NMSetting internally already tracked a list of all proper GObject properties
and D-Bus-only properties.
Rework the tracking of the list, so that:
- instead of attaching the data to the GType of the setting via
g_type_set_qdata(), it is tracked in a static array indexed by
NMMetaSettingType. This allows to find the setting-data by simple
pointer arithmetic, instead of taking a look and iterating (like
g_type_set_qdata() does).
Note, that this is still thread safe, because the static table entry is
initialized in the class-init function with _nm_setting_class_commit().
And it only accessed by following a NMSettingClass instance, thus
the class constructor already ran (maybe not for all setting classes,
but for the particular one that we look up).
I think this makes initialization of the metadata simpler to
understand.
Previously, in a first phase each class would attach the metadata
to the GType as setting_property_overrides_quark(). Then during
nm_setting_class_ensure_properties() it would merge them and
set as setting_properties_quark(). Now, during the first phase,
we only incrementally build a properties_override GArray, which
we finally hand over during nm_setting_class_commit().
- sort the property infos by name and do binary search.
Also expose this meta data types as internal API in nm-setting-private.h.
While not accessed yet, it can prove beneficial, to have direct (internal)
access to these structures.
Also, rename NMSettingProperty to NMSettInfoProperty to use a distinct
naming scheme. We already have 40+ subclasses of NMSetting that are called
NMSetting*. Likewise, NMMetaSetting* is heavily used already. So, choose a
new, distinct name.
Previously, each (non abstract) NMSetting class had to register
its name and priority via _nm_register_setting().
Note, that libnm-core.la already links against "nm-meta-setting.c",
which also redundantly keeps track of the settings name and gtype
as well.
Re-use NMMetaSettingInfo also in libnm-core.la, to track this meta
data.
The goal is to get rid of private data structures that track
meta data about NMSetting classes. In this case, "registered_settings"
hash. Instead, we should have one place where all this meta data
is tracked. This was, it is also accessible as internal API,
which can be useful (for keyfile).
Note that NMSettingClass has some overlap with NMMetaSettingInfo.
One difference is, that NMMetaSettingInfo is const, while NMSettingClass
is only initialized during the class_init() method. Appart from that,
it's mostly a matter of taste, whether we attach meta data to
NMSettingClass, to NMMetaSettingInfo, or to a static-array indexed
by NMMetaSettingType.
Note, that previously, _nm_register_setting() was private API. That
means, no user could subclass a functioning NMSetting instance. The same
is still true: NMMetaSettingInfo is internal API and users cannot access
it to create their own NMSetting subclasses. But that is almost desired.
libnm is not designed, to be extensible via subclassing, nor is it
clear why that would be a useful thing to do. One day, we should remove
the NMSetting and NMSettingClass definitions from public headers. Their
only use is subclassing the types, which however does not work.
While libnm-core was linking already against nm-meta-setting.c,
nm_meta_setting_infos was unreferenced. So, this change increases
the binary size of libnm and NetworkManager (1032 bytes). Note however
that roughly the same information was previously allocated at runtime.
- Don't use @parent_class name. This local variable (and @object_class) is
the class instance up-cast to the pointer types of the parents. The point
here is not that it is the direct parent. The point is, that it's the
NMSettingClass type.
Also, it can only be used inconsistently, in face of NMSettingIP4Config,
who's parent type is NMSettingIPConfig. Clearly, inside
nm-setting-ip4-config.c we wouldn't want to use the "parent_class"
name. Consistently rename @parent_class to @setting_class.
- Also rename the pointer to the own class to @klass. "setting_class" is also the
wrong name for that, because the right name would be something like
"setting_6lowpan_class".
However, "klass" is preferred over the latter, because we commonly create new
GObject implementations by copying an existing one. Generic names like "klass"
and "self" inside a type implementation make that simpler.
- drop useless comments like
/* virtual functions */
/* Properties */
It's better to logically and visually structure the code, and avoid trival
remarks about that. They only end up being used inconsistently. If you
even need a stronger visual separator, then an 80 char /****/ line
should be preferred.
constructor functions are ugly, because code is running before
main() starts. Instead, as the registration code for NMSetting types
is insid the GType constructor, we just need to ensure at the
right place, that the GType was created.
