This is mostly a strawman to get a discussion going regarding how to
communicate to terminal emulators such as ptyxis about run0 (and nspawn,
and vmspawn, and moe) and what it does.
It's hierarchical and I think still relatively simple.
/cc @chergert
Since kernel v4.14, more specifically, after the following four commits,
e46abbcc05b7263e071a387454901b6150957521
the maximum length of nftable identifiers are extended to 255.
Now, our kernel baseline is 5.4, hence we can freely use the extended
name length.
This also modernizes code a bit, and adds test cases.
Closes#36542.
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 has been depracted since v254 (2023). Let's kill it for
good now, it has been long enough with 2y. Noone has shown up who wants
to keep it. And given it doesn't work in SB world anyway, and is not
measured is quite problematic security wise.
Let's switch things around, and move the internals of safe_fork_full() into
pidref_safe_fork_full() and make safe_fork_full() a trivial wrapper on top
of pidref_safe_fork_full().
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.
CLONE_PIDFD was introduced in v5.2 and in sched.h in glibc-2.31 so
without this, building with older version fails with:
src/basic/raw-clone.h:41:108: error: 'CLONE_PIDFD' undeclared (first use in this function); did you mean 'CLONE_FILES'?
Added in 6140be90ec
However, when O_PATH fds are encountered we'd have to go by
/proc/self/fd/ still, since the kernel people are reluctant
to make the new syscalls work with them
(https://lore.kernel.org/linux-fsdevel/20250206-steril-raumplanung-733224062432@brauner/)
Hence getxattrat() and listxattrat() are not employed.
While at it, remove the discrepancy between path being NULL
and empty - I don't grok the "security issue" claimed earlier,
but nowadays even the kernel treats the two as identical:
e896474fe4
