We already allowed variables to be declared in the middle of a function
(whenever a new scope was opened), so this isn't such a big change. Sometimes
we would open a scope just to work around this prohibition.
But sometimes the code can be much clearer if the variable is declared
somewhere in the middle of a scope, in particular if the declaration is
combined with initialization or acquisition of some resources. So let's allow
this, but keep things in the old style, unless there's a good reason to move
the variable declaration to a different place.
This is mostly fall-out from d1a1f0aaf0,
however some cases are older bugs.
There might be more issues lurking, this was a simple grep for "%m"
across the tree, with all lines removed that mention "errno" at all.
Previously the enumerate() callback defined for each unit type would do
two things:
1. It would create perpetual units (i.e. -.slice, system.slice, -.mount and
init.scope)
2. It would enumerate units from /proc/self/mountinfo, /proc/swaps and
the udev database
With this change these two parts are split into two seperate methods:
enumerate() now only does #2, while enumerate_perpetual() is responsible
for #1. Why make this change? Well, perpetual units should have a
slightly different effect that those found through enumeration: as
perpetual units should be up unconditionally, perpetually and thus never
change state, they should also not pull in deps by their state changing,
not even when the state is first set to active. Thus, their state is
generally initialized through the per-device coldplug() method in
similar fashion to the deserialized state from a previous run would be
put into place. OTOH units found through regular enumeration should
result in state changes (and thus pull in deps due to state changes),
hence their state should be put in effect in the catchup() method
instead. Hence, given this difference, let's also separate the
functions, so that the rule is:
1. What is created in enumerate_perpetual() should be started in
coldplug()
2. What is created in enumerate() should be started in catchup().
This reworks how device units are "powered on".
This makes sure that any device changes that might have happened while
we were restarting/reloading will be noticed properly. For that we'll
now properly serialize/deserialize both the device unit state and the
device "found" flags, and restore these initially in the "coldplug"
phase of the manager deserialization. While enumerating the udev devices
during startup we'll put together a new "found" flags mask, which we'll
the switch to in the "catchup" phase of the manager deserialization,
which follows the "coldplug" phase.
Note that during the "coldplug" phase no unit state change events are
generated, which is different for the "catchall" phase which will do
that. Thus we correctly make sure that the deserialized state won't pull
in new deps, but any device's change while we were reloading would.
Fixes: #8832
Replaces: #8675
This is very similar to the existing unit method coldplug() but is
called a bit later. The idea is that that coldplug() restores the unit
state from before any prior reload/restart, i.e. puts the deserialized
state in effect. The catchup() call is then called a bit later, to
catch up with the system state for which we missed notifications while
we were reloading. This is only really useful for mount, swap and device
mount points were we should be careful to generate all missing unit
state change events (i.e. call unit_notify() appropriately) for
everything that happened while we were reloading.
