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cppcheck/lib/checkuninitvar.cpp

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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2015 Daniel Marjamäki and 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 "checkuninitvar.h"
#include "astutils.h"
#include "mathlib.h"
#include "checknullpointer.h" // CheckNullPointer::parseFunctionCall
#include "symboldatabase.h"
#include <algorithm>
#include <map>
#include <cassert>
#include <stack>
//---------------------------------------------------------------------------
// Register this check class (by creating a static instance of it)
namespace {
CheckUninitVar instance;
}
//---------------------------------------------------------------------------
void CheckUninitVar::check()
{
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
std::list<Scope>::const_iterator scope;
// check every executable scope
for (scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) {
if (scope->isExecutable()) {
checkScope(&*scope);
}
}
}
void CheckUninitVar::checkScope(const Scope* scope)
{
for (std::list<Variable>::const_iterator i = scope->varlist.begin(); i != scope->varlist.end(); ++i) {
if ((_tokenizer->isCPP() && i->type() && !i->isPointer() && i->type()->needInitialization != Type::True) ||
i->isStatic() || i->isExtern() || i->isReference())
continue;
// don't warn for try/catch exception variable
if (i->isThrow())
continue;
if (i->nameToken()->strAt(1) == "(" || i->nameToken()->strAt(1) == "{")
continue;
if (Token::Match(i->nameToken(), "%name% =")) { // Variable is initialized, but Rhs might be not
checkRhs(i->nameToken(), *i, NO_ALLOC, 0U, "");
continue;
}
if (Token::Match(i->nameToken(), "%name% ) (") && Token::simpleMatch(i->nameToken()->linkAt(2), ") =")) { // Function pointer is initialized, but Rhs might be not
checkRhs(i->nameToken()->linkAt(2)->next(), *i, NO_ALLOC, 0U, "");
continue;
}
if (i->isArray()) {
const Token *tok = i->nameToken()->next();
while (Token::simpleMatch(tok->link(), "] ["))
tok = tok->link()->next();
if (Token::simpleMatch(tok->link(), "] ="))
continue;
}
bool stdtype = _tokenizer->isC();
const Token* tok = i->typeStartToken();
for (; tok != i->nameToken() && tok->str() != "<"; tok = tok->next()) {
if (tok->isStandardType())
stdtype = true;
}
if (i->isArray() && !stdtype)
continue;
while (tok && tok->str() != ";")
tok = tok->next();
if (!tok)
continue;
if (i->isArray()) {
Alloc alloc = ARRAY;
checkScopeForVariable(tok, *i, nullptr, nullptr, &alloc, "");
continue;
}
if (stdtype || i->isPointer()) {
Alloc alloc = NO_ALLOC;
checkScopeForVariable(tok, *i, nullptr, nullptr, &alloc, "");
}
if (i->type())
checkStruct(tok, *i);
}
if (scope->function) {
for (unsigned int i = 0; i < scope->function->argCount(); i++) {
const Variable *arg = scope->function->getArgumentVar(i);
if (arg && arg->declarationId() && Token::Match(arg->typeStartToken(), "struct| %type% * %name% [,)]")) {
// Treat the pointer as initialized until it is assigned by malloc
for (const Token *tok = scope->classStart; tok != scope->classEnd; tok = tok->next()) {
if (Token::Match(tok, "[;{}] %varid% = %name% (", arg->declarationId()) &&
_settings->library.returnuninitdata.count(tok->strAt(3)) == 1U) {
if (arg->typeStartToken()->str() == "struct")
checkStruct(tok, *arg);
else if (arg->typeStartToken()->isStandardType()) {
Alloc alloc = NO_ALLOC;
checkScopeForVariable(tok->next(), *arg, nullptr, nullptr, &alloc, "");
}
}
}
}
}
}
}
void CheckUninitVar::checkStruct(const Token *tok, const Variable &structvar)
{
const Token *typeToken = structvar.typeStartToken();
if (typeToken->str() == "struct")
typeToken = typeToken->next();
const SymbolDatabase * symbolDatabase = _tokenizer->getSymbolDatabase();
for (std::size_t j = 0U; j < symbolDatabase->classAndStructScopes.size(); ++j) {
const Scope *scope2 = symbolDatabase->classAndStructScopes[j];
if (scope2->className == typeToken->str() && scope2->numConstructors == 0U) {
for (std::list<Variable>::const_iterator it = scope2->varlist.begin(); it != scope2->varlist.end(); ++it) {
const Variable &var = *it;
if (var.hasDefault() || var.isArray() || (!_tokenizer->isC() && var.isClass() && (!var.type() || var.type()->needInitialization != Type::True)))
continue;
// is the variable declared in a inner union?
