DeviceIoControl

DeviceIoControl Function: Sends a control code directly to a specified device driver, causing the corresponding device to perform the corresponding operation.

Serial: CRT debug report

Report type: _CRT_WARN, _CRT_ERROR, _CRT_ASSERT

Required Header: crtdbg.h

_CRT_WARN: Warnings, messages, and information that does not need immediate attention.
_CRT_ERROR: Errors, unrecoverable problems, and issues that require immediate attention.
_CRT_ASSERT: Assertion failures (asserted expressions that evaluate to FALSE).

Serial: DCB structure

DCB sructure detects the management settings for the serial port of the connection device.

The most critical phase in serial communications programming is configuring the port settings with the DCB structure.

Do not apply pointer arithmetic to pointers

Pointer arithmetic shall only be applied to pointers that address an array or array element (misra2004_17_1_PointerArithmeticOnNotPointers.rule)


Description:

"Pointer arithmetic shall only be applied to pointers that address an array or array element. Addition and subtraction of integers (including increment and decrement) from pointers that do not point to an array or array element results in undefined behaviour."

Benefits:

Rule makes the code more readable and less confusing.

Example:

void foo( int a[] ) {
   int* p1 = 0;
   int* p2;
   int* p3 = a;

   a++;     // OK
   p1++;    // Violation
   p2 = a;
   p2++;    // OK
   p3++;    // OK
}

Repair:

Do not apply pointer arithmetic to pointers.

References:
MISRA-C:2004 Guidelines for the use of the C language in critical systems

Chapter 6, Section 17
Author
ParaSoft


Tags: Pointer arithmetic, less confusing, more readable
 

switch shall have at least one case

Every switch statement shall have at least one case clause (misra2004_15_5_AvoidSwitchWithNoCase.rule)


Description

Every switch statement shall have at least one case.

Benefits:

Provides maintainability of 'switch' statement.

Example:

void foo(int i)
{

   switch(i)      /* Violation */
   {

       default:
           ;
   }

}

Repair:

void foo(int i)
{
   switch(i)      /* OK */
   {
     case 1:
     {

     }
     default:
           ;

   }

}

References:

MISRA-C:2004 Guidelines for the use of the C language in critical systems
Chapter 6, Section 15

Author
ParaSoft
 
 
 
Tags: switch, case, maintainability, Guidelines, critical systems
 
 

Do not convert pointer to pointer

A cast should not be performed between a pointer to object type and a different pointer to object type (misra2004_11_4_DoNotConvertPointerToPointer.rule)


Description:

"A cast should not be performed between a pointer to object type and a different pointer to object type. Conversions of this type may be invalid if the new pointer type requires a stricter alignment."

Note: This rule skips casting of void type.

Benefits:

Prevents incorrect pointer alignment.

Example:

void foo( ) {
   int* pi;
   char* i;

   i = (char*) pi; // Violation
   i = (char*) &i; // Violation
}

Repair:

Do not convert pointer to different pointer.

References:
MISRA-C:2004 Guidelines for the use of the C language in critical systems
Chapter 6, Section 11

Author
ParaSoft


Tags: cast, pointer, void, pointer alignment, MISRA, critical systems

Avoid using unsafe string functions

Avoid using unsafe string functions (UsageOfStringFunctions.rule)


Description

This rule detects code that uses unsafe string functions from C library.

Benefits:

Prevents the use of functions which may cause buffer overflows.

According to David A. Wheeler (see reference below), "C functions users must avoid using dangerous functions that do not check bounds unless they've ensured that the bounds will never get exceed.

Functions to avoid in most cases (or ensure protection) include the functions strcpy(), strcat(), sprintf() (with cousin vsprintf()), and gets().

These should be replaced with functions such as strncpy(), strncat(), snprintf(), fgets(), respectively."

Example:

#include
void main( void )
{
char* str1 = "testcase";
char* str2 = "testcase";
char* str3=0;

str3 = strcat( str1, str2 ); // Violation
}

Repair:

#include
void main( void )
{
char* str1 = "testcase";
char* str2 = "testcase";
char* str3=0;

str3 = strncat( str1, str2, 16 ); // OK
}

References:
http://www.dwheeler.com/secure-programs/Secure-Programs-HOWTO/dangers-c.html

Author
ParaSoft


Tags: Avoid, unsafe, string, function, unsafe string, C library, buffer overflows, dangerous functions, strncpy, strncat, snprintf, fgets

Modular programming in C

What is Modular programming ?

