src/getty-generator/getty-generator.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   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 <fcntl.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24
  25 #include "alloc-util.h"
  26 #include "fd-util.h"
  27 #include "fileio.h"
  28 #include "log.h"
  29 #include "mkdir.h"
  30 #include "path-util.h"
  31 #include "process-util.h"
  32 #include "string-util.h"
  33 #include "terminal-util.h"
  34 #include "unit-name.h"
  35 #include "util.h"
  36 #include "virt.h"
  37
  38 static const char *arg_dest = "/tmp";
  39
  40 static int add_symlink(const char *fservice, const char *tservice) {
  41         char *from, *to;
  42         int r;
  43
  44         assert(fservice);
  45         assert(tservice);
  46
  47         from = strjoina(SYSTEM_DATA_UNIT_PATH "/", fservice);
  48         to = strjoina(arg_dest, "/getty.target.wants/", tservice);
  49
  50         mkdir_parents_label(to, 0755);
  51
  52         r = symlink(from, to);
  53         if (r < 0) {
  54                 /* In case console=hvc0 is passed this will very likely result in EEXIST */
  55                 if (errno == EEXIST)
  56                         return 0;
  57
  58                 return log_error_errno(errno, "Failed to create symlink %s: %m", to);
  59         }
  60
  61         return 0;
  62 }
  63
  64 static int add_serial_getty(const char *tty) {
  65         _cleanup_free_ char *n = NULL;
  66         int r;
  67
  68         assert(tty);
  69
  70         log_debug("Automatically adding serial getty for /dev/%s.", tty);
  71
  72         r = unit_name_from_path_instance("serial-getty", tty, ".service", &n);
  73         if (r < 0)
  74                 return log_error_errno(r, "Failed to generate service name: %m");
  75
  76         return add_symlink("serial-getty@.service", n);
  77 }
  78
  79 static int add_container_getty(const char *tty) {
  80         _cleanup_free_ char *n = NULL;
  81         int r;
  82
  83         assert(tty);
  84
  85         log_debug("Automatically adding container getty for /dev/pts/%s.", tty);
  86
  87         r = unit_name_from_path_instance("container-getty", tty, ".service", &n);
  88         if (r < 0)
  89                 return log_error_errno(r, "Failed to generate service name: %m");
  90
  91         return add_symlink("container-getty@.service", n);
  92 }
  93
  94 static int verify_tty(const char *name) {
  95         _cleanup_close_ int fd = -1;
  96         const char *p;
  97
  98         /* Some TTYs are weird and have been enumerated but don't work
  99          * when you try to use them, such as classic ttyS0 and
 100          * friends. Let's check that and open the device and run
 101          * isatty() on it. */
 102
 103         p = strjoina("/dev/", name);
 104
 105         /* O_NONBLOCK is essential here, to make sure we don't wait
 106          * for DCD */
 107         fd = open(p, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC|O_NOFOLLOW);
 108         if (fd < 0)
 109                 return -errno;
 110
 111         errno = 0;
 112         if (isatty(fd) <= 0)
 113                 return errno > 0 ? -errno : -EIO;
 114
 115         return 0;
 116 }
 117
 118 int main(int argc, char *argv[]) {
 119
 120         static const char virtualization_consoles[] =
 121                 "hvc0\0"
 122                 "xvc0\0"
 123                 "hvsi0\0"
 124                 "sclp_line0\0"
 125                 "ttysclp0\0"
 126                 "3270!tty1\0";
 127
 128         _cleanup_free_ char *active = NULL;
 129         const char *j;
 130         int r;
 131
 132         if (argc > 1 && argc != 4) {
 133                 log_error("This program takes three or no arguments.");
 134                 return EXIT_FAILURE;
 135         }
 136
 137         if (argc > 1)
 138                 arg_dest = argv[1];
 139
 140         log_set_target(LOG_TARGET_SAFE);
 141         log_parse_environment();
 142         log_open();
 143
 144         umask(0022);
 145
 146         if (detect_container() > 0) {
 147                 _cleanup_free_ char *container_ttys = NULL;
 148
 149                 log_debug("Automatically adding console shell.");
 150
 151                 if (add_symlink("console-getty.service", "console-getty.service") < 0)
 152                         return EXIT_FAILURE;
 153
 154                 /* When $container_ttys is set for PID 1, spawn
 155                  * gettys on all ptys named therein. Note that despite
 156                  * the variable name we only support ptys here. */
 157
 158                 r = getenv_for_pid(1, "container_ttys", &container_ttys);
 159                 if (r > 0) {
 160                         const char *word, *state;
 161                         size_t l;
 162
 163                         FOREACH_WORD(word, l, container_ttys, state) {
 164                                 const char *t;
 165                                 char tty[l + 1];
 166
 167                                 memcpy(tty, word, l);
 168                                 tty[l] = 0;
 169
 170                                 /* First strip off /dev/ if it is specified */
 171                                 t = path_startswith(tty, "/dev/");
 172                                 if (!t)
 173                                         t = tty;
 174
 175                                 /* Then, make sure it's actually a pty */
 176                                 t = path_startswith(t, "pts/");
 177                                 if (!t)
 178                                         continue;
 179
 180                                 if (add_container_getty(t) < 0)
 181                                         return EXIT_FAILURE;
 182                         }
 183                 }
 184
 185                 /* Don't add any further magic if we are in a container */
 186                 return EXIT_SUCCESS;
 187         }
 188
 189         if (read_one_line_file("/sys/class/tty/console/active", &active) >= 0) {
 190                 const char *word, *state;
 191                 size_t l;
 192
 193                 /* Automatically add in a serial getty on all active
 194                  * kernel consoles */
 195                 FOREACH_WORD(word, l, active, state) {
 196                         _cleanup_free_ char *tty = NULL;
 197
 198                         tty = strndup(word, l);
 199                         if (!tty) {
 200                                 log_oom();
 201                                 return EXIT_FAILURE;
 202                         }
 203
 204                         if (isempty(tty) || tty_is_vc(tty))
 205                                 continue;
 206
 207                         if (verify_tty(tty) < 0)
 208                                 continue;
 209
 210                         /* We assume that gettys on virtual terminals are
 211                          * started via manual configuration and do this magic
 212                          * only for non-VC terminals. */
 213
 214                         if (add_serial_getty(tty) < 0)
 215                                 return EXIT_FAILURE;
 216                 }
 217         }
 218
 219         /* Automatically add in a serial getty on the first
 220          * virtualizer console */
 221         NULSTR_FOREACH(j, virtualization_consoles) {
 222                 char *p;
 223
 224                 p = strjoina("/sys/class/tty/", j);
 225                 if (access(p, F_OK) < 0)
 226                         continue;
 227
 228                 if (add_serial_getty(j) < 0)
 229                         return EXIT_FAILURE;
 230         }
 231
 232         return EXIT_SUCCESS;
 233 }