mknet.sh

#!/bin/sh
#
#-
# Copyright (c) 2009-2015 Juan Romero Pardines.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#-

readonly PROGNAME=$(basename "$0")
readonly REQTOOLS="xbps-install tar"

# This script needs to jump around, so we'll remember where we started
# so that we can get back here
readonly CURDIR="$(pwd)"

# This source pulls in all the functions from lib.sh.  This set of
# functions makes it much easier to work with chroots and abstracts
# away all the problems with running binaries with QEMU.
# shellcheck source=./lib.sh
. ./lib.sh

# Die is a function provided in lib.sh which handles the cleanup of
# the mounts and removal of temporary directories if the running
# program exists unexpectedly.
trap 'bailout' INT TERM

bailout() {
    [ -d "$BOOT_DIR" ] && rm -rf "$BOOT_DIR"
    die "An unchecked exception has occured!"
}

usage() {
	cat <<-EOH
	Usage: $PROGNAME [options] <rootfs-tarball>

	Generates a network-bootable tarball from a Void Linux ROOTFS generated by mkrootfs.

	OPTIONS
	 -r <repo>          Use this XBPS repository. May be specified multiple times
	 -c <cachedir>      Use this XBPS cache directory (default: )
	 -i <lz4|gzip|bzip2|xz>
	                    Compression type for the initramfs image (default: xz)
	 -o <file>          Output file name for the netboot tarball (default: automatic)
	 -K linux<version>  Install a custom Linux version on ISO image (default: linux metapackage)
	 -k <keymap>        Default keymap to use (default: us)
	 -l <locale>        Default locale to use (default: en_US.UTF-8)
	 -C "<arg> ..."     Add additional kernel command line arguments
	 -T <title>         Modify the bootloader title (default: Void Linux)
	 -S <image>         Set a custom splash image for the bootloader (default: data/splash.png)
	 -h                 Show this help and exit
	 -V                 Show version and exit
	EOH
}

# ########################################
#      SCRIPT EXECUTION STARTS HERE
# ########################################

while getopts "r:c:C:T:K:i:o:k:l:S:Vh" opt; do
    case $opt in
        r) XBPS_REPOSITORY="--repository=$OPTARG $XBPS_REPOSITORY";;
        c) XBPS_CACHEDIR="--cachedir=$OPTARG";;
        i) INITRAMFS_COMPRESSION="$OPTARG";;
        K) KERNELPKG="$OPTARG";;
        o) OUTPUT_FILE="$OPTARG";;
        k) KEYMAP="$OPTARG";;
        l) LOCALE="$OPTARG";;
        C) BOOT_CMDLINE="$OPTARG";;
        T) BOOT_TITLE="$OPTARG";;
        S) SPLASH_IMAGE="$OPTARG";;
        V) version; exit 0;;
        h) usage; exit 0;;
        *) usage >&2; exit 1;;
    esac
done
shift $((OPTIND - 1))

BASE_TARBALL="$1"

# We need to infer the target architecture from the filename.  All
# other scripts are able to get this from the platforms map because a
# platform is manually specified.  Since the netboot tarballs target
# only architectures, its necessary to pull this information from the
# filename.
XBPS_TARGET_ARCH=${BASE_TARBALL%%-ROOTFS*}
XBPS_TARGET_ARCH=${XBPS_TARGET_ARCH##void-}

# Knowing the target arch, we can set the cache up if it hasn't
# already been set
set_cachedir

# This is an aweful hack since the script isn't using privesc
# mechanisms selectively.  This is a TODO item.
if [ "$(id -u)" -ne 0 ]; then
    die "need root perms to continue, exiting."
fi

# Before going any further, check that the tools that are needed are
# present.  If we delayed this we could check for the QEMU binary, but
# its a reasonable tradeoff to just bail out now.
check_tools

# We need to operate on a tempdir, if this fails to create, it is
# absolutely crucial to bail out so that we don't hose the system that
# is running the script.
ROOTFS=$(mktemp -d) || die "failed to create ROOTFS tempdir, exiting..."
BOOT_DIR=$(mktemp -d) || die "failed to create BOOT_DIR tempdir, exiting..."
PXELINUX_DIR="$BOOT_DIR/pxelinux.cfg"

