#!/bin/bash
#
# lsinitcpio - dump the contents of an initramfs image
#

shopt -s extglob

die() {
    local mesg=$1; shift
    printf "error: $mesg\n" "$@"
    exit 1
}

usage() {
    cat<<USAGE
lsinitramfs %VERSION%
usage: ${0##*/} [options] <initramfs>

  Options:
   -a             analyze contents
   -h             display this help
   -v             more verbose output
   -x             extract image to disk

USAGE
    exit 1
}

in_array() {
    local item needle=$1; shift

    for item; do
      [[ "$item" == $needle ]] && return 0 # Found
    done
    return 1 # Not Found
}

decomp() {
    ${compress:-cat} ${compress:+-cd} "$@"
}

declare verbose=
declare list='--list'

while getopts ':ahvx' flag; do
    case $flag in
        a) analyze=1 ;;
        h) usage ;;
        v) verbose='--verbose'  ;;
        x) unset list ;;
        \?) die "invalid option -- '$OPTARG'" ;;
    esac
done
shift $(( OPTIND - 1 ))

declare image=$1

[[ $image ]] || usage
[[ -f $image ]] || die "$image: No such file"

# read compression type
case "$(file -b "$image")" in
    data|LZMA*) compress=lzma ;;
    gzip*) compress=gzip ;;
    bzip2*) compress=bzip2 ;;
    lzop*) compress=lzop ;;
    XZ*) compress=xz ;;
esac

if (( analyze )); then
    declare -a binaries explicitmod modules foundhooks hooks
    declare kernver ratio

    # calculate compression ratio
    if [[ $compress ]]; then
        TIMEFORMAT=%R decomptime=$({ time decomp "$image" >/dev/null; } 2>&1 )
        ratio=.$(( $(stat -c %s "$image") * 1000 /
                   $(decomp "$image" | bsdtar xOf - | wc -c) % 1000 ))
    fi

    # read contents of image
    while read -r line; do
        if [[ $line = *.ko?(.gz) ]]; then # module
            if [[ -z $kernver ]]; then
                [[ $line =~ /lib/modules/([^/]+)/ ]] && kernver=${BASH_REMATCH[1]}
            fi
            line=${line##*/}
            modules+=("${line%.ko?(.gz)}")
            continue
        elif [[ $line = ./hooks/* ]]; then
            foundhooks+=("${line##*/}")
        elif [[ $line = *@(/bin/|/sbin/)* ]]; then
            binaries+=("${line#.}")
        fi
    done < <(decomp "$image" | bsdtar tf -)

    # source and read config
    . <(decomp "$image" | bsdtar xOf - config)
    explicitmod=($MODULES)
    for hook in $HOOKS; do
        in_array "$hook" "${foundhooks[@]}" && hooks=("$hook")
    done

    # print results
    printf '==> Image: %s\n' "$(readlink -e "$image")"
    printf '==> Kernel: %s\n' "${kernver:-unknown}"

    if [[ $compress ]]; then
        printf '==> Compressed with: %s\n' "$compress"
        printf '  -> Compression ratio: %s\n' "$ratio"
        printf '  -> Estimated decompression time: %ss\n' "$decomptime"
    fi
    printf '\n'

    if (( ${#modules[*]} )); then
        printf '==> Included modules:\n'
        for mod in "${modules[@]}"; do
            printf '  %s' "$mod"
            in_array "${mod//_/-}" "${explicitmod[@]//_/-}" && printf ' [explicit]'
            printf '\n'
        done | sort | column -c$(tput cols)
        printf '\n'
    fi

    printf '==> Included binaries:\n'
    printf '  %s\n' "${binaries[@]}"
    printf '\n'

    if (( ${#hooks[*]} )); then
        printf '==> Hook run order:\n'
        printf '  %s\n' "${hooks[@]}"
        printf '\n'
    fi
else
    decomp "$image" | bsdcpio -i --quiet $verbose $list
fi

# vim: set ft=sh ts=4 sw=4 et: