cppcheck/lib/astutils.cpp

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/*
* Cppcheck - A tool for static C/C++ code analysis
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* Copyright (C) 2007-2016 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 "astutils.h"
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#include "library.h"
#include "mathlib.h"
#include "settings.h"
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#include "symboldatabase.h"
#include "token.h"
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#include "valueflow.h"
#include <list>
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static bool astIsCharWithSign(const Token *tok, ValueType::Sign sign)
{
if (!tok)
return false;
const ValueType *valueType = tok->valueType();
if (!valueType)
return false;
return valueType->type == ValueType::Type::CHAR && valueType->pointer == 0U && valueType->sign == sign;
}
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bool astIsSignedChar(const Token *tok)
{
return astIsCharWithSign(tok, ValueType::Sign::SIGNED);
}
bool astIsUnknownSignChar(const Token *tok)
{
return astIsCharWithSign(tok, ValueType::Sign::UNKNOWN_SIGN);
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}
bool astIsIntegral(const Token *tok, bool unknown)
{
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const ValueType *vt = tok ? tok->valueType() : nullptr;
if (!vt)
return unknown;
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return vt->isIntegral() && vt->pointer == 0U;
}
bool astIsFloat(const Token *tok, bool unknown)
{
const ValueType *vt = tok ? tok->valueType() : nullptr;
if (!vt)
return unknown;
return vt->type >= ValueType::Type::FLOAT && vt->pointer == 0U;
}
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bool astIsBool(const Token *tok)
{
return tok && (tok->isBoolean() || (tok->valueType() && tok->valueType()->type == ValueType::Type::BOOL && !tok->valueType()->pointer));
}
std::string astCanonicalType(const Token *expr)
{
if (!expr)
return "";
if (expr->variable()) {
const Variable *var = expr->variable();
std::string ret;
for (const Token *type = var->typeStartToken(); Token::Match(type,"%name%|::") && type != var->nameToken(); type = type->next()) {
if (!Token::Match(type, "const|static"))
ret += type->str();
}
return ret;
}
// TODO: handle expressions
return "";
}
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static bool match(const Token *tok, const std::string &rhs)
{
if (tok->str() == rhs)
return true;
if (tok->isName() && !tok->varId() && tok->values().size() == 1U && tok->values().front().isKnown() && MathLib::toString(tok->values().front().intvalue) == rhs)
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return true;
return false;
}
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const Token * astIsVariableComparison(const Token *tok, const std::string &comp, const std::string &rhs, const Token **vartok)
{
if (!tok)
return nullptr;
const Token *ret = nullptr;
if (tok->isComparisonOp()) {
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if (tok->astOperand1() && match(tok->astOperand1(), rhs)) {
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// Invert comparator
std::string s = tok->str();
if (s[0] == '>')
s[0] = '<';
else if (s[0] == '<')
s[0] = '>';
if (s == comp) {
ret = tok->astOperand2();
}
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} else if (tok->str() == comp && tok->astOperand2() && match(tok->astOperand2(), rhs)) {
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ret = tok->astOperand1();
}
} else if (comp == "!=" && rhs == std::string("0")) {
ret = tok;
} else if (comp == "==" && rhs == std::string("0")) {
if (tok->str() == "!")
ret = tok->astOperand1();
}
while (ret && ret->str() == ".")
