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cppcheck/lib/checkstl.cpp

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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2023 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/>.
*/
#include "checkstl.h"
#include "astutils.h"
#include "errortypes.h"
#include "library.h"
#include "mathlib.h"
#include "pathanalysis.h"
#include "settings.h"
#include "standards.h"
#include "symboldatabase.h"
#include "token.h"
#include "tokenize.h"
#include "utils.h"
#include "valueflow.h"
#include "checknullpointer.h"
#include <algorithm>
#include <cassert>
#include <iterator>
#include <list>
#include <map>
#include <set>
#include <sstream>
#include <tuple>
#include <unordered_map>
#include <utility>
#include <vector>
// Register this check class (by creating a static instance of it)
namespace {
CheckStl instance;
}
// CWE IDs used:
static const CWE CWE398(398U); // Indicator of Poor Code Quality
static const CWE CWE597(597U); // Use of Wrong Operator in String Comparison
static const CWE CWE628(628U); // Function Call with Incorrectly Specified Arguments
static const CWE CWE664(664U); // Improper Control of a Resource Through its Lifetime
static const CWE CWE667(667U); // Improper Locking
static const CWE CWE704(704U); // Incorrect Type Conversion or Cast
static const CWE CWE762(762U); // Mismatched Memory Management Routines
static const CWE CWE786(786U); // Access of Memory Location Before Start of Buffer
static const CWE CWE788(788U); // Access of Memory Location After End of Buffer
static const CWE CWE825(825U); // Expired Pointer Dereference
static const CWE CWE833(833U); // Deadlock
static const CWE CWE834(834U); // Excessive Iteration
static bool isElementAccessYield(Library::Container::Yield yield)
{
return contains({Library::Container::Yield::ITEM, Library::Container::Yield::AT_INDEX}, yield);
}
static bool containerAppendsElement(const Library::Container* container, const Token* parent)
{
if (Token::Match(parent, ". %name% (")) {
const Library::Container::Action action = container->getAction(parent->strAt(1));
if (contains({Library::Container::Action::INSERT,
Library::Container::Action::CHANGE,
Library::Container::Action::CHANGE_INTERNAL,
Library::Container::Action::PUSH,
Library::Container::Action::RESIZE},
action))
return true;
}
return false;
}
static bool containerYieldsElement(const Library::Container* container, const Token* parent)
{
if (Token::Match(parent, ". %name% (")) {
const Library::Container::Yield yield = container->getYield(parent->strAt(1));
if (isElementAccessYield(yield))
return true;
}
return false;
}
static bool containerPopsElement(const Library::Container* container, const Token* parent)
{
if (Token::Match(parent, ". %name% (")) {
const Library::Container::Action action = container->getAction(parent->strAt(1));
if (contains({ Library::Container::Action::POP }, action))
return true;
}
return false;
}
static const Token* getContainerIndex(const Library::Container* container, const Token* parent)
{
if (Token::Match(parent, ". %name% (")) {
const Library::Container::Yield yield = container->getYield(parent->strAt(1));
if (yield == Library::Container::Yield::AT_INDEX && !Token::simpleMatch(parent->tokAt(2), "( )"))
return parent->tokAt(2)->astOperand2();
}
if (!container->arrayLike_indexOp && !container->stdStringLike)
return nullptr;
if (Token::simpleMatch(parent, "["))
return parent->astOperand2();
return nullptr;
}
static const Token* getContainerFromSize(const Library::Container* container, const Token* tok)
{
if (!tok)
return nullptr;
if (Token::Match(tok->tokAt(-2), ". %name% (")) {
const Library::Container::Yield yield = container->getYield(tok->strAt(-1));
if (yield == Library::Container::Yield::SIZE)
return tok->tokAt(-2)->astOperand1();
}
return nullptr;
}
void CheckStl::outOfBounds()
{
logChecker("CheckStl::outOfBounds");
for (const Scope *function : mTokenizer->getSymbolDatabase()->functionScopes) {
for (const Token *tok = function->bodyStart; tok != function->bodyEnd; tok = tok->next()) {
const Library::Container *container = getLibraryContainer(tok);
if (!container || container->stdAssociativeLike)
continue;
const Token * parent = astParentSkipParens(tok);
const Token* accessTok = parent;
if (Token::simpleMatch(accessTok, ".") && Token::simpleMatch(accessTok->astParent(), "("))
accessTok = accessTok->astParent();
if (astIsIterator(accessTok) && Token::simpleMatch(accessTok->astParent(), "+"))
accessTok = accessTok->astParent();
const Token* indexTok = getContainerIndex(container, parent);
if (indexTok == tok)
continue;
for (const ValueFlow::Value &value : tok->values()) {
if (!value.isContainerSizeValue())
continue;
if (value.isImpossible())
continue;
if (value.isInconclusive() && !mSettings->certainty.isEnabled(Certainty::inconclusive))
continue;
if (!value.errorSeverity() && !mSettings->severity.isEnabled(Severity::warning))
continue;
if (value.intvalue == 0 && (indexTok ||
(containerYieldsElement(container, parent) && !containerAppendsElement(container, parent)) ||
containerPopsElement(container, parent))) {
std::string indexExpr;
if (indexTok && !indexTok->hasKnownValue())
indexExpr = indexTok->expressionString();
outOfBoundsError(accessTok, tok->expressionString(), &value, indexExpr, nullptr);
continue;
}
if (indexTok) {
std::vector<ValueFlow::Value> indexValues =
ValueFlow::isOutOfBounds(value, indexTok, mSettings->severity.isEnabled(Severity::warning));
if (!indexValues.empty()) {
outOfBoundsError(
accessTok, tok->expressionString(), &value, indexTok->expressionString(), &indexValues.front());
continue;
}
}
}
if (indexTok && !indexTok->hasKnownIntValue()) {
const ValueFlow::Value* value =
ValueFlow::findValue(indexTok->values(), mSettings, [&](const ValueFlow::Value& v) {
if (!v.isSymbolicValue())
return false;
if (v.isImpossible())
return false;
if (v.intvalue < 0)
return false;
const Token* sizeTok = v.tokvalue;
if (sizeTok && sizeTok->isCast())
sizeTok = sizeTok->astOperand2() ? sizeTok->astOperand2() : sizeTok->astOperand1();
const Token* containerTok = getContainerFromSize(container, sizeTok);
if (!containerTok)
return false;
return containerTok->exprId() == tok->exprId();
});
if (!value)
continue;
outOfBoundsError(accessTok, tok->expressionString(), nullptr, indexTok->expressionString(), value);
}
}
}
}
static std::string indexValueString(const ValueFlow::Value& indexValue, const std::string& containerName = emptyString)
{
if (indexValue.isIteratorStartValue())
return "at position " + std::to_string(indexValue.intvalue) + " from the beginning";
if (indexValue.isIteratorEndValue())
return "at position " + std::to_string(-indexValue.intvalue) + " from the end";
std::string indexString = std::to_string(indexValue.intvalue);
if (indexValue.isSymbolicValue()) {
indexString = containerName + ".size()";
if (indexValue.intvalue != 0)
indexString += "+" + std::to_string(indexValue.intvalue);
}
if (indexValue.bound == ValueFlow::Value::Bound::Lower)
return "greater or equal to " + indexString;
return indexString;
}
void CheckStl::outOfBoundsError(const Token *tok, const std::string &containerName, const ValueFlow::Value *containerSize, const std::string &index, const ValueFlow::Value *indexValue)
{
// Do not warn if both the container size and index value are possible
if (containerSize && indexValue && containerSize->isPossible() && indexValue->isPossible())
return;
const std::string expression = tok ? tok->expressionString() : (containerName+"[x]");
std::string errmsg;
if (!containerSize) {
if (indexValue && indexValue->condition)
errmsg = ValueFlow::eitherTheConditionIsRedundant(indexValue->condition) + " or '" + index +
"' can have the value " + indexValueString(*indexValue, containerName) + ". Expression '" +
expression + "' cause access out of bounds.";
else
errmsg = "Out of bounds access in expression '" + expression + "'";
} else if (containerSize->intvalue == 0) {
if (containerSize->condition)
errmsg = ValueFlow::eitherTheConditionIsRedundant(containerSize->condition) + " or expression '" + expression + "' cause access out of bounds.";
else if (indexValue == nullptr && !index.empty())
errmsg = "Out of bounds access in expression '" + expression + "' because '$symbol' is empty and '" + index + "' may be non-zero.";
else
errmsg = "Out of bounds access in expression '" + expression + "' because '$symbol' is empty.";
} else if (indexValue) {
if (containerSize->condition)
errmsg = ValueFlow::eitherTheConditionIsRedundant(containerSize->condition) + " or $symbol size can be " + std::to_string(containerSize->intvalue) + ". Expression '" + expression + "' cause access out of bounds.";
else if (indexValue->condition)
errmsg = ValueFlow::eitherTheConditionIsRedundant(indexValue->condition) + " or '" + index + "' can have the value " + indexValueString(*indexValue) + ". Expression '" + expression + "' cause access out of bounds.";
else
errmsg = "Out of bounds access in '" + expression + "', if '$symbol' size is " + std::to_string(containerSize->intvalue) + " and '" + index + "' is " + indexValueString(*indexValue);
} else {
// should not happen
return;
}
ErrorPath errorPath;
if (!indexValue)
errorPath = getErrorPath(tok, containerSize, "Access out of bounds");
else {
ErrorPath errorPath1 = getErrorPath(tok, containerSize, "Access out of bounds");
ErrorPath errorPath2 = getErrorPath(tok, indexValue, "Access out of bounds");
if (errorPath1.size() <= 1)
errorPath = errorPath2;
else if (errorPath2.size() <= 1)
errorPath = errorPath1;
else {
errorPath = errorPath1;
errorPath.splice(errorPath.end(), errorPath2);
}
}
reportError(errorPath,
(containerSize && !containerSize->errorSeverity()) || (indexValue && !indexValue->errorSeverity()) ? Severity::warning : Severity::error,
"containerOutOfBounds",
"$symbol:" + containerName +"\n" + errmsg,
CWE398,
(containerSize && containerSize->isInconclusive()) || (indexValue && indexValue->isInconclusive()) ? Certainty::inconclusive : Certainty::normal);
}
bool CheckStl::isContainerSize(const Token *containerToken, const Token *expr) const
{
if (!Token::simpleMatch(expr, "( )"))
return false;
if (!Token::Match(expr->astOperand1(), ". %name% ("))
return false;
if (!isSameExpression(mTokenizer->isCPP(), false, containerToken, expr->astOperand1()->astOperand1(), mSettings->library, false, false))
return false;
return containerToken->valueType()->container->getYield(expr->previous()->str()) == Library::Container::Yield::SIZE;
}
bool CheckStl::isContainerSizeGE(const Token * containerToken, const Token *expr) const
{
if (!expr)
return false;
if (isContainerSize(containerToken, expr))
return true;
if (expr->str() == "*") {
const Token *mul;
if (isContainerSize(containerToken, expr->astOperand1()))
mul = expr->astOperand2();
else if (isContainerSize(containerToken, expr->astOperand2()))
mul = expr->astOperand1();
else
return false;
return mul && (!mul->hasKnownIntValue() || mul->values().front().intvalue != 0);
}
if (expr->str() == "+") {
const Token *op;
if (isContainerSize(containerToken, expr->astOperand1()))
op = expr->astOperand2();
else if (isContainerSize(containerToken, expr->astOperand2()))
op = expr->astOperand1();
else
return false;
return op && op->getValueGE(0, mSettings);
}
return false;
}
void CheckStl::outOfBoundsIndexExpression()
{
logChecker("CheckStl::outOfBoundsIndexExpression");
for (const Scope *function : mTokenizer->getSymbolDatabase()->functionScopes) {
for (const Token *tok = function->bodyStart; tok != function->bodyEnd; tok = tok->next()) {
if (!tok->isName() || !tok->valueType())
continue;
const Library::Container *container = tok->valueType()->container;
if (!container)
continue;
if (!container->arrayLike_indexOp && !container->stdStringLike)
continue;
if (!Token::Match(tok, "%name% ["))
continue;
if (isContainerSizeGE(tok, tok->next()->astOperand2()))
outOfBoundsIndexExpressionError(tok, tok->next()->astOperand2());
}
}
}
void CheckStl::outOfBoundsIndexExpressionError(const Token *tok, const Token *index)
{
const std::string varname = tok ? tok->str() : std::string("var");
const std::string i = index ? index->expressionString() : std::string(varname + ".size()");
std::string errmsg = "Out of bounds access of $symbol, index '" + i + "' is out of bounds.";
reportError(tok,
Severity::error,
"containerOutOfBoundsIndexExpression",
"$symbol:" + varname +"\n" + errmsg,
CWE398,
Certainty::normal);
}
// Error message for bad iterator usage..
void CheckStl::invalidIteratorError(const Token *tok, const std::string &iteratorName)
{
reportError(tok, Severity::error, "invalidIterator1", "$symbol:"+iteratorName+"\nInvalid iterator: $symbol", CWE664, Certainty::normal);
}
void CheckStl::iteratorsError(const Token* tok, const std::string& containerName1, const std::string& containerName2)
{
reportError(tok, Severity::error, "iterators1",
"$symbol:" + containerName1 + "\n"
"$symbol:" + containerName2 + "\n"
"Same iterator is used with different containers '" + containerName1 + "' and '" + containerName2 + "'.", CWE664, Certainty::normal);
}
void CheckStl::iteratorsError(const Token* tok, const Token* containerTok, const std::string& containerName1, const std::string& containerName2)
{
std::list<const Token*> callstack = { tok, containerTok };
reportError(callstack, Severity::error, "iterators2",
"$symbol:" + containerName1 + "\n"
"$symbol:" + containerName2 + "\n"
"Same iterator is used with different containers '" + containerName1 + "' and '" + containerName2 + "'.", CWE664, Certainty::normal);
}
void CheckStl::iteratorsError(const Token* tok, const Token* containerTok, const std::string& containerName)
{
std::list<const Token*> callstack = { tok, containerTok };
reportError(callstack,
Severity::error,
"iterators3",
"$symbol:" + containerName +
"\n"
"Same iterator is used with containers '$symbol' that are temporaries or defined in different scopes.",
CWE664,
Certainty::normal);
}
// Error message used when dereferencing an iterator that has been erased..
