Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

1352 lines (1149 sloc) 51.51 kB
/*
* 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/>.
*/
//---------------------------------------------------------------------------
#include "checkuninitvar.h"
#include "mathlib.h"
#include "executionpath.h"
#include "checknullpointer.h" // CheckNullPointer::parseFunctionCall
#include "symboldatabase.h"
#include <algorithm>
//---------------------------------------------------------------------------
// Register this check class (by creating a static instance of it)
namespace {
CheckUninitVar instance;
}
//---------------------------------------------------------------------------
// Skip [ .. ]
static const Token * skipBrackets(const Token *tok)
{
while (tok && tok->str() == "[")
tok = tok->link()->next();
return tok;
}
/// @addtogroup Checks
/// @{
/**
* @brief %Check that uninitialized variables aren't used (using ExecutionPath)
* */
class UninitVar : public ExecutionPath {
public:
/** Startup constructor */
explicit UninitVar(Check *c, const SymbolDatabase* db, bool isc)
: ExecutionPath(c, 0), symbolDatabase(db), isC(isc), var(0), alloc(false), strncpy_(false), memset_nonzero(false) {
}
private:
/** Create a copy of this check */
ExecutionPath *copy() {
return new UninitVar(*this);
}
/** no implementation => compiler error if used */
void operator=(const UninitVar &);
/** internal constructor for creating extra checks */
UninitVar(Check *c, const Variable* v, const SymbolDatabase* db, bool isc)
: ExecutionPath(c, v->varId()), symbolDatabase(db), isC(isc), var(v), alloc(false), strncpy_(false), memset_nonzero(false) {
}
/** is other execution path equal? */
bool is_equal(const ExecutionPath *e) const {
const UninitVar *c = static_cast<const UninitVar *>(e);
return (var == c->var && alloc == c->alloc && strncpy_ == c->strncpy_ && memset_nonzero == c->memset_nonzero);
}
/** pointer to symbol database */
const SymbolDatabase* symbolDatabase;
const bool isC;
/** variable for this check */
const Variable* var;
/** is this variable allocated? */
bool alloc;
/** is this variable initialized with strncpy (not always zero-terminated) */
bool strncpy_;
/** is this variable initialized but not zero-terminated (memset) */
bool memset_nonzero;
/** allocating pointer. For example : p = malloc(10); */
static void alloc_pointer(std::list<ExecutionPath *> &checks, unsigned int varid) {
// loop through the checks and perform a allocation if the
// variable id matches
std::list<ExecutionPath *>::const_iterator it;
for (it = checks.begin(); it != checks.end(); ++it) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == varid) {
if (c->var->isPointer() && !c->var->isArray())
c->alloc = true;
else
bailOutVar(checks, varid);
break;
}
}
}
/** Initializing a pointer value. For example: *p = 0; */
static void init_pointer(std::list<ExecutionPath *> &checks, const Token *tok) {
const unsigned int varid(tok->varId());
if (!varid)
return;
// loop through the checks and perform a initialization if the
// variable id matches
std::list<ExecutionPath *>::iterator it = checks.begin();
while (it != checks.end()) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == varid) {
if (c->alloc || c->var->isArray()) {
delete c;
checks.erase(it++);
continue;
} else {
use_pointer(checks, tok);
}
}
++it;
}
}
/** Deallocate a pointer. For example: free(p); */
static void dealloc_pointer(std::list<ExecutionPath *> &checks, const Token *tok) {
const unsigned int varid(tok->varId());
if (!varid)
return;
// loop through the checks and perform a deallocation if the
// variable id matches
std::list<ExecutionPath *>::const_iterator it;
for (it = checks.begin(); it != checks.end(); ++it) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == varid) {
// unallocated pointer variable => error
if (c->var->isPointer() && !c->var->isArray() && !c->alloc) {
CheckUninitVar *checkUninitVar = dynamic_cast<CheckUninitVar *>(c->owner);
if (checkUninitVar) {
checkUninitVar->uninitvarError(tok, c->var->name());
break;
}
}
c->alloc = false;
}
}
}
/**
* Pointer assignment: p = x;
* if p is a pointer and x is an array/pointer then bail out
* \param checks all available checks
* \param tok1 the "p" token
* \param tok2 the "x" token
*/
static void pointer_assignment(std::list<ExecutionPath *> &checks, const Token *tok1, const Token *tok2) {
// Variable id for "left hand side" variable
const unsigned int varid1(tok1->varId());
if (varid1 == 0)
return;
// Variable id for "right hand side" variable
const unsigned int varid2(tok2->varId());
if (varid2 == 0)
return;
std::list<ExecutionPath *>::const_iterator it;
// bail out if first variable is a pointer
for (it = checks.begin(); it != checks.end(); ++it) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == varid1 && c->var->isPointer() && !c->var->isArray()) {
bailOutVar(checks, varid1);
break;
}
}
// bail out if second variable is a array/pointer
for (it = checks.begin(); it != checks.end(); ++it) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == varid2 && (c->var->isPointer() || c->var->isArray())) {
bailOutVar(checks, varid2);
break;
}
}
}
/** Initialize an array with strncpy. */
static void init_strncpy(std::list<ExecutionPath *> &checks, const Token *tok) {
const unsigned int varid(tok->varId());
if (!varid)
return;
std::list<ExecutionPath *>::const_iterator it;
for (it = checks.begin(); it != checks.end(); ++it) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == varid) {
c->strncpy_ = true;
}
}
}
/** Initialize an array with memset (not zero). */
static void init_memset_nonzero(std::list<ExecutionPath *> &checks, const Token *tok) {
const unsigned int varid(tok->varId());
if (!varid)
return;
std::list<ExecutionPath *>::const_iterator it;
for (it = checks.begin(); it != checks.end(); ++it) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == varid) {
c->memset_nonzero = true;
}
}
}
/**
* use - called from the use* functions below.
