swclock: Use the same file for both saving and loading

[snh]

If no path is specified on the command-line when calling swclock, it defaults to saving and loading the last shutdown time from a file named shutdowntime:

openrc/src/swclock/swclock.c

Line 37 in 9380347

#define RC_SHUTDOWNTIME RC_SVCDIR "/shutdowntime"

I noticed swclock wasn't operating as I'd expect on Alpine Linux and went investigating to find that /etc/init.d/swclock was calling swclock with no path defined when saving the time:

openrc/init.d/swclock.in

Line 34 in 9380347

swclock --save

But providing the path of @SBINDIR@/openrc-run when loading the time:

openrc/init.d/swclock.in

Line 26 in 9380347

swclock --warn @SBINDIR@/openrc-run

Sure enough I found a file named /run/openrc/shutdowntime was being created, though on a tmpfs, and regardless, not being used when loading the time.

This PR updates /etc/init.d/swclock so the same file is used for both - @SBINDIR@/openrc-run. I chose this over using the default, as I've noted that systems such as Alpine Linux are placing shutdowntime in a location backed by tmpfs.

What I am changing hasn't changed in many many years, so either this has been broken for a long time, or I'm misunderstanding how it works, which is entirely possible, apologies if it is the later, I thought a PR rather than Issue would be more worthwhile in-case I am on the right track! 😄

Possibly closes #430.

[williamh]

You are close. The concern though is that @sbindir@ might be a read-only filesystem.
This works in start() because the call to swclock only reads the date/time, and the call that refers to swclock using @sbindir@/openrc-run is only used if the call on the line above it fails.
A better approach would be to make the location of the file used by swclock user configurable.
I'll open a pr for that.

[williamh]

This is fixed in #565.