Re: Redefinition of struct in6_addr in <netinet/in.h> and <linux/in6.h>

From: Mike Frysinger
Date: Wed Jan 16 2013 - 12:01:28 EST


On Wednesday 16 January 2013 10:47:12 Ben Hutchings wrote:
> On Wed, 2013-01-16 at 23:21 +0900, YOSHIFUJI Hideaki wrote:
> > Cong Wang wrote:
> > > (Cc'ing some glibc developers...)
> > >
> > > Hello,
> > >
> > > In glibc source file inet/netinet/in.h and kernel source file
> > > include/uapi/linux/in6.h, both define struct in6_addr, and both are
> > > visible to user applications. Thomas reported a conflict below.
> > >
> > > So, how can we handle this? /me is wondering why we didn't see this
> > > before.
>
> [...]
>
> > This is not a new issue. In addition to this,
> > netinet/in.h also conflits with linux/in.h.
> >
> > We might have
> >
> > #if !defined(__GLIBC__) || !defined(_NETINET_IN_H)
> >
> > #endif
> >
> > around those conflicting definitions in uapi/linux/in{,6}.h.
>
> This only solves half the problem, as <netinet/in.h> might be included
> after <linux/in.h>. Also, not all Linux userland uses glibc.

certainly true, but the current expectation is that you don't mix your ABIs.
if you're programming with the C library API, then use the C library headers.
if you're banging directly on the kernel, then use the kernel headers. not
saying it's a perfect solution, but it works for the vast majority of use
cases.
-mike

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