Migrate check_users to new ouput infrastructure

5 files changed, 323 insertions, 130 deletions

diff --git a/plugins/Makefile.am b/plugins/Makefile.am
index d43c1971..e0069653 100644
--- a/plugins/Makefile.am
+++ b/plugins/Makefile.am
@@ -125,6 +125,7 @@ check_time_LDADD = $(NETLIBS)
 check_ntp_time_LDADD = $(NETLIBS) $(MATHLIBS)
 check_ups_LDADD = $(NETLIBS)
 check_users_LDADD = $(BASEOBJS) $(WTSAPI32LIBS) $(SYSTEMDLIBS)
+check_users_SOURCES = check_users.c check_users.d/users.c
 check_by_ssh_LDADD = $(NETLIBS)
 check_ide_smart_LDADD = $(BASEOBJS)
 negate_LDADD = $(BASEOBJS)
diff --git a/plugins/check_users.c b/plugins/check_users.c
index f1e1c39d..6ec87d21 100644
--- a/plugins/check_users.c
+++ b/plugins/check_users.c
@@ -3,7 +3,7 @@
  * Monitoring check_users plugin
  *
  * License: GPL
- * Copyright (c) 2000-2024 Monitoring Plugins Development Team
+ * Copyright (c) 2000-2025 Monitoring Plugins Development Team
  *
  * Description:
  *
@@ -30,12 +30,19 @@
  *
  *****************************************************************************/
 
+#include "check_users.d/config.h"
+#include "thresholds.h"
 const char *progname = "check_users";
-const char *copyright = "2000-2024";
+const char *copyright = "2000-2025";
 const char *email = "devel@monitoring-plugins.org";
 
-#include "common.h"
-#include "utils.h"
+#include "check_users.d/users.h"
+#include "output.h"
+#include "perfdata.h"
+#include "states.h"
+#include "utils_base.h"
+#include "./common.h"
+#include "./utils.h"
 
 #if HAVE_WTSAPI32_H
 #       include <windows.h>
@@ -53,29 +60,16 @@ const char *email = "devel@monitoring-plugins.org";
 #       include <systemd/sd-login.h>
 #endif
 
-#define possibly_set(a, b) ((a) == 0 ? (b) : 0)
+typedef struct process_argument_wrapper {
+        int errorcode;
+        check_users_config config;
+} process_argument_wrapper;
 
-static int process_arguments(int, char **);
-static void print_help(void);
+process_argument_wrapper process_arguments(int /*argc*/, char ** /*argv*/);
+void print_help(void);
 void print_usage(void);
 
-static char *warning_range = NULL;
-static char *critical_range = NULL;
-static thresholds *thlds = NULL;
-
 int main(int argc, char **argv) {
-        int users = -1;
-        int result = STATE_UNKNOWN;
-#if HAVE_WTSAPI32_H
-        WTS_SESSION_INFO *wtsinfo;
-        DWORD wtscount;
-        DWORD index;
-#elif HAVE_UTMPX_H
-        struct utmpx *putmpx;
-#else
-        char input_buffer[MAX_INPUT_BUFFER];
-#endif
-
         setlocale(LC_ALL, "");
         bindtextdomain(PACKAGE, LOCALEDIR);
         textdomain(PACKAGE);
@@ -83,121 +77,106 @@ int main(int argc, char **argv) {
         /* Parse extra opts if any */
         argv = np_extra_opts(&argc, argv, progname);
 
