Re: errnos.h usage

[Basile Starynkevitch <basile@starynkevitch.net>]

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Hello from near Paris in France,

On 2/14/24 05:59, Lucas Augusto Valentim Dantas via Libc-help wrote:
> Hello, I have been playing around with Doom's source code, the 90s one, and I have noticed that it has a header included named errnos.h that I have recently learned that it was actually present in glibc beginning from 2.0.0 (I think) until 2.0.7. Could anyone shed light on why it was added to glibc and later removed?
I can't explain why it was added. I can guess why it was removed.
>
> https://sources.debian.org/src/glibc/2.0.7t-1/sysdeps/unix/sysv/linux/errnos.h/
> https://github.com/id-Software/DOOM/blob/master/linuxdoom-1.10/i_video.c#L49


Maybe because errnos.h is no more in standard C or in POSIX. But errno.h 
is standard. See also https://man7.org/linux/man-pages/man3/errno.3.html
<https://man7.org/linux/man-pages/man3/errno.3.html>>

and https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf or buy 
from your ISO representative <https://www.iso.org/standard/74528.html> 
the formal C standard book.


 From my human (and perhaps wrong) memory, errnos.h existed on old 
operating systems and computers like Sun4/110 workstation with a 
SunOS3.5 (this was in the early 1990s, I worked then as a software 
developer at CEA <https://www.cea.fr/>). I don't have that header file 
on my current Debian/Sid/amd64 desktop.

Today, using errno actually requires the #include <errno.h> preprocessor 
directive, and on my Linux system it is a macro defined in 
/usr/include/errno.h as

> rimski.x86_64 ~/misc-basile 8:45 .0 %grep  errno_/usr/include/errno.h_  
>   *	ISO C99 Standard: 7.5 Errors	<errno.h>
> #include <bits/errno.h>
> extern int *__errno_location (void) __THROW __attribute_const__;
> # define errno (*__errno_location ())
> #endif /* errno.h */

And today my pet open source project is the RefPerSys 
<http://refpersys.org/> inference engine (*REF*lective *PER*sistent 
*SYS*tem, GPLv3+ licensed) on https://github.com/RefPerSys/RefPerSys/ ; 
if you know someone who wants to contribute, please forward to him/her 
this email.

Thanks for reading.

Regards

<https://man7.org/linux/man-pages/man3/errno.3.html>>

-- 
Basile Starynkevitch<basile@starynkevitch.net>
(only mine opinions / les opinions sont miennes uniquement)
92340 Bourg-la-Reine, France
web page: starynkevitch.net/Basile/
See/voir:https://github.com/RefPerSys/RefPerSys