bool innerunion = false;
for (std::list<Scope>::const_iterator it2 = symbolDatabase->scopeList.begin(); it2 != symbolDatabase->scopeList.end(); ++it2) {
const Scope &innerScope = *it2;
if (innerScope.type == Scope::eUnion && innerScope.nestedIn == scope2) {
if (var.typeStartToken()->linenr() >= innerScope.classStart->linenr() &&
var.typeStartToken()->linenr() <= innerScope.classEnd->linenr()) {
innerunion = true;
break;
}
}
}
if (!innerunion) {
Alloc alloc = NO_ALLOC;
const Token *tok2 = tok;
if (tok->str() == "}")
tok2 = tok2->next();
checkScopeForVariable(tok2, structvar, nullptr, nullptr, &alloc, var.name());
}
}
}
}
}
static void conditionAlwaysTrueOrFalse(const Token *tok, const std::map<unsigned int, int> &variableValue, bool *alwaysTrue, bool *alwaysFalse)
{
assert(Token::simpleMatch(tok, "if ("));
const Token *vartok = tok->tokAt(2);
const bool NOT(vartok->str() == "!");
if (NOT)
vartok = vartok->next();
while (Token::Match(vartok, "%name% . %name%"))
vartok = vartok->tokAt(2);
std::map<unsigned int, int>::const_iterator it = variableValue.find(vartok->varId());
if (it == variableValue.end())
return;
// always true
if (Token::Match(vartok, "%name% %oror%|)")) {
if (NOT)
*alwaysTrue = bool(it->second == 0);
else
*alwaysTrue = bool(it->second != 0);
} else if (Token::Match(vartok, "%name% == %num% %or%|)")) {
*alwaysTrue = bool(it->second == MathLib::toLongNumber(vartok->strAt(2)));
} else if (Token::Match(vartok, "%name% != %num% %or%|)")) {
*alwaysTrue = bool(it->second != MathLib::toLongNumber(vartok->strAt(2)));
}
// always false
if (Token::Match(vartok, "%name% &&|)")) {
if (NOT)
*alwaysFalse = bool(it->second != 0);
else
*alwaysFalse = bool(it->second == 0);
} else if (Token::Match(vartok, "%name% == %num% &&|)")) {
*alwaysFalse = bool(it->second != MathLib::toLongNumber(vartok->strAt(2)));
} else if (Token::Match(vartok, "%name% != %num% &&|)")) {
*alwaysFalse = bool(it->second == MathLib::toLongNumber(vartok->strAt(2)));
}
}
static bool isVariableUsed(const Token *tok, const Variable& var)
{
if (!tok)
return false;
if (tok->str() == "&" && !tok->astOperand2())
return false;
if (tok->isConstOp())
return isVariableUsed(tok->astOperand1(),var) || isVariableUsed(tok->astOperand2(),var);
if (var.isArray()) {
const Token *parent = tok->astParent();
while (Token::Match(parent, "[?:]"))
parent = parent->astParent();
// no dereference, then array is not "used"
if (!Token::Match(parent, "*|["))
return false;
const Token *parent2 = parent->astParent();
// TODO: handle function calls. There is a TODO assertion in TestUninitVar::uninitvar_arrays
return !parent2 || parent2->isConstOp() || (parent2->str() == "=" && parent2->astOperand2() == parent);
}
return (tok->varId() == var.declarationId());
}
bool CheckUninitVar::checkScopeForVariable(const Token *tok, const Variable& var, bool * const possibleInit, bool * const noreturn, Alloc* const alloc, const std::string &membervar)
{
const bool suppressErrors(possibleInit && *possibleInit);
const bool printDebug = _settings->debugwarnings;
if (possibleInit)
*possibleInit = false;
unsigned int number_of_if = 0;
if (var.declarationId() == 0U)
return true;
// variable values
std::map<unsigned int, int> variableValue;
static const int NOT_ZERO = (1<<30); // special variable value
for (; tok; tok = tok->next()) {
// End of scope..
if (tok->str() == "}") {
if (number_of_if && possibleInit)
*possibleInit = true;
// might be a noreturn function..
if (_tokenizer->IsScopeNoReturn(tok)) {
if (noreturn)
*noreturn = true;
return false;
}
break;
}
// Unconditional inner scope or try..
if (tok->str() == "{" && Token::Match(tok->previous(), ";|{|}|try")) {
if (checkScopeForVariable(tok->next(), var, possibleInit, noreturn, alloc, membervar))
return true;
tok = tok->link();
continue;
}
// assignment with nonzero constant..
if (Token::Match(tok->previous(), "[;{}] %var% = - %name% ;"))
variableValue[tok->varId()] = NOT_ZERO;
// Inner scope..
