X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=version.sh;h=92edcb9474ed86d641b2b2252f40f9c80399facb;hb=eb87d1f6784fb488b95fb0932c0367e8d9d0418d;hp=62882e0f361fe163d084f633b69490c6aab62669;hpb=a3b9f53d7b2faa0d60fa2308351c5aef3381630f;p=ffmpeg

diff --git a/version.sh b/version.sh
index 62882e0f361..92edcb9474e 100755
--- a/version.sh
+++ b/version.sh
@@ -1,5 +1,7 @@
 #!/bin/sh
 
+# Usage: version.sh <ffmpeg-root-dir> <output-version.h> <extra-version>
+
 # check for git short hash
 if ! test "$revision"; then
     revision=$(cd "$1" && git describe --tags --match N 2> /dev/null)
@@ -40,9 +42,17 @@ if [ -z "$2" ]; then
 fi
 
 NEW_REVISION="#define FFMPEG_VERSION \"$version\""
-OLD_REVISION=$(cat "$2" 2> /dev/null)
+OLD_REVISION=$(cat "$2" 2> /dev/null | head -3 | tail -1)
+
+# String used for preprocessor guard
+GUARD=$(echo "$2" | sed 's/\//_/' | sed 's/\./_/' | tr '[:lower:]' '[:upper:]' | sed 's/LIB//')
 
 # Update version header only on revision changes to avoid spurious rebuilds
 if test "$NEW_REVISION" != "$OLD_REVISION"; then
-    echo "$NEW_REVISION" > "$2"
+    cat << EOF > "$2"
+#ifndef $GUARD
+#define $GUARD
+$NEW_REVISION
+#endif /* $GUARD */
+EOF
 fi