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Core Wayland window system code and protocol
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Duncan McIntosh 20fd3b3af9 wayland-shm: Check the size of sealed memory if ignoring SIGBUS handlers 
In 11623e8f, SIGBUS handlers aren't set if F_SEAL_SHRINK is configured on
the memory. This helps avoid setting up handlers with cooperative clients;
however, if an application gives an incorrect size, the compositor would
access it anyways, figuring SIGBUS is impossible, and crash.

This can be fixed by simply removing the seal-checking logic and always
setting the signal handler. However, it seems that fstat can give the size
of the memfd, so we can check that the size we were told is within the
region. Since it's sealed to shrinking, it must never be shrunk in future,
so we can really (hopefully) ignore SIGBUS.

I was worried that fstat wasn't supported for this, but shm_overview(7) does
mention that it is a possible use.

The best solution would likely be avoiding SIGBUS entirely with
MAP_NOSIGBUS, but that hasn't been merged yet and wouldn't help systems
without it (e.g. with older kernels).

A proof-of-concept of this crash is attached with the merge request. Running
it with this patch gives an invalid-shm error, which is correct.

Signed-off-by: Duncan McIntosh <duncan82013@live.ca>
2021-11-04 09:02:19 +00:00
.gitlab/issue_templates Add a basic gitlab issue template 2020-08-18 07:57:26 +00:00
cursor build: Include the Wayland minor version in libraries' ABI versions 2021-10-28 12:46:06 +00:00
doc build: drop autotools 2021-03-05 09:15:04 +00:00
egl build: Include the Wayland minor version in libraries' ABI versions 2021-10-28 12:46:06 +00:00
protocol protocol: wl_shm uses pre-multiplied alpha 2021-11-04 08:53:47 +00:00
src wayland-shm: Check the size of sealed memory if ignoring SIGBUS handlers 2021-11-04 09:02:19 +00:00
tests server: stop wl_display event loop from any context 2021-10-09 13:09:04 +00:00
.editorconfig editorconfig: add settings for the .gitlab-ci.yml file 2020-06-05 08:22:34 +10:00
.gitignore build: drop autotools 2021-03-05 09:15:04 +00:00
.gitlab-ci.yml gitlab-ci: add a FreeBSD test job 2021-09-10 11:35:54 +00:00
CONTRIBUTING.md CONTRIBUTING: fix typo "excercising" 2020-12-17 16:03:14 -05:00
COPYING COPYING: Update to MIT Expat License rather than MIT X License 2015-06-12 15:31:21 -07:00
meson.build build: Include the Wayland minor version in libraries' ABI versions 2021-10-28 12:46:06 +00:00
meson_options.txt build: add option to disable tests 2021-04-16 03:45:06 -06:00
publish-doc publish-doc: Add script for publishing docs to the website 2015-05-27 15:34:20 -07:00
README README with upadated compile instructions 2020-04-07 10:55:19 -07:00
releasing.txt build: drop autotools 2021-03-05 09:15:04 +00:00
wayland-scanner.m4 build: check wayland-scanner version 2020-01-16 17:25:06 +01:00
wayland-scanner.mk Pass input/output files as arguments to wayland-scanner 2017-08-18 15:20:24 +03:00

README 

What is Wayland?

Wayland is a project to define a protocol for a compositor to talk to
its clients as well as a library implementation of the protocol.  The
compositor can be a standalone display server running on Linux kernel
modesetting and evdev input devices, an X application, or a wayland
client itself.  The clients can be traditional applications, X servers
(rootless or fullscreen) or other display servers.

The wayland protocol is essentially only about input handling and
buffer management.  The compositor receives input events and forwards
them to the relevant client.  The clients creates buffers and renders
into them and notifies the compositor when it needs to redraw.  The
protocol also handles drag and drop, selections, window management and
other interactions that must go through the compositor.  However, the
protocol does not handle rendering, which is one of the features that
makes wayland so simple.  All clients are expected to handle rendering
themselves, typically through cairo or OpenGL.

The weston compositor is a reference implementation of a wayland
compositor and the weston repository also includes a few example
clients.

Building the wayland libraries is fairly simple, aside from libffi,
they don't have many dependencies:

    $ git clone https://gitlab.freedesktop.org/wayland/wayland
    $ cd wayland
    $ meson build/ --prefix=PREFIX
    $ ninja -C build/ install

where PREFIX is where you want to install the libraries.  See
https://wayland.freedesktop.org for more complete build instructions
for wayland, weston, xwayland and various toolkits.