* @param checks all available checks
* @param tok variable token
* @param mode specific behaviour
* @return if error is found, true is returned
*/
static bool use(std::list<ExecutionPath *> &checks, const Token *tok, const int mode) {
const unsigned int varid(tok->varId());
if (varid == 0)
return false;
std::list<ExecutionPath *>::const_iterator it;
for (it = checks.begin(); it != checks.end(); ++it) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == varid) {
// mode 0 : the variable is used "directly"
// example: .. = var;
// it is ok to read the address of an uninitialized array.
// it is ok to read the address of an allocated pointer
if (mode == 0 && (c->var->isArray() || (c->var->isPointer() && c->alloc)))
continue;
// mode 2 : reading array data with mem.. function. It's ok if the
// array is not 0-terminated
if (mode == 2 && c->strncpy_)
continue;
// mode 3 : bad usage of pointer. if it's not a pointer then the usage is ok.
// example: ptr->foo();
if (mode == 3 && (!c->var->isPointer() || c->var->isArray()))
continue;
// mode 4 : using dead pointer is invalid.
if (mode == 4 && (!c->var->isPointer() || c->var->isArray() || c->alloc))
continue;
// mode 5 : reading uninitialized array or pointer is invalid.
if (mode == 5 && (!c->var->isArray() && !c->var->isPointer()))
continue;
CheckUninitVar *checkUninitVar = dynamic_cast<CheckUninitVar *>(c->owner);
if (checkUninitVar) {
if (c->strncpy_ || c->memset_nonzero)
checkUninitVar->uninitstringError(tok, c->var->name(), c->strncpy_);
else if (c->var->isPointer() && !c->var->isArray() && c->alloc)
checkUninitVar->uninitdataError(tok, c->var->name());
else
checkUninitVar->uninitvarError(tok, c->var->name());
return true;
}
}
}
// No error found
return false;
}
/**
* Reading variable. Use this function in situations when it is
* invalid to read the data of the variable but not the address.
* @param checks all available checks
* @param tok variable token
* @return if error is found, true is returned
*/
static bool use(std::list<ExecutionPath *> &checks, const Token *tok) {
return use(checks, tok, 0);
}
/**
* Reading array elements. If the variable is not an array then the usage is ok.
* @param checks all available checks
* @param tok variable token
*/
static void use_array(std::list<ExecutionPath *> &checks, const Token *tok) {
use(checks, tok, 1);
}
/**
* Reading array elements with a "mem.." function. It's ok if the array is not 0-terminated.
* @param checks all available checks
* @param tok variable token
*/
static void use_array_mem(std::list<ExecutionPath *> &checks, const Token *tok) {
use(checks, tok, 2);
}
/**
* Bad pointer usage. If the variable is not a pointer then the usage is ok.
* @param checks all available checks
* @param tok variable token
* @return if error is found, true is returned
*/
static bool use_pointer(std::list<ExecutionPath *> &checks, const Token *tok) {
return use(checks, tok, 3);
}
/**
* Using variable.. if it's a dead pointer the usage is invalid.
* @param checks all available checks
* @param tok variable token
* @return if error is found, true is returned
*/
static bool use_dead_pointer(std::list<ExecutionPath *> &checks, const Token *tok) {
return use(checks, tok, 4);
}
/**
* Using variable.. reading from uninitialized array or pointer data is invalid.
* Example: = x[0];
* @param checks all available checks
* @param tok variable token
* @return if error is found, true is returned
*/
static bool use_array_or_pointer_data(std::list<ExecutionPath *> &checks, const Token *tok) {
return use(checks, tok, 5);
}
/**
* Parse right hand side expression in statement
* @param tok2 start token of rhs
* @param checks the execution paths
*/
void parserhs(const Token *tok2, std::list<ExecutionPath *> &checks) const {
// check variable usages in rhs/index
while (NULL != (tok2 = tok2->next())) {
if (Token::Match(tok2, "[;)=]"))
break;
if (Token::Match(tok2, "%var% ("))
break;
if (tok2->varId() &&
!Token::Match(tok2->previous(), "&|::") &&
!Token::simpleMatch(tok2->tokAt(-2), "& (") &&
!Token::simpleMatch(tok2->next(), "=")) {
// Multiple assignments..
