sharedgpures.sys: Request less permissions to duplicate handles

MAINTAINERS

@@ -203,6 +203,7 @@ F:	dlls/jscript/
 Joystick input
 M:	Rémi Bernon <[email protected]>
 F:	dlls/dinput*/
+F:	dlls/gameinput/
 F:	dlls/joy.cpl/
 F:	dlls/windows.gaming.input/
 F:	dlls/winebus.sys/

README.esync

@@ -0,0 +1,196 @@
+This is eventfd-based synchronization, or 'esync' for short. Turn it on with
+WINEESYNC=1; debug it with +esync.
+
+== BUGS AND LIMITATIONS ==
+
+Please let me know if you find any bugs. If you can, also attach a log with
++seh,+pid,+esync,+server,+timestamp.
+
+If you get something like "eventfd: Too many open files" and then things start
+crashing, you've probably run out of file descriptors. esync creates one
+eventfd descriptor for each synchronization object, and some games may use a
+large number of these.  Linux by default limits a process to 4096 file
+descriptors, which probably was reasonable back in the nineties but isn't
+really anymore. (Fortunately Debian and derivatives [Ubuntu, Mint] already
+have a reasonable limit.) To raise the limit you'll want to edit
+/etc/security/limits.conf and add a line like
+
+* hard nofile 1048576
+
+then restart your session.
+
+On distributions using systemd, the settings in `/etc/security/limits.conf`
+will be overridden by systemd's own settings. If you run `ulimit -Hn` and it
+returns a lower number than the one you've previously set, then you can set
+
+DefaultLimitNOFILE=1024:1048576
+
+in both `/etc/systemd/system.conf` and `/etc/systemd/user.conf`. You can then
+execute `sudo systemctl daemon-reexec` and restart your session. Check again
+with `ulimit -Hn` that the limit is correct.
+
+Also note that if the wineserver has esync active, all clients also must, and
+vice versa. Otherwise things will probably crash quite badly.
+
+== EXPLANATION ==
+
+The aim is to execute all synchronization operations in "user-space", that is,
+without going through wineserver. We do this using Linux's eventfd
+facility. The main impetus to using eventfd is so that we can poll multiple
+objects at once; in particular we can't do this with futexes, or pthread
+semaphores, or the like. The only way I know of to wait on any of multiple
+objects is to use select/poll/epoll to wait on multiple fds, and eventfd gives
+us those fds in a quite usable way.
+
+Whenever a semaphore, event, or mutex is created, we have the server, instead
+of creating a traditional server-side event/semaphore/mutex, instead create an
+'esync' primitive. These live in esync.c and are very slim objects; in fact,
+they don't even know what type of primitive they are. The server is involved
+at all because we still need a way of creating named objects, passing handles
+to another process, etc.
+
+The server creates an eventfd file descriptor with the requested parameters
+and passes it back to ntdll. ntdll creates an object of the appropriate type,
+then caches it in a table. This table is copied almost wholesale from the fd
+cache code in server.c.
+
+Specific operations follow quite straightforwardly from eventfd:
+
+* To release an object, or set an event, we simply write() to it.
+* An object is signalled if read() succeeds on it. Notably, we create all
+  eventfd descriptors with O_NONBLOCK, so that we can atomically check if an
+  object is signalled and grab it if it is. This also lets us reset events.
+* For objects whose state should not be reset upon waiting—e.g. manual-reset
+  events—we simply check for the POLLIN flag instead of reading.
+* Semaphores are handled by the EFD_SEMAPHORE flag. This matches up quite well
+  (although with some difficulties; see below).
+* Mutexes store their owner thread locally. This isn't reliable information if
+  a different process's thread owns the mutex, but this doesn't matter—a
+  thread should only care whether it owns the mutex, so it knows whether to
+  try waiting on it or simply to increase the recursion count.
+
+The interesting part about esync is that (almost) all waits happen in ntdll,
+including those on server-bound objects. The idea here is that on the server
+side, for any waitable object, we create an eventfd file descriptor (not an
+esync primitive), and then pass it to ntdll if the program tries to wait on
+it. These are cached too, so only the first wait will require a round trip to
+the server. Then the server signals the file descriptor as appropriate, and
+thereby wakes up the client. So far this is implemented for processes,
+threads, message queues (difficult; see below), and device managers (necessary
+for drivers to work). All of these are necessarily server-bound, so we
+wouldn't really gain anything by signalling on the client side instead. Of
+course, except possibly for message queues, it's not likely that any program
+(cutting-edge D3D game or not) is going to be causing a great wineserver load
+by waiting on any of these objects; the motivation was rather to provide a way
+to wait on ntdll-bound and server-bound objects at the same time.
+
+Some cases are still passed to the server, and there's probably no reason not
+to keep them that way. Those that I noticed while testing include: async
+objects, which are internal to the file APIs and never exposed to userspace,
+startup_info objects, which are internal to the loader and signalled when a
+process starts, and keyed events, which are exposed through an ntdll API
+(although not through kernel32) but can't be mixed with other objects (you
+have to use NtWaitForKeyedEvent()). Other cases include: named pipes, debug
+events, sockets, and timers. It's unlikely we'll want to optimize debug events
+or sockets (or any of the other, rather rare, objects), but it is possible
+we'll want to optimize named pipes or timers.
+
+There were two sort of complications when working out the above. The first one
+was events. The trouble is that (1) the server actually creates some events by
+itself and (2) the server sometimes manipulates events passed by the
+client. Resolving the first case was easy enough, and merely entailed creating
