#!/bin/bash

PARTITION_DIRECTORY="/dev/block/platform/msm_sdcc.1/by-name"

current_date="$(date +%Y%m%d)"

function backup_partition {
    partition_path="$1"
    partition_name="$(basename "${partition_path}")"
    echo "Backing up partition ${partition_name}."

    backup_image_name="${partition_name}-${current_date}.img"
    echo "Copying partition."
    adb shell "base64 < \"${partition_path}\"" | base64 -di > "$backup_image_name"

    echo "Hashing backup image."
    sha256sum "$backup_image_name" > "${backup_image_name}.SHA256SUM"
    backup_hash=$(cut -d ' ' -f 1 < "${backup_image_name}.SHA256SUM")

    echo "Hashing original image."
    original_hash=$(adb shell "sha256sum ${partition_path}" | cut -d ' ' -f 1)

    if [ "$original_hash" = "$backup_hash" ]; then
        echo "Backup successful."
    else
        echo "Backup of partition ${partition_name} failed."
    fi
}

# Technically this is a bit fragile, but the partition names don't break it and aren't going
# to change anytime soon and this is much easier to read than the super safe solution.
for partition_path in $(find "${PARTITION_DIRECTORY}"); do
    backup_partition "$partition_path"
done