EPISODE 5 - Scott and Mark Learn To... Undocumented APIs

In this episode of Scott and Mark Learn To, Scott Hanselman and Mark Russinovich delve into the intricate world of undocumented APIs, examining their associated risks and benefits. Mark shares his journey into reverse engineering, starting with the Apple II and evolving through his exploration of Windows internals. He elaborates on his PhD thesis on fault management, which sparked his interest in undocumented APIs. The conversation includes technical insights into disassembling and debugging, showcasing Mark’s development of his own disassembler and use of tools like SoftICE for kernel debugging. They also explore Microsoft’s rationale for keeping certain APIs undocumented, highlighting the importance of flexibility in system evolution without compromising application stability.

Code: Q4TI1OFEYGXPXQSB

[JoNo-ly]

Old SoftIce dev here. Thanks for the shout out ;). Those were good times.

Good stuff! Matt Rickard said: "With a sufficient number of users of an API, it does not matter what you promise in the contract: all observable behaviors of your system will be depended on by somebody."

[haukurorsson]

I like how the progress bar on the on-screen media player videos matches the progress on the actual youtube video :)

[eryxjose]

Good to know how things evolved in Windows world. Always great to see you both on the show Scott and Mark. Wonder if you can bring more about AI. Maybe future features or good use cases. Thank you both for always share great contents.

[burndasbr]

17:03 To this day Microsoft has not documented how to properly detect dark mode. In their documentation they just recommend to check if the "perceived brightness" text color is "light", which is just an even bigger hack than just using the undocumented APIs or registry keys.

[nothingisreal]

Mark is right: app compatibility is the reason why Windows is so popular. But as much as it is a blessing for both MS and the customers it is also a curse. Looking at Windows 11 MS has failed to completely remove something like Microsoft Management Console or Control Panel. It just doesn't break. That makes Windows appearance "clunky" compared to competitors like MacOS or the shiny UX you see on modern smart phones or even on many web sites.
The lack of being capable to adapt to new concepts, without breaking old stuff, is the reason why Linux never got popular on the Desktop. Something as simple as using directory names that contain spaces breaks many Linux based apps. Tabs vs. spaces - still a discussion. System wide proxy configuration - not available.

[JohnTarbox]

It has been reported, although I do not know if it is true, that the Excel team for the first Windows version (Excel 2.0, I believe) used an undocumented memory management API to make the product faster than what competitors could do using only documented Windows APIs. Some claimed that Microsoft thus gained an "unfair" advantage for its applications.

Have you heard this and are you able to comment on this (ahem) rumor?

[pratikgiri]

Hi Scott, can you please tell me your VScode theme?

[crmster]

Saw some old school Russian hackers showing off those same books on LinkedIn once, must have been handy tools of the trade.

[UmmarFarooqMahroof]

Just out of curiosity since Scott bought out the games box, I wonder how many of the MS bigwigs like Mark et al play or played video games and which games they played. I always assumed the reason they are soo successful because they DIDN'T play video games after like 20 years old. Also in the spirit of learning then, Video games !!!!, direct X and stuff

[TheStevenWhiting]

I agree. With all stupid moves Microsoft are currently doing especially with Recall. But they don't get enough credit of allowing old apps to run. Apple don't care and kill them. I disagree with Mark. You have factories that rely on old software to run their old machines. Nothing wrong with that, not every business can afford to update all their machinery. The NHS pathology department has locked off, air gapped Windows XP machined because all the software works. No one wants to pay for yearly subs.

[alxr]

I didn’t know Tony Hawk was such an accomplished programmer.

[mattcargile]

Release the procexp undocumented apis! 😂 Haven’t watched the video fully yet.

[TheStevenWhiting]

How much code now does Microsoft rob from small developers? That last bit was quite interesting.

[Rayburn]

Seriously though, I wish 16-bit applications were supported again. "Move on" is such a discouraging response.

[kc]

"This video is sponsored by L'Oreal hair dye." 😉😄

[hero]

I assume Mark is easy 50+ with zero grays or dye?

[Steve-Richter]

I found Mark's sys internals books pretty disappointing. He had all of those wonderful tools. But provided no source code that I can remember. And the books were focused on using the utilities, rather than explaining how they worked.