/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2013 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 .
*/
#include "valueflow.h"
#include "errorlogger.h"
#include "mathlib.h"
#include "settings.h"
#include "symboldatabase.h"
#include "token.h"
#include "tokenlist.h"
#include
#include
static void printvalues(const Token *tok)
{
if (tok->values.empty())
std::cout << "empty";
for (std::list::const_iterator it = tok->values.begin(); it != tok->values.end(); ++it)
std::cout << " " << (it->intvalue);
std::cout << std::endl;
}
static void bailout(TokenList *tokenlist, ErrorLogger *errorLogger, const Token *tok, const std::string &what)
{
std::list callstack;
callstack.push_back(ErrorLogger::ErrorMessage::FileLocation(tok,tokenlist));
ErrorLogger::ErrorMessage errmsg(callstack, Severity::debug, "ValueFlow bailout: " + what, "valueFlowBailout", false);
errorLogger->reportErr(errmsg);
}
static bool bailoutFunctionPar(const Token *tok, const ValueFlow::Value &value, const Settings *settings, bool *inconclusive)
{
// passing variable to subfunction?
const bool addressOf = tok && Token::Match(tok->previous(), "&");
if (!tok || !Token::Match(tok->tokAt(addressOf?-2:-1), "[(,] &| %var% [,)]"))
return false;
// goto start of function call and get argnr
unsigned int argnr = 0;
while (tok && tok->str() != "(") {
if (tok->str() == ",")
++argnr;
else if (tok->str() == ")")
tok = tok->link();
tok = tok->previous();
}
tok = tok ? tok->previous() : NULL;
if (!Token::Match(tok,"%var% ("))
return false; // not a function => dont bailout
if (!tok->function()) {
// if value is 0 and the library says 0 is invalid => dont bailout
if (value.intvalue==0 && settings->library.isnullargbad(tok->str(), 1+argnr))
return false;
// inconclusive => don't bailout
if (inconclusive && !addressOf && settings->inconclusive) {
*inconclusive = true;
return false;
}
return true;
}
const Variable *arg = tok->function()->getArgumentVar(argnr);
if (addressOf && !(arg && arg->isConst()))
return true;
return arg && !arg->isConst() && arg->isReference();
}
/**
* Should value be skipped because it's hidden inside && || or ?: expression.
* Example: ((x!=NULL) && (*x == 123))
* If 'valuetok' points at the x in '(*x == 123)'. Then the '&&' will be returned.
* @param valuetok original variable token
* @return NULL=>don't skip, non-NULL=>The operator token that cause the skip. For instance the '&&'.
* */
static const Token * skipValueInConditionalExpression(const Token * const valuetok)
{
// Walk up the ast
const Token *prev = valuetok;
for (const Token *tok = valuetok->astParent(); tok; tok = tok->astParent()) {
const bool prevIsLhs = (prev == tok->astOperand1());
prev = tok;
if (prevIsLhs || !Token::Match(tok, "%oror%|&&|?|:"))
continue;
// Is variable protected in LHS..
std::stack tokens;
tokens.push(tok->astOperand1());
while (!tokens.empty()) {
const Token * const tok2 = tokens.top();
tokens.pop();
if (!tok2)
continue;
if (tok2 != valuetok && tok2->str() == valuetok->str())
return tok;
tokens.push(tok2->astOperand2());
tokens.push(tok2->astOperand1());
}
}
return NULL;
}
static bool bailoutSelfAssignment(const Token * const tok)
{
const Token *parent = tok;
while (parent) {
const Token *op = parent;
parent = parent->astParent();
// Assignment where lhs variable exists in rhs => return true
if (parent != NULL &&
parent->astOperand2() == op &&
parent->astOperand1() != NULL &&
parent->str() == "=") {
for (const Token *lhs = parent->astOperand1(); lhs; lhs = lhs->astOperand1()) {
if (lhs->varId() == tok->varId())
return true;
if (lhs->astOperand2() && lhs->astOperand2()->varId() == tok->varId())
return true;
}
}
}
return false;
}
/** set ValueFlow value and perform calculations if possible */
static void setTokenValue(Token* tok, const ValueFlow::Value &value)
{
// if value already exists, don't add it again
std::list::iterator it;
for (it = tok->values.begin(); it != tok->values.end(); ++it) {
if (it->intvalue == value.intvalue) {
if (it->inconclusive && !value.inconclusive) {
*it = value;
break;
}
return;
}
}
if (it == tok->values.end()) {
tok->values.push_back(value);
it = tok->values.end();
--it;
}
Token *parent = const_cast(tok->astParent());
// Cast..
