Re: [Chicken-users] Sendfile error on Red Hat 5.5 64 Bit

[David Krentzlin]

Good evening Vok,

On 01.12.2011 18:36, Vok Vojwo wrote:
> But I found a difference between my 32 Bit and 64 Bit system. On the
> 32 Bit system I have two definitions:
>
> $ find /usr/include/ -type f | xargs grep POSIX_FADV_SEQUENTIAL
> /usr/include/linux/fadvise.h:#define POSIX_FADV_SEQUENTIAL      2 /*
> Expect sequential page references.  */
> /usr/include/bits/fcntl.h:# define POSIX_FADV_SEQUENTIAL        2 /*
> Expect sequential page references.  */
>
> And on the 64 Bit system I have only one:
>
> # find /usr/include/ -type f | xargs grep POSIX_FADV_SEQUENTIAL
> /usr/include/bits/fcntl.h:# define POSIX_FADV_SEQUENTIAL        2 /*
> Expect sequential page references.  */
>
> The file is part of the kernel headers:
> $ rpm -qf /usr/include/linux/fadvise.h
> kernel-headers-2.6.18-194.8.1.el5

The definition resides in /usr/include/bit/fcntl.h which is present on 
both systems. This file is referenced by fcntl.h. And from what you 
wrote, it also includes the POSIX_FADV_SEQUENTIAL constant.

The question is, why isn't it visible to the sendfile code?
I have found that the probing code adds a _XOPEN_SOURCE definition 
whereas the actual implementation did not.
I'm still quite confident that this is the culprit, but i don't know yet 
how to tackle it correctly. My current guess is that the definition is 
too late in the code to actually have an effect, as the header file has 
already been loaded.


> But the main problem seems to me that the probe works and the
> compilation does not. So the probe includes something different than
> the compilation. I did not try if the installation of the kernel
> headers fixes the problem, because right now I do not know if I am
> allowed to do it on the production system. But the difference between
> the probe and the compilation is still a bug I think.

Yes, that is a bug in the setup-code.
I moved the definition to the very top of the source-file so that the 
only header that comes before that definition is chicken.h.

This is the only difference between the probing code and the actual 
implementation.

Could you please try again the current tip and tell me if it changed?
Also if it didn't change, could you please include your chicken.h in the 
probing code and see if it still gets selected?


Thanks
David