Fix show-xml filtering by interface name (issue #735,bsc#954758)

[rtorrero]

This PR adds filtering functionality to the show-xml command, with the following behaviour:

• wicked show-xml <ifname1> <ifname2>: show xml only for ifname1 and ifname2
• wicked show-xml all: show xml for all available network interfaces
• wicked show-xml: same as above, show all interfaces

This should address issue #735

[rtorrero]

I'm not entirely happy with the double for loop, it looks messy. I'm open to suggestions if that can be improved.
If there is no better way to do it using any of the ni_dbus_variant or ni_dbus_dict functions, variable naming could use some love too :p.

[mtomaschewski]

Please improve & fix as commented via pm mail :-)

[rtorrero]

Thanks for your comments. Hope those commits address all the issues. Awaiting your feedback :).

[mtomaschewski]

Could you please cleanup the (leading) space changes and adjust also the usage message? I'd also prefer to squash it into 1..3 clean & final commits instead of full evolution history adding 2nd loop & removing it again.

[mtomaschewski]

please remove the leading spaces. you may configure .gitconfig to show (and or fix) them, e.g. core.whitespace = fix,indent-with-non-tab,trailing-space

[rtorrero]

I've added your additional suggestions (usage info and trailing whitespaces), but I did it before squashing the commits. Should I have done those afterwards?

[mtomaschewski]

This looks very good now... There is still a bit odd usage inside of the show-xml, could you adjust it too please?

[rtorrero]

I'm not sure how to improve that one, I'm looking at how other subcommands have their usage section and doing the < --raw | [ <ifname ...>|all ] > thing would mean that we have to remove the 'Supported options' part (as --raw is one of the options). Could you provide more details?

[mtomaschewski]

Yes, your note should be sufficient to cover --raw case (until we refactor it to apply the filter to --raw too), but we should adjust at least:

- "wicked [options] show-xml <ifname|all>\n"
- "\nSupported options:\n"
+ "wicked show-xml [options] [ifname ... |all]\n"
+ "\n"
+ "Supported options:\n"

[rtorrero]

I got you, should be done :). Thanks for the feedback!

[mtomaschewski]

Could you please also remove the obsolete variable? :

main.c: In function ‘do_show_xml’:
main.c:613:14: warning: unused variable ‘ifname’ [-Wunused-variable]
  const char *ifname = NULL;
              ^

[mtomaschewski]

OK, fixed in a separate commit 54a8504c4