#!/bin/bash

# called by dracut
#
# Parses depmod configuration and calls instmods for out-of-tree kernel
# modules found.  Specifically, kernel modules inside directories that
# come from the following places are included (if these kernel modules
# are present in modules.dep):
#   - "search" configuration option;
#   - "override" configuration option (matching an exact file name constructed
#      by concatenating the provided directory and the kernel module name);
#   - "external" configuration option (if "external" is a part of "search"
#     configuration).
# (See depmod.d(5) for details.)
#
# This module has the following variables available for configuration:
#   - "depmod_modules_dep" - Path to the modules.dep file
#                            ("$srcmods/modules.dep" by default);
#   - "depmod_module_dir" - Directory containing kernel modules ("$srcmods"
#                           by default);
#   - "depmod_configs" - array of depmod configuration paths to parse
#                        (as supplied to depmod -C, ("/run/depmod.d/"
#                        "/etc/depmod.d/" "/lib/depmod.d/") by default).
installkernel() {
    : "${depmod_modules_dep:=$srcmods/modules.dep}"
    : "${depmod_module_dir:=$srcmods}"

    [[ -f ${depmod_modules_dep} ]] || return 0

    # Message printers with custom prefix
    local mod_name="kernel-modules-extra"
    prinfo() { dinfo "  ${mod_name}: $*"; }
    prdebug() { ddebug "  ${mod_name}: $*"; }

    # Escape a string for usage as a part of extended regular expression.
    # $1 - string to escape
    re_escape() {
        printf "%s" "$1" | sed 's/\([.+?^$\/\\|()\[]\|\]\)/\\\0/'
    }

    local cfg
    local cfgs=()
    local search_list=""
    local overrides=()
    local external_dirs=()
    local e f

    ## Gathering and sorting configuration file list

    [ -n "${depmod_configs[*]-}" ] \
        || depmod_configs=(/run/depmod.d /etc/depmod.d /lib/depmod.d)

    for cfg in "${depmod_configs[@]}"; do
        [ -e "$cfg" ] || {
            prdebug "configuration source \"$cfg\" does not exist"
            continue
        }

        # '/' is used as a separator between configuration name and
        # configuration path
        if [ -d "$cfg" ]; then
            for f in "$cfg/"*.conf; do
                [[ -e $f && ! -d $f ]] || {
                    prdebug "configuration source" \
                        "\"$cfg\" is ignored" \
                        "(directory or doesn't exist)"
                    continue
                }
                cfgs+=("${f##*/}/$f")
            done
        else
            cfgs+=("${cfg##*/}/$cfg")
        fi
    done

    if ((${#cfgs[@]} > 0)); then
        mapfile -t cfgs < <(printf '%s\n' "${cfgs[@]}" | LANG=C sort -u -k1,1 -t '/' | cut -f 2- -d '/')
    fi

    ## Parse configurations

    for cfg in "${cfgs[@]}"; do
        prdebug "parsing configuration file \"$cfg\""

        local k v mod kverpat path
        while read -r k v; do
            case "$k" in
                search)
                    search_list="$search_list $v"
                    prdebug "$cfg: added \"$v\" to the list of" \
                        "search directories"
                    ;;
                override) # module_name kver_pattern dir
                    read -r mod kverpat path <<< "$v"

                    if [[ ! $mod || ! $kverpat || ! $path ]]; then
                        prinfo "$cfg: ignoring incorrect" \
                            "override option: \"$k $v\""
                        continue
                    fi

                    if [[ '*' == "$kverpat" ]] \
                        || [[ $kernel =~ $kverpat ]]; then
                        overrides+=("${path}/${mod}")

                        prdebug "$cfg: added override" \
                            "\"${path}/${mod}\""
                    else
                        prdebug "$cfg: override \"$v\" is" \
                            "ignored since \"$kverpat\"" \
                            "doesn't match \"$kernel\""
                    fi
                    ;;
                external) # kverpat dir
                    read -r kverpat path <<< "$v"

                    if [[ ! $kverpat || ! $path ]]; then
                        prinfo "$cfg: ignoring incorrect" \
                            "external option: \"$k $v\""
                        continue
                    fi

                    if [[ '*' == "$kverpat" || \
                        $kernel =~ $kverpat ]]; then
                        external_dirs+=("$path")

                        prdebug "$cfg: added external" \
                            "directory \"$path\""
                    else
                        prdebug "$cfg: external directory" \
                            "\"$path\" is ignored since" \
                            "\"$kverpat\" doesn't match " \
                            "\"$kernel\""
                    fi
                    ;;
                '#'* | '') # comments and empty strings
                    ;;
                include | make_map_files) # ignored by depmod
                    ;;
                *)
                    prinfo "$cfg: unknown depmod configuration" \
                        "option \"$k $v\""
                    ;;
            esac
        done < "$cfg"
    done

    # "updates built-in" is the default search list
    : "${search_list:=updates}"

    ## Build a list of regular expressions for grepping modules.dep

    local pathlist=()
    for f in "${overrides[@]}"; do
        pathlist+=("^$(re_escape "$f")")
    done

    for f in $(printf "%s" "$search_list"); do
        # Ignoring builtin modules
        [[ $f == "built-in" ]] && continue

        if [[ $f == "external" ]]; then
            for e in "${external_dirs[@]}"; do
                pathlist+=("$(re_escape "${e%/}")/[^:]+")
            done
        fi

        pathlist+=("$(re_escape "${f%/}")/[^:]+")
    done

    ## Filter modules.dep, canonicalise the resulting filenames and supply
    ## them to instmods.

    ((${#pathlist[@]} > 0)) || return 0

    printf "^%s\.ko(\.gz|\.bz2|\.xz|\.zst)?:\n" "${pathlist[@]}" \
        | (LANG=C grep -E -o -f - -- "$depmod_modules_dep" || exit 0) \
        | tr -d ':' \
        | (
            cd "$depmod_module_dir" || exit
            xargs -r realpath -se --
        ) \
        | instmods || return 1

    return 0
}
