+# this is a wrapper for doing lock functions.
+#
+# it lets us depend on either lockfile-progs (preferred) or procmail's
+# lockfile, and should
+lock() {
+ local use_lockfileprogs=true
+ local action="$1"
+ local file="$file"
+
+ if ! ( which lockfile-create >/dev/null 2>/dev/null ) ; then
+ if ! ( which lockfile >/dev/null ); then
+ failure "Neither lockfile-create nor lockfile are in the path!"
+ use_lockfileprogs=
+ fi
+
+ case "$action" in
+ create)
+ if [ -n "$use_lockfileprogs" ] ; then
+ lockfile-create "$file" || failure "unable to lock '$file'"
+ else
+ lockfile -r 20 "${file}.lock" || failure "unable to lock '$file'"
+ fi
+ ;;
+ touch)
+ if [ -n "$use_lockfileprogs" ] ; then
+ lockfile-touch "$file"
+ else
+ # Nothing to do here
+ fi
+ ;;
+ remove)
+ if [ -n "$use_lockfileprogs" ] ; then
+ lockfile-remove "$file"
+ else
+ rm -f "${file}.lock"
+ fi
+ ;;
+ *)
+ failure "bad argument for lock subfunction '$action'"
+ esac
+}
+