This tries to address the "bind"/"unbind" uevent kernel API breakage, by
changing the semantics of device tags.
Previously, tags would be applied on uevents (and the database entries
they result in) only depending on the immediate context. This means that
if one uevent causes the tag to be set and the next to be unset, this
would immediately effect what apps would see and the database entries
would contain each time. This is problematic however, as tags are a
filtering concept, and if tags vanish then clients won't hence notice
when a device stops being relevant to them since not only the tags
disappear but immediately also the uevents for it are filtered including
the one necessary for the app to notice that the device lost its tag and
hence relevance.
With this change tags become "sticky". If a tag is applied is once
applied to a device it will stay in place forever, until the device is
removed. Tags can never be removed again. This means that an app
watching a specific set of devices by filtering for a tag is guaranteed
to not only see the events where the tag is set but also all follow-up
events where the tags might be removed again.
This change of behaviour is unfortunate, but is required due to the
kernel introducing new "bind" and "unbind" uevents that generally have
the effect that tags and properties disappear and apps hence don't
notice when a device looses relevance to it. "bind"/"unbind" events were
introduced in kernel 4.12, and are now used in more and more subsystems.
The introduction broke userspace widely, and this commit is an attempt
to provide a way for apps to deal with it.
While tags are now "sticky" a new automatic device property
CURRENT_TAGS is introduced (matching the existing TAGS property) that
always reflects the precise set of tags applied on the most recent
events. Thus, when subscribing to devices through tags, all devices that
ever had the tag put on them will be be seen, and by CURRENT_TAGS it may
be checked whether the device right at the moment matches the tag
requirements.
See: #7587#7018#8221
Previously, device_copy_properties() copies all properties to both
sd_device::properties and ::properties_db. Thus, on move uevent,
also tentative properties, e.g. DEVPATH or INTERFACE, are stored to
::properties_db, and saved to udev database.
This makes such tentative properties be copied to only ::properties,
and thus not saved to udev database.
Fixes#9426.
We had two very similar functions: device_read_db_aux and device_read_db,
and a number of wrappers for them:
device_read_db_aux
← device_read_db (in sd-device.c)
← all functions in sd-device.c, including sd_device_is_initialized
← device_read_db_force
← event_execute_rules_on_remove (in udev-event.c)
device_read_db (in device-private.c)
← functions in device_private.c (but not device_read_db_force):
device_get_devnode_{mode,uid,gid}
device_get_devlink_priority
device_get_watch_handle
device_clone_with_db
← called from udevadm, udev-{node,event,watch}.c
Before 7141e4f62c (sd-device: don't retry loading
uevent/db files more than once), the two implementations were the same. In that
commit, device_read_db_aux was changed. Those changes were reverted in the parent
commit, so the two implementations are now again the same except for superficial
differences. This commit removes device_read_db (in sd-device.c), and renames
device_read_db_aux to device_read_db_internal and makes everyone use this one
implementation. There should be no functional change.
This splits out a bunch of functions from fileio.c that have to do with
temporary files. Simply to make the header files a bit shorter, and to
group things more nicely.
No code changes, just some rearranging of source files.
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.
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.
Newer kernels will emit uevents with "bind" and "unbind" actions. These
uevents will be issued when driver is bound to or unbound from a device.
"Bind" events are helpful when device requires a firmware to operate
properly, and driver is unable to create a child device before firmware
is properly loaded.
For some reason systemd validates actions and drops the ones it does not
know, instead of passing them on through as old udev did, so we need to
explicitly teach it about them.
This prevents udev from reading the data after freeing it.
