#!/bin/sh -euf

# Copyright 2013 Intel Corporation
# Author: Artem Bityutskiy
# License: GPLv2

PROG="setup-gummiboot-conf"
VER="1.0"

srcdir="$(readlink -ev -- ${0%/*})"
. "$srcdir/setup-ivi-sh-functions"

# This is a small trick which I use to make sure my scripts are portable -
# check if 'dash' is present, and if yes - use it.
if can_switch_to_dash; then
	exec dash -euf "$srcdir/$PROG" "$@"
	exit $?
fi

# Common preparations for all subcommands.
prepare()
{
	verbose "Boot directory is $bootdir"
	[ -d "$bootdir" ] || \
		fatal "boot directory path \"$bootdir\" does not exist"

	# The gummiboot configuration directory
	conf_dir="$bootdir/loader"
	# The gummiboot configuration file
	conf_file="$conf_dir/loader.conf"
	# The gummiboot kernel entries directory
	entries_dir="$bootdir/loader/entries"
}

# Get a regular expression for matching gummiboot configuration file option
# "$1"
get_regexp()
{
	local opt="$(esc_regexp "$1")"

	opt="$(case_insensitive_regexp "$opt")"
	printf "%s" "\(^[[:blank:]]*$opt[[:blank:]]\+\)\([^[:blank:]]\+\)\([[:blank:]]*$\)"
}

# Create the default gummiboot configuration file.
create_default_conf_file()
{
	verbose "creating the default configuration file \"$conf_file\""

	mkdir -p $verbose "$conf_dir" >&2
	cat > "$conf_file" <<-EOF
	# Generated by $PROG
	timeout 0
	default $1
	EOF
}

# Check wheter the gummiboot configuration file exist, and if not:
#   o create the default one if --force option was specified
#   o fail if no --force option was specified
check_and_create_default_conf_file()
{
	if [ -s "$conf_file" ]; then
		return 0
	fi

	if [ -n "$force" ]; then
		create_default_conf_file "$1"
	else
		fatal "cannot find the gummiboot configuration file" \
		      "(\"$conf_file\") (use -f to create the default" \
		      "one)"
	fi
}

#
# -----------------------------------------------------------------------------
# The "add" subcommand
# -----------------------------------------------------------------------------
#

show_add_usage()
{
	cat <<-EOF
Usage: $PROG add [options] <entry> <title> <kernel> <options>

Add a new gummiboot entry. The mandatory arguments are:

    <entry>   - name of the gummiboot entry to add
                (<bootdir>/loader/entries/<entry>.conf)
    <title>   - the title of the entry
    <kernel>  - name of the kernel binary to add the entry for
                (<bootdir>/<kernel>)
    <options> - kernel boot options

Options:
  -f, --force  if the entry already exists - re-write it, if
	       <bootdir>/loader/loader.conf does not exist - create one,
	       if <bootdir>/<kernel> does not exist - do not fail
  -h, --help   show this text and exit
EOF
}

show_add_usage_fail()
{
	IFS= printf "%s\n\n" "$PROG: error: $*" >&2
	show_add_usage >&2
	exit 1
}

add_subcommand()
{
	if [ "$#" -eq 0  ]; then
		show_add_usage
		exit 0
	fi

	local tmp
	tmp=`getopt -n $PROG -o f,h --long force,help -- "$@"` ||
		show_add_usage_fail "cannot parse command-line options"
	eval set -- "$tmp"

	local force=
	while true; do
		case "$1" in
		-f|--force)
			force="-f"
			;;
		-h|--help)
			show_add_usage
			exit 0
			;;
		--) shift; break
			;;
		*) show_add_usage_fail "unrecognized option \"$1\""
			;;
		esac
		shift
	done

	if [ "$#" -lt 4 ]; then
		show_add_usage_fail "too little arguments"
	fi
	if [ "$#" -gt 4 ]; then
		show_add_usage_fail "too many arguments: \"$1\""
	fi

	prepare

	local entry="$1"; shift
	local title="$1"; shift
	local kernel="$1"; shift
	local options="$1"; shift
	local kernel_path="$bootdir/$kernel"
	local entry_path="$entries_dir/${entry}.conf"

	verbose "entry is \"$entry\""
	verbose "title is \"$title\""
	verbose "kernel is \"$kernel\""
	verbose "options are \"$options\""

	if [ -f "$entry_path" ] && [ -z "$force" ]; then
		fatal "gummiboot entry \"$entry_path\" already exists" \
		      "(use -f to force re-creating it)"
	fi

	if ! [ -f "$kernel_path" ] && [ -z "$force" ]; then
		fatal "cannot find kernel \"$kernel_path\"" \
		      "(use -f to ignore this error)"
	fi

