Add attach commands for losetup

bin/losetup-mount

@@ -0,0 +1,36 @@
+#!/bin/bash
+# readies a VHD device in Linux
+# nbd-mount /path/to/vhd /dev/nbd0
+APP_DIR="$(dirname "$0")"
+DRIVE="$1"
+DISK_LABEL="$2"
+DISK_PATH="/dev/disk/by-label/$DISK_LABEL"
+SLEEP_INTERVAL=0.5
+
+# refuse to connect twice
+EXISTING_DRIVE="$(losetup -l | tail -n +2 | tr -s ' ' | cut -f 6 | grep -w "$DRIVE")"
+if [ -n "$EXISTING_DRIVE" ]; then
+	EXISTING_LOOP="$(losetup -l | tail -n +2 | tr -s ' ' | grep -w "$DRIVE" | cut -f 1 -d ' ')"
+	if ! [ -L "$DISK_PATH" ] || ! [ -b "$DISK_PATH" ]; then
+		echo "$DRIVE already mounted to $EXISTING_LOOP"
+		exit 1
+	fi
+	LOOP_DEST="$(readlink -f $DISK_PATH)"
+	if [ "$LOOP_DEST" != "$EXISTING_LOOP" ]; then
+		echo "$DRIVE already mounted to $EXISTING_LOOP"
+		exit 1
+	fi
+
+	# it's already mounted to the same destination
+	exit 0
+fi
+
+# wait for device to appear
+if ! [ -e "$DISK_PATH" ]; then
+	losetup -f "$DRIVE"
+
+	# poll until the block device node appears or task times out
+	until [ -L "$DISK_PATH" ] && [ -b "$DISK_PATH" ]; do
+		sleep "$SLEEP_INTERVAL"
+	done
+fi

bin/losetup-unmount

@@ -0,0 +1,30 @@
+#!/bin/bash
+# disconnects a VHD device from linux (should be unmounted)
+# nbd-unmount path-to-vhd
+DRIVE="$1"
+
+if [ -z "$DRIVE" ]; then
+	echo "Drive not provided"
+	exit 1
+fi
+
+if ! [ -f "$DRIVE" ]; then
+	echo "$DRIVE not existing"
+	exit 1
+fi
+
+EXISTING_DRIVE="$(losetup -l | tail -n +2 | tr -s ' ' | cut -f 6 | grep -w "$DRIVE")"
+if [ -z "$EXISTING_DRIVE" ]; then
+	echo "$DRIVE not mounted"
+	exit 1
+fi
+
+EXISTING_LOOP="$(losetup -l | tail -n +2 | tr -s ' ' | grep -w "$DRIVE" | cut -f 1 -d ' ')"
+LOOP_DEST="$(readlink -f $EXISTING_LOOP)"
+
+if mount | grep ^"$LOOP_DEST" -q ; then
+	echo "$LOOP_DEST mounted, refusing to detach"
+	exit 1
+fi
+
+losetup -d "$LOOP_DEST"

bin/nbd-find-free

@@ -0,0 +1,17 @@
+#!/bin/bash
+# returns an unused nbd device
+for sys_path in /sys/block/nbd[0-9]*; do
+	[ -d "$sys_path" ] || continue
+
+	if [ -f "$sys_path/size" ] && [ "$(< "$sys_path/size")" -eq 0 ] ; then
+		TARGET="/dev/${sys_path##*/}"
+		break
+	fi
+done
+
+if [ -z "$TARGET" ]; then
+	echo "Error: no free NBD device found" >&2
+	exit 1
+fi
+
+echo $TARGET

bin/nbd-mount

@@ -0,0 +1,39 @@
+#!/bin/bash
+# readies a VHD device in Linux
+# nbd-mount /path/to/vhd /dev/nbd0
+APP_DIR="$(dirname "$0")"
+NBD_FIND_FREE="$APP_DIR/nbd-find-free"
+DRIVE="$1"
+DISK_LABEL="$2"
+DISK_PATH="/dev/disk/by-label/$DISK_LABEL"
+SLEEP_INTERVAL=0.5
+
+# find an empty nbd device
+NBD_TARGET="$($NBD_FIND_FREE)"
+if [ -z "$NBD_TARGET" ]; then
+	echo "Cannot find free nbd device"
+	exit 1
+fi
+
+# refuse to connect twice
+EXISTING_DRIVE=$(pgrep -f "qemu-nbd.*$DRIVE")
+if [ -n "$EXISTING_DRIVE" ]; then
+	echo "$DRIVE already mounted" >&2
+	exit 1
+fi
+EXISTING_NBD="$(pgrep -f "qemu-nbd.*$NBD_TARGET")"
+if [ -n "$EXISTING_NBD" ]; then
+	echo "$NBD_TARGET already mounted" >&2
+	exit 1
+fi
+
+
+# wait for device to appear
+if ! [ -e "$DISK_PATH" ]; then
+	qemu-nbd --connect="$NBD_TARGET" "$DRIVE"
+
+	# poll until the block device node appears or task times out
+	until [ -L "$DISK_PATH" ] && [ -b "$DISK_PATH" ]; do
+		sleep "$SLEEP_INTERVAL"
+	done
+fi

bin/nbd-ready

@@ -0,0 +1,6 @@
+#!/bin/bash
+# returns succesful when nbd is ready
+if [ -b /dev/nbd0 ]; then
+	exit 0
+fi
+exit 1

bin/nbd-unmount

@@ -0,0 +1,35 @@
+#!/bin/bash
+# disconnects a VHD device from linux (should be unmounted)
+# nbd-unmount path-to-vhd
+DRIVE="$1"
+QEMU_NBD_COMMAND="ps aux|grep '[q]emu-nbd.*--connect='|tr -s ' '|cut -f 11- -d ' '"
+
+if [ -z "$DRIVE" ]; then
+	echo "Drive not provided"
+	exit 1
+fi
+
+if ! [ -f "$DRIVE" ]; then
+	echo "$DRIVE not existing"
+	exit 1
+fi
+
+# iterate over all mounted nbds
+NBD_TARGET=
+while read MOUNT; do
+	if echo "$MOUNT" | egrep "$DRIVE$" > /dev/null; then
+		NBD_TARGET="$(echo "$MOUNT" | sed -E 's!.*(--connect=?|-c\s+)([^[:space:]]+).*!\2!g')"
+	fi
+done < <(eval "$QEMU_NBD_COMMAND")
+
+if [ -z "$NBD_TARGET" ]; then
+	echo "$DRIVE not mounted"
+	exit 1
+fi
+
+if mount | grep ^"$NBD_TARGET" -q ; then
+	echo "$NBD_TARGET mounted, refusing to detach"
+	exit 1
+fi
+
+qemu-nbd --disconnect=$NBD_TARGET

bin/nbd-wait

@@ -0,0 +1,17 @@
+#!/bin/bash
+# wait until nbd is ready
+APP_DIR="$(dirname "$0")"
+NBD_READY="$APP_DIR/nbd-ready"
+INTERVAL=0.5
+
+TIMEOUT=$1
+SECONDS=0
+
+until $NBD_READY; do
+	if [ "$TIMEOUT" ] && (( SECONDS >= "$TIMEOUT" )); then
+		echo "Timeout waiting for NBD" >&2
+		exit 1
+	fi
+	
+	sleep $INTERVAL
+done