errno.h: ESTRPIPE

[Ralf Corsepius]

Jeff Johnston wrote:
> Ralf Corsepius wrote:
>> Christopher Faylor wrote:
>>> On Mon, Mar 16, 2009 at 08:29:26AM +0100, Ralf Corsepius wrote:
>>>  
>>>> newlib should stay with well established standards and not be polluted
>>>> with underdocumented, proprietary extensions.
>>>>     
>>>
>>> Do you have any other irrational prejudices you'd like to share with us?
>> No, simply point me to an official (POSIX, IEEE, ANSII or similar) 
>> standard documenting ESTRPIPE.
>>
>> Ralf
>>
> Hi Ralf,
> 
> According to Posix Section 2.4 states:
> 
> "Implementations may support additional errors not listed in this 
> clause, but shall not generate a different error number from one 
> required  by this part of ISO/IEC 9945 for an error condition described 
> in this part of ISO/IEC 9945...."
> 
> Similarly under SUSV:
> 
> "Additional implementation-dependent error numbers may be defined in 
> <errno.h>"
Well, this only applies from an OS's POV, i.e. an OS has the liberty to 
add further errnos.

Newlib is in a special position wrt. this: It is not part of the OS 
(glibc is), it is used by the OS.

I.e. what you are saying effectively means: Cygwin dictates to newlib 
what other OS using newlib must support.

That's a serious problem.

> Finally, glibc contains a number of errno extensions and it includes 
> ESTRPIPE.   Newlib often adopts glibc extensions as requested in the
> interest of making it easier to port code to newlib.
My view is converse: newlib adopts everything, to make packages which 
rely on non-portable constructs workable, instead of encouraging 
developers to make those applications portable.

> That said, if RTEMS absolutely doesn't want any of these extensions 
> there are two alternatives.  1. Simply write a sys/errno.h file with 
> only standard-provided errno values.

Why should we do so? It's Cygwin who wishes to use extensions, RTEMS has 
no use for.

>  If only standard-provided errnos 
> plus RTEMS extensions are to be supported, this makes the most sense as 
> you don't really require a common file and it will likely rarely require 
> maintenance.  2. Add flag checks to sys/errno.h that segregate the 
> extensions and only remove them if the flag is defined (by default all 
> are provided).  For example,  __NO_ERRNO_EXTENSIONS__.
> 
> Seem reasonable?
I am not convinced: Why no #ifdef __CYGWIN__?

It's _Cygwin_, who wishes to add _its_ extended errnos - I think, I 
should add RTEMS's error codes to newlib. May-be you'll then understand 
why I am opposed to this ESTRIPE addition?

Ralf