cmake, autotools: Add find package config support for cmake clients

With this support cmake and autotools generates cmake equivalent of
pkgconfig files on configure time named DBus1Config*.cmake. These
files are installed into the related directory where cmake expects
find_package related config files.

For instructions how to use this feature with clients see readme.cmake.

With previous DBus versions each cmake client using DBus as dependency
needed a related FindDBus*.cmake in its source distribution or in
the cmake binary packages. With the 'config' find package style support
provided by this patch this requirement has been removed.

The generated config file uses pkgconfig on unix or autotools to
fetch package build flags, which is the prefered way. On Windows
we do not want to require CMake users to have pkg-config installed
so it uses cmake buildin target export support for exporting all
targets into DBus1ConfigTargets*.cmake.

[smcv: make sure variable substitution works in Autotools too]

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=99721
Reviewed-by: Simon McVittie <smcv@collabora.com>
Reviewed-by: Ralf Habacker <ralf.habacker@freenet.de>
Signed-off-by: Simon McVittie <smcv@collabora.com>

4 files changed, 117 insertions, 1 deletions

diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index b62ee656..1d08c6a5 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -104,7 +104,7 @@ set(DBUS_DATADIR             ${CMAKE_INSTALL_FULL_DATADIR})
 #enable building of shared library
 SET(BUILD_SHARED_LIBS ON)
 
-set(INSTALL_TARGETS_DEFAULT_ARGS  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
+set(INSTALL_TARGETS_DEFAULT_ARGS EXPORT DBus1Targets RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
 
 if (CYGWIN)
    set (WIN32)
@@ -523,6 +523,26 @@ endif()
 
 add_definitions(-DHAVE_CONFIG_H=1)
 
+#
+# create cmake find_package related files
+#
+set(INSTALL_CMAKE_DIR ${CMAKE_INSTALL_LIBDIR}/cmake/DBus1)
+if(WIN32)
+   configure_file(DBus1Config.cmake.in "${CMAKE_BINARY_DIR}/DBus1Config.cmake" @ONLY)
+else()
+   configure_file(DBus1Config.pkgconfig.in "${CMAKE_BINARY_DIR}/DBus1Config.cmake" @ONLY)
+endif()
+configure_file(DBus1ConfigVersion.cmake.in "${CMAKE_BINARY_DIR}/DBus1ConfigVersion.cmake" @ONLY)
+install(FILES
+    "${CMAKE_BINARY_DIR}/DBus1Config.cmake"
+    "${CMAKE_BINARY_DIR}/DBus1ConfigVersion.cmake"
+    DESTINATION "${INSTALL_CMAKE_DIR}" COMPONENT dev
+)
+
+if(WIN32)
+    install(EXPORT DBus1Targets DESTINATION "${INSTALL_CMAKE_DIR}" COMPONENT dev)
+endif()
+
 ########### subdirs ###############
 
