Support for Linux transparent proxy & asm/types.h

[Mark Kettenis]

   Date: Wed, 23 Dec 1998 20:13:43 +0100
   From: Andi Kleen <ak@muc.de>
   Cc: libc-alpha@cygnus.com
   Content-Type: text/plain; charset=us-ascii

   On Wed, Dec 23, 1998 at 05:20:41PM +0100, Mark Kettenis wrote:
   > On a related topic: I currently give this synopsis line for netlink
   > sockets:
   > 
   >    #include <linux/netlink.h>
   >    nl_socket = socket(PF_NETLINK, ....);
   > 
   >    To compile that snippet on glibc systems #include
   >    <asm/types.h> is needed.  Does glibc gurantee in future
   >    version that asm/types.h will continue to work?
   > 
   > No, we can't guarantee this since Linus doesn't want to commit
   > himself to keeping the Linux headers namespace clean.  So
   > programs that compile against glibc should not include any Linux
   > headers (i.e. no #include <asm/foo.h> or #include <linux/foo.h>).
   > If glibc doesn't provide a header (i.e. #include <sys/foo.h>),
   > the programmer is supposed to copy the needed defenitions from
   > the appropriate Linux header to a private header and use that.

   You want me to suggest that in the man page?  Sounds like a
   horrible kludge. I'll surely not do that.

Well your code snippet defenitely doesn't work on my system, since the
2.1.130 header doesn't include <ams/types.h> anymore.
The correct code would be:

   #include <sys/socket.h>
   nl_socket = socket (PF_NETLINK, ....);

But if the user actually wants to do something useful with the socket
he/she probably does need some of the constants in <linux/netlink.h>.
We had a <netlink/netlink.h> for a while in glibc, but IIRC it was
dropped because the kernel headers were changing too rapidly.  This
probably means that it is not worth documenting this (yet).

Mark