Thanks for this!

        char* copy_c_str(const char* orig)
        {
                size_t len =  strlen(orig) + 1 ;             
                char* copy = (char*) malloc(sizeof(char) * len );
                memcpy(copy, orig, len);
                return copy;
        }

Anyway, please don't cast the return value of malloc() in C (http://stackoverflow.com/a/605858/28169).

Also, of course len should be const and sizeof (char) should be removed. Also testing whether malloc() succeeded before relying on the result being valid is a good idea (but perhaps there's machinery in place to abort on error), as is deciding what to do if the input string is NULL.

It's C++.

    return( strdup( orig ) );

?