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Merge pull request #50 from richq/strncmp 

Improved strncmp checks
 * strings are always the same
 * inconclusive: using sizeof(char *) as size parameter
This commit is contained in:
Daniel Marjamäki 2011-10-29 03:13:21 -07:00
parent 2b8da1241b 45d0709ed5
commit 8416768e03
3 changed files with 94 additions and 1 deletions
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56
lib/checkother.cpp
View File

@ -419,6 +419,37 @@ void CheckOther::sizeofForArrayParameterError(const Token *tok)
);
}
void CheckOther::checkSizeofForStrncmpSize()
{
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
const char pattern1[] = "strncmp ( %any , %any% , sizeof ( %var% ) )";
const char pattern2[] = "strncmp ( %any , %any% , sizeof %var% )";
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
if (Token::Match(tok, pattern1) || Token::Match(tok, pattern2)) {
int tokIdx = 7;
if (tok->tokAt(tokIdx)->str() == "(")
++tokIdx;
const Token *tokVar = tok->tokAt(tokIdx);
if (tokVar->varId() > 0) {
const Variable *var = symbolDatabase->getVariableFromVarId(tokVar->varId());
if (var && var->nameToken()->strAt(-1) == "*") {
sizeofForStrncmpError(tokVar);
}
}
}
}
}
void CheckOther::sizeofForStrncmpError(const Token *tok)
{
reportError(tok, Severity::warning, "strncmpLen",
"Passing sizeof(pointer) as the last argument to strncmp.\n"
"Passing a pointer to sizeof returns the size of the pointer, not "
"the number of characters pointed to by that pointer. This "
"means that only 4 or 8 (on 64-bit systems) characters are "
"compared, which is probably not what was expected.");
}
//---------------------------------------------------------------------------
// switch (x)
// {
@ -2253,8 +2284,9 @@ void CheckOther::checkAlwaysTrueOrFalseStringCompare()
if (!_settings->isEnabled("style") && !_settings->isEnabled("performance"))
return;
const char pattern1[] = "strcmp|stricmp|strcmpi|strcasecmp|wcscmp ( %str% , %str% )";
const char pattern1[] = "strncmp|strcmp|stricmp|strcmpi|strcasecmp|wcscmp ( %str% , %str% ";
const char pattern2[] = "QString :: compare ( %str% , %str% )";
const char pattern3[] = "strncmp|strcmp|stricmp|strcmpi|strcasecmp|wcscmp ( %var% , %var% ";
const Token *tok = _tokenizer->tokens();
while (tok && (tok = Token::findmatch(tok, pattern1)) != NULL) {
@ -2267,6 +2299,20 @@ void CheckOther::checkAlwaysTrueOrFalseStringCompare()
alwaysTrueFalseStringCompareError(tok, tok->strAt(4), tok->strAt(6));
tok = tok->tokAt(7);
}
if (!_settings->inconclusive)
return;
tok = _tokenizer->tokens();
while (tok && (tok = Token::findmatch(tok, pattern3)) != NULL) {
const Token *var1 = tok->tokAt(2);
const Token *var2 = tok->tokAt(4);
const std::string &str1 = var1->str();
const std::string &str2 = var2->str();
if (str1 == str2)
alwaysTrueStringVariableCompareError(tok, str1, str2);
tok = tok->tokAt(5);
}
}
void CheckOther::alwaysTrueFalseStringCompareError(const Token *tok, const std::string& str1, const std::string& str2)
@ -2289,6 +2335,14 @@ void CheckOther::alwaysTrueFalseStringCompareError(const Token *tok, const std::
}
}
void CheckOther::alwaysTrueStringVariableCompareError(const Token *tok, const std::string& str1, const std::string& str2)
{
reportError(tok, Severity::warning, "stringCompare",
"Comparison of identical string variables.\n"
"The compared strings, '" + str1 + "' and '" + str2 + "', are identical. "
"This could be a logic bug.");
}
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
void CheckOther::sizeofsizeof()