if (parent && parent->str() == "(" && tok == parent->link()->next()) {
setTokenValue(parent,value);
}
// Calculations..
else if (parent && parent->isArithmeticalOp() && parent->astOperand1() && parent->astOperand2()) {
std::list::const_iterator value1, value2;
for (value1 = parent->astOperand1()->values.begin(); value1 != parent->astOperand1()->values.end(); ++value1) {
for (value2 = parent->astOperand2()->values.begin(); value2 != parent->astOperand2()->values.end(); ++value2) {
if (value1->varId == 0U || value2->varId == 0U ||
(value1->varId == value2->varId && value1->varvalue == value2->varvalue)) {
ValueFlow::Value result(0);
result.condition = value1->condition ? value1->condition : value2->condition;
result.inconclusive = value1->inconclusive | value2->inconclusive;
result.varId = (value1->varId != 0U) ? value1->varId : value2->varId;
result.varvalue = (result.varId == value1->varId) ? value1->intvalue : value2->intvalue;
switch (parent->str()[0]) {
case '+':
result.intvalue = value1->intvalue + value2->intvalue;
setTokenValue(parent, result);
break;
case '-':
result.intvalue = value1->intvalue - value2->intvalue;
setTokenValue(parent, result);
break;
case '*':
result.intvalue = value1->intvalue * value2->intvalue;
setTokenValue(parent, result);
break;
case '/':
if (value2->intvalue == 0)
break;
result.intvalue = value1->intvalue / value2->intvalue;
setTokenValue(parent, result);
break;
case '%':
if (value2->intvalue == 0)
break;
result.intvalue = value1->intvalue % value2->intvalue;
setTokenValue(parent, result);
break;
}
}
}
}
}
}
static void valueFlowNumber(TokenList *tokenlist)
{
for (Token *tok = tokenlist->front(); tok; tok = tok->next()) {
if (tok->isNumber() && MathLib::isInt(tok->str()))
setTokenValue(tok, ValueFlow::Value(MathLib::toLongNumber(tok->str())));
}
}
static void valueFlowBeforeCondition(TokenList *tokenlist, ErrorLogger *errorLogger, const Settings *settings)
{
for (Token *tok = tokenlist->front(); tok; tok = tok->next()) {
unsigned int varid;
MathLib::bigint num;
const Variable *var;
if (tok->isComparisonOp() && tok->astOperand1() && tok->astOperand2()) {
if (tok->astOperand1()->isName() && tok->astOperand2()->isNumber()) {
varid = tok->astOperand1()->varId();
var = tok->astOperand1()->variable();
num = MathLib::toLongNumber(tok->astOperand2()->str());
} else if (tok->astOperand1()->isNumber() && tok->astOperand2()->isName()) {
varid = tok->astOperand2()->varId();
var = tok->astOperand2()->variable();
num = MathLib::toLongNumber(tok->astOperand1()->str());
} else {
continue;
}
} else if (Token::Match(tok->previous(), "if|while ( %var% %oror%|&&|)") ||
Token::Match(tok, "%oror%|&& %var% %oror%|&&|)")) {
varid = tok->next()->varId();
var = tok->next()->variable();
num = 0;
} else if (tok->str() == "!" && tok->astOperand1() && tok->astOperand1()->isName()) {
varid = tok->astOperand1()->varId();
var = tok->astOperand1()->variable();
num = 0;
} else {
continue;
}
if (varid == 0U || !var)
continue;
// bailout: global non-const variables
if (!(var->isLocal() || var->isArgument()) && !var->isConst()) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok, "global variable " + var->nameToken()->str());
continue;
}
// bailout: while-condition, variable is changed in while loop
for (const Token *tok2 = tok; tok2; tok2 = tok2->astParent()) {
if (tok2->astParent() || tok2->str() != "(" || !Token::simpleMatch(tok2->link(), ") {"))
continue;
if (Token::Match(tok2->previous(), "for|while (")) {
const Token *start = tok2->link()->next();
const Token *end = start->link();
if (Token::findmatch(start,"++|--| %varid% ++|--|=",end,varid)) {
varid = 0U;
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok, "variable " + var->nameToken()->str() + " used in loop");
}
}
// if,macro => bailout
else if (Token::simpleMatch(tok2->previous(), "if (") && tok2->previous()->isExpandedMacro()) {
varid = 0U;
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok, "variable " + var->nameToken()->str() + ", condition is defined in macro");
}
}
if (varid == 0U)
continue;
// extra logic for unsigned variables 'i>=1' => possible value can also be 0
ValueFlow::Value val(tok, num);
val.varId = varid;
ValueFlow::Value val2;
if (num==1U && Token::Match(tok,"<=|>=")) {
bool isunsigned = false;
for (const Token* type = var->typeStartToken(); type && type->varId() == 0U; type = type->next())
isunsigned |= type->isUnsigned();
if (isunsigned) {
val2 = ValueFlow::Value(tok,0);
val2.varId = varid;
}
}
if (Token::Match(tok,"<|>")) {
if (num!=0)
continue;
bool isunsigned = false;
for (const Token* type = var->typeStartToken(); type && type->varId() == 0U; type = type->next())
