This mirrors the change done for systemd-resolved in
9793530228. Quoting that patch:
> We generally operate on the assumption that a source is "gone" as soon as we
> unref it. This is generally true because we have the only reference. But if
> something else holds the reference, our unref doesn't really stop the source
> and it could fire again.
In particular, we take temporary references from sd-event code, and when called
from an sd-event callback, we could temporarily see this elevated reference
count. This patch doesn't seem to change anything, but I think it's nicer to do
the same change as in other places and not rely on _unref() immediately
disabling the source.
This drops the "const" specifier from the opaque object parameters to
various functions in our API.
This effectively reverts #19292 and more.
Why drop this? Our public APIs should not leak too much information
about how stuff is implemented internally. In our public APIs we
shouldn't give too many guarantees we don#t want to necessarily keep.
Specifically: in many cases it makes sense that getters actually
generate/parse/allocate data on the fly, storing/caching the result
internally, to speed things up, do things lazily or to track memory
allocations so that they can be freed later. Doing this means we need to
change the objects, even though the getters are semantically a read
operation.
We want to retain the freedom that we can change things around
internally. By exposing the objects as "const" we remove a good chunk of
that, for little gain.
See sd_bus_creds_get_description() for a real example of a getter that
implicitly caches and thus modifies the relevant object.
This removes the "const" decorators from sd-dhcp and sd-netlink, two
APIs that we intend to make public eventually even though they still are
not, leaving us the chance to still fix this before it becomes set in
stone.
Why is this necessary? Several examples below.
- When a route sets prefsrc, then the address must be already assigned
(see issue #19285), and also it must be ready if IPv6.
- When a route or nexthop sets gateway, then the address must be reachable.
- When a route sets nexthop ID, then the corresponding nexthop must be
assigned.
- When a route sets multipath routes on another interface, then the
interface must exist and be ready to configure.
- When configuring address, the same address must not be under removing
(see issue #18108).
Etc,. etc,...
So, this makes all requests about addresses, routes, and nethops are once
stored in the queue, and will be processed when they are ready to configure.
Fixes#18108 and #19285.
We usually call specifier_printf() and then check the validity of
the result. In many cases, validity checkers, e.g. path_is_valid(),
refuse too long strings. This makes specifier_printf() refuse such
long results earlier.
Moreover, unit_full_string() and description field in sysuser now
refuse results longer than LONG_LINE_MAX. config_parse() already
refuses the line longer than LONG_LINE_MAX. Hence, it should be ok
to set the same value as the maximum length of the resolved string.
Let's make sure that our close handler unrefs a connection again that we
are already unreffing a few stack frames up by invalidating the pointer
first, and dropping the ref counter only after that.
Replaces: 39ad3f1c09Fixes: #18025
Zbigniew Jędrzejewski-Szmek
Lennart Poettering
Yu Watanabe