Properties marked this way really shouldn't be sent around willy-nilly,
that's what the flag is about, hence exclude it from InterfacesAdded
signals (and in fact anything that is a signal).
This allows marking messages that contain "sensitive" data with a flag.
If it's set then the messages are erased from memory when the message is
freed.
Similar, a flag may be set on vtable entries: incoming/outgoing message
matching the entry will then automatically be flagged this way.
This is supposed to be an easy method to mark messages containing
potentially sensitive data (such as passwords) for proper destruction.
(Note that this of course is only is as safe as the broker in between is
doing something similar. But let's at least not be the ones at fault
here.)
"Unknown interface or property." →
"Unknown interface org.freedesktop.network1.Link or property BitRates."
(I don't think the quotes are necessary. Dbus names have pretty strict rules.)
test-bus-introspect is also applied to the tables from test-bus-vtable.c.
test-bus-vtable.c is also used as C++ sources to produce test-bus-vtable-cc,
and our hashmap headers are not C++ compatible. So let's do the introspection
part only in the C version.
Just moving code around, in preparation to allow the content creation
part to be used in other places.
On the surface of things, introspect_path() should be in bus-introspect.c, but
introspect_path() uses many static helper functions in bus-objects.c, so moving
it would require all of them to be exposed, which is too much trouble.
test-bus-introspect is updated to actually write the closing bracket.
We would check the size of sd_bus_vtable entries, requring one of the two known
sizes. But we should be able to extend the structure in the future, by adding
new fields, without breaking backwards compatiblity.
Incidentally, this check was what caused -EINVAL failures before, when programs
were compiled with systemd-242 and run with older libsystemd.
In 856ad2a86b sd_bus_add_object_vtable() and
sd_bus_add_fallback_vtable() were changed to take an updated sd_bus_vtable[]
array with additional 'features' and 'names' fields in the union.
The commit tried to check whether the old or the new table format is used, by
looking at the vtable[0].x.start.element_size field, on the assumption that the
added fields caused the structure size to grow. Unfortunately, this assumption
was false, and on arm32 (at least), the structure size is unchanged.
In libsystemd we use symbol versioning and a major.minor.patch semantic
versioning of the library name (major equals the number in the so-name). When
systemd-242 was released, the minor number was (correctly) bumped, but this is
not enough, because no new symbols were added or symbol versions changed. This
means that programs compiled with the new systemd headers and library could be
successfully linked to older versions of the library. For example rpm only
looks at the so-name and the list of versioned symbols, completely ignoring the
major.minor numbers in the library name. But the older library does not
understand the new vtable format, and would return -EINVAL after failing the
size check (on those architectures where the structure size did change, i.e.
all 64 bit architectures).
To force new libsystemd (with the functions that take the updated
sd_bus_vtable[] format) to be used, let's pull in a dummy symbol from the table
definition. This is a bit wasteful, because a dummy pointer has to be stored,
but the effect is negligible. In particular, the pointer doesn't even change
the size of the structure because if fits in an unused area in the union.
The number stored in the new unsigned integer is not checked anywhere. If the
symbol exists, we already know we have the new version of the library, so an
additional check would not tell us anything.
An alternative would be to make sd_bus_add_{object,fallback}_vtable() versioned
symbols, using .symver linker annotations. We would provide
sd_bus_add_{object,fallback}_vtable@LIBSYSTEMD_221 (for backwards
compatibility) and e.g. sd_bus_add_{object,fallback}_vtable@@LIBSYSTEMD_242
(the default) with the new implementation. This would work too, but is more
work. We would have to version at least those two functions. And it turns out
that the .symver linker instructions have to located in the same compilation
unit as the function being annotated. We first compile libsystemd.a, and then
link it into libsystemd.so and various other targets, including
libsystemd-shared.so, and the nss modules. If the .symver annotations were
placed next to the function definitions (in bus-object.c), they would influence
all targets that link libsystemd.a, and cause problems, because those functions
should not be exported there. To export them only in libsystemd.so, compilation
would have to be rearranged, so that the functions exported in libsystemd.so
would not be present in libsystemd.a, but a separate compilation unit containg
them and the .symver annotations would be linked solely into libsystemd.so.
