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
  28 #include "macro.h"
  29 #include "utmp-wtmp.h"
  30
  31 int utmp_get_runlevel(int *runlevel, int *previous) {
  32         struct utmpx lookup, *found;
  33         int r;
  34         const char *e;
  35
  36         assert(runlevel);
  37
  38         /* If these values are set in the environment this takes
  39          * precedence. Presumably, sysvinit does this to work around a
  40          * race condition that would otherwise exist where we'd always
  41          * go to disk and hence might read runlevel data that might be
  42          * very new and does not apply to the current script being
  43          * executed. */
  44
  45         if ((e = getenv("RUNLEVEL")) && e[0] > 0) {
  46                 *runlevel = e[0];
  47
  48                 if (previous) {
  49                         /* $PREVLEVEL seems to be an Upstart thing */
  50
  51                         if ((e = getenv("PREVLEVEL")) && e[0] > 0)
  52                                 *previous = e[0];
  53                         else
  54                                 *previous = 0;
  55                 }
  56
  57                 return 0;
  58         }
  59
  60         if (utmpxname(_PATH_UTMPX) < 0)
  61                 return -errno;
  62
  63         setutxent();
  64
  65         zero(lookup);
  66         lookup.ut_type = RUN_LVL;
  67
  68         if (!(found = getutxid(&lookup)))
  69                 r = -errno;
  70         else {
  71                 int a, b;
  72
  73                 a = found->ut_pid & 0xFF;
  74                 b = (found->ut_pid >> 8) & 0xFF;
  75
  76                 if (a < 0 || b < 0)
  77                         r = -EIO;
  78                 else {
  79                         *runlevel = a;
  80
  81                         if (previous)
  82                                 *previous = b;
  83                         r = 0;
  84                 }
  85         }
  86
  87         endutxent();
  88
  89         return r;
  90 }
  91
  92 static void init_entry(struct utmpx *store, usec_t timestamp) {
  93         struct utsname uts;
  94
  95         assert(store);
  96
  97         zero(*store);
  98         zero(uts);
  99
 100         if (timestamp <= 0)
 101                 timestamp = now(CLOCK_REALTIME);
 102
 103         store->ut_tv.tv_sec = timestamp / USEC_PER_SEC;
 104         store->ut_tv.tv_usec = timestamp % USEC_PER_SEC;
 105
 106         if (uname(&uts) >= 0)
 107                 strncpy(store->ut_host, uts.release, sizeof(store->ut_host));
 108
 109         strncpy(store->ut_line, "~", sizeof(store->ut_line));  /* or ~~ ? */
 110         strncpy(store->ut_id, "~~", sizeof(store->ut_id));
 111 }
 112
 113 static int write_entry_utmp(const struct utmpx *store) {
 114         int r;
 115
 116         assert(store);
 117
 118         /* utmp is similar to wtmp, but there is only one entry for
 119          * each entry type resp. user; i.e. basically a key/value
 120          * table. */
 121
 122         if (utmpxname(_PATH_UTMPX) < 0)
 123                 return -errno;
 124
 125         setutxent();
 126
 127         if (!pututxline(store))
 128                 r = -errno;
 129         else
 130                 r = 0;
 131
 132         endutxent();
 133
 134         return r;
 135 }
 136
 137 static int write_entry_wtmp(const struct utmpx *store) {
 138         assert(store);
 139
 140         /* wtmp is a simple append-only file where each entry is
 141         simply appended to * the end; i.e. basically a log. */
 142
 143         errno = 0;
 144         updwtmpx(_PATH_WTMPX, store);
 145         return -errno;
 146 }
 147
 148 static int write_entry_both(const struct utmpx *store) {
 149         int r, s;
 150
 151         r = write_entry_utmp(store);
 152         s = write_entry_wtmp(store);
 153
 154         if (r >= 0)
 155                 r = s;
 156
 157         /* If utmp/wtmp have been disabled, that's a good thing, hence
 158          * ignore the errors */
 159         if (r == -ENOENT)
 160                 r = 0;
 161
 162         return r;
 163 }
 164
 165 int utmp_put_shutdown(usec_t timestamp) {
 166         struct utmpx store;
 167
 168         init_entry(&store, timestamp);
 169
 170         store.ut_type = RUN_LVL;
 171         strncpy(store.ut_user, "shutdown", sizeof(store.ut_user));
 172
 173         return write_entry_both(&store);
 174 }
 175
 176 int utmp_put_reboot(usec_t timestamp) {
 177         struct utmpx store;
 178
 179         init_entry(&store, timestamp);
 180
 181         store.ut_type = BOOT_TIME;
 182         strncpy(store.ut_user, "reboot", sizeof(store.ut_type));
 183
 184         return write_entry_both(&store);
 185 }
 186
 187 int utmp_put_runlevel(usec_t timestamp, int runlevel, int previous) {
 188         struct utmpx store;
 189         int r;
 190
 191         assert(runlevel > 0);
 192
 193         if (previous <= 0) {
 194                 /* Find the old runlevel automatically */
 195
 196                 if ((r = utmp_get_runlevel(&previous, NULL)) < 0)
 197                         return r;
 198
 199                 if (previous == runlevel)
 200                         return 0;
 201         }
 202
 203         init_entry(&store, timestamp);
 204
 205         store.ut_type = RUN_LVL;
 206         store.ut_pid = (runlevel & 0xFF) | ((previous & 0xFF) << 8);
 207         strncpy(store.ut_user, "runlevel", sizeof(store.ut_user));
 208
 209         return write_entry_both(&store);
 210 }