utmp-wtmp.c revision f33d3ec1d7521c91da8b30ad5cb345d6416bb07d
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <utmpx.h>
#include <errno.h>
#include <assert.h>
#include <string.h>
#include <sys/utsname.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/poll.h>
#include "macro.h"
#include "utmp-wtmp.h"
int utmp_get_runlevel(int *runlevel, int *previous) {
struct utmpx lookup, *found;
int r;
const char *e;
assert(runlevel);
/* If these values are set in the environment this takes
* precedence. Presumably, sysvinit does this to work around a
* race condition that would otherwise exist where we'd always
* go to disk and hence might read runlevel data that might be
* very new and does not apply to the current script being
* executed. */
if ((e = getenv("RUNLEVEL")) && e[0] > 0) {
*runlevel = e[0];
if (previous) {
/* $PREVLEVEL seems to be an Upstart thing */
if ((e = getenv("PREVLEVEL")) && e[0] > 0)
*previous = e[0];
else
*previous = 0;
}
return 0;
}
if (utmpxname(_PATH_UTMPX) < 0)
return -errno;
setutxent();
zero(lookup);
lookup.ut_type = RUN_LVL;
if (!(found = getutxid(&lookup)))
r = -errno;
else {
int a, b;
a = found->ut_pid & 0xFF;
b = (found->ut_pid >> 8) & 0xFF;
if (a < 0 || b < 0)
r = -EIO;
else {
*runlevel = a;
if (previous)
*previous = b;
r = 0;
}
}
endutxent();
return r;
}
static void init_timestamp(struct utmpx *store, usec_t t) {
assert(store);
zero(*store);
if (t <= 0)
t = now(CLOCK_REALTIME);
store->ut_tv.tv_sec = t / USEC_PER_SEC;
store->ut_tv.tv_usec = t % USEC_PER_SEC;
}
static void init_entry(struct utmpx *store, usec_t t) {
struct utsname uts;
assert(store);
init_timestamp(store, t);
zero(uts);
if (uname(&uts) >= 0)
strncpy(store->ut_host, uts.release, sizeof(store->ut_host));
strncpy(store->ut_line, "~", sizeof(store->ut_line)); /* or ~~ ? */
strncpy(store->ut_id, "~~", sizeof(store->ut_id));
}
static int write_entry_utmp(const struct utmpx *store) {
int r;
assert(store);
/* utmp is similar to wtmp, but there is only one entry for
* each entry type resp. user; i.e. basically a key/value
* table. */
if (utmpxname(_PATH_UTMPX) < 0)
return -errno;
setutxent();
if (!pututxline(store))
r = -errno;
else
r = 0;
endutxent();
return r;
}
static int write_entry_wtmp(const struct utmpx *store) {
assert(store);
/* wtmp is a simple append-only file where each entry is
simply appended to * the end; i.e. basically a log. */
errno = 0;
updwtmpx(_PATH_WTMPX, store);
return -errno;
}
static int write_utmp_wtmp(const struct utmpx *store_utmp, const struct utmpx *store_wtmp) {
int r, s;
r = write_entry_utmp(store_utmp);
s = write_entry_wtmp(store_wtmp);
if (r >= 0)
r = s;
/* If utmp/wtmp have been disabled, that's a good thing, hence
* ignore the errors */
if (r == -ENOENT)
r = 0;
return r;
}
static int write_entry_both(const struct utmpx *store) {
return write_utmp_wtmp(store, store);
}
int utmp_put_shutdown(void) {
struct utmpx store;
init_entry(&store, 0);
store.ut_type = RUN_LVL;
strncpy(store.ut_user, "shutdown", sizeof(store.ut_user));
return write_entry_both(&store);
}
int utmp_put_reboot(usec_t t) {
struct utmpx store;
init_entry(&store, t);
store.ut_type = BOOT_TIME;
strncpy(store.ut_user, "reboot", sizeof(store.ut_user));
return write_entry_both(&store);
}
static const char *sanitize_id(const char *id) {
size_t l;
assert(id);
l = strlen(id);
if (l <= sizeof(((struct utmpx*) NULL)->ut_id))
return id;
return id + l - sizeof(((struct utmpx*) NULL)->ut_id);
}
int utmp_put_init_process(const char *id, pid_t pid, pid_t sid, const char *line) {
