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Fix some FNs related to c_str() (#4258)

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chrchr-github 2022-07-10 11:38:01 +02:00 committed by GitHub
parent f5c4a21eae
commit c218859418
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3 changed files with 58 additions and 0 deletions
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27
lib/checkstl.cpp
View File

@ -1953,6 +1953,9 @@ void CheckStl::string_c_str()
const Variable* var = tok->variable();
if (var->isPointer())
string_c_strError(tok);
} else if (printPerformance && Token::Match(tok->tokAt(2), "%var% . c_str|data ( ) ;")) {
if (tok->variable()->isStlStringType() && tok->tokAt(2)->variable()->isStlStringType())
string_c_strAssignment(tok);
}
} else if (printPerformance && tok->function() && Token::Match(tok, "%name% ( !!)") && tok->str() != scope.className) {
const std::pair<std::multimap<const Function*, int>::const_iterator, std::multimap<const Function*, int>::const_iterator> range = c_strFuncParam.equal_range(tok->function());
@ -1986,6 +1989,12 @@ void CheckStl::string_c_str()
}
}
} else if (printPerformance && Token::Match(tok, "%var% (|{ %var% . c_str|data ( )") && tok->variable()->isStlStringType() && tok->tokAt(2)->variable()->isStlStringType()) {
string_c_strConstructor(tok);
} else if (printPerformance && tok->next() && tok->next()->variable() && tok->next()->variable()->isStlStringType() && tok->valueType() && tok->valueType()->type == ValueType::CONTAINER &&
((Token::Match(tok->previous(), "%var% + %var% . c_str|data ( )") && tok->previous()->variable()->isStlStringType()) ||
(Token::Match(tok->tokAt(-5), "%var% . c_str|data ( ) + %var%") && tok->tokAt(-5)->variable()->isStlStringType()))) {
string_c_strConcat(tok);
}
// Using c_str() to get the return value is only dangerous if the function returns a char*
@ -2093,6 +2102,24 @@ void CheckStl::string_c_strParam(const Token* tok, nonneg int number)
reportError(tok, Severity::performance, "stlcstrParam", oss.str(), CWE704, Certainty::normal);
}
void CheckStl::string_c_strConstructor(const Token* tok)
{
std::string msg = "Constructing a std::string from the result of c_str() is slow and redundant.\nSolve that by directly passing the string.";
reportError(tok, Severity::performance, "stlcstrConstructor", msg, CWE704, Certainty::normal);
}
void CheckStl::string_c_strAssignment(const Token* tok)
{
std::string msg = "Assigning the result of c_str() to a std::string is slow and redundant.\nSolve that by directly assigning the string.";
reportError(tok, Severity::performance, "stlcstrAssignment", msg, CWE704, Certainty::normal);
}
void CheckStl::string_c_strConcat(const Token* tok)
{
std::string msg = "Concatenating the result of c_str() and a std::string is slow and redundant.\nSolve that by directly concatenating the strings.";
reportError(tok, Severity::performance, "stlcstrConcat", msg, CWE704, Certainty::normal);
}
//---------------------------------------------------------------------------
//
//---------------------------------------------------------------------------

3
lib/checkstl.h
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@ -193,6 +193,9 @@ private:
void string_c_strError(const Token* tok);
void string_c_strReturn(const Token* tok);
void string_c_strParam(const Token* tok, nonneg int number);
void string_c_strConstructor(const Token* tok);
void string_c_strAssignment(const Token* tok);
void string_c_strConcat(const Token* tok);
void outOfBoundsError(const Token *tok, const std::string &containerName, const ValueFlow::Value *containerSize, const std::string &index, const ValueFlow::Value *indexValue);
void outOfBoundsIndexExpressionError(const Token *tok, const Token *index);

28
test/teststl.cpp
View File

@ -4015,6 +4015,34 @@ private:
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("std::string f(const std::string& a) {\n"
" std::string b(a.c_str());\n"
" return b;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (performance) Constructing a std::string from the result of c_str() is slow and redundant.\n", errout.str());
check("std::string f(const std::string& a) {\n"
" std::string b{ a.c_str() };\n"
" return b;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (performance) Constructing a std::string from the result of c_str() is slow and redundant.\n", errout.str());
check("std::string f(const std::string& a) {\n"
" std::string b = a.c_str();\n"
" return b;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (performance) Assigning the result of c_str() to a std::string is slow and redundant.\n", errout.str());
check("std::string g(const std::string& a, const std::string& b) {\n"
" return a + b.c_str();\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (performance) Concatenating the result of c_str() and a std::string is slow and redundant.\n", errout.str());
check("std::string g(const std::string& a, const std::string& b) {\n"
" return a.c_str() + b;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (performance) Concatenating the result of c_str() and a std::string is slow and redundant.\n", errout.str());
}
void uselessCalls() {