mirror of
https://libwebsockets.org/repo/libwebsockets
synced 2024-11-24 01:39:33 +00:00
31dfc4aa12
This adds support for the integrating libdbus into the lws event loop. Unlike the other roles, lws doesn't completely adopt the fd and libdbus insists to retain control over the fd lifecycle. However libdbus provides apis for foreign code (lws) to provide event loop services to libdbus for the fd. Accordingly, unlike the other roles rx and writeable are not subsumed into lws callback messages and the events remain the property of libdbus. A context struct wrapper is provided that is available in the libdbus callbacks to bridge between the lws and dbus worlds, along with a minimal example dbus client and server.
84 lines
2.8 KiB
Markdown
84 lines
2.8 KiB
Markdown
# DBUS Role Support
|
|
|
|
## DBUS-related distro packages
|
|
|
|
Fedora: dbus-devel
|
|
Debian / Ubuntu: libdbus-1-dev
|
|
|
|
## Enabling for build at cmake
|
|
|
|
Fedora example:
|
|
```
|
|
$ cmake .. -DLWS_ROLE_DBUS=1 -DLWS_DBUS_INCLUDE2="/usr/lib64/dbus-1.0/include"
|
|
```
|
|
|
|
Ubuntu example:
|
|
```
|
|
$ cmake .. -DLWS_ROLE_DBUS=1 -DLWS_DBUS_INCLUDE2="/usr/lib/x86_64-linux-gnu/dbus-1.0/include"
|
|
```
|
|
|
|
Dbus requires two include paths, which you can force by setting `LWS_DBUS_INCLUDE1`
|
|
and `LWS_DBUS_INCLUDE2`. Although INCLUDE1 is usually guessable, both can be
|
|
forced to allow cross-build.
|
|
|
|
If these are not forced, then lws cmake will try to check some popular places,
|
|
for `LWS_DBUS_INCLUDE1`, on both Fedora and Debian / Ubuntu, this is
|
|
`/usr/include/dbus-1.0`... if the directory exists, it is used.
|
|
|
|
For `LWS_DBUS_INCLUDE2`, it is the arch-specific dbus header which may be
|
|
packaged separately than the main dbus headers. On Fedora, this is in
|
|
`/usr/lib[64]/dbus-1.0/include`... if not given externally, lws cmake will
|
|
try `/usr/lib64/dbus-1.0/include`. On Debian / Ubuntu, the package installs
|
|
it in an arch-specific dir like `/usr/lib/x86_64-linux-gnu/dbus-1.0/include`,
|
|
you should force the path.
|
|
|
|
The library path is usually \[lib\] "dbus-1", but this can also be forced if
|
|
you want to build cross or use a special build, via `LWS_DBUS_LIB`.
|
|
|
|
## Building against local dbus build
|
|
|
|
If you built your own local dbus and installed it in /usr/local, then
|
|
this is the incantation to direct lws to use the local version of dbus:
|
|
|
|
```
|
|
cmake .. -DLWS_ROLE_DBUS=1 -DLWS_DBUS_INCLUDE1="/usr/local/include/dbus-1.0" -DLWS_DBUS_INCLUDE2="/usr/local/lib/dbus-1.0/include" -DLWS_DBUS_LIB="/usr/local/lib/libdbus-1.so"
|
|
```
|
|
|
|
You'll also need to give the loader a helping hand to do what you want if
|
|
there's a perfectly good dbus lib already in `/usr/lib[64]` using `LD_PRELOAD`
|
|
like this
|
|
|
|
```
|
|
LD_PRELOAD=/usr/local/lib/libdbus-1.so.3.24.0 myapp
|
|
```
|
|
|
|
## Lws dbus api exports
|
|
|
|
Because of the irregular situation with libdbus includes, if lws exports the
|
|
dbus helpers, which use dbus types, as usual from `#include <libwebsockets.h>`
|
|
then if lws was compiled with dbus role support it forces all users to take
|
|
care about the dbus include path mess whether they use dbus themselves or not.
|
|
|
|
For that reason, if you need access to the lws dbus apis, you must explicitly
|
|
include them by
|
|
|
|
```
|
|
#include <libwebsockets/lws-dbus.h>
|
|
```
|
|
|
|
This includes `<dbus/dbus.h>` and so requires the include paths set up. But
|
|
otherwise non-dbus users that don't include `libwebsockets/lws-dbus.h` don't
|
|
have to care about it.
|
|
|
|
## DBUS and valgrind
|
|
|
|
https://cgit.freedesktop.org/dbus/dbus/tree/README.valgrind
|
|
|
|
1) One-time 6KiB "Still reachable" caused by abstract unix domain socket + libc
|
|
`getgrouplist()` via nss... bug since 2004(!)
|
|
|
|
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=273051
|
|
|
|
|
|
|