Right now systemd-update-utmp.service would fail on read-only /var because
it was not able to write the wtmp record. But it still writes the utmp
record just fine, so runtime information is OK. I don't think we need to
make too much fuss about not being able to save wtmp info.
Prompted by the discussion on #16110, let's migrate more code to
fd_wait_for_event().
This only leaves 7 places where we call into poll()/poll() directly in
our entire codebase. (one of which is fd_wait_for_event() itself)
poll() sets POLLNVAL inside of the poll structures if an invalid fd is
passed. So far we generally didn't check for that, thus not taking
notice of the error. Given that this specific kind of error is generally
indication of a programming error, and given that our code is embedded
into our projects via NSS or because people link against our library,
let's explicitly check for this and convert it to EBADF.
(I ran into a busy loop because of this missing check when some of my
test code accidentally closed an fd it shouldn't close, so this is a
real thing)
Unfortunately the warning must be known, or otherwise the pragma generates a
warning or an error. So let's do a meson check for it.
Is it worth doing this to silence the warning? I think so, because apparently
the warning was already emitted by gcc-8.1, and with the recent push in gcc to
catch more such cases, we'll most likely only get more of those.
The fact that strncpy does the truncation is the whole point here, and gcc
shouldn't warn about this. We can avoid the warning and simplify the
whole procedure by directly copying the interesting part.
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
Double newlines (i.e. one empty lines) are great to structure code. But
let's avoid triple newlines (i.e. two empty lines), quadruple newlines,
quintuple newlines, …, that's just spurious whitespace.
It's an easy way to drop 121 lines of code, and keeps the coding style
of our sources a bit tigther.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
Apparently O_NONBLOCK is the modern name used in most documentation and
for most cases in our sources. Let's hence replace the old alias
O_NDELAY and stick to O_NONBLOCK everywhere.
There are more than enough calls doing string manipulations to deserve
its own files, hence do something about it.
This patch also sorts the #include blocks of all files that needed to be
updated, according to the sorting suggestions from CODING_STYLE. Since
pretty much every file needs our string manipulation functions this
effectively means that most files have sorted #include blocks now.
Also touches a few unrelated include files.
When generating utmp/wtmp entries, optionally add both LOGIN_PROCESS and
INIT_PROCESS entries or even all three of LOGIN_PROCESS, INIT_PROCESS
and USER_PROCESS entries, instead of just a single INIT_PROCESS entry.
With this change systemd may be used to not only invoke a getty directly
in a SysV-compliant way but alternatively also a login(1) implementation
or even forego getty and login entirely, and invoke arbitrary shells in
a way that they appear in who(1) or w(1).
This is preparation for a later commit that adds a "machinectl shell"
operation to invoke a shell in a container, in a way that is compatible
with who(1) and w(1).
Instead of looking up the tty from STDIN, let utmp_wall() take an argument
to specify an origin tty for the wall message. Only if that argument is
NULL do the STDIN lookup.
Also add an void *userdata argument that is handed back to the callback
function.
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
include-what-you-use automatically does this and it makes finding
unnecessary harder to spot. The only content of poll.h is a include
of sys/poll.h so should be harmless.
utmp_wall() now takes an optional argument 'username_override' which
allows the caller to override the username shown on wall messages.
journald will use this to inform users that its wall messages comes from
'systemd-journald'.
The only problem is that libgen.h #defines basename to point to it's
own broken implementation instead of the GNU one. This can be fixed
by #undefining basename.
I'm assuming that it's fine if a _const_ or _pure_ function
calls assert. It is assumed that the assert won't trigger,
and even if it does, it can only trigger on the first call
with a given set of parameters, and we don't care if the
compiler moves the order of calls.
Before, we would initialize many fields twice: first
by filling the structure with zeros, and then a second
time with the real values. We can let the compiler do
the job for us, avoiding one copy.
A downside of this patch is that text gets slightly
bigger. This is because all zero() calls are effectively
inlined:
$ size build/.libs/systemd
text data bss dec hex filename
before 897737 107300 2560 1007597 f5fed build/.libs/systemd
after 897873 107300 2560 1007733 f6075 build/.libs/systemd
… actually less than 1‰.
A few asserts that the parameter is not null had to be removed. I
don't think this changes much, because first, it is quite unlikely
for the assert to fail, and second, an immediate SEGV is almost as
good as an assert.
systemd-199/src/shared/utmp-wtmp.c:228: buffer_size_warning: Calling
strncpy with a maximum size argument of 32 bytes on destination array
"store.ut_line" of size 32 bytes might leave the destination string
unterminated.
The destination string is unterminated on purpose, but we must
remember that.
Yu Watanabe