Re: [lwip-devel] Desiderata for 2.2.0: better support for Debian packaging and VirtualSquare

[Joan Lledó]

Hi,

El 8/1/23 a les 19:10, Renzo Davoli ha escrit:
> You are right. This approach was to minimize the impact for the other
> architectures that may include src/Filelists.cmake.
> Any other way to exclude slipif fits, e.g. a cmake variable used as a flag,
> say if LWIP_EXCLUDE_SLIPIF is set slipif.c is *not* added.

I don't have a strong opinion, if the alternatives are too complex it's 
OK for me to apply the patch as it is.

> I have just:
> * got the debian package source: 'apt-get source liblwip0'
> * added slipif.c in /src/FileLists.cmake
>    set(lwipnetif_SRCS
>        ${LWIP_DIR}/src/netif/ethernet.c
>        ${LWIP_DIR}/src/netif/bridgeif.c
>        ${LWIP_DIR}/src/netif/bridgeif_fdb.c
>        ${LWIP_DIR}/src/netif/slipif.c
>    )
>
> * built and installed the debian package:
>    $ debuild -b -us -uc
>    $ cd ..
>    $ sudo dpkg -i liblwip0_2.1.3+dfsg1-2_amd64.deb
>    $ sudo dpkg -i liblwip-dev_2.1.3+dfsg1-2_amd64.deb
>
> * compiled a test source... here is what I got:
>    $ gcc -o cli cli.c -I /usr/include/lwip -llwip
>    /usr/bin/ld: 
> /usr/lib/gcc/x86_64-linux-gnu/12/../../../x86_64-linux-gnu/liblwip.so: 
> undefined reference to `sio_tryread'
>    /usr/bin/ld: 
> /usr/lib/gcc/x86_64-linux-gnu/12/../../../x86_64-linux-gnu/liblwip.so: 
> undefined reference to `sio_read'
>    collect2: error: ld returned 1 exit status
>
> IMO slipif.c must be skipped, or an implementation of sio_tryread and
> sio_read must be provided, maybe a stub implementation, otherwise
> there are unresolved symbols.

OK, I'm probably wrong here, could you send me the code for cli.c, please?

> Again my approach was to be as conservative as possible to avoid
> side effects for other architectures/projects.
>
> Your "port" patch for Debian adds a specific lwipopts.h file and two
> 'external headers': posix/inet.h, posix/sockets.h
> Your lwipopts.h is significantly different from that in contrib/port/unix/lib
> and the include files are not in the lwip source tree, thus the idea to add
> a specific linux lib directory under the unix port.
>
> Maybe you have a better view and knowledge of the projects using
> the unix/lib code and you can see that it is safe to merge/update the code of
> the unix library.
>
> I vote for a new library, it is a surely safe choice. If the name linuxlib is
> misleading we can call it debianlib or posixlib (one main point
> is that the new lib uses posix compatible socket definitions).
> The code needed for the new lib is just:
> CMakeLists + lwipopts.h + posix/inet.h + posix/sockets.h

posixlib sounds good to me. I forgot to mention: I don't mind changing 
the license to BSD to make the patches upstream.

>  From a very quick check it seems that the 'max_sockets' patch applies
> almost flawlessly.
> Apart from some line offsets, the only changes needed appear to be:
> * a problem with the context at src/api/sockets.c:1777, the current
> patch fails due to a different name of a variable in the previous line,
> it needs to be patched by hand:
> -  done_socket(&sockets[i - LWIP_SOCKET_OFFSET]);
> +  done_socket(translate_socket(i - LWIP_SOCKET_OFFSET));
> * the new path of the lwipopts.h file.

Applying it to which version? to 2.1.3? Yes, max_sockets for 2.1.2 
applies fine to 2.1.3, which made upgrading the package easier, but it 
might not be the case for next versions.

Regards,
Joan