Update version string setting proceedure

Package maintainers can override the git repo detection by providing
their own release version string using cmake -DRELEASE_STRING="you_version"
For all other users we check for a git repo and default to the last release
version string if none is found

cmake/set_release.cmake

@@ -1,26 +1,35 @@
-set(LATEST_RELEASE "2017-03-R2")
+# This script controls the version string that is passed at compile time.
+# To override the version, use cmake -DRELEASE_STRING="you_version"
+# If RELEASE_STRING is not explicitly set we attempt to use the latest git
+# commit.  If cmake isn't being run from within a git repository we use the
+# LATEST_RELEASE variable, which developers should set before a release is
+# tagged
+
+if(NOT DEFINED RELEASE_STRING)
+	set(LATEST_RELEASE "2017-03-R2")
 
-execute_process(
-        COMMAND git log -n 1 --format=%h
-        WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
-        RESULT_VARIABLE GIT_EXIT_ERROR
-        ERROR_QUIET
-        OUTPUT_VARIABLE GIT_VERSION
-        OUTPUT_STRIP_TRAILING_WHITESPACE
-)
-if (GIT_EXIT_ERROR)
-	# We're probably not in a git repo
-	set(RELEASE ${LATEST_RELEASE})
-else (GIT_EXIT_ERROR)
-	# We're in a git repo
 	execute_process(
-		COMMAND git status -s --untracked-files=no
-		OUTPUT_VARIABLE DIRTY
+		COMMAND git log -n 1 --format=%h
+		WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+		RESULT_VARIABLE GIT_EXIT_ERROR
+		ERROR_QUIET
+		OUTPUT_VARIABLE GIT_VERSION
+		OUTPUT_STRIP_TRAILING_WHITESPACE
 	)
-	if ( NOT "${DIRTY}" STREQUAL "" )
-		set(DIRTY_FLAG "*")
-	else()
-		set(DIRTY_FLAG "")
-	endif()
-        set(RELEASE "git-${GIT_VERSION}${DIRTY_FLAG}")
-endif (GIT_EXIT_ERROR)
+	if (GIT_EXIT_ERROR)
+		# We're probably not in a git repo
+		set(RELEASE_STRING ${LATEST_RELEASE})
+	else (GIT_EXIT_ERROR)
+		# We're in a git repo
+		execute_process(
+			COMMAND git status -s --untracked-files=no
+			OUTPUT_VARIABLE DIRTY
+		)
+		if ( NOT "${DIRTY}" STREQUAL "" )
+			set(DIRTY_FLAG "*")
+		else()
+			set(DIRTY_FLAG "")
+		endif()
+		set(RELEASE_STRING "git-${GIT_VERSION}${DIRTY_FLAG}")
+	endif (GIT_EXIT_ERROR)
+endif(NOT DEFINED RELEASE_STRING)

lib/src/CMakeLists.txt

@@ -19,8 +19,8 @@
 # Based slightly upon the hackrf cmake setup.
 
 include(${PROJECT_SOURCE_DIR}/../cmake/set_release.cmake)
-add_definitions( -DRELEASE="${RELEASE}" )
-message(STATUS "Setting version string ${RELEASE}")
+add_definitions( -DRELEASE="${RELEASE_STRING}" )
+message(STATUS "Setting version string ${RELEASE_STRING}")
 
 # Source
 set(c_sources ${CMAKE_CURRENT_SOURCE_DIR}/bluetooth_packet.c