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systemd/src/shutdownd.c

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/*-*- 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 General Public License as published by
the Free Software Foundation; either version 2 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <sys/socket.h>
#include <sys/poll.h>
#include <sys/types.h>
#include <sys/timerfd.h>
#include <assert.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include "shutdownd.h"
#include "log.h"
#include "macro.h"
#include "util.h"
#include "sd-daemon.h"
#include "utmp-wtmp.h"
static int read_packet(int fd, struct shutdownd_command *_c) {
struct msghdr msghdr;
struct iovec iovec;
struct ucred *ucred;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
} control;
struct shutdownd_command c;
ssize_t n;
assert(fd >= 0);
assert(_c);
zero(iovec);
iovec.iov_base = &c;
iovec.iov_len = sizeof(c);
zero(control);
zero(msghdr);
msghdr.msg_iov = &iovec;
msghdr.msg_iovlen = 1;
msghdr.msg_control = &control;
msghdr.msg_controllen = sizeof(control);
if ((n = recvmsg(fd, &msghdr, MSG_DONTWAIT)) <= 0) {
if (n >= 0) {
log_error("Short read");
return -EIO;
}
if (errno == EAGAIN || errno == EINTR)
return 0;
log_error("recvmsg(): %m");
return -errno;
}
if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
control.cmsghdr.cmsg_level != SOL_SOCKET ||
control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
log_warning("Received message without credentials. Ignoring.");
return 0;
}
ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
if (ucred->uid != 0) {
log_warning("Got request from unprivileged user. Ignoring.");
return 0;
}
if (n != sizeof(c)) {
log_warning("Message has invalid size. Ignoring");
return 0;
}
char_array_0(c.wall_message);
*_c = c;
return 1;
}
static void warn_wall(usec_t n, struct shutdownd_command *c) {
assert(c);
assert(c->warn_wall);
if (n >= c->elapse)
return;
if (c->wall_message[0])
utmp_wall(c->wall_message);
else {
char date[FORMAT_TIMESTAMP_MAX];
const char* prefix;
char *l = NULL;
if (c->mode == 'H')
prefix = "The system is going down for system halt at ";
else if (c->mode == 'P')
prefix = "The system is going down for power-off at ";
else if (c->mode == 'r')
prefix = "The system is going down for reboot at ";
else
assert_not_reached("Unknown mode!");
if (asprintf(&l, "%s%s!", prefix, format_timestamp(date, sizeof(date), c->elapse)) < 0)
log_error("Failed to allocate wall message");
else {
utmp_wall(l);
free(l);
}
}
}
static usec_t when_wall(usec_t n, usec_t elapse) {
static const struct {
usec_t delay;
usec_t interval;
} table[] = {
{ 10 * USEC_PER_MINUTE, USEC_PER_MINUTE },
{ USEC_PER_HOUR, 15 * USEC_PER_MINUTE },
{ 3 * USEC_PER_HOUR, 30 * USEC_PER_MINUTE }
};
usec_t left, sub;
unsigned i;
/* If the time is already passed, then don't announce */
if (n >= elapse)
return 0;
left = elapse - n;
for (i = 0; i < ELEMENTSOF(table); i++)
if (n + table[i].delay >= elapse) {
sub = ((left / table[i].interval) * table[i].interval);
break;
}
if (i >= ELEMENTSOF(table))
sub = ((left / USEC_PER_HOUR) * USEC_PER_HOUR);
return elapse > sub ? elapse - sub : 1;
}
static usec_t when_nologin(usec_t elapse) {
return elapse > 5*USEC_PER_MINUTE ? elapse - 5*USEC_PER_MINUTE : 1;
}
int main(int argc, char *argv[]) {
enum {
FD_SOCKET,
FD_WALL_TIMER,
FD_NOLOGIN_TIMER,
FD_SHUTDOWN_TIMER,
_FD_MAX
};
int r = EXIT_FAILURE, n_fds;
int one = 1;
struct shutdownd_command c;
struct pollfd pollfd[_FD_MAX];
bool exec_shutdown = false, unlink_nologin = false, failed = false;
unsigned i;
if (getppid() != 1) {
log_error("This program should be invoked by init only.");
return EXIT_FAILURE;
}
if (argc > 1) {
