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Use valueflow in unsigned less than zero checker #1630

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Merged
danmar merged 1 commit into from
Jan 31, 2019
Merged

Use valueflow in unsigned less than zero checker #1630

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82 changes: 31 additions & 51 deletions lib/checkother.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2012,10 +2012,6 @@ void CheckOther::checkSignOfUnsignedVariable()
if (!mSettings->isEnabled(Settings::STYLE))
return;

const bool inconclusive = mTokenizer->codeWithTemplates();
if (inconclusive && !mSettings->inconclusive)
return;

const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();

for (const Scope * scope : symbolDatabase->functionScopes) {
Expand All @@ -2024,80 +2020,64 @@ void CheckOther::checkSignOfUnsignedVariable()
if (!tok->isComparisonOp() || !tok->astOperand1() || !tok->astOperand2())
continue;

if (Token::Match(tok, "<|<= 0") && tok->next() == tok->astOperand2()) {
const ValueFlow::Value *v1 = tok->astOperand1()->getValue(0);
const ValueFlow::Value *v2 = tok->astOperand2()->getValue(0);

if (Token::Match(tok, "<|<=") && v2 && v2->isKnown()) {
const ValueType* vt = tok->astOperand1()->valueType();
if (vt && vt->pointer)
pointerLessThanZeroError(tok, inconclusive);
pointerLessThanZeroError(tok, v2);
if (vt && vt->sign == ValueType::UNSIGNED)
unsignedLessThanZeroError(tok, tok->astOperand1()->expressionString(), inconclusive);
} else if (Token::Match(tok->previous(), "0 >|>=") && tok->previous() == tok->astOperand1()) {
unsignedLessThanZeroError(tok, v2, tok->astOperand1()->expressionString());
} else if (Token::Match(tok, ">|>=") && v1 && v1->isKnown()) {
const ValueType* vt = tok->astOperand2()->valueType();
if (vt && vt->pointer)
pointerLessThanZeroError(tok, inconclusive);
pointerLessThanZeroError(tok, v1);
if (vt && vt->sign == ValueType::UNSIGNED)
unsignedLessThanZeroError(tok, tok->astOperand2()->expressionString(), inconclusive);
} else if (Token::simpleMatch(tok, ">= 0") && tok->next() == tok->astOperand2()) {
unsignedLessThanZeroError(tok, v1, tok->astOperand2()->expressionString());
} else if (Token::simpleMatch(tok, ">=") && v2 && v2->isKnown()) {
const ValueType* vt = tok->astOperand1()->valueType();
if (vt && vt->pointer)
pointerPositiveError(tok, inconclusive);
pointerPositiveError(tok, v2);
if (vt && vt->sign == ValueType::UNSIGNED)
unsignedPositiveError(tok, tok->astOperand1()->str(), inconclusive);
} else if (Token::simpleMatch(tok->previous(), "0 <=") && tok->previous() == tok->astOperand1()) {
unsignedPositiveError(tok, v2, tok->astOperand1()->expressionString());
} else if (Token::simpleMatch(tok, "<=") && v1 && v1->isKnown()) {
const ValueType* vt = tok->astOperand2()->valueType();
if (vt && vt->pointer)
pointerPositiveError(tok, inconclusive);
pointerPositiveError(tok, v1);
if (vt && vt->sign == ValueType::UNSIGNED)
unsignedPositiveError(tok, tok->astOperand2()->str(), inconclusive);
unsignedPositiveError(tok, v1, tok->astOperand2()->expressionString());
}
}
}
}

void CheckOther::unsignedLessThanZeroError(const Token *tok, const std::string &varname, bool inconclusive)
void CheckOther::unsignedLessThanZeroError(const Token *tok, const ValueFlow::Value * v, const std::string &varname)
{
if (inconclusive) {
reportError(tok, Severity::style, "unsignedLessThanZero",
"$symbol:" + varname + "\n"
"Checking if unsigned expression '$symbol' is less than zero. This might be a false warning.\n"
"Checking if unsigned expression '$symbol' is less than zero. An unsigned "
"variable will never be negative so it is either pointless or an error to check if it is. "
"It's not known if the used constant is a template parameter or not and therefore "
"this message might be a false warning.", CWE570, true);
} else {
reportError(tok, Severity::style, "unsignedLessThanZero",
"$symbol:" + varname + "\n"
"Checking if unsigned expression '$symbol' is less than zero.\n"
"The unsigned expression '$symbol' will never be negative so it "
"is either pointless or an error to check if it is.", CWE570, false);
}
reportError(getErrorPath(tok, v, "Unsigned less than zero"), Severity::style, "unsignedLessThanZero",
"$symbol:" + varname + "\n"
"Checking if unsigned expression '$symbol' is less than zero.\n"
"The unsigned expression '$symbol' will never be negative so it "
"is either pointless or an error to check if it is.", CWE570, false);
}

