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Fixed #5017 (New check: division by zero, otherwise condition is redundant)

This commit is contained in:
Daniel Marjamäki 2013-09-07 07:40:10 +02:00
parent 40c5924292
commit 83c460fc56
3 changed files with 143 additions and 0 deletions
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68
lib/checkother.cpp
View File

@ -2155,6 +2155,74 @@ void CheckOther::zerodivError(const Token *tok)
reportError(tok, Severity::error, "zerodiv", "Division by zero.");
}
//---------------------------------------------------------------------------
void CheckOther::checkZeroDivisionOrUselessCondition()
{
if (!_settings->isEnabled("warning"))
return;
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
const std::size_t numberOfFunctions = symbolDatabase->functionScopes.size();
for (std::size_t functionIndex = 0; functionIndex < numberOfFunctions; ++functionIndex) {
const Scope * scope = symbolDatabase->functionScopes[functionIndex];
for (const Token* tok = scope->classStart->next(); tok != scope->classEnd; tok = tok->next()) {
if (Token::Match(tok, "[/%] %var% !!.")) {
const unsigned int varid = tok->next()->varId();
const Variable *var = tok->next()->variable();
if (!var)
continue;
bool isVarUnsigned = var->typeEndToken()->isUnsigned();
for (const Token *typetok = var->typeStartToken(); typetok != var->typeEndToken(); typetok = typetok->next()) {
if (typetok->isUnsigned()) {
isVarUnsigned = true;
break;
}
}
for (const Token *tok2 = tok->tokAt(2); tok2; tok2 = tok2->next()) {
if (tok2->varId() == varid)
break;
if (tok2->str() == "}")
break;
if (Token::Match(tok2, "%var% (") && tok2->str() != "if" && (var->isGlobal() || !tok2->function()))
break;
if (isVarUnsigned && Token::Match(tok2, "(|%oror%|&& 0 < %varid% &&|%oror%|)", varid)) {
zerodivcondError(tok2,tok);
continue;
}
if (isVarUnsigned && Token::Match(tok2, "(|%oror%|&& 1 <= %varid% &&|%oror%|)", varid)) {
zerodivcondError(tok2,tok);
continue;
}
if (Token::Match(tok2, "(|%oror%|&& !| %varid% &&|%oror%|)", varid)) {
zerodivcondError(tok2,tok);
continue;
}
}
}
}
}
}
void CheckOther::zerodivcondError(const Token *tokcond, const Token *tokdiv)
{
std::list<const Token *> callstack;
while (Token::Match(tokcond, "(|%oror%|&&"))
tokcond = tokcond->next();
if (tokcond && tokdiv) {
callstack.push_back(tokcond);
callstack.push_back(tokdiv);
}
std::string condition;
if (Token::Match(tokcond, "%num% <|<=")) {
condition = tokcond->strAt(2) + ((tokcond->strAt(1) == "<") ? ">" : ">=") + tokcond->str();
} else if (tokcond) {
if (tokcond->str() == "!")
condition = tokcond->next()->str() + "==0";
else
condition = tokcond->str() + "!=0";
}
const std::string linenr(MathLib::longToString(tokdiv ? tokdiv->linenr() : 0));
reportError(callstack, Severity::warning, "zerodivcond", "Either the condition '"+condition+"' is useless or there is division by zero at line " + linenr + ".");
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------

