src/utmp-wtmp.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   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 General Public License as published by
  10   the Free Software Foundation; either version 2 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   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <utmpx.h>
  23 #include <errno.h>
  24 #include <assert.h>
  25 #include <string.h>
  26 #include <sys/utsname.h>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <sys/poll.h>
  30
  31 #include "macro.h"
  32 #include "utmp-wtmp.h"
  33
  34 int utmp_get_runlevel(int *runlevel, int *previous) {
  35         struct utmpx lookup, *found;
  36         int r;
  37         const char *e;
  38
  39         assert(runlevel);
  40
  41         /* If these values are set in the environment this takes
  42          * precedence. Presumably, sysvinit does this to work around a
  43          * race condition that would otherwise exist where we'd always
  44          * go to disk and hence might read runlevel data that might be
  45          * very new and does not apply to the current script being
  46          * executed. */
  47
  48         if ((e = getenv("RUNLEVEL")) && e[0] > 0) {
  49                 *runlevel = e[0];
  50
  51                 if (previous) {
  52                         /* $PREVLEVEL seems to be an Upstart thing */
  53
  54                         if ((e = getenv("PREVLEVEL")) && e[0] > 0)
  55                                 *previous = e[0];
  56                         else
  57                                 *previous = 0;
  58                 }
  59
  60                 return 0;
  61         }
  62
  63         if (utmpxname(_PATH_UTMPX) < 0)
  64                 return -errno;
  65
  66         setutxent();
  67
  68         zero(lookup);
  69         lookup.ut_type = RUN_LVL;
  70
  71         if (!(found = getutxid(&lookup)))
  72                 r = -errno;
  73         else {
  74                 int a, b;
  75
  76                 a = found->ut_pid & 0xFF;
  77                 b = (found->ut_pid >> 8) & 0xFF;
  78
  79                 if (a < 0 || b < 0)
  80                         r = -EIO;
  81                 else {
  82                         *runlevel = a;
  83
  84                         if (previous)
  85                                 *previous = b;
  86                         r = 0;
  87                 }
  88         }
  89
  90         endutxent();
  91
  92         return r;
  93 }
  94
  95 static void init_entry(struct utmpx *store, usec_t t) {
  96         struct utsname uts;
  97
  98         assert(store);
  99
 100         zero(*store);
 101         zero(uts);
 102
 103         if (t <= 0)
 104                 t = now(CLOCK_REALTIME);
 105
 106         store->ut_tv.tv_sec = t / USEC_PER_SEC;
 107         store->ut_tv.tv_usec = t % USEC_PER_SEC;
 108
 109         if (uname(&uts) >= 0)
 110                 strncpy(store->ut_host, uts.release, sizeof(store->ut_host));
 111
 112         strncpy(store->ut_line, "~", sizeof(store->ut_line));  /* or ~~ ? */
 113         strncpy(store->ut_id, "~~", sizeof(store->ut_id));
 114 }
 115
 116 static int write_entry_utmp(const struct utmpx *store) {
 117         int r;
 118
 119         assert(store);
 120
 121         /* utmp is similar to wtmp, but there is only one entry for
 122          * each entry type resp. user; i.e. basically a key/value
 123          * table. */
 124
 125         if (utmpxname(_PATH_UTMPX) < 0)
 126                 return -errno;
 127
 128         setutxent();
 129
 130         if (!pututxline(store))
 131                 r = -errno;
 132         else
 133                 r = 0;
 134
 135         endutxent();
 136
 137         return r;
 138 }
 139
 140 static int write_entry_wtmp(const struct utmpx *store) {
 141         assert(store);
 142
 143         /* wtmp is a simple append-only file where each entry is
 144         simply appended to * the end; i.e. basically a log. */
 145
 146         errno = 0;
 147         updwtmpx(_PATH_WTMPX, store);
 148         return -errno;
 149 }
 150
 151 static int write_entry_both(const struct utmpx *store) {
 152         int r, s;
 153
 154         r = write_entry_utmp(store);
 155         s = write_entry_wtmp(store);
 156
 157         if (r >= 0)
 158                 r = s;
 159
 160         /* If utmp/wtmp have been disabled, that's a good thing, hence
 161          * ignore the errors */
 162         if (r == -ENOENT)
 163                 r = 0;
 164
 165         return r;
 166 }
 167
 168 int utmp_put_shutdown(usec_t t) {
 169         struct utmpx store;
 170
 171         init_entry(&store, t);
 172
 173         store.ut_type = RUN_LVL;
 174         strncpy(store.ut_user, "shutdown", sizeof(store.ut_user));
 175
 176         return write_entry_both(&store);
 177 }
 178
 179 int utmp_put_reboot(usec_t t) {
 180         struct utmpx store;
 181
 182         init_entry(&store, t);
 183
 184         store.ut_type = BOOT_TIME;