void CheckStl::dereferenceErasedError(const Token *erased, const Token* deref, const std::string &itername, bool inconclusive)
{
if (erased) {
std::list<const Token*> callstack = { deref, erased };
reportError(callstack, Severity::error, "eraseDereference",
"$symbol:" + itername + "\n"
"Iterator '$symbol' used after element has been erased.\n"
"The iterator '$symbol' is invalid after the element it pointed to has been erased. "
"Dereferencing or comparing it with another iterator is invalid operation.", CWE664, inconclusive ? Certainty::inconclusive : Certainty::normal);
} else {
reportError(deref, Severity::error, "eraseDereference",
"$symbol:" + itername + "\n"
"Invalid iterator '$symbol' used.\n"
"The iterator '$symbol' is invalid before being assigned. "
"Dereferencing or comparing it with another iterator is invalid operation.", CWE664, inconclusive ? Certainty::inconclusive : Certainty::normal);
}
}
static const Token *skipMembers(const Token *tok)
{
while (Token::Match(tok, "%name% ."))
tok = tok->tokAt(2);
return tok;
}
static bool isIterator(const Variable *var, bool& inconclusiveType)
{
// Check that its an iterator
if (!var || !var->isLocal() || !Token::Match(var->typeEndToken(), "iterator|const_iterator|reverse_iterator|const_reverse_iterator|auto"))
return false;
inconclusiveType = false;
if (var->typeEndToken()->str() == "auto")
return (var->nameToken()->valueType() && var->nameToken()->valueType()->type == ValueType::Type::ITERATOR);
if (var->type()) { // If it is defined, ensure that it is defined like an iterator
// look for operator* and operator++
const Function* end = var->type()->getFunction("operator*");
const Function* incOperator = var->type()->getFunction("operator++");
if (!end || end->argCount() > 0 || !incOperator)
return false;
inconclusiveType = true; // heuristics only
}
return true;
}
static std::string getContainerName(const Token *containerToken)
{
if (!containerToken)
return std::string();
std::string ret(containerToken->str());
for (const Token *nametok = containerToken; nametok; nametok = nametok->tokAt(-2)) {
if (!Token::Match(nametok->tokAt(-2), "%name% ."))
break;
ret = nametok->strAt(-2) + '.' + ret;
}
return ret;
}
static bool isVector(const Token* tok)
{
if (!tok)
return false;
const Variable *var = tok->variable();
const Token *decltok = var ? var->typeStartToken() : nullptr;
return Token::simpleMatch(decltok, "std :: vector");
}
void CheckStl::iterators()
{
logChecker("CheckStl::iterators");
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
// Filling map of iterators id and their scope begin
std::map<int, const Token*> iteratorScopeBeginInfo;
for (const Variable* var : symbolDatabase->variableList()) {
bool inconclusiveType=false;
if (!isIterator(var, inconclusiveType))
continue;
const int iteratorId = var->declarationId();
if (iteratorId != 0)
iteratorScopeBeginInfo[iteratorId] = var->nameToken();
}
for (const Variable* var : symbolDatabase->variableList()) {
bool inconclusiveType=false;
if (!isIterator(var, inconclusiveType))
continue;
if (inconclusiveType && !mSettings->certainty.isEnabled(Certainty::inconclusive))
continue;
const int iteratorId = var->declarationId();
// the validIterator flag says if the iterator has a valid value or not
bool validIterator = Token::Match(var->nameToken()->next(), "[(=:{]");
const Scope* invalidationScope = nullptr;
// The container this iterator can be used with
const Token* containerToken = nullptr;
const Scope* containerAssignScope = nullptr;
// When "validatingToken" is reached the validIterator is set to true
const Token* validatingToken = nullptr;
const Token* eraseToken = nullptr;
// Scan through the rest of the code and see if the iterator is
// used against other containers.
for (const Token *tok2 = var->nameToken(); tok2 && tok2 != var->scope()->bodyEnd; tok2 = tok2->next()) {
if (invalidationScope && tok2 == invalidationScope->bodyEnd)
validIterator = true; // Assume that the iterator becomes valid again
if (containerAssignScope && tok2 == containerAssignScope->bodyEnd)
containerToken = nullptr; // We don't know which containers might be used with the iterator
if (tok2 == validatingToken) {
validIterator = true;
eraseToken = nullptr;
invalidationScope = nullptr;
}
// Is the iterator used in a insert/erase operation?
if (Token::Match(tok2, "%name% . insert|erase ( *| %varid% )|,", iteratorId) && !isVector(tok2)) {
const Token* itTok = tok2->tokAt(4);
if (itTok->str() == "*") {
if (tok2->strAt(2) == "insert")
continue;
itTok = itTok->next();
}
// It is bad to insert/erase an invalid iterator
if (!validIterator)
invalidIteratorError(tok2, itTok->str());
// If insert/erase is used on different container then
// report an error
if (containerToken && tok2->varId() != containerToken->varId()) {
// skip error message if container is a set..
const Variable *variableInfo = tok2->variable();
const Token *decltok = variableInfo ? variableInfo->typeStartToken() : nullptr;
if (Token::simpleMatch(decltok, "std :: set"))
continue; // No warning
// skip error message if the iterator is erased/inserted by value
if (itTok->previous()->str() == "*")
continue;
// inserting iterator range..
if (tok2->strAt(2) == "insert") {
const Token *par2 = itTok->nextArgument();
if (!par2 || par2->nextArgument())
continue;
while (par2->str() != ")") {
if (par2->varId() == containerToken->varId())
break;
bool inconclusiveType2=false;
if (isIterator(par2->variable(), inconclusiveType2))
break; // TODO: check if iterator points at same container
if (par2->str() == "(")
par2 = par2->link();
par2 = par2->next();
}
if (par2->str() != ")")
continue;
}
// Not different containers if a reference is used..
if (containerToken && containerToken->variable() && containerToken->variable()->isReference()) {
const Token *nameToken = containerToken->variable()->nameToken();
if (Token::Match(nameToken, "%name% =")) {
const Token *name1 = nameToken->tokAt(2);
const Token *name2 = tok2;
while (Token::Match(name1, "%name%|.|::") && name2 && name1->str() == name2->str()) {
name1 = name1->next();
name2 = name2->next();
}
if (!Token::simpleMatch(name1, ";") || !Token::Match(name2, "[;,()=]"))
continue;
}
}
// Show error message, mismatching iterator is used.
iteratorsError(tok2, getContainerName(containerToken), getContainerName(tok2));
}
// invalidate the iterator if it is erased
else if (tok2->strAt(2) == "erase" && (tok2->strAt(4) != "*" || (containerToken && tok2->varId() == containerToken->varId()))) {
validIterator = false;
eraseToken = tok2;
invalidationScope = tok2->scope();
}
// skip the operation
tok2 = itTok->next();
}
// it = foo.erase(..
// taking the result of an erase is ok
else if (Token::Match(tok2, "%varid% = %name% .", iteratorId) &&
Token::simpleMatch(skipMembers(tok2->tokAt(2)), "erase (")) {
// the returned iterator is valid
validatingToken = skipMembers(tok2->tokAt(2))->linkAt(1);
tok2 = validatingToken->link();
}
// Reassign the iterator
else if (Token::Match(tok2, "%varid% = %name% .", iteratorId) &&
Token::Match(skipMembers(tok2->tokAt(2)), "begin|rbegin|cbegin|crbegin|find (")) {
validatingToken = skipMembers(tok2->tokAt(2))->linkAt(1);
containerToken = skipMembers(tok2->tokAt(2))->tokAt(-2);
if (containerToken->varId() == 0 || Token::simpleMatch(validatingToken, ") ."))
containerToken = nullptr;
containerAssignScope = tok2->scope();
// skip ahead
tok2 = validatingToken->link();
}
// Reassign the iterator
else if (Token::Match(tok2, "%varid% =", iteratorId)) {
break;
}
// Passing iterator to function. Iterator might be initialized
else if (Token::Match(tok2, "%varid% ,|)", iteratorId)) {
validIterator = true;
}
// Dereferencing invalid iterator?
else if (!validIterator && Token::Match(tok2, "* %varid%", iteratorId)) {
dereferenceErasedError(eraseToken, tok2, tok2->strAt(1), inconclusiveType);
tok2 = tok2->next();
} else if (!validIterator && Token::Match(tok2, "%varid% . %name%", iteratorId)) {
dereferenceErasedError(eraseToken, tok2, tok2->str(), inconclusiveType);
tok2 = tok2->tokAt(2);
}
// bailout handling. Assume that the iterator becomes valid if we see return/break.
// TODO: better handling
else if (tok2->scope() == invalidationScope && Token::Match(tok2, "return|break|continue")) {
validatingToken = Token::findsimplematch(tok2->next(), ";");
}
// bailout handling. Assume that the iterator becomes valid if we see else.
// TODO: better handling
else if (tok2->str() == "else") {
validIterator = true;
}
}
}
}
void CheckStl::mismatchingContainerIteratorError(const Token* tok, const Token* iterTok)
{
const std::string container(tok ? tok->expressionString() : std::string("v1"));
const std::string iter(iterTok ? iterTok->expressionString() : std::string("it"));
reportError(tok,
Severity::error,
"mismatchingContainerIterator",
"Iterator '" + iter + "' from different container '" + container + "' are used together.",
CWE664,
Certainty::normal);
}
// Error message for bad iterator usage..
void CheckStl::mismatchingContainersError(const Token* tok1, const Token* tok2)
{
const std::string expr1(tok1 ? tok1->expressionString() : std::string("v1"));
const std::string expr2(tok2 ? tok2->expressionString() : std::string("v2"));
reportError(tok1,
Severity::error,
"mismatchingContainers",
"Iterators of different containers '" + expr1 + "' and '" + expr2 + "' are used together.",
CWE664,
Certainty::normal);
}
void CheckStl::mismatchingContainerExpressionError(const Token *tok1, const Token *tok2)
{
const std::string expr1(tok1 ? tok1->expressionString() : std::string("v1"));
const std::string expr2(tok2 ? tok2->expressionString() : std::string("v2"));
reportError(tok1, Severity::warning, "mismatchingContainerExpression",
"Iterators to containers from different expressions '" +
expr1 + "' and '" + expr2 + "' are used together.", CWE664, Certainty::normal);
}
void CheckStl::sameIteratorExpressionError(const Token *tok)
{
reportError(tok, Severity::style, "sameIteratorExpression", "Same iterators expression are used for algorithm.", CWE664, Certainty::normal);
}
static const Token* getAddressContainer(const Token* tok)
{
if (Token::simpleMatch(tok, "[") && tok->astOperand1())
return tok->astOperand1();
return tok;
}
static bool isSameIteratorContainerExpression(const Token* tok1,
const Token* tok2,
const Library& library,
ValueFlow::Value::LifetimeKind kind = ValueFlow::Value::LifetimeKind::Iterator)
{
if (isSameExpression(true, false, tok1, tok2, library, false, false)) {
return !astIsContainerOwned(tok1) || !isTemporary(true, tok1, &library);
}
if (kind == ValueFlow::Value::LifetimeKind::Address) {
return isSameExpression(true, false, getAddressContainer(tok1), getAddressContainer(tok2), library, false, false);
}
return false;
}
static ValueFlow::Value getLifetimeIteratorValue(const Token* tok, MathLib::bigint path = 0)
{
std::vector<ValueFlow::Value> values = ValueFlow::getLifetimeObjValues(tok, false, path);
auto it = std::find_if(values.cbegin(), values.cend(), [](const ValueFlow::Value& v) {
return v.lifetimeKind == ValueFlow::Value::LifetimeKind::Iterator;
});
if (it != values.end())
return *it;
if (values.size() == 1)
return values.front();
return ValueFlow::Value{};
}
bool CheckStl::checkIteratorPair(const Token* tok1, const Token* tok2)
{
if (!tok1)
return false;
if (!tok2)
return false;
ValueFlow::Value val1 = getLifetimeIteratorValue(tok1);
ValueFlow::Value val2 = getLifetimeIteratorValue(tok2);
if (val1.tokvalue && val2.tokvalue && val1.lifetimeKind == val2.lifetimeKind) {
if (val1.lifetimeKind == ValueFlow::Value::LifetimeKind::Lambda)
return false;
if (tok1->astParent() == tok2->astParent() && Token::Match(tok1->astParent(), "%comp%|-")) {
if (val1.lifetimeKind == ValueFlow::Value::LifetimeKind::Address)
return false;
if (val1.lifetimeKind == ValueFlow::Value::LifetimeKind::Object &&
(!astIsContainer(val1.tokvalue) || !astIsContainer(val2.tokvalue)))
return false;
}
if (isSameIteratorContainerExpression(val1.tokvalue, val2.tokvalue, mSettings->library, val1.lifetimeKind))
return false;
if (val1.tokvalue->expressionString() == val2.tokvalue->expressionString())
iteratorsError(tok1, val1.tokvalue, val1.tokvalue->expressionString());
else
mismatchingContainersError(val1.tokvalue, val2.tokvalue);
return true;
}
if (Token::Match(tok1->astParent(), "%comp%|-")) {
if (astIsIntegral(tok1, true) || astIsIntegral(tok2, true) ||
astIsFloat(tok1, true) || astIsFloat(tok2, true))
return false;
}
const Token* iter1 = getIteratorExpression(tok1);
const Token* iter2 = getIteratorExpression(tok2);
if (iter1 && iter2 && !isSameIteratorContainerExpression(iter1, iter2, mSettings->library)) {
mismatchingContainerExpressionError(iter1, iter2);
return true;
}
return false;
}
namespace {
struct ArgIteratorInfo {
const Token* tok;
const Library::ArgumentChecks::IteratorInfo* info;
};
}
void CheckStl::mismatchingContainers()
{
logChecker("CheckStl::misMatchingContainers");
// Check if different containers are used in various calls of standard functions
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (Token::Match(tok, "%comp%|-")) {
if (checkIteratorPair(tok->astOperand1(), tok->astOperand2()))
continue;
}
if (!Token::Match(tok, "%name% ( !!)"))