if (Token::Match(tok2->next(), ".|[")) {
const Token * tok3 = tok2;
while (tok3) {
if (Token::Match(tok3->next(), ". %var%"))
tok3 = tok3->tokAt(2);
else if (tok3->strAt(1) == "[")
tok3 = tok3->next()->link();
else
break;
}
if (tok3 && tok3->strAt(1) == "=")
continue;
}
bool foundError;
if (tok2->previous()->str() == "*" || tok2->next()->str() == "[")
foundError = use_array_or_pointer_data(checks, tok2);
else
foundError = use(checks, tok2);
// prevent duplicate error messages
if (foundError) {
bailOutVar(checks, tok2->varId());
}
}
}
}
/** parse tokens. @sa ExecutionPath::parse */
const Token *parse(const Token &tok, std::list<ExecutionPath *> &checks) const {
// Variable declaration..
if (tok.varId() && Token::Match(&tok, "%var% [[;]")) {
const Variable* var2 = symbolDatabase->getVariableFromVarId(tok.varId());
if (var2 && var2->nameToken() == &tok && !var2->isStatic() && !var2->isExtern() && !var2->isConst()) {
if (tok.linkAt(1)) { // array
const Token* endtok = tok.next();
while (endtok->link())
endtok = endtok->link()->next();
if (endtok->str() != ";")
return &tok;
}
const Scope* parent = var2->scope()->nestedIn;
while (parent) {
for (std::list<Variable>::const_iterator j = parent->varlist.begin(); j != parent->varlist.end(); ++j) {
if (j->name() == var2->name()) {
ExecutionPath::bailOutVar(checks, j->varId()); // If there is a variable with the same name in other scopes, this might cause false positives, if there are unexpanded macros
break;
}
}
parent = parent->nestedIn;
}
if (var2->isPointer())
checks.push_back(new UninitVar(owner, var2, symbolDatabase, isC));
else if (var2->typeEndToken()->str() != ">") {
bool stdtype = false; // TODO: change to isC to handle unknown types better
for (const Token* tok2 = var2->typeStartToken(); tok2 != var2->nameToken(); tok2 = tok2->next()) {
if (tok2->isStandardType()) {
stdtype = true;
break;
}
}
if (stdtype && (!var2->isArray() || var2->nameToken()->linkAt(1)->strAt(1) == ";"))
checks.push_back(new UninitVar(owner, var2, symbolDatabase, isC));
}
return &tok;
}
}
if (tok.str() == "return") {
// is there assignment or ternary operator in the return statement?
bool assignment = false;
for (const Token *tok2 = tok.next(); tok2 && tok2->str() != ";"; tok2 = tok2->next()) {
if (tok2->str() == "=" || (!isC && tok2->str() == ">>") || Token::Match(tok2, "(|, &")) {
assignment = true;
break;
}
if (Token::Match(tok2, "[(,] &| %var% [,)]")) {
tok2 = tok2->next();
if (!tok2->isName())
tok2 = tok2->next();
ExecutionPath::bailOutVar(checks, tok2->varId());
}
}
if (!assignment) {
for (const Token *tok2 = tok.next(); tok2 && tok2->str() != ";"; tok2 = tok2->next()) {
if (tok2->isName() && tok2->strAt(1) == "(")
tok2 = tok2->next()->link();
else if (tok2->varId())
use(checks, tok2);
}
}
}
if (tok.varId()) {
// array variable passed as function parameter..
if (Token::Match(tok.previous(), "[(,] %var% [+-,)]")) {
// skip ')'..
const Token *tok2 = tok.next();
while (tok2 && tok2->str() == ")")
tok2 = tok2->next();
// variable is assigned like: "( %var% ) .. ="
if (Token::Match(tok.previous(), "( %var% )") && tok2 && tok2->str() == "=")
ExecutionPath::bailOutVar(checks, tok.varId());
else
use(checks, &tok);
//use_array(checks, &tok);
return &tok;
}
// Used..
if (Token::Match(tok.previous(), "[[(,+-*/|=] %var% ]|)|,|;|%op%")) {
// Taking address of array..
std::list<ExecutionPath *>::const_iterator it;
for (it = checks.begin(); it != checks.end(); ++it) {
UninitVar *c = dynamic_cast<UninitVar *>(*it);
if (c && c->varId == tok.varId()) {
if (c->var->isArray())
bailOutVar(checks, tok.varId());
break;
}
}
// initialize reference variable
if (Token::Match(tok.tokAt(-3), "& %var% ="))
bailOutVar(checks, tok.varId());
else
use(checks, &tok);
return &tok;
}
if ((tok.previous() && tok.previous()->type() == Token::eIncDecOp) || (tok.next() && tok.next()->type() == Token::eIncDecOp)) {
use(checks, &tok);
return &tok;
}
if (Token::Match(tok.previous(), "[;{}] %var% [=[.]")) {
if (tok.next()->str() == ".") {
if (use_dead_pointer(checks, &tok)) {
return &tok;
}
} else {
const Token *tok2 = tok.next();
if (tok2->str() == "[") {
const Token *tok3 = tok2->link();
while (Token::simpleMatch(tok3, "] ["))
tok3 = tok3->next()->link();
// Possible initialization
if (Token::simpleMatch(tok3, "] >>"))
return &tok;
if (Token::simpleMatch(tok3, "] =")) {
if (use_dead_pointer(checks, &tok)) {
return &tok;
}
parserhs(tok2, checks);
tok2 = tok3->next();
}
}
parserhs(tok2, checks);
}
// pointer aliasing?
