This macro will read a pointer of any type, return it, and set the
pointer to NULL. This is useful as an explicit concept of passing
ownership of a memory area between pointers.
This takes inspiration from Rust:
https://doc.rust-lang.org/std/option/enum.Option.html#method.take
and was suggested by Alan Jenkins (@sourcejedi).
It drops ~160 lines of code from our codebase, which makes me like it.
Also, I think it clarifies passing of ownership, and thus helps
readability a bit (at least for the initiated who know the new macro)
Apparently O_NONBLOCK is the modern name used in most documentation and
for most cases in our sources. Let's hence replace the old alias
O_NDELAY and stick to O_NONBLOCK everywhere.
Checking for validity of a PID is relatively easy, but let's add a
helper cal for this too, in order to make things more readable and more
similar to uid_is_valid(), gid_is_valid() and friends.
Let's add a proper validation function, since validation isn't entirely
trivial. Make use of it where applicable. Also make use of
AUDIT_SESSION_INVALID where we need a marker for an invalid audit
session.
This patch ensures that session devices are saved for each session.
In order to make the revokation logic work when logind is restarted, the
session devices are now saved in the session state files and their respective
file descriptors sent to PID1's fdstore in order to keep them open accross
restart.
This is mandatory in order to keep the revokation logic working. Indeed in case
of input-devices, the same file descriptors must be shared by logind and a
given session controller in order EVIOCREVOKE to work otherwise multiple
sessions can have device access in parallel.
This should be the only remaining and missing piece for making logind fully
restartable.
Fixes: #1163
When assigning a new session controller to a session, the VT is prepared so the
controller can expect the VT to be in a good default state.
However when logind is restarted and a session controller already took control
of a session, there's no need to prepare th VT otherwise logind may screw up
the VT state set by the controller.
This patch prevents the preparation of the VT in this case.
Embedding sd_id128_t's in constant strings was rather cumbersome. We had
SD_ID128_CONST_STR which returned a const char[], but it had two problems:
- it wasn't possible to statically concatanate this array with a normal string
- gcc wasn't really able to optimize this, and generated code to perform the
"conversion" at runtime.
Because of this, even our own code in coredumpctl wasn't using
SD_ID128_CONST_STR.
Add a new macro to generate a constant string: SD_ID128_MAKE_STR.
It is not as elegant as SD_ID128_CONST_STR, because it requires a repetition
of the numbers, but in practice it is more convenient to use, and allows gcc
to generate smarter code:
$ size .libs/systemd{,-logind,-journald}{.old,}
text data bss dec hex filename
1265204 149564 4808 1419576 15a938 .libs/systemd.old
1260268 149564 4808 1414640 1595f0 .libs/systemd
246805 13852 209 260866 3fb02 .libs/systemd-logind.old
240973 13852 209 255034 3e43a .libs/systemd-logind
146839 4984 34 151857 25131 .libs/systemd-journald.old
146391 4984 34 151409 24f71 .libs/systemd-journald
It is also much easier to check if a certain binary uses a certain MESSAGE_ID:
$ strings .libs/systemd.old|grep MESSAGE_ID
MESSAGE_ID=%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x
MESSAGE_ID=%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x
MESSAGE_ID=%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x
MESSAGE_ID=%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x
$ strings .libs/systemd|grep MESSAGE_ID
MESSAGE_ID=c7a787079b354eaaa9e77b371893cd27
MESSAGE_ID=b07a249cd024414a82dd00cd181378ff
MESSAGE_ID=641257651c1b4ec9a8624d7a40a9e1e7
MESSAGE_ID=de5b426a63be47a7b6ac3eaac82e2f6f
MESSAGE_ID=d34d037fff1847e6ae669a370e694725
MESSAGE_ID=7d4958e842da4a758f6c1cdc7b36dcc5
MESSAGE_ID=1dee0369c7fc4736b7099b38ecb46ee7
MESSAGE_ID=39f53479d3a045ac8e11786248231fbf
MESSAGE_ID=be02cf6855d2428ba40df7e9d022f03d
MESSAGE_ID=7b05ebc668384222baa8881179cfda54
MESSAGE_ID=9d1aaa27d60140bd96365438aad20286
The 'Sessions' property for both org.freedesktop.login1.User and
org.freedesktop.login1.Seat is marked as EmitsChangedSignal(false).
