CMake: use a dedicated variable to hold a path to the CFS source folder

This is needed when CFE's root CMakeLists.txt is not the highest level
CMakeLists.txt in the project.

CMakeLists.txt

@@ -49,7 +49,7 @@ set(CMAKE_LEGACY_CYGWIN_WIN32 0)
 # Add a path for any locally-supplied CMake modules
 # These would typically be a part of any custom PSPs in use.
 # (this is not required, and the directory can be empty/nonexistent)
-set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/../psp/cmake/Modules" ${CMAKE_MODULE_PATH})
+set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../psp/cmake/Modules" ${CMAKE_MODULE_PATH})
 
 # The minimum CMake version is chosen because 2.6.4 is what is
 # included by default with RHEL/Centos 5.x
@@ -59,7 +59,8 @@ cmake_minimum_required(VERSION 2.6.4)
 # that the subdirectories will at least use the "C" language, so
 # indicate that now.  Doing this early initializes the CFLAGS
 # so they won't change later.
-project(CFETOP C)
+# Note: this line defines the CFE_SOURCE_DIR variable.
+project(CFE C)
 
 # Allow unit tests to be added by any recipe
 enable_testing()

cmake/mission_build.cmake

@@ -36,7 +36,7 @@ function(initialize_globals)
     # this is the parent (mission) build and variable values must be determined
     # Obtain the "real" top-level source directory and set it in parent scope
     if (NOT DEFINED MISSION_SOURCE_DIR)
-      get_filename_component(MISSION_SOURCE_DIR "${CMAKE_SOURCE_DIR}/.." ABSOLUTE)
+      get_filename_component(MISSION_SOURCE_DIR "${CFE_SOURCE_DIR}/.." ABSOLUTE)
       set(MISSION_SOURCE_DIR ${MISSION_SOURCE_DIR} CACHE PATH "Top level mission source directory")
     endif(NOT DEFINED MISSION_SOURCE_DIR)
 
@@ -211,13 +211,13 @@ function(prepare)
   file(WRITE "${CMAKE_BINARY_DIR}/doc/mission-content.doxyfile"
       ${MISSION_DOXYFILE_USER_CONTENT})
 
-  configure_file("${CMAKE_SOURCE_DIR}/cmake/cfe-common.doxyfile.in"
+  configure_file("${CFE_SOURCE_DIR}/cmake/cfe-common.doxyfile.in"
     "${CMAKE_BINARY_DIR}/doc/cfe-common.doxyfile")
 
- configure_file("${CMAKE_SOURCE_DIR}/cmake/osal-common.doxyfile.in"
+  configure_file("${CFE_SOURCE_DIR}/cmake/osal-common.doxyfile.in"
     "${CMAKE_BINARY_DIR}/doc/osal-common.doxyfile")
 
-  configure_file("${CMAKE_SOURCE_DIR}/cmake/mission-detaildesign.doxyfile.in"
+  configure_file("${CFE_SOURCE_DIR}/cmake/mission-detaildesign.doxyfile.in"
     "${CMAKE_BINARY_DIR}/doc/mission-detaildesign.doxyfile")
 
   # The user guide should include the doxygen from the _public_ API files from CFE + OSAL
@@ -247,10 +247,10 @@ function(prepare)
   set(OSALGUIDE_PREDEFINED 
       "MESSAGE_FORMAT_IS_CCSDS")
 
-  configure_file("${CMAKE_SOURCE_DIR}/cmake/cfe-usersguide.doxyfile.in"
+  configure_file("${CFE_SOURCE_DIR}/cmake/cfe-usersguide.doxyfile.in"
     "${CMAKE_BINARY_DIR}/doc/cfe-usersguide.doxyfile")
 
-  configure_file("${CMAKE_SOURCE_DIR}/cmake/osalguide.doxyfile.in"
+  configure_file("${CFE_SOURCE_DIR}/cmake/osalguide.doxyfile.in"
     "${CMAKE_BINARY_DIR}/doc/osalguide.doxyfile")  
 
   add_custom_target(mission-doc 
@@ -302,7 +302,7 @@ function(prepare)
   add_custom_target(mission-version
     COMMAND 
         ${CMAKE_COMMAND} -D BIN=${CMAKE_BINARY_DIR}
-                         -P ${CMAKE_SOURCE_DIR}/cmake/version.cmake
+                         -P ${CFE_SOURCE_DIR}/cmake/version.cmake
     WORKING_DIRECTORY 
       ${CMAKE_SOURCE_DIR}                             
   )
@@ -345,8 +345,8 @@ function(process_arch TARGETSYSTEM)
     # Find the toolchain file - allow a file in the mission defs dir to supercede one in the compile dir
     if (EXISTS ${MISSION_DEFS}/toolchain-${CURRSYS}.cmake)
       set(TOOLCHAIN_FILE ${MISSION_DEFS}/toolchain-${CURRSYS}.cmake)
-    elseif(EXISTS ${CMAKE_SOURCE_DIR}/cmake/toolchain-${CURRSYS}.cmake)
-      set(TOOLCHAIN_FILE ${CMAKE_SOURCE_DIR}/cmake/toolchain-${CURRSYS}.cmake)
+    elseif(EXISTS ${CFE_SOURCE_DIR}/cmake/toolchain-${CURRSYS}.cmake)
+      set(TOOLCHAIN_FILE ${CFE_SOURCE_DIR}/cmake/toolchain-${CURRSYS}.cmake)
     else()
       message(FATAL_ERROR "Unable to find toolchain file for ${CURRSYS}")
     endif()
@@ -365,7 +365,7 @@ function(process_arch TARGETSYSTEM)
         -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
         -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
         ${SELECTED_TOOLCHAIN_FILE}
-        ${CMAKE_SOURCE_DIR} 
+        ${CFE_SOURCE_DIR}
     WORKING_DIRECTORY 
         "${ARCH_BINARY_DIR}" 
     RESULT_VARIABLE