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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2010 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 <sstream>
#include <iostream>
#include <string>
//---------------------------------------------------------------------------
// Register this check class into cppcheck by creating a static instance of it..
namespace
{
static CheckAutoVariables instance;
}
// _callStack used when parsing into subfunctions.
bool CheckAutoVariables::errorAv(const Token* left, const Token* right)
{
if (fp_list.find(left->str()) == fp_list.end())
{
return false;
}
return isAutoVar(right->varId());
}
bool CheckAutoVariables::isAutoVar(unsigned int varId)
{
if (varId == 0)
{
return false;
}
return (vd_list.find(varId) != vd_list.end());
}
bool CheckAutoVariables::isAutoVarArray(unsigned int varId)
{
if (varId == 0)
{
return false;
}
return (vda_list.find(varId) != vda_list.end());
}
void print(const Token *tok, int num)
{
const Token *t = tok;
std::cout << tok->linenr() << " PRINT ";
for (int i = 0; i < num; i++)
{
std::cout << " [" << t->str() << "] ";
t = t->next();
}
std::cout << std::endl;
}
bool isTypeName(const Token *tok)
{
bool ret = false;
const std::string _str(tok->str());
static const char * const type[] = {"case", "return", "delete", 0};
for (int i = 0; type[i]; i++)
{
ret |= (_str == type[i]);
}
return !ret;
}
bool isExternOrStatic(const Token *tok)
{
bool res = false;
if (Token::Match(tok->tokAt(-1), "extern|static"))
{
res = true;
}
else if (Token::Match(tok->tokAt(-2), "extern|static"))
{
res = true;
}
else if (Token::Match(tok->tokAt(-3), "extern|static"))
{
res = true;
}
//std::cout << __PRETTY_FUNCTION__ << " " << tok->str() << " " << res << std::endl;
return res;
}
void CheckAutoVariables::addVD(unsigned int varId)
{
if (varId > 0)
{
vd_list.insert(varId);
}
}
void CheckAutoVariables::addVDA(unsigned int varId)
{
if (varId > 0)
{
vda_list.insert(varId);
}
}
void CheckAutoVariables::autoVariables()
{
bool begin_function = false;
bool begin_function_decl = false;
int bindent = 0;
// Which variables have an unknown type?
std::set<unsigned int> unknown_type;
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
{
if (Token::Match(tok, "%type% *|::| %var% ("))
{
begin_function = true;
fp_list.clear();
vd_list.clear();
vda_list.clear();
}
else if (begin_function && begin_function_decl && Token::Match(tok, "%type% * * %var%"))
{
fp_list.insert(tok->tokAt(3)->str());
}
else if (begin_function && begin_function_decl && Token::Match(tok, "%type% * %var% ["))
{
fp_list.insert(tok->tokAt(2)->str());
}
else if (begin_function && tok->str() == "(")
{
begin_function_decl = true;
}
else if (begin_function && tok->str() == ")")
{
begin_function_decl = false;
}
else if (begin_function && tok->str() == "{")
{
bindent++;
}
else if (begin_function && tok->str() == "}")
{
bindent--;
}
else if (bindent <= 0)
{
continue;
}
// Inside a function body
if (Token::Match(tok, "%type% :: %any%") && !isExternOrStatic(tok))
{
addVD(tok->tokAt(2)->varId());
}
else if (Token::Match(tok, "%type% %var% ["))
{
addVDA(tok->next()->varId());
}
else if (Token::Match(tok, "%var% %var% ;") && !isExternOrStatic(tok) && isTypeName(tok))
{
addVD(tok->next()->varId());
if (!tok->isStandardType() &&
NULL == Token::findmatch(_tokenizer->tokens(), ("struct|class " + tok->str()).c_str()))
{
unknown_type.insert(tok->next()->varId());
