Document how to easily use `%{uncompress}` to expand source archives

[voxik]

The %{uncompress} macro is nowadays build on top of rpmuncompress, therefore it can be used to expand sources in this way:

%{uncompress: -x %{SOURCE1}}

which is quite neat IMHO. However, it is not easy to defer from the documentation that this works. So the easy thing should be to document this.

The other option might be (if I get correctly how the RPM macros work) to add e.g. the -x as an macro option. Then it should be possible to use even something like:

%uncompress -x %{SOURCE1}

and naturally, this would also meant the -x would get documented as an option of the macro

BTW since I am here, the macro in its documented form does not look very useful. It is not used in Fedora as I can tell. Previously, there at lease used to be this example, but it seems this example is now gone. I wish it was re-instantiated in some form

[pmatilai]

That this works now is basically an unintended side-effect of the fact that %uncompress just passes any arguments to rpmuncompress, and that's not something we want to advertise, macros should validate their own options. But none of the built-ins take options so there's a bunch of infra missing for that.

OTOH, if all you want is to call rpmuncompress, than just call it by that name (%__rpmuncompress) and there is no issue at all.

[voxik]

That this works now is basically an unintended side-effect

I thought that might be the case

than just call it by that name (%__rpmuncompress)

Frankly, using double underscore macro does not feel any better than then -x option.

Just FTR, I am exploring if this is a possibility, because if I remember correctly, rpmlint complains about unused sources when they are expanded by plain tar. Using some standard macro could help to mitigate this (and also I have hard times remembering the tar expand options 🙈).

And yes, I am aware of -b / -a options of %setup. But using -a I risk inadvertently including something into resulting RPM and using -b means that I have to ln / cp / mv test sources into the buildroot in %check section. I wish there was some standardized option to expand test archives in there.

[pmatilai]

Frankly, I don't expect anybody to use, much less remember, the esoteric multi-source extract options of %setup 😄 I don't remember them either.

%uncompress as a macro is more of a historical artifact now, but I agree the double-underscore %__rpmuncompress isn't inviting to use. Perhaps the right thing to do is move rpmuncompress out of /usr/lib/rpm into /usr/bin to one doesn't "need" silly macros to call it. I was on a crusade to solve something else when splitting it into a separate command, and while the case of packagers using it directly was on the back of my mind, I didn't really think it through it seems.

So ... lets do just that. There's nothing about rpmuncompress that demands it be only called from inside rpm(build).