Reddit mentions of Mac OS X Internals: A Systems Approach

This might be a bit too deep for what you're looking for currently, but Jonathan Levin is actively writing a series of books on OS X Internals. Worth checking out and much more up to date than Amit Singh's book.

Mac OS X Internals: A Systems Approach by Amit Singh is the canonical guide. It focuses on how the operating system works, but that'll provide a lot of insight into how things work at the hardware level, too.

>My portion is on the Macintosh file system and security.

HFS+ needs to be taken out back and shot. ZFS was considered as a replacement until Sun's CEO shot off his mouth. It was also rumoured that licensing issues didn't help, either.


>1. I understand that Mac's don't have a registry. In windows, when a program installs there are registry entries and necessary parts of the program are installed into memory at startup. If there's no registry, then clearly this doesn't happen for OSX. Does this mean that each application is an effective island, with separate coding that doesn't affect the others?

Correct. Each app generally stores everything it needs inside its own app bundle (the folder which looks and acts like a file which is the app itself). On a Mac, right-click on an app and click Show Package Contents to have a peek behind the curtains.


>2. When you install the OS, the installer is essentially the first admin on the system who then has the power to create other admins. Can that user be removed by other members of the admin group? And how does that work for networks?

Yes, any admin user can delete any other user. If the network uses Open Directory for centralized signins, then the machine's local user account database isn't used.


>3. I know that MACs are relatively free of viruses, but it would seem to me that if I were trying to write a virus, the first thing that I would do is to attempt to activate the root user account. Are there any specific safeguards against that?

The root account is useless on a modern Mac; it requires user interaction to do so anyway. It's far easier to request permission to make a systemwide change (convincing the user to enter their password), since almost all users have administrative rights (protected by that same authorization dialog).


This book would likely give you everything you need to know. Need more gory details? This book would deliver those.

