src/getty-generator/getty-generator.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <string.h>
   6 #include <unistd.h>
   7
   8 #include "alloc-util.h"
   9 #include "fd-util.h"
  10 #include "fileio.h"
  11 #include "generator.h"
  12 #include "log.h"
  13 #include "mkdir.h"
  14 #include "path-util.h"
  15 #include "process-util.h"
  16 #include "strv.h"
  17 #include "terminal-util.h"
  18 #include "unit-name.h"
  19 #include "util.h"
  20 #include "virt.h"
  21
  22 static const char *arg_dest = NULL;
  23
  24 static int add_symlink(const char *fservice, const char *tservice) {
  25         char *from, *to;
  26         int r;
  27
  28         assert(fservice);
  29         assert(tservice);
  30
  31         from = strjoina(SYSTEM_DATA_UNIT_PATH "/", fservice);
  32         to = strjoina(arg_dest, "/getty.target.wants/", tservice);
  33
  34         mkdir_parents_label(to, 0755);
  35
  36         r = symlink(from, to);
  37         if (r < 0) {
  38                 /* In case console=hvc0 is passed this will very likely result in EEXIST */
  39                 if (errno == EEXIST)
  40                         return 0;
  41
  42                 return log_error_errno(errno, "Failed to create symlink %s: %m", to);
  43         }
  44
  45         return 0;
  46 }
  47
  48 static int add_serial_getty(const char *tty) {
  49         _cleanup_free_ char *n = NULL;
  50         int r;
  51
  52         assert(tty);
  53
  54         log_debug("Automatically adding serial getty for /dev/%s.", tty);
  55
  56         r = unit_name_from_path_instance("serial-getty", tty, ".service", &n);
  57         if (r < 0)
  58                 return log_error_errno(r, "Failed to generate service name: %m");
  59
  60         return add_symlink("serial-getty@.service", n);
  61 }
  62
  63 static int add_container_getty(const char *tty) {
  64         _cleanup_free_ char *n = NULL;
  65         int r;
  66
  67         assert(tty);
  68
  69         log_debug("Automatically adding container getty for /dev/pts/%s.", tty);
  70
  71         r = unit_name_from_path_instance("container-getty", tty, ".service", &n);
  72         if (r < 0)
  73                 return log_error_errno(r, "Failed to generate service name: %m");
  74
  75         return add_symlink("container-getty@.service", n);
  76 }
  77
  78 static int verify_tty(const char *name) {
  79         _cleanup_close_ int fd = -1;
  80         const char *p;
  81
  82         /* Some TTYs are weird and have been enumerated but don't work
  83          * when you try to use them, such as classic ttyS0 and
  84          * friends. Let's check that and open the device and run
  85          * isatty() on it. */
  86
  87         p = strjoina("/dev/", name);
  88
  89         /* O_NONBLOCK is essential here, to make sure we don't wait
  90          * for DCD */
  91         fd = open(p, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC|O_NOFOLLOW);
  92         if (fd < 0)
  93                 return -errno;
  94
  95         errno = 0;
  96         if (isatty(fd) <= 0)
  97                 return errno > 0 ? -errno : -EIO;
  98
  99         return 0;
 100 }
 101
 102 static int run(const char *dest, const char *dest_early, const char *dest_late) {
 103         _cleanup_free_ char *active = NULL;
 104         const char *j;
 105         int r;
 106
 107         assert_se(arg_dest = dest);
 108
 109         if (detect_container() > 0) {
 110                 _cleanup_free_ char *container_ttys = NULL;
 111
 112                 log_debug("Automatically adding console shell.");
 113
 114                 r = add_symlink("console-getty.service", "console-getty.service");
 115                 if (r < 0)
 116                         return r;
 117
 118                 /* When $container_ttys is set for PID 1, spawn
 119                  * gettys on all ptys named therein. Note that despite
 120                  * the variable name we only support ptys here. */
 121
 122                 r = getenv_for_pid(1, "container_ttys", &container_ttys);
 123                 if (r > 0) {
 124                         const char *word, *state;
 125                         size_t l;
 126
 127                         FOREACH_WORD(word, l, container_ttys, state) {
 128                                 const char *t;
 129                                 char tty[l + 1];
 130
 131                                 memcpy(tty, word, l);
 132                                 tty[l] = 0;
 133
 134                                 /* First strip off /dev/ if it is specified */
 135                                 t = path_startswith(tty, "/dev/");
 136                                 if (!t)
 137                                         t = tty;
 138
 139                                 /* Then, make sure it's actually a pty */
 140                                 t = path_startswith(t, "pts/");
 141                                 if (!t)
 142                                         continue;
 143
 144                                 r = add_container_getty(t);
 145                                 if (r < 0)
 146                                         return r;
 147                         }
 148                 }
 149
 150                 /* Don't add any further magic if we are in a container */
 151                 return 0;
 152         }
 153
 154         if (read_one_line_file("/sys/class/tty/console/active", &active) >= 0) {
 155                 const char *word, *state;
 156                 size_t l;
 157
 158                 /* Automatically add in a serial getty on all active
 159                  * kernel consoles */
 160                 FOREACH_WORD(word, l, active, state) {
 161                         _cleanup_free_ char *tty = NULL;
 162
 163                         tty = strndup(word, l);
 164                         if (!tty)
 165                                 return log_oom();
 166
 167                         /* We assume that gettys on virtual terminals are
 168                          * started via manual configuration and do this magic
 169                          * only for non-VC terminals. */
 170
 171                         if (isempty(tty) || tty_is_vc(tty))
 172                                 continue;
 173
 174                         if (verify_tty(tty) < 0)
 175                                 continue;
 176
 177                         r = add_serial_getty(tty);
 178                         if (r < 0)
 179                                 return r;
 180                 }
 181         }
 182
 183         /* Automatically add in a serial getty on the first
 184          * virtualizer console */
 185         FOREACH_STRING(j,
 186                        "hvc0",
 187                        "xvc0",
 188                        "hvsi0",
 189                        "sclp_line0",
 190                        "ttysclp0",
 191                        "3270!tty1") {
 192                 const char *p;
 193
 194                 p = strjoina("/sys/class/tty/", j);
 195                 if (access(p, F_OK) < 0)
 196                         continue;
 197
 198                 r = add_serial_getty(j);
 199                 if (r < 0)
 200                         return r;
 201         }
 202
 203         return 0;
 204 }
 205
 206 DEFINE_MAIN_GENERATOR_FUNCTION(run);