This is certainly possible, but more work than the approach in this patch.
856ad2a86b has one more issue: it relies on the
undefined fields in sd_bus_vtable[] array to be zeros. But the structure
contains a union, and fields of the union do not have to be zero-initalized by
the compiler. This means that potentially, we could have garbarge values there,
for example when reading the old vtable format definition from the new function
implementation. In practice this should not be an issue at all, because vtable
definitions are static data and are placed in the ro-data section, which is
fully initalized, so we know that those undefined areas will be zero. Things
would be different if somebody defined the vtable array on the heap or on the
stack. Let's just document that they should zero-intialize the unused areas
in this case.
The symbol checking code had to be updated because otherwise gcc warns about a
cast from unsigned to a pointer.
Fixes#12036.
../../../src/systemd/src/libsystemd/sd-bus/bus-objects.c: In function ‘add_object_vtable_internal’:
../../../src/systemd/src/basic/macro.h:423:19: error: duplicate case value
Paths are limited to BUS_PATH_SIZE_MAX but the maximum size is anyway too big
to be allocated on the stack, so let's switch to the heap where there is a
clear way to understand if the allocation fails.
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.
Let's always write "1 << 0", "1 << 1" and so on, except where we need
more than 31 flag bits, where we write "UINT64(1) << 0", and so on to force
64bit values.
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.
This macro will read a pointer of any type, return it, and set the
pointer to NULL. This is useful as an explicit concept of passing
ownership of a memory area between pointers.
This takes inspiration from Rust:
https://doc.rust-lang.org/std/option/enum.Option.html#method.take
and was suggested by Alan Jenkins (@sourcejedi).
It drops ~160 lines of code from our codebase, which makes me like it.
Also, I think it clarifies passing of ownership, and thus helps
readability a bit (at least for the initiated who know the new macro)
Currently, sd-bus supports the ability to have thread-local default busses.
However, this is less useful than it can be since all functions which
require an sd_bus* as input require the caller to pass it. This patch adds
a new macro which allows the developer to pass a constant SD_BUS_DEFAULT,
SD_BUS_DEFAULT_USER or SD_BUS_DEFAULT_SYSTEM instead. This reduces work for
the caller.
For example:
r = sd_bus_default(&bus);
r = sd_bus_call_method(bus, ...);
sd_bus_unref(bus);
Becomes:
r = sd_bus_call_method(SD_BUS_DEFAULT, ...);
If the specified thread-local default bus does not exist, the function
calls will return -ENOPKG. No bus will ever be implicitly created.
Let's replace usage of fputc_unlocked() and friends by __fsetlocking(f,
FSETLOCKING_BYCALLER). This turns off locking for the entire FILE*,
instead of doing individual per-call decision whether to use normal
calls or _unlocked() calls.
This has various benefits:
1. It's easier to read and easier not to forget
2. It's more comprehensive, as fprintf() and friends are covered too
(as these functions have no _unlocked() counterpart)
3. Philosophically, it's a bit more correct, because it's more a
property of the file handle really whether we ever pass it on to another
thread, not of the operations we then apply to it.
This patch reworks all pieces of codes that so far used fxyz_unlocked()
calls to use __fsetlocking() instead. It also reworks all places that
use open_memstream(), i.e. use stdio FILE* for string manipulations.
Note that this in some way a revert of 4b61c87511.
It's confusing to use a single void* to store data with two different
types, i.e. a userdata value which is safe to pass to ->find(), and a
userdata value which identifies the found object.
Name the latter `found_u`. This naming treats (!c->find) as a degenerate
case. (I.e. at that point, we know the object has already been found :).
Before this commit, if you run `loginctl user-status` from
debug-shell.service (and you have no login sessions for root), you always
see this output:
0
Linger: no
because Properties.GetAll is returning success but without any properties,
when the only find() callback had returned 0 to mean "no object found".
After:
Could not get properties: Unknown object:
'/org/freedesktop/login1/user/self'
BTW I have a fix for more user-friendly messages from logind in this case.
