[Buildroot] [autobuild.buildroot.net] Daily results for 2020-09-05

[Yann E. MORIN]

All,

On 2020-09-06 07:07 -0000, Thomas Petazzoni spake thusly:
> Classification of failures by reason for master
>     mips     |          systemd-246           | NOK | http://autobuild.buildroot.net/results/229866ea234097b5d6c6104bf040f47fd22ffacc |     

So this is a reproducible build issue:

  - systemd #defines PROJECT_FILE (&__FILE__[STRLEN(RELATIVE_SOURCE_PATH) + 1])
    in an attempt to report only the basename of the files in messages;

  - so it has a static assert that __FILE__ is indeed longer that
    RELATIVE_SOURCE_PATH, otherwise the above would be an out-of-bound
    access;

  - RELATIVE_SOURCE_PATH is set by the systemd's meson.build, and
    contains the path of the sources relative to build directory; in
    Buildroot, if I understand systemd's code correctly, this will
    always be '.' .

  - but Buildroot, when BR2_REPRODUCIBLE=y, #defines __FILE__="" (i.e.
    an empty string, so that binaries do not embed local paths, and are
    thus bit-for-bit reproducible (except for other non-reproducibility
    causes).

As such, when Buildroot tries to do a reproducible build, the length of
__FILE__ will always be shorter than the length of RELATIVE_SOURCE_PATH + 1,
the former always being 0, while the latter being 2.

So we have a few avenues:

  - talk with upstream so they stop using __FILE__ altogether

  - talk to upstream so they optionally not use __FILE__

  - patch systemd ourselves and live for ever after with that patch

  - change our toolchain wrapper to use an arbitrarily long __FILE__

I've looked at Debian and Fedora, and they do not have a patch to get
rid of that.

Thoughts?

Regards,
Yann E. MORIN.

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