In particular:
- drop "when it is non-zero" to avoid implying that it can be called if the
queue is not empty.
- "has been created" sounds like something happened in parallel,
but what we really mean is that *this* particular object *was* created in a
certain way.
We maintain a queue of units and jobs that we are supposed to generate
change/new notifications for because they were either just created or
some of their property has changed. Let's throttle processing of this
queue a bit: as soon as > 1K of bus messages are queued for writing
let's skip processing the queue, and then recheck on the next
iteration again.
Moreover, never process more than 100 units in one go, return to the
event loop after that. Both limits together should put effective limits
on both space and time usage of the function, delaying further
operations until a later moment, when the queue is empty or the the
event loop is sufficiently idle again.
This should keep the number of generated messages much lower than
before on busy systems or where some client is hanging.
Note that this also means a bad client can slow down message dispatching
substantially for up to 90s if it likes to, for all clients. But that
should be acceptable as we only allow trusted bus clients, anyway.
Fixes: #8166
This is an optimization: there's no point in enqueuing unit and job
change notificiation signal messages into bus connection that aren't
fully set up yet.
This doesn't fix#8166 but should lower the load of messages enqueued
but not processed yet a bit.
There isn't much difference, but in general we prefer to use the standard
functions. glibc provides reallocarray since version 2.26.
I moved explicit_bzero is configure test to the bottom, so that the two stdlib
functions are at the bottom.
gcc warns about unitialized memory access because it notices that ssize_t which
is < 0 could be cast to positive int value. We know that this can't really
happen because only -1 can be returned, but OTOH, in principle a large
*positive* value cannot be cast properly. This is unlikely too, since xattrs
cannot be too large, but it seems cleaner to just use a size_t to return the
value and avoid the cast altoghter. This makes the code simpler and gcc is
happy too.
The following warning goes away:
[113/1502] Compiling C object 'src/basic/basic@sta/xattr-util.c.o'.
In file included from ../src/basic/alloc-util.h:28:0,
from ../src/basic/xattr-util.c:30:
../src/basic/xattr-util.c: In function ‘fd_getcrtime_at’:
../src/basic/macro.h:207:60: warning: ‘b’ may be used uninitialized in this function [-Wmaybe-uninitialized]
UNIQ_T(A,aq) < UNIQ_T(B,bq) ? UNIQ_T(A,aq) : UNIQ_T(B,bq); \
^
../src/basic/xattr-util.c:155:19: note: ‘b’ was declared here
usec_t a, b;
^
$ sudo systemd-run -p RootDirectory=/usr -E LD_LIBRARY_PATH=/lib/systemd/ -E SYSTEMD_LOG_LEVEL=debug /bin/systemd-detect-virt
Before
systemd-detect-virt[18498]: No virtualization found in DMI
systemd-detect-virt[18498]: No virtualization found in CPUID
systemd-detect-virt[18498]: Virtualization XEN not found, /proc/xen does not exist
systemd-detect-virt[18498]: This platform does not support /proc/device-tree
systemd-detect-virt[18498]: Failed to check for virtualization: No such file or directory
The first four lines are at debug level, so the user would only see that last
one usually, which is not very enlightening.
This now becomes:
systemd-detect-virt[21172]: No virtualization found in DMI
systemd-detect-virt[21172]: No virtualization found in CPUID
systemd-detect-virt[21172]: Virtualization XEN not found, /proc/xen does not exist
systemd-detect-virt[21172]: This platform does not support /proc/device-tree
systemd-detect-virt[21172]: /proc/cpuinfo not found, assuming no UML virtualization.
systemd-detect-virt[21172]: This platform does not support /proc/sysinfo
systemd-detect-virt[21172]: Found VM virtualization none
systemd-detect-virt[21172]: none
We do more checks, which is good too.
Then it can be used in the asserts in logging functions without causing
infinite recursion. The error is just printed to stderr, it should be
good enough for the common case.
gcc-8 throws an error if it knows snprintf might truncate output and the
return value is ignored:
../src/udev/udev-builtin-net_id.c: In function 'dev_pci_slot':
../src/udev/udev-builtin-net_id.c:297:47: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size between 0 and 4095 [-Werror=format-truncation=]
snprintf(str, sizeof str, "%s/%s/address", slots, dent->d_name);
^~
../src/udev/udev-builtin-net_id.c:297:17: note: 'snprintf' output between 10 and 4360 bytes into a destination of size 4096
snprintf(str, sizeof str, "%s/%s/address", slots, dent->d_name);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
Let's check all return values. This actually makes the code better, because there's
no point in trying to open a file when the name has been truncated, etc.
If log_do_header() was called with overly long parameters, it'd generate
improper output. Essentially, it'd be truncated at random point, in particular
missing a newline at the end, so it'd run with the next field, usually MESSAGE=.
log_do_header is called with parameters from compiled code (file name, lien
nubmer, etc), so in practice this was unlikely to ever be a problem, but it is
possible. In particular, if systemd was compiled from sources in some deeply
nested directory (which happens for example in mock and other build roots), the
filename could be very long.
As a safety measure, let's truncate all parameters to 256 bytes. So we have
5 fields which are 256 bytes (plus the field name prefix), and a few other
fields with fixed width. This must always fit in the 2048 byte buffer.
I don't think there's much gain in calculating the required length precisely,
since it's a lot of fields and a few bytes allocated on the stack don't matter.
log_dispatch_internal has only one caller where the extra_field/extra
params are not null: log_unit_full. When log_unit_full() was called,
when we got to log_dispatch_internal, our header would look like this:
PRIORITY=7
SYSLOG_FACILITY=3
CODE_FILE=../src/core/manager.c
CODE_LINE=2145
CODE_FUNC=manager_invoke_sigchld_event
USER_UNIT=gnome-terminal-server.service
65dffa7a3b984a6d9a46f0b8fb57710bUSER_INVOCATION_ID=
SYSLOG_IDENTIFIER=systemd
It took me a while to understand why I'm not seeing mangled messages in the
journal (after all, "" is a valid rvalue for log messages). The answer is that
journald rejects any field name which starts with a digit, and the MESSAGE_ID
that was used here starts with a digit. Hence, those lines would be silently
filtered out.
If a touchpad has MT axes only but not ABS_X/ABS_Y (DualShock 4 controller),
then we hit both the conditions is_touchpad and the later check for
!has_abs_axes here, assigning is_mouse and ID_INPUT_MOUSE later.
This is a bug, we historically only assigned either of of the pointing device
tags ID_INPUT_MOUSE/TOUCHPAD/JOYSTICK/TOUCHSCREEN, never multiple of them.
Note that we cannot just check for has_abs_axes and has_mt_coordinates because
the apple touch mouse has both. We really need to check if the device has
already been assigned something else.
https://bugs.freedesktop.org/show_bug.cgi?id=105050