isunsigned |= type->isUnsigned();
if (!isunsigned)
continue;
}
for (Token *tok2 = tok->previous(); ; tok2 = tok2->previous()) {
if (!tok2) {
if (settings->debugwarnings) {
std::list callstack;
callstack.push_back(ErrorLogger::ErrorMessage::FileLocation(tok,tokenlist));
ErrorLogger::ErrorMessage errmsg(callstack, Severity::debug, "iterated too far", "debugValueFlowBeforeCondition", false);
errorLogger->reportErr(errmsg);
}
break;
}
if (tok2->varId() == varid) {
// bailout: assignment
if (Token::Match(tok2->previous(), "!!* %var% =")) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "assignment of " + tok2->str());
break;
}
// increment/decrement
if (Token::Match(tok2->previous(), "[;{}] %var% ++|-- ;"))
val.intvalue += (tok2->strAt(1)=="++") ? -1 : 1;
else if (Token::Match(tok2->tokAt(-2), "[;{}] ++|-- %var% ;"))
val.intvalue += (tok2->strAt(-1)=="++") ? -1 : 1;
else if (Token::Match(tok2->previous(), "++|-- %var%") || Token::Match(tok2, "%var% ++|--")) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "increment/decrement of " + tok2->str());
break;
}
// bailout: variable is used in rhs in assignment to itself
if (bailoutSelfAssignment(tok2)) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "variable " + tok2->str() + " is used in rhs in assignment to itself");
break;
}
// assigned by subfunction?
bool inconclusive = false;
if (bailoutFunctionPar(tok2,val2.condition ? val2 : val, settings, &inconclusive)) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "possible assignment of " + tok2->str() + " by subfunction");
break;
}
val.inconclusive |= inconclusive;
val2.inconclusive |= inconclusive;
// skip if variable is conditionally used in ?: expression
if (const Token *parent = skipValueInConditionalExpression(tok2)) {
if (settings->debugwarnings)
bailout(tokenlist,
errorLogger,
tok2,
"no simplification of " + tok2->str() + " within " + (Token::Match(parent,"[?:]") ? "?:" : parent->str()) + " expression");
continue;
}
setTokenValue(tok2, val);
if (val2.condition)
setTokenValue(tok2,val2);
if (var && tok2 == var->nameToken())
break;
}
// skip sizeof..
if (tok2->str() == ")" && Token::Match(tok2->link()->previous(), "typeof|sizeof ("))
tok2 = tok2->link();
if (tok2->str() == "}") {
if (Token::findmatch(tok2->link(), "%varid%", tok2, varid)) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "variable " + var->nameToken()->str() + " stopping on }");
break;
} else {
tok2 = tok2->link();
}
} else if (tok2->str() == "{") {
// if variable is assigned in loop don't look before the loop
if (tok2->previous() &&
(Token::Match(tok2->previous(), "do") ||
(tok2->strAt(-1) == ")" && Token::Match(tok2->linkAt(-1)->previous(), "for|while (")))) {
const Token *start = tok2;
const Token *end = start->link();
if (Token::findmatch(start,"++|--| %varid% ++|--|=",end,varid)) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "variable " + var->nameToken()->str() + " is assigned in loop. so valueflow analysis bailout when start of loop is reached.");
break;
}
}
// Global variable : stop when leaving the function scope
if (!var->isLocal()) {
if (!Token::Match(tok2->previous(), ")|else|do {"))
break;
if (Token::Match(tok2->previous(), ") {") &&
!Token::Match(tok2->linkAt(-1)->previous(), "if|for|while ("))
break;
}
} else if (tok2->str() == ";") {
const Token *parent = tok2->previous();
while (parent && !Token::Match(parent, "return|break|continue|goto"))
parent = parent->astParent();
// reaching a break/continue/return
if (parent) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "variable " + var->nameToken()->str() + " stopping on " + parent->str());
break;
}
}
// goto label
if (Token::Match(tok2, "[;{}] %var% :")) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "variable " + var->nameToken()->str() + " stopping on goto label");
break;
}
}
}
}
static void valueFlowAfterAssign(TokenList *tokenlist, ErrorLogger *errorLogger, const Settings *settings)
{
// temporarily hide compiler warnings
(void)errorLogger;
(void)settings;
for (Token *tok = tokenlist->front(); tok; tok = tok->next()) {
// Assignment
if ((tok->str() != "=") || (tok->astParent()))
continue;
// Rhs should be a variable
if (!tok->astOperand1() || !tok->astOperand1()->isName())
continue;
unsigned int varid = tok->astOperand1()->varId();
if (varid == 0U)
continue;
const Variable *var = tok->astOperand1()->variable();
if (!var || !var->isLocal())
continue;
const Token * endToken = 0;
for (const Token *tok2 = var->typeStartToken(); tok2; tok2 = tok2->previous()) {
if (tok2->str() == "{") {
endToken = tok2->link();
break;
}
}
// Lhs values..