}
}
else if (Token::Match(tok, "const %var% %var% ;") && !isExternOrStatic(tok) && isTypeName(tok->next()))
{
addVD(tok->tokAt(2)->varId());
}
//Critical assignment
else if (Token::Match(tok, "[;{}] %var% = & %var%") && errorAv(tok->tokAt(1), tok->tokAt(4)))
{
errorAutoVariableAssignment(tok);
}
else if (Token::Match(tok, "[;{}] * %var% = & %var%") && errorAv(tok->tokAt(2), tok->tokAt(5)) &&
unknown_type.find(tok->tokAt(5)->varId()) == unknown_type.end())
{
errorAutoVariableAssignment(tok);
}
else if (Token::Match(tok, "[;{}] %var% [ %any% ] = & %var%") && errorAv(tok->tokAt(1), tok->tokAt(7)))
{
errorAutoVariableAssignment(tok);
}
// Critical return
else if (Token::Match(tok, "return & %var% ;") && isAutoVar(tok->tokAt(2)->varId()))
{
reportError(tok, Severity::error, "autoVariables", "Return of the address of an auto-variable");
}
// Invalid pointer deallocation
else if (Token::Match(tok, "free ( %var% ) ;") && isAutoVarArray(tok->tokAt(2)->varId()))
{
reportError(tok, Severity::error, "autoVariables", "Invalid deallocation");
}
}
vd_list.clear();
vda_list.clear();
fp_list.clear();
}
//---------------------------------------------------------------------------
void CheckAutoVariables::returnPointerToLocalArray()
{
bool infunc = false;
int indentlevel = 0;
std::set<unsigned int> arrayVar;
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
{
// Is there a function declaration for a function that returns a pointer?
if (!infunc && (Token::Match(tok, "%type% * %var% (") || Token::Match(tok, "%type% * %var% :: %var% (")))
{
for (const Token *tok2 = tok; tok2; tok2 = tok2->next())
{
if (tok2->str() == ")")
{
tok = tok2;
break;
}
}
if (Token::simpleMatch(tok, ") {"))
{
infunc = true;
indentlevel = 0;
arrayVar.clear();
}
}
// Parsing a function that returns a pointer..
if (infunc)
{
if (tok->str() == "{")
{
++indentlevel;
}
else if (tok->str() == "}")
{
--indentlevel;
if (indentlevel <= 0)
{
infunc = false;
}
continue;
}
// Declaring a local array..
if (Token::Match(tok, "[;{}] %type% %var% ["))
{
const unsigned int varid = tok->tokAt(2)->varId();
if (varid > 0)
{
arrayVar.insert(varid);
}
}
// Return pointer to local array variable..
if (Token::Match(tok, "return %var% ;"))
{
const unsigned int varid = tok->next()->varId();
if (varid > 0 && arrayVar.find(varid) != arrayVar.end())
{
errorReturnPointerToLocalArray(tok);
}
}
}
// Declaring array variable..
}
}
void CheckAutoVariables::errorReturnPointerToLocalArray(const Token *tok)
{
reportError(tok, Severity::error, "returnLocalVariable", "Returning pointer to local array variable");
}
void CheckAutoVariables::errorAutoVariableAssignment(const Token *tok)
{
reportError(tok, Severity::error, "autoVariables",
"Assigning address of local auto-variable to a function parameter.\n"
"Dangerous assignment - function parameter takes the address of a local "
"auto-variable. Local auto-variables are reserved from the stack. And the "
"stack is freed when the function ends. So the pointer to a local variable "
"is invalid after the function ends.");
}
// return temporary?
bool CheckAutoVariables::returnTemporary(const Token *tok) const
{
if (!Token::Match(tok, "return %var% ("))
return false;
return bool(0 != Token::findmatch(_tokenizer->tokens(), ("std :: string " + tok->next()->str() + " (").c_str()));
}
void CheckAutoVariables::returnReference()
{
// locate function that returns a reference..
