With https://github.com/systemd/mkosi/pull/630, we can set environment
variables for the build script in mkosi. Let's modify the build script
so we can set the version-tag option via an environment variable of the
same name. The default is the empty string which causes meson to fall
back to the default behavior (git version).
This variable (a.k.a. rootlibexecdir), was exposed through the .pc file, but
not as rpm macro.
The .pc file must be located in the package that provides libraries, which
pulls in a lot of dependencies. In Fedora, the macros are split out to a
separate package so that other packages which need to refer to some systemd
path but don't otherwise require it, can only pull in the (much smaller and
dependency-less) macros package. zram-generator uses the path to specify the
location of systemd-makefs, so by using the rpm macro we'll be able to use
a much smaller buildroot.
The cmp in ExecStartPost= was actually failing – ExecStartPost= has the
same StandardOutput as the rest of the service, so the output file is
truncated before cmp can compare it with the expected output – but the
test still passed because test_exec_standardoutput_truncate() calls
test(), which only checks the main result, rather than test_service(),
which checks the result of the whole service. Fix the test by merging
the ExecStartPost= into the ExecStart= – the cmp has to be part of the
same command line as the cat so that the file is not truncated between
the two processes.
Functions defined by us are supposed to return negative errno-style
errors on errors. laccess() is for access() what lstat() is for stat(),
but defined by us as a macro. This led to some confusion regarding error
handling.
Let's return a negative errno code just in case. This means callers can
it use either way: like access(), i.e. checking for a negative return
value + looking at errno, or like our own code, i.e. using the negative
errno code it returns.
vcs_tag() is slow. When the version-tag meson option is set,
we can use configure_file() directly to speed up incremental
builds.
Before (with version-tag set to v247):
```
‣ Running build script...
[1/418] Generating version.h with a custom command
real 0m0.521s
user 0m0.229s
sys 0m0.067s
```
After (with version-tag set to v247):
```
‣ Running build script...
ninja: no work to do.
real 0m0.094s
user 0m0.048s
sys 0m0.022s
```
Susant Sahani
Yu Watanabe
Lennart Poettering
Adam Nielsen
Susant Sahani
Zbigniew Jędrzejewski-Szmek
Luca Boccassi
Daan De Meyer
Frantisek Sumsal
Lucas Werkmeister