else if (Token::simpleMatch(tok, "if (")) {
bool alwaysTrue = false;
bool alwaysFalse = false;
conditionAlwaysTrueOrFalse(tok, variableValue, &alwaysTrue, &alwaysFalse);
// initialization / usage in condition..
if (!alwaysTrue && checkIfForWhileHead(tok->next(), var, suppressErrors, bool(number_of_if == 0), *alloc, membervar))
return true;
// checking if a not-zero variable is zero => bail out
unsigned int condVarId = 0, condVarValue = 0;
const Token *condVarTok = nullptr;
if (Token::simpleMatch(tok, "if (") &&
astIsVariableComparison(tok->next()->astOperand2(), "!=", "0", &condVarTok)) {
std::map<unsigned int,int>::const_iterator it = variableValue.find(condVarTok->varId());
if (it != variableValue.end() && it->second == NOT_ZERO)
return true; // this scope is not fully analysed => return true
else {
condVarId = condVarTok->varId();
condVarValue = NOT_ZERO;
}
}
// goto the {
tok = tok->next()->link()->next();
if (!tok)
break;
if (tok->str() == "{") {
bool possibleInitIf(number_of_if > 0 || suppressErrors);
bool noreturnIf = false;
const bool initif = !alwaysFalse && checkScopeForVariable(tok->next(), var, &possibleInitIf, &noreturnIf, alloc, membervar);
// bail out for such code:
// if (a) x=0; // conditional initialization
// if (b) return; // cppcheck doesn't know if b can be false when a is false.
// x++; // it's possible x is always initialized
if (!alwaysTrue && noreturnIf && number_of_if > 0) {
if (printDebug) {
std::string condition;
for (const Token *tok2 = tok->linkAt(-1); tok2 != tok; tok2 = tok2->next()) {
condition += tok2->str();
if (tok2->isName() && tok2->next()->isName())
condition += ' ';
}
reportError(tok, Severity::debug, "debug", "bailout uninitialized variable checking for '" + var.name() + "'. can't determine if this condition can be false when previous condition is false: " + condition);
}
return true;
}
if (alwaysTrue && noreturnIf)
return true;
std::map<unsigned int, int> varValueIf;
if (!alwaysFalse && !initif && !noreturnIf) {
for (const Token *tok2 = tok; tok2 && tok2 != tok->link(); tok2 = tok2->next()) {
if (Token::Match(tok2, "[;{}.] %name% = - %name% ;"))
varValueIf[tok2->next()->varId()] = NOT_ZERO;
else if (Token::Match(tok2, "[;{}.] %name% = %num% ;"))
varValueIf[tok2->next()->varId()] = (int)MathLib::toLongNumber(tok2->strAt(3));
}
}
if (initif && condVarId > 0U)
variableValue[condVarId] = condVarValue ^ NOT_ZERO;
// goto the }
tok = tok->link();
if (!Token::simpleMatch(tok, "} else {")) {
if (initif || possibleInitIf) {
++number_of_if;
if (number_of_if >= 2)
return true;
}
} else {
// goto the {
tok = tok->tokAt(2);
bool possibleInitElse(number_of_if > 0 || suppressErrors);
bool noreturnElse = false;
const bool initelse = !alwaysTrue && checkScopeForVariable(tok->next(), var, &possibleInitElse, &noreturnElse, alloc, membervar);
std::map<unsigned int, int> varValueElse;
if (!alwaysTrue && !initelse && !noreturnElse) {
for (const Token *tok2 = tok; tok2 && tok2 != tok->link(); tok2 = tok2->next()) {
if (Token::Match(tok2, "[;{}.] %var% = - %name% ;"))
varValueElse[tok2->next()->varId()] = NOT_ZERO;
else if (Token::Match(tok2, "[;{}.] %var% = %num% ;"))
varValueElse[tok2->next()->varId()] = (int)MathLib::toLongNumber(tok2->strAt(3));
}
}
if (initelse && condVarId > 0U && !noreturnIf && !noreturnElse)
variableValue[condVarId] = condVarValue;
// goto the }
tok = tok->link();
if ((alwaysFalse || initif || noreturnIf) &&
(alwaysTrue || initelse || noreturnElse))
return true;
if (initif || initelse || possibleInitElse)
++number_of_if;
if (!initif && !noreturnIf)
variableValue.insert(varValueIf.begin(), varValueIf.end());
if (!initelse && !noreturnElse)
variableValue.insert(varValueElse.begin(), varValueElse.end());
}
}
}
// = { .. }
else if (Token::simpleMatch(tok, "= {")) {
// end token
const Token *end = tok->next()->link();
// If address of variable is taken in the block then bail out
if (Token::findmatch(tok->tokAt(2), "& %varid%", end, var.declarationId()))
return true;
// Skip block
tok = end;
continue;
}
// skip sizeof / offsetof
if (Token::Match(tok, "sizeof|typeof|offsetof|decltype ("))
tok = tok->next()->link();
// for/while..
