指向呼叫者SAL错误的指针的输出

Question

I am trying to add SAL to my code... i worked according msdn and found bug in msdn examples, don't know how to deal with it.

Here litle changed example "Output of pointer to caller (Example: The Outptr Annotation)" from Understanding SAL

Outptr is used to annotate a parameter that's intended to return a pointer. The parameter itself should not be NULL, and the called function returns a non-NULL pointer in it and that pointer points to initialized data.

My code:

#include "stdafx.h"
#include "assert.h"

void GoodOutPtrCallee(_Outptr_ int **pInt)
{
    int *pInt2 = new int;

    if (*pInt != NULL)
    {
        *pInt2 = 1;
    }
    else
    {
        *pInt2 = 2;
    }

    *pInt = pInt2;
}

int _tmain(int argc, _TCHAR* argv[])
{
    int* nullValue = NULL;
    GoodOutPtrCallee(&nullValue); 
    assert(*nullValue == 2);

    int someValue = 22;
    int* someValuePtr = &someValue;
    GoodOutPtrCallee(&someValuePtr); 
    assert(*someValuePtr == 1);

    return 0;
}

If i compile it in VS2013 with code alalysys enabled i got C6001: using uninitialized memory

for

if (*pInt != NULL)

row.

What is worng here in my annotation and how can i fix it?

Answer 1

Since you're reading from the value passed through the pointer parameter pInt you can't use _Outptr_ , as this describes a parameter that's only used as an output, not also as an input. Use _Inout_ instead.

You might want to reconsider using SAL. It's very poorly documented, and as a result I can't say with any certainty that _Inout_ is actually the best annotation to use here. All I know for sure is that it's best match I could find based on Microsoft's vague descriptions, and it gets rid of the warning. Of course so would not using an annotation.

Answer 2

EDIT : I was confused by similar variable names, pInt and pInt2 . You're probably should mark pInt as input and output, not just as output, because you're reading it's value to check whether it is NULL