if (Token::Match(tok.tokAt(2), "%var% ;")) {
pointer_assignment(checks, &tok, tok.tokAt(2));
}
}
if (Token::simpleMatch(tok.next(), "(")) {
use_pointer(checks, &tok);
}
if (Token::Match(tok.tokAt(-2), "[;{}] *")) {
if (Token::simpleMatch(tok.next(), "=")) {
// is the pointer used in the rhs?
bool used = false;
for (const Token *tok2 = tok.tokAt(2); tok2; tok2 = tok2->next()) {
if (Token::Match(tok2, "[,;=(]"))
break;
else if (Token::Match(tok2, "* %varid%", tok.varId())) {
used = true;
break;
}
}
if (used)
use_pointer(checks, &tok);
else
init_pointer(checks, &tok);
} else {
use_pointer(checks, &tok);
}
return &tok;
}
if (Token::Match(tok.next(), "= malloc|kmalloc") || Token::simpleMatch(tok.next(), "= new char [")) {
alloc_pointer(checks, tok.varId());
if (tok.strAt(3) == "(")
return tok.tokAt(3);
}
else if ((!isC && Token::Match(tok.previous(), "<<|>>")) || Token::simpleMatch(tok.next(), "=")) {
// TODO: Don't bail out for "<<" and ">>" if these are
// just computations
ExecutionPath::bailOutVar(checks, tok.varId());
return &tok;
}
if (Token::simpleMatch(tok.next(), "[")) {
const Token *tok2 = tok.next()->link();
if (Token::simpleMatch(tok2 ? tok2->next() : 0, "=")) {
ExecutionPath::bailOutVar(checks, tok.varId());
return &tok;
}
}
if (Token::simpleMatch(tok.previous(), "delete") ||
Token::simpleMatch(tok.tokAt(-3), "delete [ ]")) {
dealloc_pointer(checks, &tok);
return &tok;
}
}
if (Token::Match(&tok, "%var% (") && uvarFunctions.find(tok.str()) == uvarFunctions.end()) {
// sizeof/typeof doesn't dereference. A function name that is all uppercase
// might be an unexpanded macro that uses sizeof/typeof
if (Token::Match(&tok, "sizeof|typeof ("))
return tok.next()->link();
// deallocate pointer
if (Token::Match(&tok, "free|kfree|fclose ( %var% )") ||
Token::Match(&tok, "realloc ( %var%")) {
dealloc_pointer(checks, tok.tokAt(2));
return tok.tokAt(3);
}
// parse usage..
{
std::list<const Token *> var1;
CheckNullPointer::parseFunctionCall(tok, var1, 1);
for (std::list<const Token *>::const_iterator it = var1.begin(); it != var1.end(); ++it) {
// does iterator point at first function parameter?
const bool firstPar(*it == tok.tokAt(2));
// is function memset/memcpy/etc?
if (tok.str().compare(0,3,"mem") == 0)
use_array_mem(checks, *it);
// second parameter for strncpy/strncat/etc
else if (!firstPar && tok.str().compare(0,4,"strn") == 0)
use_array_mem(checks, *it);
else
use_array(checks, *it);
use_dead_pointer(checks, *it);
}
// Using uninitialized pointer is bad if using null pointer is bad
std::list<const Token *> var2;
CheckNullPointer::parseFunctionCall(tok, var2, 0);
for (std::list<const Token *>::const_iterator it = var2.begin(); it != var2.end(); ++it) {
if (std::find(var1.begin(), var1.end(), *it) == var1.end())
use_dead_pointer(checks, *it);
}
}
// strncpy doesn't 0-terminate first parameter
if (Token::Match(&tok, "strncpy ( %var% ,")) {
if (Token::Match(tok.tokAt(4), "%str% ,")) {
if (Token::Match(tok.tokAt(6), "%num% )")) {
const std::size_t len = Token::getStrLength(tok.tokAt(4));
const MathLib::bigint sz = MathLib::toLongNumber(tok.strAt(6));
if (sz >= 0 && len >= static_cast<unsigned long>(sz)) {
init_strncpy(checks, tok.tokAt(2));
return tok.next()->link();
}
}
} else {
init_strncpy(checks, tok.tokAt(2));
return tok.next()->link();
}
}
// memset (not zero terminated)..
if (Token::Match(&tok, "memset ( %var% , !!0 , %num% )")) {
init_memset_nonzero(checks, tok.tokAt(2));
return tok.next()->link();
}
if (Token::Match(&tok, "asm ( %str% )")) {
ExecutionPath::bailOut(checks);
return &tok;
}
// is the variable passed as a parameter to some function?