9
lib/checkother.h
View File

@ -90,6 +90,7 @@ public:
checkOther.invalidFunctionUsage();
checkOther.checkZeroDivision();
checkOther.checkZeroDivisionOrUselessCondition();
checkOther.checkMathFunctions();
checkOther.checkCCTypeFunctions();
@ -163,6 +164,9 @@ public:
/** @brief %Check zero division*/
void checkZeroDivision();
/** @brief %Check zero division / useless condition */
void checkZeroDivisionOrUselessCondition();
/** @brief Check for NaN (not-a-number) in an arithmetic expression */
void checkNanInArithmeticExpression();
@ -286,6 +290,7 @@ private:
void variableScopeError(const Token *tok, const std::string &varname);
void strPlusCharError(const Token *tok);
void zerodivError(const Token *tok);
void zerodivcondError(const Token *tokcond, const Token *tokdiv);
void nanInArithmeticExpressionError(const Token *tok);
void mathfunctionCallError(const Token *tok, const unsigned int numParam = 1);
void cctypefunctionCallError(const Token *tok, const std::string &functionName, const std::string &value);
@ -332,6 +337,7 @@ private:
c.sprintfOverlappingDataError(0, "varname");
c.udivError(0, false);
c.zerodivError(0);
c.zerodivcondError(0,0);
c.mathfunctionCallError(0);
c.misusedScopeObjectError(NULL, "varname");
c.doubleFreeError(0, "varname");
@ -411,6 +417,9 @@ private:
"* cast the return values of getc(),fgetc() and getchar() to character and compare it to EOF\n"
"* provide too big sleep times on POSIX systems\n"
// warning
"* either division by zero or useless condition\n"
//performance
"* redundant data copying for const variable\n"
"* subsequent assignment or copying to a variable or buffer\n"

66
test/testother.cpp
View File

@ -44,6 +44,8 @@ private:
TEST_CASE(zeroDiv6);
TEST_CASE(zeroDiv7); // #4930
TEST_CASE(zeroDivCond); // division by zero / useless condition
TEST_CASE(nanInArithmeticExpression);
TEST_CASE(sprintf1); // Dangerous usage of sprintf
@ -428,6 +430,70 @@ private:
"[test.cpp:3]: (error) Division by zero.\n", errout.str());
}
void zeroDivCond() {
check("void f(unsigned int x) {\n"
" int y = 17 / x;\n"
" if (x > 0) {}\n"
"}");
ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:2]: (warning) Either the condition 'x>0' is useless or there is division by zero at line 2.\n", errout.str());
check("void f(unsigned int x) {\n"
" int y = 17 / x;\n"
" if (x >= 1) {}\n"
"}");
ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:2]: (warning) Either the condition 'x>=1' is useless or there is division by zero at line 2.\n", errout.str());
check("void f(int x) {\n"
" int y = 17 / x;\n"
" if (x == 0) {}\n"
"}");
ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:2]: (warning) Either the condition 'x==0' is useless or there is division by zero at line 2.\n", errout.str());
check("void f(unsigned int x) {\n"
" int y = 17 / x;\n"
" if (x != 0) {}\n"
"}");
ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:2]: (warning) Either the condition 'x!=0' is useless or there is division by zero at line 2.\n", errout.str());
// avoid false positives when variable is changed after division
check("void f() {\n"
" unsigned int x = do_something();\n"
" int y = 17 / x;\n"
" x = some+calculation;\n"
" if (x != 0) {}\n"
"}");
ASSERT_EQUALS("", errout.str());
{
// function is called that might modify global variable
check("void do_something();\n"
"int x;\n"
"void f() {\n"
" int y = 17 / x;\n"
" do_something();\n"
" if (x != 0) {}\n"
"}");
ASSERT_EQUALS("", errout.str());
// function is called. but don't care, variable is local
check("void do_something();\n"
"void f() {\n"
" int x = some + calculation;\n"
" int y = 17 / x;\n"
" do_something();\n"
" if (x != 0) {}\n"
"}");
ASSERT_EQUALS("[test.cpp:6] -> [test.cpp:4]: (warning) Either the condition 'x!=0' is useless or there is division by zero at line 4.\n", errout.str());
}
check("int x;\n"
"void f() {\n"
" int y = 17 / x;\n"
" while (y || x == 0) { x--; }\n"
"}");
ASSERT_EQUALS("", errout.str());
}
void nanInArithmeticExpression() {
check("void f()\n"
"{\n"