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C

C static code analysis

Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code

  • All rules 315
  • Vulnerability13
  • Bug76
  • Security Hotspot19
  • Code Smell207

  • Quick Fix 19
Filtered: 37 rules found
suspicious
    Impact
      Clean code attribute
        1. "offsetof" macro should not be used

           Code Smell
        2. "errno" should not be used

           Code Smell
        3. Function names should be used either as a call with a parameter list or with the "&" operator

           Code Smell
        4. "enum" values should not be used as operands to built-in operators other than [ ], =, ==, !=, unary &, and the relational operators <, <=, >, >=

           Code Smell
        5. "bool" expressions should not be used as operands to built-in operators other than =, &&, ||, !, ==, !=, unary &, and the conditional operator

           Code Smell
        6. A cast shall not remove any const or volatile qualification from the type of a pointer or reference

           Code Smell
        7. Trigraphs should not be used

           Code Smell
        8. "#pragma pack" should be used correctly

           Bug
        9. Only valid arguments should be passed to UNIX/POSIX functions

           Code Smell
        10. Only valid arguments should be passed to stream functions

           Code Smell
        11. "^" should not be confused with exponentiation

           Code Smell
        12. Size of variable length arrays should be greater than zero

           Code Smell
        13. "mktemp" family of functions templates should have at least six trailing "X"s

           Code Smell
        14. Unevaluated operands should not have side effects

           Code Smell
        15. Size argument of memory functions should be consistent

           Code Smell
        16. Return value of "nodiscard" functions should not be ignored

           Code Smell
        17. Implicit casts should not lower precision

           Code Smell
        18. Appropriate size arguments should be passed to "strncat" and "strlcpy"

           Code Smell
        19. User-defined types should not be passed as variadic arguments

           Bug
        20. Array values should not be replaced unconditionally

           Bug
        21. A conditionally executed single line should be denoted by indentation

           Code Smell
        22. Conditionals should start on new lines

           Code Smell
        23. "case" ranges should cover multiple values

           Code Smell
        24. "switch" statements should cover all cases

           Code Smell
        25. Redundant pointer operator sequences should be removed

           Code Smell
        26. Conditionally executed code should be reachable

           Bug
        27. Flexible array members should not be declared

           Code Smell
        28. Track parsing failures

           Code Smell
        29. Recursion should not be infinite

           Bug
        30. Two branches in a conditional structure should not have exactly the same implementation

           Code Smell
        31. Pre-defined macros should not be defined, redefined or undefined

           Code Smell
        32. Switch cases should end with an unconditional "break" statement

           Code Smell
        33. "switch" statements should not contain non-case labels

           Code Smell
        34. Methods should not be empty

           Code Smell
        35. Assignments should not be made from within conditions

           Code Smell
        36. Variables should not be shadowed

           Code Smell
        37. Nested blocks of code should not be left empty

           Code Smell

        User-defined types should not be passed as variadic arguments

        intentionality - complete
        reliability
        Bug
        • suspicious
        • based-on-misra
        • cppcoreguidelines
        • cert

        Why is this an issue?

        More Info

        Variadic arguments allow a function to accept any number of arguments (in this rule, we are not talking about variadic templates, but about functions with ellipses). But these arguments have to respect some criteria to be handled properly.

        The standard imposes some requirements on the class types that can be passed as variadic arguments, and those requirements vary according to the C++ standard version in use:

        • Before C++11, the standard only allows POD types to be used as variadic arguments.
        • In C++11, the rules are relaxed such that any class type with an eligible non-trivial copy constructor, an eligible non-trivial move constructor, or a non-trivial destructor can be used in variadic arguments.

        The rule detects any violations of these requirements since they can trigger undefined behavior.

        Additionally, since using an incorrect type to access the passed parameter within the variadic function can lead to undefined behavior, the rule goes a step further and reports all cases when class types are passed as variadic arguments. The rationale is that, most likely, the user forgot to call a method on the object being passed (std::string_view::data() for example) that would get a member of a built-in type.

        When in need to pass class types to functions that take a variable number of arguments, consider using modern type-safe alternatives like C++11 parameter packs instead of variadic functions.

        Noncompliant code example

        void my_log(const char* format, ...);
        
        void f() {
          std::string someStr = "foo";
          my_log("%s", someStr);  // Noncompliant; the C++11 standard requires types passed as variadic arguments to have a trivial copy constructor. The user probably meant to pass someStr.c_str() here
        
          std::string_view someStrView = "bar";
          my_log("%s", someStrView); // Noncompliant; the user probably meant to pass someText.data()
          std::chrono::duration<float> duration;
          my_log("%f", duration); // Noncompliant, the user probably meant to pass duration.count()
        }
        

        Compliant solution

        void my_log(const char* format, ...);
        
        void f() {
          std::string someStr = "foo";
          my_log("%s", someStr.c_str());  // Compliant
        
          std::string_view someStrView = "bar";
          my_log("%s", someStrView.data()); // Compliant
          std::chrono::duration<float> duration;
          my_log("%f", duration.count()); // Compliant
        }
        

        Exceptions

        The rule doesn’t report an issue in the following cases:

        • When the called variadic function doesn’t have any non-variadic parameters. This is a common pattern when the function is used as a catch-all net for an overload set. This is also guaranteed to be safe since there is no portable to access the passed arguments.
        • When the called variadic function is known to accept a class type object as a variadic argument (e.g., the semctl system call).
        // This variadic function is used as a catch-all net to terminate recursion
        std::size_t elementsCount(...) { return 1u; }
        
        template<typename T>
        std::size_t elementsCount(const std::vector<T>& vec) {
          // Sum the elements of all nested vectors recursively
          return std::accumulate(vec.begin(), vec.end(), 0u, [] (const std::size_t count, const T& element) {
            return count + elementsCount(element); // Compliant (the callee doesn't have non-variadic arguments)
          });
        }
        
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