Re: [Valgrind-users] Finding illegal memory accesses when Valgrind fails via an assertion

[Olly B. <ol...@su...>]

On Sat, Mar 31, 2007 at 12:35:42PM -0500, Stephen Torri wrote:
> Is this the correct us of VALGRIND_CHECK_MEM_IS_DEFINED? The macro wants
> a int and I am sending it the pointer to a const Component_Graph and a
> std::string.
> 
>     void Reverse_Impl::print_Graph
>     ( infrastructure::Component_Graph const& graph_ref,
>       std::string const name ) const

Incidentally, did you mean to pass name by reference here?

>     {
>         VALGRIND_CHECK_MEM_IS_DEFINED(&graph_ref,sizeof(graph_ref));

For the case of a variable, you can write that more simply as:

          VALGRIND_CHECK_VALUE_IS_DEFINED(graph_ref);

(which expands via a macro to essentially the same thing).

>         VALGRIND_CHECK_MEM_IS_DEFINED(&name,name.size());

That doesn't make sense - it checks "length of string" bytes from the
start of the string object.  But the std::string will probably
(inevitably I think actually) not hold the string data directly
but via a pointer or series of pointers.

So you can check the object:

         VALGRIND_CHECK_VALUE_IS_DEFINED(name);

And then the string contents:

         VALGRIND_CHECK_MEM_IS_DEFINED(name.data(), name.size());

Cheers,
    Olly