Use a static table with all the typing information, rather than repeated
switch statements. This should make it a lot simpler to add new types.
We need to keep all the type info to be able to create containers
without exposing their implementation details to the users of the library.
As a freebee we verify the types of appended/read attributes.
The API is extended to nicely deal with unions of container types.
The object is not currently used, so just drop the refenence. If/when we end up
using the object in the future, we must make sure to deal with possible mutual
references between rtnl busses and their queued messages; as is done in sd-bus.
Added support for tunneling netlink attrributes (ipip, gre, sit).
These works with kernel module ipip, gre and sit . The test cases are
moved to a separate file and manual test as well because they require
respective kernel modules as well.
Extend rta_offset_tb into a stack of offset tables, one for each parent of the
current container, and make sd_rtnl_message_{enter,exit}_container() pop/push
to this stack.
Also make sd_rtnl_message_rewind() parse the top-level container, and use this
when reading a message from the socket.
This changes the API by dropping the now redundant sd_rtnl_message_read()
method.
safe_close_pair() is more like safe_close(), except that it handles
pairs of fds, and doesn't make and misleading allusion, as it works
similarly well for socketpairs() as for pipe()s...
If you allocate a message with bus==NULL and then unref the main bus,
it will free your message underneath and your program will go boom!
To fix that, we really need to figure out what the semantics for
self-references (m->bus) should be and when/where/what accesses are
actually allowed.
Same is true for the pseudo-thread-safety we employ..
In sd_bus_unref() we check for self-reference loops and destruct our
queues in case we're the only reference holders. However, we do _not_
modify our own ref-count, thus effectively causing the
message-destructions to enter with the same reference count as we did.
The only reason this doesn't cause an endless recursion (or trigger
assert(m->n_ref > 0) in sd_bus_message_unref()) is the fact that we
decrease queue-counters _before_ calling _unref(). That's not obvious at
all, so add a big fat note in bus_reset_queues() to everyone touching that
code.
Like sd-bus, sd-rtnl can have self-references through queued messages. In
particular, each queued message has the following self-ref loop:
rtnl->wqueue[i]->rtnl == rtnl
Same is true for "rqueue".
When sd_rtnl_unref() gets called, we must therefore make sure we correctly
consider each self-reference when deciding to destroy the object. For each
queued message, there _might_ be one ref. However, rtnl-messages can be
created _without_ a bus-reference, therefore we need to verify the
actually required ref-count.
Once we know exactly how many self-refs exist, and we verified none of the
queued messages has external references, we can destruct the object.
We must immediately drop our own reference, then flush all queues and
destroy the bus object. Otherwise, each sd_rtnl_message_unref() call would
recurse into the same destruction logic as they enter with the same
rtnl-refcnt.
Note: We really should verify _all_ queued messages have m->rtnl set to
the bus they're queued on. If that's given, we can change:
if (REFCNT_GET(rtnl->n_ref) <= refs)
to
if (REFCNT_GET(rtnl->n_ref) == refs)
and thus avoid recalculating the required refs for each message we
remove from the queue during destruction.
Add a new config 'Activating' directive which denotes whether a busname
is actually registered on the bus. It defaults to 'yes'.
If set to 'no', the .busname unit only uploads policy, which will remain
active as long as the unit is running.
This makes sure we don't mishandle if developers specificy a different
AcceptFileDescriptors= setting in .busname units then they set for the
bus connection in the activated program.
AcceptFD= defaults to true, thus making sure that by default fd passing
is enabled for all activatable names. Since for normal bus connections
fd passing is enabled too by default this makes sure fd passing works
correctly regardless whether a service is already activated or not.
Making this configurable on both busname units and in bus connections is
messy, but unavoidable since busnames are established and may queue
messages before the connection feature negotiation is done by the
service eventually activated. Conversely, feature negotiation on bus
connections takes place before the connection acquires its names.
Of course, this means developers really should make sure to keep the
settings in .busname units in sync with what they later intend to
negotiate.
safe_close() automatically becomes a NOP when a negative fd is passed,
and returns -1 unconditionally. This makes it easy to write lines like
this:
fd = safe_close(fd);
Which will close an fd if it is open, and reset the fd variable
correctly.
By making use of this new scheme we can drop a > 200 lines of code that
was required to test for non-negative fds or to reset the closed fd
variable afterwards.
After all, it is ultimately linked to libsystems.so anyway, thus belongs
there and shares very little with the rest of logind, hence let's move
this away.
GCC optimizes strlen("string constant") to a constant, even with -O0.
Thus, replace patterns like sizeof("string constant")-1 with
strlen("string constant") where possible, for clarity. In particular,
for expressions intended to add up the lengths of components going into
a string, this often makes it clearer that the expression counts the
trailing '\0' exactly once, by putting the +1 for the '\0' at the end of
the expression, rather than hidden in a sizeof in the middle of the
expression.
This broke hashtable lookups for the message cookies on s390x, which is
a 64bit BE machine where accessing 32bit values as 64bit and vice versa
will explode.
Also, while we are at it, be a bit more careful when dealing with the
64bit cookies we expose and the 32bit serial numbers dbus uses in its
payload.
Problem identified by Fridrich Strba.
Lukasz Skalski
Steven Siloti
Tom Gundersen
Thomas Hindoe Paaboel Andersen
Susant Sahani
Lennart Poettering
Daniel Mack
David Herrmann
Miklos Vajna
Josh Triplett