347 lines
15 KiB
C++
347 lines
15 KiB
C++
/*
|
|
* Cppcheck - A tool for static C/C++ code analysis
|
|
* Copyright (C) 2007-2012 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/>.
|
|
*/
|
|
|
|
//---------------------------------------------------------------------------
|
|
// Auto variables checks
|
|
//---------------------------------------------------------------------------
|
|
|
|
#include "checkautovariables.h"
|
|
#include "symboldatabase.h"
|
|
|
|
#include <list>
|
|
#include <string>
|
|
|
|
//---------------------------------------------------------------------------
|
|
|
|
|
|
// Register this check class into cppcheck by creating a static instance of it..
|
|
namespace {
|
|
static CheckAutoVariables instance;
|
|
}
|
|
|
|
|
|
bool CheckAutoVariables::isRefPtrArg(unsigned int varId)
|
|
{
|
|
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(varId);
|
|
|
|
return(var && var->isArgument() && var->isReference() && var->isPointer());
|
|
}
|
|
|
|
bool CheckAutoVariables::isPtrArg(unsigned int varId)
|
|
{
|
|
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(varId);
|
|
|
|
return(var && var->isArgument() && var->isPointer());
|
|
}
|
|
|
|
bool CheckAutoVariables::isAutoVar(unsigned int varId)
|
|
{
|
|
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(varId);
|
|
|
|
if (!var || !var->isLocal() || var->isStatic())
|
|
return false;
|
|
|
|
if (var->isReference()) {
|
|
// address of reference variable can be taken if the address
|
|
// of the variable it points at is not a auto-var
|
|
// TODO: check what the reference variable references.
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool CheckAutoVariables::isAutoVarArray(unsigned int varId)
|
|
{
|
|
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(varId);
|
|
|
|
return (var && var->isLocal() && !var->isStatic() && var->isArray());
|
|
}
|
|
|
|
// Verification that we really take the address of a local variable
|
|
static bool checkRvalueExpression(const Variable* var, const Token* next)
|
|
{
|
|
return((next->str() != "." || (!var->isPointer() && (!var->isClass() || var->type()))) && next->strAt(2) != ".");
|
|
}
|
|
|
|
void CheckAutoVariables::autoVariables()
|
|
{
|
|
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
|
|
|
|
std::list<Scope>::const_iterator scope;
|
|
|
|
for (scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) {
|
|
// only check functions
|
|
if (scope->type != Scope::eFunction)
|
|
continue;
|
|
|
|
for (const Token *tok = scope->classStart; tok && tok != scope->classEnd; tok = tok->next()) {
|
|
// Critical assignment
|
|
if (Token::Match(tok, "[;{}] %var% = & %var%") && isRefPtrArg(tok->next()->varId()) && isAutoVar(tok->tokAt(4)->varId())) {
|
|
const Variable * var = symbolDatabase->getVariableFromVarId(tok->tokAt(4)->varId());
|
|
if (checkRvalueExpression(var, tok->tokAt(5)))
|
|
errorAutoVariableAssignment(tok->next(), false);
|
|
} else if (Token::Match(tok, "[;{}] * %var% = & %var%") && isPtrArg(tok->tokAt(2)->varId()) && isAutoVar(tok->tokAt(5)->varId())) {
|
|
const Variable * var = symbolDatabase->getVariableFromVarId(tok->tokAt(5)->varId());
|
|
if (checkRvalueExpression(var, tok->tokAt(6)))
|
|
errorAutoVariableAssignment(tok->next(), false);
|
|
} else if (Token::Match(tok, "[;{}] %var% . %var% = & %var%")) {
|
|
// TODO: check if the parameter is only changed temporarily (#2969)
|
|
if (_settings->inconclusive) {
|
|
const Variable * var1 = symbolDatabase->getVariableFromVarId(tok->next()->varId());
|
|
if (var1 && var1->isArgument() && var1->isPointer()) {
|
|
const Variable * var2 = symbolDatabase->getVariableFromVarId(tok->tokAt(6)->varId());
|
|
if (isAutoVar(tok->tokAt(6)->varId()) && checkRvalueExpression(var2, tok->tokAt(7)))
|
|
errorAutoVariableAssignment(tok->next(), true);
|
|
}
|
|
}
|
|
tok = tok->tokAt(6);
|
|
} else if (Token::Match(tok, "[;{}] %var% . %var% = %var% ;")) {
|
|
// TODO: check if the parameter is only changed temporarily (#2969)
|
|
if (_settings->inconclusive) {
|
|
const Variable * var1 = symbolDatabase->getVariableFromVarId(tok->next()->varId());
|
|
if (var1 && var1->isArgument() && var1->isPointer()) {
|
|
if (isAutoVarArray(tok->tokAt(5)->varId()))
|
|
errorAutoVariableAssignment(tok->next(), true);
|
|
}
|
|
}
|
|
tok = tok->tokAt(5);
|
|
} else if (Token::Match(tok, "[;{}] * %var% = %var% ;")) {
|
|
const Variable * var1 = symbolDatabase->getVariableFromVarId(tok->tokAt(2)->varId());
|
|
