#!/bin/sh
# Keep the xcatd SysV init script only on systems that actually use a
# legacy init implementation.  XCAT_COMPAT_ROOT is used by image builders
# and tests to operate on a target root without chrooting into it.

compat_root=${XCAT_COMPAT_ROOT:-}
compat_root=${compat_root%/}
xcat_root=${XCATROOT:-/opt/xcat}

case "$xcat_root" in
    /*) ;;
    *)
        echo "XCATROOT must be an absolute path" >&2
        exit 2
        ;;
esac

legacy_init="$compat_root/etc/init.d/xcatd"
legacy_template="$compat_root$xcat_root/share/xcat/scripts/xcatd"

uses_systemd_os_release()
{
    os_release="$compat_root/etc/os-release"
    [ -r "$os_release" ] || return 1

    os_id=
    os_version=
    while IFS='=' read -r key value; do
        value=${value#\"}
        value=${value%\"}
        value=${value#\'}
        value=${value%\'}
        case "$key" in
            ID) os_id=$value ;;
            VERSION_ID) os_version=$value ;;
        esac
    done < "$os_release"

    # Debian testing/sid intentionally omits VERSION_ID.
    if [ "$os_id" = "debian" ] && [ -z "$os_version" ]; then
        return 0
    fi

    os_major=${os_version%%.*}
    case "$os_major" in
        ''|*[!0-9]*) return 1 ;;
    esac

    case "$os_id" in
        rhel|centos|rocky|almalinux|ol|scientific)
            [ "$os_major" -ge 7 ]
            ;;
        fedora|ubuntu)
            [ "$os_major" -ge 15 ]
            ;;
        debian)
            [ "$os_major" -ge 8 ]
            ;;
        sles|sled|opensuse|opensuse-leap|opensuse-tumbleweed)
            [ "$os_major" -ge 12 ]
            ;;
        *)
            return 1
            ;;
    esac
}

uses_systemd()
{
    if [ -d "$compat_root/run/systemd/system" ]; then
        return 0
    fi

    # Chroots and minimal images may have systemd installed without a running
    # manager or an /sbin/init link.
    if [ -x "$compat_root/usr/lib/systemd/systemd" ] ||
        [ -x "$compat_root/lib/systemd/systemd" ]; then
        return 0
    fi

    if uses_systemd_os_release; then
        return 0
    fi

    if [ -L "$compat_root/sbin/init" ]; then
        init_target=$(readlink "$compat_root/sbin/init" 2>/dev/null || true)
        case "$init_target" in
            *systemd*) return 0 ;;
        esac
    fi

    return 1
}

configure_legacy_init()
{
    replace_existing=${1:-}

    if uses_systemd; then
        rm -f "$legacy_init"
        return
    fi

    # A broken link cannot provide a usable init script.  Replace it while
    # preserving links whose administrator-managed target still exists.
    if [ -L "$legacy_init" ] && [ ! -e "$legacy_init" ]; then
        rm -f "$legacy_init"
    fi

    if [ -e "$legacy_init" ] || [ -L "$legacy_init" ]; then
        if [ "$replace_existing" != "--replace" ]; then
            return
        fi
        rm -f "$legacy_init"
    fi

    if [ ! -r "$legacy_template" ]; then
        echo "Legacy xcatd init template not found: $legacy_template" >&2
        exit 1
    fi

    mkdir -p "$compat_root/etc/init.d"
    cp "$legacy_template" "$legacy_init"
    chmod 755 "$legacy_init"
}

case "${1:-}" in
    uses-systemd)
        uses_systemd
        ;;
    configure)
        case "${2:-}" in
            ''|--replace) ;;
            *)
                echo "Usage: $0 {uses-systemd|configure [--replace]|remove}" >&2
                exit 2
                ;;
        esac
        configure_legacy_init "${2:-}"
        ;;
    remove)
        rm -f "$legacy_init"
        ;;
    *)
        echo "Usage: $0 {uses-systemd|configure [--replace]|remove}" >&2
        exit 2
        ;;
esac