RE: [EXTERNAL] Re: Fw: Re: Fw: Re: Why do these mprotect always fail?

["Lavrentiev, Anton (NIH/NLM/NCBI) [C]" <lavr@ncbi.nlm.nih.gov>]

> I still think it's a bug in the code which requires some debugging effort
> on your side.

I think that OP does not understand that the page size constant is a property of the platform, and not something that can be redefined at will even though it's a macro.

> > #ifndef __CYGWIN__
> > #define PAGE_SIZE 4096
> > #endif

If anything, IMO the conditional should look like:

#ifndef PAGE_SIZE
#define PAGE_SIZE 4096
#endif

and only used after all necessary headers that might define PAGE_SIZE on a particular platform (or all platforms that the code is supposed to be run on), have been already included.

$.02

Anton Lavrentiev
Contractor NIH/NLM/NCBI

> -----Original Message-----
> From: Cygwin <cygwin-bounces+lavr=ncbi.nlm.nih.gov@cygwin.com> On Behalf Of Corinna
> Vinschen via Cygwin
> Sent: Wednesday, February 15, 2023 11:33 AM
> To: w6b7rk5yu4mt25v3 <w6b7rk5yu4mt25v3@protonmail.com>
> Cc: Corinna Vinschen <corinna-cygwin@cygwin.com>; cygwin@cygwin.com
> Subject: [EXTERNAL] Re: Fw: Re: Fw: Re: Why do these mprotect always fail?
> 
> On Feb 15 15:31, w6b7rk5yu4mt25v3 via Cygwin wrote:
> > I asked the developer of the interpreter. He said it's OK to use the PAGE_SIZE value
> different than 4096. So I used this dirty hack:
> >
> > #ifndef __CYGWIN__
> > #define PAGE_SIZE 4096
> > #endif
> >
> > This means on Cygwin it will use the default PAGE_SIZE defined on limits.h (I'm taking
> advantage of the naming conflict here so I don't have to rename PAGE_SIZE to JIT_PAGE_SIZE
> as suggested by the developer of the interpreter).
> >
> > The result is it's no longer error with "Unable to mprotect" but will
> > silently crashed without any error messages printed on the screen. So
> > after all, it's Cygwin's quirks here.
> 
> I still think it's a bug in the code which requires some debugging effort
> on your side.
> 
> Having said that, if it's actually a Cygwin bug and you want it fixed,
> please provide a *simple*, self-contained testcase in plain C, with a
> minimum of code to reproduce the issue, and which compiles OOTB.
> 
> 
> Corinna
> 
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