The right place here is _register_settings_ensure_inited(), because
that is called before we need the registration information.
Kernel recently got support for exposing TUN/TAP information on netlink
[1], [2], [3]. Add support for it to the platform cache.
The advantage of using netlink is that querying sysctl bypasses the
order of events of the netlink socket. It is out of sync and racy. For
example, platform cache might still think that a tun device exists, but
a subsequent lookup at sysfs might fail because the device was deleted
in the meantime. Another point is, that we don't get change
notifications via sysctl and that it requires various extra syscalls
to read the device information. If the tun information is present on
netlink, put it into the cache. This bypasses checking sysctl while
we keep looking at sysctl for backward compatibility until we require
support from kernel.
Notes:
- we had two link types NM_LINK_TYPE_TAP and NM_LINK_TYPE_TUN. This
deviates from the model of how kernel treats TUN/TAP devices, which
makes it more complicated. The link type of a NMPlatformLink instance
should match what kernel thinks about the device. Point in case,
when parsing RTM_NETLINK messages, we very early need to determine
the link type (_linktype_get_type()). However, to determine the
type of a TUN/TAP at that point, we need to look into nested
netlink attributes which in turn depend on the type (IFLA_INFO_KIND
and IFLA_INFO_DATA), or even worse, we would need to look into
sysctl for older kernel vesions. Now, the TUN/TAP type is a property
of the link type NM_LINK_TYPE_TUN, instead of determining two
different link types.
- various parts of the API (both kernel's sysctl vs. netlink) and
NMDeviceTun vs. NMSettingTun disagree whether the PI is positive
(NM_SETTING_TUN_PI, IFLA_TUN_PI, NMPlatformLnkTun.pi) or inverted
(NM_DEVICE_TUN_NO_PI, IFF_NO_PI). There is no consistent way,
but prefer the positive form for internal API at NMPlatformLnkTun.pi.
- previously NMDeviceTun.mode could not change after initializing
the object. Allow for that to happen, because forcing some properties
that are reported by kernel to not change is wrong, in case they
might change. Of course, in practice kernel doesn't allow the device
to ever change its type, but the type property of the NMDeviceTun
should not make that assumption, because, if it actually changes, what
would it mean?
- note that as of now, new netlink API is not yet merged to mainline Linus
tree. Shortcut _parse_lnk_tun() to not accidentally use unstable API
for now.
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1277457
[2] https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=1ec010e705934c8acbe7dbf31afc81e60e3d828b
[3] https://git.kernel.org/pub/scm/network/iproute2/iproute2-next.git/commit/?id=118eda77d6602616bc523a17ee45171e879d1818https://bugzilla.redhat.com/show_bug.cgi?id=1547213https://github.com/NetworkManager/NetworkManager/pull/77
- All internal source files (except "examples", which are not internal)
should include "config.h" first. As also all internal source
files should include "nm-default.h", let "config.h" be included
by "nm-default.h" and include "nm-default.h" as first in every
source file.
We already wanted to include "nm-default.h" before other headers
because it might contains some fixes (like "nm-glib.h" compatibility)
that is required first.
- After including "nm-default.h", we optinally allow for including the
corresponding header file for the source file at hand. The idea
is to ensure that each header file is self contained.
- Don't include "config.h" or "nm-default.h" in any header file
(except "nm-sd-adapt.h"). Public headers anyway must not include
these headers, and internal headers are never included after
"nm-default.h", as of the first previous point.
- Include all internal headers with quotes instead of angle brackets.
In practice it doesn't matter, because in our public headers we must
include other headers with angle brackets. As we use our public
headers also to compile our interal source files, effectively the
result must be the same. Still do it for consistency.
- Except for <config.h> itself. Include it with angle brackets as suggested by
https://www.gnu.org/software/autoconf/manual/autoconf.html#Configuration-Headers
