mirror of
https://gitlab.freedesktop.org/wayland/wayland.git
synced 2026-02-06 04:06:19 -05:00
Core Wayland window system code and protocol
cf4f5995dc
Linux will let you mmap a region of a file that is larger than the size of the file. If you then try to read from that region the process will get a SIGBUS signal. Currently the clients can use this to crash a compositor because it can create a pool and lie about the size of the file which will cause the compositor to try and read past the end of it. The compositor can't simply check the size of the file to verify that it is big enough because then there is a race condition where the client may truncate the file after the check is performed. This patch adds the following two public functions in the server API which can be used wrap access to an SHM buffer: void wl_shm_buffer_begin_access(struct wl_shm_buffer *buffer); void wl_shm_buffer_end_access(struct wl_shm_buffer *buffer); The first time wl_shm_buffer_begin_access is called a signal handler for SIGBUS will be installed. If the signal is caught then the buffer for the current pool is remapped to an anonymous private buffer at the same address which allows the compositor to continue without crashing. The end_access function will then post an error to the buffer resource. The current pool is stored as part of some thread-local storage so that multiple threads can safely independently access separate buffers. Eventually we may want to add some more API so that compositors can hook into the signal handler or replace it entirely if they also want to do some SIGBUS handling. |
||
|---|---|---|
| cursor | ||
| doc | ||
| m4 | ||
| protocol | ||
| spec | ||
| src | ||
| tests | ||
| .gitignore | ||
| autogen.sh | ||
| configure.ac | ||
| COPYING | ||
| Makefile.am | ||
| README | ||
| TODO | ||
| wayland-scanner.m4 | ||
| wayland-scanner.mk | ||
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 git://anongit.freedesktop.org/wayland/wayland
$ cd wayland
$ ./autogen.sh --prefix=PREFIX
$ make
$ make install
where PREFIX is where you want to install the libraries. See
http://wayland.freedesktop.org for more complete build instructions
for wayland, weston, xwayland and various toolkits.