This adds an API for retrieving an app-specific machine ID to sd-id128.
Internally it calculates HMAC-SHA256 with an 128bit app-specific ID as payload
and the machine ID as key.
(An alternative would have been to use siphash for this, which is also
cryptographically strong. However, as it only generates 64bit hashes it's not
an obvious choice for generating 128bit IDs.)
Fixes: #4667
This adds a new invocation ID concept to the service manager. The invocation ID
identifies each runtime cycle of a unit uniquely. A new randomized 128bit ID is
generated each time a unit moves from and inactive to an activating or active
state.
The primary usecase for this concept is to connect the runtime data PID 1
maintains about a service with the offline data the journal stores about it.
Previously we'd use the unit name plus start/stop times, which however is
highly racy since the journal will generally process log data after the service
already ended.
The "invocation ID" kinda matches the "boot ID" concept of the Linux kernel,
except that it applies to an individual unit instead of the whole system.
The invocation ID is passed to the activated processes as environment variable.
It is additionally stored as extended attribute on the cgroup of the unit. The
latter is used by journald to automatically retrieve it for each log logged
message and attach it to the log entry. The environment variable is very easily
accessible, even for unprivileged services. OTOH the extended attribute is only
accessible to privileged processes (this is because cgroupfs only supports the
"trusted." xattr namespace, not "user."). The environment variable may be
altered by services, the extended attribute may not be, hence is the better
choice for the journal.
Note that reading the invocation ID off the extended attribute from journald is
racy, similar to the way reading the unit name for a logging process is.
This patch adds APIs to read the invocation ID to sd-id128:
sd_id128_get_invocation() may be used in a similar fashion to
sd_id128_get_boot().
PID1's own logging is updated to always include the invocation ID when it logs
information about a unit.
A new bus call GetUnitByInvocationID() is added that allows retrieving a bus
path to a unit by its invocation ID. The bus path is built using the invocation
ID, thus providing a path for referring to a unit that is valid only for the
current runtime cycleof it.
Outlook for the future: should the kernel eventually allow passing of cgroup
information along AF_UNIX/SOCK_DGRAM messages via a unique cgroup id, then we
can alter the invocation ID to be generated as hash from that rather than
entirely randomly. This way we can derive the invocation race-freely from the
messages.
Old libdbus has a feature that the process is terminated whenever the the bus
connection receives a disconnect. This is pretty useful on desktop apps (where
a disconnect indicates session termination), as well as on command line apps
(where we really shouldn't stay hanging in most cases if dbus daemon goes
down).
Add a similar feature to sd-bus, but make it opt-in rather than opt-out, like
it is on libdbus. Also, if the bus is attached to an event loop just exit the
event loop rather than the the whole process.
This adds an optional "recursive" counting mode to sd_bus_track. If enabled
adding the same name multiple times to an sd_bus_track object is counted
individually, so that it also has to be removed the same number of times before
it is gone again from the tracking object.
This functionality is useful for implementing local ref counted objects that
peers make take references on.
This extends the existing event loop iteration counter to 64bit, and exposes it
via a new function sd_event_get_iteration(). This is helpful for cases like
issue #3612. After all, since we maintain the counter anyway, we might as well
expose it.
(This also fixes an unrelated issue in the man page for sd_event_wait() where
micro and milliseconds got mixed up)
Also, expose this via the "journalctl --file=-" syntax for STDIN. This feature
remains undocumented though, as it is probably not too useful in real-life as
this still requires fds that support mmaping and seeking, i.e. does not work
for pipes, for which reading from STDIN is most commonly used.
This adds two new calls to get the list of all journal fields names currently in use.
This is the low-level support to implement the feature requested in #2176 in a more optimized way.
This introduces two new helpers alongside sd_bus_path_{encode,decode}(),
which work similarly to their counterparts, but accept a format-string as
input. This allows encoding and decoding multiple labels of a format
string at the same time.
If code enqueues a message on one of the default busses, but doesn't
sync on it, and immediately drops the reference to the bus again, it
will stay queued and consume memory. Intrdouce a new call
sd_bus_default_flush_close() that can be invoked at the end of programs
(or threads) and flushes out all unsent messages on any of the default
busses.
This adds a new sd_pid_get_cgroup() call to sd-login which may be used
to query the control path of a process. This is useful for programs when
making use of delegation units, in order to figure out which subtree has
been delegated.
In light of the unified control group hierarchy this is finally safe to
do, hence let's add a proper API for it, to make it easier to use this.
sd_bus_flush_close_unref() is a call that simply combines sd_bus_flush()
(which writes all unwritten messages out) + sd_bus_close() (which
terminates the connection, releasing all unread messages) +
sd_bus_unref() (which frees the connection).
The combination of this call is used pretty frequently in systemd tools
right before exiting, and should also be relevant for most external
clients, and is hence useful to cover in a call of its own.
Previously the combination of the three calls was already done in the
_cleanup_bus_close_unref_ macro, but this was only available internally.
Also see #327
Add new calls sd_bus_open() and sd_bus_default() for connecting to the
starter bus a service was invoked for, or -- if the process is not a
bus-activated service -- the appropriate bus for the scope the process
has been started in.
A compatibility libsystemd-login library is created which uses
.symver and ifunc magic proposed by Lennart to make programs linked
to the old library name continue to work seamlessly.
Unfortunately the bfd linker crashes:
https://sourceware.org/bugzilla/show_bug.cgi?id=16467
This will be fixed in binutils 2.25.
As a work-around, gold can be used:
LDFLAGS=-Wl,-fuse-ld=gold
Unfortunately the switch to pick the linker appeared in gcc 4.8.
This also doesn't work with LLVM:
http://llvm.org/bugs/show_bug.cgi?id=11897
This brings the calls into similar style as the respective functions in
libsystemd-journal, and also is a bi shorter and more descriptive since
it clarifies the time unit used.
aeywalee