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 "log.h"
  27 #include "process-util.h"
  28 #include "sd-bus.h"
  29 #include "signal-util.h"
  30
  31 static int start_default_target(void) {
  32         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
  33         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
  34         int r;
  35
  36         r = bus_connect_system_systemd(&bus);
  37         if (r < 0) {
  38                 log_error_errno(r, "Failed to get D-Bus connection: %m");
  39                 return false;
  40         }
  41
  42         log_info("Starting default target");
  43
  44         /* Start these units only if we can replace base.target with it */
  45         r = sd_bus_call_method(bus,
  46                                "org.freedesktop.systemd1",
  47                                "/org/freedesktop/systemd1",
  48                                "org.freedesktop.systemd1.Manager",
  49                                "StartUnit",
  50                                &error,
  51                                NULL,
  52                                "ss", "default.target", "isolate");
  53
  54         if (r < 0)
  55                 log_error("Failed to start default target: %s", bus_error_message(&error, r));
  56
  57         return r;
  58 }
  59
  60 static void fork_wait(const char* const cmdline[]) {
  61         pid_t pid;
  62
  63         pid = fork();
  64         if (pid < 0) {
  65                 log_error_errno(errno, "fork(): %m");
  66                 return;
  67         }
  68         if (pid == 0) {
  69
  70                 /* Child */
  71
  72                 (void) reset_all_signal_handlers();
  73                 (void) reset_signal_mask();
  74                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
  75
  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         wait_for_terminate_and_warn(cmdline[0], pid, false);
  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 ^D to boot\n"
  87                 "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         int r;
  94
  95         log_set_target(LOG_TARGET_AUTO);
  96         log_parse_environment();
  97         log_open();
  98
  99         print_mode(argc > 1 ? argv[1] : "");
 100
 101         fork_wait(sulogin_cmdline);
 102
 103         r = start_default_target();
 104
 105         return r >= 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 106 }