Introduce function for work with cached data

A cache for changes used in the alterator-net-* modules often enough,
so add some common function to alterator-net-functions.

alterator-net-functions/alterator-net-functions

@@ -6,6 +6,7 @@ etcnet_iface_dir=/etc/net/ifaces
 etcnet_default_iface_dir="$etcnet_iface_dir/default"
 resolvconf_rdelim='[[:space:]]\+'
 resolvconf_wdelim=' '
+__iface_removed_tag=".REMOVED"
 
 . alterator-hw-functions
 . shell-config
@@ -710,6 +711,121 @@ iface_down()
     return 1
 }
 
+### cache functions
+iface_will_removed()
+{
+	local cachedir="$1"; shift
+	local ifname="$1"; shift
+
+	[ -n "$cachedir" -a -n "$ifname" -a -f "$cachedir/$ifname/$__iface_removed_tag" ]
+}
+
+# read stdin
+__filter_out_removed_ifaces()
+{
+	local cachedir="$1"; shift
+	local ifname=
+
+	while read ifname; do
+		iface_will_removed "$cachedir" "$ifname" || echo "$ifname"
+	done
+}
+
+ifacedir_with_cache()
+{
+	local cachedir="$1"; shift
+	local name="$1"; shift
+
+	if [ -n "$cachedir" -a -n "$name" -a -d "$cachedir/$name" ];then
+		echo "$cachedir/$name"
+	else
+		echo "$etcnet_iface_dir/$name"
+	fi
+}
+
+next_iface_with_cache()
+{
+	local cachedir="$1"; shift
+	local name="$1";shift
+	local i="${1:-0}"
+	local path1="$etcnet_iface_dir/$name"
+	local path2="$cachedir/$name"
+
+	while true; do
+		if [ ! -d "$path1$i" -a ! -d "$path2$i" ] || iface_will_removed "$cachedir" "$name"; then
+			echo "$name$i"
+			break
+		fi
+		i=$(($i + 1))
+	done
+}
+
+iface_has_host_with_cache()
+{
+	local cachedir="$1"; shift
+	local name="$1"; shift
+	local i= exclude=
+
+	if [ -d "$cachedir" ]; then
+		if iface_has_host "$name" "$cachedir"; then
+			return 0
+		fi
+		# don't check in the /etc/net/ifaces ifaces which were cached
+		for i in $(find "$cachedir" -mindepth 1 -maxdepth 1 -type d 2>/dev/null); do
+			exclude="$exclude${exclude:+ -o }-path $etcnet_iface_dir/${i##*/}/options"
+		done
+		if [ -n "$exclude" ]; then
+			exclude="\( \( $exclude \) -prune -o -print \)"
+		fi
+	elif [ "$(read_iface_option "$etcnet_iface_dir/$name" TYPE)" = "vlan" ]; then
+		return 0
+	fi
+
+	for i in $(eval find "$etcnet_iface_dir" -maxdepth 2 -mindepth 2 -name options $exclude 2>/dev/null); do
+		if [ "$(read_iface_option "${i%/options}" TYPE)" = "vlan" ]; then
+			continue
+		fi
+		if egrep -qs "^HOST=[\"']?([[:alnum:]]+[[:blank:]])*$name([[:blank:]][[:alnum:]]+)*[\"']?[[:blank:]]*$" $i; then
+			return 0
+		fi
+	done
+
+	return 1
+}
+
+list_ppp_with_cache()
+{
+	local cachedir="$1"; shift
+	local t="${1:-}"
+
+	{
+		[ -d "$cachedir" ] && list_ppp "$t" "$cachedir"
+		list_ppp "$t" "$etcnet_iface_dir"
+	} | sort -u | __filter_out_removed_ifaces "$cachedir"
+}
+
+list_bond_with_cache()
+{
+	local cachedir="$1"; shift
+
+	{
+		[ -d "$cachedir" ] && list_bond "$cachedir"
+		list_bond "$etcnet_iface_dir"
+	} | sort -u | __filter_out_removed_ifaces "$cachedir"
+}
+
+# list_static_iface [ ip_version ]
+list_static_iface_with_cache()
+{
+	local cachedir="$1"; shift
+	local ipv="${1:-4}"
+
+	{
+		[ -d "$cachedir" ] && list_static_iface "$ipv" "$cachedir"
+		list_static_iface "$ipv" "$etcnet_iface_dir"
+	} | sort -u | __filter_out_removed_ifaces "$cachedir"
+}
+
 ### ipv4address calculations
 # For backward compatibility only.
 # In new code use functions from shell-ip-address directly.