8
lib/checkother.h
View File

@ -58,6 +58,7 @@ public:
checkOther.checkRedundantAssignmentInSwitch();
checkOther.checkAssignmentInAssert();
checkOther.checkSizeofForArrayParameter();
checkOther.checkSizeofForStrncmpSize();
checkOther.checkSizeofForNumericParameter();
checkOther.checkSelfAssignment();
checkOther.checkDuplicateIf();
@ -196,6 +197,9 @@ public:
/** @brief %Check for using sizeof with array given as function argument */
void checkSizeofForArrayParameter();
/** @brief %Check for using sizeof with a char pointer */
void checkSizeofForStrncmpSize();
/** @brief %Check for using sizeof with numeric given as function argument */
void checkSizeofForNumericParameter();
@ -264,6 +268,7 @@ public:
void catchExceptionByValueError(const Token *tok);
void memsetZeroBytesError(const Token *tok, const std::string &varname);
void sizeofForArrayParameterError(const Token *tok);
void sizeofForStrncmpError(const Token *tok);
void sizeofForNumericParameterError(const Token *tok);
void incorrectStringCompareError(const Token *tok, const std::string& func, const std::string &string, const std::string &len);
void incorrectStringBooleanError(const Token *tok, const std::string& string);
@ -273,6 +278,7 @@ public:
void duplicateBranchError(const Token *tok1, const Token *tok2);
void duplicateExpressionError(const Token *tok1, const Token *tok2, const std::string &op);
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 duplicateBreakError(const Token *tok);
void assignBoolToPointerError(const Token *tok);
void unsignedLessThanZeroError(const Token *tok, const std::string &varname);
@ -293,6 +299,7 @@ public:
c.fflushOnInputStreamError(0, "stdin");
c.misusedScopeObjectError(NULL, "varname");
c.sizeofForArrayParameterError(0);
c.sizeofForStrncmpError(0);
c.sizeofForNumericParameterError(0);
c.coutCerrMisusageError(0, "cout");
@ -326,6 +333,7 @@ public:
c.duplicateBranchError(0, 0);
c.duplicateExpressionError(0, 0, "&&");
c.alwaysTrueFalseStringCompareError(0, "str1", "str2");
c.alwaysTrueStringVariableCompareError(0, "varname1", "varname2");
c.duplicateBreakError(0);
c.unsignedLessThanZeroError(0, "varname");
c.unsignedPositiveError(0, "varname");

31
test/testother.cpp
View File

@ -139,6 +139,7 @@ private:
TEST_CASE(duplicateExpression2); // ticket #2730
TEST_CASE(alwaysTrueFalseStringCompare);
TEST_CASE(checkStrncmpSizeof);
TEST_CASE(checkSignOfUnsignedVariable);
TEST_CASE(checkForSuspiciousSemicolon1);
@ -3418,6 +3419,36 @@ private:
" }"
"}");
ASSERT_EQUALS("", errout.str());
check_preprocess_suppress(
"int main()\n"
"{\n"
" if (strncmp(\"hotdog\",\"hotdog\", 6) == 0)"
" {"
" std::cout << \"Equal\n\""
" }"
"}");
ASSERT_EQUALS("[test.cpp:3]: (warning) Comparison of always identical static strings.\n", errout.str());
check_preprocess_suppress(
"int foo(const char *buf)\n"
"{\n"
" if (strcmp(buf, buf) == 0)"
" {"
" std::cout << \"Equal\n\""
" }"
"}");
ASSERT_EQUALS("[test.cpp:3]: (warning) Comparison of identical string variables.\n", errout.str());
}
void checkStrncmpSizeof() {
check(
"int fun(const char *buf1)\n"
"{\n"
" const char *buf1_ex = \"foobarbaz\";\n"
" return strncmp(buf1, buf1_ex, sizeof(buf1_ex)) == 0;\n"
"}");
ASSERT_EQUALS("[test.cpp:4]: (warning) Passing sizeof(pointer) as the last argument to strncmp.\n", errout.str());
}
void check_signOfUnsignedVariable(const char code[]) {