unsigned int parlevel = 0;
std::set<unsigned int> bailouts;
for (const Token *tok2 = tok.next(); tok2; tok2 = tok2->next()) {
if (tok2->str() == "(")
++parlevel;
else if (tok2->str() == ")") {
if (parlevel <= 1)
break;
--parlevel;
}
else if (Token::Match(tok2, "sizeof|typeof (")) {
tok2 = tok2->next()->link();
if (!tok2)
break;
}
// ticket #2367 : unexpanded macro that uses sizeof|typeof?
else if (Token::Match(tok2, "%type% (") && tok2->isUpperCaseName()) {
tok2 = tok2->next()->link();
if (!tok2)
break;
}
else if (tok2->varId()) {
if (Token::Match(tok2->tokAt(-2), "[(,] *") || Token::Match(tok2->next(), ". %var%")) {
// find function call..
const Token *functionCall = tok2;
while (NULL != (functionCall = functionCall ? functionCall->previous() : 0)) {
if (functionCall->str() == "(")
break;
if (functionCall->str() == ")")
functionCall = functionCall->link();
}
functionCall = functionCall ? functionCall->previous() : 0;
if (functionCall) {
if (functionCall->isName() && !functionCall->isUpperCaseName() && use_dead_pointer(checks, tok2))
ExecutionPath::bailOutVar(checks, tok2->varId());
}
}
// it is possible that the variable is initialized here
if (Token::Match(tok2->previous(), "[(,] %var% [,)]"))
bailouts.insert(tok2->varId());
// array initialization..
if (Token::Match(tok2->previous(), "[,(] %var% [+-]")) {
// if var is array, bailout
for (std::list<ExecutionPath *>::const_iterator it = checks.begin(); it != checks.end(); ++it) {
if ((*it)->varId == tok2->varId()) {
const UninitVar *c = dynamic_cast<const UninitVar *>(*it);
if (c && (c->var->isArray() || (c->var->isPointer() && c->alloc)))
bailouts.insert(tok2->varId());
break;
}
}
}
}
}
for (std::set<unsigned int>::const_iterator it = bailouts.begin(); it != bailouts.end(); ++it)
ExecutionPath::bailOutVar(checks, *it);
}
// function call via function pointer
if (Token::Match(&tok, "( * %var% ) (") ||
(Token::Match(&tok, "( *| %var% .|::") && Token::Match(tok.link()->tokAt(-2), ".|:: %var% ) ("))) {
// is the variable passed as a parameter to some function?
const Token *tok2 = tok.link()->next();
for (const Token* const end2 = tok2->link(); tok2 != end2; tok2 = tok2->next()) {
if (tok2->varId()) {
// it is possible that the variable is initialized here
ExecutionPath::bailOutVar(checks, tok2->varId());
}
}
}
if (tok.str() == "return") {
// Todo: if (!array && ..
if (Token::Match(tok.next(), "%var% ;")) {
use(checks, tok.next());
} else if (Token::Match(tok.next(), "%var% [")) {
use_array_or_pointer_data(checks, tok.next());
}
}
if (tok.varId()) {
if (Token::simpleMatch(tok.previous(), "=")) {
if (Token::Match(tok.tokAt(-3), "& %var% =")) {
bailOutVar(checks, tok.varId());
return &tok;
}
if (!Token::Match(tok.tokAt(-3), ". %var% =")) {
if (!Token::Match(tok.tokAt(-3), "[;{}] %var% =")) {
use(checks, &tok);
return &tok;
}
const unsigned int varid2 = tok.tokAt(-2)->varId();
if (varid2) {
{
use(checks, &tok);
return &tok;
}
}
}
}
if (Token::simpleMatch(tok.next(), ".")) {
bailOutVar(checks, tok.varId());
return &tok;
}
if (Token::simpleMatch(tok.next(), "[")) {
ExecutionPath::bailOutVar(checks, tok.varId());
return &tok;
}
if (Token::Match(tok.tokAt(-2), "[,(=] *")) {
use_pointer(checks, &tok);
return &tok;
}
if (Token::simpleMatch(tok.previous(), "&")) {
ExecutionPath::bailOutVar(checks, tok.varId());
}
}
// Parse "for"
if (Token::Match(&tok, "[;{}] for (")) {
// initialized variables
std::set<unsigned int> varid1;
varid1.insert(0);
// Parse token
const Token *tok2;
// parse setup
for (tok2 = tok.tokAt(3); tok2 != tok.link(); tok2 = tok2->next()) {
if (tok2->str() == ";")
break;
if (tok2->varId())
varid1.insert(tok2->varId());
}
if (tok2 == tok.link())
return &tok;
// parse condition
if (Token::Match(tok2, "; %var% <|<=|>=|> %num% ;")) {
// If the variable hasn't been initialized then call "use"
if (varid1.find(tok2->next()->varId()) == varid1.end())
use(checks, tok2->next());
}
// goto stepcode
tok2 = tok2->next();
while (tok2 && tok2->str() != ";")
tok2 = tok2->next();
// parse the stepcode
if (Token::Match(tok2, "; ++|-- %var% ) {") ||
Token::Match(tok2, "; %var% ++|-- ) {")) {
// get id of variable..