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
{
// Skip executable scopes..
if (Token::Match(tok, ") const| {"))
{
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
tok = tok->link();
continue;
}
// have we reached a function that returns a reference?
if (Token::Match(tok, "%type% & %var% (") ||
Token::Match(tok, "> & %var% ("))
{
// go to the '('
const Token *tok2 = tok->tokAt(3);
// go to the ')'
tok2 = tok2->link();
// is this a function implementation?
if (Token::Match(tok2, ") const| {"))
{
unsigned int indentlevel = 0;
std::set<unsigned int> localvar; // local variables in function
while (0 != (tok2 = tok2->next()))
{
// indentlevel..
if (tok2->str() == "{")
++indentlevel;
else if (tok2->str() == "}")
{
if (indentlevel <= 1)
break;
--indentlevel;
}
// declare local variable..
if (Token::Match(tok2, "[{};] %type%") && tok2->next()->str() != "return")
{
// goto next token..
tok2 = tok2->next();
// skip "const"
if (Token::Match(tok2, "const %type%"))
tok2 = tok2->next();
// skip "std::" if it is seen
if (Token::simpleMatch(tok2, "std ::"))
tok2 = tok2->tokAt(2);
// is it a variable declaration?
if (Token::Match(tok2, "%type% %var% ;"))
localvar.insert(tok2->next()->varId());
else if (Token::Match(tok2, "%type% < %any% > %var% ;"))
localvar.insert(tok2->tokAt(4)->varId());
}
// return..
else if (Token::Match(tok2, "return %var% ;"))
{
// is the returned variable a local variable?
if ((tok2->next()->varId() > 0) &&
(localvar.find(tok2->next()->varId()) != localvar.end()))
{
// 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", "Returning reference to auto variable");
}
void CheckAutoVariables::errorReturnTempReference(const Token *tok)
{
reportError(tok, Severity::error, "returnTempReference", "Returning reference to temporary");
}
// Return c_str
void CheckAutoVariables::returncstr()
{
// locate function that returns a const char *..
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
{
// Skip executable scopes..
if (Token::Match(tok, ") const| {"))
{
tok = tok->next();
if (tok->str() == "const")
tok = tok->next();
tok = tok->link();
continue;
}
// have we reached a function that returns a reference?
if (Token::Match(tok, "const char *"))
{
// go to the '('
const Token *tok2 = tok->tokAt(3);
while (Token::Match(tok2, "%var% ::"))
tok2 = tok2->tokAt(2);
if (!Token::Match(tok2, "%var% ("))
continue;
// go to the ')'
tok2 = tok2->next()->link();
// is this a function implementation?
if (Token::Match(tok2, ") const| {"))
{
unsigned int indentlevel = 0;
std::set<unsigned int> localvar; // local variables in function
while (0 != (tok2 = tok2->next()))
{
// indentlevel..
if (tok2->str() == "{")
++indentlevel;
else if (tok2->str() == "}")
{
if (indentlevel <= 1)
break;
--indentlevel;
}
// declare local variable..
if (Token::Match(tok2, "[{};] %type%") && tok2->next()->str() != "return")
{
// goto next token..
tok2 = tok2->next();
// skip "const"
if (Token::Match(tok2, "const %type%"))
tok2 = tok2->next();
// skip "std::" if it is seen
if (Token::simpleMatch(tok2, "std ::"))
tok2 = tok2->tokAt(2);
// is it a variable declaration?
if (Token::Match(tok2, "%type% %var% [;=]"))
localvar.insert(tok2->next()->varId());
}
// return..
else if (Token::Match(tok2, "return %var% . c_str ( ) ;"))
{
// is the returned variable a local variable?
if ((tok2->next()->varId() > 0) &&
(localvar.find(tok2->next()->varId()) != localvar.end()))
{
// report error..
errorReturnAutocstr(tok2);
}
}
// return pointer to temporary..
else if (returnTemporary(tok2))
{
// report error..
errorReturnTempPointer(tok2);
}
}
}
}
}
}
void CheckAutoVariables::errorReturnAutocstr(const Token *tok)
{
reportError(tok, Severity::error, "returnAutocstr", "Returning pointer to auto variable");
}
void CheckAutoVariables::errorReturnTempPointer(const Token *tok)
{
reportError(tok, Severity::error, "returnTempPointer", "Returning pointer to temporary");
}
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