src/utmp-wtmp.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 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_timestamp(struct utmpx *store, usec_t t) {
  96         assert(store);
  97
  98         zero(*store);
  99
 100         if (t <= 0)
 101                 t = now(CLOCK_REALTIME);
 102
 103         store->ut_tv.tv_sec = t / USEC_PER_SEC;
 104         store->ut_tv.tv_usec = t % USEC_PER_SEC;
 105 }
 106
 107 static void init_entry(struct utmpx *store, usec_t t) {
 108         struct utsname uts;
 109
 110         assert(store);
 111
 112         init_timestamp(store, t);
 113
 114         zero(uts);
 115
 116         if (uname(&uts) >= 0)
 117                 strncpy(store->ut_host, uts.release, sizeof(store->ut_host));
 118
 119         strncpy(store->ut_line, "~", sizeof(store->ut_line));  /* or ~~ ? */
 120         strncpy(store->ut_id, "~~", sizeof(store->ut_id));
 121 }
 122
 123 static int write_entry_utmp(const struct utmpx *store) {
 124         int r;
 125
 126         assert(store);
 127
 128         /* utmp is similar to wtmp, but there is only one entry for
 129          * each entry type resp. user; i.e. basically a key/value
 130          * table. */
 131
 132         if (utmpxname(_PATH_UTMPX) < 0)
 133                 return -errno;
 134
 135         setutxent();
 136
 137         if (!pututxline(store))
 138                 r = -errno;
 139         else
 140                 r = 0;
 141
 142         endutxent();
 143
 144         return r;
 145 }
 146
 147 static int write_entry_wtmp(const struct utmpx *store) {
 148         assert(store);
 149
 150         /* wtmp is a simple append-only file where each entry is
 151         simply appended to * the end; i.e. basically a log. */
 152
 153         errno = 0;
 154         updwtmpx(_PATH_WTMPX, store);
 155         return -errno;
 156 }
 157
 158 static int write_entry_both(const struct utmpx *store) {
 159         int r, s;
 160
 161         r = write_entry_utmp(store);
 162         s = write_entry_wtmp(store);
 163
 164         if (r >= 0)
 165                 r = s;
 166
 167         /* If utmp/wtmp have been disabled, that's a good thing, hence
 168          * ignore the errors */
 169         if (r == -ENOENT)
 170                 r = 0;
 171
 172         return r;
 173 }
 174
 175 int utmp_put_shutdown(void) {
 176         struct utmpx store;
 177
 178         init_entry(&store, 0);
 179
 180         store.ut_type = RUN_LVL;
 181         strncpy(store.ut_user, "shutdown", sizeof(store.ut_user));
 182
 183         return write_entry_both(&store);
 184 }
 185
 186 int utmp_put_reboot(usec_t t) {
 187         struct utmpx store;
 188
 189         init_entry(&store, t);
 190
 191         store.ut_type = BOOT_TIME;
 192         strncpy(store.ut_user, "reboot", sizeof(store.ut_user));
 193
 194         return write_entry_both(&store);
 195 }
 196
 197 static const char *sanitize_id(const char *id) {
 198         size_t l;
 199
 200         assert(id);
 201         l = strlen(id);
 202
 203         if (l <= sizeof(((struct utmpx*) NULL)->ut_id))
 204                 return id;
 205
 206         return id + l - sizeof(((struct utmpx*) NULL)->ut_id);
 207 }
 208
 209 int utmp_put_init_process(const char *id, pid_t pid, pid_t sid, const char *line) {
 210         struct utmpx store;
 211
 212         assert(id);
 213
 214         init_timestamp(&store, 0);
 215
 216         store.ut_type = INIT_PROCESS;
 217         store.ut_pid = pid;
 218         store.ut_session = sid;
 219
 220         strncpy(store.ut_id, sanitize_id(id), sizeof(store.ut_id));
 221
 222         if (line)
 223                 strncpy(store.ut_line, file_name_from_path(line), sizeof(store.ut_line));
 224
 225         return write_entry_both(&store);
 226 }
 227
 228 int utmp_put_dead_process(const char *id, pid_t pid, int code, int status) {
 229         struct utmpx lookup, store, *found;
 230
 231         assert(id);
 232
 233         setutxent();
 234
 235         zero(lookup);
 236         lookup.ut_type = INIT_PROCESS; /* looks for DEAD_PROCESS, LOGIN_PROCESS, USER_PROCESS, too */
 237         strncpy(lookup.ut_id, sanitize_id(id), sizeof(lookup.ut_id));
 238
 239         if (!(found = getutxid(&lookup)))
 240                 return 0;
 241
 242         if (found->ut_pid != pid)
 243                 return 0;
 244
 245         zero(store);
 246
 247         memcpy(&store, &lookup, sizeof(store));
 248         store.ut_type = DEAD_PROCESS;
 249         store.ut_exit.e_termination = code;
 250         store.ut_exit.e_exit = status;
 251
 252         zero(store.ut_user);
 253         zero(store.ut_host);
 254         zero(store.ut_tv);
 255
 256         return write_entry_both(&store);
 257 }
 258
 259
 260 int utmp_put_runlevel(int runlevel, int previous) {
 261         struct utmpx store;