struct utmpx store;
assert(id);
init_timestamp(&store, 0);
store.ut_type = INIT_PROCESS;
store.ut_pid = pid;
store.ut_session = sid;
strncpy(store.ut_id, sanitize_id(id), sizeof(store.ut_id));
if (line)
strncpy(store.ut_line, file_name_from_path(line), sizeof(store.ut_line));
return write_entry_both(&store);
}
int utmp_put_dead_process(const char *id, pid_t pid, int code, int status) {
struct utmpx lookup, store, store_wtmp, *found;
assert(id);
setutxent();
zero(lookup);
lookup.ut_type = INIT_PROCESS; /* looks for DEAD_PROCESS, LOGIN_PROCESS, USER_PROCESS, too */
strncpy(lookup.ut_id, sanitize_id(id), sizeof(lookup.ut_id));
if (!(found = getutxid(&lookup)))
return 0;
if (found->ut_pid != pid)
return 0;
memcpy(&store, found, sizeof(store));
store.ut_type = DEAD_PROCESS;
store.ut_exit.e_termination = code;
store.ut_exit.e_exit = status;
zero(store.ut_user);
zero(store.ut_host);
zero(store.ut_tv);
memcpy(&store_wtmp, &store, sizeof(store_wtmp));
/* wtmp wants the current time */
init_timestamp(&store_wtmp, 0);
return write_utmp_wtmp(&store, &store_wtmp);
}
int utmp_put_runlevel(int runlevel, int previous) {
struct utmpx store;
int r;
assert(runlevel > 0);
if (previous <= 0) {
/* Find the old runlevel automatically */
if ((r = utmp_get_runlevel(&previous, NULL)) < 0) {
if (r != -ESRCH)
return r;
previous = 0;
}
}
if (previous == runlevel)
return 0;
init_entry(&store, 0);
store.ut_type = RUN_LVL;
store.ut_pid = (runlevel & 0xFF) | ((previous & 0xFF) << 8);
strncpy(store.ut_user, "runlevel", sizeof(store.ut_user));
return write_entry_both(&store);
}
#define TIMEOUT_MSEC 50
static int write_to_terminal(const char *tty, const char *message) {
int fd, r;
const char *p;
size_t left;
usec_t end;
assert(tty);
assert(message);
if ((fd = open(tty, O_WRONLY|O_NDELAY|O_NOCTTY|O_CLOEXEC)) < 0)
return -errno;
if (!isatty(fd)) {
r = -errno;
goto finish;
}
p = message;
left = strlen(message);
end = now(CLOCK_MONOTONIC) + TIMEOUT_MSEC*USEC_PER_MSEC;
while (left > 0) {
ssize_t n;
struct pollfd pollfd;
usec_t t;
int k;
t = now(CLOCK_MONOTONIC);
if (t >= end) {
r = -ETIME;
goto finish;
}
zero(pollfd);
pollfd.fd = fd;
pollfd.events = POLLOUT;
if ((k = poll(&pollfd, 1, (end - t) / USEC_PER_MSEC)) < 0)
return -errno;
if (k <= 0) {
r = -ETIME;
goto finish;
}
if ((n = write(fd, p, left)) < 0) {
if (errno == EAGAIN)
continue;
r = -errno;
goto finish;
}
assert((size_t) n <= left);
p += n;
left -= n;
}
r = 0;
finish:
close_nointr_nofail(fd);
return r;
}
int utmp_wall(const char *message, bool (*match_tty)(const char *tty)) {
struct utmpx *u;
char date[FORMAT_TIMESTAMP_MAX];
char *text = NULL, *hn = NULL, *un = NULL, *tty = NULL;
int r;
if (!(hn = gethostname_malloc()) ||
!(un = getlogname_malloc())) {
r = -ENOMEM;
goto finish;
}
getttyname_harder(STDIN_FILENO, &tty);
if (asprintf(&text,
"\a\r\n"
"Broadcast message from %s@%s%s%s (%s):\r\n\r\n"
"%s\r\n\r\n",
un, hn,
tty ? " on " : "", strempty(tty),
format_timestamp(date, sizeof(date), now(CLOCK_REALTIME)),
message) < 0) {
r = -ENOMEM;
goto finish;
}
setutxent();
r = 0;
while ((u = getutxent())) {
int q;
const char *path;
char *buf = NULL;
if (u->ut_type != USER_PROCESS || u->ut_user[0] == 0)
continue;
if (path_startswith(u->ut_line, "/dev/"))
path = u->ut_line;
else {
if (asprintf(&buf, "/dev/%s", u->ut_line) < 0) {
r = -ENOMEM;
goto finish;
}
path = buf;
}
if (!match_tty || match_tty(path))
if ((q = write_to_terminal(path, text)) < 0)
r = q;
free(buf);
}
finish:
free(hn);
free(un);
free(tty);
free(text);
return r;
}