mTokenizer->isCPP())) {
errorDanglngLifetime(tok2, &val);
break;
}
}
}
}
const Token *lambdaEndToken = findLambdaEndToken(tok);
if (lambdaEndToken) {
checkVarLifetimeScope(lambdaEndToken->link(), lambdaEndToken);
tok = lambdaEndToken;
}
if (tok->str() == "{" && tok->scope()) {
// Check functions in local classes
if (tok->scope()->type == Scope::eClass ||
tok->scope()->type == Scope::eStruct ||
tok->scope()->type == Scope::eUnion) {
for (const Function& f:tok->scope()->functionList) {
if (f.functionScope)
checkVarLifetimeScope(f.functionScope->bodyStart, f.functionScope->bodyEnd);
}
tok = tok->link();
}
}
}
}
void CheckAutoVariables::checkVarLifetime()
{
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
if (!scope->function)
continue;
checkVarLifetimeScope(scope->bodyStart, scope->bodyEnd);
}
}
void CheckAutoVariables::errorReturnDanglingLifetime(const Token *tok, const ValueFlow::Value *val)
{
const bool inconclusive = val ? val->isInconclusive() : false;
ErrorPath errorPath = val ? val->errorPath : ErrorPath();
std::string msg = "Returning " + lifetimeMessage(tok, val, errorPath);
errorPath.emplace_back(tok, "");
reportError(errorPath, Severity::error, "returnDanglingLifetime", msg + " that will be invalid when returning.", CWE562, inconclusive ? Certainty::inconclusive : Certainty::normal);
}
void CheckAutoVariables::errorInvalidLifetime(const Token *tok, const ValueFlow::Value* val)
{
const bool inconclusive = val ? val->isInconclusive() : false;
ErrorPath errorPath = val ? val->errorPath : ErrorPath();
std::string msg = "Using " + lifetimeMessage(tok, val, errorPath);
errorPath.emplace_back(tok, "");
reportError(errorPath, Severity::error, "invalidLifetime", msg + " that is out of scope.", CWE562, inconclusive ? Certainty::inconclusive : Certainty::normal);
}
void CheckAutoVariables::errorDanglingTemporaryLifetime(const Token* tok, const ValueFlow::Value* val, const Token* tempTok)
{
const bool inconclusive = val ? val->isInconclusive() : false;
ErrorPath errorPath = val ? val->errorPath : ErrorPath();
std::string msg = "Using " + lifetimeMessage(tok, val, errorPath);
errorPath.emplace_back(tempTok, "Temporary created here.");
errorPath.emplace_back(tok, "");
reportError(errorPath,
Severity::error,
"danglingTemporaryLifetime",
msg + " that is a temporary.",
CWE562,
inconclusive ? Certainty::inconclusive : Certainty::normal);
}
void CheckAutoVariables::errorDanglngLifetime(const Token *tok, const ValueFlow::Value *val)
{
const bool inconclusive = val ? val->isInconclusive() : false;
ErrorPath errorPath = val ? val->errorPath : ErrorPath();
std::string tokName = tok ? tok->expressionString() : "x";
std::string msg = "Non-local variable '" + tokName + "' will use " + lifetimeMessage(tok, val, errorPath);
errorPath.emplace_back(tok, "");
reportError(errorPath, Severity::error, "danglingLifetime", msg + ".", CWE562, inconclusive ? Certainty::inconclusive : Certainty::normal);
}
void CheckAutoVariables::errorDanglingTempReference(const Token* tok, ErrorPath errorPath, bool inconclusive)
{
errorPath.emplace_back(tok, "");
reportError(
errorPath, Severity::error, "danglingTempReference", "Using reference to dangling temporary.", CWE562, inconclusive ? Certainty::inconclusive : Certainty::normal);
}
void CheckAutoVariables::errorReturnReference(const Token* tok, ErrorPath errorPath, bool inconclusive)
{
errorPath.emplace_back(tok, "");
reportError(
errorPath, Severity::error, "returnReference", "Reference to local variable returned.", CWE562, inconclusive ? Certainty::inconclusive : Certainty::normal);
}
void CheckAutoVariables::errorDanglingReference(const Token *tok, const Variable *var, ErrorPath errorPath)
{
std::string tokName = tok ? tok->str() : "x";
std::string varName = var ? var->name() : "y";
std::string msg = "Non-local reference variable '" + tokName + "' to local variable '" + varName + "'";
errorPath.emplace_back(tok, "");
reportError(errorPath, Severity::error, "danglingReference", msg, CWE562, Certainty::normal);
}
void CheckAutoVariables::errorReturnTempReference(const Token* tok, ErrorPath errorPath, bool inconclusive)
{
errorPath.emplace_back(tok, "");
reportError(
errorPath, Severity::error, "returnTempReference", "Reference to temporary returned.", CWE562, inconclusive ? Certainty::inconclusive : Certainty::normal);
}
void CheckAutoVariables::errorInvalidDeallocation(const Token *tok, const ValueFlow::Value *val)
{
const Variable *var = val ? val->tokvalue->variable() : (tok ? tok->variable() : nullptr);
std::string type = "auto-variable";
if (tok && tok->tokType() == Token::eString)
type = "string literal";
else if (val && val->tokvalue->tokType() == Token::eString)
type = "pointer pointing to a string literal";
else if (var) {
if (var->isGlobal())
type = "global variable";
else if (var->isStatic())
type = "static variable";
}
if (val)
type += " (" + val->tokvalue->str() + ")";
reportError(getErrorPath(tok, val, "Deallocating memory that was not dynamically allocated"),
Severity::error,
"autovarInvalidDeallocation",
"Deallocation of an " + type + " results in undefined behaviour.\n"
"The deallocation of an " + type + " results in undefined behaviour. You should only free memory "
"that has been allocated dynamically.", CWE590, Certainty::normal);
}
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