continue;
const Token * const ftok = tok;
const std::vector<const Token *> args = getArguments(ftok);
if (args.size() < 2)
continue;
// Group args together by container
std::map<int, std::vector<ArgIteratorInfo>> containers;
for (int argnr = 1; argnr <= args.size(); ++argnr) {
const Library::ArgumentChecks::IteratorInfo *i = mSettings->library.getArgIteratorInfo(ftok, argnr);
if (!i)
continue;
const Token * const argTok = args[argnr - 1];
containers[i->container].emplace_back(ArgIteratorInfo{argTok, i});
}
// Lambda is used to escape the nested loops
[&] {
for (const auto& p : containers)
{
const std::vector<ArgIteratorInfo>& cargs = p.second;
for (ArgIteratorInfo iter1 : cargs) {
for (ArgIteratorInfo iter2 : cargs) {
if (iter1.tok == iter2.tok)
continue;
if (iter1.info->first && iter2.info->last &&
isSameExpression(true, false, iter1.tok, iter2.tok, mSettings->library, false, false))
sameIteratorExpressionError(iter1.tok);
if (checkIteratorPair(iter1.tok, iter2.tok))
return;
}
}
}
}();
}
}
for (const Variable *var : symbolDatabase->variableList()) {
if (var && var->isStlStringType() && Token::Match(var->nameToken(), "%var% (") &&
Token::Match(var->nameToken()->tokAt(2), "%name% . begin|cbegin|rbegin|crbegin ( ) , %name% . end|cend|rend|crend ( ) ,|)")) {
if (var->nameToken()->strAt(2) != var->nameToken()->strAt(8)) {
mismatchingContainersError(var->nameToken(), var->nameToken()->tokAt(2));
}
}
}
}
void CheckStl::mismatchingContainerIterator()
{
logChecker("CheckStl::misMatchingContainerIterator");
// Check if different containers are used in various calls of standard functions
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (!astIsContainer(tok))
continue;
if (!astIsLHS(tok))
continue;
if (!Token::Match(tok->astParent(), ". %name% ( !!)"))
continue;
const Token* const ftok = tok->astParent()->next();
const std::vector<const Token *> args = getArguments(ftok);
const Library::Container * c = tok->valueType()->container;
const Library::Container::Action action = c->getAction(tok->strAt(2));
const Token* iterTok = nullptr;
if (action == Library::Container::Action::INSERT && args.size() == 2) {
// Skip if iterator pair
if (astIsIterator(args.back()))
continue;
if (!astIsIterator(args.front()))
continue;
iterTok = args.front();
} else if (action == Library::Container::Action::ERASE) {
if (!astIsIterator(args.front()))
continue;
iterTok = args.front();
} else {
continue;
}
ValueFlow::Value val = getLifetimeIteratorValue(iterTok);
if (!val.tokvalue)
continue;
if (val.lifetimeKind != ValueFlow::Value::LifetimeKind::Iterator)
continue;
if (isSameIteratorContainerExpression(tok, val.tokvalue, mSettings->library))
continue;
mismatchingContainerIteratorError(tok, iterTok);
}
}
}
static const Token* getInvalidMethod(const Token* tok)
{
if (!astIsLHS(tok))
return nullptr;
if (Token::Match(tok->astParent(), ". assign|clear|swap"))
return tok->astParent()->next();
if (Token::Match(tok->astParent(), "%assign%"))
return tok->astParent();
const Token* ftok = nullptr;
if (Token::Match(tok->astParent(), ". %name% ("))
ftok = tok->astParent()->next();
if (!ftok)
return nullptr;
if (const Library::Container * c = tok->valueType()->container) {
const Library::Container::Action action = c->getAction(ftok->str());
if (c->unstableErase) {
if (action == Library::Container::Action::ERASE)
return ftok;
}
if (c->unstableInsert) {
if (action == Library::Container::Action::RESIZE)
return ftok;
if (action == Library::Container::Action::CLEAR)
return ftok;
if (action == Library::Container::Action::PUSH)
return ftok;
if (action == Library::Container::Action::POP)
return ftok;
if (action == Library::Container::Action::INSERT)
return ftok;
if (action == Library::Container::Action::CHANGE)
return ftok;
if (action == Library::Container::Action::CHANGE_INTERNAL)
return ftok;
if (Token::Match(ftok, "insert|emplace"))
return ftok;
}
}
return nullptr;
}
namespace {
struct InvalidContainerAnalyzer {
struct Info {
struct Reference {
const Token* tok;
ErrorPath errorPath;
const Token* ftok;
};
std::unordered_map<int, Reference> expressions;
void add(const std::vector<Reference>& refs) {
for (const Reference& r : refs) {
add(r);
}
}
void add(const Reference& r) {
if (!r.tok)
return;
expressions.insert(std::make_pair(r.tok->exprId(), r));
}
std::vector<Reference> invalidTokens() const {
std::vector<Reference> result;
std::transform(expressions.cbegin(), expressions.cend(), std::back_inserter(result), SelectMapValues{});
return result;
}
};
std::unordered_map<const Function*, Info> invalidMethods;
std::vector<Info::Reference> invalidatesContainer(const Token* tok) const {
std::vector<Info::Reference> result;
if (Token::Match(tok, "%name% (")) {
const Function* f = tok->function();
if (!f)
return result;
ErrorPathItem epi = std::make_pair(tok, "Calling function " + tok->str());
const bool dependsOnThis = exprDependsOnThis(tok->next());
auto it = invalidMethods.find(f);
if (it != invalidMethods.end()) {
std::vector<Info::Reference> refs = it->second.invalidTokens();
std::copy_if(refs.cbegin(), refs.cend(), std::back_inserter(result), [&](const Info::Reference& r) {
const Variable* var = r.tok->variable();
if (!var)
return false;
if (dependsOnThis && !var->isLocal() && !var->isGlobal() && !var->isStatic())
return true;
if (!var->isArgument())
return false;
if (!var->isReference())
return false;
return true;
});
std::vector<const Token*> args = getArguments(tok);
for (Info::Reference& r : result) {
r.errorPath.push_front(epi);
r.ftok = tok;
const Variable* var = r.tok->variable();
if (!var)
continue;
if (var->isArgument()) {
const int n = getArgumentPos(var, f);
const Token* tok2 = nullptr;
if (n >= 0 && n < args.size())
tok2 = args[n];
r.tok = tok2;
}
}
}
} else if (astIsContainer(tok)) {
const Token* ftok = getInvalidMethod(tok);
if (ftok) {
ErrorPath ep;
ep.emplace_front(ftok,
"After calling '" + ftok->expressionString() +
"', iterators or references to the container's data may be invalid .");
result.emplace_back(Info::Reference{tok, ep, ftok});
}
}
return result;
}
void analyze(const SymbolDatabase* symboldatabase) {
for (const Scope* scope : symboldatabase->functionScopes) {
const Function* f = scope->function;
if (!f)
continue;
for (const Token* tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) {
if (Token::Match(tok, "if|while|for|goto|return"))
break;
std::vector<Info::Reference> c = invalidatesContainer(tok);
if (c.empty())
continue;
invalidMethods[f].add(c);
}
}
}
};
}
static const Token* getLoopContainer(const Token* tok)
{
if (!Token::simpleMatch(tok, "for ("))
return nullptr;
const Token* sepTok = tok->next()->astOperand2();
if (!Token::simpleMatch(sepTok, ":"))
return nullptr;
return sepTok->astOperand2();
}
static const ValueFlow::Value* getInnerLifetime(const Token* tok,
nonneg int id,
ErrorPath* errorPath = nullptr,
int depth = 4)
{
if (depth < 0)
return nullptr;
if (!tok)
return nullptr;
for (const ValueFlow::Value& val : tok->values()) {
if (!val.isLocalLifetimeValue())
continue;
if (contains({ValueFlow::Value::LifetimeKind::Address,
ValueFlow::Value::LifetimeKind::SubObject,
ValueFlow::Value::LifetimeKind::Lambda},
val.lifetimeKind)) {
if (val.isInconclusive())
return nullptr;
if (val.capturetok)
return getInnerLifetime(val.capturetok, id, errorPath, depth - 1);
if (errorPath)
errorPath->insert(errorPath->end(), val.errorPath.cbegin(), val.errorPath.cend());
return getInnerLifetime(val.tokvalue, id, errorPath, depth - 1);
}
if (!val.tokvalue->variable())
continue;
if (val.tokvalue->varId() != id)
continue;
return &val;
}
return nullptr;
}
static const Token* endOfExpression(const Token* tok)
{
if (!tok)
return nullptr;
const Token* parent = tok->astParent();
while (Token::simpleMatch(parent, "."))
parent = parent->astParent();
if (!parent)
return tok->next();
const Token* endToken = nextAfterAstRightmostLeaf(parent);
if (!endToken)
return parent->next();
return endToken;
}
void CheckStl::invalidContainer()
{
logChecker("CheckStl::invalidContainer");
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
const Library& library = mSettings->library;
InvalidContainerAnalyzer analyzer;
analyzer.analyze(symbolDatabase);
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (const Token* contTok = getLoopContainer(tok)) {
const Token* blockStart = tok->next()->link()->next();
const Token* blockEnd = blockStart->link();
if (contTok->exprId() == 0)
continue;
if (!astIsContainer(contTok))
continue;
for (const Token* tok2 = blockStart; tok2 != blockEnd; tok2 = tok2->next()) {
bool bail = false;
for (const InvalidContainerAnalyzer::Info::Reference& r : analyzer.invalidatesContainer(tok2)) {
if (!astIsContainer(r.tok))
continue;
if (r.tok->exprId() != contTok->exprId())
continue;
const Scope* s = tok2->scope();
if (!s)
continue;
if (isReturnScope(s->bodyEnd, &mSettings->library))
continue;
invalidContainerLoopError(r.ftok, tok, r.errorPath);
bail = true;
break;
}
if (bail)
break;
}
} else {
for (const InvalidContainerAnalyzer::Info::Reference& r : analyzer.invalidatesContainer(tok)) {
if (!astIsContainer(r.tok))
continue;
std::set<nonneg int> skipVarIds;
// Skip if the variable is assigned to
const Token* assignExpr = tok;
while (assignExpr->astParent()) {
const bool isRHS = astIsRHS(assignExpr);
assignExpr = assignExpr->astParent();
if (Token::Match(assignExpr, "%assign%")) {
if (!isRHS)
assignExpr = nullptr;
break;
}
}
if (Token::Match(assignExpr, "%assign%") && Token::Match(assignExpr->astOperand1(), "%var%"))
skipVarIds.insert(assignExpr->astOperand1()->varId());
const Token* endToken = endOfExpression(tok);
const ValueFlow::Value* v = nullptr;
ErrorPath errorPath;
PathAnalysis::Info info =
PathAnalysis{endToken, library}.forwardFind([&](const PathAnalysis::Info& info) {
if (!info.tok->variable())
return false;
if (info.tok->varId() == 0)
return false;
if (skipVarIds.count(info.tok->varId()) > 0)
return false;
// if (Token::simpleMatch(info.tok->next(), "."))
// return false;
if (Token::Match(info.tok->astParent(), "%assign%") && astIsLHS(info.tok))
skipVarIds.insert(info.tok->varId());
if (info.tok->variable()->isReference() && !isVariableDecl(info.tok) &&
reaches(info.tok->variable()->nameToken(), tok, library, nullptr)) {
ErrorPath ep;
bool addressOf = false;
const Variable* var = ValueFlow::getLifetimeVariable(info.tok, ep, &addressOf);
// Check the reference is created before the change
if (var && var->declarationId() == r.tok->varId() && !addressOf) {
// An argument always reaches
if (var->isArgument() ||
(!var->isReference() && !var->isRValueReference() && !isVariableDecl(tok) &&
reaches(var->nameToken(), tok, library, &ep))) {
errorPath = ep;
return true;
}
}
}
ErrorPath ep;
const ValueFlow::Value* val = getInnerLifetime(info.tok, r.tok->varId(), &ep);
// Check the iterator is created before the change
if (val && val->tokvalue != tok && reaches(val->tokvalue, tok, library, &ep)) {
v = val;
errorPath = ep;
return true;
}
return false;
});
if (!info.tok)
continue;
errorPath.insert(errorPath.end(), info.errorPath.cbegin(), info.errorPath.cend());
errorPath.insert(errorPath.end(), r.errorPath.cbegin(), r.errorPath.cend());
if (v) {
invalidContainerError(info.tok, r.tok, v, errorPath);
} else {
invalidContainerReferenceError(info.tok, r.tok, errorPath);
}
}
}
}
}
}
void CheckStl::invalidContainerLoopError(const Token* tok, const Token* loopTok, ErrorPath errorPath)
{
const std::string method = tok ? tok->str() : "erase";
errorPath.emplace_back(loopTok, "Iterating container here.");
// Remove duplicate entries from error path
errorPath.remove_if([&](const ErrorPathItem& epi) {
return epi.first == tok;
});
const std::string msg = "Calling '" + method + "' while iterating the container is invalid.";
errorPath.emplace_back(tok, "");
reportError(errorPath, Severity::error, "invalidContainerLoop", msg, CWE664, Certainty::normal);
}
void CheckStl::invalidContainerError(const Token *tok, const Token * /*contTok*/, const ValueFlow::Value *val, ErrorPath errorPath)
{
const bool inconclusive = val ? val->isInconclusive() : false;
if (val)
errorPath.insert(errorPath.begin(), val->errorPath.cbegin(), val->errorPath.cend());
std::string msg = "Using " + lifetimeMessage(tok, val, errorPath);
errorPath.emplace_back(tok, "");
reportError(errorPath, Severity::error, "invalidContainer", msg + " that may be invalid.", CWE664, inconclusive ? Certainty::inconclusive : Certainty::normal);
}
void CheckStl::invalidContainerReferenceError(const Token* tok, const Token* contTok, ErrorPath errorPath)
{
std::string name = contTok ? contTok->expressionString() : "x";
std::string msg = "Reference to " + name;
errorPath.emplace_back(tok, "");
reportError(errorPath, Severity::error, "invalidContainerReference", msg + " that may be invalid.", CWE664, Certainty::normal);
}
void CheckStl::stlOutOfBounds()
{
logChecker("CheckStl::stlOutOfBounds");
const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase();
// Scan through all scopes..
for (const Scope &scope : symbolDatabase->scopeList) {
const Token* tok = scope.classDef;
// only interested in conditions
if ((!scope.isLoopScope() && scope.type != Scope::eIf) || !tok)
continue;
const Token *condition = nullptr;
if (scope.type == Scope::eFor) {
if (Token::simpleMatch(tok->next()->astOperand2(), ";") && Token::simpleMatch(tok->next()->astOperand2()->astOperand2(), ";"))
condition = tok->next()->astOperand2()->astOperand2()->astOperand1();
} else if (Token::simpleMatch(tok, "do {") && Token::simpleMatch(tok->linkAt(1), "} while ("))
condition = tok->linkAt(1)->tokAt(2)->astOperand2();
else
condition = tok->next()->astOperand2();
if (!condition)
continue;
std::vector<const Token *> conds;
visitAstNodes(condition,
[&](const Token *cond) {
if (Token::Match(cond, "%oror%|&&"))
return ChildrenToVisit::op1_and_op2;
if (cond->isComparisonOp())
conds.emplace_back(cond);
return ChildrenToVisit::none;
});
for (const Token *cond : conds) {
const Token *vartok;
const Token *containerToken;
// check in the ast that cond is of the form "%var% <= %var% . %name% ( )"
if (cond->str() == "<=" && Token::Match(cond->astOperand1(), "%var%") &&
cond->astOperand2()->str() == "(" && cond->astOperand2()->astOperand1()->str() == "." &&
Token::Match(cond->astOperand2()->astOperand1()->astOperand1(), "%var%") &&
Token::Match(cond->astOperand2()->astOperand1()->astOperand2(), "%name%")) {
vartok = cond->astOperand1();
containerToken = cond->next();
} else {
continue;
}
if (containerToken->hasKnownValue(ValueFlow::Value::ValueType::CONTAINER_SIZE))
continue;
// Is it a array like container?