	# Make sure the gummiboot configuration file exists
	check_and_create_default_conf_file "$entry"

	# Find out the kernel version from its name
	local kernel_version="$(printf "%s" "$kernel" | LC_ALL=C \
		   sed -e 's/[^[:digit:]]\+-\([[:digit:]]\+.*\)/\1/')"
	[ -n "$kernel_version" ] || \
		fatal "cannot fetch kernel version from \"$kernel\""

	# Create the new entry
	mkdir -p $verbose "$entries_dir" >&2
	cat > "$entry_path" <<-EOF
	# Generated by $PROG
	title $title
	version $kernel_version
	efi /$kernel
	options $options
	EOF

	if [ -n "$verbose" ]; then
		verbose "contents of \"$entry_path\":"
		cat "$entry_path" >&2
	fi
}

#
# -----------------------------------------------------------------------------
# The "remove" subcommand
# -----------------------------------------------------------------------------
#

show_remove_usage()
{
	cat <<-EOF
Usage: $PROG remove [options] <entry>

Delete gummiboot entry <entry> (<bootdir>/loader/entries/<entry>.conf).

Options:
  -f, --force  do not fail if the entry doesn't exist
  -h, --help   show this text and exit
EOF
}

show_remove_usage_fail()
{
	IFS= printf "%s\n\n" "$PROG: error: $*" >&2
	show_remove_usage >&2
	exit 1
}

remove_subcommand()
{
	if [ "$#" -eq 0  ]; then
		show_remove_usage
		exit 0
	fi

	local tmp
	tmp=`getopt -n $PROG -o f,h --long force,help -- "$@"` ||
		show_remove_usage_fail "cannot parse command-line options"
	eval set -- "$tmp"

	local force=
	while true; do
		case "$1" in
		-f|--force)
			force="-f"
			;;
		-h|--help)
			show_remove_usage
			exit 0
			;;
		--) shift; break
			;;
		*) show_remove_usage_fail "unrecognized option \"$1\""
			;;
		esac
		shift
	done

	if [ "$#" -lt 1 ]; then
		show_remove_usage_fail "too little arguments"
	fi
	if [ "$#" -gt 1 ]; then
		show_remove_usage_fail "too many arguments: \"$1\""
	fi

	prepare

	local entry="$1"
	local entry_path="$entries_dir/${entry}.conf"

	if ! [ -f "$entry_path" ] && [ -z "$force" ]; then
		fatal "gummiboot entry \"$entry_path\" doesn't exist" \
		      "(use -f to ignore this error)"
	fi

	rm -rf $verbose "$entry_path" >&2
	verbose "removed $entry_path"
}

#
# -----------------------------------------------------------------------------
# The "default" subcommand
# -----------------------------------------------------------------------------
#

# Get the kernel name from a gummiboot entry
get_kernel_from_entry()
{
	local result=
	local entry="$entries_dir/$1.conf"

	if [ -f "$entry" ]; then
		local regexp="$(get_regexp "efi")"
		local result="$(LC_ALL=C sed -n -e "s/$regexp/\2/p" "$entry")"

		if [ -z "$result" ]; then
			regexp="$(get_regexp "linux")"
			result="$(LC_ALL=C sed -n -e "s/$regexp/\2/p" "$entry")"

			[ -n "$result" ] || return 0
		fi
	fi

	printf "%s" "${result##*/}"
}

show_default_usage()
{
	cat <<-EOF
Usage: $PROG default [options] <entry>

Set the default boot kernel to <entry>, which is the gummiboot entry name to
become the default (without the ".conf" suffix, like in
<bootdir>/loader/entries/<entry>.conf). If <entry> is omited, this command
prints the currently default entry name.

