src/sulogin-shell/sulogin-shell.c

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