[gentoo-soc] Week 1 Report for Musl support expansion to support GNOME desktop

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Hi folks,

The first week of coding period of this years Google Summer of Code has
come to an end, hence I'm sending my weekly report. For the first two
week I had planned to install the gnome-light meta package and patch any
issues that I come across. So I started with that, by installing
gnome-light meta package from gnome-base. This resulted in me coming
across four issues. The first two were rather easy to fix and I've
patched and submitted those patches. The other two have proven to be
rather difficult to debug hence with advice from my mentors I've decided
to come back to them later.

Coming to the issues itself, the first two were just missing defines
that are present in glibc but not in musl. The issues were in the
gnome-terminal and samba packages, the gnome-terminal was missing was
missing `W_EXITCODE` define while samba was missing `NETDB_INTERNAL` and
`NETDB_INTERNAL` defines. The other two issues are in ppp and lirsvg
package, however they can be avoided for now and I was able to get a
working gnome desktop on musl profile.

The issue with ppp was, ppp has been using `<net/ppp_defs.h>` however
this header file in not present in musl but glibc seems to provide it.
Hence I decided to use the `<linux/ppp_defs.h>` as this would be
available for both musl and glibc users and everyone could benefit from
from the patch. This however didn't seem to work and introduced a
different error. I've filed an issue upstream [1] and got a reply from
maintainer. The maintainer in their reply agrees that we should use be
using headers from Linux or whatever libc system uses, the maintainer
also has idea of including purely linux headers. There is already an
pull request for this particular issue and it's under review. To avoid
using ppp one can generally disable it using `-ppp` USE flag in
`make.conf`.

Comming to the librsvg issue, the problem with librsvg has proven rather
hard to debug, though I've tried my best to debug it. The issues seems
to be that, librsvg is crashing when trying to render a svg and this is
needed to get a gnome shell running. Hence when trying to run
gnome-shell or gdm we get a fail whale screen ( White screen with
message "Oh no! Something has gone wrong" with a sad face ). I, with
help from my mentors and leio, tried to debug it and found out the issue
happens the function `g_file_get_uri` tried to load a svg. Hence we
tried to find out which svg in particular was causing the issue by
selecting the frame in gdb and trying to print
`g_file_get_uri(data->gfile)`, which didn't help either, it just
resulted in a segmentation fault. After that I decided to file a bug
upstream [2], meanwhile we other various things like increasing the
stack size as there has been issues with musl's default stack size,
which happens to be small. I've got a reply on this issue from librsvg
developer, they have suggested to increase the stack size and try it,
but we've already tried it before but I'll give it another shot just to
any eliminate human errors. Coming week, we'll try further debugging
librsvg. For now, to get a running gnome desktop one can use a older
librsvg from ::gentoo (librsvg-2.40.21 from ::gentoo worked).

This should be comprehensive enough report for the first week, learned
new things about debugging, looking forward to learning and contributing
more. Thanks to my mentors ( sam and dilfridge ), leio ( Gentoo's GNOME
project lead ) for his time in helping me debug gnome-shell and Catcream
( fellow GSoC student ) for testing my the librsvg issue and confirming
it on his end.

[1]: https://github.com/ppp-project/ppp/issues/351
[2]: https://gitlab.gnome.org/GNOME/librsvg/-/issues/874
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Regards,
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