else if (Token::Match(tok, "for|while (") || Token::simpleMatch(tok, "do {")) {
const bool forwhile = Token::Match(tok, "for|while (");
// is variable initialized in for-head (don't report errors yet)?
if (forwhile && checkIfForWhileHead(tok->next(), var, true, false, *alloc, membervar))
return true;
// goto the {
const Token *tok2 = forwhile ? tok->next()->link()->next() : tok->next();
if (tok2 && tok2->str() == "{") {
bool init = checkLoopBody(tok2, var, *alloc, membervar, (number_of_if > 0) || suppressErrors);
// variable is initialized in the loop..
if (init)
return true;
// is variable used in for-head?
bool initcond = false;
if (!suppressErrors) {
const Token *startCond = forwhile ? tok->next() : tok->next()->link()->tokAt(2);
initcond = checkIfForWhileHead(startCond, var, false, bool(number_of_if == 0), *alloc, membervar);
}
// goto "}"
tok = tok2->link();
// do-while => goto ")"
if (!forwhile) {
// Assert that the tokens are '} while ('
if (!Token::simpleMatch(tok, "} while (")) {
if (printDebug)
reportError(tok,Severity::debug,"","assertion failed '} while ('");
break;
}
// Goto ')'
tok = tok->linkAt(2);
if (!tok)
// bailout : invalid code / bad tokenizer
break;
if (initcond)
// variable is initialized in while-condition
return true;
}
}
}
// Unknown or unhandled inner scope
else if (Token::simpleMatch(tok, ") {") || (Token::Match(tok, "%name% {") && tok->str() != "try")) {
if (tok->str() == "struct" || tok->str() == "union") {
tok = tok->linkAt(1);
continue;
}
return true;
}
// bailout if there is ({
if (Token::simpleMatch(tok, "( {")) {
return true;
}
// bailout if there is assembler code or setjmp
if (Token::Match(tok, "asm|setjmp (")) {
return true;
}
if (tok->str() == "?") {
if (!tok->astOperand2())
return true;
const bool used1 = isVariableUsed(tok->astOperand2()->astOperand1(), var);
const bool used0 = isVariableUsed(tok->astOperand2()->astOperand2(), var);
const bool err = (number_of_if == 0) ? (used1 || used0) : (used1 && used0);
if (err)
uninitvarError(tok, var.nameToken()->str(), *alloc);
// Todo: skip expression if there is no error
return true;
}
if (Token::Match(tok, "return|break|continue|throw|goto")) {
if (noreturn)
*noreturn = true;
while (tok && tok->str() != ";") {
// variable is seen..
if (tok->varId() == var.declarationId()) {
if (!membervar.empty()) {
if (Token::Match(tok, "%name% . %name% ;|%cop%") && tok->strAt(2) == membervar)
uninitStructMemberError(tok, tok->str() + "." + membervar);
else
return true;
}
// Use variable
else if (!suppressErrors && isVariableUsage(tok, var.isPointer(), *alloc))
uninitvarError(tok, tok->str(), *alloc);
else
// assume that variable is assigned
return true;
}
else if (Token::Match(tok, "sizeof|typeof|offsetof|decltype ("))
tok = tok->linkAt(1);
else if (tok->str() == "?") {
if (!tok->astOperand2())
return true;
const bool used1 = isVariableUsed(tok->astOperand2()->astOperand1(), var);
const bool used0 = isVariableUsed(tok->astOperand2()->astOperand2(), var);
const bool err = (number_of_if == 0) ? (used1 || used0) : (used1 && used0);
if (err)
uninitvarError(tok, var.nameToken()->str(), *alloc);
return true;
}
tok = tok->next();
}
return bool(noreturn==nullptr);
}
// variable is seen..
if (tok->varId() == var.declarationId()) {
// calling function that returns uninit data through pointer..
