IPC: use RMIB to handle kern.ipc sysctl subtree

With this patch, the IPC service is changed to use the new RMIB
facility to register and handle the "kern.ipc" sysctl subtree itself.
The subtree was

IPC: use RMIB to handle kern.ipc sysctl subtree

With this patch, the IPC service is changed to use the new RMIB
facility to register and handle the "kern.ipc" sysctl subtree itself.
The subtree was previously handled by the MIB service directly. This
change improves locality of handling: especially the
kern.ipc.sysvipc_info node has some peculiarities specific to the IPC
service and is therefore better handled there. Also, since the IPC
service is essentially optional to the system, this rearrangement
yields a cleaner situation when the IPC service is not running: in
that case, the MIB service will expose a few basic kern.ipc nodes
indicating that no SysV IPC facilities are present. Those nodes will
be overridden through RMIB when the IPC service is running.

It should be easier to add the remaining (from NetBSD) kern.ipc nodes
as well now.

Test88 is extended with a new subtest that verifies that sysctl-based
information retrieval for semaphore sets works as expected.

Change-Id: I6b7730e85305b64cfd8418c0cc56bde64b22c584

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IPC server: subscribe to process events on demand

As mentioned in previous patches, services may not subscribe to
process events from specific processes only, since this results in
race conditions.

IPC server: subscribe to process events on demand

As mentioned in previous patches, services may not subscribe to
process events from specific processes only, since this results in
race conditions. However, the IPC server can safely turn on and off
its entire subscription based on whether any System V IPC semaphores
(and, in the future, message queues) are allocated at all. Since
the System V IPC facilities are not so commonly used, this removes
the extra round trip from PM to the IPC server and back for caught
signals and process exits in the common case.

Change-Id: I937259034872be32f4e26ab99270f4d475ff6134

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IPC server: major fixes, test set for semaphores

- rewrite the semop(2) implementation so that it now conforms to the
specification, including atomicity, support for blocking more than
once, ran

IPC server: major fixes, test set for semaphores

- rewrite the semop(2) implementation so that it now conforms to the
specification, including atomicity, support for blocking more than
once, range checks, but also basic fairness support;
- fix permissions checking;
- fix missing time adjustments;
- fix off-by-one errors and other bugs;
- do not allocate dynamic memory for GETALL/SETALL;
- add test88, which properly tests the semaphore functionality.

Change-Id: I85f0d3408c0d6bba41cfb4c91a34c8b46b2a5959

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PM: generic process event publish/subscribe system

Now that there are services other than PM and VFS that implement
userland system calls directly, these services may need to know about
events relat

PM: generic process event publish/subscribe system

Now that there are services other than PM and VFS that implement
userland system calls directly, these services may need to know about
events related to user processes. In particular, signal delivery may
have to interrupt blocking system calls, and certain cleanup tasks may
have to be performed after a user process exits.

This patch aims to implement a generic, lasting solution for this
problem, by allowing services to subscribe to "signal delivered"
and/or "process exit" events from PM. PM publishes such events by
sending messages to its subscribed services, which must then reply an
acknowledgment message.

For now, only the two aforementioned events are implemented, and only
the IPC service makes use of the process event facility.

The new process event publish/subscribe system replaces the previous
VM notify-sig/watch-exit/query-exit system, which was unsound: 1) it
allowed subscription to events from individual processes, and suffered
from fundamental race conditions as a result; 2) it relied on "not too
many" processes making use of the IPC server functionality in order to
avoid loss of notifications. In addition, it had the "ipc" process
name hardcoded, did not distinguish between signal delivery and exits,
and added a roundtrip to VM for all events from all processes.

Change-Id: I75ebad4bc54e646c6433f473294cb4003b2c3430

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IPC server: restyle

Closer to KNF, better coding practices, more similar to other
services, no more global variables, a few more comments, that
kind of stuff. No major functional changes.

Change-I

IPC server: restyle

Closer to KNF, better coding practices, more similar to other
services, no more global variables, a few more comments, that
kind of stuff. No major functional changes.

Change-Id: I6e8f53bfafd6f41e92031fba76c40a31d2107a8e

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IPC server: NetBSD sync, general improvements

- switch to the NetBSD identifier system; it is not only better, but
also required for porting NetBSD ipcs(1) and ipcrm(1); however, it
requires tha

IPC server: NetBSD sync, general improvements

- switch to the NetBSD identifier system; it is not only better, but
also required for porting NetBSD ipcs(1) and ipcrm(1); however, it
requires that slots not be moved, and that results in some changes;
- synchronize some other things with NetBSD: where keys are kept, as
well as various non-permission mode flags;
- fix semctl(2) vararg retrieval and message field type;
- use SUSPEND instead of weird reply exceptions in the call table;
- fix several memory leaks and at least one missing permission check;
- improve the atomicity of semop(2) by a small amount, even though
its atomicity is still broken at a fundamental level;
- use the new cheaper way to retrieve the current time;
- resolve all level-5 LLVM warnings.

Change-Id: I0c47aacde478b23bb77d628384aeab855a22fdbf

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IPC server: expose semaphore information

Specifically, add support for the IPC_INFO, SEM_INFO, and SEM_STAT
semctl(2) operations, similar to how information about shared memory
is already exposed as

IPC server: expose semaphore information

Specifically, add support for the IPC_INFO, SEM_INFO, and SEM_STAT
semctl(2) operations, similar to how information about shared memory
is already exposed as well. The MINIX3 ipcs(1) utility already had
support for these operations, and can now actually use them, too.

Change-Id: Ice5a02e729bf6df6aa8fab76e854808adc04dae3

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New sources layout

Change-Id: Ic716f336b7071063997cf5b4dae6d50e0b4631e9