Add Findepoll.cmake

- On FreeBSD epoll.h if provided through a library (from a port, epoll-shim)
  that emulates the Linux behavior. Make a CMake module for it to hide
  differences in systems behind a module.
- Find epoll on FreeBSD and link to it

Now on FreeBSD, tries to compile virtual_terminal.cpp, which will fail because
that needs more patches.

CMakeLists.txt

@@ -309,6 +309,14 @@ set_package_properties(QAccessibilityClient PROPERTIES
 )
 set(HAVE_ACCESSIBILITY ${QAccessibilityClient_FOUND})
 
+if(CMAKE_SYSTEM MATCHES "FreeBSD")
+    find_package(epoll)
+    set_package_properties(epoll PROPERTIES DESCRIPTION "I/O event notification facility"
+        TYPE REQUIRED
+        PURPOSE "Needed for running kwin_wayland"
+    )
+endif()
+
 include(ECMQMLModules)
 ecm_find_qmlmodule(QtQuick 2.3)
 ecm_find_qmlmodule(QtQuick.Controls 1.2)
@@ -578,6 +586,13 @@ if (HAVE_LINUX_VT_H)
     )
 endif()
 
+if(CMAKE_SYSTEM MATCHES "FreeBSD")
+    # We know it has epoll, so supports VT as well
+    set(kwin_SRCS ${kwin_SRCS}
+        virtual_terminal.cpp
+    )
+endif()
+
 kconfig_add_kcfg_files(kwin_SRCS settings.kcfgc)
 kconfig_add_kcfg_files(kwin_SRCS colorcorrection/colorcorrect_settings.kcfgc)
 kconfig_add_kcfg_files(kwin_SRCS rulesettings.kcfgc)
@@ -690,6 +705,12 @@ set_target_properties(kwin PROPERTIES
 target_link_libraries(kwin ${kwinLibs} kwinglutils ${epoxy_LIBRARY})
 generate_export_header(kwin EXPORT_FILE_NAME kwin_export.h)
 
+if(CMAKE_SYSTEM MATCHES "FreeBSD")
+    # epoll is required, includes live under ${LOCALBASE}, separate library
+    target_include_directories(kwin PUBLIC ${epoll_INCLUDE_DIRS})
+    target_link_libraries(kwin ${kwinLibs} ${epoll_LIBRARIES}) 
+endif()
+
 add_executable(kwin_x11 main_x11.cpp)
 target_link_libraries(kwin_x11 kwin KF5::Crash Qt5::X11Extras)
 

cmake/modules/Findepoll.cmake

@@ -0,0 +1,78 @@
+#.rest:
+# FindEpoll
+# --------------
+#
+# Try to find epoll or epoll-shim on this system. This finds:
+#  - some shim on Unix like systems (FreeBSD), or
+#  - the kernel's epoll on Linux systems.
+#
+# This will define the following variables:
+#
+# ``epoll_FOUND``
+#    True if epoll is available
+# ``epoll_LIBRARIES``
+#    This has to be passed to target_link_libraries()
+# ``epoll_INCLUDE_DIRS``
+#    This has to be passed to target_include_directories()
+#
+# On Linux, the libraries and include directories are empty,
+# even though epoll_FOUND may be set to TRUE. This is because
+# no special includes or libraries are needed. On other systems
+# these may be needed to use epoll.
+
+#=============================================================================
+# Copyright 2019 Tobias C. Berner <tcberner@FreeBSD.org>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#=============================================================================
+
+find_path(epoll_INCLUDE_DIRS sys/epoll.h PATH_SUFFIXES libepoll-shim)
+
+if(epoll_INCLUDE_DIRS)
+    # On Linux there is no library to link against, on the BSDs there is.
+    # On the BSD's, epoll is implemented through a library, libepoll-shim.
+    if( CMAKE_SYSTEM_NAME MATCHES "Linux")
+        set(epoll_FOUND TRUE)
+        set(epoll_LIBRARIES "")
+        set(epoll_INCLUDE_DIRS "")
+    else()
+        find_library(epoll_LIBRARIES NAMES epoll-shim)
+        include(FindPackageHandleStandardArgs)
+        find_package_handle_standard_args(epoll
+            FOUND_VAR
+                epoll_FOUND
+            REQUIRED_VARS
+                epoll_LIBRARIES
+                epoll_INCLUDE_DIRS
+        )
+        mark_as_advanced(epoll_LIBRARIES epoll_INCLUDE_DIRS)
+        include(FeatureSummary)
+        set_package_properties(epoll PROPERTIES
+            URL "https://github.com/FreeBSDDesktop/epoll-shim"
+            DESCRIPTION "small epoll implementation using kqueue"
+        )
+    endif()
+else()
+   set(epoll_FOUND FALSE)
+endif()
+
+mark_as_advanced(epoll_LIBRARIES epoll_INCLUDE_DIRS)