if (var.isPointer() &&
Token::Match(tok->next(), "= %name% (") &&
Token::simpleMatch(tok->linkAt(3), ") ;") &&
_settings->library.returnuninitdata.count(tok->strAt(2)) > 0U) {
*alloc = NO_CTOR_CALL;
continue;
}
if (var.isPointer() && (var.typeStartToken()->isStandardType() || (var.type() && var.type()->needInitialization == Type::True)) && Token::simpleMatch(tok->next(), "= new")) {
*alloc = CTOR_CALL;
if (var.typeScope() && var.typeScope()->numConstructors > 0)
return true;
continue;
}
if (!membervar.empty()) {
if (isMemberVariableAssignment(tok, membervar)) {
checkRhs(tok, var, *alloc, number_of_if, membervar);
return true;
}
if (isMemberVariableUsage(tok, var.isPointer(), *alloc, membervar))
uninitStructMemberError(tok, tok->str() + "." + membervar);
else if (Token::Match(tok->previous(), "[(,] %name% [,)]"))
return true;
} else {
// Use variable
if (!suppressErrors && isVariableUsage(tok, var.isPointer(), *alloc))
uninitvarError(tok, tok->str(), *alloc);
else {
if (tok->strAt(1) == "=")
checkRhs(tok, var, *alloc, number_of_if, "");
// assume that variable is assigned
return true;
}
}
}
}
return false;
}
bool CheckUninitVar::checkIfForWhileHead(const Token *startparentheses, const Variable& var, bool suppressErrors, bool isuninit, Alloc alloc, const std::string &membervar)
{
const Token * const endpar = startparentheses->link();
if (Token::Match(startparentheses, "( ! %name% %oror%") && startparentheses->tokAt(2)->getValue(0))
suppressErrors = true;
for (const Token *tok = startparentheses->next(); tok && tok != endpar; tok = tok->next()) {
if (tok->varId() == var.declarationId()) {
if (Token::Match(tok, "%name% . %name%")) {
if (tok->strAt(2) == membervar) {
if (isMemberVariableAssignment(tok, membervar))
return true;
if (!suppressErrors && isMemberVariableUsage(tok, var.isPointer(), alloc, membervar))
uninitStructMemberError(tok, tok->str() + "." + membervar);
}
continue;
}
if (isVariableUsage(tok, var.isPointer(), alloc)) {
if (suppressErrors)
continue;
uninitvarError(tok, tok->str(), alloc);
}
return true;
}
if (Token::Match(tok, "sizeof|decltype|offsetof ("))
tok = tok->next()->link();
if ((!isuninit || !membervar.empty()) && tok->str() == "&&")
suppressErrors = true;
}
return false;
}
bool CheckUninitVar::checkLoopBody(const Token *tok, const Variable& var, const Alloc alloc, const std::string &membervar, const bool suppressErrors)
{
const Token *usetok = nullptr;
assert(tok->str() == "{");
for (const Token * const end = tok->link(); tok != end; tok = tok->next()) {
if (tok->varId() == var.declarationId()) {
if (!membervar.empty()) {
if (isMemberVariableAssignment(tok, membervar)) {
bool assign = true;
bool rhs = false;
for (const Token *tok2 = tok->next(); tok2; tok2 = tok2->next()) {
if (tok2->str() == "=")
rhs = true;
if (tok2->str() == ";")
break;
if (rhs && tok2->varId() == var.declarationId() && isMemberVariableUsage(tok2, var.isPointer(), alloc, membervar)) {
assign = false;
break;
}
}
if (assign)
return true;
}
if (Token::Match(tok, "%name% ="))
return true;
if (isMemberVariableUsage(tok, var.isPointer(), alloc, membervar))
usetok = tok;
else if (Token::Match(tok->previous(), "[(,] %name% [,)]"))
return true;
} else {
if (isVariableUsage(tok, var.isPointer(), alloc))
usetok = tok;
else if (tok->strAt(1) == "=") {
// Is var used in rhs?