-        if (process_arguments(argc, argv) == ERROR)
-                usage4(_("Could not parse arguments"));
-
-        users = 0;
-
-#ifdef HAVE_LIBSYSTEMD
-        if (sd_booted() > 0)
-                users = sd_get_sessions(NULL);
-        else {
-#endif
-#if HAVE_WTSAPI32_H
-                if (!WTSEnumerateSessions(WTS_CURRENT_SERVER_HANDLE, 0, 1, &wtsinfo, &wtscount)) {
-                        printf(_("Could not enumerate RD sessions: %d\n"), GetLastError());
-                        return STATE_UNKNOWN;
-                }
-
-                for (index = 0; index < wtscount; index++) {
-                        LPTSTR username;
-                        DWORD size;
-                        int len;
-
-                        if (!WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, wtsinfo[index].SessionId, WTSUserName, &username, &size))
-                                continue;
-
-                        len = lstrlen(username);
-
-                        WTSFreeMemory(username);
-
-                        if (len == 0)
-                                continue;
-
-                        if (wtsinfo[index].State == WTSActive || wtsinfo[index].State == WTSDisconnected)
-                                users++;
-                }
-
-                WTSFreeMemory(wtsinfo);
-#elif HAVE_UTMPX_H
-        /* get currently logged users from utmpx */
-        setutxent();
-
-        while ((putmpx = getutxent()) != NULL)
-                if (putmpx->ut_type == USER_PROCESS)
-                        users++;
-
-        endutxent();
-#else
-        /* run the command */
-        child_process = spopen(WHO_COMMAND);
-        if (child_process == NULL) {
-                printf(_("Could not open pipe: %s\n"), WHO_COMMAND);
-                return STATE_UNKNOWN;
-        }
-
-        child_stderr = fdopen(child_stderr_array[fileno(child_process)], "r");
-        if (child_stderr == NULL)
-                printf(_("Could not open stderr for %s\n"), WHO_COMMAND);
+        process_argument_wrapper tmp = process_arguments(argc, argv);
 
-        while (fgets(input_buffer, MAX_INPUT_BUFFER - 1, child_process)) {
-                /* increment 'users' on all lines except total user count */
-                if (input_buffer[0] != '#') {
-                        users++;
-                        continue;
-                }
-
-                /* get total logged in users */
-                if (sscanf(input_buffer, _("# users=%d"), &users) == 1)
-                        break;
+        if (tmp.errorcode == ERROR) {
+                usage4(_("Could not parse arguments"));
         }
 
-        /* check STDERR */
-        if (fgets(input_buffer, MAX_INPUT_BUFFER - 1, child_stderr))
-                result = possibly_set(result, STATE_UNKNOWN);
-        (void)fclose(child_stderr);
+        check_users_config config = tmp.config;
 
-        /* close the pipe */
-        if (spclose(child_process))
-                result = possibly_set(result, STATE_UNKNOWN);
-#endif
-#ifdef HAVE_LIBSYSTEMD
+#ifdef _WIN32
+#       if HAVE_WTSAPI32_H
+        get_num_of_users_wrapper user_wrapper = get_num_of_users_windows();
+#       else
+#               error Did not find WTSAPI32
+#       endif // HAVE_WTSAPI32_H
+#else
+#       ifdef HAVE_LIBSYSTEMD
+        get_num_of_users_wrapper user_wrapper = get_num_of_users_systemd();
+#       elif HAVE_UTMPX_H
+        get_num_of_users_wrapper user_wrapper = get_num_of_users_utmp();
+#       else  // !HAVE_LIBSYSTEMD && !HAVE_UTMPX_H
+        get_num_of_users_wrapper user_wrapper = get_num_of_users_who_command();
+#       endif // HAVE_LIBSYSTEMD
+#endif     // _WIN32
+
+        mp_check overall = mp_check_init();
+        mp_subcheck sc_users = mp_subcheck_init();
+
+        if (user_wrapper.errorcode != 0) {
+                sc_users = mp_set_subcheck_state(sc_users, STATE_UNKNOWN);
+                sc_users.output = "Failed to retrieve number of users";
+                mp_add_subcheck_to_check(&overall, sc_users);
+                mp_exit(overall);
         }
-#endif
-
         /* check the user count against warning and critical thresholds */
-        result = get_status((double)users, thlds);
 