+eventfd descriptors for the events the same way as for processes and threads
+(note that we don't really lose anything this way; the events include
+"LowMemoryCondition" and the event that signals system processes to shut
+down). For the second case I basically had to hook the server-side event
+functions to redirect to esync versions if the event was actually an esync
+primitive.
+
+The second complication was message queues. The difficulty here is that X11
+signals events by writing into a pipe (at least I think it's a pipe?), and so
+as a result wineserver has to poll on that descriptor. In theory we could just
+let wineserver do so and then signal us as appropriate, except that wineserver
+only polls on the pipe when the thread is waiting for events (otherwise we'd
+get e.g. keyboard input while the thread is doing something else, and spin
+forever trying to wake up a thread that doesn't care). The obvious solution is
+just to poll on that fd ourselves, and that's what I did—it's just that
+getting the fd from wineserver was kind of ugly, and the code for waiting was
+also kind of ugly basically because we have to wait on both X11's fd and the
+"normal" process/thread-style wineserver fd that we use to signal sent
+messages. The upshot about the whole thing was that races are basically
+impossible, since a thread can only wait on its own queue.
+
+System APCs already work, since the server will forcibly suspend a thread if
+it's not already waiting, and so we just need to check for EINTR from
+poll(). User APCs and alertable waits are implemented in a similar style to
+message queues (well, sort of): whenever someone executes an alertable wait,
+we add an additional eventfd to the list, which the server signals when an APC
+arrives. If that eventfd gets signaled, we hand it off to the server to take
+care of, and return STATUS_USER_APC.
+
+Originally I kept the volatile state of semaphores and mutexes inside a
+variable local to the handle, with the knowledge that this would break if
+someone tried to open the handle elsewhere or duplicate it. It did, and so now
+this state is stored inside shared memory. This is of the POSIX variety, is
+allocated by the server (but never mapped there) and lives under the path
+"/wine-esync".
+
+There are a couple things that this infrastructure can't handle, although
+surprisingly there aren't that many. In particular:
+* Implementing wait-all, i.e. WaitForMultipleObjects(..., TRUE, ...), is not
+  exactly possible the way we'd like it to be possible. In theory that
+  function should wait until it knows all objects are available, then grab
+  them all at once atomically. The server (like the kernel) can do this
+  because the server is single-threaded and can't race with itself. We can't
+  do this in ntdll, though. The approach I've taken I've laid out in great
+  detail in the relevant patch, but for a quick summary we poll on each object
+  until it's signaled (but don't grab it), check them all again, and if
+  they're all signaled we try to grab them all at once in a tight loop, and if
+  we fail on any of them we reset the count on whatever we shouldn't have
+  consumed. Such a blip would necessarily be very quick.
+* The whole patchset only works on Linux, where eventfd is available. However,
+  it should be possible to make it work on a Mac, since eventfd is just a
+  quicker, easier way to use pipes (i.e. instead of writing 1 to the fd you'd
+  write 1 byte; instead of reading a 64-bit value from the fd you'd read as
+  many bytes as you can carry, which is admittedly less than 2**64 but
+  can probably be something reasonable.) It's also possible, although I
+  haven't yet looked, to use some different kind of synchronization
+  primitives, but pipes would be easiest to tack onto this framework.
+* PulseEvent() can't work the way it's supposed to work. Fortunately it's rare
+  and deprecated. It's also explicitly mentioned on MSDN that a thread can
+  miss the notification for a kernel APC, so in a sense we're not necessarily
+  doing anything wrong.
+
+There are some things that are perfectly implementable but that I just haven't
+done yet:
+* Other synchronizable server primitives. It's unlikely we'll need any of
+  these, except perhaps named pipes (which would honestly be rather difficult)
+  and (maybe) timers.
+* Access masks. We'd need to store these inside ntdll, and validate them when
+  someone tries to execute esync operations.
+
+This patchset was inspired by Daniel Santos' "hybrid synchronization"
+patchset. My idea was to create a framework whereby even contended waits could
+be executed in userspace, eliminating a lot of the complexity that his
+synchronization primitives used. I do however owe some significant gratitude
+toward him for setting me on the right path.
+
+I've tried to maximize code separation, both to make any potential rebases
+easier and to ensure that esync is only active when configured. All code in
+existing source files is guarded with "if (do_esync())", and generally that
+condition is followed by "return esync_version_of_this_method(...);", where
+the latter lives in esync.c and is declared in esync.h. I've also tried to
+make the patchset very clear and readable—to write it as if I were going to
+submit it upstream. (Some intermediate patches do break things, which Wine is
+generally against, but I think it's for the better in this case.) I have cut
+some corners, though; there is some error checking missing, or implicit
+assumptions that the program is behaving correctly.
+
+I've tried to be careful about races. There are a lot of comments whose
+purpose are basically to assure me that races are impossible. In most cases we
+don't have to worry about races since all of the low-level synchronization is
+done by the kernel.
+
+Anyway, yeah, this is esync. Use it if you like.
+
+--Zebediah Figura

autogen.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+set -e
+tools/make_requests
+tools/make_specfiles
+dlls/winevulkan/make_vulkan -x vk.xml -X video.xml
+autoreconf -ifv
+rm -rf autom4te.cache
+
+echo "Now run ./configure"