While XCB uses 64-bit sequence number internally, it only exposes
"unsigned int" so that, on 32-bit architecture, Xlib based applications
may see their sequence number wrap which causes the connection to the X
server to be lost.
Expose 64-bit sequence number from XCB API so that Xlib and others can
use it even on 32-bit environment.
This implies the following API addition:
xcb_send_request64()
xcb_discard_reply64()
xcb_wait_for_reply64()
xcb_poll_for_reply64()
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71338
Reviewed-by: Uli Schlachter <psychon@znc.in>
Signed-off-by: Christian Linhart <chris@demorecorder.com>
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
send_request may only write to out.queue if no other thread is busy
writing to the network (as that thread may be writing from out.queue).
send_request may only allocate request sequence numbers if XCB owns
the socket.
Therefore, send_request must make sure that both conditions are true
when it holds iolock, which can only be done by looping until both
conditions are true without having dropped the lock waiting for the
second condition.
We choose to get the socket back from Xlib first as get_socket_back
has a complicated test and checking for other threads writing is a
simple in-lined check.
This also changes the sequence number checks (64k requests with no
reply, 4M request wrapping) to ensure that both conditions are true
before queueing the request.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Uli Schlachter <psychon@znc.in>
This reverts commit 9ae84ad187.
After this patch was merged, there were complaints about it not being a good
idea. Revert this for now until we can agree on this.
References: http://lists.freedesktop.org/archives/xcb/2013-June/008340.html
Signed-off-by: Uli Schlachter <psychon@znc.in>
Conflicts:
src/xcbint.h
This uses sendmsg to transmit file descriptors from the application to
the X server
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-By: Uli Schlachter <psychon@znc.in>
To prevent different threads from stealing the socket from each other the
caller of "xcb_take_socket" must hold a lock that is also acquired in
"return_socket". Unfortunately xcb tries to prevent calling return_socket
from multiple threads and this can lead to a deadlock situation.
A simple example:
- X11 has taken the socket
- Thread A has locked the display.
- Thread B does xcb_no_operation() and thus ends up in libX11's return_socket(),
waiting for the display lock.
- Thread A calls e.g. xcb_no_operation(), too, ends up in return_socket() and
because socket_moving == 1, ends up waiting for thread B
=> Deadlock
This patch allows calling return_socket from different threads at the same time
an so resolves the deadlock situation.
Partially fixes: https://bugs.freedesktop.org/show_bug.cgi?id=20708
v2: fixes additional pthread_cond_wait dependencies,
rework comments and patch description
v3: separate pthread_cond_wait dependencies and unrelated whitespace
change into their own patch, use unsigned for socket_seq
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Uli Schlachter <psychon@znc.in>
Allows configure to set defines such as _POSIX_SOURCE in config.h
that affect functions exposed by system headers and get consistent
results across all the source files.
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=41443
Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=42304
I have added more xcb connection error states at xcb.h header.
Also I have removed global error_connection variable, and added
an interface that returns connection error state.
TBD:
I will segregate errors states in a separate header file and try to
provide more precise error states, in future. Also I will give patch
for libX11, in that patch xcb_connection_t::has_error will be passed
to default io handler of libX11. This value can then be used for
displaying error messages.
Reviewed-by: Rami Ylimäki <rami.ylimaki@vincit.fi>
Reviewed-by: Uli Schlachter <psychon@znc.in>
Signed-off-by: Arvind Umrao <arvind.umrao@oracle.com>
_xcb_out_flush_to will drop the iolock in pthread_cond_wait allowing
other threads to queue new requests. When this happened,
there would be requests queued for the socket after _xcb_out_flush_to
returned, and xcb_take_socket would throw an assert.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29875
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Julien Danjou <julien@danjou.info>
This simplifies the critical section of xcb_send_request and fixes a
couple of subtle bugs:
- It's possible for xcb_send_request to need to issue two sync requests
before it can issue the real request. Previously, we counted sequence
numbers as if both were issued, but only one went out on the wire.
- The test for whether to sync at 32-bit sequence number wrap has been
incorrect since we switched to 64-bit sequence numbers internally.
This change means that if the output queue was already full and the
current request is bigger than the output queue, XCB will do one more
write syscall than it did before. But syncs are rare and small requests
are the norm, so this shouldn't be a measurable difference.
Signed-off-by: Jamey Sharp <jamey@minilop.net>
Since writers must make sure they read as well, threads may have gone to
sleep waiting for the opportunity to read. The writer must wake up one
of those readers or the application can hang.
Signed-off-by: Jamey Sharp <jamey@minilop.net>
Reviewed-by: Josh Triplett <josh@freedesktop.org>
_xcb_out_send needs _xcb_conn_wait to store back its progress so it can
be reinvoked to pick up where it left off---but then _xcb_out_send
guarantees that it leaves either an empty output vector or a shut-down
connection, so *its* callers never care how much progress was made.
Signed-off-by: Jamey Sharp <jamey@minilop.net>
Reviewed-by: Josh Triplett <josh@freedesktop.org>
Also replace excessively clever use of bitwise OR with equivalent
addition.
Reported-by: Geoffrey Li <geoffrey@seitopos.com>
Signed-off-by: Jamey Sharp <jamey@minilop.net>
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
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.
Rename API to follow a new naming convention:
* XCB_CONSTANTS_UPPERCASE_WITH_UNDERSCORES
* xcb_functions_lowercase_with_underscores
* xcb_types_lowercase_with_underscores_and_suffix_t
* expand all abbreviations like "req", "rep", and "iter"
Word boundaries for the names in the protocol descriptions fall:
* Wherever the protocol descriptions already have an underscore
* Between a lowercase letter and a subsequent uppercase letter
* Before the last uppercase letter in a string of uppercase letters followed
by a lowercase letter (such as in LSBFirst between LSB and First)
* Before and after a string of digits (with exceptions for sized types like
xcb_char2b_t and xcb_glx_float32_t to match the stdint.h convention)
Also fix up some particular naming issues:
* Rename shape_op and shape_kind to drop the "shape_" prefix, since otherwise
these types end up as xcb_shape_shape_{op,kind}_t.
* Remove leading underscores from enums in the GLX protocol description,
previously needed to ensure a word separator, but now redundant.
This renaming breaks code written for the previous API naming convention. The
scripts in XCB's tools directory will convert code written for the old API to
use the new API; they work well enough that we used them to convert the
non-program-generated code in XCB, and when run on the old program-generated
code, they almost exactly reproduce the new program-generated code (modulo
whitespace and bugs in the old code generator).
Authors: Vincent Torri, Thomas Hunger, Josh Triplett
Create a macro, XCB_SEQUENCE_COMPARE, that accepts two sequence numbers and
a comparison operator and correctly handles 32-bit wrap around.
Rewrite all ordered sequence number comparisons to use this macro.
Also, caught one error where a sequence was stored in a signed int variable.
Push out a GetInputFocus request when the sequence number does wrap at 32
bits so that applications cannot see sequence 0 (as that is an error
indicator).
Christian Linhart
Keith Packard
Uli Schlachter
Christian König
Alan Coopersmith
Arvind Umrao
Jamey Sharp
Josh Triplett
Julien Danjou
Keith Packard