const Library::Container* container = containerToken->valueType() ? containerToken->valueType()->container : nullptr;
if (!container)
continue;
if (container->getYield(containerToken->strAt(2)) != Library::Container::Yield::SIZE)
continue;
// variable id for loop variable.
const int numId = vartok->varId();
// variable id for the container variable
const int declarationId = containerToken->varId();
const std::string &containerName = containerToken->str();
for (const Token *tok3 = scope.bodyStart; tok3 && tok3 != scope.bodyEnd; tok3 = tok3->next()) {
if (tok3->varId() == declarationId) {
tok3 = tok3->next();
if (Token::Match(tok3, ". %name% ( )")) {
if (container->getYield(tok3->strAt(1)) == Library::Container::Yield::SIZE)
break;
} else if (container->arrayLike_indexOp && Token::Match(tok3, "[ %varid% ]", numId))
stlOutOfBoundsError(tok3, tok3->strAt(1), containerName, false);
else if (Token::Match(tok3, ". %name% ( %varid% )", numId)) {
const Library::Container::Yield yield = container->getYield(tok3->strAt(1));
if (yield == Library::Container::Yield::AT_INDEX)
stlOutOfBoundsError(tok3, tok3->strAt(3), containerName, true);
}
}
}
}
}
}
void CheckStl::stlOutOfBoundsError(const Token *tok, const std::string &num, const std::string &var, bool at)
{
if (at)
reportError(tok, Severity::error, "stlOutOfBounds", "$symbol:" + var + "\nWhen " + num + "==$symbol.size(), $symbol.at(" + num + ") is out of bounds.", CWE788, Certainty::normal);
else
reportError(tok, Severity::error, "stlOutOfBounds", "$symbol:" + var + "\nWhen " + num + "==$symbol.size(), $symbol[" + num + "] is out of bounds.", CWE788, Certainty::normal);
}
void CheckStl::negativeIndex()
{
logChecker("CheckStl::negativeIndex");
// Negative index is out of bounds..
const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (!Token::Match(tok, "%var% [") || !tok->next()->astOperand2())
continue;
const Variable * const var = tok->variable();
if (!var || tok == var->nameToken())
continue;
const Library::Container * const container = mSettings->library.detectContainer(var->typeStartToken());
if (!container || !container->arrayLike_indexOp)
continue;
const ValueFlow::Value *index = tok->next()->astOperand2()->getValueLE(-1, mSettings);
if (!index)
continue;
negativeIndexError(tok, *index);
}
}
}
void CheckStl::negativeIndexError(const Token *tok, const ValueFlow::Value &index)
{
const ErrorPath errorPath = getErrorPath(tok, &index, "Negative array index");
std::ostringstream errmsg;
if (index.condition)
errmsg << ValueFlow::eitherTheConditionIsRedundant(index.condition)
<< ", otherwise there is negative array index " << index.intvalue << ".";
else
errmsg << "Array index " << index.intvalue << " is out of bounds.";
const auto severity = index.errorSeverity() && index.isKnown() ? Severity::error : Severity::warning;
const auto certainty = index.isInconclusive() ? Certainty::inconclusive : Certainty::normal;
reportError(errorPath, severity, "negativeContainerIndex", errmsg.str(), CWE786, certainty);
}
void CheckStl::erase()
{
logChecker("CheckStl::erase");
const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope &scope : symbolDatabase->scopeList) {
if (scope.type == Scope::eFor && Token::simpleMatch(scope.classDef, "for (")) {
const Token *tok = scope.classDef->linkAt(1);
if (!Token::Match(tok->tokAt(-3), "; ++| %var% ++| ) {"))
continue;
tok = tok->previous();
if (!tok->isName())
tok = tok->previous();
eraseCheckLoopVar(scope, tok->variable());
} else if (scope.type == Scope::eWhile && Token::Match(scope.classDef, "while ( %var% !=")) {
eraseCheckLoopVar(scope, scope.classDef->tokAt(2)->variable());
}
}
}
void CheckStl::eraseCheckLoopVar(const Scope &scope, const Variable *var)
{
bool inconclusiveType=false;
if (!isIterator(var, inconclusiveType))
return;
for (const Token *tok = scope.bodyStart; tok != scope.bodyEnd; tok = tok->next()) {
if (tok->str() != "(")
continue;
if (!Token::Match(tok->tokAt(-2), ". erase ( ++| %varid% )", var->declarationId()))
continue;
// Vector erases are handled by invalidContainer check
if (isVector(tok->tokAt(-3)))
continue;
if (Token::Match(tok->astParent(), "=|return"))
continue;
// Iterator is invalid..
int indentlevel = 0U;
const Token *tok2 = tok->link();
for (; tok2 != scope.bodyEnd; tok2 = tok2->next()) {
if (tok2->str() == "{") {
++indentlevel;
continue;
}
if (tok2->str() == "}") {
if (indentlevel > 0U)
--indentlevel;
else if (Token::simpleMatch(tok2, "} else {"))
tok2 = tok2->linkAt(2);
continue;
}
if (tok2->varId() == var->declarationId()) {
if (Token::simpleMatch(tok2->next(), "="))
break;
dereferenceErasedError(tok, tok2, tok2->str(), inconclusiveType);
break;
}
if (indentlevel == 0U && Token::Match(tok2, "break|return|goto"))
break;
}
if (tok2 == scope.bodyEnd)
dereferenceErasedError(tok, scope.classDef, var->nameToken()->str(), inconclusiveType);
}
}
void CheckStl::stlBoundaries()
{
logChecker("CheckStl::stlBoundaries");
const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Variable* var : symbolDatabase->variableList()) {
if (!var || !var->scope() || !var->scope()->isExecutable())
continue;
const Library::Container* container = mSettings->library.detectIterator(var->typeStartToken());
if (!container || container->opLessAllowed)
continue;
const Token* const end = var->scope()->bodyEnd;
for (const Token *tok = var->nameToken(); tok != end; tok = tok->next()) {
if (Token::Match(tok, "!!* %varid% <", var->declarationId())) {
stlBoundariesError(tok);
} else if (Token::Match(tok, "> %varid% !!.", var->declarationId())) {
stlBoundariesError(tok);
}
}
}
}
// Error message for bad boundary usage..
void CheckStl::stlBoundariesError(const Token *tok)
{
reportError(tok, Severity::error, "stlBoundaries",
"Dangerous comparison using operator< on iterator.\n"
"Iterator compared with operator<. This is dangerous since the order of items in the "
"container is not guaranteed. One should use operator!= instead to compare iterators.", CWE664, Certainty::normal);
}
static bool if_findCompare(const Token * const tokBack, bool stdStringLike)
{
const Token *tok = tokBack->astParent();
if (!tok)
return true;
if (tok->isComparisonOp()) {
if (stdStringLike) {
const Token * const tokOther = tokBack->astSibling();
return !tokOther || !tokOther->hasKnownIntValue() || tokOther->getKnownIntValue() != 0;
}
return (!tok->astOperand1()->isNumber() && !tok->astOperand2()->isNumber());
}
if (tok->isArithmeticalOp()) // result is used in some calculation
return true; // TODO: check if there is a comparison of the result somewhere
if (tok->str() == ".")
return true; // Dereferencing is OK, the programmer might know that the element exists - TODO: An inconclusive warning might be appropriate
if (tok->isAssignmentOp())
return if_findCompare(tok, stdStringLike); // Go one step upwards in the AST
return false;
}
void CheckStl::if_find()
{
const bool printWarning = mSettings->severity.isEnabled(Severity::warning);
const bool printPerformance = mSettings->severity.isEnabled(Severity::performance);
if (!printWarning && !printPerformance)
return;
logChecker("CheckStl::if_find"); // warning,performance
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope &scope : symbolDatabase->scopeList) {
if ((scope.type != Scope::eIf && scope.type != Scope::eWhile) || !scope.classDef)
continue;
const Token *conditionStart = scope.classDef->next();
if (Token::simpleMatch(conditionStart->astOperand2(), ";"))
conditionStart = conditionStart->astOperand2();
for (const Token *tok = conditionStart; tok->str() != "{"; tok = tok->next()) {
const Token* funcTok = nullptr;
const Library::Container* container = nullptr;
if (Token::Match(tok, "%name% ("))
tok = tok->linkAt(1);
else if (tok->variable() && Token::Match(tok, "%var% . %name% (")) {
container = mSettings->library.detectContainer(tok->variable()->typeStartToken());
funcTok = tok->tokAt(2);
}
// check also for vector-like or pointer containers
else if (tok->variable() && tok->astParent() && (tok->astParent()->str() == "*" || tok->astParent()->str() == "[")) {
const Token *tok2 = tok->astParent();
if (!Token::Match(tok2->astParent(), ". %name% ("))
continue;
funcTok = tok2->astParent()->next();
if (tok->variable()->isArrayOrPointer())
container = mSettings->library.detectContainer(tok->variable()->typeStartToken());
else { // Container of container - find the inner container
container = mSettings->library.detectContainer(tok->variable()->typeStartToken()); // outer container
tok2 = Token::findsimplematch(tok->variable()->typeStartToken(), "<", tok->variable()->typeEndToken());
if (container && container->type_templateArgNo >= 0 && tok2) {
tok2 = tok2->next();
for (int j = 0; j < container->type_templateArgNo; j++)
tok2 = tok2->nextTemplateArgument();
container = mSettings->library.detectContainer(tok2); // inner container
} else
container = nullptr;
}
}
Library::Container::Action action{};
if (container &&
((action = container->getAction(funcTok->str())) == Library::Container::Action::FIND || action == Library::Container::Action::FIND_CONST)) {
if (if_findCompare(funcTok->next(), container->stdStringLike))
continue;
if (printWarning && container->getYield(funcTok->str()) == Library::Container::Yield::ITERATOR)
if_findError(tok, false);
else if (printPerformance && container->stdStringLike && funcTok->str() == "find")
if_findError(tok, true);
} else if (printWarning && Token::Match(tok, "std :: find|find_if (")) {
// check that result is checked properly
if (!if_findCompare(tok->tokAt(3), false)) {
if_findError(tok, false);
}
}
}
}
}
void CheckStl::if_findError(const Token *tok, bool str)
{
if (str && mSettings->standards.cpp >= Standards::CPP20)
reportError(tok, Severity::performance, "stlIfStrFind",
"Inefficient usage of string::find() in condition; string::starts_with() could be faster.\n"
"Either inefficient or wrong usage of string::find(). string::starts_with() will be faster if "
"string::find's result is compared with 0, because it will not scan the whole "
"string. If your intention is to check that there are no findings in the string, "
"you should compare with std::string::npos.", CWE597, Certainty::normal);
if (!str)
reportError(tok, Severity::warning, "stlIfFind", "Suspicious condition. The result of find() is an iterator, but it is not properly checked.", CWE398, Certainty::normal);
}
static std::pair<const Token *, const Token *> isMapFind(const Token *tok)
{
if (!Token::simpleMatch(tok, "("))
return {};
if (!Token::simpleMatch(tok->astOperand1(), "."))
return {};
if (!astIsContainer(tok->astOperand1()->astOperand1()))
return {};
const Token * contTok = tok->astOperand1()->astOperand1();
const Library::Container * container = contTok->valueType()->container;
if (!container)
return {};
if (!container->stdAssociativeLike)
return {};
if (!Token::Match(tok->astOperand1(), ". find|count ("))
return {};
if (!tok->astOperand2())
return {};
return {contTok, tok->astOperand2()};
}
static const Token* skipLocalVars(const Token* const tok)
{
if (!tok)
return tok;
if (Token::simpleMatch(tok, "{"))
return skipLocalVars(tok->next());
const Token *top = tok->astTop();
if (!top) {
const Token *semi = Token::findsimplematch(tok, ";");
if (!semi)
return tok;
if (!Token::Match(semi->previous(), "%var% ;"))
return tok;
const Token *varTok = semi->previous();
const Variable *var = varTok->variable();
if (!var)
return tok;
if (var->nameToken() != varTok)
return tok;
return skipLocalVars(semi->next());
}
if (tok->isAssignmentOp()) {
const Token *varTok = top->astOperand1();
const Variable *var = varTok->variable();
if (!var)
return tok;
if (var->scope() != tok->scope())
return tok;
const Token *endTok = nextAfterAstRightmostLeaf(top);
if (!endTok)
return tok;
return skipLocalVars(endTok->next());
}
return tok;
}
static const Token *findInsertValue(const Token *tok, const Token *containerTok, const Token *keyTok, const Library &library)
{
const Token *startTok = skipLocalVars(tok);
const Token *top = startTok->astTop();
const Token *icontainerTok = nullptr;
const Token *ikeyTok = nullptr;
const Token *ivalueTok = nullptr;
if (Token::simpleMatch(top, "=") && Token::simpleMatch(top->astOperand1(), "[")) {
icontainerTok = top->astOperand1()->astOperand1();
ikeyTok = top->astOperand1()->astOperand2();
ivalueTok = top->astOperand2();
}
if (Token::simpleMatch(top, "(") && Token::Match(top->astOperand1(), ". insert|emplace (") && !astIsIterator(top->astOperand1()->tokAt(2))) {
icontainerTok = top->astOperand1()->astOperand1();
const Token *itok = top->astOperand1()->tokAt(2)->astOperand2();
if (Token::simpleMatch(itok, ",")) {
ikeyTok = itok->astOperand1();
ivalueTok = itok->astOperand2();
} else {
ikeyTok = itok;
}
}
if (!ikeyTok || !icontainerTok)
return nullptr;
if (isSameExpression(true, true, containerTok, icontainerTok, library, true, false) &&
isSameExpression(true, true, keyTok, ikeyTok, library, true, true)) {
if (ivalueTok)
return ivalueTok;
return ikeyTok;
}
return nullptr;
}
void CheckStl::checkFindInsert()
{
if (!mSettings->severity.isEnabled(Severity::performance))
return;
logChecker("CheckStl::checkFindInsert"); // performance
const SymbolDatabase *const symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope *scope : symbolDatabase->functionScopes) {
for (const Token *tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (!Token::simpleMatch(tok, "if ("))
continue;
if (!Token::simpleMatch(tok->next()->link(), ") {"))
continue;
if (!Token::Match(tok->next()->astOperand2(), "%comp%"))
continue;
const Token *condTok = tok->next()->astOperand2();
const Token *containerTok;
const Token *keyTok;
std::tie(containerTok, keyTok) = isMapFind(condTok->astOperand1());
if (!containerTok)
continue;
// In < C++17 we only warn for small simple types
if (mSettings->standards.cpp < Standards::CPP17 && !(keyTok && keyTok->valueType() && (keyTok->valueType()->isIntegral() || keyTok->valueType()->pointer > 0)))
continue;
const Token *thenTok = tok->next()->link()->next();
const Token *valueTok = findInsertValue(thenTok, containerTok, keyTok, mSettings->library);
if (!valueTok)
continue;
if (Token::simpleMatch(thenTok->link(), "} else {")) {
const Token *valueTok2 =
findInsertValue(thenTok->link()->tokAt(2), containerTok, keyTok, mSettings->library);
if (!valueTok2)
continue;
if (isSameExpression(true, true, valueTok, valueTok2, mSettings->library, true, true)) {
checkFindInsertError(valueTok);
}
} else {
checkFindInsertError(valueTok);
}
}
}
}
void CheckStl::checkFindInsertError(const Token *tok)
{
std::string replaceExpr;
if (tok && Token::simpleMatch(tok->astParent(), "=") && tok == tok->astParent()->astOperand2() && Token::simpleMatch(tok->astParent()->astOperand1(), "[")) {
if (mSettings->standards.cpp < Standards::CPP11)
// We will recommend using emplace/try_emplace instead
return;
const std::string f = (mSettings->standards.cpp < Standards::CPP17) ? "emplace" : "try_emplace";
replaceExpr = " Instead of '" + tok->astParent()->expressionString() + "' consider using '" +
tok->astParent()->astOperand1()->astOperand1()->expressionString() +
"." + f + "(" +
tok->astParent()->astOperand1()->astOperand2()->expressionString() +
", " +
tok->expressionString() +
");'.";
}
reportError(
tok, Severity::performance, "stlFindInsert", "Searching before insertion is not necessary." + replaceExpr, CWE398, Certainty::normal);
}
/**
* Is container.size() slow?