unsigned int varid = tok2->next()->varId();
if (!varid)
varid = tok2->tokAt(2)->varId();
// Check that the variable hasn't been initialized and
// that it isn't initialized in the body..
if (varid1.find(varid) == varid1.end()) {
for (const Token *tok3 = tok2->tokAt(5); tok3 && tok3 != tok2->linkAt(4); tok3 = tok3->next()) {
if (tok3->varId() == varid) {
varid = 0; // variable is used.. maybe it's initialized. clear the variable id.
break;
}
}
// If the variable isn't initialized in the body call "use"
if (varid != 0) {
// goto variable
tok2 = tok2->next();
if (!tok2->varId())
tok2 = tok2->next();
// call "use"
use(checks, tok2);
}
}
}
}
return &tok;
}
bool parseCondition(const Token &tok, std::list<ExecutionPath *> &checks) {
if (tok.varId() && Token::Match(&tok, "%var% <|<=|==|!=|)"))
use(checks, &tok);
else if (Token::Match(&tok, "!| %var% [") && !Token::simpleMatch(skipBrackets(tok.next()), "="))
use_array_or_pointer_data(checks, tok.str() == "!" ? tok.next() : &tok);
else if (Token::Match(&tok, "!| %var% (")) {
const Token * const ftok = (tok.str() == "!") ? tok.next() : &tok;
std::list<const Token *> var1;
CheckNullPointer::parseFunctionCall(*ftok, var1, 1);
for (std::list<const Token *>::const_iterator it = var1.begin(); it != var1.end(); ++it) {
// is function memset/memcpy/etc?
if (ftok->str().compare(0,3,"mem") == 0)
use_array_mem(checks, *it);
else
use_array(checks, *it);
}
}
else if (Token::Match(&tok, "! %var% )")) {
use(checks, &tok);
return false;
}
return ExecutionPath::parseCondition(tok, checks);
}
void parseLoopBody(const Token *tok, std::list<ExecutionPath *> &checks) const {
while (tok) {
if (tok->str() == "{" || tok->str() == "}" || tok->str() == "for")
return;
if (Token::simpleMatch(tok, "if (")) {
// bail out all variables that are used in the condition
const Token* const end2 = tok->linkAt(1);
for (const Token *tok2 = tok->tokAt(2); tok2 != end2; tok2 = tok2->next()) {
if (tok2->varId())
ExecutionPath::bailOutVar(checks, tok2->varId());
}
}
const Token *next = parse(*tok, checks);
tok = next->next();
}
}
public:
/** Functions that don't handle uninitialized variables well */
static std::set<std::string> uvarFunctions;
static void analyseFunctions(const Token * const tokens, std::set<std::string> &func) {
for (const Token *tok = tokens; tok; tok = tok->next()) {
if (tok->str() == "{") {
tok = tok->link();
continue;
}
if (tok->str() != "::" && Token::Match(tok->next(), "%var% ( %type%")) {
if (!Token::Match(tok->linkAt(2), ") [{;]"))
continue;
const Token *tok2 = tok->tokAt(3);
while (tok2 && tok2->str() != ")") {
if (tok2->str() == ",")
tok2 = tok2->next();
if (Token::Match(tok2, "%type% %var% ,|)") && tok2->isStandardType()) {
tok2 = tok2->tokAt(2);
continue;
}
if (tok2->isStandardType() && Token::Match(tok2, "%type% & %var% ,|)")) {
const unsigned int varid(tok2->tokAt(2)->varId());
// flags for read/write
bool r = false, w = false;
// check how the variable is used in the function
unsigned int indentlevel = 0;
for (const Token *tok3 = tok2; tok3; tok3 = tok3->next()) {
if (tok3->str() == "{")
++indentlevel;
else if (tok3->str() == "}") {
if (indentlevel <= 1)
break;
--indentlevel;
} else if (indentlevel == 0 && tok3->str() == ";")
break;
else if (indentlevel >= 1 && tok3->varId() == varid) {
if (tok3->previous()->type() == Token::eIncDecOp ||
tok3->next()->type() == Token::eIncDecOp) {
r = true;
}
else {
w = true;
break;
}
}
}
if (!r || w)
break;
tok2 = tok2->tokAt(3);
continue;
}
if (Token::Match(tok2, "const %type% &|*| const| %var% ,|)") && tok2->next()->isStandardType()) {
tok2 = tok2->tokAt(3);
while (tok2->isName())
tok2 = tok2->next();
continue;
}
if (Token::Match(tok2, "const %type% %var% [ ] ,|)") && tok2->next()->isStandardType()) {
tok2 = tok2->tokAt(5);
continue;
}
/// @todo enable this code. if pointer is written in function then dead pointer is invalid but valid pointer is ok.