 add_subdirectory( dbus )
diff --git a/cmake/DBus1Config.cmake.in b/cmake/DBus1Config.cmake.in
new file mode 100644
index 00000000..c389d5ea
--- /dev/null
+++ b/cmake/DBus1Config.cmake.in
@@ -0,0 +1,37 @@
+# - Config file for the DBus1 package
+# It defines the following variables
+#  DBus1_FOUND - Flag for indicating that DBus1 package has been found
+#  DBus1_DEFINITIONS  - compile definitions for DBus1 [1]
+#  DBus1_INCLUDE_DIRS - include directories for DBus1 [1]
+#  DBus1_LIBRARIES    - cmake targets to link against
+
+# [1] This variable is not required if DBus1_LIBRARIES is added
+#     to a target with target_link_libraries
+
+# Compute paths
+if(@DBUS_RELOCATABLE@)
+    get_filename_component(DBus1_INSTALL_DIR "${CMAKE_CURRENT_LIST_DIR}/../../.." ABSOLUTE)
+else()
+    set(DBus1_INSTALL_DIR "@DBUS_PREFIX@")
+endif()
+# Our library dependencies (contains definitions for IMPORTED targets)
+if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/DBus1Targets.cmake")
+    # do not additional search paths for implicit libraries
+    # see https://cmake.org/cmake/help/v3.0/policy/CMP0003.html
+    if(COMMAND cmake_policy)
+        cmake_policy(SET CMP0003 NEW)
+    endif(COMMAND cmake_policy)
+
+    if(NOT TARGET dbus-1)
+        include("${CMAKE_CURRENT_LIST_DIR}/DBus1Targets.cmake")
+    endif()
+
+    set(DBus1_INCLUDE_DIRS "${DBus1_INSTALL_DIR}/@CMAKE_INSTALL_INCLUDEDIR@/dbus-1.0" "${DBus1_INSTALL_DIR}/@CMAKE_INSTALL_LIBDIR@/dbus-1.0/include")
+    set(DBus1_DEFINITIONS)
+    set(DBus1_LIBRARIES dbus-1)
+
+    set_property(TARGET dbus-1 PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${DBus1_INCLUDE_DIRS})
+    set_property(TARGET dbus-1 PROPERTY INTERFACE_COMPILE_DEFINITIONS ${DBus1_DEFINITIONS})
+else()
+    message(FATAL_ERROR "Incomplete cmake support in DBus1 find_package configuration")
+endif()
diff --git a/cmake/DBus1Config.pkgconfig.in b/cmake/DBus1Config.pkgconfig.in
new file mode 100644
index 00000000..7e090aa5
--- /dev/null
+++ b/cmake/DBus1Config.pkgconfig.in
@@ -0,0 +1,48 @@
+# - Config file for the DBus1 package
+# It defines the following variables
+#  DBus1_FOUND - Flag for indicating that DBus1 package has been found
+#  DBus1_DEFINITIONS  - compile definitions for DBus1 [1]
+#  DBus1_INCLUDE_DIRS - include directories for DBus1 [1]
+#  DBus1_LIBRARIES    - cmake targets to link against
+
+# [1] This variable is not required if DBus1_LIBRARIES is added
+#     to a target with target_link_libraries
+
+get_filename_component(DBus1_PKGCONFIG_DIR "${CMAKE_CURRENT_LIST_DIR}/../../pkgconfig" ABSOLUTE)
+find_package(PkgConfig)
+set(ENV{PKG_CONFIG_DIR})
+set(ENV{PKG_CONFIG_PATH} ${DBus1_PKGCONFIG_DIR})
+set(ENV{PKG_CONFIG_LIBDIR} ${DBus1_PKGCONFIG_DIR})
+# for debugging
+#set(ENV{PKG_CONFIG_DEBUG_SPEW} 1)
+pkg_check_modules(PC_DBUS1 QUIET dbus-1)
+set(DBus1_DEFINITIONS ${PC_DBUS1_CFLAGS_OTHER})
+
+# find the real stuff and use pkgconfig variables as hints
+# because cmake provides more search options
+find_path(DBus1_INCLUDE_DIR dbus/dbus.h
+    HINTS ${PC_DBUS1_INCLUDEDIR} ${PC_DBUS1_INCLUDE_DIRS}
+    PATH_SUFFIXES dbus-1.0)
+find_path(DBus1_ARCH_INCLUDE_DIR dbus/dbus-arch-deps.h
+    HINTS ${PC_DBUS1_INCLUDE_DIRS}
+    PATH_SUFFIXES dbus-1.0)
+find_library(DBus1_LIBRARY NAMES ${PC_DBUS1_LIBRARIES}
+    HINTS ${PC_DBUS1_LIBDIR} ${PC_DBUS1_LIBRARY_DIRS})
+
+include(FindPackageHandleStandardArgs)
+# handle the QUIETLY and REQUIRED arguments and set DBus1_FOUND to TRUE
+# if all listed variables are TRUE
+find_package_handle_standard_args(DBus1 DEFAULT_MSG
+    DBus1_LIBRARY DBus1_INCLUDE_DIR DBus1_ARCH_INCLUDE_DIR)
+
+# make the mentioned variables only visible in cmake gui with "advanced" enabled
+mark_as_advanced(DBus1_INCLUDE_DIR DBus1_LIBRARY)
+
+set(DBus1_LIBRARIES dbus-1)
+set(DBus1_INCLUDE_DIRS "${DBus1_INCLUDE_DIR}" "${DBus1_ARCH_INCLUDE_DIR}")
+
+# setup imported target
+add_library(dbus-1 SHARED IMPORTED)
+set_property(TARGET dbus-1 APPEND PROPERTY IMPORTED_LOCATION ${DBus1_LIBRARY})
+set_property(TARGET dbus-1 APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${DBus1_INCLUDE_DIRS})
+set_property(TARGET dbus-1 APPEND PROPERTY INTERFACE_COMPILE_DEFINITIONS ${DBus1_DEFINITIONS})
diff --git a/cmake/DBus1ConfigVersion.cmake.in b/cmake/DBus1ConfigVersion.cmake.in
new file mode 100644
index 00000000..239bf593
--- /dev/null
+++ b/cmake/DBus1ConfigVersion.cmake.in
@@ -0,0 +1,11 @@
+set(PACKAGE_VERSION @DBUS_VERSION@)
+
+# Check whether the requested PACKAGE_FIND_VERSION is compatible
+if("${PACKAGE_VERSION}" VERSION_LESS "${PACKAGE_FIND_VERSION}")
+  set(PACKAGE_VERSION_COMPATIBLE FALSE)
+else()
+  set(PACKAGE_VERSION_COMPATIBLE TRUE)
+  if ("${PACKAGE_VERSION}" VERSION_EQUAL "${PACKAGE_FIND_VERSION}")
+    set(PACKAGE_VERSION_EXACT TRUE)
+  endif()
+endif()