log_error("This program does not take arguments.");
return EXIT_FAILURE;
}
log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
log_parse_environment();
log_open();
if ((n_fds = sd_listen_fds(true)) < 0) {
log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
return EXIT_FAILURE;
}
if (n_fds != 1) {
log_error("Need exactly one file descriptor.");
return EXIT_FAILURE;
}
if (setsockopt(SD_LISTEN_FDS_START, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
log_error("SO_PASSCRED failed: %m");
return EXIT_FAILURE;
}
zero(c);
zero(pollfd);
pollfd[FD_SOCKET].fd = SD_LISTEN_FDS_START;
pollfd[FD_SOCKET].events = POLLIN;
for (i = 0; i < _FD_MAX; i++) {
if (i == FD_SOCKET)
continue;
pollfd[i].events = POLLIN;
if ((pollfd[i].fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC)) < 0) {
log_error("timerfd_create(): %m");
failed = false;
}
}
if (failed)
goto finish;
log_debug("systemd-shutdownd running as pid %lu", (unsigned long) getpid());
sd_notify(false,
"READY=1\n"
"STATUS=Processing requests...");
do {
int k;
usec_t n;
if (poll(pollfd, _FD_MAX, -1) < 0) {
if (errno == EAGAIN || errno == EINTR)
continue;
log_error("poll(): %m");
goto finish;
}
n = now(CLOCK_REALTIME);
if (pollfd[FD_SOCKET].revents) {
if ((k = read_packet(pollfd[FD_SOCKET].fd, &c)) < 0)
goto finish;
else if (k > 0 && c.elapse > 0) {
struct itimerspec its;
char date[FORMAT_TIMESTAMP_MAX];
if (c.warn_wall) {
/* Send wall messages every so often */
zero(its);
timespec_store(&its.it_value, when_wall(n, c.elapse));
if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
log_error("timerfd_settime(): %m");
goto finish;
}
/* Warn immediately if less than 15 minutes are left */
if (n < c.elapse &&
n + 15*USEC_PER_MINUTE >= c.elapse)
warn_wall(n, &c);
}
/* Disallow logins 5 minutes prior to shutdown */
zero(its);
timespec_store(&its.it_value, when_nologin(c.elapse));
if (timerfd_settime(pollfd[FD_NOLOGIN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
log_error("timerfd_settime(): %m");
goto finish;
}
/* Shutdown after the specified time is reached */
zero(its);
timespec_store(&its.it_value, c.elapse);
if (timerfd_settime(pollfd[FD_SHUTDOWN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
log_error("timerfd_settime(): %m");
goto finish;
}
sd_notifyf(false,
"STATUS=Shutting down at %s...",
format_timestamp(date, sizeof(date), c.elapse));
}
}
if (pollfd[FD_WALL_TIMER].revents) {
struct itimerspec its;
warn_wall(n, &c);
flush_fd(pollfd[FD_WALL_TIMER].fd);
/* Restart timer */
zero(its);
timespec_store(&its.it_value, when_wall(n, c.elapse));
if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
log_error("timerfd_settime(): %m");
goto finish;
}
}
if (pollfd[FD_NOLOGIN_TIMER].revents) {
int e;
log_info("Creating /etc/nologin, blocking further logins...");
if ((e = touch("/etc/nologin")) < 0)
log_error("Failed to create /etc/nologin: %s", strerror(-e));
else
unlink_nologin = true;
flush_fd(pollfd[FD_NOLOGIN_TIMER].fd);
}
if (pollfd[FD_SHUTDOWN_TIMER].revents) {
exec_shutdown = true;
goto finish;
}
} while (c.elapse > 0);
r = EXIT_SUCCESS;
log_debug("systemd-shutdownd stopped as pid %lu", (unsigned long) getpid());
finish:
for (i = 0; i < _FD_MAX; i++)
if (pollfd[i].fd >= 0)
close_nointr_nofail(pollfd[i].fd);
if (unlink_nologin)
unlink("/etc/nologin");
if (exec_shutdown) {
char sw[3];
sw[0] = '-';
sw[1] = c.mode;
sw[2] = 0;
execl(SYSTEMCTL_BINARY_PATH,
"shutdown",
sw,
"now",
(c.warn_wall && c.wall_message[0]) ? c.wall_message :
(c.warn_wall ? NULL : "--no-wall"),
NULL);
log_error("Failed to execute /sbin/shutdown: %m");
}
sd_notify(false,
"STATUS=Exiting...");
return r;
}
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