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 #include <fcntl.h>
  26
  27 #include "log.h"
  28 #include "util.h"
  29 #include "mkdir.h"
  30 #include "unit-name.h"
  31 #include "virt.h"
  32 #include "fileio.h"
  33 #include "path-util.h"
  34 #include "process-util.h"
  35
  36 static const char *arg_dest = "/tmp";
  37
  38 static int add_symlink(const char *fservice, const char *tservice) {
  39         char *from, *to;
  40         int r;
  41
  42         assert(fservice);
  43         assert(tservice);
  44
  45         from = strjoina(SYSTEM_DATA_UNIT_PATH "/", fservice);
  46         to = strjoina(arg_dest, "/getty.target.wants/", tservice);
  47
  48         mkdir_parents_label(to, 0755);
  49
  50         r = symlink(from, to);
  51         if (r < 0) {
  52                 if (errno == EEXIST)
  53                         /* In case console=hvc0 is passed this will very likely result in EEXIST */
  54                         return 0;
  55                 else {
  56                         log_error_errno(errno, "Failed to create symlink %s: %m", to);
  57                         return -errno;
  58                 }
  59         }
  60
  61         return 0;
  62 }
  63
  64 static int add_serial_getty(const char *tty) {
  65         _cleanup_free_ char *n = NULL;
  66
  67         assert(tty);
  68
  69         log_debug("Automatically adding serial getty for /dev/%s.", tty);
  70
  71         n = unit_name_from_path_instance("serial-getty", tty, ".service");
  72         if (!n)
  73                 return log_oom();
  74
  75         return add_symlink("serial-getty@.service", n);
  76 }
  77
  78 static int add_container_getty(const char *tty) {
  79         _cleanup_free_ char *n = NULL;
  80
  81         assert(tty);
  82
  83         log_debug("Automatically adding container getty for /dev/pts/%s.", tty);
  84
  85         n = unit_name_from_path_instance("container-getty", tty, ".service");
  86         if (!n)
  87                 return log_oom();
  88
  89         return add_symlink("container-getty@.service", n);
  90 }
  91
  92 static int verify_tty(const char *name) {
  93         _cleanup_close_ int fd = -1;
  94         const char *p;
  95
  96         /* Some TTYs are weird and have been enumerated but don't work
  97          * when you try to use them, such as classic ttyS0 and
  98          * friends. Let's check that and open the device and run
  99          * isatty() on it. */
 100
 101         p = strjoina("/dev/", name);
 102
 103         /* O_NONBLOCK is essential here, to make sure we don't wait
 104          * for DCD */
 105         fd = open(p, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC|O_NOFOLLOW);
 106         if (fd < 0)
 107                 return -errno;
 108
 109         errno = 0;
 110         if (isatty(fd) <= 0)
 111                 return errno ? -errno : -EIO;
 112
 113         return 0;
 114 }
 115
 116 int main(int argc, char *argv[]) {
 117
 118         static const char virtualization_consoles[] =
 119                 "hvc0\0"
 120                 "xvc0\0"
 121                 "hvsi0\0"
 122                 "sclp_line0\0"
 123                 "ttysclp0\0"
 124                 "3270!tty1\0";
 125
 126         _cleanup_free_ char *active = NULL;
 127         const char *j;
 128         int r;
 129
 130         if (argc > 1 && argc != 4) {
 131                 log_error("This program takes three or no arguments.");
 132                 return EXIT_FAILURE;
 133         }
 134
 135         if (argc > 1)
 136                 arg_dest = argv[1];
 137
 138         log_set_target(LOG_TARGET_SAFE);
 139         log_parse_environment();
 140         log_open();
 141
 142         umask(0022);
 143
 144         if (detect_container(NULL) > 0) {
 145                 _cleanup_free_ char *container_ttys = NULL;
 146
 147                 log_debug("Automatically adding console shell.");
 148
 149                 if (add_symlink("console-getty.service", "console-getty.service") < 0)
 150                         return EXIT_FAILURE;
 151
 152                 /* When $container_ttys is set for PID 1, spawn
 153                  * gettys on all ptys named therein. Note that despite
 154                  * the variable name we only support ptys here. */
 155
 156                 r = getenv_for_pid(1, "container_ttys", &container_ttys);
 157                 if (r > 0) {
 158                         const char *word, *state;
 159                         size_t l;
 160
 161                         FOREACH_WORD(word, l, container_ttys, state) {
 162                                 const char *t;
 163                                 char tty[l + 1];
 164
 165                                 memcpy(tty, word, l);
 166                                 tty[l] = 0;
 167
 168                                 /* First strip off /dev/ if it is specified */
 169                                 t = path_startswith(tty, "/dev/");
 170                                 if (!t)
 171                                         t = tty;
 172
 173                                 /* Then, make sure it's actually a pty */
 174                                 t = path_startswith(t, "pts/");
 175                                 if (!t)
 176                                         continue;
 177
 178                                 if (add_container_getty(t) < 0)
 179                                         return EXIT_FAILURE;
 180                         }
 181                 }
 182
 183                 /* Don't add any further magic if we are in a container */
 184                 return EXIT_SUCCESS;
 185         }
 186
 187         if (read_one_line_file("/sys/class/tty/console/active", &active) >= 0) {
 188                 const char *word, *state;
 189                 size_t l;
 190
 191                 /* Automatically add in a serial getty on all active
 192                  * kernel consoles */
 193                 FOREACH_WORD(word, l, active, state) {
 194                         _cleanup_free_ char *tty = NULL;
 195
 196                         tty = strndup(word, l);
 197                         if (!tty) {
 198                                 log_oom();
 199                                 return EXIT_FAILURE;
 200                         }
 201
 202                         if (isempty(tty) || tty_is_vc(tty))
 203                                 continue;
 204
 205                         if (verify_tty(tty) < 0)
 206                                 continue;
 207
 208                         /* We assume that gettys on virtual terminals are
 209                          * started via manual configuration and do this magic
 210                          * only for non-VC terminals. */
 211
 212                         if (add_serial_getty(tty) < 0)
 213                                 return EXIT_FAILURE;
 214                 }
 215         }
 216
 217         /* Automatically add in a serial getty on the first
 218          * virtualizer console */
 219         NULSTR_FOREACH(j, virtualization_consoles) {
 220                 char *p;
 221
 222                 p = strjoina("/sys/class/tty/", j);
 223                 if (access(p, F_OK) < 0)
 224                         continue;
 225
 226                 if (add_serial_getty(j) < 0)
 227                         return EXIT_FAILURE;
 228         }
 229
 230         return EXIT_SUCCESS;
 231 }