 185         strncpy(store.ut_user, "reboot", sizeof(store.ut_user));
 186
 187         return write_entry_both(&store);
 188 }
 189
 190 int utmp_put_runlevel(usec_t t, int runlevel, int previous) {
 191         struct utmpx store;
 192         int r;
 193
 194         assert(runlevel > 0);
 195
 196         if (previous <= 0) {
 197                 /* Find the old runlevel automatically */
 198
 199                 if ((r = utmp_get_runlevel(&previous, NULL)) < 0) {
 200                         if (r != -ESRCH)
 201                                 return r;
 202
 203                         previous = 0;
 204                 }
 205
 206                 if (previous == runlevel)
 207                         return 0;
 208         }
 209
 210         init_entry(&store, t);
 211
 212         store.ut_type = RUN_LVL;
 213         store.ut_pid = (runlevel & 0xFF) | ((previous & 0xFF) << 8);
 214         strncpy(store.ut_user, "runlevel", sizeof(store.ut_user));
 215
 216         return write_entry_both(&store);
 217 }
 218
 219 #define TIMEOUT_MSEC 50
 220
 221 static int write_to_terminal(const char *tty, const char *message) {
 222         int fd, r;
 223         const char *p;
 224         size_t left;
 225         usec_t end;
 226
 227         assert(tty);
 228         assert(message);
 229
 230         if ((fd = open(tty, O_WRONLY|O_NDELAY|O_NOCTTY|O_CLOEXEC)) < 0)
 231                 return -errno;
 232
 233         if (!isatty(fd)) {
 234                 r = -errno;
 235                 goto finish;
 236         }
 237
 238         p = message;
 239         left = strlen(message);
 240
 241         end = now(CLOCK_MONOTONIC) + TIMEOUT_MSEC*USEC_PER_MSEC;
 242
 243         while (left > 0) {
 244                 ssize_t n;
 245                 struct pollfd pollfd;
 246                 usec_t t;
 247                 int k;
 248
 249                 t = now(CLOCK_MONOTONIC);
 250
 251                 if (t >= end) {
 252                         r = -ETIME;
 253                         goto finish;
 254                 }
 255
 256                 zero(pollfd);
 257                 pollfd.fd = fd;
 258                 pollfd.events = POLLOUT;
 259
 260                 if ((k = poll(&pollfd, 1, (end - t) / USEC_PER_MSEC)) < 0)
 261                         return -errno;
 262
 263                 if (k <= 0) {
 264                         r = -ETIME;
 265                         goto finish;
 266                 }
 267
 268                 if ((n = write(fd, p, left)) < 0) {
 269
 270                         if (errno == EAGAIN)
 271                                 continue;
 272
 273                         r = -errno;
 274                         goto finish;
 275                 }
 276
 277                 assert((size_t) n <= left);
 278
 279                 p += n;
 280                 left -= n;
 281         }
 282
 283         r = 0;
 284
 285 finish:
 286         close_nointr_nofail(fd);
 287
 288         return r;
 289 }
 290
 291 int utmp_wall(const char *message) {
 292         struct utmpx *u;
 293         char date[26];
 294         char *text = NULL, *hn = NULL, *un = NULL, *tty = NULL;
 295         int r;
 296         time_t t;
 297
 298         if (!(hn = gethostname_malloc()) ||
 299             !(un = getlogname_malloc())) {
 300                 r = -ENOMEM;
 301                 goto finish;
 302         }
 303
 304         if ((r = getttyname_malloc(&tty)) < 0)
 305                 goto finish;
 306
 307         time(&t);
 308         assert_se(ctime_r(&t, date));
 309         delete_chars(date, "\n\r");
 310
 311         if (asprintf(&text,
 312                      "\a\r\n"
 313                      "Broadcast message from %s@%s on %s (%s):\r\n\r\n"
 314                      "%s\r\n\r\n",
 315                      un, hn, tty, date, message) < 0) {
 316                 r = -ENOMEM;
 317                 goto finish;
 318         }
 319
 320         setutxent();
 321
 322         r = 0;
 323
 324         while ((u = getutxent())) {
 325                 int q;
 326                 const char *path;
 327                 char *buf = NULL;
 328
 329                 if (u->ut_type != USER_PROCESS || u->ut_user[0] == 0)
 330                         continue;
 331
 332                 if (path_startswith(u->ut_line, "/dev/"))
 333                         path = u->ut_line;
 334                 else {
 335                         if (asprintf(&buf, "/dev/%s", u->ut_line) < 0) {
 336                                 r = -ENOMEM;
 337                                 goto finish;
 338                         }
 339
 340                         path = buf;
 341                 }
 342
 343                 if ((q = write_to_terminal(path, text)) < 0)
 344                         r = q;
 345
 346                 free(buf);
 347         }
 348
 349 finish:
 350         free(hn);
 351         free(un);
 352         free(tty);
 353         free(text);
 354
 355         return r;
 356 }