[cfe-commits] [PATCH] review request - strcmp checker

Lenny Maiorani lenny at Colorado.EDU
Mon Apr 11 12:25:24 PDT 2011

On 04/08/2011 05:37 PM, Ted Kremenek wrote:
> Hi Lenny,
> I understand the intent is to model comparing raw string literals, but I think the use of getCStringLiteral() discards too much information.  For example, I don't think the following will be handled correctly:
>    const char *s1 = "foobar";
>    const char *s2 = "bar";
>    return strcmp(&s1[3], s2);
> In order to model strcmp() properly, you will also need to take into account the offset within the string literal.
> Also, could you add a FIXME indicating that this logic only handles comparing string literals (albeit, it handles flow analysis)?  Conceptually, we could enhance this to also handle non-literals as well in a variety of ways.
Nice catch Ted!

In fact, I think the entire CString checker needs this. I just tested 
strlen and that didn't work in this case either:
     void strlen_with_offset(const char *x) {
       if (strlen(x) != 5)
       if (strlen(&x[2]) != 3)
         (void)*(char*)0; // no-warning

Is this patch ok to be committed in lieu of this change? The next task I 
will take on will be fixing the modeling of all the functions in the 
CString checker to accommodate for this oversight. It will probably be a 
small change, but pervasive throughout the checker.


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