See https://github.com/systemd/systemd/issues/6040#issuecomment-306589836
==264== Invalid read of size 1
==264== at 0x4C2E112: strlen (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==264== by 0x5943EBD: strdup (in /usr/lib/libc-2.25.so)
==264== by 0x13E263: device_add_property_aux (sd-device.c:122)
==264== by 0x14788C: device_add_property_internal (sd-device.c:150)
==264== by 0x14788C: device_rename (device-private.c:786)
==264== by 0x120DB6: udev_device_rename (libudev-device-private.c:213)
==264== by 0x120DB6: udev_event_execute_rules (udev-event.c:895)
==264== by 0x120DB6: worker_spawn (udevd.c:456)
==264== by 0x1216E5: event_run (udevd.c:584)
==264== by 0x1216E5: event_queue_start (udevd.c:823)
==264== by 0x122213: on_uevent (udevd.c:927)
==264== by 0x141F2F: source_dispatch (sd-event.c:2272)
==264== by 0x142D52: sd_event_dispatch (sd-event.c:2631)
==264== by 0x142D52: sd_event_run (sd-event.c:2690)
==264== by 0x142D52: sd_event_loop (sd-event.c:2710)
==264== by 0x1159CB: run (udevd.c:1643)
==264== by 0x1159CB: main (udevd.c:1772)
==264== Address 0x7b251a0 is 0 bytes inside a block of size 5 free'd
==264== at 0x4C2C14B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==264== by 0x13E2A2: freep (alloc-util.h:57)
==264== by 0x13E2A2: device_add_property_aux (sd-device.c:111)
==264== by 0x147873: device_add_property_internal (sd-device.c:150)
==264== by 0x147873: device_rename (device-private.c:781)
==264== by 0x120DB6: udev_device_rename (libudev-device-private.c:213)
==264== by 0x120DB6: udev_event_execute_rules (udev-event.c:895)
==264== by 0x120DB6: worker_spawn (udevd.c:456)
==264== by 0x1216E5: event_run (udevd.c:584)
==264== by 0x1216E5: event_queue_start (udevd.c:823)
==264== by 0x122213: on_uevent (udevd.c:927)
==264== by 0x141F2F: source_dispatch (sd-event.c:2272)
==264== by 0x142D52: sd_event_dispatch (sd-event.c:2631)
==264== by 0x142D52: sd_event_run (sd-event.c:2690)
==264== by 0x142D52: sd_event_loop (sd-event.c:2710)
==264== by 0x1159CB: run (udevd.c:1643)
==264== by 0x1159CB: main (udevd.c:1772)
==264== Block was alloc'd at
==264== at 0x4C2AF1F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==264== by 0x5943EC9: strdup (in /usr/lib/libc-2.25.so)
==264== by 0x13E263: device_add_property_aux (sd-device.c:122)
==264== by 0x143B45: device_add_property_internal (sd-device.c:150)
==264== by 0x143B45: device_amend.lto_priv.235 (device-private.c:454)
==264== by 0x1387B7: device_append (device-private.c:516)
==264== by 0x1387B7: device_new_from_nulstr (device-private.c:620)
==264== by 0x1387B7: udev_device_new_from_nulstr (libudev-device-private.c:268)
==264== by 0x1387B7: udev_monitor_receive_device (libudev-monitor.c:682)
==264== by 0x11FC69: worker_spawn (udevd.c:509)
==264== by 0x1216E5: event_run (udevd.c:584)
==264== by 0x1216E5: event_queue_start (udevd.c:823)
==264== by 0x122213: on_uevent (udevd.c:927)
==264== by 0x141F2F: source_dispatch (sd-event.c:2272)
==264== by 0x142D52: sd_event_dispatch (sd-event.c:2631)
==264== by 0x142D52: sd_event_run (sd-event.c:2690)
==264== by 0x142D52: sd_event_loop (sd-event.c:2710)
==264== by 0x1159CB: run (udevd.c:1643)
==264== by 0x1159CB: main (udevd.c:1772)
==264==
Throughout the tree there's spurious use of spaces separating ++ and --
operators from their respective operands. Make ++ and -- operator
consistent with the majority of existing uses; discard the spaces.
GLIB has recently started to officially support the gcc cleanup
attribute in its public API, hence let's do the same for our APIs.
With this patch we'll define an xyz_unrefp() call for each public
xyz_unref() call, to make it easy to use inside a
__attribute__((cleanup())) expression. Then, all code is ported over to
make use of this.
The new calls are also documented in the man pages, with examples how to
use them (well, I only added docs where the _unref() call itself already
had docs, and the examples, only cover sd_bus_unrefp() and
sd_event_unrefp()).
This also renames sd_lldp_free() to sd_lldp_unref(), since that's how we
tend to call our destructors these days.
Note that this defines no public macro that wraps gcc's attribute and
makes it easier to use. While I think it's our duty in the library to
make our stuff easy to use, I figure it's not our duty to make gcc's own
features easy to use on its own. Most likely, client code which wants to
make use of this should define its own:
#define _cleanup_(function) __attribute__((cleanup(function)))
Or similar, to make the gcc feature easier to use.
Making this logic public has the benefit that we can remove three header
files whose only purpose was to define these functions internally.
See #2008.
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.
Some places invoked fflush() directly with their own manual error
checking, let's unify all that by using fflush_and_check().
This also unifies the general error paths of fflush()+rename() file
writers.
In device_update_properties_bufs(), the strv is built from pointers into the
single nul-terminated buf_nulstr string, to avoid allocating the key=value
strings twice. However, we must not do that while building and
GREEDY_REALLOC0()'ing buf_nulstr, as each time when this actually reallocates
memory the pointers we wrote into buf_strv so far become invalid.
So change the logic to first completely build the new buf_nulstr, and then
iterate over it to pick out the pointers to the individual key=value strings
for properties_strv.
This fixes invalid environment for udev callouts.
Yu Watanabe