*/
static bool isCpp03ContainerSizeSlow(const Token *tok)
{
if (!tok)
return false;
const Variable* var = tok->variable();
return var && var->isStlType("list");
}
void CheckStl::size()
{
if (!mSettings->severity.isEnabled(Severity::performance))
return;
if (mSettings->standards.cpp >= Standards::CPP11)
return;
logChecker("CheckStl::size"); // performance,c++03
const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (Token::Match(tok, "%var% . size ( )") ||
Token::Match(tok, "%name% . %var% . size ( )")) {
// get the variable
const Token *varTok = tok;
if (tok->strAt(2) != "size")
varTok = varTok->tokAt(2);
const Token* const end = varTok->tokAt(5);
// check for comparison to zero
if ((!tok->previous()->isArithmeticalOp() && Token::Match(end, "==|<=|!=|> 0")) ||
(end->next() && !end->next()->isArithmeticalOp() && Token::Match(tok->tokAt(-2), "0 ==|>=|!=|<"))) {
if (isCpp03ContainerSizeSlow(varTok)) {
sizeError(varTok);
continue;
}
}
// check for comparison to one
if ((!tok->previous()->isArithmeticalOp() && Token::Match(end, ">=|< 1") && !end->tokAt(2)->isArithmeticalOp()) ||
(end->next() && !end->next()->isArithmeticalOp() && Token::Match(tok->tokAt(-2), "1 <=|>") && !tok->tokAt(-3)->isArithmeticalOp())) {
if (isCpp03ContainerSizeSlow(varTok))
sizeError(varTok);
}
// check for using as boolean expression
else if ((Token::Match(tok->tokAt(-2), "if|while (") && end->str() == ")") ||
(tok->previous()->tokType() == Token::eLogicalOp && Token::Match(end, "&&|)|,|;|%oror%"))) {
if (isCpp03ContainerSizeSlow(varTok))
sizeError(varTok);
}
}
}
}
}
void CheckStl::sizeError(const Token *tok)
{
const std::string varname = tok ? tok->str() : std::string("list");
reportError(tok, Severity::performance, "stlSize",
"$symbol:" + varname + "\n"
"Possible inefficient checking for '$symbol' emptiness.\n"
"Checking for '$symbol' emptiness might be inefficient. "
"Using $symbol.empty() instead of $symbol.size() can be faster. "
"$symbol.size() can take linear time but $symbol.empty() is "
"guaranteed to take constant time.", CWE398, Certainty::normal);
}
void CheckStl::redundantCondition()
{
if (!mSettings->severity.isEnabled(Severity::style))
return;
logChecker("CheckStl::redundantCondition"); // style
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope &scope : symbolDatabase->scopeList) {
if (scope.type != Scope::eIf)
continue;
const Token* tok = scope.classDef->tokAt(2);
if (!Token::Match(tok, "%name% . find ( %any% ) != %name% . end|rend|cend|crend ( ) ) { %name% . remove|erase ( %any% ) ;"))
continue;
// Get tokens for the fields %name% and %any%
const Token *var1 = tok;
const Token *any1 = var1->tokAt(4);
const Token *var2 = any1->tokAt(3);
const Token *var3 = var2->tokAt(7);
const Token *any2 = var3->tokAt(4);
// Check if all the "%name%" fields are the same and if all the "%any%" are the same..
if (var1->str() == var2->str() &&
var2->str() == var3->str() &&
any1->str() == any2->str()) {
redundantIfRemoveError(tok);
}
}
}
void CheckStl::redundantIfRemoveError(const Token *tok)
{
reportError(tok, Severity::style, "redundantIfRemove",
"Redundant checking of STL container element existence before removing it.\n"
"Redundant checking of STL container element existence before removing it. "
"It is safe to call the remove method on a non-existing element.", CWE398, Certainty::normal);
}
void CheckStl::missingComparison()
{
if (!mSettings->severity.isEnabled(Severity::warning))
return;
logChecker("CheckStl::missingComparison"); // warning
const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope &scope : symbolDatabase->scopeList) {
if (scope.type != Scope::eFor || !scope.classDef)
continue;
for (const Token *tok2 = scope.classDef->tokAt(2); tok2 != scope.bodyStart; tok2 = tok2->next()) {
if (tok2->str() == ";")
break;
if (!Token::Match(tok2, "%var% = %name% . begin|rbegin|cbegin|crbegin ( ) ; %name% != %name% . end|rend|cend|crend ( ) ; ++| %name% ++| ) {"))
continue;
// same container
if (tok2->strAt(2) != tok2->strAt(10))
break;
const int iteratorId(tok2->varId());
// same iterator
if (iteratorId == tok2->tokAt(10)->varId())
break;
// increment iterator
if (!Token::Match(tok2->tokAt(16), "++ %varid% )", iteratorId) &&
!Token::Match(tok2->tokAt(16), "%varid% ++ )", iteratorId)) {
break;
}
const Token *incrementToken = nullptr;
// Parse loop..
for (const Token *tok3 = scope.bodyStart; tok3 != scope.bodyEnd; tok3 = tok3->next()) {
if (tok3->varId() == iteratorId) {
if (Token::Match(tok3, "%varid% = %name% . insert ( ++| %varid% ++| ,", iteratorId)) {
// skip insertion..
tok3 = tok3->linkAt(6);
if (!tok3)
break;
} else if (Token::simpleMatch(tok3->astParent(), "++"))
incrementToken = tok3;
else if (Token::simpleMatch(tok3->astParent(), "+")) {
if (Token::Match(tok3->astSibling(), "%num%")) {
const Token* tokenGrandParent = tok3->astParent()->astParent();
if (Token::Match(tokenGrandParent, "==|!="))
break;
}
} else if (Token::Match(tok3->astParent(), "==|!="))
incrementToken = nullptr;
} else if (tok3->str() == "break" || tok3->str() == "return")
incrementToken = nullptr;
}
if (incrementToken)
missingComparisonError(incrementToken, tok2->tokAt(16));
}
}
}
void CheckStl::missingComparisonError(const Token *incrementToken1, const Token *incrementToken2)
{
std::list<const Token*> callstack = { incrementToken1,incrementToken2 };
std::ostringstream errmsg;
errmsg << "Missing bounds check for extra iterator increment in loop.\n"
<< "The iterator incrementing is suspicious - it is incremented at line ";
if (incrementToken1)
errmsg << incrementToken1->linenr();
errmsg << " and then at line ";
if (incrementToken2)
errmsg << incrementToken2->linenr();
errmsg << ". The loop might unintentionally skip an element in the container. "
<< "There is no comparison between these increments to prevent that the iterator is "
<< "incremented beyond the end.";
reportError(callstack, Severity::warning, "StlMissingComparison", errmsg.str(), CWE834, Certainty::normal);
}
static bool isLocal(const Token *tok)
{
const Variable *var = tok->variable();
return var && !var->isStatic() && var->isLocal();
}
namespace {
const std::set<std::string> stl_string_stream = {
"istringstream", "ostringstream", "stringstream", "wstringstream"
};
}
void CheckStl::string_c_str()
{
const bool printInconclusive = mSettings->certainty.isEnabled(Certainty::inconclusive);
const bool printPerformance = mSettings->severity.isEnabled(Severity::performance);
const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase();
logChecker("CheckStl::string_c_str");
// Find all functions that take std::string as argument
struct StrArg {
nonneg int n;
std::string argtype;
};
std::multimap<const Function*, StrArg> c_strFuncParam;
if (printPerformance) {
for (const Scope &scope : symbolDatabase->scopeList) {
for (const Function &func : scope.functionList) {
nonneg int numpar = 0;
for (const Variable &var : func.argumentList) {
numpar++;
if ((var.isStlStringType() || var.isStlStringViewType()) && (!var.isReference() || var.isConst()))
c_strFuncParam.emplace(&func, StrArg{ numpar, var.getTypeName() });
}
}
}
}
auto isString = [](const Token* str) -> bool {
while (Token::Match(str, "::|."))
str = str->astOperand2();
if (Token::Match(str, "(|[") && !(str->valueType() && str->valueType()->type == ValueType::ITERATOR))
str = str->previous();
return str && ((str->variable() && str->variable()->isStlStringType()) || // variable
(str->function() && isStlStringType(str->function()->retDef)) || // function returning string
(str->valueType() && str->valueType()->type == ValueType::ITERATOR && isStlStringType(str->valueType()->containerTypeToken))); // iterator pointing to string
};
// Try to detect common problems when using string::c_str()
for (const Scope &scope : symbolDatabase->scopeList) {
if (scope.type != Scope::eFunction || !scope.function)
continue;
enum {charPtr, stdString, stdStringConstRef, Other} returnType = Other;
if (Token::Match(scope.function->tokenDef->tokAt(-2), "char|wchar_t *"))
returnType = charPtr;
else if (Token::Match(scope.function->tokenDef->tokAt(-5), "const std :: string|wstring &"))
returnType = stdStringConstRef;
else if (Token::Match(scope.function->tokenDef->tokAt(-3), "std :: string|wstring !!&"))
returnType = stdString;
for (const Token *tok = scope.bodyStart; tok && tok != scope.bodyEnd; tok = tok->next()) {
// Invalid usage..
