Gentoo-Prefix chroot for Chrome OS

0 Gentoo-Prefix chroot for Chrome OS

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prep-gentoo.sh

#!/usr/bin/env bash

user=$(id -run)
group=$(id -grn)
dir=/usr/local/${user}
forcerel=${1:-""}

assert_base_dir() {
    [ -d ${dir} ] || sudo mkdir -pv ${dir}
    sudo chown --from=root ${user}:${group} ${dir}
}

assert_bind_mount() {
    local mount="${1}"
    local mountpoint="${dir}/gentoo${mount}"
    check_mount ${mount} || do_mount ${mount} ${mountpoint}
}

assert_bind_mounts() {
    assert_bind_mount /dev
    assert_bind_mount /tmp/gentoo
    assert_bind_mount /proc
    assert_bind_mount /sys
    assert_bind_mount $HOME
    assert_bind_mount /etc/resolv.conf
    assert_bind_mount /etc/passwd
    assert_bind_mount /etc/group
    assert_bind_mount /etc/hosts
}

assert_chroot_prep() {
    sudo mkdir -pv ${dir}/gentoo/dev
    sudo mkdir -pv ${dir}/gentoo/tmp/gentoo
    sudo mkdir -pv ${dir}/gentoo/proc
    sudo mkdir -pv ${dir}/gentoo${HOME}
    sudo mkdir -pv ${dir}/gentoo/sys
    if [ -L ${dir}/gentoo/dev ]; then
        echo "${dir}/gentoo/dev cannot be a symlink"
        exit 1
    fi
    if [ -L ${dir}/gentoo/tmp/gentoo ]; then
        echo "${dir}/gentoo/tmp/gentoo cannot be a symlink"
        exit 1
    fi
    if [ -L ${dir}/gentoo/proc ]; then
        echo "${dir}/gentoo/proc cannot be a symlink"
        exit 1
    fi
    if [ -L ${dir}/gentoo/sys ]; then
        echo "${dir}/gentoo/sys cannot be a symlink"
        exit 1
    fi

    assert_bind_mounts
}

assert_distribution() {
    [ -d $dir/gentoo ] || extract_remote_release
}

assert_tmp_link() {
    ln -sf ${dir}/gentoo /tmp/gentoo || sudo ln -sf ${dir}/gentoo /tmp/gentoo

    # And make sure it is relinked when we run the shell again (after reboot)
    assert_tmp_link_in_bashrc
}

assert_tmp_link_in_bashrc() {
    grep "ln .*${dir}/gentoo" ~/.bashrc >/dev/zero || echo "ln -sf ${dir}/gentoo /tmp/gentoo" >> ~/.bashrc
}

check_mount() {
    local mount="${1}"
    [ ! -e ${mount} ] && true || grep "${dir}/gentoo" /proc/mounts | awk '{ print $2 }' | grep "^${dir}/gentoo${mount}$" >/dev/zero
}

display_chroot_help() {
    echo " "
    echo "Run the following command to enter the prefix at ${dir}/gentoo within a chroot:"
    echo "    sudo -E chroot --userspec=${user}:${group} ${dir}/gentoo '/startprefix_original'"
    echo " "
}

do_mount() {
    local mount="${1}"
    local mountpoint="${2}"
    if [ "x" != "x${mount}" -a "x" != "x${mountpoint}" ]; then
        echo "Mounting ${mount} at ${mountpoint}"
        if [ -f ${mount} ]; then
            sudo cp -fv ${mount} ${mountpoint}
        else
            sudo mount --bind "${mount}" "${mountpoint}"
        fi
    fi
}

extract_remote_release() {
    if [ -L ${dir} ]; then
        echo "${dir} should not be a symlink"
        exit 1
    fi
    local release="https://github.com$(curl -sL https://github.com/awesomebytes/gentoo_prefix_ci/releases/latest | grep -E 'href=".*?/archive/.*?\.tar\.gz"' | sed -e 's;.*href="\(.*\)" rel.*;\1;')"
    release=${forcerel:-release}

    if [ "${release}" > "http" -a "${release}" < "httq" ]; then
        curl -sL "${release}" | tar --directory=${dir} -zxv
    else
        tar --directory=${dir} -zxvf ${release}
    fi
}

# Ensure we're not in a chroot
if [ ! -d /mnt/stateful_partition ]; then
    exit 0;
fi

# Get the release
assert_base_dir
assert_distribution
assert_tmp_link

# Convenience link in $HOME
[ -e ~/gentoo ] || ln -sf ${dir}/gentoo ~/gentoo

assert_chroot_prep
display_chroot_help