[BUILD] Fix build issue if version information (Git tag) is missing

The software version for packaging purposes is consituted from the
following rules:

  - If the version information (from Git tags or the embedded version
    header file) is available, the version number for the packaging is
    set to those found version information.
  - If there isn't any version information available (e.g. missing Git
    tags), the version number for the packaging is set to '0.0' to
    represent an unkown version number.

2 files changed, 57 insertions, 15 deletions

diff --git a/cmake/GenerateVersion.cmake b/cmake/GenerateVersion.cmake
index e7c551b..bddd672 100644
--- a/cmake/GenerateVersion.cmake
+++ b/cmake/GenerateVersion.cmake
@@ -11,7 +11,7 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH}
 include(Version)
 
 # get Git version of Git repository
-get_repository_version(DNBD3_VERSION ${VERSION_INPUT_FILE} ${VERSION_BUILD_TYPE} ${GIT_EXECUTABLE} ${REPOSITORY_DIR})
+get_repository_version(DNBD3_VERSION DNBD3_BRANCH ${VERSION_INPUT_FILE} ${VERSION_BUILD_TYPE} ${GIT_EXECUTABLE} ${REPOSITORY_DIR})
 
 # generate version header if header does not exists
 if(NOT EXISTS ${VERSION_INPUT_FILE})
diff --git a/cmake/Version.cmake b/cmake/Version.cmake
index 9beb338..8a6a2fd 100644
--- a/cmake/Version.cmake
+++ b/cmake/Version.cmake
@@ -31,40 +31,82 @@ macro(gen_project_version VERSION_INPUT_FILE VERSION_INPUT_FILE_TEMPLATE VERSION
 endmacro(gen_project_version VERSION_INPUT_FILE VERSION_INPUT_FILE_TEMPLATE VERSION_OUTPUT_FILE)
 
 # macro to get Git version information
-macro(get_repository_version REPOSITORY_VERSION VERSION_HEADER_FILE VERSION_BUILD_TYPE GIT_EXECUTABLE REPOSITORY_DIR)
+macro(get_repository_version REPOSITORY_VERSION REPOSITORY_BRANCH VERSION_HEADER_FILE VERSION_BUILD_TYPE GIT_EXECUTABLE REPOSITORY_DIR)
+    # set empty Git version information
+    set(GIT_VERSION "")
+    # set empty Git branch information
+    set(GIT_BRANCH "")
+
     # check if generated version header from source package is available
     if(EXISTS ${VERSION_HEADER_FILE})
         # get version information from the generated version header of the source package
-        file(READ ${VERSION_HEADER_FILE} GIT_VERSION)
-        string(REGEX MATCH "DNBD3_VERSION[ \t]+\"([0-9][A-Za-z0-9.+~-]*)\"" GIT_VERSION ${GIT_VERSION})
+        file(READ ${VERSION_HEADER_FILE} GIT_VERSION_VERBOSE)
+        string(REGEX MATCH "DNBD3_VERSION[ \t]+\"([0-9][A-Za-z0-9.+~-]*)\"" GIT_VERSION ${GIT_VERSION_VERBOSE})
         set(GIT_VERSION "${CMAKE_MATCH_1}")
+
+        # get branch information from the generated version header of the source package
+        file(READ ${VERSION_HEADER_FILE} GIT_BRANCH_VERBOSE)
+        string(REGEX MATCH "DNBD3_BRANCH[ \t]+\"([0-9][A-Za-z0-9.+~-]*)\"" GIT_BRANCH ${GIT_BRANCH_VERBOSE})
+        set(GIT_BRANCH "${CMAKE_MATCH_1}")
     else(EXISTS ${VERSION_HEADER_FILE})
         # get detailed Git version information from Git repository
         execute_process(COMMAND ${GIT_EXECUTABLE} describe HEAD
                         WORKING_DIRECTORY ${REPOSITORY_DIR}
-                        OUTPUT_VARIABLE GIT_VERSION
-                        OUTPUT_STRIP_TRAILING_WHITESPACE)
-        execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse --abbrev-ref HEAD
-                        WORKING_DIRECTORY ${REPOSITORY_DIR}
-                        OUTPUT_VARIABLE GIT_BRANCH
+                        OUTPUT_VARIABLE GIT_VERSION_VERBOSE
+                        RESULT_VARIABLE GIT_RETURN_CODE
+                        ERROR_QUIET
                         OUTPUT_STRIP_TRAILING_WHITESPACE)
 
