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New Check: Compare pointer with '\0' (#4070)

This commit is contained in:
PKEuS 2014-05-21 19:10:14 +02:00
parent cdfed32500
commit d19eabde42
4 changed files with 53 additions and 14 deletions
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26
lib/checkother.cpp
View File

@ -2900,16 +2900,18 @@ void CheckOther::checkSuspiciousStringCompare()
if (Token::simpleMatch(varTok->tokAt(1), "[") || Token::simpleMatch(litTok->tokAt(1), "["))
continue;
if ((varTok->type() == Token::eString || varTok->type() == Token::eVariable) && (litTok->type() == Token::eString || litTok->type() == Token::eVariable) && litTok->type() != varTok->type()) {
if (varTok->type() == Token::eString)
std::swap(varTok, litTok);
if (varTok->type() == Token::eString || varTok->type() == Token::eNumber)
std::swap(varTok, litTok);
const Variable *var = varTok->variable();
if (!var)
continue;
const Variable *var = varTok->variable();
if (var) {
if (_tokenizer->isC() ||
(var->isPointer() && varTok->strAt(-1) != "*" && !Token::Match(varTok->next(), "[.([]")))
suspiciousStringCompareError(tok, var->name());
}
if (_tokenizer->isC() ||
(var->isPointer() && varTok->strAt(-1) != "*" && !Token::Match(varTok->next(), "[.([]"))) {
if (litTok->type() == Token::eString)
suspiciousStringCompareError(tok, var->name());
else if (litTok->type() == Token::eNumber && litTok->originalName() == "'\\0'")
suspiciousStringCompareError_char(tok, var->name());
}
}
}
@ -2921,6 +2923,12 @@ void CheckOther::suspiciousStringCompareError(const Token* tok, const std::strin
"String literal compared with variable '" + var + "'. Did you intend to use strcmp() instead?");
}
void CheckOther::suspiciousStringCompareError_char(const Token* tok, const std::string& var)
{
reportError(tok, Severity::warning, "charLiteralWithCharPtrCompare",
"Char literal compared with pointer '" + var + "'. Did you intend to dereference it?");
}
//-----------------------------------------------------------------------------
// Check is a comparison of two variables leads to condition, which is
// always true or false.

3
lib/checkother.h
View File

@ -316,6 +316,7 @@ private:
void alwaysTrueFalseStringCompareError(const Token *tok, const std::string& str1, const std::string& str2);
void alwaysTrueStringVariableCompareError(const Token *tok, const std::string& str1, const std::string& str2);
void suspiciousStringCompareError(const Token* tok, const std::string& var);
void suspiciousStringCompareError_char(const Token* tok, const std::string& var);
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);
@ -380,6 +381,7 @@ private:
c.clarifyStatementError(0);
c.incorrectStringCompareError(0, "substr", "\"Hello World\"");
c.suspiciousStringCompareError(0, "foo");
c.suspiciousStringCompareError_char(0, "foo");
c.incorrectStringBooleanError(0, "\"Hello World\"");
c.duplicateBranchError(0, 0);
c.duplicateExpressionError(0, 0, "&&");
@ -456,6 +458,7 @@ private:
"* suspicious condition (runtime comparison of string literals)\n"
"* suspicious condition (string literals as boolean)\n"
"* suspicious comparison of a string literal with a char* variable\n"
"* suspicious comparison of '\\0' with a char* variable\n"
"* duplicate break statement\n"
"* unreachable code\n"
"* testing if unsigned variable is negative\n"

10
lib/tokenize.cpp
View File

@ -1833,11 +1833,12 @@ void Tokenizer::simplifyNull()
for (Token *tok = list.front(); tok; tok = tok->next()) {
if (tok->str() == "NULL" && !Token::Match(tok->previous(), "[(,] NULL [,)]"))
tok->str("0");
else if (tok->str() == "__null" || tok->str() == "'\\0'" || tok->str() == "'\\x0'")
else if (tok->str() == "__null" || tok->str() == "'\\0'" || tok->str() == "'\\x0'") {
tok->originalName(tok->str());
tok->str("0");
else if (tok->isNumber() &&
MathLib::isInt(tok->str()) &&
MathLib::toLongNumber(tok->str()) == 0)
} else if (tok->isNumber() &&
MathLib::isInt(tok->str()) &&
MathLib::toLongNumber(tok->str()) == 0)
tok->str("0");
}
@ -4394,7 +4395,6 @@ void Tokenizer::simplifyCompoundAssignment()
// Remove the whole statement if it says: "+=0;", "-=0;", "*=1;" or "/=1;"
if (Token::Match(tok, "+=|-= 0 ;") ||
Token::Match(tok, "+=|-= '\\0' ;") ||
Token::simpleMatch(tok, "|= 0 ;") ||
Token::Match(tok, "*=|/= 1 ;")) {
tok = tok1;

28
test/testother.cpp
View File

@ -165,6 +165,7 @@ private:
TEST_CASE(alwaysTrueFalseStringCompare);
TEST_CASE(suspiciousStringCompare);
TEST_CASE(suspiciousStringCompare_char);
TEST_CASE(checkSignOfUnsignedVariable);
TEST_CASE(checkSignOfPointer);
@ -5231,6 +5232,33 @@ private:
ASSERT_EQUALS("", errout.str());
}
void suspiciousStringCompare_char() {
check("bool foo(char* c) {\n"
" return c == '\\0';\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning) Char literal compared with pointer 'c'. Did you intend to dereference it?\n", errout.str());
check("bool foo(char* c) {\n"
" return '\\0' != c;\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning) Char literal compared with pointer 'c'. Did you intend to dereference it?\n", errout.str());
check("bool foo(char c) {\n"
" return c == '\\0';\n"
"}");
ASSERT_EQUALS("", errout.str());
check("bool foo(char c) {\n"
" return c == 0;\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(char* c) {\n"
" if(c == '\\0') bar();\n"
"}");
TODO_ASSERT_EQUALS("[test.cpp:2]: (warning) Char literal compared with pointer 'c'. Did you intend to dereference it?\n", "", errout.str());
}
void check_signOfUnsignedVariable(const char code[], bool inconclusive=false) {
// Clear the error buffer..
errout.str("");