- A programming technique to break down program functions into separate modules/parts/layers.
- Module, have to accomplishes one function by containing the source codes and input/output variables needed to accomplish that function.

Do NOT check floats for equality

Don't check floats for equality; check for greater than or less than (EqualityFloatLeft.rule)


Description:
This rule checks whether you check floats for equality instead of checking for greater than or less than.

Benefits:

If you check floats for equality, you make your code more susceptible to rounding errors.

Example:

void func(float a, int b)
{
   if (a==b) { }     // Violation

   while (a!=b) { }  // Violation
}



Repair:

void func(float a, int b)
{
   if (a>=b) { }     // OK

   while (a<=b) { }  // OK
}

Author
ParaSoft


My comment for repairing:

void func(const float a, const int b)
{
    if ( a > b ) { }
    else if ( a < b ) {}
    else {}
    // while (a > b) { };
    // while (a < b) { };
}

Ref: http://www.c-faq.com/fp/fpequal.html
Tags: vav.vn, vav, float, float equality, check float values equality, floating point, absolute, epsilon

domain co.cc

http://www.zebrazone.co.cc/,
http://www.fansipan.co.cc/,
http://www.zebrazoo.co.cc/

altonjuve_shift_2_yahoo_dot_com

Avoid Directly Access Globals

Do not directly access global data from a constructor (AvoidDirectlyAccessGlobals.rule)


Description:

Directly accessing global data from a constructor is risky because the global object may not yet exist when the "other" static object is initialized. This rule detects if you directly access global data from a constructor.

Function call order

The value of an expression shall be the same under any order of evaluation that the standard permits (misra2004_12_2_4_FunctionsCallOrder.rule)


Description

"Apart from a few operators (notably the function call operator (), &&, , ?: and , (comma)) the order in which sub-expressions are evaluated is unspecified and can vary. This means that no reliance can be placed on the order of evaluation of sub-expressions, and in particular no reliance can be placed on the order in which side effects occur. Those points in the evaluation of an expression at which all previous side effects can be guaranteed to have taken place are called “sequence points”. Sequence points and side effects are described in sections 5.1.2.3, 6.3 and 6.6 of ISO 9899:1990 [2].

Note that the order of evaluation problem is not solved by the use of parentheses, as this is not a precedence issue." "Functions may have additional effects when they are called (e.g. modifying some global data). Dependence on order of evaluation could be avoided by invoking the function prior to the expression that uses it, making use of a temporary variable for the value.

Avoid indexing pointer

Array indexing shall be the only allowed form of pointer arithmetic (misra2004_17_4_AvoidIndexingPointerAsArray.rule)


Description:

"Array indexing is the only acceptable form of pointer arithmetic, because it is clearer and hence less error prone than pointer manipulation. This rule bans the explicit calculation of pointer values. Array indexing shall only be applied to objects defined as an array type. Any explicitly calculated pointer value has the potential to access unintended or invalid memory addresses. Pointers may go out of bounds of arrays or structures, or may even point to effectively arbitrary locations."

Drawbacks: For more complex code rule may not be able to check if there is indexed pointer which points to array. For such cases the rule may report false positives.

Dev-cpp: stray '\160' in program

The message "stray '\160' in program" when building by Dev-Cpp is occurred when using "Copy and Paste" action.

So, finally, DO NOT copy and paste source code. Please type line by line.

Avoid assignment in if

Avoid assignment in if statement condition (IfAssign.rule)


Description:

This rule checks whether your code has assignment within an if statement condition. This rule is enabled by default.

Benefits:

Legibility and maintainability.

Assignment in the context of an if statement is easily confused with equality.