> For those who prefer video lectures, Skiena generously provides his online. We also really like Tim Roughgarden’s course, available from Stanford’s MOOC platform Lagunita, or on Coursera. Whether you prefer Skiena’s or Roughgarden’s lecture style will be a matter of personal preference.
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> For practice, our preferred approach is for students to solve problems on Leetcode. These tend to be interesting problems with decent accompanying solutions and discussions. They also help you test progress against questions that are commonly used in technical interviews at the more competitive software companies. We suggest solving around 100 random leetcode problems as part of your studies.
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> Finally, we strongly recommend How to Solve It as an excellent and unique guide to general problem solving; it’s as applicable to computer science as it is to mathematics.
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> [The Algorithm Design Manual](https://teachyourselfcs.com//skiena.jpg) [How to Solve It](https://teachyourselfcs.com//polya.jpg)> I have only one method that I recommend extensively—it’s called think before you write.
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> — Richard Hamming
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> ### Mathematics for Computer Science
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> In some ways, computer science is an overgrown branch of applied mathematics. While many software engineers try—and to varying degrees succeed—at ignoring this, we encourage you to embrace it with direct study. Doing so successfully will give you an enormous competitive advantage over those who don’t.
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> The most relevant area of math for CS is broadly called “discrete mathematics”, where “discrete” is the opposite of “continuous” and is loosely a collection of interesting applied math topics outside of calculus. Given the vague definition, it’s not meaningful to try to cover the entire breadth of “discrete mathematics”. A more realistic goal is to build a working understanding of logic, combinatorics and probability, set theory, graph theory, and a little of the number theory informing cryptography. Linear algebra is an additional worthwhile area of study, given its importance in computer graphics and machine learning.
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> Our suggested starting point for discrete mathematics is the set of lecture notes by László Lovász. Professor Lovász did a good job of making the content approachable and intuitive, so this serves as a better starting point than more formal texts.
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> For a more advanced treatment, we suggest Mathematics for Computer Science, the book-length lecture notes for the MIT course of the same name. That course’s video lectures are also freely available, and are our recommended video lectures for discrete math.
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> For linear algebra, we suggest starting with the Essence of linear algebra video series, followed by Gilbert Strang’s book and video lectures.
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> > If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is.
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> — John von Neumann
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> ### Operating Systems
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> Operating System Concepts (the “Dinosaur book”) and Modern Operating Systems are the “classic” books on operating systems. Both have attracted criticism for their writing styles, and for being the 1000-page-long type of textbook that gets bits bolted onto it every few years to encourage purchasing of the “latest edition”.
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> Operating Systems: Three Easy Pieces is a good alternative that’s freely available online. We particularly like the structure of the book and feel that the exercises are well worth doing.
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> After OSTEP, we encourage you to explore the design decisions of specific operating systems, through “{OS name} Internals” style books such as Lion's commentary on Unix, The Design and Implementation of the FreeBSD Operating System, and Mac OS X Internals.
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> A great way to consolidate your understanding of operating systems is to read the code of a small kernel and add features. A great choice is xv6, a port of Unix V6 to ANSI C and x86 maintained for a course at MIT. OSTEP has an appendix of potential xv6 labs full of great ideas for potential projects.
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> [Operating Systems: Three Easy Pieces](https://teachyourselfcs.com//ostep.jpeg)
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> ### Computer Networking
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> Given that so much of software engineering is on web servers and clients, one of the most immediately valuable areas of computer science is computer networking. Our self-taught students who methodically study networking find that they finally understand terms, concepts and protocols they’d been surrounded by for years.
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> Our favorite book on the topic is Computer Networking: A Top-Down Approach. The small projects and exercises in the book are well worth doing, and we particularly like the “Wireshark labs”, which they have generously provided online.
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> For those who prefer video lectures, we suggest Stanford’s Introduction to Computer Networking course available on their MOOC platform Lagunita.
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> The study of networking benefits more from projects than it does from small exercises. Some possible projects are: an HTTP server, a UDP-based chat app, a mini TCP stack, a proxy or load balancer, and a distributed hash table.
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> > You can’t gaze in the crystal ball and see the future. What the Internet is going to be in the future is what society makes it.
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> — Bob Kahn
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> [Computer Networking: A Top-Down Approach](https://teachyourselfcs.com//top-down.jpg)
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> ### Databases
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> It takes more work to self-learn about database systems than it does with most other topics. It’s a relatively new (i.e. post 1970s) field of study with strong commercial incentives for ideas to stay behind closed doors. Additionally, many potentially excellent textbook authors have preferred to join or start companies instead.
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> Given the circumstances, we encourage self-learners to generally avoid textbooks and start with the Spring 2015 recording of CS 186, Joe Hellerstein’s databases course at Berkeley, and to progress to reading papers after.
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> One paper particularly worth mentioning for new students is “Architecture of a Database System”, which uniquely provides a high-level view of how relational database management systems (RDBMS) work. This will serve as a useful skeleton for further study.
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> Readings in Database Systems, better known as the databases “Red Book”, is a collection of papers compiled and edited by Peter Bailis, Joe Hellerstein and Michael Stonebreaker. For those who have progressed beyond the level of the CS 186 content, the Red Book should be your next stop.
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> If you insist on using an introductory textbook, we suggest Database Management Systems by Ramakrishnan and Gehrke. For more advanced students, Jim Gray’s classic Transaction Processing: Concepts and Techniques is worthwhile, but we don’t encourage using this as a first resource.
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Depends how good you are at C++.

Mac OS X Internals: a systems approach
Chapter 10

http://www.amazon.com/Mac-OS-Internals-Systems-Approach/dp/0321278542/

Or this tutorial/writeup:
http://wagerlabs.com/writing-a-mac-osx-usb-device-driver-that-impl

For starting, you can read John Siracusa's many articles on OS X at Ars Technica. They are both informative and entertaining and stay at a pretty high level.

To get more in depth and really in the weeds, there's this.

> HFS+ definitely still gets fragmented to hell. The OS since 10.4 defragments important files, but large hard drives can get very fragmented.

This is actually a pretty interesting subject. If you've ever read Mac OS X Internals: A Systems Approach, Singh covers it very well.