+# The newest revision that should not appear in the generated ChangeLog.
+gen_origin=
+
+force=
+output=ChangeLog
+nmax=2
+
+while [ $# -gt 0 ]; do
+ case "$1" in
+ -g|--gen-origin) gen_origin="$2" ; shift ;;
+ -f|--force) force=1 ;;
+ -n|--nmax) nmax="$2"; shift ;;
+ -o|--output) output="$2" ; shift ;;
+ *) echo "Unrecognized argument: $1" >&2; exit 1 ;;
+ esac
+ shift
+done
+
+if [ ! -f ChangeLog.$nmax ]; then
+ echo "Can't find ChangeLog.$nmax" >&2
+ echo "Must be run from the top source directory" >&2
+ exit 1
+fi
+
+# If not specified in the command line, get gen_origin from the existing
+# ChangeLog file.
+[ "$gen_origin" ] || {
+ gen_origin_line=`
+ grep -E '^commit [0-9a-f]+ [(]inclusive[)]' ChangeLog.$nmax
+ ` || {
+ echo "ChangeLog.$nmax lacks a 'commit ... (inclusive)' line" >&2
+ exit 1
+ }
+ set $gen_origin_line
+ gen_origin=$2
+}
+
+# Get the new value for gen_origin from the latest version in the repository.
+new_origin=`git log --pretty=format:%H 'HEAD^!'` || exit
+
+if [ -f "$output" ]; then
+ [ ! "$force" ] && echo "$output exists" >&2 && exit 1
+ rm -f "$output" || exit 1
+fi