add some tooling that baremetal-devstack wants

- add bin/disk-image-get-kernel to extract vmlinuz/initrd from .qcow2
- add corresponding methods to lib/common-functions
  - map_nbd
  - (un)mount_qcow_image

bin/disk-image-get-kernel

@@ -0,0 +1,86 @@
+#!/bin/bash
+#
+# Copyright 2012 Hewlett-Packard Development Company, L.P.
+# All Rights Reserved.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+set -e
+set -o xtrace
+
+SCRIPTNAME=$(basename $0)
+export _LIB=$(dirname $0)/../lib
+source $_LIB/die
+
+function show_options () {
+    echo "Usage: $SCRIPTNAME -i <image> [-d <outdir>] [-o <prefix]"
+    echo
+    echo "Options:"
+    echo "    -i filename -- extract kernel + ramdisk from this file"
+    echo "    -d dir      -- save files in \$dir; defaults to /tmp"
+    echo "    -o prefix   -- set the prefix of the output files; defaults to 'baremetal'"
+    echo "                   eg, baremetal-vmlinuz and baremetal-initrd"
+    echo "    -x          -- turn on tracing"
+    echo "    -h          -- print this message"
+    exit 0
+}
+
+TEMP=`getopt -o hd:i:o:x -n $SCRIPTNAME -- "$@"`
+echo "XXX $TEMP"
+if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi
+
+# Note the quotes around `$TEMP': they are essential!
+eval set -- "$TEMP"
+
+export OUT_DIR=/tmp
+export OUT_PFX=baremetal
+
+while true ; do
+    case "$1" in
+        -d) export OUT_DIR=$2; shift 2 ;;
+        -i) export IMAGE_FILE=$2; shift 2 ;;
+        -o) export OUT_PFX=$2; shift 2 ;;
+        -h) show_options;;
+        -x) shift; set -x;;
+        --) shift ; break ;;
+        *) echo "Internal error!" ; exit 1 ;;
+    esac
+done
+
+if [[ ! -n "$IMAGE_FILE" ]]; then
+   die "You must specify an image to read from with -i \$filename"
+elif [[ ! -r "$IMAGE_FILE" ]]; then
+   die "Image file $IMAGE_FILE is not readable"
+fi
+
+source $_LIB/img-defaults
+source $_LIB/common-functions
+source $_LIB/img-functions
+
+echo "Extracting kernel + ramdisk from $IMAGE_FILE and writing them to $OUT_DIR"
+
+# sets WORK_DIR
+mount_qcow_image $IMAGE_FILE
+
+# Dig up the initrd and kernel to use.
+BOOTDIR="$WORK_DIR/boot"
+KERNEL=$(basename `ls -1 $BOOTDIR/vmlinuz*generic | sort -n | tail -1`)
+RAMDISK=$(basename `ls -1 $BOOTDIR/initrd*generic | sort -n | tail -1`)
+sudo cp $BOOTDIR/$KERNEL $OUT_DIR/$OUT_PFX-vmlinuz
+sudo cp $BOOTDIR/$RAMDISK $OUT_DIR/$OUT_PFX-initrd
+sudo chmod a+r $OUT_DIR/$OUT_PFX-vmlinuz
+sudo chmod a+r $OUT_DIR/$OUT_PFX-initrd
+
+unmount_qcow_image
+
+echo "$OUT_PFX-vmlinuz,$OUT_PFX-initrd"

lib/common-functions

@@ -60,3 +60,50 @@ function eval_run_d () {
       eval "$TEMP"
   fi
 }
+
+# Usage: map_nbd $image
+# Returns nbd device path
+function map_nbd {
+    (lsmod | grep '^nbd ') || sudo modprobe nbd max_part=16
+
+    if [[ $(qemu-nbd --help | grep cache) == *writeback* ]] ; then 
+        CACHE="--cache=writeback"
+    else 
+        echo "Warning: qemu-nbd without --cache=writeback is /slow/."
+        CACHE=""
+    fi
+    NBD_DEV=
+    for i in `seq 0 15`; do
+        if [ ! -e /sys/block/nbd$i/pid ]; then
+            NBD_DEV=/dev/nbd$i
+            # Connect to nbd and wait till it is ready
+            sudo qemu-nbd -c $NBD_DEV $CACHE $1
+            if ! timeout 60 sh -c "while ! [ -e /sys/block/nbd$i/pid ]; do sleep 1; done"; then
+                echo "Couldn't connect $NBD_DEV"
+                exit 1
+            fi
+            break
+        fi
+    done
+    if [ -z "$NBD_DEV" ]; then
+        echo "No free NBD slots"
+        exit 1
+    fi
+}
+
+# Delete and unmount the working dir used in extracting kernel/initrd
+function unmount_qcow_image () {
+    sudo umount $WORK_DIR || true
+    sudo qemu-nbd -d $NBD_DEV || true
+    sudo rm -rf $WORK_DIR
+
+    trap - SIGHUP SIGINT SIGTERM EXIT
+}
+
+function mount_qcow_image() {
+    trap unmount_qcow_image SIGHUP SIGINT SIGTERM EXIT
+
+    WORK_DIR=$(mktemp -d)
+    map_nbd $1
+    sudo mount $NBD_DEV $WORK_DIR
+}