Pre commit hook for PO files on git.gnome.org

After a little pestering by André I’ve made the following changes regarding PO file checking on git.gnome.org:

1. PO files are actually checked using msgfmt
2. Added a simple check to ensure keyword header in .desktop is properly translated

That PO files weren’t checked for syntax issues was pretty surprising for me, it seems no translator ever uploaded a PO file with a wrong syntax, else I assume the sysadmin team would’ve received a bugreport/ticket.

The check for a properly translated keyword header is implemented using sed:

sed -rn '/^#: [^\n]+\.desktop/{:start /\nmsgstr/!{N;b start};/\nmsgid [^\n]+;"/{/\nmsgstr [^\n]+;"/!p}}'

Or in English: match from /^#: .*\.desktop/ until /\nmsgstr/. Then if there is a msgid ending with ";, check if there also is a msgstr ending with ;". If msgstr doesn’t end with ;" but all other conditions apply: print the buffer (so #: line up to msgstr). The git hook itself just looks if the output is empty or not.

Example of the error message.

$ git push
Counting objects: 23, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 313 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
remote: ---
remote: The following translation (.po) file should ensure the translated content ends with a semicolon. (When updating branch 'master'.)
remote:
remote: po/sl.po
remote:
remote: The following part of the file fails to do this. Please correct the translation and try to push again.
remote:
remote: #: ../data/nautilus.desktop.in.in.h:3
remote: msgid "folder;manager;explore;disk;filesystem;"
remote: msgstr "mapa;upravljalnik;datoteke;raziskovalec;datotečni sistem;disk"
remote:
remote: After making fixes, modify your commit to include them, by doing:
remote:
remote: git add sl.po
remote: git commit --amend
remote:
remote: If you have any further problems or questions, please contact the GNOME Translation Project mailing list <gnome-i18n@gnome.org>. Thank you.
remote: ---
To ssh://git.gnome.org/git/nautilus
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'ssh://git.gnome.org/git/nautilus'

Note: explanation can probably be improved. The check is not just for Keywords, also for other things like e.g. mime types, etc.