Libraries like Xlib, some XCB language bindings, and potentially others
have a common problem: they want to share the X connection with XCB. This
requires coordination of request sequence numbers. Previously, XCB had an
Xlib-specific lock, and allowed Xlib to block XCB from making requests.
Now we've replaced that lock with a handoff mechanism, xcb_take_socket,
allowing external code to ask XCB for permission to take over the write
side of the socket and send raw data with xcb_writev. The caller of
xcb_take_socket must supply a callback which XCB can call when it wants
the write side of the socket back to make a request. This callback
synchronizes with the external socket owner, flushes any output queues if
appropriate, and then returns the sequence number of the last request sent
over the socket.
Commit by Josh Triplett and Jamey Sharp.
Handoff mechanism inspired by Keith Packard.
This allows optimizing adjacent pending replies with the same flags, and
will help support default flags for a range of future requests.
Commit by Josh Triplett and Jamey Sharp.
The GNU/kFreeBSD (and BSDs in general) have a different
layout of struct sockaddr, sockaddr_in, sockaddr_un ...
The first member do not have to be "sa_family",
they also have "sa_len" field.
Signed-off-by: Julien Danjou <julien@danjou.info>
GenericEvent can be more than 32 bytes long. Ensure that the required data is
pulled off the wire and tack it onto the event.
Due to the structure of the xcb_generic_event_t, the data is appended AFTER
the full_sequence field.
Since several extensions named their errors like "BadFoo", this patch
results in names like XCB_EXT_BAD_BAD_FOO, which is really awful. Those
extensions are already kind of awful, as they produce structure names
like xcb_ext_bad_foo_error_t, which is redundant.
A patch that removes "Bad" from the XML extension descriptions, while
maintaining API and ABI compatibility in XCB, is needed before this
patch can be released.
This reverts commit 158c9b6ba1.
With this patch, `ico -threads 2` runs without deadlock.
Many thanks to Christoph Pfister <christophpfister@gmail.com> for
pointing out the problem, providing detailed analyses, explaining it to
me repeatedly until I understood what was going on, and proposing and
reviewing possible solutions.
Signed-off-by: Jamey Sharp <jamey@minilop.net>
Acked-by: Christoph Pfister <christophpfister@gmail.com>
But do still print a full backtrace, on platforms where that's
supported.
This commit follows the spirit of Novell's libxcb-sloppy-lock.diff.
I strongly opposed proposals like this one for a long time. Originally I
had a very good reason: libX11, when compiled to use XCB, would crash
soon after a locking correctness violation, so it was better to have an
informative assert failure than a mystifying crash soon after.
It took some time for me to realize that I'd changed the libX11
implementation (for unrelated reasons) so that it could survive most
invalid locking situations, as long as it wasn't actually being used
from multiple threads concurrently.
The other thing that has changed is that most of the code with incorrect
locking has now been fixed. The value of the assert is accordingly
lower.
However, remaining broken callers do need to be fixed. That's why libXCB
will still noisily print a stacktrace (if possible) on each assertion
failure, even when assert isn't actually invoked to abort() the program;
and that's why aborting is still default. This environment variable is
provided only for use as a temporary workaround for broken applications.
Signed-off-by: Jamey Sharp <jamey@minilop.net>
Acked-by: Josh Triplett <josh@freedesktop.org>
As you know there are some nasty libs / apps doing locking
incorrectly. In order to improve the information given to the user
when he encounters such a situation (people don't run apps in gdb
normally) I created the patch attached.
It's very non-intrusive (and affects only xlib/xcb, Josh told me on
irc that it could be useful for other areas too, personally I don't
think that it's really needed at other places ...).
Some same outputs and the discussion of them:
lxuser@pdln:/tmp$ ./main
Got a backtrace:
#0 /tmp/usr/lib/libxcb-xlib.so.0 [0xb7f9d728]
#1 /tmp/usr/lib/libxcb-xlib.so.0(xcb_xlib_unlock+0x31) [0xb7f9d861]
#2 ./test.so(function_a+0x11) [0xb7f9f3fd]
#3 ./test.so(function_b+0x11) [0xb7f9f410]
#4 ./main [0x80484a7]
#5 /lib/libc.so.6(__libc_start_main+0xdc) [0xb7e60ebc]
#6 ./main [0x80483f1]
main: xcb_xlib.c:82: xcb_xlib_unlock: Assertion `c->xlib.lock' failed.
Aborted
That's kinda the normal situation.
lxuser@pdln:/tmp$ ./main
Got a backtrace:
#0 /tmp/usr/lib/libxcb-xlib.so.0 [0xb7f90728]
#1 /tmp/usr/lib/libxcb-xlib.so.0(xcb_xlib_unlock+0x31) [0xb7f90861]
#2 /tmp/test.so [0xb7f923cd]
#3 /tmp/test.so(function_b+0x11) [0xb7f923e0]
#4 ./main [0x80484ab]
#5 /lib/libc.so.6(__libc_start_main+0xdc) [0xb7e53ebc]
#6 ./main [0x80483f1]
main: xcb_xlib.c:82: xcb_xlib_unlock: Assertion `c->xlib.lock' failed.
Aborted
There are two possible reasons that the name doesn't appear in #2:
a) a hidden symbol or a symbol with statical linkage in a library
b) a symbol in an app not compiled with -rdynamic.
But in both cases you still know _where_ the caller is.
Note that in this example test.so was compiled with
-fomit-frame-pointer; this isn't an issue as _one_ (= the caller)
stack trace is still valid (as long as you don't have the insane idea
to compile xcb with -fo-f-p).
Another issue that may appear is "tail call elimination" (some entries
are mysteriously missing; this is quite ugly, but you still get enough
information so that you can do something useful with the issue e.g. by
disassembling the relevant parts with gdb).
Signed-off-by: Jamey Sharp <jamey@minilop.net>
Avoid race condition when symlinking XML files.
When declaring a rule with many files as target, the rule is called
when any of them is requested, resulting in multiple for loops happening
during a make process using more than one job.
Also, use '$(LN_S) -f' rather than removing and recreating a file,
that one should be as supported as 'rm -f' and requires one less command.
Josh Triplett
Jamey Sharp
Henning Sten
Carsten Meier
Julien Cristau
Bart Massey
Vincent Torri
Julien Danjou
Petr Salinger
Peter Hutterer
Oswald Buddenhagen
Eamon Walsh
Jeremy Kolb
Egbert Eich
Christoph Pfister
Ian Osgood
TORRI Vincent
TORRI Vincent
Diego 'Flameeyes' Pettenò