if (!tok->astOperand2() || tok->astOperand2()->values.empty())
continue;
std::list values = tok->astOperand2()->values;
unsigned int number_of_if = 0;
for (Token *tok2 = tok; tok2 && tok2 != endToken; tok2 = tok2->next()) {
if (Token::Match(tok2, "sizeof|typeof|typeid ("))
tok2 = tok2->linkAt(1);
// conditional block of code that assigns variable..
if (Token::Match(tok2, "%var% (") && Token::Match(tok2->linkAt(1), ") {")) {
Token * const start = tok2->linkAt(1)->next();
Token * const end = start->link();
// TODO: don't check noreturn scopes
if (number_of_if > 0U && Token::findmatch(start, "%varid%", end, varid)) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "variable " + var->nameToken()->str() + " is assigned in conditional code");
break;
}
if (Token::findmatch(start, "++|--| %varid% ++|--|=", end, varid)) {
if (number_of_if == 0 &&
Token::simpleMatch(tok2, "if (") &&
!(Token::simpleMatch(end, "} else {") &&
(Token::findmatch(end, "%varid%", end->linkAt(2), varid) ||
Token::findmatch(end, "return|continue|break", end->linkAt(2))))) {
++number_of_if;
tok2 = end;
} else {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "variable " + var->nameToken()->str() + " is assigned in conditional code");
break;
}
}
}
else if (tok2->str() == "}")
++number_of_if;
if (tok2->varId() == varid) {
// bailout: assignment
if (Token::Match(tok2->previous(), "!!* %var% =")) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "assignment of " + tok2->str());
break;
}
// skip if variable is conditionally used in ?: expression
if (const Token *parent = skipValueInConditionalExpression(tok2)) {
if (settings->debugwarnings)
bailout(tokenlist,
errorLogger,
tok2,
"no simplification of " + tok2->str() + " within " + (Token::Match(parent,"[?:]") ? "?:" : parent->str()) + " expression");
continue;
}
{
std::list::const_iterator it;
for (it = values.begin(); it != values.end(); ++it)
setTokenValue(tok2, *it);
}
// assigned by subfunction?