if (Token::Match(tok, "throw %var% . c_str|data ( ) ;") && isLocal(tok->next()) &&
tok->next()->variable() && tok->next()->variable()->isStlStringType()) {
string_c_strThrowError(tok);
} else if (tok->variable() && tok->strAt(1) == "=") {
if (Token::Match(tok->tokAt(2), "%var% . str ( ) . c_str|data ( ) ;")) {
const Variable* var = tok->variable();
const Variable* var2 = tok->tokAt(2)->variable();
if (var->isPointer() && var2 && var2->isStlType(stl_string_stream))
string_c_strError(tok);
} else if (Token::Match(tok->tokAt(2), "%name% (") &&
Token::Match(tok->linkAt(3), ") . c_str|data ( ) ;") &&
tok->tokAt(2)->function() && Token::Match(tok->tokAt(2)->function()->retDef, "std :: string|wstring %name%")) {
const Variable* var = tok->variable();
if (var->isPointer())
string_c_strError(tok);
} else if (printPerformance && tok->tokAt(1)->astOperand2() && Token::Match(tok->tokAt(1)->astOperand2()->tokAt(-3), "%var% . c_str|data ( ) ;")) {
const Token* vartok = tok->tokAt(1)->astOperand2()->tokAt(-3);
if ((tok->variable()->isStlStringType() || tok->variable()->isStlStringViewType()) && vartok->variable() && vartok->variable()->isStlStringType())
string_c_strAssignment(tok, tok->variable()->getTypeName());
}
} else if (printPerformance && tok->function() && Token::Match(tok, "%name% ( !!)") && tok->str() != scope.className) {
const auto range = c_strFuncParam.equal_range(tok->function());
for (std::multimap<const Function*, StrArg>::const_iterator i = range.first; i != range.second; ++i) {
if (i->second.n == 0)
continue;
const Token* tok2 = tok->tokAt(2);
int j;
for (j = 0; tok2 && j < i->second.n - 1; j++)
tok2 = tok2->nextArgument();
if (tok2)
tok2 = tok2->nextArgument();
else
break;
if (!tok2 && j == i->second.n - 1)
tok2 = tok->next()->link();
else if (tok2)
tok2 = tok2->previous();
else
break;
if (tok2 && Token::Match(tok2->tokAt(-4), ". c_str|data ( )")) {
if (isString(tok2->tokAt(-4)->astOperand1())) {
string_c_strParam(tok, i->second.n, i->second.argtype);
} else if (Token::Match(tok2->tokAt(-9), "%name% . str ( )")) { // Check ss.str().c_str() as parameter
const Variable* ssVar = tok2->tokAt(-9)->variable();
if (ssVar && ssVar->isStlType(stl_string_stream))
string_c_strParam(tok, i->second.n, i->second.argtype);
}
}
}
} else if (printPerformance && Token::Match(tok, "%var% (|{ %var% . c_str|data ( ) !!,") &&
tok->variable() && (tok->variable()->isStlStringType() || tok->variable()->isStlStringViewType()) &&
tok->tokAt(2)->variable() && tok->tokAt(2)->variable()->isStlStringType()) {
string_c_strConstructor(tok, tok->variable()->getTypeName());
} else if (printPerformance && tok->next() && tok->next()->variable() && tok->next()->variable()->isStlStringType() && tok->valueType() && tok->valueType()->type == ValueType::CONTAINER &&
((Token::Match(tok->previous(), "%var% + %var% . c_str|data ( )") && tok->previous()->variable() && tok->previous()->variable()->isStlStringType()) ||
(Token::Match(tok->tokAt(-5), "%var% . c_str|data ( ) + %var%") && tok->tokAt(-5)->variable() && tok->tokAt(-5)->variable()->isStlStringType()))) {
string_c_strConcat(tok);
} else if (printPerformance && Token::simpleMatch(tok, "<<") && tok->astOperand2() && Token::Match(tok->astOperand2()->astOperand1(), ". c_str|data ( )")) {
const Token* str = tok->astOperand2()->astOperand1()->astOperand1();
if (isString(str)) {
const Token* strm = tok;
while (Token::simpleMatch(strm, "<<"))
strm = strm->astOperand1();
if (strm && strm->variable() && strm->variable()->isStlType())
string_c_strStream(tok);
}
}
// Using c_str() to get the return value is only dangerous if the function returns a char*
else if ((returnType == charPtr || (printPerformance && (returnType == stdString || returnType == stdStringConstRef))) && tok->str() == "return") {
bool err = false;
const Token* tok2 = tok->next();
if (Token::Match(tok2, "std :: string|wstring (") &&
Token::Match(tok2->linkAt(3), ") . c_str|data ( ) ;")) {
err = true;
} else if (Token::simpleMatch(tok2, "(") &&
Token::Match(tok2->link(), ") . c_str|data ( ) ;")) {
// Check for "+ localvar" or "+ std::string(" inside the bracket
bool is_implicit_std_string = printInconclusive;
const Token *search_end = tok2->link();
for (const Token *search_tok = tok2->next(); search_tok != search_end; search_tok = search_tok->next()) {
if (Token::Match(search_tok, "+ %var%") && isLocal(search_tok->next()) &&
search_tok->next()->variable() && search_tok->next()->variable()->isStlStringType()) {
is_implicit_std_string = true;
break;
}
if (Token::Match(search_tok, "+ std :: string|wstring (")) {
is_implicit_std_string = true;
break;
}
}
if (is_implicit_std_string)
err = true;
}
bool local = false;
bool ptrOrRef = false;
const Variable* lastVar = nullptr;
const Function* lastFunc = nullptr;
bool funcStr = false;
if (Token::Match(tok2, "%var% .")) {
local = isLocal(tok2);
bool refToNonLocal = false;
if (tok2->variable() && tok2->variable()->isReference()) {
const Token *refTok = tok2->variable()->nameToken();
refToNonLocal = true; // safe assumption is default to avoid FPs
if (Token::Match(refTok, "%var% = %var% .|;|["))
refToNonLocal = !isLocal(refTok->tokAt(2));
}
ptrOrRef = refToNonLocal || (tok2->variable() && (tok2->variable()->isPointer() || tok2->variable()->isSmartPointer()));
}
while (tok2) {
if (Token::Match(tok2, "%var% .|::")) {
if (ptrOrRef)
local = false;
lastVar = tok2->variable();
tok2 = tok2->tokAt(2);
} else if (Token::Match(tok2, "%name% (") && Token::simpleMatch(tok2->linkAt(1), ") .")) {
lastFunc = tok2->function();
local = false;
funcStr = tok2->str() == "str";
tok2 = tok2->linkAt(1)->tokAt(2);
} else
break;
}
if (Token::Match(tok2, "c_str|data ( ) ;")) {
if ((local || returnType != charPtr) && lastVar && lastVar->isStlStringType())
err = true;
else if (funcStr && lastVar && lastVar->isStlType(stl_string_stream))
err = true;
else if (lastFunc && Token::Match(lastFunc->tokenDef->tokAt(-3), "std :: string|wstring"))
err = true;
}
if (err) {
if (returnType == charPtr)
string_c_strError(tok);
else
string_c_strReturn(tok);
}
}
}
}
}
void CheckStl::string_c_strThrowError(const Token* tok)
{
reportError(tok, Severity::error, "stlcstrthrow", "Dangerous usage of c_str(). The value returned by c_str() is invalid after throwing exception.\n"
"Dangerous usage of c_str(). The string is destroyed after the c_str() call so the thrown pointer is invalid.");
}
void CheckStl::string_c_strError(const Token* tok)
{
reportError(tok, Severity::error, "stlcstr", "Dangerous usage of c_str(). The value returned by c_str() is invalid after this call.\n"
"Dangerous usage of c_str(). The c_str() return value is only valid until its string is deleted.", CWE664, Certainty::normal);
}
void CheckStl::string_c_strReturn(const Token* tok)
{
reportError(tok, Severity::performance, "stlcstrReturn", "Returning the result of c_str() in a function that returns std::string is slow and redundant.\n"
"The conversion from const char* as returned by c_str() to std::string creates an unnecessary string copy. Solve that by directly returning the string.", CWE704, Certainty::normal);
}
void CheckStl::string_c_strParam(const Token* tok, nonneg int number, const std::string& argtype)
{
std::ostringstream oss;
oss << "Passing the result of c_str() to a function that takes " << argtype << " as argument no. " << number << " is slow and redundant.\n"
"The conversion from const char* as returned by c_str() to " << argtype << " creates an unnecessary string copy or length calculation. Solve that by directly passing the string.";
reportError(tok, Severity::performance, "stlcstrParam", oss.str(), CWE704, Certainty::normal);
}
void CheckStl::string_c_strConstructor(const Token* tok, const std::string& argtype)
{
std::string msg = "Constructing a " + argtype + " from the result of c_str() is slow and redundant.\n"
"Constructing a " + argtype + " from const char* requires a call to strlen(). Solve that by directly passing the string.";
reportError(tok, Severity::performance, "stlcstrConstructor", msg, CWE704, Certainty::normal);
}
void CheckStl::string_c_strAssignment(const Token* tok, const std::string& argtype)
{
std::string msg = "Assigning the result of c_str() to a " + argtype + " is slow and redundant.\n"
"Assigning a const char* to a " + argtype + " requires a call to strlen(). Solve that by directly assigning the string.";
reportError(tok, Severity::performance, "stlcstrAssignment", msg, CWE704, Certainty::normal);
}
void CheckStl::string_c_strConcat(const Token* tok)
{
std::string msg = "Concatenating the result of c_str() and a std::string is slow and redundant.\n"
"Concatenating a const char* with a std::string requires a call to strlen(). Solve that by directly concatenating the strings.";
reportError(tok, Severity::performance, "stlcstrConcat", msg, CWE704, Certainty::normal);
}
void CheckStl::string_c_strStream(const Token* tok)
{
std::string msg = "Passing the result of c_str() to a stream is slow and redundant.\n"
"Passing a const char* to a stream requires a call to strlen(). Solve that by directly passing the string.";
reportError(tok, Severity::performance, "stlcstrStream", msg, CWE704, Certainty::normal);
}
//---------------------------------------------------------------------------
//
//---------------------------------------------------------------------------
namespace {
const std::set<std::string> stl_containers_with_empty_and_clear = {
"deque", "forward_list", "list",
"map", "multimap", "multiset", "set", "string",
"unordered_map", "unordered_multimap", "unordered_multiset",
"unordered_set", "vector", "wstring"
};
}
void CheckStl::uselessCalls()
{
const bool printPerformance = mSettings->severity.isEnabled(Severity::performance);
const bool printWarning = mSettings->severity.isEnabled(Severity::warning);
if (!printPerformance && !printWarning)
return;
logChecker("CheckStl::uselessCalls"); // performance,warning
const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token* tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) {
if (printWarning && Token::Match(tok, "%var% . compare|find|rfind|find_first_not_of|find_first_of|find_last_not_of|find_last_of ( %name% [,)]") &&
tok->varId() == tok->tokAt(4)->varId()) {
const Variable* var = tok->variable();
if (!var || !var->isStlType())
continue;
uselessCallsReturnValueError(tok->tokAt(4), tok->str(), tok->strAt(2));
} else if (printPerformance && Token::Match(tok, "%var% . swap ( %name% )") &&
tok->varId() == tok->tokAt(4)->varId()) {
const Variable* var = tok->variable();
if (!var || !var->isStlType())
continue;
uselessCallsSwapError(tok, tok->str());
} else if (printPerformance && Token::Match(tok, "%var% . substr (") && tok->variable() && tok->variable()->isStlStringType()) {
const Token* funcTok = tok->tokAt(3);
const std::vector<const Token*> args = getArguments(funcTok);
if (Token::Match(tok->tokAt(-2), "%var% =") && tok->varId() == tok->tokAt(-2)->varId() &&
!args.empty() && args[0]->hasKnownIntValue() && args[0]->getKnownIntValue() == 0) {
uselessCallsSubstrError(tok, Token::simpleMatch(funcTok->astParent(), "=") ? SubstrErrorType::PREFIX : SubstrErrorType::PREFIX_CONCAT);
} else if (args.empty() || (args[0]->hasKnownIntValue() && args[0]->getKnownIntValue() == 0 &&
(args.size() == 1 || (args.size() == 2 && tok->linkAt(3)->strAt(-1) == "npos" && !tok->linkAt(3)->previous()->variable())))) {
uselessCallsSubstrError(tok, SubstrErrorType::COPY);
} else if (args.size() == 2 && args[1]->hasKnownIntValue() && args[1]->getKnownIntValue() == 0) {
uselessCallsSubstrError(tok, SubstrErrorType::EMPTY);
}
} else if (printWarning && Token::Match(tok, "[{};] %var% . empty ( ) ;") &&
!tok->tokAt(4)->astParent() &&
tok->next()->variable() && tok->next()->variable()->isStlType(stl_containers_with_empty_and_clear))
uselessCallsEmptyError(tok->next());
else if (Token::Match(tok, "[{};] std :: remove|remove_if|unique (") && tok->tokAt(5)->nextArgument())
uselessCallsRemoveError(tok->next(), tok->strAt(3));
else if (printPerformance && tok->valueType() && tok->valueType()->type == ValueType::CONTAINER) {
if (Token::Match(tok, "%var% = { %var% . begin ( ) ,") && tok->varId() == tok->tokAt(3)->varId())
uselessCallsConstructorError(tok);
else if (const Variable* var = tok->variable()) {
std::string pattern = "%var% = ";
for (const Token* t = var->typeStartToken(); t != var->typeEndToken()->next(); t = t->next()) {
pattern += t->str();
pattern += ' ';
}
pattern += "{|( %varid% . begin ( ) ,";
if (Token::Match(tok, pattern.c_str(), tok->varId()))
uselessCallsConstructorError(tok);
}
}
}
}
}
void CheckStl::uselessCallsReturnValueError(const Token *tok, const std::string &varname, const std::string &function)
{
std::ostringstream errmsg;
errmsg << "$symbol:" << varname << '\n';
errmsg << "$symbol:" << function << '\n';
errmsg << "It is inefficient to call '" << varname << "." << function << "(" << varname << ")' as it always returns 0.\n"
<< "'std::string::" << function << "()' returns zero when given itself as parameter "
<< "(" << varname << "." << function << "(" << varname << ")). As it is currently the "
<< "code is inefficient. It is possible either the string searched ('"
<< varname << "') or searched for ('" << varname << "') is wrong.";
reportError(tok, Severity::warning, "uselessCallsCompare", errmsg.str(), CWE628, Certainty::normal);
}
void CheckStl::uselessCallsSwapError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::performance, "uselessCallsSwap",
"$symbol:" + varname + "\n"
"It is inefficient to swap a object with itself by calling '$symbol.swap($symbol)'\n"
"The 'swap()' function has no logical effect when given itself as parameter "
"($symbol.swap($symbol)). As it is currently the "
"code is inefficient. Is the object or the parameter wrong here?", CWE628, Certainty::normal);
}
void CheckStl::uselessCallsSubstrError(const Token *tok, SubstrErrorType type)
{
std::string msg = "Ineffective call of function 'substr' because ";
switch (type) {
case SubstrErrorType::EMPTY:
msg += "it returns an empty string.";
break;
case SubstrErrorType::COPY:
msg += "it returns a copy of the object. Use operator= instead.";
break;
case SubstrErrorType::PREFIX:
msg += "a prefix of the string is assigned to itself. Use resize() or pop_back() instead.";
break;
case SubstrErrorType::PREFIX_CONCAT:
msg += "a prefix of the string is assigned to itself. Use replace() instead.";
break;
}
reportError(tok, Severity::performance, "uselessCallsSubstr", msg, CWE398, Certainty::normal);
}
void CheckStl::uselessCallsConstructorError(const Token *tok)
{
const std::string msg = "Inefficient constructor call: container '" + tok->str() + "' is assigned a partial copy of itself. Use erase() or resize() instead.";
reportError(tok, Severity::performance, "uselessCallsConstructor", msg, CWE398, Certainty::normal);
}
void CheckStl::uselessCallsEmptyError(const Token *tok)
{
reportError(tok, Severity::warning, "uselessCallsEmpty", "Ineffective call of function 'empty()'. Did you intend to call 'clear()' instead?", CWE398, Certainty::normal);
}
void CheckStl::uselessCallsRemoveError(const Token *tok, const std::string& function)
{
reportError(tok, Severity::warning, "uselessCallsRemove",
"$symbol:" + function + "\n"
"Return value of std::$symbol() ignored. Elements remain in container.\n"
"The return value of std::$symbol() is ignored. This function returns an iterator to the end of the range containing those elements that should be kept. "
"Elements past new end remain valid but with unspecified values. Use the erase method of the container to delete them.", CWE762, Certainty::normal);
}
// Check for iterators being dereferenced before being checked for validity.
