check for rpmlib version

[oliverkurth]

Is there a way to check at compile time for the rpmlib version?

In this particular case I want to use the enum value RPMTRANS_FLAG_NODB of enum rpmtransFlags_e in include/rpm/rpmts.h, but stay compatible with older versions that do not have this implemented. Since it's an enum, I cannot use #ifdef. So alternatively I thought I can use a macro that lets me check the version of rpmlib.

[pmatilai]

You can test for symbol existence without it being a macro too, details depend on the buildsystem of your project.
The rpm (not library) version is exposed via RPMVERSION (and rpmEVR) variable when you include rpm/rpmlib.h, but version based checks are best avoided.

[oliverkurth]

Thanks for replying.

I have this code:

...
                    } else if (strcmp(token, "nodb") == 0){
                        pConf->rpmTransFlags |= RPMTRANS_FLAG_NODB;
                    } else if (strcmp(token, "noconfigs") == 0){
                        pConf->rpmTransFlags |= RPMTRANS_FLAG_NOCONFIGS;
                    } else {
                        pr_err("unknown tsflag '%s'\n", token);
...

so for RPMTRANS_FLAG_NODB I want to build this conditionally, depending on whether RPMTRANS_FLAG_NODB is defined or not. As I said, I cannot use #ifdef RPMTRANS_FLAG_NODB because it's an enum value, not a macro. What do you recommend to do here?

FWIW, the project uses cmake. It's https://github.com/vmware/tdnf . Of course I could create some setting like HAVE_RPMTRANS_FLAG_NODB and set that as an argument to cmake, but I'd prefer something automatic.

[pmatilai]

FWIW, this isn't an rpm issue at all. It's like any old feature test, you test for the symbol in cmake, and define something you can test with ifdef. There are multiple ways to do that.

[oliverkurth]

I got that. It would be good if rpmlib had a macro that can just be tested, to save some work, and not having to write a hack to test for it. If you (or anyone) knows of any similar code that does that, it would be great if you can share.