It is pending in my local branch for #6829 "fix `loginctl enable-linger`".
As a follow-up for db3f45e2d2 let's do the
same for all other cases where we create a FILE* with local scope and
know that no other threads hence can have access to it.
For most cases this shouldn't change much really, but this should speed
dbus introspection and calender time formatting up a bit.
Previously we'd propagate errors returned by user callbacks configured
in vtables back to the users only for method handlers and property
get/set handlers. This does the same for child enumeration and when we
check whether a fallback unit exists.
Without this the failure will be treated as a non-recoverable connection
error and result in connection termination.
Fixes: #6059
We already report builtin interfaces with InterfacesAdded and InterfacesRemoved. However,
we never reported them in GetManagedObjects(). This might end up confusing callers that
want to use those interfaces (or simply rely on the interface count to be coherent).
Report the builtins for all objects that are queried.
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.
All our hash functions are based on siphash24(), factor out
siphash_init() and siphash24_finalize() and pass the siphash
state to the hash functions rather than the hash key.
This simplifies the hash functions, and in particular makes
composition simpler as calling siphash24_compress() repeatedly
on separate chunks of input has the same effect as first
concatenating the input and then calling siphash23_compress()
on the result.
Currently, our introspection data looks like this:
<node>
<interface name="org.freedesktop.DBus.Peer">
...
</interface>
<interface name="org.freedesktop.DBus.Introspectable">
...
</interface>
<interface name="org.freedesktop.DBus.Properties">
...
</interface>
<node name="org"/>
<node name="org/freedesktop"/>
<node name="org/freedesktop/login1"/>
<node name="org/freedesktop/login1/user"/>
<node name="org/freedesktop/login1/user/self"/>
<node name="org/freedesktop/login1/user/_1000"/>
<node name="org/freedesktop/login1/seat"/>
<node name="org/freedesktop/login1/seat/self"/>
<node name="org/freedesktop/login1/seat/seat0"/>
<node name="org/freedesktop/login1/session"/>
<node name="org/freedesktop/login1/session/self"/>
<node name="org/freedesktop/login1/session/c1"/>
</node>
(ordered alphabetically for better visibility)
This is grossly incorrect. The spec says that we're allowed to return
non-directed children, however, it does not allow us to return data
recursively in multiple parents. If we return "org", then we must not
return anything else that starts with "org/".
It is unclear, whether we can include child-nodes as a tree. Moreover, it
is usually not what the caller wants. Hence, this patch changes sd-bus to
never return introspection data recursively. Instead, only a single
child-layer is returned.
This patch relies on enumerators to never return hierarchies. If someone
registers an enumerator via sd_bus_add_enumerator, they better register
sub-enumerators if they support *TRUE* hierarchies. Each enumerator is
treated as a single layer and not filtered.
Enumerators are still allowed to return nested data. However, that data
is still required to be a single hierarchy. For instance, returning
"/org/foo" and "/com/bar" is fine, but including "/com" or "/org" in that
dataset is not.
This should be the default for enumerators and I see no reason to filter
in sd-bus. Moreover, filtering that data-set would require to sort the
strv by path and then do prefix-filtering. This is O(n log n), which
would be fine, but still better to avoid.
Fixes#664.
This reverts commit d4d00020d6. The idea of
the commit is broken and needs to be reworked. We really cannot reduce
the bus-addresses to a single address. We always will have systemd with
native clients and legacy clients at the same time, so we also need both
addresses at the same time.
This allows marking properties as "explicit". Properties marked like
this are included in the introspection, but are avoided in GetAll()
property queries, PropertiesChanged() signals and in in GetManaged()
object manager calls and InterfacesAdded() signals.
Expensive properties may be marked that way, and they will be
retrievable when explicitly being requested, but never in "blanket"
all-property queries and signals.
This flag may be combined with the flags for "const" and
"emit-validation" properties, but not with "emit-validation", as that
is only useful for properties whose value shall be sent in "blanket"
all-property signals.
The "explicit" flag is also exposed in the introspection data via a new
annotation.
