Let's Write a Malloc

I semi-recently implemented a malloc tester (am TAing an OS course). Students write their own implementation of malloc and free, and then I "intercept" their calls to brk and sbrk by using macros to re-define those symbols as my own versions of those functions. It is quite nice: I have knobs to "fuzz" the alignment of returned addresses from sbrk, as well as to inject arbitrary EAGAINs, to see if they're following the man pages. Another thing that I looked…

There are so many complaints here about how simplistic this is and how it is nowhere near what a "good" malloc does. That's kind of the point. Let's implement the most brain-dead version of this code. This is code you can quickly understand and reason about. It gives you a baseline to understand all the improvements that are included in a "real" malloc. It would have been nice to include a list of the types of changes that a modern…