netdata/packaging/cmake/Modules/NetdataDetectSystemd.cmake

# CMake Module to handle all the systemd-related checks for Netdata.
#
# Copyright (c) 2024 Netdata Inc.
# SPDX-License-Identifier: GPL-3.0-or-later

macro(detect_systemd)
   find_library(SYSTEMD_LIBRARY NAMES systemd)

   set(ENABLE_DSYSTEMD_DBUS NO)
   pkg_check_modules(SYSTEMD libsystemd)

   if(SYSTEMD_FOUND)
       set(CMAKE_REQUIRED_LIBRARIES_BEFORE_SYSTEMD "${CMAKE_REQUIRED_LIBRARIES}")
       set(CMAKE_REQUIRED_LIBRARIES "${CMAKE_REQUIRED_LIBRARIES};${SYSTEMD_LIBRARIES}")

       check_c_source_compiles("
       #include <systemd/sd-journal.h>

       int main() {
           int x = SD_JOURNAL_OS_ROOT;
           return 0;
       }" HAVE_SD_JOURNAL_OS_ROOT)

       check_symbol_exists(SD_JOURNAL_OS_ROOT "systemd/sd-journal.h" HAVE_SD_JOURNAL_OS_ROOT)
       check_symbol_exists(sd_journal_open_files_fd "systemd/sd-journal.h" HAVE_SD_JOURNAL_OPEN_FILES_FD)
       check_symbol_exists(sd_journal_restart_fields "systemd/sd-journal.h" HAVE_SD_JOURNAL_RESTART_FIELDS)
       check_symbol_exists(sd_journal_get_seqnum "systemd/sd-journal.h" HAVE_SD_JOURNAL_GET_SEQNUM)

       check_symbol_exists(sd_bus_default_system "systemd/sd-bus.h" HAVE_SD_BUS_DEFAULT_SYSTEM)
       check_symbol_exists(sd_bus_call_method "systemd/sd-bus.h" HAVE_SD_BUS_CALL_METHOD)
       check_symbol_exists(sd_bus_message_enter_container "systemd/sd-bus.h" HAVE_SD_BUS_MESSAGE_ENTER_CONTAINER)
       check_symbol_exists(sd_bus_message_read "systemd/sd-bus.h" HAVE_SD_BUS_MESSAGE_READ)
       check_symbol_exists(sd_bus_message_exit_container "systemd/sd-bus.h" HAVE_SD_BUS_MESSAGE_EXIT_CONTAINER)

       set(CMAKE_REQUIRED_LIBRARIES "${CMAKE_REQUIRED_LIBRARIES_BEFORE_SYSTEMD}")

       set(HAVE_SYSTEMD True)
       if(HAVE_SD_BUS_DEFAULT_SYSTEM AND HAVE_SD_BUS_CALL_METHOD AND HAVE_SD_BUS_MESSAGE_ENTER_CONTAINER AND HAVE_SD_BUS_MESSAGE_READ AND HAVE_SD_BUS_MESSAGE_EXIT_CONTAINER)
           set(ENABLE_SYSTEMD_DBUS YES)
       endif()
   endif()
endmacro()