ret = ret->astOperand2();
if (ret && ret->varId() == 0U)
ret = nullptr;
if (vartok)
*vartok = ret;
return ret;
}
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bool isSameExpression(bool cpp, bool macro, const Token *tok1, const Token *tok2, const Library& library, bool pure)
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{
if (tok1 == nullptr && tok2 == nullptr)
return true;
if (tok1 == nullptr || tok2 == nullptr)
return false;
if (cpp) {
if (tok1->str() == "." && tok1->astOperand1() && tok1->astOperand1()->str() == "this")
tok1 = tok1->astOperand2();
if (tok2->str() == "." && tok2->astOperand1() && tok2->astOperand1()->str() == "this")
tok2 = tok2->astOperand2();
}
if (tok1->varId() != tok2->varId() || tok1->str() != tok2->str() || tok1->originalName() != tok2->originalName()) {
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if ((Token::Match(tok1,"<|>") && Token::Match(tok2,"<|>")) ||
(Token::Match(tok1,"<=|>=") && Token::Match(tok2,"<=|>="))) {
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return isSameExpression(cpp, macro, tok1->astOperand1(), tok2->astOperand2(), library, pure) &&
isSameExpression(cpp, macro, tok1->astOperand2(), tok2->astOperand1(), library, pure);
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}
return false;
}
if (macro && (tok1->isExpandedMacro() || tok2->isExpandedMacro()))
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return false;
if (tok1->isComplex() != tok2->isComplex())
return false;
if (tok1->isLong() != tok2->isLong())
return false;
if (tok1->isUnsigned() != tok2->isUnsigned())
return false;
if (tok1->isSigned() != tok2->isSigned())
return false;
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if (tok1->isName() && tok1->next()->str() == "(" && tok1->str() != "sizeof") {
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if (!tok1->function() && !Token::Match(tok1->previous(), ".|::") && pure && !library.isFunctionConst(tok1->str(), true) && !tok1->isAttributeConst() && !tok1->isAttributePure())
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return false;
else if (tok1->function() && !tok1->function()->isConst() && !tok1->function()->isAttributeConst() && !tok1->function()->isAttributePure())
return false;
}
// templates/casts
if ((Token::Match(tok1, "%name% <") && tok1->next()->link()) ||
(Token::Match(tok2, "%name% <") && tok2->next()->link())) {
// non-const template function that is not a dynamic_cast => return false
if (Token::simpleMatch(tok1->next()->link(), "> (") &&
!(tok1->function() && tok1->function()->isConst()) &&
tok1->str() != "dynamic_cast")
return false;
// some template/cast stuff.. check that the template arguments are same
const Token *t1 = tok1->next();
const Token *t2 = tok2->next();
const Token *end1 = t1->link();
const Token *end2 = t2->link();
while (t1 && t2 && t1 != end1 && t2 != end2) {
if (t1->str() != t2->str())
return false;
t1 = t1->next();
t2 = t2->next();
}
if (t1 != end1 || t2 != end2)
return false;
}
if (tok1->tokType() == Token::eIncDecOp || tok1->isAssignmentOp())
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return false;
// bailout when we see ({..})
if (tok1->str() == "{")
return false;
if (tok1->str() == "(" && tok1->previous() && !tok1->previous()->isName()) { // cast => assert that the casts are equal
const Token *t1 = tok1->next();
const Token *t2 = tok2->next();
while (t1 && t2 &&
t1->str() == t2->str() &&
t1->isLong() == t2->isLong() &&
t1->isUnsigned() == t2->isUnsigned() &&
t1->isSigned() == t2->isSigned() &&
(t1->isName() || t1->str() == "*")) {
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t1 = t1->next();
t2 = t2->next();
}
if (!t1 || !t2 || t1->str() != ")" || t2->str() != ")")
return false;
}
bool noncommutativeEquals =
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isSameExpression(cpp, macro, tok1->astOperand1(), tok2->astOperand1(), library, pure);
noncommutativeEquals = noncommutativeEquals &&
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isSameExpression(cpp, macro, tok1->astOperand2(), tok2->astOperand2(), library, pure);
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if (noncommutativeEquals)
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return true;
// in c++, a+b might be different to b+a, depending on the type of a and b
if (cpp && tok1->str() == "+") {
const ValueType* vt1 = tok1->astOperand1()->valueType();
const ValueType* vt2 = tok1->astOperand1()->valueType();
if (!(vt1 && (vt1->type >= ValueType::VOID || vt1->pointer) && vt2 && (vt2->type >= ValueType::VOID || vt2->pointer)))
return false;
}
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const bool commutative = tok1->astOperand1() && tok1->astOperand2() && Token::Match(tok1, "%or%|%oror%|+|*|&|&&|^|==|!=");
bool commutativeEquals = commutative &&
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isSameExpression(cpp, macro, tok1->astOperand2(), tok2->astOperand1(), library, pure);
commutativeEquals = commutativeEquals &&
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isSameExpression(cpp, macro, tok1->astOperand1(), tok2->astOperand2(), library, pure);
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return commutativeEquals;
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}
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bool isOppositeCond(bool isNot, bool cpp, const Token * const cond1, const Token * const cond2, const Library& library, bool pure)
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{
if (!cond1 || !cond2)
return false;
if (cond1->str() == "!") {
if (cond2->str() == "!=") {
if (cond2->astOperand1() && cond2->astOperand1()->str() == "0")
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return isSameExpression(cpp, true, cond1->astOperand1(), cond2->astOperand2(), library, pure);
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if (cond2->astOperand2() && cond2->astOperand2()->str() == "0")
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return isSameExpression(cpp, true, cond1->astOperand1(), cond2->astOperand1(), library, pure);
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}
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return isSameExpression(cpp, true, cond1->astOperand1(), cond2, library, pure);
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}
if (cond2->str() == "!")
