#!/bin/bash

build() {
    local -a md_devs
    local dev insufficient_perms

    MODULE_FILE=$workdir/autodetect_modules

    add_if_avail() {
        local resolved

        # treat this as an alias, since ext3 might be aliased to ext4.
        IFS=$'\n' read -rd '' -a resolved < \
            <(modprobe -S "$KERNELVERSION" -R "$1" 2>/dev/null)

        if (( ${#resolved[*]} )); then
            printf '%s\n' "${resolved[@]}" >>"$MODULE_FILE"
        fi
    }

    if [[ ! -d /sys/devices ]]; then
        error "/sys does not appear to be mounted. Unable to use autodetection"
        return 1
    fi

    auto_modules >"$MODULE_FILE"

    # detect filesystem for root
    if rootfstype=$(findmnt -uno fstype "${BASEDIR:-/}"); then
        add_if_avail "$rootfstype"
    else
        error "failed to detect root filesystem"
        fs_autodetect_failed=1
    fi

    # detect filesystem for separate /usr
    if usrfstype=$(findmnt -snero fstype --tab-file "$BASEDIR/etc/fstab" /usr); then
        add_if_avail "$usrfstype"
    fi

    # look for raid devices
    shopt -s nullglob
    for dev in /sys/class/block/*/md/dev-*; do
        dev=/dev/${dev#*/dev-}

        [[ -r $dev ]] || insufficient_perms=1

        md_devs+=("$dev")
    done
    shopt -u nullglob

    # scan members of raid devices if found
    if (( ${#md_devs[*]} )); then
        (( !QUIET )) && plain "found %d raid members to scan" "${#md_devs[*]}"
        if (( ! insufficient_perms )); then
            mdadm -Esv "${md_devs[@]}" |
                sed -n 's/.*level=\([^ ]\+\) .*/\1/p' |
                sed 's/\<raid[456]\>/raid456/g' | sort -u >>"$MODULE_FILE"
        else
            warning "Insufficient permission to perform autodetection for mdadm devices"
            raid_autodetect_failed=1
        fi
    fi

    if (( !QUIET )) && [[ -s $MODULE_FILE ]]; then
        plain "caching %d modules" $(wc -l < "$MODULE_FILE")
    fi
}

help() {
    cat <<HELPEOF
This hook shrinks your initramdisk to a smaller size by autodetecting your
needed modules. Be sure to verify included modules are correct and none are
missing.  This hook must be run before other subsystem hooks in order to take
advantage of auto-detection.  Any hooks placed before 'autodetect' will be
installed in full.
HELPEOF
}

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