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#!/bin/sh
type getarg > /dev/null 2>&1 || . /lib/dracut-lib.sh
if getargbool 0 rd.live.debug -n -y rdlivedebug; then
exec > /tmp/create-overlay.$$.out
exec 2>> /tmp/create-overlay.$$.out
set -x
fi
gatherData() {
overlay=$(getarg rd.live.overlay)
if [ -z "$overlay" ]; then
info "Skipping overlay creation: kernel command line parameter 'rd.live.overlay' is not set"
exit 0
fi
if ! str_starts "${overlay}" LABEL=; then
die "Overlay creation failed: the partition must be set by LABEL in the 'rd.live.overlay' kernel parameter"
fi
overlayLabel=${overlay#LABEL=}
if [ -b "/dev/disk/by-label/${overlayLabel}" ]; then
info "Skipping overlay creation: overlay already exists"
exit 0
fi
filesystem=$(getarg rd.live.overlay.cowfs)
[ -z "$filesystem" ] && filesystem="ext4"
if [ "$filesystem" != "ext4" ] && [ "$filesystem" != "xfs" ] && [ "$filesystem" != "btrfs" ]; then
die "Overlay creation failed: only ext4, xfs, and btrfs are supported in the 'rd.live.overlay.cowfs' kernel parameter"
fi
live_dir=$(getarg rd.live.dir)
[ -z "$live_dir" ] && live_dir="LiveOS"
[ -z "$1" ] && exit 1
rootDevice=$1
# The kernel command line's 'root=' parameter was parsed into the $root variable by the dmsquash-live module.
# $root contains the path to a symlink within /dev/disk/by-label, which points to a partition.
# This script needs that partition's parent block device.
rootDeviceAbsolutePath=$(readlink -f "${rootDevice}")
rootDeviceSysfsPath="/sys/class/block/${rootDeviceAbsolutePath##*/}"
if [ -f "${rootDeviceSysfsPath}/partition" ]; then
read -r partition < "${rootDeviceSysfsPath}/partition"
else
partition=0
fi
read -r readonly < "${rootDeviceSysfsPath}/ro"
if [ "$partition" != "1" ] || [ "$readonly" != "0" ]; then
info "Skipping overlay creation: unpartitioned or read-only media detected"
exit 0
fi
fullDriveSysfsPath=$(readlink -f "${rootDeviceSysfsPath}/..")
blockDevice="/dev/${fullDriveSysfsPath##*/}"
currentPartitionCount=$(grep --count -E "${blockDevice#/dev/}[0-9]+" /proc/partitions)
freeSpaceStart=$(parted --script "${blockDevice}" unit % print free \
| awk -v "x=${currentPartitionCount}" '$1 == x {getline; print $1}')
if [ -z "$freeSpaceStart" ]; then
info "Skipping overlay creation: there is no free space after the last partition"
exit 0
fi
partitionStart=$((${freeSpaceStart%.*} + 1))
if [ $partitionStart -eq 100 ]; then
info "Skipping overlay creation: there is not enough free space after the last partition"
exit 0
fi
overlayPartition=${blockDevice}$((currentPartitionCount + 1))
label=$(blkid --match-tag LABEL --output value "$rootDevice")
uuid=$(blkid --match-tag UUID --output value "$rootDevice")
if [ -z "$label" ] || [ -z "$uuid" ]; then
die "Overlay creation failed: failed to look up root device label and UUID"
fi
}
createPartition() {
parted --script --align optimal "${blockDevice}" mkpart primary ${partitionStart}% 100%
}
createFilesystem() {
"mkfs.${filesystem}" -L "${overlayLabel}" "${overlayPartition}"
baseDir=/run/initramfs/create-overlayfs
mkdir -p ${baseDir}
mount -t "${filesystem}" "${overlayPartition}" ${baseDir}
mkdir -p "${baseDir}/${live_dir}/ovlwork"
mkdir "${baseDir}/${live_dir}/overlay-${label}-${uuid}"
umount ${baseDir}
rm -r ${baseDir}
}
main() {
gatherData "$1"
createPartition
udevsettle
createFilesystem
udevsettle
}
main "$1"
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