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From: Michael S <already5chosen@yahoo.com>
Newsgroups: comp.arch
Subject: Re: stack sizes, Segments
Date: Thu, 23 Jan 2025 01:45:16 +0200
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On Wed, 22 Jan 2025 15:01:34 GMT
scott@slp53.sl.home (Scott Lurndal) wrote:

> Michael S <already5chosen@yahoo.com> writes:
> >On Wed, 22 Jan 2025 02:54:33 -0000 (UTC)
> >John Levine <johnl@taugh.com> wrote:
> >  
> >> According to George Neuner  <gneuner2@comcast.net>:  
> >> >Not standard compliant for sure, but you certainly can approximate
> >> >stack use in C:  just store (as byte*) the address of a local in
> >> >your top level function, and check the (absolute value of) the
> >> >difference to the address of a local in the current function.    
> >> 
> >> Ugh, but yes that would work with the usual stack structure,
> >>   
> >> >The bigger problem is knowing how much stack is available to use -
> >> >there may be no way (or no easy way) to find the actual size ...
> >> >or the limit if the stack expands ... and circumstances beyond the
> >> >program may have limited it to be smaller than the program
> >> >requested.    
> >> 
> >> There's often no way to tell since it may depend on things like
> >> running out of swap space which depends on how much memory other
> >> programs are using.
> >>   
> >
> >At least you can know the size of reserved VA space which is both an
> >upper bound of the limit and in 99% of the cases an actual limit.
> >
> >On Windows:
> >https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-getcurrentthreadstacklimits
> >
> >I suppose that similar functions are available on other OSes as well.
> >  
> 
> https://pubs.opengroup.org/onlinepubs/9799919799/functions/pthread_attr_getstack.html
> 
> There is no equivlent function for the main process stack,


Do you mean "there is no equivlent *POSIX* function", right?
But I sincerily hope that most Unix-like systems provide such
functionality in system-specific manner. Because it looks usable.

> other than
> the 'getrlimit(RLIMIT_STACK...' functionality.