bool rhs = false;
std::stack<const Token *> tokens;
tokens.push(tok->next()->astOperand2());
while (!tokens.empty()) {
const Token *t = tokens.top();
tokens.pop();
if (!t)
continue;
if (t->varId() == var.declarationId()) {
// var is used in rhs
rhs = true;
break;
}
if (Token::simpleMatch(t->previous(),"sizeof ("))
continue;
tokens.push(t->astOperand1());
tokens.push(t->astOperand2());
}
if (!rhs)
return true;
} else {
return true;
}
}
}
if (Token::Match(tok, "sizeof|typeof ("))
tok = tok->next()->link();
if (Token::Match(tok, "asm ( %str% ) ;"))
return true;
}
if (!suppressErrors && usetok) {
if (membervar.empty())
uninitvarError(usetok, usetok->str(), alloc);
else
uninitStructMemberError(usetok, usetok->str() + "." + membervar);
return true;
}
return false;
}
void CheckUninitVar::checkRhs(const Token *tok, const Variable &var, Alloc alloc, unsigned int number_of_if, const std::string &membervar)
{
bool rhs = false;
unsigned int indent = 0;
while (nullptr != (tok = tok->next())) {
if (tok->str() == "=")
rhs = true;
else if (rhs && tok->varId() == var.declarationId()) {
if (membervar.empty() && isVariableUsage(tok, var.isPointer(), alloc))
uninitvarError(tok, tok->str(), alloc);
else if (!membervar.empty() && isMemberVariableUsage(tok, var.isPointer(), alloc, membervar))
uninitStructMemberError(tok, tok->str() + "." + membervar);
} else if (tok->str() == ";" || (indent==0 && tok->str() == ","))
break;
else if (tok->str() == "(")
++indent;
else if (tok->str() == ")") {
if (indent == 0)
break;
--indent;
} else if (tok->str() == "?" && tok->astOperand2()) {
const bool used1 = isVariableUsed(tok->astOperand2()->astOperand1(), var);
const bool used0 = isVariableUsed(tok->astOperand2()->astOperand2(), var);
const bool err = (number_of_if == 0) ? (used1 || used0) : (used1 && used0);
if (err)
uninitvarError(tok, var.nameToken()->str(), alloc);
break;
} else if (Token::simpleMatch(tok, "sizeof ("))
tok = tok->next()->link();
}
}
bool CheckUninitVar::isVariableUsage(const Token *vartok, bool pointer, Alloc alloc) const
{
if (alloc == NO_ALLOC && ((Token::Match(vartok->previous(), "return|delete") && vartok->strAt(1) != "=") || (vartok->strAt(-1) == "]" && vartok->linkAt(-1)->strAt(-1) == "delete")))
return true;
// Passing variable to typeof/__alignof__
if (Token::Match(vartok->tokAt(-3), "typeof|__alignof__ ( * %name%"))
return false;
// Accessing Rvalue member using "." or "->"
if (vartok->strAt(1) == "." && vartok->strAt(-1) != "&") {
// Is struct member passed to function?
if (!pointer && Token::Match(vartok->previous(), "[,(] %name% . %name%")) {
// TODO: there are FN currently:
// - should only return false if struct member is (or might be) array.
// - should only return false if function argument is (or might be) non-const pointer or reference
const Token *tok2 = vartok->next();
do {
tok2 = tok2->tokAt(2);
} while (Token::Match(tok2, ". %name%"));
if (Token::Match(tok2, "[,)]"))
return false;
} else if (pointer && alloc != CTOR_CALL && Token::Match(vartok, "%name% . %name% (")) {
return true;
}
bool assignment = false;
const Token* parent = vartok->astParent();
while (parent) {
if (parent->str() == "=") {
assignment = true;
break;
}
if (alloc != NO_ALLOC && parent->str() == "(") {
if (_settings->library.functionpure.find(parent->strAt(-1)) == _settings->library.functionpure.end()) {
assignment = true;
break;
}
}
parent = parent->astParent();
}
if (!assignment)
return true;
}
// Passing variable to function..
if (Token::Match(vartok->previous(), "[(,] %name% [,)]") || Token::Match(vartok->tokAt(-2), "[(,] & %name% [,)]")) {
const int use = isFunctionParUsage(vartok, pointer, alloc);
if (use >= 0)
return (use>0);
}
if (Token::Match(vartok->previous(), "++|--|%cop%")) {
if (_tokenizer->isCPP() && Token::Match(vartok->previous(), ">>|<<")) {
const Token* tok2 = vartok->previous();
if (Token::simpleMatch(tok2->astOperand1(), ">>"))
return false; // Looks like stream operator, initializes the variable
if (Token::simpleMatch(tok2, "<<")) {
// Looks like stream operator, but could also initialize the variable. Check lhs.
do {
tok2 = tok2->astOperand1();
} while (Token::simpleMatch(tok2, "<<"));
if (tok2 && tok2->strAt(-1) == "::")
tok2 = tok2->previous();
if (tok2 && (Token::simpleMatch(tok2->previous(), "std ::") || (tok2->variable() && tok2->variable()->isStlType()) || tok2->isStandardType()))
return true;
}
const Variable *var = vartok->tokAt(-2)->variable();
return (var && var->typeStartToken()->isStandardType());
}
// is there something like: ; "*((&var ..expr.. =" => the variable is assigned
if (vartok->previous()->str() == "&" && !vartok->previous()->astOperand2())
return false;
// bailout to avoid fp for 'int x = 2 + x();' where 'x()' is a unseen preprocessor macro (seen in linux)
if (!pointer && vartok->next() && vartok->next()->str() == "(")
return false;
if (vartok->previous()->str() != "&" || !Token::Match(vartok->tokAt(-2), "[(,=?:]")) {
if (alloc != NO_ALLOC && vartok->previous()->str() == "*") {
const Token *parent = vartok->previous()->astParent();
if (parent && parent->str() == "=" && parent->astOperand1() == vartok->previous())
return false;
return true;
}
return alloc == NO_ALLOC;
}
}
if (alloc == NO_ALLOC && Token::Match(vartok->previous(), "= %name% ;|%cop%"))
return true;
bool unknown = false;
if (pointer && CheckNullPointer::isPointerDeRef(vartok, unknown)) {
// pointer is allocated - dereferencing it is ok.
