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Re: [PATCH 0/4] Use AF_ALG in checksum utilities
From: |
Dmitry V. Levin |
Subject: |
Re: [PATCH 0/4] Use AF_ALG in checksum utilities |
Date: |
Tue, 24 Apr 2018 17:31:54 +0300 |
On Tue, Apr 24, 2018 at 03:28:51PM +0200, Bruno Haible wrote:
> Hi Matteo,
>
> > > * As you already noticed, we need to avoid build failures and runtime
> > > failures
> > > on platforms where this is not supported.
> > >
> >
> > I see "#ifdef __linux__" already in use in gnulibs, I assume this is
> > the preferred way.
>
> Not really. When being compiled on an older Linux machine, that does not have
> the
> necessary include files, this "#ifdef __linux__" would lead to a compilation
> error.
>
> Therefore the preferred way is to test for the essential header files. For
> example,
> suppose AF_ALG gets defined by <linux/foobar.h> and is present in every
> version of
> <linux/foobar.h> (even the oldest ones). Then in the Autoconf macro we would
> need
>
> AC_CHECK_HEADERS([linux/foobar.h])
>
> and in the code we would have
>
> #if HAVE_LINUX_FOOBAR_H
Just using the header that provides a prototype for socket(), most likely
#include <sys/socket.h>
and checking
#ifdef AF_ALG
should be enough in this case.
--
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