TCSADRAIN means tcsetattr() will become blocking (waiting for ability to
write out queued bytes), which is problematic, if the referenced TTY is
dead for some reason.
Since all these calls just modify *input* parameters anyway (i.e. mostly
local echo, and canonical mode), forcing out queued output is kinda
pointless anyway, hence just don't do it: leave it in the queue and just
change the flags we want to change.
The tcsetattr(3) man page kinda hints that we want to use TCSANOW here,
because it documents for TCSADRAIN:
"This option should be used when changing parameters that affect
output."
Which one can read so that TCSADRAIN should not be used if it doesn't
affect output, which is the case here.
This probably fixes: #37854
Those static functions were written to support optional output params, but they
are only ever called with the output param set, and it doesn't make sense to
ever call them without the output param. Since those are internal functions,
drop this unused complexity.
tianocore does some weird shit with its terminal emulation and regular
fills half the terminal with grey background and then invokes us with
this not cleared up. Hence let us clear this up for it: as part of the
ansi sequence based reset let's position the cursor explicitly at the
beginning of the current line, and erase everything till the end of the
screen. This makes boot output in tianocore vms much much cleaner.
Note that this does *not* erase any terminal output *before* the cursor
position where we take over, because that typically contains valuable
information still we should not erase.
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.
So far we'd leave the cursor at the end of the Press any key to proceed
message as long as the user didn't type in anything yet, and generated
the newline only after.
Let's switch this around: let's output the newline before.
This should make boot-time output nicer since it means concurrent output
while we wait will start at the beginning of line, and not in the middle.
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.
tty_is_vc() is more often than not used for simple "categorization"
than validity check. E.g. in logind, we first recognize the tty
"looks like vc", and then use vtnr_from_tty() where range check
is performed and vtnr is extracted. In such cases, we want to reject
invalid vtnr from clients rather than silently carry on, hence
let's remove bound check in tty_is_vc().
Fixes#36166
Replaces #36167 and #36175
We never know, maybe there's some spurious POLLIN and read() will fail
with EAGAIN even though we saw POLLIN. Handle that.
(this can happen if we area not the only process reading from the tty,
or in case of hups and such).
Fixes: #35499
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
Various fixes:
1. Adds O_CLOEXEC for two socketpair()s where we forgot it.
2. Uses FORK_WAIT instead of manual wait_for_terminate_and_check()
invocations.
3. Prefix opaque NULL/0 arguments with comments what they are.
4. Add a banch of assert()s, and change flag validation in
open_terminal() to be assert() (since flags mistakes are programming
errors, not runtime errors).
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.
let's instead generate ENOTTY on our own. This is more correct with out
coding style (since we generally do not propagate errors via errno), and
also addresses #34039 as side effect. (#34039 really needs to be fixed
in musl though, too, this is just a work-around as side-effect).
Fixes: #34039
glibc returs EIO on ttys that are hung up. That's not really correct,
POSIX seems to disagree.
Work around this in our code, and turn this into a clean "1", since a
hung up tty doesn't stop being a tty just because it is hung up.
Background: https://github.com/systemd/systemd/pull/34039
Lennart Poettering
Yu Watanabe
Mike Yuan
Jelle van der Waa
Zbigniew Jędrzejewski-Szmek
Daan De Meyer
Luca Boccassi
Michael Ferrari