[Rpm-maint] How to generate GNU make dependency file for a SPEC file automatically?

[Jeff Johnson]

> On Mar 26, 2018, at 6:15 PM, Francesco <francesco.montorsi at gmail.com> wrote:
> 
> Hi Jeff,
> thanks for your reply.
> 
> 
> 
> 2018-03-26 19:04 GMT+02:00 Jeff Johnson <n3npq at me.com>:
>> 
>> There isn't an explicit tool to convert rpmbuild dependencies to Makefile dependencies afaik.
>> 
>> OTOH, it's not impossibly hard to script a couple of missing pieces that are needed:
>> 
>> 1) Automate by rule generating a *.src.rpm from a (possibly modified) *.spec.
>> 
>> 2) Automate by rule installing a *.src.rpm into a local build directory. This requires configuring some rpm macros to map rpmbuild inputs/outputs into a single directory.
>> 
>> 3) Automate by rule rebuilding of binary *.rpm from a newer *.spec in the local build directory
>> 
>> You can find some useful rules using wild cards and % template rules in rpm5 sources: see the
>> tests/Makefile.am file for the pattern rules.
> 
> Honestly I'm not sure to understand what you mean... when you say "Automate by rule" you mean writing a GNU make rule, right?

Yes.

> Then it's clear to me step 1 and 2 but is not clear why should I get a newer .spec file in the local build directory only if some of my sources have changed: if step 1 and 2 are always executed by GNU make (which btw would be against my goal of running unneeded packaging operations) then I guess that the mtime of the .spec file in the local build directory will always change from run to run... what am I missing?
> 

Sorry to be obscure. The pattern rules I wrote had 2 *.spec files: the top level *.spec determined when a *.src.rpm should be made, which triggered an install not a subdirectories, with a 2nd *.spec (copy) that triggers a rpmbuild by rule.

Does that make sense? worksforme, for the purposes I needed, QA testing of a just built version of rpm within the buil tree ...

> Also I'm particularly interested in binary-only RPMs (I need such a tool for a commercial software)... to give you an idea, most of my RPM spec install sections look like:
> 
> %install
> make -C ../mysources mytarget_install DESTDIR=%{buildroot}
> 

That's pretty generic, yes. Meanwhile the real problem is that rpmbuild within Makefiles is kinda awkward.

>  
>> Alternatively, one could attempt generating a Makefile include rule.
>> 
>> Extract (and filter) rpmbuild dependencies from a spec (or *.src.rpm) file. RPM can query a spec file (or *.src.rpm), convert those (filtered) dependencies to package names, and convert the package names to file names that have a time stamp that can be included into a Makefile.
> 
> Sorry, I'm not sure I get this either... I know RPM allows you to query dependencies but you can only query the package names listed under "Requires:" isn't it?
> 

Basically yes. But to automate within a Makefile (like dependencies on *.h)' the build requirements need to be mapped onto a file name that has a time stamp.

> 
> Btw I have sketched out a possible "solution" for my problem: first time "make" is run, I call rpmbuild and build my binary RPM.
> Then (automatically via GNU make rules) I unzip that RPM into some temporary folder, I see what's inside and go search for MD5-sum matching files in the source build folder. Every time I find inside the source build folder a file that is inside the RPM, I write that into a .d file (same name of the RPM spec).
> The GNU makefile has an "include $(MY_SPEC_FILE_LIST:.spec=.d)" statement, so that it's aware of the auto-discovered dependencies of the spec file.
> Next time I run "make", it will be able to understand if the RPM is up to date or needs to be regenerated because some of the file it packages has been updated (perhaps as a result of the build process).
> 

Post a sample Makefile please. Lots of people have tried to use rpmbuild in Makefiles, and most of the solutions I have seen are rather awkward.

> Of course this process is not 100% accurate: in the %install section some temporary file may be generated and copied inside the RPM build root. Or files (e.g. config files) could be renamed when they get copied inside the build root. And maybe there are other cases as well.

My pattern rules have some *ahem* issues as well, but are good enough for "make test" automation.

(aside)
The issues happen while developing: the pattern rules implicitly fire a (perhaps buggy) rpm. Good enough, but sometimes  a pita.

> However that approach might cover a wide range of use cases... what do you think?
> 
> It would be nice to have some mechanism like that inside rpmbuild so that I can do
>       rpmbuild -MD myspec.spec --output=myspec.d
> and it generates such dependency file for GNU make...
> 

There aren't any clean or obvious solutions by rpmbuild design. Oh well ...

hth

73 de Jeff
> Thanks!
> 
> Francesco
> 
> 
> 
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