void CheckOther::pointerLessThanZeroError(const Token *tok, bool inconclusive)
void CheckOther::pointerLessThanZeroError(const Token *tok, const ValueFlow::Value *v)
{
reportError(tok, Severity::style, "pointerLessThanZero",
"A pointer can not be negative so it is either pointless or an error to check if it is.", CWE570, inconclusive);
reportError(getErrorPath(tok, v, "Pointer less than zero"), Severity::style, "pointerLessThanZero",
"A pointer can not be negative so it is either pointless or an error to check if it is.", CWE570, false);
}

void CheckOther::unsignedPositiveError(const Token *tok, const std::string &varname, bool inconclusive)
void CheckOther::unsignedPositiveError(const Token *tok, const ValueFlow::Value * v, const std::string &varname)
{
if (inconclusive) {
reportError(tok, Severity::style, "unsignedPositive",
"$symbol:" + varname + "\n"
"Unsigned variable '$symbol' can't be negative so it is unnecessary to test it.\n"
"The unsigned variable '$symbol' can't be negative so it is unnecessary to test it. "
"It's not known if the used constant is a "
"template parameter or not and therefore this message might be a false warning", CWE570, true);
} else {
reportError(tok, Severity::style, "unsignedPositive",
"$symbol:" + varname + "\n"
"Unsigned variable '$symbol' can't be negative so it is unnecessary to test it.", CWE570, false);
}
reportError(getErrorPath(tok, v, "Unsigned positive"), Severity::style, "unsignedPositive",
"$symbol:" + varname + "\n"
"Unsigned expression '$symbol' can't be negative so it is unnecessary to test it.", CWE570, false);
}

void CheckOther::pointerPositiveError(const Token *tok, bool inconclusive)
void CheckOther::pointerPositiveError(const Token *tok, const ValueFlow::Value * v)
{
reportError(tok, Severity::style, "pointerPositive",
"A pointer can not be negative so it is either pointless or an error to check if it is not.", CWE570, inconclusive);
reportError(getErrorPath(tok, v, "Pointer positive"), Severity::style, "pointerPositive",
"A pointer can not be negative so it is either pointless or an error to check if it is not.", CWE570, false);
}

/* check if a constructor in given class scope takes a reference */
Expand Down
16 changes: 8 additions & 8 deletions lib/checkother.h
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Original file line number Diff line number Diff line change
Expand Up @@ -252,10 +252,10 @@ class CPPCHECKLIB CheckOther : public Check {
void duplicateExpressionTernaryError(const Token *tok, ErrorPath errors);
void duplicateBreakError(const Token *tok, bool inconclusive);
void unreachableCodeError(const Token* tok, bool inconclusive);
void unsignedLessThanZeroError(const Token *tok, const std::string &varname, bool inconclusive);
void pointerLessThanZeroError(const Token *tok, bool inconclusive);
void unsignedPositiveError(const Token *tok, const std::string &varname, bool inconclusive);
void pointerPositiveError(const Token *tok, bool inconclusive);
void unsignedLessThanZeroError(const Token *tok, const ValueFlow::Value *v, const std::string &varname);
void pointerLessThanZeroError(const Token *tok, const ValueFlow::Value *v);
void unsignedPositiveError(const Token *tok, const ValueFlow::Value *v, const std::string &varname);
void pointerPositiveError(const Token *tok, const ValueFlow::Value *v);
void SuspiciousSemicolonError(const Token *tok);
void negativeBitwiseShiftError(const Token *tok, int op);
void redundantCopyError(const Token *tok, const std::string &varname);
Expand Down Expand Up @@ -318,10 +318,10 @@ class CPPCHECKLIB CheckOther : public Check {
c.duplicateExpressionTernaryError(nullptr, errorPath);
c.duplicateBreakError(nullptr, false);
c.unreachableCodeError(nullptr, false);
c.unsignedLessThanZeroError(nullptr, "varname", false);
c.unsignedPositiveError(nullptr, "varname", false);
c.pointerLessThanZeroError(nullptr, false);
c.pointerPositiveError(nullptr, false);
c.unsignedLessThanZeroError(nullptr, nullptr, "varname");
c.unsignedPositiveError(nullptr, nullptr, "varname");
c.pointerLessThanZeroError(nullptr, nullptr);
c.pointerPositiveError(nullptr, nullptr);
c.SuspiciousSemicolonError(nullptr);
c.incompleteArrayFillError(nullptr, "buffer", "memset", false);
c.varFuncNullUBError(nullptr);
Expand Down
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