-        if (result == STATE_UNKNOWN)
-                printf("%s\n", _("Unable to read output"));
-        else {
-                printf(_("USERS %s - %d users currently logged in |%s\n"), state_text(result), users,
-                           sperfdata_int("users", users, "", warning_range, critical_range, true, 0, false, 0));
+        mp_perfdata users_pd = {
+                .label = "users",
+                .value = mp_create_pd_value(user_wrapper.users),
+        };
+
+        users_pd = mp_pd_set_thresholds(users_pd, config.thresholds);
+        mp_add_perfdata_to_subcheck(&sc_users, users_pd);
+
+        int tmp_status = mp_get_pd_status(users_pd);
+        sc_users = mp_set_subcheck_state(sc_users, tmp_status);
+
+        switch (tmp_status) {
+        case STATE_WARNING:
+                xasprintf(&sc_users.output, "%d users currently logged in. This violates the warning threshold", user_wrapper.users);
+                break;
+        case STATE_CRITICAL:
+                xasprintf(&sc_users.output, "%d users currently logged in. This violates the critical threshold", user_wrapper.users);
+                break;
+        default:
+                xasprintf(&sc_users.output, "%d users currently logged in", user_wrapper.users);
         }
 
-        return result;
+        mp_add_subcheck_to_check(&overall, sc_users);
+        mp_exit(overall);
 }
 
+#define output_format_index CHAR_MAX + 1
+
 /* process command-line arguments */
-int process_arguments(int argc, char **argv) {
+process_argument_wrapper process_arguments(int argc, char **argv) {
         static struct option longopts[] = {{"critical", required_argument, 0, 'c'},
                                                                            {"warning", required_argument, 0, 'w'},
                                                                            {"version", no_argument, 0, 'V'},
                                                                            {"help", no_argument, 0, 'h'},
+                                                                           {"output-format", required_argument, 0, output_format_index},
                                                                            {0, 0, 0, 0}};
 
-        if (argc < 2)
+        if (argc < 2) {
                 usage("\n");
+        }
+
+        char *warning_range = NULL;
+        char *critical_range = NULL;
+        check_users_config config = check_users_config_init();
 
-        int option_char;
         while (true) {
-                int option = 0;
-                option_char = getopt_long(argc, argv, "+hVvc:w:", longopts, &option);
+                int counter = getopt_long(argc, argv, "+hVvc:w:", longopts, NULL);
 
-                if (option_char == -1 || option_char == EOF || option_char == 1)
+                if (counter == -1 || counter == EOF || counter == 1) {
                         break;
+                }
 
-                switch (option_char) {
+                switch (counter) {
+                case output_format_index: {
+                        parsed_output_format parser = mp_parse_output_format(optarg);
+                        if (!parser.parsing_success) {
+                                // TODO List all available formats here, maybe add anothoer usage function
+                                printf("Invalid output format: %s\n", optarg);
+                                exit(STATE_UNKNOWN);
+                        }
+
+                        config.output_format_is_set = true;
+                        config.output_format = parser.output_format;
+                        break;
+                }
                 case '?': /* print short usage statement if args not parsable */
                         usage5();
                 case 'h': /* help */
@@ -215,26 +194,35 @@ int process_arguments(int argc, char **argv) {
                 }
         }
 
-        option_char = optind;
-
-        if (warning_range == NULL && argc > option_char)
-                warning_range = argv[option_char++];
-
-        if (critical_range == NULL && argc > option_char)
-                critical_range = argv[option_char++];
-
-        /* this will abort in case of invalid ranges */
-        set_thresholds(&thlds, warning_range, critical_range);
-
-        if (!thlds->warning) {
-                usage4(_("Warning threshold must be a valid range expression"));
+        // TODO add proper verification for ranges here!
+        if (warning_range) {
+                mp_range_parsed tmp = mp_parse_range_string(warning_range);
+                if (tmp.error == MP_PARSING_SUCCES) {
+                        config.thresholds.warning = tmp.range;
+                        config.thresholds.warning_is_set = true;
+                } else {
+                        printf("Failed to parse warning range: %s", warning_range);
+                        exit(STATE_UNKNOWN);
+                }
         }
 
