changeimg

#!/bin/sh

# A tool to manipulate a VDI image. Useful for adding/removing users,
# changing passwords, setting up ssh keys, etc. without starting the VM.

# Requires 'shift', so might not work with all shells. We are interested
# in dash and bash only anyway.

set -e

OP="$1"

fatal() {
    printf %s\\n "fatal error: $@"
    exit 1
}

setup() {
    DISK="$2"
    [ ! -f "$DISK" ] && fatal "usage: $0 setup <harddisk.vdi>"
    [ ! -b /dev/nbd0 ] && fatal "/dev/nbd0 not found, maybe run modprobe nbd?"
    if [ -z "`pgrep qemu-nbd`" ]; then
        qemu-nbd -c /dev/nbd0 "$DISK" || fatal "qemu-nbd -c /dev/nbd0 failed"
    fi
    [ ! -b /dev/mapper/nbd0p1 ] && kpartx -sa /dev/nbd0
    [ ! -b /dev/mapper/nbd0p1 ] && fatal "kpartx -sa /dev/nbd0 failed"
    mkdir -p target
    if [ ! -f target/vmlinuz ]; then
        mount /dev/mapper/nbd0p1 target || fatal "mount /dev/mapper/nbd0p1 failed"
    fi
    echo Setup successful
}

cleanup() {
    if [ -f target/vmlinuz ]; then
        umount target || fatal "umount target failed"
    fi
    [ -b /dev/mapper/nbd0p1 ] && kpartx -d /dev/nbd0
    [ -b /dev/mapper/nbd0p1 ] && fatal "kpartx -d /dev/nbd0 failed"
    [ -n "`pgrep qemu-nbd`" ] && qemu-nbd -d /dev/nbd0
    [ -n "`pgrep qemu-nbd`" ] && fatal "seems like qemu-nbd still running"
    echo Cleanup successful
}

local_run() {
    SCRIPT="$2"
    [ ! -x "$SCRIPT" ] && fatal "usage: changeimg local_run <executable> <args>"
    [ ! -f target/vmlinuz ] && fatal "run setup first"

    cp "$SCRIPT" target/tmp/liox_tmp
    shift;
    exec chroot target tmp/liox_tmp "$@"
}

chroot() {
    [ ! -f target/vmlinuz ] && fatal "run setup first"
    [ -z "$2" ] && exec chroot target /bin/bash -i
    shift;
    exec chroot target "$@"
}

case $OP in
    setup )
        setup "$@"
        ;;
    local_run )
        local_run "$@"
        ;;
    chroot )
        chroot "$@"
        ;;
    cleanup )
        cleanup "$@"
        ;;
    * )
        echo "Usage: $0 (setup|local_run|chroot|cleanup)" ;;
esac