S15resize_data

#!/bin/sh
#
# Resize the last partition to fill the SD card if it has not been already

# The number of the partition to be resized
PARTNUM=8

exec > /var/log/init.log
exec 2>&1

# If the partition is too small, resize it, and then reboot
FIRST=$(sgdisk /dev/mmcblk0 -i 8 | grep "First sector" | awk '{print $3}')
LAST=$(sgdisk /dev/mmcblk0 -i 8 | grep "Last sector" | awk '{print $3}')
SECTORS=$(expr $LAST - $FIRST)
echo "Partition is currently $SECTORS sectors"
if [[ $SECTORS -lt 2000000 ]]; then
    umount /data
    echo "Resizing partition..."
    # Get the last block of the previous partition
    PREV_END=$(sgdisk /dev/mmcblk0 -i $(expr $PARTNUM - 1) | grep "Last sector" | awk '{print $3}')
    # Sector to tart new partition on
    START=$(expr $PREV_END + 1)
    # delete existing partition
    sgdisk -d $PARTNUM /dev/mmcblk0
    # recreate, setting partition, type is 8300 (linux partition)
    sgdisk -a 1 -n $PARTNUM:$START: -c $PARTNUM:Data -t $PARTNUM:8300 /dev/mmcblk0
    sync
    echo "Rebooting..."
    reboot -f
else
    # make sure mount point exists
    mkdir -p /data
    # The filesystem has to be mounted to determine its size
    mount /dev/mmcblk0p$PARTNUM /data
    # Read the size of the filesystem
    FS_SECTORS=$(df /dev/mmcblk0p$PARTNUM | grep "/dev/mmcblk0p$PARTNUM" | awk '{print $2}')
    echo "Filesystem is $FS_SECTORS sectors"
    if [[ $FS_SECTORS -lt 1000000 ]]; then
        echo "Resizing partition"
        umount /data
        # if the filesystem is too small, recreate it
        # (it does not appear to be possible to resize an exfat fs without reformating)
        mkfs.exfat -L Data /dev/mmcblk0p$PARTNUM
        sync
    fi
fi