[Buildroot] [RFC, PATCH 1/8] package/busybox: Add facility for DHCP hooks

[Jeremy Kerr]

The (u)dhcpc hook installed by the busybox package configures the
network and exits. If we want to do anything further with a DHCP lease,
we'd have to replace the script entirely.

This change introduces a .d directory for hooks (based on the script
filename), which are executed after the interface configuration. This
allows packages to drop a script file in the .d directory to perform
actions on DHCP events.

We'll use this in a later change to notify petitboot of DHCP boot
information.

Signed-off-by: Jeremy Kerr <jk at ozlabs.org>

---
 package/busybox/busybox.mk    |    2 ++
 package/busybox/udhcpc.script |    9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/package/busybox/busybox.mk b/package/busybox/busybox.mk
index f6f542e2..6ff5f3da 100644
--- a/package/busybox/busybox.mk
+++ b/package/busybox/busybox.mk
@@ -200,6 +200,8 @@ define BUSYBOX_INSTALL_TARGET_CMDS
 	if [ ! -f $(TARGET_DIR)/usr/share/udhcpc/default.script ]; then \
 		$(INSTALL) -m 0755 -D package/busybox/udhcpc.script \
 			$(TARGET_DIR)/usr/share/udhcpc/default.script; \
+		$(INSTALL) -m 755 -d \
+			$(TARGET_DIR)/usr/share/udhcpc/default.script.d; \
 	fi
 	$(BUSYBOX_INSTALL_MDEV_SCRIPT)
 	$(BUSYBOX_INSTALL_MDEV_CONF)
diff --git a/package/busybox/udhcpc.script b/package/busybox/udhcpc.script
index 43742fbd..8930d4a8 100755
--- a/package/busybox/udhcpc.script
+++ b/package/busybox/udhcpc.script
@@ -63,4 +63,13 @@ case "$1" in
 		;;
 esac
 
+HOOK_DIR="$0.d"
+if [ -d "$HOOK_DIR" ]
+then
+	for HOOK in $HOOK_DIR/*; do
+		$HOOK "$@"
+	done
+fi
+
+
 exit 0