+        # parse version information from repository if Git command succeeds
+        if(GIT_RETURN_CODE EQUAL 0)
+            # remove the first letter of the version to satisfy packaging rules
+            string(REGEX MATCH "([0-9]+:)?[0-9][A-Za-z0-9.+~-]*" GIT_VERSION ${GIT_VERSION_VERBOSE})
+        endif(GIT_RETURN_CODE EQUAL 0)
+
         # overwrite version from Git if version is unknown
         if(GIT_VERSION STREQUAL "")
-            set(GIT_VERSION "unknown")
+            # overwrite version information with unknown version 'v0.0'
+            set(GIT_VERSION "0.0")
+
+            # print a message in Release build configuration to warn about the unknown version
+            if(${VERSION_BUILD_TYPE} MATCHES "Release")
+                message(WARNING "The version information from Git tags in this dnbd3 Git repository is missing! Please fetch all Git tags of this repository for a ${VERSION_BUILD_TYPE} build!")
+            endif(${VERSION_BUILD_TYPE} MATCHES "Release")
         endif(GIT_VERSION STREQUAL "")
+
+        # get current branch of Git repository
+        execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse --abbrev-ref HEAD
+                        WORKING_DIRECTORY ${REPOSITORY_DIR}
+                        OUTPUT_VARIABLE GIT_BRANCH_VERBOSE
+                        RESULT_VARIABLE GIT_RETURN_CODE
+                        ERROR_QUIET
+                        OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+        # check output to get branch information
+        if(GIT_RETURN_CODE EQUAL 0)
+            set(GIT_BRANCH ${GIT_BRANCH_VERBOSE})
+        endif(GIT_RETURN_CODE EQUAL 0)
+
         if(GIT_BRANCH STREQUAL "")
+            # overwrite branch information with 'unknown' branch
             set(GIT_BRANCH "unknown")
+
+            # print a message in Release build configuration to warn about the unknown branch
+            if(${VERSION_BUILD_TYPE} MATCHES "Release")
+                message(WARNING "The current branch in the dnbd3 Git repository is unknown! Please check the branches of this repository for a ${VERSION_BUILD_TYPE} build!")
+            endif(${VERSION_BUILD_TYPE} MATCHES "Release")
         endif(GIT_BRANCH STREQUAL "")
 
         # get status of Git repository
         execute_process(COMMAND ${GIT_EXECUTABLE} status --porcelain
                         WORKING_DIRECTORY ${REPOSITORY_DIR}
                         OUTPUT_VARIABLE GIT_STATUS
+                        RESULT_VARIABLE GIT_RETURN_CODE
+                        ERROR_QUIET
                         OUTPUT_STRIP_TRAILING_WHITESPACE)
 
         # check if Git repository is dirty
-        if(NOT GIT_STATUS STREQUAL "")
+        if(GIT_RETURN_CODE EQUAL 0 AND NOT GIT_STATUS STREQUAL "")
             # the Git repository is dirty, thus extend the version information
             set(GIT_VERSION "${GIT_VERSION}+MOD")
 
@@ -72,10 +114,10 @@ macro(get_repository_version REPOSITORY_VERSION VERSION_HEADER_FILE VERSION_BUIL
             if(${VERSION_BUILD_TYPE} MATCHES "Release")
                 message(WARNING "This dnbd3 Git repository is dirty! Please commit or revert all changes for a ${VERSION_BUILD_TYPE} build!")
             endif(${VERSION_BUILD_TYPE} MATCHES "Release")
-        endif(NOT GIT_STATUS STREQUAL "")
+        endif(GIT_RETURN_CODE EQUAL 0 AND NOT GIT_STATUS STREQUAL "")
     endif(EXISTS ${VERSION_HEADER_FILE})
 
-    # remove the first letter of the version to satisfy packaging rules
-    # and return to caller
-    string(REGEX MATCH "([0-9]+:)?[0-9][A-Za-z0-9.+~-]*" ${REPOSITORY_VERSION} ${GIT_VERSION})
+    # return version and branch to caller
+    set(${REPOSITORY_VERSION} ${GIT_VERSION})
+    set(${REPOSITORY_BRANCH} ${GIT_BRANCH})
 endmacro(get_repository_version)