From c4ea0ea4efe429c9e547bab80096c2c8dbf5cd92 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Thu, 13 Mar 2014 12:18:40 -0500
Subject: [PATCH] properly detect no changed objects

The current solution doesn't work because "$?" will always be 0, even if
there were no "CC" lines in the build log.  Instead, just make sure the
changed_objs file isn't empty.
---
 kpatch-build/kpatch-build | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/kpatch-build/kpatch-build b/kpatch-build/kpatch-build
index e5013b712..9b253e0d4 100755
--- a/kpatch-build/kpatch-build
+++ b/kpatch-build/kpatch-build
@@ -184,11 +184,8 @@ patch -p1 < "$APPLIEDPATCHFILE" >> "$LOGFILE" 2>&1 || die
 make "-j$CPUS" vmlinux "O=$OBJDIR" > "$TEMPDIR/patched_build.log" 2>&1 || die
 
 echo "Detecting changed objects"
-grep CC "$TEMPDIR/patched_build.log" | grep -v init/version.o | awk '{print $2}' >> "$TEMPDIR/changed_objs"
-if [[ $? -ne 0 ]]; then
-	echo "No changed objects"
-	exit 1
-fi
+grep CC "$TEMPDIR/patched_build.log" | grep -v init/version.o | awk '{print $2}' > "$TEMPDIR/changed_objs"
+[[ ! -s "$TEMPDIR/changed_objs" ]] && die "no changed objects were detected"
 
 echo "Rebuilding changed objects"
 rm -rf "$OBJDIR2"