cmakemodules/git_helper.cmake

# Execute git command and return the output
Function ( GitExecute COMMAND FORCE OUT_RESULT OUT_SUCCESS )
    Set ( ${OUT_SUCCESS} 1 PARENT_SCOPE )
    Execute_Process ( COMMAND
                        bash -c "${COMMAND}"
                      RESULT_VARIABLE
                        GIT_RET
                      OUTPUT_VARIABLE
                        GIT_REV
                      ERROR_VARIABLE
                        GIT_ERR )
    If (    NOT ${GIT_RET} EQUAL 0
         OR NOT "${GIT_ERR}" STREQUAL "" )
        If ( FORCE )
            Message ( FATAL_ERROR "Unable to execute git command (command=${COMMAND} out=${GIT_REV}; err=${GIT_ERR}; ret=${GIT_RET})" )
        Else ( )
            Set ( ${OUT_SUCCESS} 0 PARENT_SCOPE )
        EndIf ( )
    EndIf ( )
    Set ( ${OUT_RESULT} "${GIT_REV}" PARENT_SCOPE )
EndFunction ( )

# Get the version by reading the git tag
Function ( GitGetVersion GIT_ROOT OUT_MAJOR OUT_MINOR OUT_PATCH OUT_BUILD OUT_HASH OUT_BEHIND OUT_DIRTY )

    If ( NOT EXISTS "${GIT_ROOT}/.git" )
        Return ( )
    EndIf ( )

    # Find the latest git tag
    GitExecute ( "git describe --tags --abbrev=1 --match v[0-9].[0-9]* HEAD" False TAG SUCCESS )
    If ( NOT ${SUCCESS} )
        Return ( )
    EndIf ( )

    GitExecute ( "git status -s -uall" True DIRTY SUCCESS )
    If ( NOT ${SUCCESS} )
        Return ( )
    EndIf ( )

    GitExecute ( "git rev-parse HEAD" True HASH SUCCESS )
    If ( NOT ${SUCCESS} )
        Return ( )
    EndIf ( )

    # Split the git revision string
    String ( REGEX REPLACE "^v" "" TAG "${TAG}" )
    String ( REPLACE "-" ";" SPLIT "${TAG}" )
    List ( LENGTH SPLIT COUNT )
    If ( ${COUNT} LESS 2 )
        Message ( FATAL_ERROR "Unable to split git tag into it's sub components: ${TAG}!" )
    EndIf ( )
    List ( GET SPLIT 0 VERSION )
    List ( GET SPLIT 1 BEHIND )

    # Split the version
    String ( STRIP "${VERSION}" SPLIT )
    String ( REPLACE "." ";" SPLIT "${SPLIT}" )
    List ( LENGTH SPLIT COUNT )
    If ( ${COUNT} LESS 2 )
        Message ( FATAL_ERROR "Unable to split version string: ${VERSION}!" )
    EndIf ( )

    # major
    List ( GET SPLIT 0 TMP )
    Set ( ${OUT_MAJOR} ${TMP} PARENT_SCOPE )

    # minor
    List ( GET SPLIT 1 TMP )
    Set ( ${OUT_MINOR} ${TMP} PARENT_SCOPE )

    # patch
    If ( ${COUNT} GREATER 2 )
        List ( GET SPLIT 2 TMP )
        Set ( ${OUT_PATCH} ${TMP} PARENT_SCOPE )
    EndIf ( )

    # build
    If ( ${COUNT} GREATER 3 )
        List ( GET SPLIT 3 TMP )
        Set ( ${OUT_BUILD} ${TMP} PARENT_SCOPE )
    EndIf ( )

    # hash
    String ( STRIP "${HASH}" HASH )
    Set ( ${OUT_HASH} ${HASH} PARENT_SCOPE )

    # behind
    Set ( ${OUT_BEHIND} ${BEHIND} PARENT_SCOPE )

    # dirty
    If ( DIRTY )
        Set ( ${OUT_DIRTY} 1 PARENT_SCOPE )
    Else ( )
        Set ( ${OUT_DIRTY} 0 PARENT_SCOPE )
    EndIf ( )

EndFunction ( )