if (var1 && var1->isArgument() && Token::Match(var1->nameToken()->tokAt(-3), "%type% * *")) {
|
|
if (isAutoVarArray(tok->tokAt(4)->varId()))
|
|
errorAutoVariableAssignment(tok->next(), false);
|
|
}
|
|
tok = tok->tokAt(4);
|
|
} else if (Token::Match(tok, "[;{}] %var% [") && Token::Match(tok->linkAt(2), "] = & %var%") && isPtrArg(tok->next()->varId()) && isAutoVar(tok->linkAt(2)->tokAt(3)->varId())) {
|
|
const Token* const varTok = tok->linkAt(2)->tokAt(3);
|
|
const Variable * var = symbolDatabase->getVariableFromVarId(varTok->varId());
|
|
if (checkRvalueExpression(var, varTok->next()))
|
|
errorAutoVariableAssignment(tok->next(), false);
|
|
}
|
|
// Critical return
|
|
else if (Token::Match(tok, "return & %var% ;") && isAutoVar(tok->tokAt(2)->varId())) {
|
|
errorReturnAddressToAutoVariable(tok);
|
|
} else if (Token::Match(tok, "return & %var% [") &&
|
|
Token::simpleMatch(tok->linkAt(3), "] ;") &&
|
|
isAutoVarArray(tok->tokAt(2)->varId())) {
|
|
errorReturnAddressToAutoVariable(tok);
|
|
} else if (Token::Match(tok, "return & %var% ;") && tok->tokAt(2)->varId()) {
|
|
const Variable * var1 = symbolDatabase->getVariableFromVarId(tok->tokAt(2)->varId());
|
|
if (var1 && var1->isArgument() && var1->typeEndToken()->str() != "&")
|
|
errorReturnAddressOfFunctionParameter(tok, tok->strAt(2));
|
|
}
|
|
// Invalid pointer deallocation
|
|
else if (Token::Match(tok, "free ( %var% ) ;") || Token::Match(tok, "delete [| ]| (| %var% !![")) {
|
|
tok = Token::findmatch(tok->next(), "%var%");
|
|
if (isAutoVarArray(tok->varId()))
|
|
errorInvalidDeallocation(tok);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
|
|
void CheckAutoVariables::returnPointerToLocalArray()
|
|
{
|
|
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
|
|
|
|
std::list<Scope>::const_iterator scope;
|
|
|
|
for (scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) {
|
|
// only check functions
|
|
if (scope->type != Scope::eFunction || !scope->function)
|
|
continue;
|
|
|
|
const Token *tok = scope->function->tokenDef;
|
|
|
|
// have we reached a function that returns a pointer
|
|
if (tok->previous() && tok->previous()->str() == "*") {
|
|
for (const Token *tok2 = scope->classStart; tok2 && tok2 != scope->classEnd; tok2 = tok2->next()) {
|
|
// Return pointer to local array variable..
|
|
if (Token::Match(tok2, "return %var% ;")) {
|
|
const unsigned int varid = tok2->next()->varId();
|
|
if (isAutoVarArray(varid)) {
|
|
errorReturnPointerToLocalArray(tok2);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckAutoVariables::errorReturnAddressToAutoVariable(const Token *tok)
|
|
{
|
|
reportError(tok, Severity::error, "returnAddressOfAutoVariable", "Address of an auto-variable returned.");
|
|
}
|
|
|
|
void CheckAutoVariables::errorReturnPointerToLocalArray(const Token *tok)
|
|
{
|
|
reportError(tok, Severity::error, "returnLocalVariable", "Pointer to local array variable returned.");
|
|
}
|
|
|
|
void CheckAutoVariables::errorAutoVariableAssignment(const Token *tok, bool inconclusive)
|
|
{
|
|
if (!inconclusive) {
|
|
reportError(tok, Severity::error, "autoVariables",
|
|
"Address of local auto-variable assigned to a function parameter.\n"
|
|
"Dangerous assignment - the function parameter is assigned the address of a local "
|
|
"auto-variable. Local auto-variables are reserved from the stack which "
|
|
"is freed when the function ends. So the pointer to a local variable "
|
|
"is invalid after the function ends.");
|
|
} else {
|
|
reportError(tok, Severity::error, "autoVariables",
|
|
"Address of local auto-variable assigned to a function parameter.\n"
|
|
"Function parameter is assigned the address of a local auto-variable. "
|
|
"Local auto-variables are reserved from the stack which is freed when "
|
|
"the function ends. The address is invalid after the function ends and it "
|
|
"might 'leak' from the function through the parameter.", true);
|
|
}
|
|
}
|
|
|
|
void CheckAutoVariables::errorReturnAddressOfFunctionParameter(const Token *tok, const std::string &varname)
|
|
{
|
|
reportError(tok, Severity::error, "returnAddressOfFunctionParameter",
|
|
"Address of function parameter '" + varname + "' returned.\n"
|
|
"Address of the function parameter '" + varname + "' becomes invalid after the function exits because "
|
|
"function parameters are stored on the stack which is freed when the function exits. Thus the returned "
|
|
"value is invalid.");
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
|
|
// return temporary?
