enter-qemu-chroot

#!/bin/bash

#
# Author: Keith Kyzivat <keith.kyzivat@l3-com.com>
#
# Script to prep and enter an armhf 14.04 Ubuntu Core chroot

scriptpath=`dirname $0`
scriptpath=`(cd "$scriptpath"; /bin/pwd)`

mountdirs=();
function bindmount ()
{
    src=$1
    dest=$2
    sudo mount $src $dest -o bind;
    mountdirs+=("$dest")
}

CHROOT_DIR="$1"
if [ ! -d "$CHROOT_DIR" ]; then
    CHROOT_DIR="$scriptpath/ubuntu-core-14.04.3-core-armhf-forqemu"
else
    # Shift off the chroot dir parameter.
    shift
fi

if [ ! -e "$CHROOT_DIR/etc" ]; then
    echo >&2 "Invalid chroot dir \"$CHROOT_DIR\" specified."
    echo >&2 "Aborting."
    exit 1
fi

if [ ! -e "/usr/bin/qemu-arm-static" ]; then
    echo >&2 "Qemu tools need to be installed to run arm chroot. Please run:"
    echo >&2 "  $ sudo apt-get install qemu-user-static"
    echo >&2 "Aborting."
    exit 1
fi

sudo -v

cd "$CHROOT_DIR"
if [ ! -x usr/bin/qemu-arm-static ]; then
    sudo cp -a /usr/bin/qemu-arm-static usr/bin
fi

for m in `echo 'run sys dev proc dev/pts'`; do 
    mount | grep "$CHROOT_DIR/$m" > /dev/null 2>&1
    if [ $? -gt 0 ]; then
            echo "Bind mounting /$m to $CHROOT_DIR/$m"
            bindmount /$m $CHROOT_DIR/$m
    fi
done

if [ -e /vagrant ]; then
    mount | grep "$CHROOT_DIR/vagrant" > /dev/null 2>&1
    if [ $? -gt 0 ]; then
        sudo mkdir -p $CHROOT_DIR/vagrant
        bindmount /vagrant $CHROOT_DIR/vagrant
    fi
fi

# Fix resolv.conf
if [ ! -L etc/resolv.conf ]; then
    sudo rm etc/resolv.conf
    sudo ln -s /run/resolvconf/resolv.conf etc/resolv.conf
fi

# Make sudo passwordless in chroot
if [ ! -e etc/sudoers.d/passwordless ]; then
    sudo bash -c 'echo "vagrant ALL=(ALL) NOPASSWD:ALL" >> etc/sudoers.d/passwordless'
fi

if [ ! -d "$CHROOT_DIR/home/$USER" ]; then
    echo "User account $USER doesn't exist. Creating it."
    LC_ALL=C sudo -E chroot . /usr/sbin/groupadd --gid $(id -g) $USER
    LC_ALL=C sudo -E chroot . /usr/sbin/useradd -m --uid $(id -u) --gid $(id -g) --shell $SHELL $USER
fi

if [ -d "/home/$USER/builds" ]; then
    echo "Mounting $USER's build directory in sysroot"
    mount | grep "$CHROOT_DIR/home/$USER/builds" > /dev/null 2>&1
    if [ $? -gt 0 ]; then
        bindmount $HOME/builds $CHROOT_DIR/home/$USER/builds
    fi
fi

# CAVEAT - this assumes that $USER has the uid 1000 and default group 1000
# This is the case if this is an Ubuntu (14.04 at least) machine and
# the user logged in is the first created user account on the machine.
if [ $# -gt 0 ]; then
    LC_ALL=C sudo -E chroot --userspec=1000:1000 . /bin/bash -c "$*"
else
    LC_ALL=C sudo -E chroot --userspec=1000:1000 . /bin/bash
fi

# Now, unmount all the mounted things.  Weird {{''}} syntax is to get
# around Jinja considering curley-bracket-hash a comment character -
# and ansible templates are interpreted by jinja.
for (( idx={{'${#mountdirs[@]}-1'}} ; idx>=0 ; idx-- )) ; do
    m=${mountdirs[idx]}
    echo "Unmounting $m"
    sudo umount $m
done