'/etc/.updated' is created without using a temporary file, this can be
problematic with filesystems that cache writes. Modify so that the
timestamp is written to a temporary file and then use an atomic move
to move it to its correct place.
This is a follow-up for fb8b0869a7, and makes a
couple of minor clean-up changes:
- The field name in the timestamp file is changed from "TimestampNSec=" to
"TIMESTAMP_NSEC=". This is done simply to reflect the fact that we parse the
file with the env var file parser, and hence the contents should better
follow the usual capitalization of env vars, i.e. be all uppercase.
- Needless negation of the errno parameter log_error_errno() and friends has
been removed.
- Instead of manually calculating the nsec remainder of the timestamp, use
timespec_store().
- We now check whether we were able to write the timestamp file in full with
fflush_and_check() the way we usually do it.
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
As a followup to 086891e5c1 "log: add an "error" parameter to all
low-level logging calls and intrdouce log_error_errno() as log calls
that take error numbers", use sed to convert the simple cases to use
the new macros:
find . -name '*.[ch]' | xargs sed -r -i -e \
's/log_(debug|info|notice|warning|error|emergency)\("(.*)%s"(.*), strerror\(-([a-zA-Z_]+)\)\);/log_\1_errno(-\4, "\2%m"\3);/'
Multi-line log_*() invocations are not covered.
And we also should add log_unit_*_errno().
In order to support offline updates to /usr, we need to be able to run
certain tasks on next boot-up to bring /etc and /var in line with the
updated /usr. Hence, let's devise a mechanism how we can detect whether
/etc or /var are not up-to-date with /usr anymore: we keep "touch
files" in /etc/.updated and /var/.updated that are mtime-compared with
/usr. This means:
Whenever the vendor OS tree in /usr is updated, and any services that
shall be executed at next boot shall be triggered, it is sufficient to
update the mtime of /usr itself. At next boot, if /etc/.updated and/or
/var/.updated is older than than /usr (or missing), we know we have to
run the update tools once. After that is completed we need to update the
mtime of these files to the one of /usr, to keep track that we made the
necessary updates, and won't repeat them on next reboot.
A subsequent commit adds a new ConditionNeedsUpdate= condition that
allows checking on boot whether /etc or /var are outdated and need
updating.
This is an early step to allow booting up with an empty /etc, with
automatic rebuilding of the necessary cache files or user databases
therein, as well as supporting later updates of /usr that then propagate
to /etc and /var again.
