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84 lines
2.8 KiB
84 lines
2.8 KiB
# DBUS Role Support
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## DBUS-related distro packages
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Fedora: dbus-devel
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Debian / Ubuntu: libdbus-1-dev
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## Enabling for build at cmake
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Fedora example:
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```
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$ cmake .. -DLWS_ROLE_DBUS=1 -DLWS_DBUS_INCLUDE2="/usr/lib64/dbus-1.0/include"
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```
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Ubuntu example:
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```
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$ cmake .. -DLWS_ROLE_DBUS=1 -DLWS_DBUS_INCLUDE2="/usr/lib/x86_64-linux-gnu/dbus-1.0/include"
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```
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Dbus requires two include paths, which you can force by setting `LWS_DBUS_INCLUDE1`
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and `LWS_DBUS_INCLUDE2`. Although INCLUDE1 is usually guessable, both can be
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forced to allow cross-build.
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If these are not forced, then lws cmake will try to check some popular places,
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for `LWS_DBUS_INCLUDE1`, on both Fedora and Debian / Ubuntu, this is
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`/usr/include/dbus-1.0`... if the directory exists, it is used.
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For `LWS_DBUS_INCLUDE2`, it is the arch-specific dbus header which may be
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packaged separately than the main dbus headers. On Fedora, this is in
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`/usr/lib[64]/dbus-1.0/include`... if not given externally, lws cmake will
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try `/usr/lib64/dbus-1.0/include`. On Debian / Ubuntu, the package installs
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it in an arch-specific dir like `/usr/lib/x86_64-linux-gnu/dbus-1.0/include`,
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you should force the path.
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The library path is usually \[lib\] "dbus-1", but this can also be forced if
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you want to build cross or use a special build, via `LWS_DBUS_LIB`.
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## Building against local dbus build
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If you built your own local dbus and installed it in /usr/local, then
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this is the incantation to direct lws to use the local version of dbus:
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```
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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"
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```
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You'll also need to give the loader a helping hand to do what you want if
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there's a perfectly good dbus lib already in `/usr/lib[64]` using `LD_PRELOAD`
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like this
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```
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LD_PRELOAD=/usr/local/lib/libdbus-1.so.3.24.0 myapp
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```
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## Lws dbus api exports
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Because of the irregular situation with libdbus includes, if lws exports the
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dbus helpers, which use dbus types, as usual from `#include <libwebsockets.h>`
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then if lws was compiled with dbus role support it forces all users to take
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care about the dbus include path mess whether they use dbus themselves or not.
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For that reason, if you need access to the lws dbus apis, you must explicitly
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include them by
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```
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#include <libwebsockets/lws-dbus.h>
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```
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This includes `<dbus/dbus.h>` and so requires the include paths set up. But
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otherwise non-dbus users that don't include `libwebsockets/lws-dbus.h` don't
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have to care about it.
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## DBUS and valgrind
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https://cgit.freedesktop.org/dbus/dbus/tree/README.valgrind
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1) One-time 6KiB "Still reachable" caused by abstract unix domain socket + libc
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`getgrouplist()` via nss... bug since 2004(!)
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https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=273051
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