Options:
  -f, --force  if <bootdir>/loader/loader.conf does not exist - create the
               default one, if <bootdir>/loader/entries/<entry>.conf does not
	       exist - do not fail
  -h, --help   show this text and exit
EOF
}

show_default_usage_fail()
{
	IFS= printf "%s\n\n" "$PROG: error: $*" >&2
	show_default_usage >&2
	exit 1
}

default_subcommand()
{
	local tmp
	tmp=`getopt -n $PROG -o f,h --long force,help -- "$@"` ||
		show_default_usage_fail "cannot parse command-line options"
	eval set -- "$tmp"

	local force=
	while true; do
		case "$1" in
		-f|--force)
			force="-f"
			;;
		-h|--help)
			show_default_usage
			exit 0
			;;
		--) shift; break
			;;
		*) show_default_usage_fail "unrecognized option \"$1\""
			;;
		esac
		shift
	done

	if [ "$#" -gt 1 ]; then
		show_default_usage_fail "too many arguments: \"$1\""
	fi

	prepare

	local entry="${1:-}";

	# Make sure the gummiboot configuration file exists
	check_and_create_default_conf_file "$entry"

	# Find the current default entry
	local regexp="$(get_regexp "default")"
	local default_entry="$(LC_ALL=C sed -n -e "s/$regexp/\2/p" "$conf_file")"

	if [ -z "$entry" ]; then
		printf "%s\n" "entry: $default_entry"
		printf "%s\n" "kernel: $(get_kernel_from_entry "$default_entry")"
		return 0
	fi

	local entry_path="$entries_dir/${entry}.conf"
	if ! [ -f "$entry_path" ] && [ -z "$force" ]; then
		fatal "cannot find the gummiboot entry \"$entry_path\"" \
		      "(use -f to ignore this error)"
	fi

	if [ -z "$default_entry" ]; then
		verbose "no default entry found, adding \"$entry\""
		printf "%s" "default $entry" >> "$conf_file"
		return 0
	fi

	[ "$(printf "%s\n" "$default_entry" | wc -l)" -eq "1" ] || \
		fatal "more than one default entry in \"$conf_file\""

	# Escape special sed characters in "$entry" and replace the old default
	# entry with the new one
	local entry_esc="$(esc_sed_replacement "$entry")"
	LC_ALL=C sed -i -e "s/$regexp/\1$entry_esc\3/" "$conf_file"

	verbose "set the default boot kernel to \"$entry"\"
}

#
# -----------------------------------------------------------------------------
#

show_usage()
{
	cat <<-EOF
Usage: $PROG [options] <subcommand> [options] <arguments>

This program changes the gummiboot bootloader configuration. Supported
subcommands are:
   add     - add a gummiboot entry for a kernel
   remove  - remove a gummiboot entry
   default - get or set the default gummiboot entry

Run "$PROG <subcommand>" to see subcommand-specific help.

Options:
  -b, --bootdir  path to the boot directory (default is "/boot")
  --version      show the program version and exit
  -v, --verbose  be verbose
  -h, --help     show this text and exit
EOF
}

show_usage_fail()
{
	IFS= printf "%s\n\n" "$PROG: error: $*" >&2
	show_usage >&2
	exit 1
}

bootdir="/boot"
verbose=
while [ -n "${1:-""}" ] && [ -z "${1##-*}" ]; do
	case "$1" in
	-b|--bootdir)
		shift
		# If there is no argument or it starts with "-", complain
		if [ -z "${1:-""}" ] || [ -z "${1##-*}" ]; then
			fatal "--bootdir requires an argument"
		fi
		bootdir="$1"
		;;
	--version)
		printf "%s\n" "$VER"
		exit 0
		;;
	-v|--verbose)
		verbose="-v"
		;;
	-h|--help)
		show_usage
		exit 0
		;;
	--) shift; break
		;;
	*) show_usage_fail "unrecognized option \"$1\""
		;;
	esac
	shift
done

# Parse subcommands

if [ "$#" -eq 0 ]; then
	show_usage
	exit 0
fi


subcommand="$1"; shift

case "$subcommand" in
add)
	add_subcommand "$@"
	break
	;;
remove)
	remove_subcommand "$@"
	break
	;;
default)
	default_subcommand "$@"
	break
	;;
*) show_usage_fail "unrecognized subcommand \"$subcommand\""
	;;
esac