If we created the dir successfully, we let chmod_and_chown_at() do its thing
and shouldn't go into the part where we check if the existing directory has the
right permissions and ownership and possibly adjust them. The code was doing
that, by relying on the fact that chmod_and_chown_at() does not return -EEXIST.
That's probably true, but seems unnecessarilly complicated.
Follow-up for c1b1492a94.
When a service deactivates and is then automatically restarted via
Restart= we currently quickly transition through
SERVICE_DEAD/SERVICE_FAILED. Which is weird given it's not the
normal ("permanent") dead/failed state, but a transitory one we
immediately leave from again. We do this so that software that looks for
failures/successes can take notice, even if we restart as a consequence
of the deactivation.
Let's clean this up a bit: let's introduce two new states:
SERVICE_DEAD_BEFORE_AUTO_RESTART and SERVICE_FAILED_BEFORE_AUTO_RESTART
that are used for the transitory states. Both the SERVICE_DEAD and
SERVICE_DEAD_BEFORE_AUTO_RESTART will map to the high-level
UNIT_INACTIVE state though. (and similar for the respective failed
states). This means the high-level state machine won't change by this,
only the low-level one.
This clearly seperates the substates, which makes the state engine
cleaner, and allows clients to follow precisely whether we are in a
transitory dead/failed state, or a permanent one, by looking at the
service substate. Moreover it allows us to remove the 'n_keep_fd_store'
which so far we used to ensure the fdstore was not released during this
transitory dead/failed state but only during the permanent one. Since we
can now distinguish these states properly we can just use that.
This has been bugging me for a while. Let's clean this up.
Note that the unit restart logic is already nicely covered in the
testsiute, hence this adds no new tests for that.
And yes, this could be considered a compat break, but sofar we took the
liberty to make changes to the low-level state machine (i.e. SERVICE_xyz
states, sometimes called "substates") without considering this a bad
breakage – the high-level state machine (i.e. UNIT_xyz states) should
be considered API that cannot be changed.
LOG_SET_PREFIX() sets a logging prefix for the current block. The
prefix is prepended to every logging message in the block, followed
by ": ". If a logging prefix is already configured, it is overridden
for the duration of the block, after which it is restored.
A use case for this macro is when we're operating on an image or
directory (using --root or --image). We can use LOG_SET_PREFIX() to
prefix all logging messages with the directory or image that we're
operating on.
The reason why get_process_cmdline() is so complicated is that we
need to escape and quote arguments for building a single result
string.
That's necessary when we want to log or print the command line.
However, when we want to parse the command line, it is not necessary
that the result is a single string, but can be strv.
This will be used when we parse the command line.
The /proc/self/fd/ interface cannot be used to follow symlinks pinned
via O_PATH. Add a comment + test for that. Moreover, using fd_reopen()
with O_NOFOLLOW cannot work. Add an explicit check and test for that, to
make behaviour uniform.
Chasing symlinks is a core function that's used in a lot of places
so it deservers a less verbose names so let's rename it to chase()
and chaseat().
We also slightly change the pattern used for the chaseat() helpers
so we get chase_and_openat() and similar.
