src/sulogin-shell/sulogin-shell.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2017 Felipe Sateler
   6
   7   systemd is free software; you can redistribute it and/or modify it
   8   under the terms of the GNU Lesser General Public License as published by
   9   the Free Software Foundation; either version 2.1 of the License, or
  10   (at your option) any later version.
  11
  12   systemd is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   Lesser General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  19 ***/
  20
  21 #include <errno.h>
  22 #include <sys/prctl.h>
  23
  24 #include "bus-util.h"
  25 #include "bus-error.h"
  26 #include "def.h"
  27 #include "log.h"
  28 #include "process-util.h"
  29 #include "sd-bus.h"
  30 #include "signal-util.h"
  31
  32 static int reload_manager(sd_bus *bus) {
  33         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
  34         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  35         int r;
  36
  37         log_info("Reloading system manager configuration");
  38
  39         r = sd_bus_message_new_method_call(
  40                         bus,
  41                         &m,
  42                         "org.freedesktop.systemd1",
  43                         "/org/freedesktop/systemd1",
  44                         "org.freedesktop.systemd1.Manager",
  45                         "Reload");
  46         if (r < 0)
  47                 return bus_log_create_error(r);
  48
  49         /* Note we use an extra-long timeout here. This is because a reload or reexec means generators are rerun which
  50          * are timed out after DEFAULT_TIMEOUT_USEC. Let's use twice that time here, so that the generators can have
  51          * their timeout, and for everything else there's the same time budget in place. */
  52
  53         r = sd_bus_call(bus, m, DEFAULT_TIMEOUT_USEC * 2, &error, NULL);
  54         if (r < 0)
  55                 return log_error_errno(r, "Failed to reload daemon: %s", bus_error_message(&error, r));
  56
  57         return 0;
  58 }
  59
  60 static int start_default_target(sd_bus *bus) {
  61         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
  62         int r;
  63
  64         log_info("Starting default target");
  65
  66         /* Start these units only if we can replace base.target with it */
  67         r = sd_bus_call_method(bus,
  68                                "org.freedesktop.systemd1",
  69                                "/org/freedesktop/systemd1",
  70                                "org.freedesktop.systemd1.Manager",
  71                                "StartUnit",
  72                                &error,
  73                                NULL,
  74                                "ss", "default.target", "isolate");
  75
  76         if (r < 0)
  77                 log_error("Failed to start default target: %s", bus_error_message(&error, r));
  78
  79         return r;
  80 }
  81
  82 static int fork_wait(const char* const cmdline[]) {
  83         pid_t pid;
  84
  85         pid = fork();
  86         if (pid < 0)
  87                 return log_error_errno(errno, "fork(): %m");
  88         if (pid == 0) {
  89
  90                 /* Child */
  91
  92                 (void) reset_all_signal_handlers();
  93                 (void) reset_signal_mask();
  94                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
  95
  96                 execv(cmdline[0], (char**) cmdline);
  97                 log_error_errno(errno, "Failed to execute %s: %m", cmdline[0]);
  98                 _exit(EXIT_FAILURE); /* Operational error */
  99         }
 100
 101         return wait_for_terminate_and_warn(cmdline[0], pid, false);
 102 }
 103
 104 static void print_mode(const char* mode) {
 105         printf("You are in %s mode. After logging in, type \"journalctl -xb\" to view\n"
 106                 "system logs, \"systemctl reboot\" to reboot, \"systemctl default\" or ^D to boot\n"
 107                 "into default mode.\n", mode);
 108         fflush(stdout);
 109 }
 110
 111 int main(int argc, char *argv[]) {
 112         static const char* const sulogin_cmdline[] = {SULOGIN, NULL};
 113         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 114         int r;
 115
 116         log_set_target(LOG_TARGET_AUTO);
 117         log_parse_environment();
 118         log_open();
 119
 120         print_mode(argc > 1 ? argv[1] : "");
 121
 122         (void) fork_wait(sulogin_cmdline);
 123
 124         r = bus_connect_system_systemd(&bus);
 125         if (r < 0) {
 126                 log_warning_errno(r, "Failed to get D-Bus connection: %m");
 127                 r = 0;
 128         } else {
 129                 (void) reload_manager(bus);
 130
 131                 r = start_default_target(bus);
 132         }
 133
 134         return r >= 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 135 }