 262         int r;
 263
 264         assert(runlevel > 0);
 265
 266         if (previous <= 0) {
 267                 /* Find the old runlevel automatically */
 268
 269                 if ((r = utmp_get_runlevel(&previous, NULL)) < 0) {
 270                         if (r != -ESRCH)
 271                                 return r;
 272
 273                         previous = 0;
 274                 }
 275         }
 276
 277         if (previous == runlevel)
 278                 return 0;
 279
 280         init_entry(&store, 0);
 281
 282         store.ut_type = RUN_LVL;
 283         store.ut_pid = (runlevel & 0xFF) | ((previous & 0xFF) << 8);
 284         strncpy(store.ut_user, "runlevel", sizeof(store.ut_user));
 285
 286         return write_entry_both(&store);
 287 }
 288
 289 #define TIMEOUT_MSEC 50
 290
 291 static int write_to_terminal(const char *tty, const char *message) {
 292         int fd, r;
 293         const char *p;
 294         size_t left;
 295         usec_t end;
 296
 297         assert(tty);
 298         assert(message);
 299
 300         if ((fd = open(tty, O_WRONLY|O_NDELAY|O_NOCTTY|O_CLOEXEC)) < 0)
 301                 return -errno;
 302
 303         if (!isatty(fd)) {
 304                 r = -errno;
 305                 goto finish;
 306         }
 307
 308         p = message;
 309         left = strlen(message);
 310
 311         end = now(CLOCK_MONOTONIC) + TIMEOUT_MSEC*USEC_PER_MSEC;
 312
 313         while (left > 0) {
 314                 ssize_t n;
 315                 struct pollfd pollfd;
 316                 usec_t t;
 317                 int k;
 318
 319                 t = now(CLOCK_MONOTONIC);
 320
 321                 if (t >= end) {
 322                         r = -ETIME;
 323                         goto finish;
 324                 }
 325
 326                 zero(pollfd);
 327                 pollfd.fd = fd;
 328                 pollfd.events = POLLOUT;
 329
 330                 if ((k = poll(&pollfd, 1, (end - t) / USEC_PER_MSEC)) < 0)
 331                         return -errno;
 332
 333                 if (k <= 0) {
 334                         r = -ETIME;
 335                         goto finish;
 336                 }
 337
 338                 if ((n = write(fd, p, left)) < 0) {
 339
 340                         if (errno == EAGAIN)
 341                                 continue;
 342
 343                         r = -errno;
 344                         goto finish;
 345                 }
 346
 347                 assert((size_t) n <= left);
 348
 349                 p += n;
 350                 left -= n;
 351         }
 352
 353         r = 0;
 354
 355 finish:
 356         close_nointr_nofail(fd);
 357
 358         return r;
 359 }
 360
 361 int utmp_wall(const char *message, bool (*match_tty)(const char *tty)) {
 362         struct utmpx *u;
 363         char date[FORMAT_TIMESTAMP_MAX];
 364         char *text = NULL, *hn = NULL, *un = NULL, *tty = NULL;
 365         int r;
 366
 367         if (!(hn = gethostname_malloc()) ||
 368             !(un = getlogname_malloc())) {
 369                 r = -ENOMEM;
 370                 goto finish;
 371         }
 372
 373         getttyname_harder(STDIN_FILENO, &tty);
 374
 375         if (asprintf(&text,
 376                      "\a\r\n"
 377                      "Broadcast message from %s@%s%s%s (%s):\r\n\r\n"
 378                      "%s\r\n\r\n",
 379                      un, hn,
 380                      tty ? " on " : "", strempty(tty),
 381                      format_timestamp(date, sizeof(date), now(CLOCK_REALTIME)),
 382                      message) < 0) {
 383                 r = -ENOMEM;
 384                 goto finish;
 385         }
 386
 387         setutxent();
 388
 389         r = 0;
 390
 391         while ((u = getutxent())) {
 392                 int q;
 393                 const char *path;
 394                 char *buf = NULL;
 395
 396                 if (u->ut_type != USER_PROCESS || u->ut_user[0] == 0)
 397                         continue;
 398
 399                 if (path_startswith(u->ut_line, "/dev/"))
 400                         path = u->ut_line;
 401                 else {
 402                         if (asprintf(&buf, "/dev/%s", u->ut_line) < 0) {
 403                                 r = -ENOMEM;
 404                                 goto finish;
 405                         }
 406
 407                         path = buf;
 408                 }
 409
 410                 if (!match_tty || match_tty(path))
 411                         if ((q = write_to_terminal(path, text)) < 0)
 412                                 r = q;
 413
 414                 free(buf);
 415         }
 416
 417 finish:
 418         free(hn);
 419         free(un);
 420         free(tty);
 421         free(text);
 422
 423         return r;
 424 }