# Now that we have a directory for the ROOTFS, we can expand the
# existing base filesystem into the directory
info_msg "Expanding base tarball $BASE_TARBALL into $ROOTFS for $PLATFORM build."
tar xf "$BASE_TARBALL" -C "$ROOTFS"

info_msg "Install additional dracut modules"
# This section sets up the dracut modules that need to be present on
# the ROOTFS to build the PXE tarball.  This includes the netmenu
# module and the autoinstaller
mkdir -p "$ROOTFS/usr/lib/dracut/modules.d/05netmenu"
cp dracut/netmenu/* "$ROOTFS/usr/lib/dracut/modules.d/05netmenu/"

# The netmenu can directly launch the manual installer from the
# initrd.  This is the same installer that's on the live media with
# all its quirks, oddities, and wierdness.  It's included here for
# places where you might have a lab network and need to run manual
# installs from the network.
cp installer.sh "$ROOTFS/usr/lib/dracut/modules.d/05netmenu/"

# Of course with a PXE environment unattended installs are the norm.
# The autoinstaller is loaded as a very high priority dracut module
# and will fail the build if it can't be installed.
mkdir -p "$ROOTFS/usr/lib/dracut/modules.d/01autoinstaller"
cp dracut/autoinstaller/* "$ROOTFS/usr/lib/dracut/modules.d/01autoinstaller/"

info_msg "Install kernel and additional required netboot packages"
# The rootfs has no kernel in it, so it needs to have at the very
# least dracut, syslinux, and linux installed.  binutils provides
# /usr/bin/strip which lets us shrink down the size of the initrd
# dracut-network provides the in-initrd network stack dialog is needed
# by the install environment.  ${INITRAMFS_COMPRESSION} is the name of
# the compressor we want to use (lz4 by default).
if [ -z "${XBPS_TARGET_ARCH##*86*}" ] ; then
    # This platform is x86 or compatible, we should use
    # syslinux/pxelinux to boot the system.
    info_msg "Selecting syslinux bootloader"
    bootloader_pkg=syslinux
else
    # This is likely an arm platform of some kind.  In general these
    # either have u-boot or a u-boot compatible loader, so we'll use
    # that to produce a uImage and a uInitrd
    info_msg "Selecting u-boot bootloader"
    bootloader_pkg=uboot-mkimage
fi
run_cmd_target "xbps-install $XBPS_CONFFILE $XBPS_CACHEDIR $XBPS_REPOSITORY -r $ROOTFS -Sy ${KERNELPKG-linux} dracut binutils dracut-network dialog ${INITRAMFS_COMPRESSION-xz} ${bootloader_pkg}"
run_cmd_chroot "$ROOTFS" "xbps-reconfigure -a"

# Dracut needs to know the kernel version that will be using this
# initrd so that it can install the kernel drivers in it.  Normally
# this check is quite complex, but since this is a clean rootfs and we
# just installed exactly one kernel, this check can get by with a
# really naive command to figure out the kernel version
KERNELVERSION=$(ls "$ROOTFS/usr/lib/modules/")

# Now that things are setup, we can call dracut and build the initrd.
# This will pretty much step through the normal process to build
# initrd with the exception that the autoinstaller and netmenu are
# force added since no module depends on them.
info_msg "Building initrd for kernel version $KERNELVERSION"
run_cmd_chroot "$ROOTFS" "env -i /usr/bin/dracut \
               -N \
               --${INITRAMFS_COMPRESSION-xz} \
               --add-drivers ahci \
               --force-add 'autoinstaller netmenu' \
               --omit systemd \
               /boot/initrd \
               $KERNELVERSION"
[ $? -ne 0 ] && die "Failed to generate the initramfs"

info_msg "Collect netboot components"
if [ ${bootloader_pkg} = "syslinux" ] ; then
    # The whole point of this endeavor is to get the files needed for PXE.
    # Now that they have been generated, we copy them out of the doomed
    # ROOTFS and into the $BOOT_DIR where we're staging the rest of the
    # tarball
    mv -v "$ROOTFS/boot/initrd" "$BOOT_DIR"
    cp -v "$ROOTFS/boot/vmlinuz-$KERNELVERSION" "$BOOT_DIR/vmlinuz"

