Better buffer-overrun prevention

    template <> // static

    status_t extract(std::string *val, const char **bufferpptr, const char *bufferptrmax) {

        const char *ptr = *bufferpptr;

        while (*ptr != 0) {

        do {

            if (ptr >= bufferptrmax) {

                ALOGE("%s: buffer exceeded", __func__);

                return BAD_VALUE;

            }

            ++ptr;

        }

        const size_t size = (ptr - *bufferpptr) + 1;

        } while (*ptr++ != 0);

        // ptr is terminator+1, == bufferptrmax if we finished entire buffer

        *val = *bufferpptr;

        *bufferpptr += size;

        *bufferpptr = ptr;

        return NO_ERROR;

    }

    template <> // static