Example:

void foo(int a, int b) {

  if ( a = b ) {}  // Violation

}

Repair:

void foo(int a, int b) {

  if ( a == b ) {} // OK
}

Author
ParaSoft

Avoid nested assignment statements

The value of an expression shall be the same under any order of evaluation that the standard permits (misra2004_12_2_5_AvoidNestedAssignment.rule)


Description

"Apart from a few operators (notably the function call operator (), &&, , ?: and , (comma)) the order in which sub-expressions are evaluated is unspecified and can vary. This means that no reliance can be placed on the order of evaluation of sub-expressions, and in particular no reliance can be placed on the order in which side effects occur. Those points in the evaluation of an expression at which all previous side effects can be guaranteed to have taken place are called “sequence points”. Sequence points and side effects are described in sections 5.1.2.3, 6.3 and 6.6 of ISO 9899:1990 [2].

Note that the order of evaluation problem is not solved by the use of parentheses, as this is not a precedence issue."

"Assignments nested within expressions cause additional side effects. The best way to avoid any chance of this leading to a dependence on order of evaluation is to not embed assignments within expressions.

For example, the following is not recommended:

x = y = y = z / 3;

x = y = y++;"

Benefits:

Rule prevents evaluation of expression dependent on compiler version.

Example:

void foo( int x, int y, int z ) {

   x = y = z / 3;  // Violation
}

Repair:

void foo( int x, int y, int z ) {
   y = z / 3;  // OK
   x = y;      // OK
}

References:

MISRA-C:2004 Guidelines for the use of the C language in critical systems

Chapter 6, Section 12

Author
ParaSoft

Struct vs Union

A structure is a collection of items of different types; and each data item will have its own memory location.

An union allocates for each item in a shared memory location i.e., only one memory location will be shared by the data items of union. Size of union will be the size of the biggest variable.

Do not reuse typedef names

Do not reuse typedef names (misra2004_5_3_DoNotReuseTypedefNames.rule)


Description

Typedef names shall not be reused.

Benefits:

Reuse of typedef names can lead to errors and confusion.

Example:

typedef int MyInt;
void foo()
{
 double MyInt;  /* Violation */
}

Repair:
typedef int MyInt;
void foo()
{
 double MyVar;  /* OK */
}

References:

MISRA-C:2004 Guidelines for the use of the C language in critical systems

Chapter 6, Section 5

Author
ParaSoft

Do not mix bit-fields

Do not mix bit-fields other data within the same structure (misra2004_3_5_BitFieldStructuresWithoutOtherData.rule)


Description

It is recommended that structures should be declared specifically to hold the sets of bit fields, and do not include any other data within the same structure.

Benefits:

Rule prevents from the potential pitfalls and areas of implementation-defined (i.e.non-portable) behaviour.

Example:

struct message {  /* Violation */
   signed int little: 4;
   unsigned int x_set: 1;

   int size;
};

Repair:

struct message {  /* OK */
   signed int little: 4;
   unsigned int x_set: 1;
};

References:

MISRA-C:2004 Guidelines for the use of the C language in critical systems

Chapter 6, Section 3

Author
ParaSoft

error information shall be tested

Violations:
misra2004-16_10: If a function returns error information, then that error information shall be tested

Description:

"A function (whether it is part of the standard library, a third party library or a user defined function) may provide some means of indicating the occurrence of an error. This may be via an error flag, some special return value or some other means. Whenever such a mechanism is provided by a function the calling program shall check for the indication of an error as soon as the function returns.

However, note that the checking of input values to functions is considered a more robust means of error prevention than trying to detect errors after the function has completed (see Rule 20.3). Note also that the use of errno (to return error information from functions) is clumsy and should be used with care (see Rule 20.5)."

Note:
Rules checks usage of function calls which returns int value and reports violation when this value is not assigned or checked.

Benefits:
Rule helps writing safety code.

Example:

int SomeFunctionReturningError( );

void foo( )  {
   SomeFunctionReturningError( );  // Violation
}

Repair:

int SomeFunctionReturningError( );

int foo( )  {

   int x;
   x = SomeFunctionReturningError( );        // OK
   if (SomeFunctionReturningError( ));       // OK

   switch (SomeFunctionReturningError( )) {  // OK

   }

   return SomeFunctionReturningError( );     // OK
}

References:
MISRA-C:2004 Guidelines for the use of the C language in critical systems

Chapter 6, Section 16

Author
ParaSoft