C++代码静态分析工具-Prefast

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1. 什么是Prefast

Prefast是一种代码分析工具，它能够帮助你找到编译器不能找到的错误或者缺陷。Prefast首次被微软集成到Visual Studio 2005 Team Suite中去，使用起来非常方便。

2.怎么使用Prefast
在vs2005 Team Suite中，使用Prefast非常简单。修改你的工程属性，设置Enable Code Analysis For C/C++为Yes.

效果:

注意到有可能错误的地方以浅灰色显示在编辑器中了。

3.Prefast能帮你找到哪些错误

1)没有初始化

// no initial
void defect1()
{
         int a;
         int b;

        b = a;
}

会报: d:/test/testcode/testcode.cpp(18) : warning C6001: Using uninitialized memory 'a': Lines: 15, 16, 18

2)空指针取值

// one path dereference NULL
void defect4( int b, int c)
{
         int * p = NULL;
         int a = 1 ;

         if (b == 1 ) {
                 if (c == 1 ) {
                        p = & a;
                }
                 else {

                }
        }
         else {
                 if (c == 1 ) {

                }
                 else {
                        p = & a;
                }
        }

         * p;

         return ;
}

会报:d:/test/testcode/testcode.cpp(65) : warning C6011: Dereferencing NULL pointer 'p': Lines: 45, 46, 48, 57, 65

3)可能错误的运算符优先级

void defect5()
{
         int a = 1 ;
         int b = 1 ;
         int c = 1 ;

         if (a & b == c)
                 return ;
}

会报: d:/test/testcode/testcode.cpp(76) : warning C6281: Incorrect order of operations: relational operators have higher precedence than bitwise operators

4)可能的buffer overrun

void defect8()
{
         char buf[ 100 ];
         char buf2[ 200 ];
         int i = 100 ;

        sprintf(buf, " hello world %d " , i);
        strcpy(buf, buf2);
}

会报: d:/test/testcode/testcode.cpp(133) : warning C6202: Buffer overrun for 'buf', which is possibly stack allocated, in call to 'strcpy': length '200' exceeds buffer size '100'

5)可能的无穷循环

// infinite loop
void defect14()
{
        signed char i;

         for (i = 100 ; i >= 0 ; i ++ ) {
                ;
        }
}

会报: d:/test/testcode/testcode.cpp(198) : warning C6292: Ill-defined for-loop: counts up from maximum

6)格式字符串错误

// Format string mismatch
void defect21()
{
char buff[ 5 ];
sprintf(buff, " %s %s " , " a " );
}

会报: d:/test/testcode/testcode.cpp(277) : warning C6063: Missing string argument to 'sprintf' that corresponds to conversion specifier '2'

7)安全问题

void defect27()
{
        CreateProcess(NULL,
                " c://program files//Project.exe arg1 " , // correct "/"c://program files//Project.exe/" arg1",
               NULL,
               NULL,
                false ,
                0 ,
               NULL,
               NULL,
               NULL,
               NULL);
}

会报: d:/test/testcode/testcode.cpp(327) : warning C6277: NULL application name with an unquoted path in call to 'CreateProcessA': results in a security vulnerability if the path contains spaces

8)=和==误用

void defect32()
{
         int a = 1 ;

         if (a = 2 )
                 return ;
}

会报: d:/test/testcode/testcode.cpp(405) : warning C6282: Incorrect operator: assignment of constant in Boolean context. Consider using '==' instead

9)逻辑运算问题

// always false
void defect45()
{
         int x;

         if ( 0 && x ++ ) {
                ;
        }
}

会报: d:/test/testcode/testcode.cpp(564) : warning C6237: (<zero> && <expression>) is always zero. <expression> is never evaluated and might have side effects

10)其他