#!/usr/bin/env bash

# Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# 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.
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# Neither the name of ARM nor the names of its contributors may be used
# to endorse or promote products derived from this software without specific
# prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# POSSIBILITY OF SUCH DAMAGE.

set -e

MAKE_EXT4FS=${MAKE_EXT4FS:-make_ext4fs}

IMG=${IMG:-android.img}
IMAGE_LEN=${IMAGE_LEN:-2048}

size_in_mb() {
	local size_in_bytes
	size_in_bytes=$(wc -c $1)
	size_in_bytes=${size_in_bytes%% *}
	echo $((size_in_bytes / 1024 / 1024 + 1))
}

SYSTEM_IMG=${SYSTEM_IMG:-system.img}
SYSTEM_SIZE=$(size_in_mb ${SYSTEM_IMG})
USERDATA_IMG=${USERDATA_IMG:-userdata.img}
USERDATA_SIZE=$(size_in_mb ${USERDATA_IMG})

CACHE_IMG=${CACHE_IMG:-cache.img}
CACHE_DIR=cache
CACHE_SIZE=$((IMAGE_LEN - SYSTEM_SIZE - USERDATA_SIZE - 4))
CACHE_MIN_SIZE=128
CACHE_LABEL=cache

# sanity size check
if [[ $CACHE_SIZE -le $CACHE_MIN_SIZE ]]; then
	echo "You can't fit everything into a ${IMAGE_LEN}MB image whilst having a ${CACHE_MIN_SIZE}M cache."
	exit 1
fi

# measured in MBytes
PART1_START=1
PART1_END=4
PART2_START=${PART1_END}
PART2_END=$((PART2_START + SYSTEM_SIZE))
PART3_START=${PART2_END}
PART3_END=$((PART3_START + CACHE_SIZE))
PART4_START=${PART3_END}
PART4_END=${IMAGE_LEN}

# Compute the size of the cache partition
CACHE_LEN=$((PART3_END - PART3_START))M

# We don't want parted to mess with alignment or try to be smart
PARTED="parted -a none --script"

# Create an empty disk image file
dd if=/dev/zero of=$IMG bs=1M count=$IMAGE_LEN

# Create a partition table
$PARTED $IMG unit s mktable msdos

# Create partitions
SEC_PER_MB=$((1024*2))
$PARTED $IMG unit s mkpart p fat32 $((PART1_START * SEC_PER_MB)) $((PART1_END * SEC_PER_MB - 1))
$PARTED $IMG unit s mkpart p ext4 $((PART2_START * SEC_PER_MB)) $((PART2_END * SEC_PER_MB - 1))
$PARTED $IMG unit s mkpart p ext4 $((PART3_START * SEC_PER_MB)) $((PART3_END * SEC_PER_MB - 1))
$PARTED $IMG unit s mkpart e $((PART4_START * SEC_PER_MB)) $((PART4_END * SEC_PER_MB - 1))
$PARTED $IMG unit s mkpart l ext4 $((PART4_START * SEC_PER_MB + 1)) $((PART4_END * SEC_PER_MB - 1))

# Create an ext4 partition for the cache partition
mkdir -p $CACHE_DIR
$MAKE_EXT4FS -l $CACHE_LEN -L $CACHE_LABEL $CACHE_IMG $CACHE_DIR

# Assemble all the images into one final image
dd if=$SYSTEM_IMG of=$IMG bs=1M seek=${PART2_START} conv=notrunc
dd if=$CACHE_IMG of=$IMG bs=1M seek=${PART3_START} conv=notrunc
dd if=$USERDATA_IMG of=$IMG seek=$((PART4_START * SEC_PER_MB + 1)) conv=notrunc