    # The initrd has *very* restrictive permissions by default.  To
    # prevent some SysAdmin down the road having a very frustrating time
    # debugging this, we just fix this here and now.
    chmod 0644 "$BOOT_DIR/initrd"

    # Now we need to grab the rest of the files that go in the tarball.
    # Some of these are always required, some of these are canonical, and
    # some of this list is from trial and error.  Either way, this is the
    # minimum needed to get Void up and booting on metal from the network.
    for prog in pxelinux.0 ldlinux.c32 libcom32.c32 vesamenu.c32 libutil.c32 chain.c32 ; do
        cp -v "$ROOTFS/usr/lib/syslinux/$prog" "$BOOT_DIR"
    done

    # Lastly we need the default pxelinux config and the splash image.
    # This is user configurable, but if that isn't set then we'll use the
    # one from data/splash.png instead
    mkdir -p "$PXELINUX_DIR"
    cp -f pxelinux.cfg/pxelinux.cfg.in "$PXELINUX_DIR/default"
    cp -f "${SPLASH_IMAGE-data/splash.png}" "$BOOT_DIR"

    # This sets all the variables in the default config file
    info_msg "Configuring pxelinux.0 default boot menu"
    sed -i  -e "s|@@SPLASHIMAGE@@|$(basename "${SPLASH_IMAGE-splash.png}")|" \
        -e "s|@@KERNVER@@|${KERNELVERSION}|" \
        -e "s|@@KEYMAP@@|${KEYMAP-us}|" \
        -e "s|@@ARCH@@|$XBPS_TARGET_ARCH|" \
        -e "s|@@LOCALE@@|${LOCALE-en_US.UTF-8}|" \
        -e "s|@@BOOT_TITLE@@|${BOOT_TITLE-Void Linux}|" \
        -e "s|@@BOOT_CMDLINE@@|${BOOT_CMDLINE}|" \
        "$PXELINUX_DIR/default"
else
    # u-boot has far far fewer components, but u-boot artifacts do
    # require some pre-processing

    if [ ! -f "$ROOTFS/boot/uImage" ] ; then

        # Build the uImage, this is really just the kernel with a wrapper
        # to make u-boot happy.  It also sets the load and entry
        # addresses, though in general these are overriden by the u-boot
        # configuration.
        run_cmd_chroot "$ROOTFS" "env -i /usr/bin/mkimage -A arm -O linux -T kernel -C none -a 0x00000000 -e 0x00000000 -n 'Void Kernel' -d /boot/zImage /boot/uImage"

        # Build the uInitrd which is similarly just a copy of the real
        # initrd in a format that u-boot is willing to ingest.
        run_cmd_chroot "$ROOTFS" "env -i /usr/bin/mkimage -A arm -O linux -T ramdisk -C none -a 0 -e 0 -n 'Void Installer Initrd' -d /boot/initrd /boot/uInitrd"

        # Copy out the artifacts that are worth keeping
        cp "$ROOTFS/boot/uImage" "$BOOT_DIR"
        cp "$ROOTFS/boot/uInitrd" "$BOOT_DIR"
        cp -r "$ROOTFS/boot/dtbs" "$BOOT_DIR"
    else
        # Copy the existing uImage out
        cp "$ROOTFS/boot/uImage" "$BOOT_DIR"
    fi
fi

# Compress the artifacts for distribution
OUTPUT_FILE="void-${XBPS_TARGET_ARCH}-NETBOOT-$(date -u +%Y%m%d).tar.gz"
info_msg "Compressing results to $OUTPUT_FILE"
cd "$BOOT_DIR" || die "Could not enter image dir"
tar -zcvf "$CURDIR/$OUTPUT_FILE" .
cd "$CURDIR" || die "Could not return to working directory"

# As a final cleanup step, remove the ROOTFS and the expanded BOOT_DIR
info_msg "Cleaning up and removing build directories"
cleanup_chroot
[ -d "$ROOTFS" ] && rm -rf "$ROOTFS"
[ -d "$BOOT_DIR" ] && rm -rf "$BOOT_DIR"