if (alloc != NO_ALLOC)
return false;
// function parameter?
bool functionParameter = false;
if (Token::Match(vartok->tokAt(-2), "%name% (") || vartok->previous()->str() == ",")
functionParameter = true;
// if this is not a function parameter report this dereference as variable usage
if (!functionParameter)
return true;
}
if (_tokenizer->isCPP() && Token::Match(vartok->next(), "<<|>>")) {
// Is this calculation done in rhs?
const Token *tok = vartok;
while (tok && Token::Match(tok, "%name%|.|::"))
tok = tok->previous();
if (Token::Match(tok, "[;{}]"))
return false;
// Is variable a known POD type then this is a variable usage,
// otherwise we assume it's not.
const Variable *var = vartok->variable();
return (var && var->typeStartToken()->isStandardType());
}
if (alloc == NO_ALLOC && vartok->next() && vartok->next()->isOp() && !vartok->next()->isAssignmentOp())
return true;
if (vartok->strAt(1) == "]")
return true;
return false;
}
/***
* Is function parameter "used" so a "usage of uninitialized variable" can
* be written? If parameter is passed "by value" then it is "used". If it
* is passed "by reference" then it is not necessarily "used".
* @return -1 => unknown 0 => not used 1 => used
*/
int CheckUninitVar::isFunctionParUsage(const Token *vartok, bool pointer, Alloc alloc) const
{
if (!Token::Match(vartok->previous(), "[(,]") && !Token::Match(vartok->tokAt(-2), "[(,] &"))
return -1;
// locate start parentheses in function call..
unsigned int argumentNumber = 0;
const Token *start = vartok;
while (start && !Token::Match(start, "[;{}(]")) {
if (start->str() == ")")
start = start->link();
else if (start->str() == ",")
++argumentNumber;
start = start->previous();
}
// is this a function call?
if (start && Token::Match(start->previous(), "%name% (")) {
const bool address(vartok->previous()->str() == "&");
const bool array(vartok->variable() && vartok->variable()->isArray());
// check how function handle uninitialized data arguments..
const Function *func = start->previous()->function();
if (func) {
const Variable *arg = func->getArgumentVar(argumentNumber);
if (arg) {
const Token *argStart = arg->typeStartToken();
if (!address && !array && Token::Match(argStart, "struct| %type% %name%| [,)]"))
return 1;
if (pointer && !address && alloc == NO_ALLOC && Token::Match(argStart, "struct| %type% * %name% [,)]"))
return 1;
while (argStart->previous() && argStart->previous()->isName())
argStart = argStart->previous();
if (Token::Match(argStart, "const %type% & %name% [,)]"))
return 1;
if ((pointer || address) && alloc == NO_ALLOC && Token::Match(argStart, "const struct| %type% * %name% [,)]"))
return 1;
if ((pointer || address) && Token::Match(argStart, "const %type% %name% [") && Token::Match(argStart->linkAt(3), "] [,)]"))
return 1;
}
} else if (Token::Match(start->previous(), "if|while|for")) {
// control-flow statement reading the variable "by value"
return alloc == NO_ALLOC;
} else {
const bool isnullbad = _settings->library.isnullargbad(start->previous(), argumentNumber + 1);
if (pointer && !address && isnullbad && alloc == NO_ALLOC)
return true;
const bool isuninitbad = _settings->library.isuninitargbad(start->previous(), argumentNumber + 1);
if (alloc != NO_ALLOC)
return isnullbad && isuninitbad;
return isuninitbad && (!address || isnullbad);
}
}
// unknown
return -1;
}
bool CheckUninitVar::isMemberVariableAssignment(const Token *tok, const std::string &membervar) const
{
if (Token::Match(tok, "%name% . %name%") && tok->strAt(2) == membervar) {
if (Token::Match(tok->tokAt(3), "[=.[]"))
return true;
else if (Token::Match(tok->tokAt(-2), "[(,=] &"))
return true;
else if (Token::Match(tok->tokAt(-2), "%name% >>") && Token::Match(tok->tokAt(3), ";|>>")) // #6680
return true;
else if ((tok->previous() && tok->previous()->isConstOp()) || Token::Match(tok->previous(), "[|="))
; // member variable usage
else if (tok->tokAt(3)->isConstOp())
; // member variable usage
else if (Token::Match(tok->previous(), "[(,] %name% . %name% [,)]") &&
1 == isFunctionParUsage(tok, false, NO_ALLOC)) {
return false;
} else
return true;
} else if (tok->strAt(1) == "=")
return true;
else if (tok->strAt(-1) == "&") {
if (Token::Match(tok->tokAt(-2), "[(,] & %name%")) {
// locate start parentheses in function call..
