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cppcheck/lib/valueflow.cpp

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/*
* 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 <http://www.gnu.org/licenses/>.
*/
#include "valueflow.h"
#include "errorlogger.h"
#include "mathlib.h"
#include "settings.h"
#include "symboldatabase.h"
#include "token.h"
#include "tokenlist.h"
#include <iostream>
static void printvalues(const Token *tok)
{
if (tok->values.empty())
std::cout << "empty";
for (std::list<ValueFlow::Value>::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<ErrorLogger::ErrorMessage::FileLocation> 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)
{
// passing variable to subfunction?
const bool addr = tok && Token::Match(tok->previous(), "&");
if (!tok || !Token::Match(tok->tokAt(addr?-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())
return true; // unknown function bailout
const Variable *arg = tok->function()->getArgumentVar(argnr);
return arg && !arg->isConst() && arg->isReference();
}
static const Token * skipValueInConditionalExpression(const Token *tok)
{
while (tok && !Token::Match(tok, "%oror%|&&|?|:")) {
while (Token::Match(tok->astParent(), "%oror%|&&|?") && tok->astParent()->astOperand1() == tok)
tok = tok->astParent();
tok = tok->astParent();
}
return tok;
}
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)
continue;
// bailout: global non-const variables
if (var && var->isGlobal() && !var->isConst()) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok, "global variable " + var->nameToken()->str());
continue;
}
const ValueFlow::Value val(tok, num);
ValueFlow::Value val2;
if (var && num==1U && Token::Match(tok,"<=|>=")) {
bool isunsigned = var->typeEndToken()->isUnsigned();
for (const Token* type = var->typeStartToken(); type != var->typeEndToken(); type = type->next())
isunsigned |= type->isUnsigned();
if (isunsigned)
val2 = ValueFlow::Value(tok,0);
}
for (Token *tok2 = tok->previous(); ; tok2 = tok2->previous()) {
if (!tok2) {
if (settings->debugwarnings) {
std::list<ErrorLogger::ErrorMessage::FileLocation> 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;
}
// assigned by subfunction?
if (bailoutFunctionPar(tok2)) {
if (settings->debugwarnings)
bailout(tokenlist, errorLogger, tok2, "possible assignment of " + tok2->str() + " by subfunction");
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;
}
tok2->values.push_back(val);
if (val2.condition)
tok2->values.push_back(val2);
if (var && tok2 == var->nameToken())
break;
}
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 (var && var->isGlobal() && tok2->str() == "{") {
if (!Token::Match(tok2->previous(), ")|else {"))
break;
if (Token::Match(tok2->previous(), ") {") &&
!Token::Match(tok2->linkAt(-1)->previous(), "if|for|while ("))
break;
}
}
}
}
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()) {
tok2->values.push_back(ValueFlow::Value(num1));
tok2->values.push_back(ValueFlow::Value(num2));
}
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<ValueFlow::Value> 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<ValueFlow::Value> &values = const_cast<Token*>(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();
valueFlowForLoop(tokenlist, errorLogger, settings);
valueFlowBeforeCondition(tokenlist, errorLogger, settings);
valueFlowSubFunction(tokenlist, errorLogger, settings);
}
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