bfpart

#!/bin/sh

# Copyright (c) 2017, Mellanox Technologies
# All rights reserved.
#
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# modification, are permitted provided that the following conditions are met:
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# 1. Redistributions of source code must retain the above copyright notice, this
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# Build partition on the eMMC.

set -e

usage ()
{
    echo "syntax: bfpart [-b MB] [-p MB] [-o]"
}

boot_size=350
persistent_size=250
persistent_uuid="CAFDC47B-3F21-4A78-81CC-F91944081165"

while getopts ":b:p:o" opt; do
    case $opt in
        b)
            boot_size=$OPTARG
            ;;
        p)
            persistent_size=$OPTARG
            ;;
        o)
            # overwrite persistent partition
            override_persist=1
            ;;
        \?)
            usage >&2
            exit 1
        ;;
    esac
done

start_reserved=2048    # sectors required for label before first partition
end_reserved=33        # sectors required after last partition

disk_size=$(fdisk -l /dev/mmcblk0 | grep "Disk /dev/mmcblk0:" | awk '{print $5}')
disk_size=$((disk_size / 1024 / 1024))
disk_sectors=$((disk_size * 1024 * 1024 / 512))

disk_start=$start_reserved

boot_start=$disk_start
boot_end=$((boot_size * 1024 * 1024 / 512 - 1))
boot_sectors=$((boot_end - boot_start + 1))

cur_persist_uuid="$(sfdisk --part-uuid /dev/mmcblk0 8 || true)"

if [ -z "$override_persist" ] && [ "$cur_persist_uuid" = $persistent_uuid ]; then
    # Persistent partition exists, so leave everything as we found it
    persistent_sectors="$(sfdisk -l /dev/mmcblk0 | grep '/dev/mmcblk0p8' | awk '{print $4}')"
    persistent_end="$(sfdisk -l /dev/mmcblk0 | grep '/dev/mmcblk0p8' | awk '{print $3}')"
    persistent_start="$(sfdisk -l /dev/mmcblk0 | grep '/dev/mmcblk0p8' | awk '{print $2}')"
    echo PERSIST: keep
else
    # Persistent part does not exist
    # Place persistent partition at the end of the disk
    persistent_sectors=$((persistent_size * 1024 * 1024 / 512))
    persistent_end=$((disk_sectors - end_reserved - 1))
    persistent_start=$((persistent_end - persistent_sectors + 1))
    echo PERSIST: create
fi

# Fill space between boot and persistent with root
root_start=$((boot_end + 1))
root_end=$((persistent_start - 1))
root_sectors=$((root_end - root_start + 1))

disk_end=$persistent_end

cat > /tmp/disk.sfdisk <<EOF
label: gpt
label-id: 35C59B93-2752-492B-A244-62D1BD611793
device: /dev/mmcblk0
unit: sectors
first-lba: $disk_start
last-lba: $disk_end

gpt.dat1 : start=$boot_start, size=$boot_sectors, type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, uuid=3DCADB7E-BCCC-4897-A766-3C070EDD7C25
gpt.dat2 : start=$root_start, size=$root_sectors, type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=9E61E8B5-EC9C-4299-8A0B-1B42E3DBD4AC
gpt.dat8 : start=$persistent_start, size=$persistent_sectors, type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=$persistent_uuid
EOF

dd if=/dev/zero of=/dev/mmcblk0 bs=512 count=1

sfdisk /dev/mmcblk0 < /tmp/disk.sfdisk