-        if (!thlds->critical) {
-                usage4(_("Critical threshold must be a valid range expression"));
+        if (critical_range) {
+                mp_range_parsed tmp = mp_parse_range_string(critical_range);
+                if (tmp.error == MP_PARSING_SUCCES) {
+                        config.thresholds.critical = tmp.range;
+                        config.thresholds.critical_is_set = true;
+                } else {
+                        printf("Failed to parse critical range: %s", critical_range);
+                        exit(STATE_UNKNOWN);
+                }
         }
 
-        return OK;
+        process_argument_wrapper result = {
+                .errorcode = OK,
+                .config = config,
+        };
+
+        return result;
 }
 
 void print_help(void) {
@@ -257,6 +245,7 @@ void print_help(void) {
         printf("    %s\n", _("Set WARNING status if number of logged in users violates RANGE_EXPRESSION"));
         printf(" %s\n", "-c, --critical=RANGE_EXPRESSION");
         printf("    %s\n", _("Set CRITICAL status if number of logged in users violates RANGE_EXPRESSION"));
+        printf(UT_OUTPUT_FORMAT);
 
         printf(UT_SUPPORT);
 }
diff --git a/plugins/check_users.d/config.h b/plugins/check_users.d/config.h
new file mode 100644
index 00000000..35b7b7f8
--- /dev/null
+++ b/plugins/check_users.d/config.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include "output.h"
+#include "thresholds.h"
+typedef struct check_users_config {
+        mp_thresholds thresholds;
+
+        bool output_format_is_set;
+        mp_output_format output_format;
+} check_users_config;
+
+check_users_config check_users_config_init() {
+        check_users_config tmp = {
+                .thresholds = mp_thresholds_init(),
+
+                .output_format_is_set = false,
+        };
+        return tmp;
+}
diff --git a/plugins/check_users.d/users.c b/plugins/check_users.d/users.c
new file mode 100644
index 00000000..7969ae79
--- /dev/null
+++ b/plugins/check_users.d/users.c
@@ -0,0 +1,166 @@
+#include "./users.h"
+
+#ifdef _WIN32
+#       ifdef HAVE_WTSAPI32_H
+#               include <windows.h>
+#               include <wtsapi32.h>
+#               undef ERROR
+#               define ERROR -1
+
+get_num_of_users_wrapper get_num_of_users_windows() {
+        WTS_SESSION_INFO *wtsinfo;
+        DWORD wtscount;
+
+        get_num_of_users_wrapper result = {};
+
+        if (!WTSEnumerateSessions(WTS_CURRENT_SERVER_HANDLE, 0, 1, &wtsinfo, &wtscount)) {
+                // printf(_("Could not enumerate RD sessions: %d\n"), GetLastError());
+                result.error = WINDOWS_COULD_NOT_ENUMERATE_SESSIONS;
+                return result;
+        }
+
+        for (DWORD index = 0; index < wtscount; index++) {
+                LPTSTR username;
+                DWORD size;
+
+                if (!WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, wtsinfo[index].SessionId, WTSUserName, &username, &size)) {
+                        continue;
+                }
+
+                int len = lstrlen(username);
+
+                WTSFreeMemory(username);
+
+                if (len == 0) {
+                        continue;
+                }
+
+                if (wtsinfo[index].State == WTSActive || wtsinfo[index].State == WTSDisconnected) {
+                        result.users++;
+                }
+        }
+
+        WTSFreeMemory(wtsinfo);
+        return result;
+}
+#       else // HAVE_WTSAPI32_H
+#               error On windows but without the WTSAPI32 lib
+#       endif // HAVE_WTSAPI32_H
+
+#else // _WIN32
+
+#       include "../../config.h"
+
+#       ifdef HAVE_LIBSYSTEMD
+#               include <systemd/sd-daemon.h>
+#               include <systemd/sd-login.h>
+
+get_num_of_users_wrapper get_num_of_users_systemd() {
+        get_num_of_users_wrapper result = {};
+
+        // Test whether we booted with systemd
+        if (sd_booted() > 0) {
