Let's not leak details from src/shared and src/libsystemd into
src/basic, even though you can't actually do anything useful with
just forward declarations from src/shared.
The sd-forward.h header is put in src/libsystemd/sd-common as we
don't have a directory for shared internal headers for libsystemd
yet.
Let's also rename forward.h to basic-forward.h to keep things
self-explanatory.
Let's do a "soft" reset of the TTY when a ptyfwd session ends. This is a
good idea, in order to reset changes to the scrolling window that code
inside the session might have made. A "soft" reset will undo this.
While we are at it, make sure to output the ansi sequences for this
*after* terminating any half-written line, as that is still somewhat
contents of the session, even if it's augmented.
query_term_for_tty() is used in two places: in fixup_environment(),
which affects PID1 itself, and in build_environment(), which affects
spawned services. There is obviously some cost to the extra call,
but I think it's worthwhile to do it. When $TERM is set incorrectly,
basic output works OK, but then there are various annoying corner
cases. In particular, we get the support for color (or lack of it)
wrong, and when output is garbled, users are annoyed. Things like
text editors are almost certain to behave incorrectly. Testing in
test-terminal-util indicates that the time required to make a successful
query is on the order of a dozen microseconds, and an unsuccessful
query costs as much as our timeout, i.e. currently 1/3 ms. I think
this is an acceptable tradeoff.
No caching is used, because fixup_environment() is only called once,
and the other place in build_environment(), only affects services
which are connected to a tty, which is only a handful of services,
and often only started in special circumstances.
Fixes https://github.com/systemd/systemd/issues/36994.
C automatically casts a signed int to unsigned in binary operation with an
unsigned int. Thus that suffix is not useful. Also surrounding code doesn't use
it.
I noticed that systemd-tty-password-agent would time out when asked to
stop via SIGTERM, and eventually be killed, under some circumstances.
It took me a while but i figured out what was going on:
systemd-ask-pw-agent blocks SIGTERM because it wants async notifications
on SIGTERM via signalfd() to listen on. That mostly works great: except
for one case: if we actually get a pw query request, and hence need to
acquire the terminal: we issue open_terminal() in that case, but if the
terminal is used otherwsie we'll hang, and because SIGTERM is blocked
we'll hang and cannot exit cleanly.
Address that: optionally, in acquire_terminal() look for SIGTERM by
unblcking the signal mask via ppoll() while we wait.
So far we conditioned the logic that issues ansi sequences for resetting
the TTY based on whether something is a pty is not (under the assumption
we need no reset on ptys, since they are shortlived).
This is simply wrong though. The pty that a container getty is invoked
on is generally long-lived: as long as the container is up, and it will
be reused between getty instances/sessions all the time. In such a case
we really should reset properly.
Let's instead make the logic dependent on whether TERM is set to
anything other than "dumb". The previous commit made sure we always set
TERM in a sensible way in systemd-run, hence this
*explicit* logic sounds like a much better choice now, as it mea
let's convert the 2nd argumeng form a boolean to a proper flags
parameter. Doesn't change behaviour in anyway, but is more readable, and
prepares ground for adding more flags soon.
This adds TAB-based auto-completion to various fields we query from the
user, such as locale, keymap, timezone, group membership.
It makes it a lot easier to quickly iterate through firstboot without
typing too much.
This modernizes the function a bit, and adds some bits:
1. whether to show numbers before entries is now optional, and if they
are shown they are displayed in grey.
2. a common prefix can now be grayed out (later useful for completion
support)
3. some variables have been named to clarify their purpose
4. the table display dimensions can now be auto-sized (by specifying
SIZE_MAX and number of columns and column width)
1. Make the message a bit more visible, by adding ANSI color. This
matters in particular during boot, where the message otherwise might
be overprinted by other output
2. Let's turn off terminal echo so that whatever key is entered is not
made visible on screen, and we can handle newline and other keys
reasonably uniformly.
This makes use of the new TIOCGPTPEER pty ioctl() for directly opening a
PTY peer, without going via path names. This is nice because it closes a
race around allocating and opening the peer. And also has the nice
benefit that if we acquired an fd originating from some other
namespace/container, we can directly derive the peer fd from it, without
having to reenter the namespace again.
OSC sequences can be closed with one of three terminators:
1. ASCII code 7, aka BEL, aka ^G, aka \x07, aka \a
2. ASCII code 156, aka \x9c
2. Pair of ASCII code 27 followed by ASCII code 92, aka \x1b\x5c
Of these, in some corner case scenarios BEL makes problem (see #34604).
Hence switch away from that wherever we use it, and prefer the \x1b\x5c
instead. That's preferable over \x9c, since the latter is also a valid
UTF-8 codepoint. See discussion here for example:
https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda#the-escape-sequenceFixes: #34604
Let's provide a mechanism to select the number of screen columns for
rebreaking comments in Varlink IDL connected to a TTY, by honouring the
$COLUMNS env var then too. Previously we'd only honour when connected to
a TTY, but it's also useful otherwise for rebreaking ridiculously long
comments, hence honour it in this case too.
When pid 1 crashes, the getty unit for the console will happily keep
running which means we end up with two shells competing for the same
tty. Let's call vhangup on /dev/console to kill every other process
attached to the console before we spawn the crash shell. The getty
units have Restart=always but lucky for us, pid 1 just crashed in fire
and flames so it isn't actually able to restart the getty unit.
It doesn't really make sense to have that in dev-setup.c, which is
mostly about setting up /dev/, creating device nodes and stuff.
let's move it to the other stuff that deals with /dev/console's
peculiarities.
This is a lot of stuff, and sometimes quite wild, let's turn this into
its own header.
All stuff color-related that just generates sequences is now in
ansi-color.h (no .c file!), and everything more complex that
probes/ineracts with terminals remains in termina-util.[ch]
Let's put "terminal_" as prefix, like with the other reset calls, and
let's make clear that this only encapsulates the ioctl-based reset
logic, not the ANSI sequence based reset logic.
Lennart Poettering
Daan De Meyer
Zbigniew Jędrzejewski-Szmek
Yu Watanabe
Jelle van der Waa
Mike Yuan
Luca Boccassi
Michael Ferrari