FEAT(client): Plugin framework

This commit introduces a new plugin framework into the codebase of the
Mumble client. Note that "plugin" here really refers to a (more or less)
general purpose plugin and is therefore not to be confused with the
previously available positional data plugins (only responsible for
fetching positional data from a running game and passing that to
Mumble).

The plugin interface is written in C, removing the compiler-dependence
the old "plugins" had. Instead plugins can now be written in an
arbitrary language as long as that language is capable of being compiled
into a shared library and also being capable of being C-compatible.

As already indicated a plugin is essentially a shared library that
provides certain functions that allow Mumble to interface with it.

Inside Mumble the so-called PluginManager is responsible for managing
the plugins and relaying events to the respective callbacks. Plugins
themselves can also interact with Mumble on their own initiative by
using the provided API functions.

Fixes #2455
Fixes #2148
Fixes #1594
Fixes #2051
Fixes #3742
Fixes #4575
Fixes #4751

.ci/azure-pipelines/install-environment_linux.bash

@@ -14,4 +14,5 @@ sudo apt-get -y install build-essential g++-multilib ninja-build pkg-config \
                         libasound2-dev libasound2-plugins libasound2-plugins-extra\
                         libogg-dev libsndfile1-dev libspeechd-dev \
                         libavahi-compat-libdnssd-dev libzeroc-ice-dev \
-                        zsync appstream libgrpc++-dev protobuf-compiler-grpc
+                        zsync appstream libgrpc++-dev protobuf-compiler-grpc \
+                        libpoco-dev

.cirrus.yml

@@ -8,7 +8,7 @@ freebsd_instance:
 freebsd_task:
   pkg_script:
   - pkg update && pkg upgrade -y
-  - pkg install -y git ninja pkgconf cmake qt5-buildtools qt5-qmake qt5-linguisttools qt5-concurrent qt5-network qt5-xml qt5-sql qt5-svg qt5-testlib boost-libs libsndfile protobuf ice avahi-libdns grpc
+  - pkg install -y git ninja pkgconf cmake qt5-buildtools qt5-qmake qt5-linguisttools qt5-concurrent qt5-network qt5-xml qt5-sql qt5-svg qt5-testlib boost-libs libsndfile protobuf ice avahi-libdns grpc poco
   fetch_submodules_script: git submodule --quiet update --init --recursive
   build_script:
   - mkdir build && cd build

.github/actions/install-dependencies/install_ubuntu_shared_64bit.sh

@@ -29,4 +29,5 @@ sudo apt -y install \
 	zsync \
 	appstream \
 	libgrpc++-dev \
-	protobuf-compiler-grpc
+	protobuf-compiler-grpc \
+	libpoco-dev

CMakeLists.txt

@@ -30,6 +30,7 @@ project(Mumble
 )
 
 set(3RDPARTY_DIR "${CMAKE_SOURCE_DIR}/3rdparty")
+set(PLUGINS_DIR "${CMAKE_SOURCE_DIR}/plugins")
 
 set(CMAKE_CXX_STANDARD 14)
 set(CMAKE_OSX_DEPLOYMENT_TARGET 10.9)

docs/dev/build-instructions/cmake_options.md

@@ -149,6 +149,16 @@ Build 32 bit overlay library, necessary for the overlay to work with 32 bit proc
 Build package.
 (Default: OFF)
 
+### plugin-callback-debug
+
+Build Mumble with debug output for plugin callbacks inside of Mumble.
+(Default: OFF)
+
+### plugin-debug
+
+Build Mumble with debug output for plugin developers.
+(Default: OFF)
+
 ### plugins
 
 Build plugins.

plugins/CMakeLists.txt

@@ -30,6 +30,11 @@ foreach(ITEM ${ITEMS})
 		# PLUGIN_RETRACTED variable in the parent scope so that we can access it here
 		add_subdirectory(${ITEM})
 
+		if(${ITEM} STREQUAL "testPlugin" AND NOT ${CMAKE_BUILD_TYPE} MATCHES Debug)
+			# The testPlugin is only included in Debug builds
+			continue()
+		endif()
+
 		if(PLUGIN_RETRACTED AND NOT retracted-plugins)
 			# The included subdir didn't actually add a target since the associated plugin is retracted
 			# and therefore it should not be built.

plugins/HostLinux.cpp

@@ -5,7 +5,7 @@
 
 #include "HostLinux.h"
 
-#include "mumble_plugin_utils.h"
+#include "mumble_positional_audio_utils.h"
 
 #include <cstring>
 #include <sstream>

plugins/HostWindows.cpp

@@ -5,7 +5,7 @@
 
 #include "HostWindows.h"
 
-#include "mumble_plugin_utils.h"
+#include "mumble_positional_audio_utils.h"
 
 #include <windows.h>
 #include <tlhelp32.h>