+                int users = sd_get_sessions(NULL);
+                if (users >= 0) {
+                        // Success
+                        result.users = users;
+                        return result;
+                }
+
+                // Failure! return the error code
+                result.errorcode = users;
+                return result;
+        }
+
+        // Looks like we are not running systemd,
+        // return with error here
+        result.errorcode = NO_SYSTEMD_ERROR;
+        return result;
+}
+#       endif
+
+#       ifdef HAVE_UTMPX_H
+#               include <utmpx.h>
+
+get_num_of_users_wrapper get_num_of_users_utmp() {
+        int users = 0;
+
+        /* get currently logged users from utmpx */
+        setutxent();
+
+        struct utmpx *putmpx;
+        while ((putmpx = getutxent()) != NULL) {
+                if (putmpx->ut_type == USER_PROCESS) {
+                        users++;
+                }
+        }
+
+        endutxent();
+
+        get_num_of_users_wrapper result = {
+                .errorcode = 0,
+                .users = users,
+        };
+
+        return result;
+}
+#       endif
+
+#       ifndef HAVE_WTSAPI32_H
+#               ifndef HAVE_LIBSYSTEMD
+#                       ifndef HAVE_UTMPX_H
+//  Fall back option here for the others (probably still not on windows)
+
+#                               include "../popen.h"
+#                               include "../common.h"
+#                               include "../utils.h"
+
+get_num_of_users_wrapper get_num_of_users_who_command() {
+        /* run the command */
+        child_process = spopen(WHO_COMMAND);
+        if (child_process == NULL) {
+                // printf(_("Could not open pipe: %s\n"), WHO_COMMAND);
+                get_num_of_users_wrapper result = {
+                        .errorcode = COULD_NOT_OPEN_PIPE,
+                };
+                return result;
+        }
+
+        child_stderr = fdopen(child_stderr_array[fileno(child_process)], "r");
+        if (child_stderr == NULL) {
+                // printf(_("Could not open stderr for %s\n"), WHO_COMMAND);
+                //  TODO this error should probably be reported
+        }
+
+        get_num_of_users_wrapper result = {};
+        char input_buffer[MAX_INPUT_BUFFER];
+        while (fgets(input_buffer, MAX_INPUT_BUFFER - 1, child_process)) {
+                /* increment 'users' on all lines except total user count */
+                if (input_buffer[0] != '#') {
+                        result.users++;
+                        continue;
+                }
+
+                /* get total logged in users */
+                if (sscanf(input_buffer, _("# users=%d"), &result.users) == 1) {
+                        break;
+                }
+        }
+
+        /* check STDERR */
+        if (fgets(input_buffer, MAX_INPUT_BUFFER - 1, child_stderr)) {
+                // if this fails, something broke and the result can not be relied upon or so is the theorie here
+                result.errorcode = STDERR_COULD_NOT_BE_READ;
+        }
+        (void)fclose(child_stderr);
+
+        /* close the pipe */
+        spclose(child_process);
+
+        return result;
+}
+
+#                       endif
+#               endif
+#       endif
+#endif
diff --git a/plugins/check_users.d/users.h b/plugins/check_users.d/users.h
new file mode 100644
index 00000000..aacba775
--- /dev/null
+++ b/plugins/check_users.d/users.h
@@ -0,0 +1,18 @@
+#pragma once
+
+typedef struct get_num_of_users_wrapper {
+        int errorcode;
+        int users;
+} get_num_of_users_wrapper;
+
+enum {
+        NO_SYSTEMD_ERROR = 64,
+        WINDOWS_COULD_NOT_ENUMERATE_SESSIONS,
+        COULD_NOT_OPEN_PIPE,
+        STDERR_COULD_NOT_BE_READ,
+};
+
+get_num_of_users_wrapper get_num_of_users_systemd();
+get_num_of_users_wrapper get_num_of_users_utmp();
+get_num_of_users_wrapper get_num_of_users_windows();
+get_num_of_users_wrapper get_num_of_users_who_command();