avoid unneeded rebuilds due to component version

if the component version file does not change, don't touch it
and force a rebuild

(cherry picked from commit 86f7ac2f57591cf72ae22f8d1267efcc8e0b6641)

Change-Id: Ia6e7b3f10e7efdea3e46c4fb7634f6e28d624e58
Reviewed-on: http://gerrit.openafs.org/4081
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>

diff --git a/src/config/Makefile.version-NOCML.in b/src/config/Makefile.version-NOCML.in
index 7aba6ea50f71239881b5fc2be5b3d8d501b37a32..18dcbc672900bc65430c362fada8bfffc829d24a 100644 (file)
--- a/src/config/Makefile.version-NOCML.in
+++ b/src/config/Makefile.version-NOCML.in
@@ -10,9 +10,12 @@ PACKAGE=@PACKAGE@
 AFS_component_version_number.o: AFS_component_version_number.c
 
 AFS_component_version_number.c: @TOP_OBJDIR@/src/config/Makefile.version
-       VERSION=`@abs_top_srcdir@/build-tools/git-version @abs_top_srcdir@ "@VERSION@"` && \
-       echo 'char cml_version_number[]="@(#) OpenAFS '$$VERSION' built ' `date +"%Y-%m-%d"` '";' >AFS_component_version_number.c && \
-       echo 'char* AFSVersion = "${PACKAGE} '$$VERSION'";' >>AFS_component_version_number.c
+       ( VERSION=`@abs_top_srcdir@/build-tools/git-version @abs_top_srcdir@ "@VERSION@"` && \
+       echo 'char cml_version_number[]="@(#) OpenAFS '$$VERSION' built ' `date +"%Y-%m-%d"` '";' >AFS_component_version_number.c.NEW && \
+       echo 'char* AFSVersion = "${PACKAGE} '$$VERSION'";' >>AFS_component_version_number.c.NEW && \
+       if cmp AFS_component_version_number.c.NEW AFS_component_version_number.c > /dev/null ; then : ; else \
+       mv AFS_component_version_number.c.NEW AFS_component_version_number.c ; fi )
+       rm -f AFS_component_version_number.c.NEW
 
 version.xml:
        VERSION=`@abs_top_srcdir@/build-tools/git-version @abs_top_srcdir@ "@VERSION@"` && \