Sometimes it makes sense to hard kill a client if we die. Let's hence
add a third FORK_DEATHSIG flag for this purpose: FORK_DEATHSIG_SIGKILL.
To make things less confusing this also renames FORK_DEATHSIG to
FORK_DEATHSIG_SIGTERM to make clear it sends SIGTERM. We already had
FORK_DEATHSIG_SIGINT, hence this makes things nicely symmetric.
A bunch of users are switched over for FORK_DEATHSIG_SIGKILL where we
know it's safe to abort things abruptly. This should make some kernel
cases more robust, since we cannot get confused by signal masks or such.
While we are at it, also fix a bunch of bugs where we didn't take
FORK_DEATHSIG_SIGINT into account in safe_fork()
For a given PID and namespace type, this helper function gives the PID
of the leader of the namespace containing the given PID. Use this in
systemd-coredump instead of using the existing get_mount_namespace_leader.
This helper will be used again in a later commit.
This wraps glibc's clone() but deals with the 'stack' parameter in a
sensible way. Only supports invocations without CLONE_VM, i.e. when
child is a CoW copy of parent.
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.
If the flag is set, we mount /tmp/ in a way that is suitable for generators and
other quick jobs.
Unfortunately I had to move some code from shared/mount-util.c to
basic/mountpoint-util.c. The functions that are moved are very thin wrappers
around mount(2), so this doesn't actually change much in the code split between
libbasic and libshared.
Implications for the host would be weird if a private mount namespace is not
used, so assert on FORK_NEW_MOUNTNS when the flag is used.
I wanted to move saved_arg[cv] to process-util.c+h, but this causes problems:
process-util.h includes format-util.h which includes net/if.h, which conflicts
with linux/if.h. So we can't include process-util.h in some files.
But process-util.c is very long anyway, so it seems nice to create a new file.
rename_process(), invoked_as(), invoked_by_systemd(), and argv_looks_like_help()
which lived in process-util.c refer to saved_argc and saved_argv, so it seems
reasonable to move them to the new file too.
util.c is now empty, so it is removed. util.h remains.
Often the fds that shall stay around in the child shall be passed
to a process over execve(), hence add an option to explicitly disable
O_CLOEXEC on them in the child.
Library code should not call freeze(), this is something that should
only be done by "application code", so moving it into shared/ is appropriate.
The fallback to call _exit() is dropped: let's trust that the infinite loop
is infinite.
Currently it's only used in two places in src/shared/, so the function was
already included just once in compiled code. But it seems appropriate to
move it there anyway, because library code should have no need to fork
agents, so it doesn't belong in basic/.
We need a sorted list of fds to skip over when closing. We would allocate a
copy of the passed array to do the sort. But all callers construct a temporary
array to pass to us, so it is pointless to copy it again.
close_all_fds/safe_fork_full/namespace_fork/fork_agent are changed to pass
a non-const int array. I checked all users, and all callers are fine with
the array being sorted.
The function was returning some number (sometimes 1, sometimes the extent
of the range passed over to close_range(), ???). Anyway, all callers only
check for error, so let's return 0 on success.
The new flag is not used, except in tests, so no functional change yet.
This way, the command as shown can be copied-and-pasted into the shell
in more cases. For simple cases, shell quoting with "" is enough. But
$'' is needed when there are control characters in the command.
Since the new functionality is controlled by an option, this causes no change
in output yet, except tests.
The login in the old branch of !(flags & PROCESS_CMDLINE_QUOTE) is essentially
unmodified. But there is an important difference in behaviour: instead of
unconditionally reading the whole virtual file, we now read only 'max_columns'
bytes. This makes out code to write process lists quite a bit more efficient
when there are processes with long command lines.
argv[0] might be prefixed by a path, and we shouldn't get confused by
that. Hence provide a simple helper call that abstracts the checking
away, which we can use everywhere, and expose the same behaviour, even
if argv[0] is not set.
(While we are at it, port all other multi-call binaries over to the new
helper, too)
Follow-up for: d41a9e4fc1
"less" doesn't properly reset its terminal on SIGTERM, it does so only
on SIGINT. Let's thus configure SIGINT instead of SIGTERM.
I think this is something less should fix too, and clean up things
correctly on SIGTERM, too. However, given that we explicitly enable
SIGINT behaviour by passing "K" to $LESS I figure it makes sense if we
also send SIGINT instead of SIGTERM to match it.
Fixes: #16084
Lennart Poettering
Nick Rosbrook
Luca Boccassi
Yu Watanabe
Dan Streetman
Zbigniew Jędrzejewski-Szmek