[OE-core] [PATCH 1/2] busybox-mdev: Support automatic mounting of block devices

[Mike Looijmans]

Upon inserting a USB stick or similar device, mdev will run
an automounter script that mounts valid partitions on
/media/<device>. The script first checks /etc/fstab entries
so that mounting on UUID or LABEL or using custom mount options
is still possible. If /etc/fstab does not contain particular
mount options, the script will create (and remove) the mountpoint
automatically.
The script also supports full disk partitions (devices without
partition table).

The automatic mounting can be disabled by adding a line
MDEV_AUTOMOUNT=y
into /etc/default/mdev

Automatic mounting for a particular device can be disabled by
creating a file "/dev/<device>.nomount". This is helpful in
scripts that create partitions for example, and want to perform
specific actions which require the device to remain unmounted.

A more complex variation (using LABEL based mounts) on this script
has been in use in OpenPLi for many years now, and I've used this
one on many projects already, so it's about time to push this to
mainline.

Signed-off-by: Mike Looijmans <mike.looijmans at topic.nl>
---
 meta/recipes-core/busybox/busybox.inc         |    1 +
 meta/recipes-core/busybox/busybox_1.22.1.bb   |    1 +
 meta/recipes-core/busybox/busybox_git.bb      |    1 +
 meta/recipes-core/busybox/files/mdev-mount.sh |   62 +++++++++++++++++++++++++
 meta/recipes-core/busybox/files/mdev.conf     |    3 ++
 5 files changed, 68 insertions(+)
 create mode 100644 meta/recipes-core/busybox/files/mdev-mount.sh

diff --git a/meta/recipes-core/busybox/busybox.inc b/meta/recipes-core/busybox/busybox.inc
index deb2ee4..0769d92 100644
--- a/meta/recipes-core/busybox/busybox.inc
+++ b/meta/recipes-core/busybox/busybox.inc
@@ -270,6 +270,7 @@ do_install () {
                        install -m 644 ${WORKDIR}/mdev.conf ${D}${sysconfdir}/mdev.conf
                        install -d ${D}${sysconfdir}/mdev
                        install -m 0755 ${WORKDIR}/find-touchscreen.sh ${D}${sysconfdir}/mdev
+                       install -m 0755 ${WORKDIR}/mdev-mount.sh ${D}${sysconfdir}/mdev
                fi
 	fi
 
diff --git a/meta/recipes-core/busybox/busybox_1.22.1.bb b/meta/recipes-core/busybox/busybox_1.22.1.bb
index 82f7f68..f379bb6 100644
--- a/meta/recipes-core/busybox/busybox_1.22.1.bb
+++ b/meta/recipes-core/busybox/busybox_1.22.1.bb
@@ -20,6 +20,7 @@ SRC_URI = "http://www.busybox.net/downloads/busybox-${PV}.tar.bz2;name=tarball \
            file://busybox-syslog.default \
            file://mdev \
            file://mdev.conf \
+           file://mdev-mount.sh \
            file://umount.busybox \
            file://defconfig \
            file://busybox-syslog.service.in \
diff --git a/meta/recipes-core/busybox/busybox_git.bb b/meta/recipes-core/busybox/busybox_git.bb
index f2cc119..f91b552 100644
--- a/meta/recipes-core/busybox/busybox_git.bb
+++ b/meta/recipes-core/busybox/busybox_git.bb
@@ -24,6 +24,7 @@ SRC_URI = "git://busybox.net/busybox.git \
            file://busybox-syslog.default \
            file://mdev \
            file://mdev.conf \
+           file://mdev-mount.sh \
            file://umount.busybox \
            file://defconfig \
            file://busybox-syslog.service.in \
diff --git a/meta/recipes-core/busybox/files/mdev-mount.sh b/meta/recipes-core/busybox/files/mdev-mount.sh
new file mode 100644
index 0000000..60ecf88
--- /dev/null
+++ b/meta/recipes-core/busybox/files/mdev-mount.sh
@@ -0,0 +1,62 @@
+#!/bin/sh
+MDEV_AUTOMOUNT=y
+[ -f /etc/default/mdev ] && . /etc/default/mdev
+if [ "${MDEV_AUTOMOUNT}" = "n" ] ; then
+	exit 0
+fi
+
+case "$ACTION" in
+	add|"")
+		ACTION="add"
+		# check if already mounted
+		if grep -q "^/dev/${MDEV} " /proc/mounts ; then
+			# Already mounted
+			exit 0
+		fi
+		DEVBASE=`expr substr $MDEV 1 3`
+		if [ "${DEVBASE}" == "mmc" ] ; then
+			DEVBASE=`expr substr $MDEV 1 7`
+		fi
+		# check for "please don't mount it" file
+		if [ -f "/dev/nomount.${DEVBASE}" ] ; then
+			# blocked
+			exit 0
+		fi
+		# check for full-disk partition
+		if [ "${DEVBASE}" == "${MDEV}" ] ; then
+			if [ -d /sys/block/${DEVBASE}/${DEVBASE}*1 ] ; then
+				# Partition detected, just quit
+				exit 0
+			fi
+			if [ ! -f /sys/block/${DEVBASE}/size ] ; then
+				# No size at all
+				exit 0
+			fi
+			if [ `cat /sys/block/${DEVBASE}/size` == 0 ] ; then
+				# empty device, bail out
+				exit 0
+			fi
+		fi
+		# first allow fstab to determine the mountpoint
+		if ! mount /dev/$MDEV > /dev/null 2>&1
+		then
+			MOUNTPOINT="/media/$MDEV"
+			mkdir "$MOUNTPOINT"
+			mount -t auto /dev/$MDEV "$MOUNTPOINT"
+		fi
+		;;
+	remove)
+		MOUNTPOINT=`grep "^/dev/$MDEV\s" /proc/mounts | cut -d' ' -f 2`
+		if [ ! -z "$MOUNTPOINT" ]
+		then
+			umount "$MOUNTPOINT"
+			rmdir "$MOUNTPOINT"
+		else
+			umount /dev/$MDEV
+		fi
+		;;
+	*)
+		# Unexpected keyword
+		exit 1
+		;;
+esac
diff --git a/meta/recipes-core/busybox/files/mdev.conf b/meta/recipes-core/busybox/files/mdev.conf
index e688911..c83bb4c 100644
--- a/meta/recipes-core/busybox/files/mdev.conf
+++ b/meta/recipes-core/busybox/files/mdev.conf
@@ -35,3 +35,6 @@ input/mice 0:0 0660
 input/mouse.* 0:0 0660
 
 tun[0-9]* 0:0 0660 =net/
+
+[hs]d[a-z][0-9]? 0:0 660 */etc/mdev/mdev-mount.sh
+mmcblk[0-9].* 0:0 660 */etc/mdev/mdev-mount.sh
-- 
1.7.9.5