/*
if (Token::Match(tok2, "const| struct| %type% * %var% ,|)"))
{
while (tok2->isName())
tok2 = tok2->next();
tok2 = tok2->tokAt(2);
continue;
}
*/
break;
}
// found simple function..
if (tok2 && tok2->link() == tok->tokAt(2))
func.insert(tok->next()->str());
}
}
}
};
/** Functions that don't handle uninitialized variables well */
std::set<std::string> UninitVar::uvarFunctions;
/// @}
void CheckUninitVar::analyse(const Token * const tokens, std::set<std::string> &func) const
{
UninitVar::analyseFunctions(tokens, func);
}
void CheckUninitVar::saveAnalysisData(const std::set<std::string> &data) const
{
UninitVar::uvarFunctions.insert(data.begin(), data.end());
}
void CheckUninitVar::executionPaths()
{
// check if variable is accessed uninitialized..
{
// no writing if multiple threads are used (TODO: thread safe analysis?)
if (_settings->_jobs == 1)
UninitVar::analyseFunctions(_tokenizer->tokens(), UninitVar::uvarFunctions);
UninitVar c(this, _tokenizer->getSymbolDatabase(), _tokenizer->isC());
checkExecutionPaths(_tokenizer->getSymbolDatabase(), &c);
}
}
void CheckUninitVar::check()
{
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
std::list<Scope>::const_iterator func_scope;
// scan every function
for (func_scope = symbolDatabase->scopeList.begin(); func_scope != symbolDatabase->scopeList.end(); ++func_scope) {
// only check functions
if (func_scope->type == Scope::eFunction) {
checkScope(&*func_scope);
}
}
}
void CheckUninitVar::checkScope(const Scope* scope)
{
for (std::list<Variable>::const_iterator i = scope->varlist.begin(); i != scope->varlist.end(); ++i) {
if ((i->type() && !i->isPointer()) || i->isStatic() || i->isExtern() || i->isConst() || i->isArray() || i->isReference())
continue;
if (i->nameToken()->strAt(1) == "(")
continue;
bool forHead = false; // Don't check variables declared in header of a for loop
for (const Token* tok = i->typeStartToken(); tok; tok = tok->previous()) {
if (tok->str() == "(") {
forHead = true;
break;
} else if (tok->str() == "{" || tok->str() == ";" || tok->str() == "}")
break;
}
if (forHead)
continue;
bool stdtype = _tokenizer->isC();
const Token* tok = i->typeStartToken();
for (; tok->str() != ";" && tok->str() != "<"; tok = tok->next()) {
if (tok->isStandardType())
stdtype = true;
}
while (tok && tok->str() != ";")
tok = tok->next();
if (stdtype || i->isPointer())
checkScopeForVariable(tok, *i, NULL);
}
for (std::list<Scope*>::const_iterator i = scope->nestedList.begin(); i != scope->nestedList.end(); ++i) {
if (!(*i)->isClassOrStruct())
checkScope(*i);
}
}
bool CheckUninitVar::checkScopeForVariable(const Token *tok, const Variable& var, bool * const possibleInit)
{
const bool suppressErrors(possibleInit && *possibleInit);
if (possibleInit)
*possibleInit = false;
bool ret = false;
unsigned int number_of_if = 0;
// variables that are known to be non-zero
std::set<unsigned int> notzero;
for (; tok; tok = tok->next()) {
// End of scope..
if (tok->str() == "}") {
if (number_of_if && possibleInit)
*possibleInit = true;
// might be a noreturn function..
if (_tokenizer->IsScopeNoReturn(tok))
return true;
break;
}
// Unconditional inner scope..
if (tok->str() == "{" && Token::Match(tok->previous(), "[;{}]")) {
if (checkScopeForVariable(tok->next(), var, possibleInit))
return true;
tok = tok->link();
continue;
}
// assignment with nonzero constant..
if (Token::Match(tok->previous(), "[;{}] %var% = - %var% ;") && tok->varId() > 0)
notzero.insert(tok->varId());
// Inner scope..
if (Token::simpleMatch(tok, "if (")) {
// initialization / usage in condition..
if (checkIfForWhileHead(tok->next(), var, suppressErrors, bool(number_of_if == 0)))
return true;
// checking if a not-zero variable is zero => bail out
if (Token::Match(tok, "if ( %var% )") && notzero.find(tok->tokAt(2)->varId()) != notzero.end())
return true; // this scope is not fully analysed => return true
// goto the {
tok = tok->next()->link()->next();
if (!tok)
break;
if (tok->str() == "{") {
bool possibleInitIf(number_of_if > 0 || suppressErrors);
const bool initif = checkScopeForVariable(tok->next(), var, &possibleInitIf);
// goto the }
tok = tok->link();
if (!Token::simpleMatch(tok, "} else {")) {
if (initif || possibleInitIf) {
++number_of_if;
if (number_of_if >= 2)
return true;
}
} else {
// goto the {
tok = tok->tokAt(2);
bool possibleInitElse(number_of_if > 0 || suppressErrors);
const bool initelse = checkScopeForVariable(tok->next(), var, &possibleInitElse);
// goto the }
tok = tok->link();
if (initif && initelse)
return true;
if (initif || initelse || possibleInitElse)
++number_of_if;
}
}
}
// = { .. }
if (Token::simpleMatch(tok, "= {")) {
// end token
const Token *end = tok->next()->link();
// If address of variable is taken in the block then bail out
if (Token::findmatch(tok->tokAt(2), "& %varid%", end, var.varId()))
return true;
// Skip block
tok = end;
continue;
}
// skip sizeof / offsetof
if (Token::Match(tok, "sizeof|typeof|offsetof|decltype ("))
tok = tok->next()->link();
// for..
