bwsalloc
ret = bwsalloc(s->len);
return (len == 0) ? bwsalloc(0) : NULL;
ret = bwsalloc(len);
ret = bwsalloc(len);
struct bwstring *bwsalloc(size_t sz);
ret = bwsalloc(sz);
ret = bwsalloc(0);