alt Hacker NewsHow do functions like alloca allocate memory from the stack?
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So what if several functions that use less than 4KB each call each other before using the stack variables in a way that the first access skips over one page?
Recommended related reading: https://nullprogram.com/blog/2024/02/05/
One thing that scares me a little is whether there are younger developers, say, 25-40, who can and want to pick up the mantle of Windows internals gurus.
I mean, Chen has decades of winternals in his head. Microsoft has been gutting their staff for years now. When the Petzold/Chen generation hang up their spurs, does Microsoft still have a critical mass of people who understand Windows from the metal up?
Only passingly related, some fun rust stack-allocation insanity by my 17yo son:
Related to the above, two important concepts to know w.r.t a stack are "Red Zone" and "Guard Pages".
Raymond Chen again;
Why do we even need to define a red zone? Can’t I just use my stack for anything? - https://devblogs.microsoft.com/oldnewthing/20190111-00/?p=10...
A closer look at the stack guard page - https://devblogs.microsoft.com/oldnewthing/20220203-00/?p=10...
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One of those functions that isn't really implementable in standard C, requiring either compiler support, or being written in straight Assembly for stack registers manipulation, one of those "micro runtime" features for C.
From UNIX 7th edition all the way up to C99, when VLAs where introduced, only to be made optional in C11, and the C23 update still doesn't support automatic VLAs, only for function parameters, thus the point stands.