src/getty-generator/getty-generator.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <string.h>
  23 #include <errno.h>
  24 #include <unistd.h>
  25
  26 #include "log.h"
  27 #include "util.h"
  28 #include "mkdir.h"
  29 #include "unit-name.h"
  30 #include "virt.h"
  31 #include "fileio.h"
  32 #include "path-util.h"
  33
  34 static const char *arg_dest = "/tmp";
  35
  36 static int add_symlink(const char *fservice, const char *tservice) {
  37         _cleanup_free_ char *from = NULL, *to = NULL;
  38         int r;
  39
  40         assert(fservice);
  41         assert(tservice);
  42
  43         from = strappend(SYSTEM_DATA_UNIT_PATH "/", fservice);
  44         if (!from)
  45                 return log_oom();
  46
  47         to = strjoin(arg_dest,"/getty.target.wants/", tservice, NULL);
  48         if (!to)
  49                 return log_oom();
  50
  51         mkdir_parents_label(to, 0755);
  52
  53         r = symlink(from, to);
  54         if (r < 0) {
  55                 if (errno == EEXIST)
  56                         /* In case console=hvc0 is passed this will very likely result in EEXIST */
  57                         return 0;
  58                 else {
  59                         log_error("Failed to create symlink %s: %m", to);
  60                         return -errno;
  61                 }
  62         }
  63
  64         return 0;
  65 }
  66
  67 static int add_serial_getty(const char *tty) {
  68         _cleanup_free_ char *n = NULL;
  69
  70         assert(tty);
  71
  72         log_debug("Automatically adding serial getty for /dev/%s.", tty);
  73
  74         n = unit_name_replace_instance("serial-getty@.service", tty);
  75         if (!n)
  76                 return log_oom();
  77
  78         return add_symlink("serial-getty@.service", n);
  79 }
  80
  81 static int add_container_getty(const char *tty) {
  82         _cleanup_free_ char *n = NULL;
  83
  84         assert(tty);
  85
  86         log_debug("Automatically adding container getty for /dev/pts/%s.", tty);
  87
  88         n = unit_name_replace_instance("container-getty@.service", tty);
  89         if (!n)
  90                 return log_oom();
  91
  92         return add_symlink("container-getty@.service", n);
  93 }
  94
  95 int main(int argc, char *argv[]) {
  96
  97         static const char virtualization_consoles[] =
  98                 "hvc0\0"
  99                 "xvc0\0"
 100                 "hvsi0\0"
 101                 "sclp_line0\0"
 102                 "ttysclp0\0";
 103
 104         _cleanup_free_ char *active = NULL;
 105         const char *j;
 106         int r;
 107
 108         if (argc > 1 && argc != 4) {
 109                 log_error("This program takes three or no arguments.");
 110                 return EXIT_FAILURE;
 111         }
 112
 113         if (argc > 1)
 114                 arg_dest = argv[1];
 115
 116         log_set_target(LOG_TARGET_SAFE);
 117         log_parse_environment();
 118         log_open();
 119
 120         umask(0022);
 121
 122         if (detect_container(NULL) > 0) {
 123                 _cleanup_free_ char *container_ttys = NULL;
 124
 125                 log_debug("Automatically adding console shell.");
 126
 127                 if (add_symlink("console-getty.service", "console-getty.service") < 0)
 128                         return EXIT_FAILURE;
 129
 130                 /* When $container_ttys is set for PID 1, spawn
 131                  * gettys on all ptys named therein. Note that despite
 132                  * the variable name we only support ptys here. */
 133
 134                 r = getenv_for_pid(1, "container_ttys", &container_ttys);
 135                 if (r > 0) {
 136                         char *w, *state;
 137                         size_t l;
 138
 139                         FOREACH_WORD(w, l, container_ttys, state) {
 140                                 const char *t;
 141                                 char tty[l + 1];
 142
 143                                 memcpy(tty, w, l);
 144                                 tty[l] = 0;
 145
 146                                 /* First strip off /dev/ if it is specified */
 147                                 t = path_startswith(tty, "/dev/");
 148                                 if (!t)
 149                                         t = tty;
 150
 151                                 /* Then, make sure it's actually a pty */
 152                                 t = path_startswith(t, "pts/");
 153                                 if (!t)
 154                                         continue;
 155
 156                                 if (add_container_getty(t) < 0)
 157                                         return EXIT_FAILURE;
 158                         }
 159                 }
 160
 161                 /* Don't add any further magic if we are in a container */
 162                 return EXIT_SUCCESS;
 163         }
 164
 165         if (read_one_line_file("/sys/class/tty/console/active", &active) >= 0) {
 166                 char *w, *state;
 167                 size_t l;
 168
 169                 /* Automatically add in a serial getty on all active
 170                  * kernel consoles */
 171                 FOREACH_WORD(w, l, active, state) {
 172                         _cleanup_free_ char *tty = NULL;
 173
 174                         tty = strndup(w, l);
 175                         if (!tty) {
 176                                 log_oom();
 177                                 return EXIT_FAILURE;
 178                         }
 179
 180                         if (isempty(tty) || tty_is_vc(tty))
 181                                 continue;
 182
 183                         /* We assume that gettys on virtual terminals are
 184                          * started via manual configuration and do this magic
 185                          * only for non-VC terminals. */
 186
 187                         if (add_serial_getty(tty) < 0)
 188                                 return EXIT_FAILURE;
 189                 }
 190         }
 191
 192         /* Automatically add in a serial getty on the first
 193          * virtualizer console */
 194         NULSTR_FOREACH(j, virtualization_consoles) {
 195                 _cleanup_free_ char *p = NULL;
 196
 197                 p = strappend("/sys/class/tty/", j);
 198                 if (!p) {
 199                         log_oom();
 200                         return EXIT_FAILURE;
 201                 }
 202
 203                 if (access(p, F_OK) < 0)
 204                         continue;
 205
 206                 if (add_serial_getty(j) < 0)
 207                         return EXIT_FAILURE;
 208         }
 209
 210         return EXIT_SUCCESS;
 211 }