|
|
bool CheckAutoVariables::returnTemporary(const Token *tok) const
|
|
{
|
|
if (!Token::Match(tok, "return %var% ("))
|
|
return false;
|
|
// TODO: Find all functions that return objects by value
|
|
return bool(NULL != Token::findmatch(_tokenizer->tokens(), ("std :: string " + tok->next()->str() + " (").c_str()));
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
|
|
void CheckAutoVariables::returnReference()
|
|
{
|
|
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
|
|
|
|
std::list<Scope>::const_iterator scope;
|
|
|
|
for (scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) {
|
|
// only check functions
|
|
if (scope->type != Scope::eFunction || !scope->function)
|
|
continue;
|
|
|
|
const Token *tok = scope->function->tokenDef;
|
|
|
|
// have we reached a function that returns a reference?
|
|
if (tok->previous() && tok->previous()->str() == "&") {
|
|
for (const Token *tok2 = scope->classStart; tok2 && tok2 != scope->classEnd; tok2 = tok2->next()) {
|
|
// return..
|
|
if (Token::Match(tok2, "return %var% ;")) {
|
|
// is the returned variable a local variable?
|
|
const unsigned int varid1 = tok2->next()->varId();
|
|
const Variable *var1 = symbolDatabase->getVariableFromVarId(varid1);
|
|
|
|
if (isAutoVar(varid1)) {
|
|
// If reference variable is used, check what it references
|
|
if (Token::Match(var1->nameToken(), "%var% [=(]")) {
|
|
const Token *tok3 = var1->nameToken()->tokAt(2);
|
|
if (!Token::Match(tok3, "%var% [);.]"))
|
|
continue;
|
|
|
|
// Only report error if variable that is referenced is
|
|
// a auto variable
|
|
if (!isAutoVar(tok3->varId()))
|
|
continue;
|
|
}
|
|
|
|
// report error..
|
|
errorReturnReference(tok2);
|
|
}
|
|
}
|
|
|
|
// return reference to temporary..
|
|
else if (returnTemporary(tok2)) {
|
|
// report error..
|
|
errorReturnTempReference(tok2);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckAutoVariables::errorReturnReference(const Token *tok)
|
|
{
|
|
reportError(tok, Severity::error, "returnReference", "Reference to auto variable returned.");
|
|
}
|
|
|
|
void CheckAutoVariables::errorReturnTempReference(const Token *tok)
|
|
{
|
|
reportError(tok, Severity::error, "returnTempReference", "Reference to temporary returned.");
|
|
}
|
|
|
|
void CheckAutoVariables::errorInvalidDeallocation(const Token *tok)
|
|
{
|
|
reportError(tok,
|
|
Severity::error,
|
|
"autovarInvalidDeallocation",
|
|
"Deallocation of an auto-variable results in undefined behaviour.\n"
|
|
"The deallocation of an auto-variable results in undefined behaviour. You should only free memory "
|
|
"that has been allocated dynamically.");
|
|
}
|
|
|
|
|
|
//---------------------------------------------------------------------------
|
|
|
|
// Return c_str
|
|
void CheckAutoVariables::returncstr()
|
|
{
|
|
// TODO: Move this to CheckStl::string_c_str
|
|
|
|
// locate function that returns a const char *..
|
|
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
|
|
|
|
std::list<Scope>::const_iterator scope;
|
|
|
|
for (scope = symbolDatabase->scopeList.begin(); scope != symbolDatabase->scopeList.end(); ++scope) {
|
|
// only check functions
|
|
if (scope->type != Scope::eFunction || !scope->function)
|
|
continue;
|
|
|
|
const Token *tok = scope->function->tokenDef;
|
|
|
|
// have we reached a function that returns a const char *
|
|
if (Token::simpleMatch(tok->tokAt(-3), "const char *")) {
|
|
for (const Token *tok2 = scope->classStart; tok2 && tok2 != scope->classEnd; tok2 = tok2->next()) {
|
|
// return pointer to temporary..
|
|
if (returnTemporary(tok2)) {
|
|
// report error..
|
|
errorReturnTempPointer(tok2);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckAutoVariables::errorReturnTempPointer(const Token *tok)
|
|
{
|
|
reportError(tok, Severity::error, "returnTempPointer", "Pointer to temporary returned.");
|
|
}
|