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return isOppositeCond(isNot, cpp, cond2, cond1, library, pure);
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if (!cond1->isComparisonOp() || !cond2->isComparisonOp())
return false;
const std::string &comp1 = cond1->str();
// condition found .. get comparator
std::string comp2;
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if (isSameExpression(cpp, true, cond1->astOperand1(), cond2->astOperand1(), library, pure) &&
isSameExpression(cpp, true, cond1->astOperand2(), cond2->astOperand2(), library, pure)) {
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comp2 = cond2->str();
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} else if (isSameExpression(cpp, true, cond1->astOperand1(), cond2->astOperand2(), library, pure) &&
isSameExpression(cpp, true, cond1->astOperand2(), cond2->astOperand1(), library, pure)) {
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comp2 = cond2->str();
if (comp2[0] == '>')
comp2[0] = '<';
else if (comp2[0] == '<')
comp2[0] = '>';
}
// is condition opposite?
return ((comp1 == "==" && comp2 == "!=") ||
(comp1 == "!=" && comp2 == "==") ||
(comp1 == "<" && comp2 == ">=") ||
(comp1 == "<=" && comp2 == ">") ||
(comp1 == ">" && comp2 == "<=") ||
(comp1 == ">=" && comp2 == "<") ||
(!isNot && ((comp1 == "<" && comp2 == ">") ||
(comp1 == ">" && comp2 == "<"))));
}
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bool isConstExpression(const Token *tok, const Library& library, bool pure)
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{
if (!tok)
return true;
if (tok->isName() && tok->next()->str() == "(") {
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if (!tok->function() && !Token::Match(tok->previous(), ".|::") && !library.isFunctionConst(tok->str(), pure))
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return false;
else if (tok->function() && !tok->function()->isConst())
return false;
}
if (tok->tokType() == Token::eIncDecOp)
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return false;
// bailout when we see ({..})
if (tok->str() == "{")
return false;
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return isConstExpression(tok->astOperand1(), library, pure) && isConstExpression(tok->astOperand2(), library, pure);
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}
bool isWithoutSideEffects(bool cpp, const Token* tok)
{
if (!cpp)
return true;
while (tok && tok->astOperand2() && tok->astOperand2()->str() != "(")
tok = tok->astOperand2();
if (tok && tok->varId()) {
const Variable* var = tok->variable();
return var && (!var->isClass() || var->isPointer() || var->isStlType());
}
return true;
}
bool isReturnScope(const Token * const endToken)
{
if (!endToken || endToken->str() != "}")
return false;
const Token *prev = endToken->previous();
while (prev && Token::simpleMatch(prev->previous(), "; ;"))
prev = prev->previous();
if (prev && Token::simpleMatch(prev->previous(), "} ;"))
prev = prev->previous();
if (Token::simpleMatch(prev, "}")) {
if (Token::simpleMatch(prev->link()->tokAt(-2), "} else {"))
return isReturnScope(prev) && isReturnScope(prev->link()->tokAt(-2));
if (Token::simpleMatch(prev->link()->previous(), ") {") &&
Token::simpleMatch(prev->link()->linkAt(-1)->previous(), "switch (") &&
!Token::findsimplematch(prev->link(), "break", prev)) {
return true;
}
if (Token::simpleMatch(prev->link()->previous(), ") {") &&
Token::simpleMatch(prev->link()->linkAt(-1)->previous(), "return (")) {
return true;
}
if (Token::Match(prev->link()->previous(), "[;{}] {"))
return isReturnScope(prev);
} else if (Token::simpleMatch(prev, ";")) {
// noreturn function
if (Token::simpleMatch(prev->previous(), ") ;") && Token::Match(prev->linkAt(-1)->tokAt(-2), "[;{}] %name% ("))
return true;
// return/goto statement
prev = prev->previous();
while (prev && !Token::Match(prev, ";|{|}|return|goto|throw|continue|break"))
prev = prev->previous();
return prev && prev->isName();
}
return false;
}
bool isVariableChangedByFunctionCall(const Token *tok, const Settings *settings, bool *inconclusive)
{
if (!tok)
return false;
// address of variable
const bool addressOf = tok && Token::simpleMatch(tok->previous(), "&");
// passing variable to subfunction?
