[pacman-dev] makepkg enhancements: globstar and variable expansions in PURGE_TARGETS, MAN_DIRS, etc.

[Ciprian Dorin, Craciun]

On Sat, Nov 14, 2009 at 8:44 AM, Allan McRae <allan at archlinux.org> wrote:
> Ciprian Dorin, Craciun wrote:
>>
>>    Hy everybody!
>>
>>    While building some custom packages for a stripped down Linux
>> server, I've hit the following problems:
>>    * the cause of the problems is from the pact that my packages are
>> each in it's own folder like: /packages/bash--4.0--1,
>> /packages/busybox--1.15.2--1, etc., and thus,
>>    * MAN_DIRS, DOC_DIRS, STRIP_DIRS and PRUNE_TARGETS doesn't work,
>> as I have no way to use ${pkgname}, etc in there;
>>    * in PRUNE_TARGETS there is no way to specify file patterns (like
>> '*.a', or '*.la'), but only from certain folders; (for example I can
>> say '*.a', but not '../lib/*.a'; also I can not specify unknown number
>> of parents, like '.../lib/**/*.a';
>>
>>    As a consequence, I propose (and if accepted I also have the
>> patches for) the following enhancements:
>>    * allow the patterns in MAN_DIRS, etc. to be evaluated at the
>> proper time execution time (when we access MAN_DIRS), not at
>> configuration time (when we define MAN_DIRS); this can be achieved by
>> (single) quoting the patterns like:
>> 'package/${pkgname}--${pkgver}--${pkgrel}/{,share/}man' and then
>> expansion by using eval;
>
> You can use
>
> MAN_DIRS=({package/*/,}{usr{,/local}{,/share},opt/*}/{man,info})
>
> and that will work.  An eval statement is evil.

    I don't know this for sure, but I assume that the makepkg.conf
file is sourced before actually going to build or package. Thus in
order for `package/*/` to work it must already exist in the current
folder.

    For example I've searched makepkg.sh for where the config file is
read, and I've found that it's hold in the MAKEPKG_CONF variable. And
the only place it's sourced is just before executing anything. This
means that (maybe) my previous assumption is right, and that
`package/*` or `opt/*` doesn't work.

    I agree that `eval` is evil. (If you ask me Bash is the most evil
programming language from them all, but I still do about 25% of my
programming in Bash...) So coming back to eval, in order to make my
use-case happen we have two options:
    * either we source MAKEPKG_CONF before each operation,
    * or we use eval on our patterns, and we single quote the patterns
in the config file;


>>    * allow enhanced pattern types for PURGE_TARGETS, like:
>>        * the same lazy evaluation as above;
>>        * if a pattern starts with '=' then it must exactly match a file
>> name;
>>        * if a pattern starts with '+' then it is a glob pattern (or
>> globstar), like:
>> 'packages/${pkgname}--${pkgver}--${pkgrel}/lib/**/*.a'
>
> These seem to be able to be handled in much the same way as MAN_DIRS above.

    No it is not. For example if I have
usr/lib/something/libsomething.a, I cannot purge libsomething.a unless
I explicitly say `*.a` (which could erase even other files in other
folders), or `usr/lib/*/*.a`, which forces me to know that I have
folders. (Thus eliminating the generality of makepkg.conf.)

    But again, it doesn't work, as explained above, because
usr/lib/*/*.a should already exist at source time in order to work.


>>        * if a pattern ends with '/' then we use `rm -Rf`, else we use `rm
>> -f`
>
> Instead of ending in /, end it in /* and combine with !emptydirs?

    Again it doesn't work. If a folder contain subfolders it shall
eliminate only the files in the parent, but not files in children.

    Also emptyfolders is a packaging option, and purging should be
able to remove a folder completely without leanig on the emptyfolders
support. (For example there could be cases where a package should
contain an empty folder.)


>>        * maybe if a pattern starts with '@' then it is a regular
>> expression, etc. (this I have not implemented);
>>
>>    Any comments?
>
> This all sounds overcomplicated.  Before considering this further, I would
> like to see an example that can not be handled by the current setup.
>
> Allan

    I hope that my examples are enough to show that there is a
imitation in current *_DIRS and PURGE_TARGETS.

    If I'm wrong about the conf file sourcing please correct me, but
from what I've seen I think I'm right.

    Thanks,
    Ciprian.