Let's make sure that sd_varlink_error() always returns an error code, so
that we can use it in a style "return sd_varlink_error(…);" everywhere,
which has two effects: return a good error reply to clients, and exit
the current stack frame with a failure code.
Interestingly sd_varlink_error_invalid_parameter() already worked like
this in some cases, but sd_varlink_error() itself didn't.
This is an alternative to the error handling tweak proposed in #34882,
but I think is a lot more generically useful, since it establishes a
pattern.
I checked our codebase, and this change should generally be OK without
breaking callsites, since the current callers (with exception of the
machined case from #34882) called sd_varlink_error() in the outermost
varlink method call dispatch stack frame, where this behaviour change
does not alter anything.
This is similar btw, how sd_bus_error_setf() and friends always return
error codes too, synthesized from its parameters.
If an ifindex is specified, we are modifying the existing interface.
Hence, these flags should not be set. Otherwise, the request will be
refused with -EEXIST.
We often used a pattern like if (!FLAGS_SET(flags, SD_JSON_FORMAT_OFF)),
which is rather verbose and also contains a double negative, which we try
to avoid. Add a little helper to avoid an explicit bit check.
This change clarifies an aditional thing: in some cases we treated
SD_JSON_FORMAT_OFF as a flag (flags & SD_JSON_FORMAT_OFF), while in other cases
we treated it as an independent enum value (flags == SD_JSON_FORMAT_OFF).
In the first form, flags like SD_JSON_FORMAT_SSE do _not_ turn the json
output on, while in the second form they do. Let's use the first form
everywhere.
No functional change intended.
Initially I wasn't sure if this helper should be made public or just internal,
but it seems such a common pattern that if we expose the flags, we might just
as well expose it too, to make life easier for any consumers.
The calls are now unused, and we generally prefer if people send a PID
triplet rather than a single PID, hence stop supporting a high-level
dispacher for pid_t.
The PID_AUTOMATIC value is now properly recognized by the PidRef logic
too. This needed some massaging of header includes, to ensure pidref.h
can access process-util.h's definitions and vice versa.
So far, at the one place we sent a PID over Varlink we did so as a
simple numeric pid_t value. That's of course is racy, since classic PIDs
are recycled too eagerly.
Let's address that, by passing around JSON objects distantly resembling our
PidRef structure. Note that this JSON object does *not* contain the
pidfd, however, but just the pidfd inode number if known.
I originally planned to include the pidfd in some direct form, but I
figured that's not really the best idea, since we always need a
side-channel of some form for that (i.e. AF_UNIX/SCM_RIGHTS), but we
should be able to report about PIDs even without that.
Moreover, while sending the pid number and pidfd id around should always
be OK to do, it's a lot more problematic to always send a pidfd around,
since that implies that fd passing is on and it is OK to install fds
remotely in some IPC peers fd table. For example, when doing a wild dump
of service manager service state we really shouldn't end up with a bunch
of fds installed in our client's fd table.
Hence, all in all I think it is cleaner to define a structure carrying
pid number and pidfd inode id, wich is passed directly as JSON. And then
optionally, in a separate field also pass around a pidfd where it makes
sense.
Note that sending around pidfds is not that beneficial anymore if we
have the pidfd inode id, because we can always securely and reliably get
a pidfd back from a pair of pid + inode id: first we do pidfd_open() on
the pid, and then we check if it is really the right one by comparing
.st_ino after fstat().
This logic is implemented gracefully: if for some reason pidfd/pidfd
inode nrs are not available (too old kernel), we'll fall back to plain
PID numbers.
The dispatching logic knows two distinct levels of validation of the
provided PID data: if SD_JSON_STRICT is specified we'll acquire a pidfd
for the PID, thus verifying it currently exists and failing if it
doesn't. If the flag is not set, well just store the provided info
as-is, will try to acquire a pidfd for it, but not fail if we cannot.
Both modes are important in different contexts.
Also note that in addition to the pidfd inode nr we always store the
current boot ID of the system in the JSON object, since only the
combination of pidfd inode nr and boot ID of the system really is a
world-wide unique reference to a process.
When dispatching a JSON pid field we operate somewhat gracefully: we
either support the triplet structure of pid, pid inode nr, boot id, or
we accept a simple classic UNIX pid.
- use uint8_t, uint16_t, and so on, rather than unsigned char, unsigned
short, and so on, respectively,
- rename output parameters to ret or ret_xyz,
- add several missing assertions.
This is the only place where xdg_user_dir() is needed and
makes sense. All other invocations have been replaced with
user_search_dirs() - see previous commits for details.
* Rename user_dirs() -> user_unit_search_dirs() and port to
user_search_dirs()
* Use STRV_IFNOTNULL to guard paths that could be NULL,
assert otherwise
xdg_user_dirs() doesn't seem well-organized currently.
In all other xdg_user_*() funcs we assume /etc/xdg/systemd
to be a symlink to /etc/systemd/, hence it is the odd one out.
Also, when the relevant envvar is unset, it only returns
the global search dirs.
sd_path_lookup() actually covers this nicely with SD_PATH_SEARCH_*,
where the combined search paths (from user home and system) are used.
Therefore, let's introduce a wrapper for that, and deprecate xdg_user_dirs()
(would be removed in later commits).
Note that -ENXIO reported by xdg_user_config_dir() is now properly
propagated rather than ignored, as unlike XDG_RUNTIME_DIR, XDG_CONFIG_HOME
has a default value hence ENXIO is not really expected.
Lennart Poettering
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Integral
Ivan Kruglov
Luca Boccassi
Mike Yuan