[paavoova]

> The caller might turn the element after the (struct header_t ) into something else

Isn't this exactly the issue with this malloc implementation? The pointer returned that points past the header by sizeof(header) may not be aligned for subsequent types.

[simcop2387]

This is a problem inherit to all malloc() implementations, since it never gets any type information it can't ever make any adjustments about alignment of the final type that's involved. I'm not actually sure what the fully correct way to ensure that would be.