fd and bk in dlmalloc

Question

I was wondering if someone could clarify the following: if I'm not mistaken fd is a pointer to the next malloc_chunk structure in the bin but I've also seen it specified as a pointer to the fd field in the malloc_chunk structure. So does it point to the beginning of the malloc_chunk struct or the fd field in the struct?

Answer 1

It's type is a struct malloc_chunk *, so it should point to a malloc_chunk structure, the next one. If it pointed to the fd field, it would be a pointer to a pointer to a pointer, ...., which could be stored as a void *