package/cups: Add udev rules to assign usb printers group to lp

This patch is based on patch from the rockchip tree:

commit c8a337593660f27379c30248a11bf08dc8712113
Author: Jeffy Chen <[email protected]>
Date:   Tue Nov 13 18:59:43 2018 +0800

    package: cups: Add udev rules to assign usb printers' group to lp

    Change-Id: Ieae17deaa7d3623e1f0e1cc826871f1719d98d88
    Signed-off-by: Jeffy Chen <[email protected]>

but removes a hardcoded device usb vendor/id and keps only the usb
printer class.

Signed-off-by: Angelo Compagnucci <[email protected]>
Signed-off-by: Michael Trimarchi <[email protected]>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <[email protected]>

package/cups/70-usb-printers.rules

@@ -0,0 +1,3 @@
+# Allow USB printers in the lp group
+# Match rules converted from usblp.c driver's usblp_ids
+ACTION=="add", SUBSYSTEM=="usb", ATTR{bInterfaceClass}=="07", ATTR{bInterfaceSubClass}=="01", GROUP="lp"

package/cups/cups.mk

@@ -75,6 +75,15 @@ else
 CUPS_CONF_OPTS += --disable-avahi
 endif
 
+ifeq ($(BR2_PACKAGE_HAS_UDEV),y)
+define CUPS_INSTALL_UDEV_RULES
+	$(INSTALL) -D -m 0644 package/cups/70-usb-printers.rules \
+		$(TARGET_DIR)/lib/udev/rules.d/70-usb-printers.rules
+endef
+
+CUPS_POST_INSTALL_TARGET_HOOKS += CUPS_INSTALL_UDEV_RULES
+endif
+
 define CUPS_INSTALL_INIT_SYSV
 	$(INSTALL) -D -m 0755 package/cups/S81cupsd \
 		$(TARGET_DIR)/etc/init.d/S81cupsd