unsigned int argumentNumber = 0;
const Token *ftok = tok;
while (ftok && !Token::Match(ftok, "[;{}(]")) {
if (ftok->str() == ")")
ftok = ftok->link();
else if (ftok->str() == ",")
++argumentNumber;
ftok = ftok->previous();
}
// is this a function call?
ftok = ftok ? ftok->previous() : NULL;
if (Token::Match(ftok, "%name% (")) {
// check how function handle uninitialized data arguments..
const Function *function = ftok->function();
const Variable *arg = function ? function->getArgumentVar(argumentNumber) : NULL;
const Token *argStart = arg ? arg->typeStartToken() : NULL;
while (argStart && argStart->previous() && argStart->previous()->isName())
argStart = argStart->previous();
if (Token::Match(argStart, "const struct| %type% * const| %name% [,)]"))
return false;
}
else if (ftok && Token::simpleMatch(ftok->previous(), "= * ("))
return false;
}
return true;
}
return false;
}
bool CheckUninitVar::isMemberVariableUsage(const Token *tok, bool isPointer, Alloc alloc, const std::string &membervar) const
{
if (Token::Match(tok->previous(), "[(,] %name% . %name% [,)]") &&
tok->strAt(2) == membervar) {
int use = isFunctionParUsage(tok, isPointer, alloc);
if (use == 1)
return true;
}
if (isMemberVariableAssignment(tok, membervar))
return false;
if (Token::Match(tok, "%name% . %name%") && tok->strAt(2) == membervar && !(tok->tokAt(-2)->variable() && tok->tokAt(-2)->variable()->isReference()))
return true;
else if (!isPointer && Token::Match(tok->previous(), "[(,] %name% [,)]") && isVariableUsage(tok, isPointer, alloc))
return true;
else if (!isPointer && Token::Match(tok->previous(), "= %name% ;"))
return true;
// = *(&var);
else if (!isPointer &&
Token::simpleMatch(tok->astParent(),"&") &&
Token::simpleMatch(tok->astParent()->astParent(),"*") &&
Token::Match(tok->astParent()->astParent()->astParent(), "= * (| &") &&
tok->astParent()->astParent()->astParent()->astOperand2() == tok->astParent()->astParent())
return true;
else if (_settings->experimental &&
!isPointer &&
Token::Match(tok->tokAt(-2), "[(,] & %name% [,)]") &&
isVariableUsage(tok, isPointer, alloc))
return true;
return false;
}
void CheckUninitVar::uninitstringError(const Token *tok, const std::string &varname, bool strncpy_)
{
reportError(tok, Severity::error, "uninitstring", "Dangerous usage of '" + varname + "'" + (strncpy_ ? " (strncpy doesn't always null-terminate it)." : " (not null-terminated)."));
}
void CheckUninitVar::uninitdataError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::error, "uninitdata", "Memory is allocated but not initialized: " + varname);
}
void CheckUninitVar::uninitvarError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::error, "uninitvar", "Uninitialized variable: " + varname);
}
void CheckUninitVar::uninitStructMemberError(const Token *tok, const std::string &membername)
{
reportError(tok,
Severity::error,
"uninitStructMember",
"Uninitialized struct member: " + membername);
}
void CheckUninitVar::deadPointer()
{
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
std::list<Scope>::const_iterator scope;
// check every executable scope
for (scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) {
if (!scope->isExecutable())
continue;
// Dead pointers..
for (const Token* tok = scope->classStart; tok != scope->classEnd; tok = tok->next()) {
if (tok->variable() &&
tok->variable()->isPointer() &&
isVariableUsage(tok, true, NO_ALLOC)) {
const Token *alias = tok->getValueTokenDeadPointer();
if (alias) {
deadPointerError(tok,alias);
}
}
}
}
}
void CheckUninitVar::deadPointerError(const Token *pointer, const Token *alias)
{
const std::string strpointer(pointer ? pointer->str() : std::string("pointer"));
const std::string stralias(alias ? alias->expressionString() : std::string("&x"));
reportError(pointer,
Severity::error,
"deadpointer",
"Dead pointer usage. Pointer '" + strpointer + "' is dead if it has been assigned '" + stralias + "' at line " + MathLib::toString(alias ? alias->linenr() : 0U) + ".");
}
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