Trying to emit a change signal that includes the 'Sessions' property
leads to the signal not being sent at all.
Fixes#5210.
We don't have plural in the name of any other -util files and this
inconsistency trips me up every time I try to type this file name
from memory. "formats-util" is even hard to pronounce.
This way systemd is informed that we consider everything inside the scope as
"left-over", and systemd can log about killing it.
With this change systemd will log about all processes killed due to the session
clean-up on KillUserProcesses=yes.
Let's make sure we process session and inhibitor pipe fds (that signal
sessions/inhibtors going away) at a higher priority
than new bus calls that might create new sessions or inhibitors. This helps
ensuring that the number of open sessions stays minimal.
The deserialize_timestamp_value() is renamed timestamp_deserialize() to be more
consistent with dual_timestamp_deserialize()
And add the NULL check back on realtime and monotonic
GLIB has recently started to officially support the gcc cleanup
attribute in its public API, hence let's do the same for our APIs.
With this patch we'll define an xyz_unrefp() call for each public
xyz_unref() call, to make it easy to use inside a
__attribute__((cleanup())) expression. Then, all code is ported over to
make use of this.
The new calls are also documented in the man pages, with examples how to
use them (well, I only added docs where the _unref() call itself already
had docs, and the examples, only cover sd_bus_unrefp() and
sd_event_unrefp()).
This also renames sd_lldp_free() to sd_lldp_unref(), since that's how we
tend to call our destructors these days.
Note that this defines no public macro that wraps gcc's attribute and
makes it easier to use. While I think it's our duty in the library to
make our stuff easy to use, I figure it's not our duty to make gcc's own
features easy to use on its own. Most likely, client code which wants to
make use of this should define its own:
#define _cleanup_(function) __attribute__((cleanup(function)))
Or similar, to make the gcc feature easier to use.
Making this logic public has the benefit that we can remove three header
files whose only purpose was to define these functions internally.
See #2008.
This new setting configures the TasksMax= field for the slice objects we
create for each user.
This alters logind to create the slice unit as transient unit explicitly
instead of relying on implicit generation of slice units by simply
starting them. This also enables us to set a friendly description for
slice units that way.
The files are named too generically, so that they might conflict with
the upstream project headers. Hence, let's add a "-util" suffix, to
clarify that this are just our utility headers and not any official
upstream headers.
The previous coccinelle semantic patch that improved usage of
log_error_errno()'s return value, only looked for log_error_errno()
invocations with a single parameter after the error parameter. Update
the patch to handle arbitrary numbers of additional arguments.
When the controlling process exits, any existing file descriptors
for that FD will be marked as hung-up and ioctls on them will
file with EIO. To work around this, open a new file descriptor
for the VT we want to clean up.
Thanks to Ray Strode for help in sorting out the problem and
coming up with a fix!
https://github.com/systemd/systemd/issues/989
The open_terminal() function adds retries in case a terminal
is in the process of being closed when we open it, and should
generally be used to open a terminal. We especially need it
for code that a subsequent commit adds that reopens the terminal
at session shut-down time; such races would be more likely in
that case.
Found by Ray Strode.
Use mfree() where we can.
Drop unnecessary {}.
Drop unnecessary variable declarations.
Cast syscall invocations where explicitly don't care for the return
value to (void).
Reword a comment.
Let logind use the sd_bus_track helper object to track the controllers of
sessions. This does not only remove quite some code but also kills the
unconditional matches for all NameOwnerChanged signals.
The latter is something we should never ever do, as it wakes up the daemon
every time a client connects, which doesn't scale.
Make sure we release VT-positions when a session is closed. Otherwise,
lingering sessions will occupy VTs and prevent next logins from
succeeding.
Note that we already release session-devices when closing a session, so
there cannot be anyone using the VT anymore.
Some places invoked fflush() directly with their own manual error
checking, let's unify all that by using fflush_and_check().
This also unifies the general error paths of fflush()+rename() file
writers.
Spell out the proper name. Use 'pos' over 'position', and also update the
logind state file to do the same. Note that this breaks live updates.
However, we only save 'POSITION' on non-seat0, so this shouldn't bother
anyone for real. If you run multi-seat setups, you better restart a
machine on updates, anyway.