if (Token::Match(tok->tokAt(-2), ") & %name% [,)]") && Token::Match(tok->linkAt(-2)->previous(), "[,(] ("))
;
else if (Token::Match(tok->tokAt(addressOf?-2:-1), "[(,] &| %name% [,)]"))
;
else
return false;
// reinterpret_cast etc..
if (Token::Match(tok->tokAt(-3), "> ( & %name% ) [,)]") &&
tok->linkAt(-3) &&
Token::Match(tok->linkAt(-3)->tokAt(-2), "[,(] %type% <"))
tok = tok->linkAt(-3);
// 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() : nullptr;
if (tok && tok->link() && tok->str() == ">")
tok = tok->link()->previous();
if (!Token::Match(tok, "%name% ("))
return false; // not a function => variable not changed
if (tok->varId())
return false; // Constructor call of tok => variable probably not changed by constructor call
if (!tok->function()) {
// if the library says 0 is invalid
// => it is assumed that parameter is an in parameter (TODO: this is a bad heuristic)
if (!addressOf && settings->library.isnullargbad(tok, 1+argnr))
return false;
// addressOf => inconclusive
if (!addressOf) {
if (inconclusive != nullptr)
*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();
}
bool isVariableChanged(const Token *start, const Token *end, const unsigned int varid, const Settings *settings)
{
for (const Token *tok = start; tok != end; tok = tok->next()) {
if (tok->varId() == varid) {
if (Token::Match(tok, "%name% %assign%|++|--"))
return true;
if (Token::Match(tok->previous(), "++|-- %name%"))
return true;
const Token *ftok = tok;
while (ftok && !Token::Match(ftok, "[({[]"))
ftok = ftok->astParent();
if (ftok && Token::Match(ftok->link(), ") !!{")) {
bool inconclusive = false;
bool isChanged = isVariableChangedByFunctionCall(tok, settings, &inconclusive);
isChanged |= inconclusive;
if (isChanged)
return true;
}
const Token *parent = tok->astParent();
while (Token::Match(parent, ".|::"))
parent = parent->astParent();
if (parent && parent->tokType() == Token::eIncDecOp)
return true;
}
}
return false;
}
int numberOfArguments(const Token *start)
{
int arguments=0;
const Token* const openBracket = start->next();
if (openBracket && openBracket->str()=="(" && openBracket->next() && openBracket->next()->str()!=")") {
const Token* argument=openBracket->next();
while (argument) {
++arguments;
argument = argument->nextArgument();
}
}
return arguments;
}
static void getArgumentsRecursive(const Token *tok, std::vector<const Token *> *arguments)
{
if (!tok)
return;
if (tok->str() == ",") {
getArgumentsRecursive(tok->astOperand1(), arguments);
getArgumentsRecursive(tok->astOperand2(), arguments);
} else {
arguments->push_back(tok);
}
}
std::vector<const Token *> getArguments(const Token *ftok)
{
std::vector<const Token *> arguments;
getArgumentsRecursive(ftok->next()->astOperand2(), &arguments);
return arguments;
}