bool inconclusive = false;
if (bailoutFunctionPar(tok2, ValueFlow::Value(), settings, &inconclusive)) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "possible assignment of " + tok2->str() + " by subfunction");
break;
}
if (inconclusive) {
std::list::iterator it;
for (it = values.begin(); it != values.end(); ++it)
it->inconclusive = true;
}
}
}
}
}
static void valueFlowForLoop(TokenList *tokenlist, ErrorLogger *errorLogger, const Settings *settings)
{
for (Token *tok = tokenlist->front(); tok; tok = tok->next()) {
if (!Token::Match(tok, "for ("))
continue;
tok = tok->tokAt(2);
if (!Token::Match(tok,"%type%| %var% = %num% ;")) { // TODO: don't use %num%
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok, "For loop not handled");
continue;
}
Token * const vartok = tok->tokAt(Token::Match(tok, "%var% =") ? 0 : 1);
const MathLib::bigint num1 = MathLib::toLongNumber(vartok->strAt(2));
if (vartok->varId() == 0U)
continue;
tok = vartok->tokAt(4);
const Token *num2tok = 0;
if (Token::Match(tok, "%varid% <|<=|!=", vartok->varId())) {
tok = tok->next();
num2tok = tok->astOperand2();
if (num2tok && num2tok->str() == "(" && !num2tok->astOperand2())
num2tok = num2tok->astOperand1();
if (!Token::Match(num2tok, "%num%"))
num2tok = 0;
}
if (!num2tok) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok, "For loop not handled");
continue;
}
const MathLib::bigint num2 = MathLib::toLongNumber(num2tok ? num2tok->str() : "0") - ((tok->str()=="<=") ? 0 : 1);
while (tok && tok->str() != ";")
tok = tok->next();
if (!num2tok || !Token::Match(tok, "; %varid% ++ ) {", vartok->varId())) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok, "For loop not handled");
continue;
}
Token * const bodyStart = tok->tokAt(4);
const Token * const bodyEnd = bodyStart->link();
// Is variable modified inside for loop
bool modified = false;
for (const Token *tok2 = bodyStart->next(); tok2 != bodyEnd; tok2 = tok2->next()) {
if (Token::Match(tok2, "%varid% =", vartok->varId())) {
modified = true;
break;
}
}
if (modified)
continue;
for (Token *tok2 = bodyStart->next(); tok2 != bodyEnd; tok2 = tok2->next()) {
if (tok2->varId() == vartok->varId()) {
ValueFlow::Value value1(num1);
value1.varId = tok2->varId();
setTokenValue(tok2, value1);
ValueFlow::Value value2(num2);
value2.varId = tok2->varId();
setTokenValue(tok2, value2);
}
if (tok2->str() == "{") {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "For loop variable " + vartok->str() + " stopping on {");
break;
}
}
}
}
static void valueFlowSubFunction(TokenList *tokenlist, ErrorLogger *errorLogger, const Settings *settings)
{
std::list argvalues;
for (Token *tok = tokenlist->front(); tok; tok = tok->next()) {
if (!Token::Match(tok, "[(,]"))
continue;
// passing value(s) to function
if (Token::Match(tok, "[(,] %var% [,)]") && !tok->next()->values.empty())
argvalues = tok->next()->values;
else if (Token::Match(tok, "[(,] %num% [,)]")) {
argvalues.clear();
argvalues.push_back(ValueFlow::Value(MathLib::toLongNumber(tok->next()->str())));
} else {
// bool operator => values 1/0 are passed to function..
const Token *op = tok->next();
while (op && op->astParent() && !Token::Match(op->astParent(), "[(,]"))
op = op->astParent();
if (Token::Match(op, "%comp%|%oror%|&&|!")) {
argvalues.clear();
argvalues.push_back(ValueFlow::Value(0));
argvalues.push_back(ValueFlow::Value(1));
} else {
// possible values are unknown..
continue;
}
}
const Token * const argumentToken = tok->next();
// is this a function call?
const Token *ftok = tok;
while (ftok && ftok->str() != "(")
ftok = ftok->astParent();
if (!ftok || !ftok->astOperand1() || !ftok->astOperand2() || !ftok->astOperand1()->function())
continue;
// Get argument nr
unsigned int argnr = 0;
for (const Token *argtok = ftok->next(); argtok && argtok != argumentToken; argtok = argtok->nextArgument())
++ argnr;
// Get function argument, and check if parameter is passed by value
const Function * const function = ftok->astOperand1()->function();
const Variable * const arg = function ? function->getArgumentVar(argnr) : NULL;
if (!Token::Match(arg ? arg->typeStartToken() : NULL, "const| %type% %var% ,|)"))
continue;
// Function scope..
const Scope * const functionScope = function ? function->functionScope : NULL;
if (!functionScope)
continue;
// Set value in function scope..
const unsigned int varid2 = arg->nameToken()->varId();
for (const Token *tok2 = functionScope->classStart->next(); tok2 != functionScope->classEnd; tok2 = tok2->next()) {
if (Token::Match(tok2, "%varid% !!=", varid2)) {
std::list &values = const_cast(tok2)->values;
values.insert(values.begin(), argvalues.begin(), argvalues.end());
} else if (tok2->str() == "{") {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "parameter " + arg->nameToken()->str());
break;
}
}
}
}
void ValueFlow::setValues(TokenList *tokenlist, ErrorLogger *errorLogger, const Settings *settings)
{
for (Token *tok = tokenlist->front(); tok; tok = tok->next())
tok->values.clear();
valueFlowNumber(tokenlist);
valueFlowForLoop(tokenlist, errorLogger, settings);
valueFlowBeforeCondition(tokenlist, errorLogger, settings);
valueFlowAfterAssign(tokenlist, errorLogger, settings);
valueFlowSubFunction(tokenlist, errorLogger, settings);
}