// E.g. if (*i && i != str.end()) { }
void CheckStl::checkDereferenceInvalidIterator()
{
if (!mSettings->severity.isEnabled(Severity::warning))
return;
logChecker("CheckStl::checkDereferenceInvalidIterator"); // warning
// Iterate over "if", "while", and "for" conditions where there may
// be an iterator that is dereferenced before being checked for validity.
for (const Scope &scope : mTokenizer->getSymbolDatabase()->scopeList) {
if (!(scope.type == Scope::eIf || scope.isLoopScope()))
continue;
const Token* const tok = scope.classDef;
const Token* startOfCondition = tok->next();
if (scope.type == Scope::eDo)
startOfCondition = startOfCondition->link()->tokAt(2);
if (!startOfCondition) // ticket #6626 invalid code
continue;
const Token* endOfCondition = startOfCondition->link();
if (!endOfCondition)
continue;
// For "for" loops, only search between the two semicolons
if (scope.type == Scope::eFor) {
startOfCondition = Token::findsimplematch(tok->tokAt(2), ";", endOfCondition);
if (!startOfCondition)
continue;
endOfCondition = Token::findsimplematch(startOfCondition->next(), ";", endOfCondition);
if (!endOfCondition)
continue;
}
// Only consider conditions composed of all "&&" terms and
// conditions composed of all "||" terms
const bool isOrExpression =
Token::findsimplematch(startOfCondition, "||", endOfCondition) != nullptr;
const bool isAndExpression =
Token::findsimplematch(startOfCondition, "&&", endOfCondition) != nullptr;
// Look for a check of the validity of an iterator
const Token* validityCheckTok = nullptr;
if (!isOrExpression && isAndExpression) {
validityCheckTok =
Token::findmatch(startOfCondition, "&& %var% != %name% . end|rend|cend|crend ( )", endOfCondition);
} else if (isOrExpression && !isAndExpression) {
validityCheckTok =
Token::findmatch(startOfCondition, "%oror% %var% == %name% . end|rend|cend|crend ( )", endOfCondition);
}
if (!validityCheckTok)
continue;
const int iteratorVarId = validityCheckTok->next()->varId();
// If the iterator dereference is to the left of the check for
// the iterator's validity, report an error.
const Token* const dereferenceTok =
Token::findmatch(startOfCondition, "* %varid%", validityCheckTok, iteratorVarId);
if (dereferenceTok)
dereferenceInvalidIteratorError(dereferenceTok, dereferenceTok->strAt(1));
}
}
void CheckStl::checkDereferenceInvalidIterator2()
{
const bool printInconclusive = (mSettings->certainty.isEnabled(Certainty::inconclusive));
logChecker("CheckStl::checkDereferenceInvalidIterator2");
for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
if (Token::Match(tok, "sizeof|decltype|typeid|typeof (")) {
tok = tok->next()->link();
continue;
}
if (Token::Match(tok, "%assign%"))
continue;
std::vector<ValueFlow::Value> contValues;
std::copy_if(tok->values().cbegin(), tok->values().cend(), std::back_inserter(contValues), [&](const ValueFlow::Value& value) {
if (value.isImpossible())
return false;
if (!printInconclusive && value.isInconclusive())
return false;
return value.isContainerSizeValue();
});
// Can iterator point to END or before START?
for (const ValueFlow::Value& value:tok->values()) {
if (value.isImpossible())
continue;
if (!printInconclusive && value.isInconclusive())
continue;
if (!value.isIteratorValue())
continue;
bool isInvalidIterator = false;
const ValueFlow::Value* cValue = nullptr;
if (value.isIteratorEndValue() && value.intvalue >= 0) {
isInvalidIterator = value.intvalue > 0;
} else if (value.isIteratorStartValue() && value.intvalue < 0) {
isInvalidIterator = true;
} else {
auto it = std::find_if(contValues.cbegin(), contValues.cend(), [&](const ValueFlow::Value& c) {
if (value.path != c.path)
return false;
if (value.isIteratorStartValue() && value.intvalue >= c.intvalue)
return true;
if (value.isIteratorEndValue() && -value.intvalue > c.intvalue)
return true;
return false;
});
if (it == contValues.end())
continue;
cValue = &*it;
if (value.isIteratorStartValue() && value.intvalue > cValue->intvalue)
isInvalidIterator = true;
}
bool inconclusive = false;
bool unknown = false;
const Token* emptyAdvance = nullptr;
const Token* advanceIndex = nullptr;
if (cValue && cValue->intvalue == 0) {
if (Token::Match(tok->astParent(), "+|-") && astIsIntegral(tok->astSibling(), false)) {
if (tok->astSibling() && tok->astSibling()->hasKnownIntValue()) {
if (tok->astSibling()->values().front().intvalue == 0)
continue;
} else {
advanceIndex = tok->astSibling();
}
emptyAdvance = tok->astParent();
} else if (Token::Match(tok->astParent(), "++|--")) {
emptyAdvance = tok->astParent();
}
}
if (!CheckNullPointer::isPointerDeRef(tok, unknown, mSettings) && !isInvalidIterator && !emptyAdvance) {
if (!unknown)
continue;
inconclusive = true;
}
if (cValue) {
const ValueFlow::Value& lValue = getLifetimeIteratorValue(tok, cValue->path);
assert(cValue->isInconclusive() || value.isInconclusive() || lValue.isLifetimeValue());
if (!lValue.isLifetimeValue())
continue;
if (emptyAdvance)
outOfBoundsError(emptyAdvance,
lValue.tokvalue->expressionString(),
cValue,
advanceIndex ? advanceIndex->expressionString() : emptyString,
nullptr);
else
outOfBoundsError(tok, lValue.tokvalue->expressionString(), cValue, tok->expressionString(), &value);
} else {
dereferenceInvalidIteratorError(tok, &value, inconclusive);
}
}
}
}
void CheckStl::dereferenceInvalidIteratorError(const Token* tok, const ValueFlow::Value *value, bool inconclusive)
{
const std::string& varname = tok ? tok->expressionString() : "var";
const std::string errmsgcond("$symbol:" + varname + '\n' + ValueFlow::eitherTheConditionIsRedundant(value ? value->condition : nullptr) + " or there is possible dereference of an invalid iterator: $symbol.");
if (!tok || !value) {
reportError(tok, Severity::error, "derefInvalidIterator", "Dereference of an invalid iterator", CWE825, Certainty::normal);
reportError(tok, Severity::warning, "derefInvalidIteratorRedundantCheck", errmsgcond, CWE825, Certainty::normal);
return;
}
if (!mSettings->isEnabled(value, inconclusive))
return;
const ErrorPath errorPath = getErrorPath(tok, value, "Dereference of an invalid iterator");
if (value->condition) {
reportError(errorPath, Severity::warning, "derefInvalidIteratorRedundantCheck", errmsgcond, CWE825, (inconclusive || value->isInconclusive()) ? Certainty::inconclusive : Certainty::normal);
} else {
std::string errmsg = std::string(value->isKnown() ? "Dereference" : "Possible dereference") + " of an invalid iterator";
if (!varname.empty())
errmsg = "$symbol:" + varname + '\n' + errmsg + ": $symbol";
reportError(errorPath,
value->isKnown() ? Severity::error : Severity::warning,
"derefInvalidIterator",
errmsg,
CWE825, (inconclusive || value->isInconclusive()) ? Certainty::inconclusive : Certainty::normal);
}
}
void CheckStl::dereferenceInvalidIteratorError(const Token* deref, const std::string &iterName)
{
reportError(deref, Severity::warning,
"derefInvalidIterator",
"$symbol:" + iterName + "\n"
"Possible dereference of an invalid iterator: $symbol\n"
"Possible dereference of an invalid iterator: $symbol. Make sure to check that the iterator is valid before dereferencing it - not after.", CWE825, Certainty::normal);
}
void CheckStl::useStlAlgorithmError(const Token *tok, const std::string &algoName)
{
reportError(tok, Severity::style, "useStlAlgorithm",
"Consider using " + algoName + " algorithm instead of a raw loop.", CWE398, Certainty::normal);
}
static bool isEarlyExit(const Token *start)
{
if (start->str() != "{")
return false;
const Token *endToken = start->link();
const Token *tok = Token::findmatch(start, "return|throw|break", endToken);
if (!tok)
return false;
const Token *endStatement = Token::findsimplematch(tok, "; }", endToken);
if (!endStatement)
return false;
if (endStatement->next() != endToken)
return false;
return true;
}
static const Token *singleStatement(const Token *start)
{
if (start->str() != "{")
return nullptr;
const Token *endToken = start->link();
const Token *endStatement = Token::findsimplematch(start->next(), ";");
if (!Token::simpleMatch(endStatement, "; }"))
return nullptr;
if (endStatement->next() != endToken)
return nullptr;
return endStatement;
}
static const Token *singleAssignInScope(const Token *start, nonneg int varid, bool &input, const Settings* settings)
{
const Token *endStatement = singleStatement(start);
if (!endStatement)
return nullptr;
if (!Token::Match(start->next(), "%var% %assign%"))
return nullptr;
const Token *assignTok = start->tokAt(2);
if (isVariableChanged(assignTok->next(), endStatement, assignTok->astOperand1()->varId(), /*globalvar*/ false, settings, /*cpp*/ true))
return nullptr;
if (isVariableChanged(assignTok->next(), endStatement, varid, /*globalvar*/ false, settings, /*cpp*/ true))
return nullptr;
input = Token::findmatch(assignTok->next(), "%varid%", endStatement, varid) || !Token::Match(start->next(), "%var% =");
return assignTok;
}
static const Token *singleMemberCallInScope(const Token *start, nonneg int varid, bool &input, const Settings* settings)
{
if (start->str() != "{")
return nullptr;
const Token *endToken = start->link();
if (!Token::Match(start->next(), "%var% . %name% ("))
return nullptr;
if (!Token::simpleMatch(start->linkAt(4), ") ; }"))
return nullptr;
const Token *endStatement = start->linkAt(4)->next();
if (endStatement->next() != endToken)
return nullptr;
const Token *dotTok = start->tokAt(2);
if (!Token::findmatch(dotTok->tokAt(2), "%varid%", endStatement, varid))
return nullptr;
input = Token::Match(start->next(), "%var% . %name% ( %varid% )", varid);
if (isVariableChanged(dotTok->next(), endStatement, dotTok->astOperand1()->varId(), /*globalvar*/ false, settings, /*cpp*/ true))
return nullptr;
return dotTok;
}
static const Token *singleIncrementInScope(const Token *start, nonneg int varid, bool &input)
{
if (start->str() != "{")
return nullptr;
const Token *varTok = nullptr;
if (Token::Match(start->next(), "++ %var% ; }"))
varTok = start->tokAt(2);
else if (Token::Match(start->next(), "%var% ++ ; }"))
varTok = start->tokAt(1);
if (!varTok)
return nullptr;
input = varTok->varId() == varid;
return varTok;
}
static const Token *singleConditionalInScope(const Token *start, nonneg int varid, const Settings* settings)
{
if (start->str() != "{")
return nullptr;
const Token *endToken = start->link();
if (!Token::simpleMatch(start->next(), "if ("))
return nullptr;
if (!Token::simpleMatch(start->linkAt(2), ") {"))
return nullptr;
const Token *bodyTok = start->linkAt(2)->next();
const Token *endBodyTok = bodyTok->link();
if (!Token::simpleMatch(endBodyTok, "} }"))
return nullptr;
if (endBodyTok->next() != endToken)
return nullptr;
if (!Token::findmatch(start, "%varid%", bodyTok, varid))
return nullptr;
if (isVariableChanged(start, bodyTok, varid, /*globalvar*/ false, settings, /*cpp*/ true))
return nullptr;
return bodyTok;
}
static bool addByOne(const Token *tok, nonneg int varid)
{
if (Token::Match(tok, "+= %any% ;") &&
tok->tokAt(1)->hasKnownIntValue() &&
tok->tokAt(1)->getValue(1)) {
return true;
}
if (Token::Match(tok, "= %varid% + %any% ;", varid) &&
tok->tokAt(3)->hasKnownIntValue() &&
tok->tokAt(3)->getValue(1)) {
return true;
}
return false;
}
static bool accumulateBoolLiteral(const Token *tok, nonneg int varid)
{
if (Token::Match(tok, "%assign% %bool% ;") &&
tok->tokAt(1)->hasKnownIntValue()) {
return true;
}
if (Token::Match(tok, "= %varid% %oror%|%or%|&&|& %bool% ;", varid) &&
tok->tokAt(3)->hasKnownIntValue()) {
return true;
}
return false;
}
static bool accumulateBool(const Token *tok, nonneg int varid)
{
// Missing %oreq% so we have to check both manually
if (Token::simpleMatch(tok, "&=") || Token::simpleMatch(tok, "|=")) {
return true;
}
if (Token::Match(tok, "= %varid% %oror%|%or%|&&|&", varid)) {
return true;
}
return false;
}
static bool hasVarIds(const Token *tok, nonneg int var1, nonneg int var2)
{
if (tok->astOperand1()->varId() == tok->astOperand2()->varId())
return false;
if (tok->astOperand1()->varId() == var1 || tok->astOperand1()->varId() == var2) {
if (tok->astOperand2()->varId() == var1 || tok->astOperand2()->varId() == var2) {
return true;
}
}
return false;
}
static std::string flipMinMax(const std::string &algo)
{
if (algo == "std::max_element")
return "std::min_element";
if (algo == "std::min_element")
return "std::max_element";
return algo;
}
static std::string minmaxCompare(const Token *condTok, nonneg int loopVar, nonneg int assignVar, bool invert = false)
{
if (!Token::Match(condTok, "<|<=|>=|>"))
return "std::accumulate";
if (!hasVarIds(condTok, loopVar, assignVar))
return "std::accumulate";
std::string algo = "std::max_element";
if (Token::Match(condTok, "<|<="))
algo = "std::min_element";
if (condTok->astOperand1()->varId() == assignVar)
algo = flipMinMax(algo);
if (invert)
algo = flipMinMax(algo);
return algo;
}
namespace {
struct LoopAnalyzer {
const Token* bodyTok = nullptr;
const Token* loopVar = nullptr;
const Settings* settings = nullptr;
std::set<nonneg int> varsChanged;
explicit LoopAnalyzer(const Token* tok, const Settings* psettings)
: bodyTok(tok->next()->link()->next()), settings(psettings)
{
const Token* splitTok = tok->next()->astOperand2();
if (Token::simpleMatch(splitTok, ":") && splitTok->previous()->varId() != 0) {
loopVar = splitTok->previous();
}
if (valid()) {
findChangedVariables();
}
}
bool isLoopVarChanged() const {
return varsChanged.count(loopVar->varId()) > 0;
}
bool isModified(const Token* tok) const
{
if (tok->variable() && tok->variable()->isConst())
return false;
int n = 1 + (astIsPointer(tok) ? 1 : 0);
for (int i = 0; i < n; i++) {
bool inconclusive = false;
if (isVariableChangedByFunctionCall(tok, i, settings, &inconclusive))
return true;
if (inconclusive)
return true;
if (isVariableChanged(tok, i, settings, true))
return true;
}
return false;
}
template<class Predicate, class F>
void findTokens(Predicate pred, F f) const
{
for (const Token* tok = bodyTok; precedes(tok, bodyTok->link()); tok = tok->next()) {
if (pred(tok))
f(tok);
}
}
template<class Predicate>
const Token* findToken(Predicate pred) const
{
for (const Token* tok = bodyTok; precedes(tok, bodyTok->link()); tok = tok->next()) {
if (pred(tok))
return tok;
}
return nullptr;
}
bool hasGotoOrBreak() const
{
return findToken([](const Token* tok) {
return Token::Match(tok, "goto|break");
});
}
bool valid() const {
return bodyTok && loopVar;
}
std::string findAlgo() const
{
if (!valid())
return "";
bool loopVarChanged = isLoopVarChanged();
if (!loopVarChanged && varsChanged.empty()) {
if (hasGotoOrBreak())
return "";
bool alwaysTrue = true;
bool alwaysFalse = true;
auto hasReturn = [](const Token* tok) {
return Token::simpleMatch(tok, "return");
};
findTokens(hasReturn, [&](const Token* tok) {
const Token* returnTok = tok->astOperand1();
if (!returnTok || !returnTok->hasKnownIntValue() || !astIsBool(returnTok)) {
alwaysTrue = false;
alwaysFalse = false;
return;
}
(returnTok->values().front().intvalue ? alwaysTrue : alwaysFalse) &= true;
(returnTok->values().front().intvalue ? alwaysFalse : alwaysTrue) &= false;
});
if (alwaysTrue == alwaysFalse)
return "";
if (alwaysTrue)
return "std::any_of";
return "std::all_of or std::none_of";
}
return "";
}
bool isLocalVar(const Variable* var) const
{
if (!var)
return false;
if (var->isPointer() || var->isReference())
return false;
if (var->declarationId() == loopVar->varId())
return false;
const Scope* scope = var->scope();
return scope && scope->isNestedIn(bodyTok->scope());
}
private:
void findChangedVariables()
{
std::set<nonneg int> vars;
for (const Token* tok = bodyTok; precedes(tok, bodyTok->link()); tok = tok->next()) {
if (tok->varId() == 0)
continue;
if (vars.count(tok->varId()) > 0)
continue;
if (isLocalVar(tok->variable())) {
vars.insert(tok->varId());
continue;
}
if (!isModified(tok))
continue;
varsChanged.insert(tok->varId());
vars.insert(tok->varId());
}
}
};
} // namespace
void CheckStl::useStlAlgorithm()
{
if (!mSettings->severity.isEnabled(Severity::style))
return;
logChecker("CheckStl::useStlAlgorithm"); // style
auto checkAssignee = [](const Token* tok) {
if (astIsBool(tok)) // std::accumulate is not a good fit for bool values, std::all/any/none_of return early
return false;
return !astIsContainer(tok); // don't warn for containers, where overloaded operators can be costly
};
auto isConditionWithoutSideEffects = [this](const Token* tok) -> bool {
if (!Token::simpleMatch(tok, "{") || !Token::simpleMatch(tok->previous(), ")"))
return false;
return isConstExpression(tok->previous()->link()->astOperand2(), mSettings->library, true);
};
for (const Scope *function : mTokenizer->getSymbolDatabase()->functionScopes) {
for (const Token *tok = function->bodyStart; tok != function->bodyEnd; tok = tok->next()) {
// Parse range-based for loop
if (!Token::simpleMatch(tok, "for ("))
continue;
if (!Token::simpleMatch(tok->next()->link(), ") {"))
continue;
LoopAnalyzer a{tok, mSettings};
std::string algoName = a.findAlgo();
if (!algoName.empty()) {
useStlAlgorithmError(tok, algoName);
continue;
}
const Token *bodyTok = tok->next()->link()->next();
const Token *splitTok = tok->next()->astOperand2();
const Token* loopVar{};
bool isIteratorLoop = false;
if (Token::simpleMatch(splitTok, ":")) {
loopVar = splitTok->previous();
if (loopVar->varId() == 0)
continue;
if (Token::simpleMatch(splitTok->astOperand2(), "{"))
continue;
}
else { // iterator-based loop?
