#!/bin/sh

#############################################################
# Author: Taryel Hlontsi, 2024
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>
#############################################################

doc=$(cat <<'EOF'
NOTES:
To be able to mount a directory in NetBSD that runs as KVM/Qemu quest
the following has to be done:
1) the kernel must include vio9p driver (not included by default)
2) dev node has to be created for the character device (file share in this case)
3) mount_9p utility must be used to mount the file share
4) (oprional) a service can be created that mounts the fileshare at boot time
EOF
)


#############################################################
#          HELPER FUNCTIONS
#############################################################

info() {
    GREEN='\033[1;32m'
    NC='\033[0m'
    echo -e "${GREEN}$1${NC}"
}

trace() {
    YELLOW='\033[1;33m'
    NC='\033[0m'
    echo -e "${YELLOW}$1${NC}"
}

warn() {
    PURPLE='\033[1;35m'
    NC='\033[0m'
    echo -e "${PURPLE}$1${NC}"
}

error() {
    RED='\033[1;31m'
    NC='\033[0m'
    echo -e "${RED}$1${NC}"
}


#############################################################
#          1 - BUILD AND INSTALL KERNEL THAT SUPPORTS VIO9P DRIVER
#############################################################
install_kernel_with_vio9p() {
    local step_name='STEP 1: BUILD AND INSTALL KERNEL THAT SUPPORTS VIO9P'
    warn "Press enter to proceed with $step_name"; read confirm
    info "$step_name"

    local expected_kernel_name='MYKERNEL2'

    if uname -v | grep -q "$expected_kernel_name"; then
	warn 'The kernel seems to be already installed. Nothing to do'
	return 0
    fi

    local config_path="/usr/src/sys/arch/$(uname -m)/conf/"
    if [ ! -e "$config_path" ]; then
	warn 'There is no sources to compile the kernel.'
	warn 'Go to https://www.netbsd.org/docs/guide/en/chap-fetch.html'
	warn 'to check how to obtain the sources'
	return 1
    fi
    cd $config_path
    pwd

    cp GENERIC $expected_kernel_name
    sed -i "s~^#vio9p~vio9p~" $expected_kernel_name
    config $expected_kernel_name && \
	cd ../compile/$expected_kernel_name && \
	make depend && \
	make && \
	mv /netbsd /netbsd.backup && \
	mv netbsd /
	
    if [ $? != 0 ]; then
	warn 'Something went bananas while compiling and installing the kernel'
	return 1
    fi

    info 'Now the machine will be rebooted'
    info 'After that, run the script again to continue this process'
    shutdown -r +1
}

#############################################################
#          2 - MOUNT SHARED DIR
#############################################################
mount_virtio9p_share() {
    local step_name='STEP 2: MOUNT VIRTIO 9P SHARED DIR'
    warn "Press enter to proceed with $step_name"; read confirm
    info "$step_name"

    local service_name='share'
    local config_file="/etc/rc.d/${service_name}"
    
    cd /dev && sh MAKEDEV vio9p0

    if [ $? != 0 ]; then
	warn 'MAKEDEV failed'
	return 1
    fi

    cat <<'EOF' > ${config_file}
#!/bin/sh
#
# PROVIDE: share
# REQUIRE: DAEMON
# KEYWORD: shutdown

. /etc/rc.subr

name="share"
rcvar="$name"
command="mount_9p -cu /dev/vio9p0 /mnt"
start_cmd="share_start"
stop_cmd=":"

share_start() {
	echo "Mounting vio9p0 file share to /mnt"
	${command}
}

load_rc_config $name
run_rc_command "$1"
EOF

    local system_config='/etc/rc.conf'
    local service_enable="$service_name=YES"

    cat $system_config | grep -q "$service_enable" \
	|| echo "$service_enable" >> $system_config

    info 'STEP 2 is done!'
    info 'Now the machine will be rebooted'
    info 'Once rebooted, run `ls /mnt` to check if the fileshare is mounted'
    shutdown -r +1
}

info "$doc"

install_kernel_with_vio9p \
    && mount_virtio9p_share