Example: memset Wrapper Self-Checks

Example: memset Wrapper Self-Checks

Here's an example of what you can do in a wrapper function called “memset_wrapper” from one of the Aussie AI projects:

    void *memset_wrapper(void *dest, int val, int sz)  // Wrap memset
    {
        if (dest == NULL) {
                yassert2(dest != NULL, "memset null dest");
                return NULL;
        }
        if (sz < 0) {
                // Why we have "int sz" not "size_t sz" above
                yassert2(sz >= 0, "memset size negative");
                return dest;  // fail
        }
        if (sz == 0) {
                yassert2(sz != 0, "memset zero size (reorder params?)");
                return dest;
        }
        if (sz <= sizeof(void*)) {
                // Suspiciously small size
                yassert2(sz > sizeof(void*), "memset with sizeof array parameter?");
                // Allow it, keep going
        }
        if (val >= 256) {
                yassert2(val < 256, "memset value not char");
                return dest; // fail
        }
        void* sret = ::memset(dest, val, sz);  // Call real one!
        return sret;
    }

It's a judgement call whether or not to leave the debug wrappers in place, in the vein of speed versus safety. Do you prefer sprinting to make your flight, or arriving two hours early? Here's one way to remove the wrapper functions completely with the preprocessor if you've been manually changing them to the wrapper names:

    #if YDEBUG
        // Debug mode, leave wrappers..
    #else // Production (remove them all)
        #define memset_wrapper memset
        //... others
    #endif

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