const Token* initTok = getInitTok(tok);
const Token* condTok = getCondTok(tok);
const Token* stepTok = getStepTok(tok);
if (!initTok || !condTok || !stepTok)
continue;
loopVar = Token::Match(condTok, "%comp%") ? condTok->astOperand1() : nullptr;
if (!Token::Match(loopVar, "%var%") || !loopVar->valueType() || loopVar->valueType()->type != ValueType::Type::ITERATOR)
continue;
if (!Token::simpleMatch(initTok, "=") || !Token::Match(initTok->astOperand1(), "%varid%", loopVar->varId()))
continue;
if (!stepTok->isIncDecOp())
continue;
isIteratorLoop = true;
}
// Check for single assignment
bool useLoopVarInAssign;
const Token *assignTok = singleAssignInScope(bodyTok, loopVar->varId(), useLoopVarInAssign, mSettings);
if (assignTok) {
if (!checkAssignee(assignTok->astOperand1()))
continue;
const int assignVarId = assignTok->astOperand1()->varId();
std::string algo;
if (assignVarId == loopVar->varId()) {
if (useLoopVarInAssign)
algo = "std::transform";
else if (Token::Match(assignTok->next(), "%var%|%bool%|%num%|%char% ;"))
algo = "std::fill";
else if (Token::Match(assignTok->next(), "%name% ( )"))
algo = "std::generate";
else
algo = "std::fill or std::generate";
} else {
if (addByOne(assignTok, assignVarId))
algo = "std::distance";
else if (accumulateBool(assignTok, assignVarId))
algo = "std::any_of, std::all_of, std::none_of, or std::accumulate";
else if (Token::Match(assignTok, "= %var% <|<=|>=|> %var% ? %var% : %var%") && hasVarIds(assignTok->tokAt(6), loopVar->varId(), assignVarId))
algo = minmaxCompare(assignTok->tokAt(2), loopVar->varId(), assignVarId, assignTok->tokAt(5)->varId() == assignVarId);
else
algo = "std::accumulate";
}
useStlAlgorithmError(assignTok, algo);
continue;
}
// Check for container calls
bool useLoopVarInMemCall;
const Token *memberAccessTok = singleMemberCallInScope(bodyTok, loopVar->varId(), useLoopVarInMemCall, mSettings);
if (memberAccessTok && !isIteratorLoop) {
const Token *memberCallTok = memberAccessTok->astOperand2();
const int contVarId = memberAccessTok->astOperand1()->varId();
if (contVarId == loopVar->varId())
continue;
if (memberCallTok->str() == "push_back" ||
memberCallTok->str() == "push_front" ||
memberCallTok->str() == "emplace_back") {
std::string algo;
if (useLoopVarInMemCall)
algo = "std::copy";
else
algo = "std::transform";
useStlAlgorithmError(memberCallTok, algo);
}
continue;
}
// Check for increment in loop
bool useLoopVarInIncrement;
const Token *incrementTok = singleIncrementInScope(bodyTok, loopVar->varId(), useLoopVarInIncrement);
if (incrementTok) {
std::string algo;
if (useLoopVarInIncrement)
algo = "std::transform";
else
algo = "std::distance";
useStlAlgorithmError(incrementTok, algo);
continue;
}
// Check for conditionals
const Token *condBodyTok = singleConditionalInScope(bodyTok, loopVar->varId(), mSettings);
if (condBodyTok) {
// Check for single assign
assignTok = singleAssignInScope(condBodyTok, loopVar->varId(), useLoopVarInAssign, mSettings);
if (assignTok) {
if (!checkAssignee(assignTok->astOperand1()))
continue;
const int assignVarId = assignTok->astOperand1()->varId();
std::string algo;
if (assignVarId == loopVar->varId()) {
if (useLoopVarInAssign)
algo = "std::transform";
else
algo = "std::replace_if";
} else {
if (addByOne(assignTok, assignVarId))
algo = "std::count_if";
else if (accumulateBoolLiteral(assignTok, assignVarId))
algo = "std::any_of, std::all_of, std::none_of, or std::accumulate";
else if (assignTok->str() != "=")
algo = "std::accumulate";
else if (isConditionWithoutSideEffects(condBodyTok))
algo = "std::any_of, std::all_of, std::none_of";
else
continue;
}
useStlAlgorithmError(assignTok, algo);
continue;
}
// Check for container call
memberAccessTok = singleMemberCallInScope(condBodyTok, loopVar->varId(), useLoopVarInMemCall, mSettings);
if (memberAccessTok) {
const Token *memberCallTok = memberAccessTok->astOperand2();
const int contVarId = memberAccessTok->astOperand1()->varId();
if (contVarId == loopVar->varId())
continue;
if (memberCallTok->str() == "push_back" ||
memberCallTok->str() == "push_front" ||
memberCallTok->str() == "emplace_back") {
if (useLoopVarInMemCall)
useStlAlgorithmError(memberAccessTok, "std::copy_if");
// There is no transform_if to suggest
}
continue;
}
// Check for increment in loop
incrementTok = singleIncrementInScope(condBodyTok, loopVar->varId(), useLoopVarInIncrement);
if (incrementTok) {
std::string algo;
if (useLoopVarInIncrement)
algo = "std::transform";
else
algo = "std::count_if";
useStlAlgorithmError(incrementTok, algo);
continue;
}
// Check early return
if (isEarlyExit(condBodyTok)) {
const Token *loopVar2 = Token::findmatch(condBodyTok, "%varid%", condBodyTok->link(), loopVar->varId());
std::string algo;
if (loopVar2 ||
(isIteratorLoop && loopVar->variable() && precedes(loopVar->variable()->nameToken(), tok))) // iterator declared outside the loop
algo = "std::find_if";
else
algo = "std::any_of";
useStlAlgorithmError(condBodyTok, algo);
continue;
}
}
}
}
}
void CheckStl::knownEmptyContainerError(const Token *tok, const std::string& algo)
{
const std::string var = tok ? tok->expressionString() : std::string("var");
std::string msg;
if (astIsIterator(tok)) {
msg = "Using " + algo + " with iterator '" + var + "' that is always empty.";
} else {
msg = "Iterating over container '" + var + "' that is always empty.";
}
reportError(tok, Severity::style,
"knownEmptyContainer",
msg, CWE398, Certainty::normal);
}
static bool isKnownEmptyContainer(const Token* tok)
{
if (!tok)
return false;
return std::any_of(tok->values().begin(), tok->values().end(), [&](const ValueFlow::Value& v) {
if (!v.isKnown())
return false;
if (!v.isContainerSizeValue())
return false;
if (v.intvalue != 0)
return false;
return true;
});
}
void CheckStl::knownEmptyContainer()
{
if (!mSettings->severity.isEnabled(Severity::style))
return;
logChecker("CheckStl::knownEmptyContainer"); // style
for (const Scope *function : mTokenizer->getSymbolDatabase()->functionScopes) {
for (const Token *tok = function->bodyStart; tok != function->bodyEnd; tok = tok->next()) {
if (!Token::Match(tok, "%name% ( !!)"))
continue;
// Parse range-based for loop
if (tok->str() == "for") {
if (!Token::simpleMatch(tok->next()->link(), ") {"))
continue;
const Token *splitTok = tok->next()->astOperand2();
if (!Token::simpleMatch(splitTok, ":"))
continue;
const Token* contTok = splitTok->astOperand2();
if (!isKnownEmptyContainer(contTok))
continue;
knownEmptyContainerError(contTok, emptyString);
} else {
const std::vector<const Token *> args = getArguments(tok);
if (args.empty())
continue;
for (int argnr = 1; argnr <= args.size(); ++argnr) {
const Library::ArgumentChecks::IteratorInfo *i = mSettings->library.getArgIteratorInfo(tok, argnr);
if (!i)
continue;
const Token * const argTok = args[argnr - 1];
if (!isKnownEmptyContainer(argTok))
continue;
knownEmptyContainerError(argTok, tok->str());
break;
}
}
}
}
}
static bool isMutex(const Variable* var)
{
const Token* tok = Token::typeDecl(var->nameToken()).first;
return Token::Match(tok, "std :: mutex|recursive_mutex|timed_mutex|recursive_timed_mutex|shared_mutex");
}
static bool isLockGuard(const Variable* var)
{
const Token* tok = Token::typeDecl(var->nameToken()).first;
return Token::Match(tok, "std :: lock_guard|unique_lock|scoped_lock|shared_lock");
}
static bool isLocalMutex(const Variable* var, const Scope* scope)
{
if (!var)
return false;
if (isLockGuard(var))
return false;
return !var->isReference() && !var->isRValueReference() && !var->isStatic() && var->scope() == scope;
}
void CheckStl::globalLockGuardError(const Token* tok)
{
reportError(tok, Severity::warning,
"globalLockGuard",
"Lock guard is defined globally. Lock guards are intended to be local. A global lock guard could lead to a deadlock since it won't unlock until the end of the program.", CWE833, Certainty::normal);
}
void CheckStl::localMutexError(const Token* tok)
{
reportError(tok, Severity::warning,
"localMutex",
"The lock is ineffective because the mutex is locked at the same scope as the mutex itself.", CWE667, Certainty::normal);
}
void CheckStl::checkMutexes()
{
if (!mSettings->severity.isEnabled(Severity::warning))
return;
logChecker("CheckStl::checkMutexes"); // warning
for (const Scope *function : mTokenizer->getSymbolDatabase()->functionScopes) {
std::set<nonneg int> checkedVars;
for (const Token *tok = function->bodyStart; tok != function->bodyEnd; tok = tok->next()) {
if (!Token::Match(tok, "%var%"))
continue;
const Variable* var = tok->variable();
if (!var)
continue;
if (Token::Match(tok, "%var% . lock ( )")) {
if (!isMutex(var))
continue;
if (!checkedVars.insert(var->declarationId()).second)
continue;
if (isLocalMutex(var, tok->scope()))
localMutexError(tok);
} else if (Token::Match(tok, "%var% (|{ %var% )|}|,")) {
if (!isLockGuard(var))
continue;
const Variable* mvar = tok->tokAt(2)->variable();
if (!mvar)
continue;
if (!checkedVars.insert(mvar->declarationId()).second)
continue;
if (var->isStatic() || var->isGlobal())
globalLockGuardError(tok);
else if (isLocalMutex(mvar, tok->scope()))
localMutexError(tok);
}
}
}
}
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