src/sulogin-shell/sulogin-shell.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright © 2017 Felipe Sateler
   4 ***/
   5
   6 #include <errno.h>
   7 #include <sys/prctl.h>
   8
   9 #include "bus-util.h"
  10 #include "bus-error.h"
  11 #include "def.h"
  12 #include "log.h"
  13 #include "process-util.h"
  14 #include "sd-bus.h"
  15 #include "signal-util.h"
  16
  17 static int reload_manager(sd_bus *bus) {
  18         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
  19         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  20         int r;
  21
  22         log_info("Reloading system manager configuration");
  23
  24         r = sd_bus_message_new_method_call(
  25                         bus,
  26                         &m,
  27                         "org.freedesktop.systemd1",
  28                         "/org/freedesktop/systemd1",
  29                         "org.freedesktop.systemd1.Manager",
  30                         "Reload");
  31         if (r < 0)
  32                 return bus_log_create_error(r);
  33
  34         /* Note we use an extra-long timeout here. This is because a reload or reexec means generators are rerun which
  35          * are timed out after DEFAULT_TIMEOUT_USEC. Let's use twice that time here, so that the generators can have
  36          * their timeout, and for everything else there's the same time budget in place. */
  37
  38         r = sd_bus_call(bus, m, DEFAULT_TIMEOUT_USEC * 2, &error, NULL);
  39         if (r < 0)
  40                 return log_error_errno(r, "Failed to reload daemon: %s", bus_error_message(&error, r));
  41
  42         return 0;
  43 }
  44
  45 static int start_default_target(sd_bus *bus) {
  46         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
  47         int r;
  48
  49         log_info("Starting default target");
  50
  51         /* Start these units only if we can replace base.target with it */
  52         r = sd_bus_call_method(bus,
  53                                "org.freedesktop.systemd1",
  54                                "/org/freedesktop/systemd1",
  55                                "org.freedesktop.systemd1.Manager",
  56                                "StartUnit",
  57                                &error,
  58                                NULL,
  59                                "ss", "default.target", "isolate");
  60
  61         if (r < 0)
  62                 log_error("Failed to start default target: %s", bus_error_message(&error, r));
  63
  64         return r;
  65 }
  66
  67 static int fork_wait(const char* const cmdline[]) {
  68         pid_t pid;
  69         int r;
  70
  71         r = safe_fork("(sulogin)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG, &pid);
  72         if (r < 0)
  73                 return r;
  74         if (r == 0) {
  75                 /* Child */
  76                 execv(cmdline[0], (char**) cmdline);
  77                 log_error_errno(errno, "Failed to execute %s: %m", cmdline[0]);
  78                 _exit(EXIT_FAILURE); /* Operational error */
  79         }
  80
  81         return wait_for_terminate_and_check(cmdline[0], pid, WAIT_LOG_ABNORMAL);
  82 }
  83
  84 static void print_mode(const char* mode) {
  85         printf("You are in %s mode. After logging in, type \"journalctl -xb\" to view\n"
  86                 "system logs, \"systemctl reboot\" to reboot, \"systemctl default\" or \"exit\"\n"
  87                 "to boot into default mode.\n", mode);
  88         fflush(stdout);
  89 }
  90
  91 int main(int argc, char *argv[]) {
  92         static const char* const sulogin_cmdline[] = {SULOGIN, NULL};
  93         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
  94         int r;
  95
  96         log_set_target(LOG_TARGET_AUTO);
  97         log_parse_environment();
  98         log_open();
  99
 100         print_mode(argc > 1 ? argv[1] : "");
 101
 102         (void) fork_wait(sulogin_cmdline);
 103
 104         r = bus_connect_system_systemd(&bus);
 105         if (r < 0) {
 106                 log_warning_errno(r, "Failed to get D-Bus connection: %m");
 107                 r = 0;
 108         } else {
 109                 (void) reload_manager(bus);
 110
 111                 r = start_default_target(bus);
 112         }
 113
 114         return r >= 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 115 }