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.
This used to be relevant since in old versions of glibc an internal
cache is maintained, while we might sidestep their invalidation
with raw_clone(). After glibc 2.25 getpid() is a trivial wrapper
for the syscall, and hence there's no need to have a separate
raw_getpid().
We always validate that the target value is below _LOG_TARGET_SINGLE_MAX
before acessing it, but we don't actually size the array like that.
let's fix that.
This doesn#t effectively change anything, but it makes things more
explicit what the limit here is.
glibc exports getdents64 syscall as is, but musl exports it as
posix_getdents(). Let's introduce a simple wrapper of posix_getdents().
Note, our baseline for glibc is 2.31. Hence, we can assume getdents64()
always defined when building with glibc.
To resolve conflict with sys/mount.h and linux/mount.h or linux/fs.h.
The conflict between sys/mount.h and linux/mount.h is resolved in
glibc-2.37 (774058d72942249f71d74e7f2b639f77184160a6), but our baseline
is still glibc-2.31. Also, even with the version or newer, still
sys/mount.h conflicts with linux/fs.h, which is included by
linux/btrfs.h.
This introduces our own implementation of sys/mount.h, that can be
simultaneously included with linux/mount.h and linux/fs.h. This also
imports linux/fs.h, linux/mount.h, and several other dependent headers.
The introduced sys/mount.h header itself may not be enough simple, but
by using the header, we can drop most of workarounds in other source files.
Nowadays, we define syscall numbers for newer syscalls.
Hence the conditions are not necessary.
This also adds several comments about when syscalls are introduced.
If a non-zero timeout is specified we should not bypass ppoll() even if
no fds are specified, since it will still act as a time based sleep in
that case.
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.
Lennart Poettering
Yu Watanabe
Mike Yuan
Daan De Meyer