if (Token::simpleMatch(tok, "for (")) {
// is variable initialized in for-head (don't report errors yet)?
if (checkIfForWhileHead(tok->next(), var, true, false))
return true;
// goto the {
const Token *tok2 = tok->next()->link()->next();
if (tok2 && tok2->str() == "{") {
bool possibleinit = true;
bool init = checkScopeForVariable(tok2->next(), var, &possibleinit);
// variable is initialized in the loop..
if (possibleinit || init)
return true;
// is variable used in for-head?
if (!suppressErrors) {
checkIfForWhileHead(tok->next(), var, false, bool(number_of_if == 0));
}
}
}
// TODO: handle loops, try, etc
if (Token::simpleMatch(tok, ") {") || Token::Match(tok, "%var% {")) {
return true;
}
// bailout if there is assembler code
if (Token::simpleMatch(tok, "asm (")) {
return true;
}
if (Token::Match(tok, "return|break|continue|throw|goto"))
ret = true;
else if (ret && tok->str() == ";")
return true;
// variable is seen..
if (tok && tok->varId() == var.varId()) {
// Use variable
if (!suppressErrors && isVariableUsage(tok, var.isPointer()))
uninitvarError(tok, tok->str());
else
// assume that variable is assigned
return true;
}
}
return ret;
}
bool CheckUninitVar::checkIfForWhileHead(const Token *startparanthesis, const Variable& var, bool suppressErrors, bool isuninit)
{
const Token * const endpar = startparanthesis->link();
for (const Token *tok = startparanthesis->next(); tok && tok != endpar; tok = tok->next()) {
if (tok->varId() == var.varId()) {
if (isVariableUsage(tok, var.isPointer())) {
if (!suppressErrors)
uninitvarError(tok, tok->str());
else
continue;
}
return true;
}
if (Token::Match(tok, "sizeof|decltype|offsetof ("))
tok = tok->next()->link();
if (!isuninit && tok->str() == "&&")
suppressErrors = true;
}
return false;
}
bool CheckUninitVar::isVariableUsage(const Token *vartok, bool pointer) const
{
if (vartok->previous()->str() == "return")
return true;
if (Token::Match(vartok->previous(), "++|--|%op%")) {
if (vartok->previous()->str() == ">>" && _tokenizer->isCPP()) {
// assume that variable is initialized
return false;
}
// is there something like: ; "*((&var ..expr.. =" => the variable is assigned
if (vartok->previous()->str() == "&") {
const Token *tok2 = vartok->tokAt(-2);
if (Token::simpleMatch(tok2,")"))
tok2 = tok2->link()->previous();
while (tok2 && tok2->str() == "(")
tok2 = tok2->previous();
while (tok2 && tok2->str() == "*")
tok2 = tok2->previous();
if (Token::Match(tok2, "[;{}] *")) {
// there is some such code before vartok: "[*]+ [(]* &"
// determine if there is a = after vartok
for (tok2 = vartok; tok2; tok2 = tok2->next()) {
if (Token::Match(tok2, "[;{}]"))
break;
if (tok2->str() == "=")
return false;
}
}
}
if (vartok->previous()->str() != "&" || !Token::Match(vartok->tokAt(-2), "[(,=?:]")) {
return true;
}
}
bool unknown = false;
if (pointer && CheckNullPointer::isPointerDeRef(vartok, unknown, _tokenizer->getSymbolDatabase())) {
// function parameter?
bool functionParameter = false;
if (Token::Match(vartok->tokAt(-2), "%var% (") || vartok->previous()->str() == ",")
functionParameter = true;
// if this is not a function parameter report this dereference as variable usage
if (!functionParameter)
return true;
}
if (_tokenizer->isCPP() && Token::Match(vartok->next(), "<<|>>")) {
// Is variable a known POD type then this is a variable usage,
// otherwise we assume it's not.
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(vartok->varId());
if (var && var->typeStartToken()->isStandardType())
return true;
return false;
}
if (Token::Match(vartok->next(), "++|--|%op%"))
return true;
if (vartok->strAt(1) == "]")
return true;
return false;
}
void CheckUninitVar::uninitstringError(const Token *tok, const std::string &varname, bool strncpy_)
{
reportError(tok, Severity::error, "uninitstring", "Dangerous usage of '" + varname + "'" + (strncpy_ ? " (strncpy doesn't always 0-terminate it)" : " (not 0-terminated)"));
}
void CheckUninitVar::uninitdataError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::error, "uninitdata", "Data is allocated but not initialized: " + varname);
}
void CheckUninitVar::uninitvarError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::error, "uninitvar", "Uninitialized variable: " + varname);
}
Jump to Line
Something went wrong with that request. Please try again.