#!/bin/bash
exec &> >(tee -a "$0.log") 2>&1
#exec >> install.sh.log 2>&1
echo "`date`: $0 $@"

kernel_version=3.14.0

## Retrieve some Chrome OS binaries, and the dev keys for signing the kernel.
get_chromeos_files() {
        ## Mounts a rootfs to get our files from.
        sudo mkdir -p /mnt/chromeos-root
        (sudo mount -o ro /dev/sda3 /mnt/chromeos-root || sudo mount -o ro /dev/sda5 /mnt/chromeos-root) 2> /dev/null

        local files="/usr/bin/crossystem
                /usr/bin/cgpt
                /usr/bin/futility
                /usr/share/vboot/devkeys/kernel_data_key.vbprivk
                /usr/share/vboot/devkeys/kernel.keyblock"
        for file in $files; do
                cp -f /mnt/chromeos-root$file $hack/chromeos-files/
        done
}

make_kernel_image() {
        cp $hack/custom.cmdline /tmp/custom.cmdline
        echo hfd_time=`date +%F-%H_%M` >>  /tmp/custom.cmdline
        $hack/chromeos-files/futility vbutil_kernel \
          --pack $hack/.custom.kernel \
          --keyblock $hack/chromeos-files/kernel.keyblock \
          --signprivate $hack/chromeos-files/kernel_data_key.vbprivk \
          --version 1 \
          --config /tmp/custom.cmdline \
          --bootloader $hack/bootstub.efi-x86_64 \
          --vmlinuz $base/arch/x86/boot/bzImage
}

cmdline_boot() {
        ## The cmdline will point to the boot partition with parameters "root" if we are
        ## running an earlier custom kernel, or with "payload" if we are running normal
        ## Chrome Os.
        local current_root_uuid=$(cat /proc/cmdline | \
                sed 's/.* \(root\|payload\)=PARTUUID=\([0-9a-fA-F-]\+\).*/\2/')
        #log current_root_uuid: $current_root_uuid

        sudo $hack/chromeos-files/cgpt show /dev/sda | \
                grep -iB2 "$current_root_uuid" | \
                head -1 | \
                awk '{print $3}'
}

## If we booted from 2 then echo 4, from 4 then echo 2.
get_next_kern() {
        set $(sudo $hack/chromeos-files/cgpt show /dev/sda | \
                egrep ' priority=.* successful=' | \
                sed 's/.* priority=\([0-9]\+\).*/\1/'| \
                head -2)
        local kern_a_priority=$1
        local kern_b_priority=$2
        local current_kern
        if [ $kern_a_priority -gt $kern_b_priority ]; then
                current_kern=2
        else
                current_kern=4
        fi
        log current_kern: $current_kern
        assert matches_rx $current_kern '^[24]$'

        local cmdline_boot=$(cmdline_boot)
        log cmdline_boot: $cmdline_boot
        assert matches_rx $cmdline_boot '^[24]$'

        [ $cmdline_boot -eq $current_kern ] || \
                fatal "/proc/cmdline and cgpt outputs inconsistent, did I already run cgpt to set the next root? Or did a ChromeOS update download?"
        echo $current_kern | tr 24 42
}

## Writes kernel to target partition.
install_kernel() {
        local part=$1
        assert matches_rx $part '^[24]$'
        assert [ -f $base/hack/.custom.kernel ]
        $dry_run sudo dd if=$base/hack/.custom.kernel of=/dev/sda$part
}

## Installs modules to /lib/modules in the chroot.
install_modules() {
        assert [ -d $base/mod-inst/lib/modules ]
        assert [ -d /lib/modules/$kernel_version ]
        local backup=/lib/modules/$kernel_version-$(date +%F-%H_%M)
        $dry_run cp -r /lib/modules/$kernel_version $backup
        $dry_run sudo rm -rf /lib/modules/$kernel_version
        $dry_run sudo cp -r $base/mod-inst/lib/modules/$kernel_version /lib/modules/$kernel_version
}

## Make sure our kernel is run at next boot.
prioritise_kernel() {
        assert matches_rx $1 '^[24]$'
        $dry_run sudo $hack/chromeos-files/cgpt add -i $1 -S 0 -T 1 -P 15 /dev/sda
}
#install_modules_to_rootfs() {
        #assert matches_rx $1 '^[35]$'
        #assert [ -d $base/mod-inst/lib/modules ]
        #sudo mkdir -p /mnt/alt-root
        #$dry_run sudo mount /dev/sda$1 /mnt/alt-root
        #$dry_run sudo rm -rf /mnt/alt-root/lib/modules/*
        #$dry_run sudo cp -r $base/mod-inst/lib/modules /mnt/alt-root/lib/modules/
        #$dry_run sudo umount /mnt/alt-root
#}

main() {
        get_chromeos_files
        make_kernel_image
        local next_kern=$(get_next_kern)
        log "next_kern: $next_kern"
        if [ ! -z $next_kern ]; then
                log "Enter to install, Ctrl-C to cancel..."; read
                install_kernel $next_kern
                prioritise_kernel $next_kern
                install_modules
        fi
}

####
set -e
base=$(readlink -f $(dirname $0)/..)
hack=$base/hack
. $hack/functions.sh

if [ "x$1" = x-f ]; then
        shift
else
        log "dry-run mode, for applying changes run: $0 -f $@"
        dry_run=echo
fi

trap "(sudo umount /mnt/chromeos-root; sudo rmdir /mnt/chromeos-root) 2> /dev/null; exit" SIGHUP SIGINT SIGTERM EXIT
main