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SubjectRe: Use enum to declare errno values
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On Wed, 23 Nov 2005, Denis Vlasenko wrote:

> On Wednesday 23 November 2005 16:19, linux-os (Dick Johnson) wrote:
>>> I'm just wondering why not declaring errno values using enumaration ?
>>> It is just more convenient when debuging the kernel.
>>>
>>> Thanks
>>
>> There is an attempt to keep kernel errno values similar to
>> user-mode errno values. This simplifies the user-kernel
>> interface where the kernel will return -ERRNO and the user-mode
>> code negates it and puts it into the user errno then sets the
>> return value to -1 (a Unix convention).
>>
>> The user-mode errno's therefore must correspond. You can't
>> expect the 'C' runtime libraries to be rebuilt and/or all the
>> programs recompiled just because the kernel got changed so
>> the errno's are hard-coded. 0 will always mean "no error" and
>> 1 will always be EPERM, etc. There are error-codes that are
>> the same number also, EWOULDBLOCK and EAGAIN are examples.
>>
>> So, you can't just auto-enumerate. If auto-enumeration isn't
>> possible, then you might just as well use #define, which is
>> what is done.
>
> ?!!
>
> enum {
> one,
> two,
> ten = 10
> };
>
> --

Did you BOTHER to read or you just picking a fight??

Cheers,
Dick Johnson
Penguin : Linux version 2.6.13.4 on an i686 machine (5589.55 BogoMips).
Warning : 98.36% of all statistics are fiction.
.

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