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::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 (membervar.empty())
return true;
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;
}
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 (tok->varId() != var.declarationId())
return false;
if (!var.isArray())
return true;
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);
}
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;
}
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, VariableValue> variableValue;
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()] = !VariableValue(0);
// Inner scope..
else if (Token::simpleMatch(tok, "if (")) {
bool alwaysTrue = false;
bool alwaysFalse = false;
conditionAlwaysTrueOrFalse(tok->next()->astOperand2(), 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;
VariableValue condVarValue(0);
const Token *condVarTok = nullptr;
if (alwaysFalse)
;
else if (Token::simpleMatch(tok, "if (") &&
astIsVariableComparison(tok->next()->astOperand2(), "!=", "0", &condVarTok)) {
std::map<unsigned int,VariableValue>::const_iterator it = variableValue.find(condVarTok->varId());
if (it != variableValue.end() && it->second != 0)
return true; // this scope is not fully analysed => return true
else {
condVarId = condVarTok->varId();
condVarValue = !VariableValue(0);
}
} else if (Token::simpleMatch(tok, "if (") && Token::Match(tok->next()->astOperand2(), "==|!=")) {
const Token *condition = tok->next()->astOperand2();
const Token *lhs = condition->astOperand1();
const Token *rhs = condition->astOperand2();
const Token *vartok = rhs && rhs->isNumber() ? lhs : rhs;
const Token *numtok = rhs && rhs->isNumber() ? rhs : lhs;
while (Token::simpleMatch(vartok, "."))
vartok = vartok->astOperand2();
if (vartok && vartok->varId() && numtok) {
std::map<unsigned int,VariableValue>::const_iterator it = variableValue.find(vartok->varId());
if (it != variableValue.end() && it->second != MathLib::toLongNumber(numtok->str()))
return true; // this scope is not fully analysed => return true
else {
condVarId = vartok->varId();
condVarValue = VariableValue(MathLib::toLongNumber(numtok->str()));
if (condition->str() == "!=")
condVarValue = !condVarValue;
}
}
}
// goto the {
tok = tok->next()->link()->next();
if (!tok)
break;
if (tok->str() == "{") {
bool possibleInitIf((!alwaysTrue && 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 && (initif || noreturnIf))
return true;
std::map<unsigned int, VariableValue> 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()] = !VariableValue(0);
else if (Token::Match(tok2, "[;{}.] %name% = %num% ;"))
varValueIf[tok2->next()->varId()] = VariableValue(MathLib::toLongNumber(tok2->strAt(3)));
}
}
if (initif && condVarId > 0U)
variableValue[condVarId] = !condVarValue;
// 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((!alwaysFalse && number_of_if > 0) || suppressErrors);
bool noreturnElse = false;
const bool initelse = !alwaysTrue && checkScopeForVariable(tok->next(), var, &possibleInitElse, &noreturnElse, alloc, membervar);
std::map<unsigned int, VariableValue> 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()] = !VariableValue(0);
else if (Token::Match(tok2, "[;{}.] %var% = %num% ;"))
varValueElse[tok2->next()->varId()] = VariableValue(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 (var.isPointer() || var.isArray()) {
if (Token::findmatch(tok->tokAt(2), "%varid%", end, var.declarationId()))
return true;
} else 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;
}
// bailout if there is a goto label
if (Token::Match(tok, "[;{}] %name% :")) {
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;
tok = tok->next();
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.typeStartToken()->isEnumType() || (var.type() && var.type()->needInitialization == Type::True)) && Token::simpleMatch(tok->next(), "= new")) {
*alloc = CTOR_CALL;
// type has constructor(s)
if (var.typeScope() && var.typeScope()->numConstructors > 0)
return true;
// standard or enum type: check if new initializes the allocated memory
if (var.typeStartToken()->isStandardType() || var.typeStartToken()->isEnumType()) {
// scalar new with initialization
if (Token::Match(tok->next(), "= new %type% ("))
return true;
// array new
if (Token::Match(tok->next(), "= new %type% [")) {
const Token* tokClosingBracket=tok->linkAt(4);
// array new with initialization
if (tokClosingBracket && Token::simpleMatch(tokClosingBracket->next(), "( )"))
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;
}
